Wärtsilä 50SG Power Plant Product Guide

Issue I: 07.02.2013

DATA AND INFORMATION IN THIS GUIDE IS SUBJECT TO CHANGE WITHOUT NOTICE.

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Wärtsilä 50SG Power Plant Product Guide TABLE OF CONTENTS

TABLE OF CONTENTS
3.5.1 System description .......................................... 40
1. GENERAL ................................................. 5 3.5.2 Lube oil storage tanks ..................................... 41
1.1 Introduction .................................................... 5 3.5.3 Lube oil pump units ......................................... 42
1.2 Applications .................................................... 6 3.6 Compressed air systems .............................. 42
1.3 Plant performance .......................................... 7 3.6.1 System description .......................................... 42
1.3.1 Plant output ...................................................... 7 3.6.2 Starting air unit ................................................ 44
1.3.2 Engine de-rating ............................................... 8 3.6.3 Control and instrument air unit ......................... 45
1.3.3 Start, stop and loading performance ................ 10 3.6.4 Compressed air tanks...................................... 45
1.4 Environmental impacts ................................. 11 3.7 Cooling water system ................................... 45
1.4.1 Exhaust gas emissions.................................... 11 3.7.1 System description .......................................... 45
1.4.2 Noise emissions.............................................. 12 3.7.2 Radiators ........................................................ 48
1.4.3 Water consumption and site effluents .............. 15 3.7.3 Central coolers ................................................ 49
1.4.4 Miscellaneous ................................................. 15 3.7.4 Maintenance water tank................................... 50
1.5 Operation ...................................................... 16 3.8 Intake air system ........................................... 51
1.5.1 Plant operation ............................................... 16 3.8.1 System description .......................................... 51
1.5.2 Output control ................................................. 17 3.8.2 Intake air filters................................................ 53
1.6 Maintenance.................................................. 18 3.9 Exhaust gas system ...................................... 54
1.6.1 Routine maintenance and component life time . 18 3.9.1 System description .......................................... 54
1.6.2 Safety aspects ................................................ 20 3.9.2 Exhaust gas silencers...................................... 55
3.9.3 Rupture disks .................................................. 55
2. ENGINE GENERATOR SET .................... 21 3.10 Emission control systems ............................ 56
3.10.1 General........................................................... 56
2.1 Engine generator set .................................... 21
3.10.2 Oxidation catalyst ............................................ 56
2.1.1 Overview ........................................................ 21
3.10.3 Selective catalytic reduction (SCR) .................. 56
2.1.2 Flexible coupling ............................................. 21
3.10.4 Integration in exhaust gas system .................... 58
2.1.3 Common base frame....................................... 21
3.10.1 Emission testing .............................................. 59
2.1.4 Flexible mounting............................................ 21
2.2 Engine ........................................................... 22
2.2.1 General .......................................................... 22 4. HEAT RECOVERY SYSTEM ................... 60
2.2.2 Main components ........................................... 22 4.1 General .......................................................... 60
2.2.3 Gas injection and ignition ................................ 23 4.2 Heat recovery from exhaust gases ............... 60
2.2.4 Engine mounted equipment............................. 24 4.2.1 System description .......................................... 60
2.2.5 Internal and engine mounted auxiliary systems 24 4.2.2 Heat recovery boiler ........................................ 61
2.2.6 Engine control system ..................................... 26 4.2.3 Arrangements to decrease boiler fouling .......... 61
2.3 Generator ...................................................... 28 4.2.4 Safety valves in the steam / water system ........ 62
2.3.1 General .......................................................... 28 4.3 Heat recovery from cooling water and lube oil
2.3.2 Generator type and size .................................. 28 ....................................................................... 62
2.3.3 Excitation system ............................................ 28 4.3.1 General........................................................... 62
2.3.4 Main terminal box ........................................... 29 4.4 Flexicycle™ power plant ................................ 64
2.3.5 Instrumentation ............................................... 29 4.4.1 System description .......................................... 64
2.3.6 Protection ....................................................... 29 4.4.2 Main equipment .............................................. 64

3. ENGINE AUXILIARY SYSTEMS.............. 30 5. PIPING SYSTEMS ................................... 67

3.1 Overview ....................................................... 30 5.1 Design principles .......................................... 67
3.2 Modularisation .............................................. 31 5.1.1 General principles ........................................... 67
3.3 Standard modules......................................... 31 5.1.2 Pressure and temperature ratings .................... 67
3.3.1 Engine auxiliary module (EAM)........................ 31 5.1.3 Pipe materials ................................................. 67
3.3.2 Exhaust gas module ....................................... 35 5.1.4 Pipe dimensions.............................................. 69
3.4 Fuel gas system ............................................ 36 5.1.5 Flexible pipes and pipe supports ..................... 70
3.4.1 System description.......................................... 36 5.1.6 Trace heating .................................................. 70
3.4.2 Compact Gas Ramp (CGR) ............................. 37 5.1.7 Insulation ........................................................ 71
3.4.3 Main shut-off valve(s) ...................................... 38 5.1.8 Pipe instrumentation........................................ 71
3.4.4 Vent valve ...................................................... 39 5.2 System specific notes ................................... 71
3.4.5 Pressure reduction station............................... 39 5.2.1 Fuel gas pipes................................................. 71
3.4.6 Gas filtration unit ............................................. 39 5.2.2 Lube oil pipes.................................................. 72
3.4.7 Flow metering unit........................................... 40 5.2.3 Compressed air pipes...................................... 72
3.5 Lube oil system............................................. 40 5.2.4 Cooling water pipes ......................................... 73

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Wärtsilä 50SG Power Plant Product Guide TABLE OF CONTENTS

5.2.5 Intake air ducts ............................................... 74 7.2.1 Overview......................................................... 95

5.2.6 Exhaust gas ducts........................................... 74 7.2.2 Generator set PLC .......................................... 96
5.2.7 Miscellaneous ................................................. 75 7.2.3 Manual control unit .......................................... 96
5.2.8 Steam pipes ................................................... 75 7.2.4 Automatic voltage regulator (AVR) ................... 96
5.2.9 Sizing of steam pipes ...................................... 76 7.2.5 Protection relays ............................................. 96
7.3 Common control cabinet.............................. 97
7.3.1 Overview......................................................... 97
6. ELECTRICAL SYSTEM ........................... 77
7.3.2 Common PLC ................................................. 98
6.1 General.......................................................... 77 7.3.3 Synchronization units ...................................... 98
6.1.1 System overview............................................. 77
7.4 Workstations ................................................. 98
6.1.2 Basic system design ....................................... 78
7.4.1 General........................................................... 98
6.1.3 Protection relays ............................................. 78
7.4.2 Operator station WOIS .................................... 98
6.1.4 Protection classes of electrical equipment........ 79
7.4.3 Reporting station WISE ................................. 100
6.1.5 Internal power consumption ............................ 79
7.4.4 Remote monitoring ........................................ 101
6.2 Generator system ......................................... 80 7.4.5 Data sharing with external systems ................ 101
6.2.1 Measurement and protection ........................... 80 7.4.6 Condition based maintenance........................ 101
6.2.2 Neutral grounding ........................................... 80
7.5 Signal and data communication ................. 102
6.3 Medium voltage switchgear .......................... 81 7.5.1 General......................................................... 102
6.3.1 General .......................................................... 81 7.5.2 Signal types .................................................. 102
6.3.2 General design principles ................................ 81 7.5.3 Communication buses ................................... 102
6.3.3 Medium voltage bus bars ................................ 82 7.5.4 Hard-wired signals......................................... 103
6.3.4 Incoming feeder cubicles................................. 82 7.5.5 Control cables ............................................... 103
6.3.5 Main outgoing feeder cubicles ......................... 82
7.6 Functional description ................................ 104
6.3.6 Station transformer feeder cubicles................. 83
7.6.1 Start and stop processes ............................... 104
6.3.7 Bus bar voltage measurement ......................... 83
7.6.2 Output control ............................................... 104
6.4 High voltage substations .............................. 83 7.6.3 Control of auxiliary systems ........................... 106
6.4.1 General .......................................................... 83 7.6.4 Safety functions ............................................ 106
6.4.2 General design requirements .......................... 84
6.5 Transformers ................................................ 85
6.5.1 General .......................................................... 85 8. PLANT LAYOUT.................................... 108
6.5.2 Power (step-up) transformer ............................ 85 8.1 Site layout ................................................... 108
6.5.3 Station transformer ......................................... 85 8.1.1 Site Layout principles .................................... 108
6.6 Low voltage switchgear ................................ 86 8.1.2 Site layout notes............................................ 108
6.6.1 Overview ........................................................ 86 8.1.3 Site layout examples ..................................... 109
6.6.2 Design principles ............................................ 87 8.2 Engine hall layout........................................ 113
6.6.3 Bus bars and conductors................................. 87 8.2.1 Engine generator set distance ....................... 113
6.6.4 Incoming feeders ............................................ 87 8.2.2 Other space requirements ............................. 113
6.6.5 Outgoing feeders ............................................ 87 8.2.3 Layout notes ................................................. 113
6.6.6 Bus bar voltage measurement ......................... 88 8.2.4 Layout example............................................. 114
6.6.7 Emergency generator...................................... 88 8.3 Electrical equipment building ..................... 116
6.6.8 Emergency bus bar ......................................... 88 8.3.1 General......................................................... 116
6.7 DC system ..................................................... 89 8.3.2 Electrical rooms ............................................ 116
6.7.1 DC power consumers...................................... 89 8.4 Tank yard and unloading station ............... 117
6.7.2 DC system design........................................... 89 8.4.1 Tank yard...................................................... 117
6.8 Grounding ..................................................... 90 8.4.2 Pump shelter................................................. 117
6.8.1 General .......................................................... 90 8.5 Pipes and cables ......................................... 117
6.8.2 Grounding grid ................................................ 91 8.5.1 Pipe layout .................................................... 117
6.8.3 Main grounding bar ......................................... 92 8.5.2 Cabling ......................................................... 117
6.8.4 Neutral point grounding ................................... 92 8.6 Hazardous areas ......................................... 118
6.8.5 Lightning protection......................................... 92 8.6.1 General......................................................... 118
6.9 Cabling .......................................................... 92 8.6.2 Classification of hazardous areas.................. 118
6.9.1 General .......................................................... 92 8.6.3 Protection methods in hazardous areas ......... 119
6.9.2 Medium voltage cables.................................... 93
6.9.3 Low voltage cables ......................................... 93
6.9.4 DC cables....................................................... 93 9. SITE, CIVIL WORKS AND STRUCTURES120
6.9.5 Grounding conductors ..................................... 93 9.1 Site considerations ..................................... 120
9.1.1 Site selection criteria ..................................... 120
9.1.2 Geotechnical investigation ............................. 120
7. PLANT CONTROL SYSTEM ................... 94 9.2 Earthworks and site works.......................... 121
7.1 Overview ....................................................... 94 9.2.1 General......................................................... 121
7.2 Generator set control cabinet ....................... 95 9.2.2 Site drainage................................................. 121

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Wärtsilä 50SG Power Plant Product Guide TABLE OF CONTENTS

9.2.3 Underground utilities ..................................... 121 11.2 Engine Technical data................................. 144
9.3 Engine hall foundation................................ 121 11.3 Engine heat balances .................................. 145
9.3.1 General ........................................................ 121 11.4 Generator data (typical) .............................. 146
9.3.2 Engine generator set foundation .................... 122
9.3.3 Material and strength .................................... 124
9.3.4 Floor tolerances ............................................ 124 12. FLUID REQUIREMENTS ....................... 147
9.3.5 Floor drains .................................................. 125 12.1 Fuel gas requirements ................................ 147
9.3.6 Surface treatment ......................................... 125 12.2 Lubricating oils ........................................... 148
9.4 Other foundations ....................................... 125 12.2.1 General requirements.................................... 148
9.4.1 Tank yard and pump station .......................... 125 12.2.2 Additives ....................................................... 148
9.4.2 Stacks, radiators and transformers ................ 125 12.2.3 Approved lubricating oils................................ 148
9.5 Frames, outer walls and roofs .................... 126 12.3 Water quality requirements ......................... 150
9.5.1 General ........................................................ 126
9.5.2 Engine hall ................................................... 126 13. DIMENSIONS AND WEIGHTS............... 151
9.5.3 Auxiliary structures........................................ 127 13.1 Engine generator set ................................... 151
9.6 Interior structures ....................................... 127 13.2 Standard auxiliary equipment ..................... 152
9.6.1 Inner walls, floors, and ceilings ...................... 127 13.2.1 Compact gas ramp ........................................ 152
9.6.2 Lifting and transportation arrangements ......... 127 13.2.1 Engine auxiliary module (EAM) ...................... 153
9.6.3 Stairs, catwalks and landings ........................ 128 13.2.2 Exhaust gas module (EGM) ........................... 153
9.7 Heating, ventilation and air conditioning ... 128 13.2.3 Standard auxiliary units ................................. 154
9.7.1 Process ventilation........................................ 128
9.7.2 Comfort ventilation and air conditioning ........ 129
9.7.3 Air filtering and silencers ............................... 130 APP A. STANDARDS AND CODES ................ 158
9.8 Fire protection............................................. 130
9.8.1 General ........................................................ 130 APP B. UNIT CONVERSIONS ......................... 160
9.8.2 Fire areas ..................................................... 130
9.8.3 Fire alarm system ......................................... 131
9.8.4 Gas detection system.................................... 131
9.8.5 Fire extinguishing systems ............................ 132
9.9 Water supply system .................................. 133
9.9.1 General ........................................................ 133
9.9.2 Water consumption ....................................... 133
9.9.3 Water treatment unit ..................................... 134
9.9.4 Water booster unit......................................... 134
9.9.5 Water storage tanks ...................................... 134
9.10 Waste water systems .................................. 134
9.10.1 Sewage system ............................................ 134
9.10.2 Oily water collection system .......................... 134
9.11 Lighting ....................................................... 135

10. INSTALLATION AND COMMISSIONING137

10.1 Delivery and storage ................................... 137
10.1.1 Engine generator set ..................................... 137
10.1.2 Engine auxiliary equipment and pipes............ 137
10.1.3 Electrical and control system equipment ........ 137
10.2 Installation .................................................. 138
10.2.1 General ........................................................ 138
10.2.2 Installation of engine generator set ................ 138
10.2.3 Installation of auxiliary equipment .................. 139
10.2.4 Installation of piping systems ......................... 139
10.2.5 Installation of electrical and control systems... 140
10.3 Commissioning ........................................... 141
10.3.1 General ........................................................ 141
10.3.2 Pre-commissioning ....................................... 141
10.3.3 Running in and fine tuning............................. 142
10.3.4 Performance tests......................................... 142

11. TECHNICAL DATA ............................... 143

11.1 Engine generator set .................................. 143

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Wärtsilä 50SG Power Plant Product Guide PREFACE

PREFACE

This product guide provides general guidelines and The content of this document is based on the most
technical information for planning land-based power current information available at the time of publica-
plants using the Wärtsilä 18V50SG lean-burn gas en- tion and is subject to change without notice.
gine. The guide is directed to customers and cus-
tomer representatives, designers and sales personnel Data given in this guide – in texts, tables,
with the aim to serve as a plant design overview and graphs, and figures – are to be regarded as typi-
support during the early project phase. cal values or sample values and must not be used
as design data. Actual values may deviate signifi-
This guide does not provide detailed engineering in- cantly from the typical values.
formation.
All power plant design must be in accordance with
locally applicable rules and regulations. Should any
advice, recommendation or requirement given in this
guide differ from the ones given in local, national or
international regulations, the strictest requirements
are valid.
Wärtsilä assumes no responsibility for customer or
contractor designed plants, even in cases where they
are designed in accordance with this guide.

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Wärtsilä 50SG Power Plant Product Guide 1. GENERAL

1. GENERAL

1.1 Introduction

A Wärtsilä 50SG power plant typically comprises one Each engine generator set has its own fuel gas supply,
or several engine generator sets. The main compo- lubrication system, cooling circuits, intake air and
nents of the plant are the gas fired combustion en- exhaust gas systems, and control system. It can there-
gines, the medium voltage generators, the engine aux- fore be started, stopped and operated independently
iliary systems, the electrical system and the control of the other generator sets in the plant. This modular
system. structure is also an advantage at a possible future ex-
tension of the plant.
The engine generator sets are delivered as factory
assembled and tested units. The generators have been Normally, the buildings are newly built and specifi-
sized to match the actual engine power output at site cally designed for power plant operation. In special
conditions. Before delivery, the engines can be opti- cases, existing buildings can be used. A low building
mized for the available fuel gas quality and the emis- height gives the plant the appearance of a light indus-
sion requirements at site. trial facility.
The engine auxiliary systems include fuel gas, lubri- Wärtsilä delivers well over 100 power plants a year, all
cating oil, compressed air, cooling water, intake air, around the world, based on a standard product de-
and exhaust gas systems. Heat recovery and emission sign developed from long experience. If needed, the
control systems can be installed depending on the plants can be adapted to local codes and standards.
project specific requirements. To a large extent, the Also customer-specific requirements can be included.
auxiliary systems are implemented as prefabricated
and tested, skid mounted standard modules and units,
which minimizes the space requirement and simpli-
fies the installation at site.

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Wärtsilä 50SG Power Plant Product Guide 1. GENERAL

Figure 1. Cross section of a typical Wärtsilä 6 x 18V50SG power plant

The Wärtsilä 50SG engine is available in cylinder con-

figuration 18V.

1.2 Applications High efficiency at full and part load, fast start-up time
and quick load response makes the Wärtsilä 50SG
power plants suitable for base load, load following
A Wärtsilä 50SG power plant is suitable for base and reserve capacity applications.
load, intermediate load, and peak-load power genera-
tion. The plant can be used for feeding a large grid In a multi-engine plant the engine generator sets can
(parallel operation) or a limited grid, for instance a be started, stopped and controlled individually, part
manufacturing plant (island operation). It is also pos- of the plant can be running at the required load point,
sible to switch between island and parallel operation. while part of it is kept as reserve capacity.

The plant can be specified for either 50 or 60 Hz. The power generation can be controlled from the
The generator voltage is typically 6 to 15kV (50Hz) or plant’s own control room, and – with proper configu-
4.16 to 13.8kV (60 Hz). Frequency and generator ration – from an external control system, for instance,
voltage can be selected to best suit the project re- a dispatch centre. As options, the control system
quirement. supports power management functions, such as
automatic load sharing, load shedding, automatic start
and stop, and load following.

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Wärtsilä 50SG Power Plant Product Guide 1. GENERAL

Wärtsilä 50SG power plants are also suited for com- Reference conditions
bined heat and power generation (cogeneration).
Heat can be recovered from the exhaust gases, engine Rated power, specific fuel consumption, and emis-
cooling water, and lubricating oil. Heat recovered sions stated in this document are based on the stan-
from the cooling water and lubricating oil is suitable dard reference conditions according to ISO 3046-1;
for hot water distribution systems. Heat from the except for charge air coolant temperature which is 35
exhaust gases – delivered as steam or hot water – can °C (see the table below). For other conditions, reduc-
be used in applications demanding higher tempera- tion of the engine output may be necessary. See sec-
ture heat, such as industrial processes. tion Engine de-rating.
The Wärtsilä 50SG engine performs well at high alti- Condition Value
tudes and in hot ambient conditions. Due to low ex-
Total barometric pressure 100 kPa
haust gas emissions, which can be further reduced
with emission control systems, they can be located in Air temperature 25°C
areas with strict emission limits. Relative humidity 30%
Charge air coolant temperature 35°C
Table 1. Reference conditions including 3 engine
driven pumps, 2 water pumps and 1 lube
1.3 Plant performance oil pump

Generator power
1.3.1 Plant output
The generator power is determined by the generator
efficiency and the power factor according to the for-
General
mula:
The plant output and efficiency depends on the site P×η
conditions, fuel gas quality, generator efficiency, and S=
power factor. It also depends on the plant design and cos φ
the level of the internal power consumption. Maxi-
mum total plant efficiency is obtained in plants utiliz- where:
ing the waste heat from engine exhaust gases and/or
cooling water. S = generator power in kVA (apparent power)
P = engine shaft power in kW
On request, Wärtsilä can provide calculated plant- η = generator efficiency
specific performance data. cosj = cosine j (power factor)

Engine efficiency and optimization Internal power consumption

Although the Wärtsilä 50SG engines have their opti- The plant’s internal power consumption depends on
mal efficiency at full load, they also have a high part- the size and configuration of the plant, the ambient
load efficiency, which can be seen in the engine heat conditions, and the condition of the equipment.
balances found in chapter Technical Data. Typically, the internal power consumption at ISO
conditions for a 10 engine power plant is 1,5% of the
Thanks to the totally electronic engine control- generator power.
system, and that several compression ratios are avail-
able, the engine can be tuned for optimal perform-
ance at different ambient conditions, with different
fuel gas qualities and different emission requirements.

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Wärtsilä 50SG Power Plant Product Guide 1. GENERAL

1.3.2 Engine de-rating

General De-rating factors

De-rating means a temporary or permanent reduction Note! The de-rating diagrams are made for
of maximum power output to protect the engine high methane number optimised engine and
from overloading. De-rating may be necessary due to NOx setting of 500 mg/Nm³ at 5% O2, dry. They
environmental or operational conditions. shall be used guidance purposes only. Project
specific de-rating must be verified by Wärtsilä.
Temperature definitions The graphs below show typical values of the de-rating
The figure explains the temperatures given in the de- factors, value 1 means no de-rating.
rating descriptions below. Engine de-rating is determined by the following de-
rating factors:
KTC
De-rating due to high altitude and/or high suc-
tion air temperature, see Figure 2. This de-rating
factor is a function of suction air temperature (the
temperature at the turbocharger suction flange) and
the maximum achievable pressure ratio of the turbo-
charger compressor. The pressure ratio, in turn, is a
function of the altitude, the NOx setting and the
compression ratio of the engine. Higher suction air
temperature and higher altitude mean increased de-
rating. Low NOx optimized engines (with higher re-
ceiver temperature) require more de-rating, while en-
Table 2. Explanation of temperatures gines with higher compression ratio require less de-
1 = Suction air temperature (temperature rating.
at turbo charger inlet)
2 = Receiver air temperature (tempera- KTC
1.05
ture in charge air receiver) 40 35 25 15 Suction air temperature [°C]
1.00
3 = Charge air cooling water tempera-
0.95
ture
0.90
This is only an example
0.85
The receiver air temperature is defined as the tem- 0.80

perature in the air receiver after the charge air cool- 0.75

ers. The following formulas can be used for estimat- 0.70

ing the receiver air temperature, Treceiver, based on the 0.65

charge air coolant temperature to the engine, TLT: 0.60

0 500 1000 1500 2000 2500 3000 3500 4000 4500
Altitude [m]
Treceiver[°C] ≈ TLT [°C] + 5..+10 °C
Figure 2. De-rating factor KTC. Example with en-
gine speed 500 rpm.

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Wärtsilä 50SG Power Plant Product Guide 1. GENERAL

KGAS KKNOCK
1.05

De-rating due to low fuel gas feed pressure 1.00

and/or low LHV, see Figure 3. Required fuel gas 0.95

flow to the engine depends on the fuel gas feed pres- 0.90

sure before the engine (the pressure at the gas pipe 0.85

0.80
flange on the engine, after the compact gas ramp 45 50 55 Normal charge air reciever temperature [°C]
0.75
(CGR), the lower heating value (LHV) of the fuel gas,
0.70
and the air pressure in the air receiver. The main fuel 0.65
gas valve on the engine is designed to handle a spe- 0.60
cific fuel gas quality. The engine has to be de-rated if 0.55
the fuel gas flow does not correspond to the engine 0.50

demand. Lower LHV or lower fuel gas pressure im- 50 60 70 80 90 100

plies more de-rating. Low NOx optimized engines Methane number [MN]

(with higher receiver pressure) require more de-

rating. Figure 4. De-rating factor KKNOCK

Other factors affecting engine de-rating

Charge air humidity. High humidity requires raised
LT cooling water temperature (and with that raised
receiver air temperature) to avoid condensation in the
charge air cooler. This may lead to de-rating.
Glycol in the cooling water lowers the specific heat
capacity and may lead to derating

Calculating service power

The actual service power can be calculated as:

Figure 3. De-rating factor KGAS. Charge air tem- =Pr ×Kmin

perature 45 °C
where: Px is the brake power under the ambi-
ent conditions at site,
KKNOCK
Pr is rated power
De-rating due to low fuel gas methane number
(MN) and/or high air temperature in the re- Kmin is the lowest de-rating factor:
ceiver, see Figure 4. Knocking (self ignition) in the
cylinder occurs if the fuel-air mixture is exposed to Kmin =MIN(KTC , KGAS ,KKNOCK )
temperatures and pressures that are above its ignition
point. The tendency for knocking is affected by the Other performance corrections
MN value of the fuel gas, the receiver air tempera-
The engine brake efficiency has to be adjusted for
ture, and the compression ratio of the engine. A
ambient air pressure even in cases when the service
lower MN value of the fuel gas or a higher receiver
output is rated output. The rule is that the brake effi-
air temperature implies increased de-rating. Lower
ciency drops 0.5% per 10 kPa lower ambient pres-
compression ratio of the engine, on the other hand,
sure, starting from 85 kPa a (or 0.5% per 1000 m
means less de-rating.
higher altitude starting from 1500 m).
No adjustment of engine efficiency is needed for en-
gine output de-rated for KKNOCK and KGAS.

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Wärtsilä 50SG Power Plant Product Guide 1. GENERAL

1.3.3 Start, stop and loading 1000

W18V50SG engine stop time

performance 900

800 1

The following graphs indicate the start, stop and 700

600
loading performances. The time required for starting

Speed / rpm
2
500
a cold engine depends on the actual cooling water 400
3

temperature, the graphs below are for a preheated 300

engine. The stated time intervals are guidance values 200
1. Stop command, the GRU closes the supply
2. Gas pressure = 0 when rpm = 500
only. 100 3. Gas admission valves deactivated
4. Ignition system disabled
4

The maximum ramp up rate for an engine which has 0 10 20

Time / sec
30 40 50

achieved normal operating conditions is 25 % per

minute. The ramp down rate is 25 % per minute. Figure 7. Engine stop time

W50SG normal start up and loading The following graph shows maximum instant load
1000 20000
increase when running in isolated mode. Furthermore
900 18000

800
4
16000
the stated values are limited to a running engine that
700 14000
has reached nominal operating temperatures, or for
600 12000 an engine which has been operated at above 30%
Power / kWe
Speed / rpm

500 10000 load within the last 30 minutes. Maximum load step is
2
400 3 8000
0 – 28 – 52 – 70 – 84 – 94-100%. To keep the fre-
300
1. Start up preparations, 1 min
6000
quency band ≤1,5%, there must be a 15 seconds de-
200 2. Speed acceleration and synchronisation, 1 min
3. Loading, 10 min
4000
lay between subsequent load steps.
100 4. Total start up and loading time, 12 min 2000
1 Engine conditions: HT-water temperature >60°C
0 0
0 60 120 180 240 300 360 420 480 540 600 660 720 780 Max instant loadstep
Time / sec 30

Figure 5. Engine normal start-up and loading 25

time (preheated engine, HT water temp

20
>60°C
Load step [%]

15

W50SG fast start up and loading 10

1000 20000

900 18000 5 - With engine at normal operating temperature

4 - Max 10% speed drop
800 16000 - Within 1,5% frequency band after 15 seconds
0
700 14000 0 10 20 30 40 50 60 70 80 90 100
Actual load [%]
600 12000
Power / kWe
Speed / rpm

500 10000

400
2
3 8000
Figure 8. Maximum instant load increase at dif-
300 6000
ferent actual loads when running in iso-
200
1. Start up preparations, 1 min
2. Speed acceleration and synchronisation, 1 min 4000
lated mode (island mode
3. Loading, 5 min
100
1 4. Total start up and loading time, 7 min 2000
Engine conditions: HT-water temperature >70°C
0 0
0 60 120 180 240 300 360 420 480
Time / sec

Figure 6. Engine fast start-up and loading time

(preheated engine, HT water temp
>70°C)

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Wärtsilä 50SG Power Plant Product Guide 1. GENERAL

Efficiency Low NOx

optimized optimized
1.4 Environmental impacts engine engine
NOx ppm vol, 90 45
(nitrogen ox- dry, 15% O2
ides)
1.4.1 Exhaust gas emissions Typical set
g/kWh 1.2 0.6
point
General CO ppm vol, 171 249
(carbon dry, 15% O2
Due to the low peak combustion temperature in the monoxide) g/kWh 1.4 2.0
Wärtsilä 50SG engines, the emission of nitrogen ox-
ides (NOx) is relatively low. Running on clean natural CH2O ppm vol, 25.4 34.6
(formalde- dry, 15% O2
gas, the engines have inherently low emissions of par- hyde)
ticulate matter (PM) and sulphur dioxide (SO2).
Typical O2 vol %, dry 11.6 12.0
concentration
Natural gas fired Wärtsilä 50SG engines typically gen-
erate lower carbon dioxide (CO2) emissions com- VOC1 as CH4 ppm vol, 115 140
(volatile or- dry, 15% O2
pared to oil and coal plants due to lower carbon con- ganic com-
tent per fuel energy input and high efficiency of the pounds)
engine. By using co-generation the total efficiency can PM (dry)2 mg/m3, 15 < 10 < 10
be improved and hence relative CO2 emissions per % O2, dry,
produced energy unit further reduced. (0°C & 1
atm)
Wärtsilä 50SG engines can be tuned for reduced NOx Table 3 Emission levels at steady 100% load,
emission levels, which may have a minor impact on constant speed 500RPM or 514RPM, CR
plant efficiency. The plant can also be equipped with = 11
secondary emission control systems.
On project specific basis, the engines can be opti- Notes:
mized to achieve best economical and environmental During start, stop and transient load variations,
performance. the exhaust gas emissions may temporarily devi-
ate from the steady state conditions.
Emission levels
Due to performance and emission optimization
The following table shows typical emission values for the project-specific values might differ from the
the Wärtsilä 50SG engines at stable operating condi- ones given above.
tions at 100% engine load. The table shows the emis-
sions from an efficiency optimized engine and an
engine optimized for low NOx emission.
VOC (Volatile Organic Compounds) is herein de-
fined as total hydrocarbon excluding methane and
ethane. The organic compounds consist of unburned
fuel gas and components generated in the combus-
tion process, such as formaldehyde. The VOC emis- 1 The VOC emissions depend significantly on the compo-
sions depend significantly on the composition of the sition of the fuel gas. An example is calculated for gas con-
fuel gas. taining 97 vol-% methane, 2 vol-% ethane and 1 vol-%
propane. VOC is herein defined as total hydrocarbon ex-
cluding methane and ethane..
2 Measurement method ISO 9096: Determination of par-

ticulate emissions from stationary sources or USA EPA

Method 17: Determination of particulate emissions from
stationary sources.

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Wärtsilä 50SG Power Plant Product Guide 1. GENERAL

Power plant acoustics integrated in the per-

Secondary emission control systems mitting process
The following methods are available for reducing the Power plant noise impact is estimated during the en-
emissions in the exhaust gas system: vironmental impact assessment process. Starting
point is the evaluation of background noise on the
· Catalytic oxidization for reducing CO, CH2O, and area surrounding the power plant. The potential dis-
VOC. turbance to facilities in the plant proximity such as
residences, schools and hospitals can be assessed by
· Selective Catalytic Reduction (SCR) for reducing
environmental noise modelling. The purpose of this
the NOx emission.
acoustical modelling, including structural investiga-
tions, is to optimize the methods used to reduce the
plant noise impact. The modelling process is iterative
1.4.2 Noise emissions by nature:

Suitable solutions for different environments · The estimated plant noise impact is con-
trasted with the ambient or target noise level.
Power plants should be designed to meet set mini-
mum criteria. The requirements set for noise vary · Component selection, process design optimi-
depending on the location of the plant. The noise sation and structural modifications are ap-
limit in or near a residential area, for instance, are plied if needed to reach the set target.
much stricter than in an industrial area.
· The effect of modifications is simulated and
Designing power plants to be located on industrial cross-checked with the ambient or target
areas to the acoustical standards required in residen- noise level until the set target is reached.
tial areas is not feasible. The background noise level is
often relatively high and thus the noise generated by The following aspects are addressed in the acoustical
the plant would not have significant impact on the design of power plant:
ambient noise level. This applies also for plants con-
structed in areas that do not contain sites detrimen- · Optimising the plant layout, selection and lo-
tally affected by noise. cation of noise-critical components.

Varied design criteria · Attenuation of the charge air intake and ex-
haust outlet.
Primary design target is to meet local legislation and
regulations on environmental noise. In absence of · Engine cooling system: type and location of
local norms, international criteria on environmental the radiator or other cooling equipment.
noise such as World Bank Environmental, Health
and Safety (EHS) guidelines can be applied. · Plant ventilation system: ventilation air in-
take, fan-generated noise, outlet noise emis-
The responsibility for environmental noise impact sion.
depends on the scope of the delivery. The noise
emission of a power plant can be specified at a cer- · Power plant building design: optimal wall
tain distance from the site or at specified receptor structures.
positions. Alternatively, the sound power level (noise
It is apparent that the plant noise emission is as much
emission) of plant equipment can be specified.
due to auxiliary components as the actual generating
In a limited equipment delivery project, only the set. One important aspect of power plant acoustics is
noise emission of the delivered equipment can be the design of better and silent auxiliary components.
guaranteed. The emission levels at receptor positions
depend on the auxiliary equipment and plant struc-
tures.

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Wärtsilä 50SG Power Plant Product Guide 1. GENERAL

Engine sound power levels

Engine sound power levels have been measured ac-
cording to ISO9614-2 as applicable. Measurement
uncertainty is ±2dB.

Figure 11. Exhaust gas silencer typical transmis-

sion loss

Charge air sound power levels

Free field sound power spectrum after turbo charger
Figure 9. Engine sound power levels can be seen in Figure 12. Measurement uncertainty is
±3dB.
Exhaust sound power levels
The free field sound power spectrum after turbo
charger can be seen in Figure 10. Measurement in
exhaust duct, actual engine operating conditions.
Measurement uncertainty is ±3dB.

Figure 12. Charge air sound power levels

Typically 35 dB(A) charge air silencers are used in

power plants. Figure 13 shows typical transmission
loss spectrum for a silencer.
Figure 10. Exhaust sound power level

Typically 35 dB(A) exhaust gas silencers are used in

power plants. Figure 11 shows typical transmission
loss spectrum for a silencer.

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Wärtsilä 50SG Power Plant Product Guide 1. GENERAL

Sound power is a measure of acoustical energy radi-

ated by the sound source. Perceived sound pressure
depends on the sound power rating, the distance
from the source, and the environmental conditions.
Figure 14 indicates typical noise levels at different
distances from a plant with six Wärtsilä 18V50SG
engine generator sets and standard attenuation
equipment.
.

Figure 13. Charge air silencer typical transmission

loss

Figure 14. Typical noise levels at different distances from a plant with six W18V50SG and radiators on the roof

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Wärtsilä 50SG Power Plant Product Guide 1. GENERAL

1.4.4 Miscellaneous
1.4.3 Water consumption and At low exhaust gas temperatures, mainly during start-
site effluents up, the exhaust gases may form visible smoke.
With radiator cooling, which is the most common Oil mist emerging with the crankcase ventilation
cooling method, the cooling water is circulated in a gases is reduced with an oil mist separator and is neg-
closed circuit. There are no waste water results from ligible.
the process. Any contaminated water, for instance,
water used for cleaning the equipment, is collected in The flexible mounting of the engine generator sets
a tank. along with elastic material between the floor slabs
dampen the vibrations from the engines so that prac-
The process water consumption when using radiator tically no vibration is transmitted to the environment.
cooling is negligible (less than 4 litres per produced
MWhe). No de-mineralized water is needed. The power generating process produces negligible
amounts of solid waste.
Water consumption for heat recovery systems should
be investigated case-by-case.

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Wärtsilä 50SG Power Plant Product Guide 1. GENERAL

1.5 Operation

Figure 15. Typical control room for a 12 engine power plant

With remote monitoring services, the plant’s person-

1.5.1 Plant operation nel can monitor the plant from a remote location via
a secure internet connection. Provided that the data
General security requirements are fulfilled, remote control can
be implemented.
The operator supervises and controls the plant mainly
from one or more PC workstations, the WOIS work-
Start and stop
stations, in the plant control room. Most actions
needed for normal operation, such as start and stop The operator starts and stops the engines from the
of the engines, synchronization, circuit breaker con- WOIS workstations. The auxiliary units are generally
trol, and change of set points can be done at the kept in an automatic mode, where they are started
workstations. and stopped automatically.
Also manual controls and a mimic diagram are pro- For emergency stop, engine-specific emergency stop
vided. buttons and buttons for stopping the entire plant are
located in the control room. In the engine hall, each
Normally, the plant is operated in automatic mode,
engine has an emergency stop button, and plant
where the control system takes care of the start and
emergency stop buttons can be installed.
stop processes, synchronization and output control.
In manual mode, the operator controls the output
with switches.

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Wärtsilä 50SG Power Plant Product Guide 1. GENERAL

Supervision and control kW control. In this mode the EG set is running at

constant load and its output will not be affected by
Most temperature and pressure measurements can be system changes. This mode is available only for paral-
monitored in the control room. The control system lel operation with the grid.
also records and stores the readings in the WISE
workstation (WISE = Wärtsilä Information System Speed droop control. Droop control is a universal
Environment). load sharing mode and it can be used both for parallel
operation in an island system and for parallel opera-
Abnormal conditions requiring prompt operator ef- tion with the utility.
forts are noted by alarms, which are indicated by
sound and light signals in the control room. Engine Isochronous control. This control mode is intended
alarms may also be indicated by status and alarm an- for island operation only, the system frequency is
nunciator lights in the engine hall. Alarms and events maintained accurately regardless of load variations.
are recorded by the control system. Load sharing between the EG sets is handled by load
sharing lines between the speed controllers.
The operator should also make regular tours around
the plant to check local meters, drain points, vibra- Generator output control
tions, etc.
The following control modes are available:
Personnel requirements
Power factor control. In this mode, which is avail-
When the plant is in operation, personnel should be able only in parallel operation, the control system
present at site, or, if the plant is remotely controlled, strives to keep the power factor (relation between
personnel on duty should be stationed close enough active and reactive power, cosine phi) constant at a
to reach the plant at short notice when needed. set value.
Voltage droop control. Voltage droop is a universal
control mode for sharing reactive load and to control
1.5.2 Output control the voltage. It can be used for parallel operation in
island system and parallel operation with utility.
General
Voltage droop compensation. In this mode, which
When feeding a small isolated grid (island operation), is available only in island operation and requires data
the power generation follows the system load. The communication between parallel units, the reactive
control system controls the frequency (engine speed) load is shared equally between the parallel units and
by regulating the fuel gas supply to the engine and the the voltage is kept at 100%.
voltage by regulating the excitation current of the
generator. When connected to a strong grid (parallel Synchronization
operation), the grid determines the frequency and
voltage. The control system controls the active power Before connecting a generator set to a live bus bar, it
by regulating the fuel supply, and the reactive power must be synchronized. Synchronization is automatic
by regulating the excitation current. with manual backup.

Engine speed and load control Loading and unloading

The following engine control modes are available: In automatic mode, the load is gradually increased
after connecting a generator set to the grid, and
gradually decreased before disconnecting it.

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Wärtsilä 50SG Power Plant Product Guide 1. GENERAL

1.6 Maintenance

All maintenance can be performed without moving

the generating set, while the other units of the plant
1.6.1 Routine maintenance are still running. Proper maintenance ensures high
and component life time reliability and availability of the power plant and
keeps the plant performance on a continuously high
Flexible maintenance of combustion engines level.
The maintenance of combustion engines is easy and Most routine maintenance can be done by the ordi-
requires a minimum of downtime. Keeping strategic nary operating personnel while the engine is in opera-
spare parts for exchange purposes on site, considera- tion. Extended maintenance measures may require
bly reduces the downtime required for maintenance. that the gas is shut-off and the system is vented.

Figure 16. Typical scheduled and unscheduled maintenance impact for 12 independent units

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Wärtsilä 50SG Power Plant Product Guide 1. GENERAL

Maintenance schedule Maintenance

Unit 1
The following schedule gives only an indication of
Unit 2
required routine maintenance and typical time inter-
vals. Unit 3

Unit 4

Interval: Maintenance measure Unit 5

(Operating
hours) Unit x

500 Check function of waste gate valve Running hours

2000 Visual inspection of valve rotators High plant availability due to

maintanance of one unit at a time
Check yoke and valve clearance Hight reliability due to multiple units
4000 Clean and check waste gate valve and Minimum duration of downtime
actuator for sceduled maintenance
Known maintenance schedule
Inspect contact faces of camshaft without correction factor

Check alignment of flexible coupling

Figure 17. Maintenance intervals
6000 Inspect exhaust duct supports and
bellows
Inspect flexible pipe connections Component lifetime and time between over-
8000 Check flexible pipe connections hauls
9000 Clean and check prechamber valve
The following overhaul intervals and lifetimes are for
12000 Inspect / replace turbocharger bearings guidance only. Actual figures may be different de-
18000 Check thrust bearing clearance pending on service conditions. Time between over-
Inspect camshaft driving gear haul intervals and expected lifetimes for the most
Dismantle valve rotators, clean and important components of the W18V50SG engines
inspect are:
Check small end bearing and piston
pin, one/bank Part Time between Expected life
inspection or time (h)
24000 Clean and inspect HT and LT-water overhaul (h)
thermostatic valves
Piston 18000 72000
24000 Clean and inspect oil thermostatic
valve Piston rings 18000 18000
Inspect HT/LT -water pump and driv- Cylinder liner 18000 96000
ing gear Cylinder head 18000 72000
36000 Check bearing clearances in tappets Inlet valve 18000 36000
and rocker arm
Exhaust valve 18000 36000
Inspect one camshaft bearing / bank
Main bearing 18000 36000
Dismantle the damper in crankshaft,
check condition Big end bearing 18000 36000
48000 Inspect turbocharger gas inlet/outlet Main gas admis- 18000 24000
casings sion valve
Table 4. Maintenance schedule (example) Prechamber con- 6000 18000
trol valve
Prechamber 18000 36000
The oil change interval depends on the lube oil qual-
Ignition coil on 2000 18000
ity, operating conditions and engine condition. plug
The need for cooler and filter cleaning is evaluated by Spark plug - 2000
measuring the pressure drop over the devices. Table 5. Time between overhauls and expected
lifetime of components

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Wärtsilä 50SG Power Plant Product Guide 1. GENERAL

Achieved lifetimes are very much depending on the The exhaust gas system should be designed so as to
operating conditions, average loading of the engine, avoid gas pockets, and ventilated after each engine
fuel quality used, fuel handling systems, performance stop. Rupture disks should be installed to minimize
of maintenance etc. the pressure build up in case of a deflagration.
During engine start-up, a number of automatic safety
checks and actions take place. The gas supply is kept
1.6.2 Safety aspects shut off during the first engine revolutions to purge
The safety risks in a Wärtsilä 50SG power plant are any gas in the engine cylinders and exhaust gas pipes.
posed by heavy machines with rotating parts, high
Running time in unloaded condition, where combus-
temperatures and pressures, high voltages, and poten-
tion efficiency is low, is limited.
tially explosive fuel gas mixtures.
In an emergency situation, the gas supply is shut off
A gas explosion may occur if an ignition source arises
and the combustion is disabled immediately.
(spark or hot surface) in a space with a gas - air mix-
ture of an ignitable ratio. In a power plant, the most It is not recommended to stay in the engine room or
serious danger situations are caused by gas leaking in a possible exhaust gas boiler room or silencer
into the engine hall or unburned gas escaping into the room during engine start and no-load operation.
exhaust gas system.
All personnel with access to the plant should be given
In a Wärtsilä 50SG power plant, all reasonable safety safety training.
measures should be employed, for instance:
The plant should be equipped with gas detection and
alarm systems.

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Wärtsilä 50SG Power Plant Product Guide 2. ENGINE GENERATOR SET

2. ENGINE GENERATOR SET

Figure 18. W18V50SG Engine generator set

Since the coupling is flexible, it prevents engine fir-

ing irregularities from being transmitted to the gen-
erator.
2.1 Engine generator set
2.1.3 Common base frame
2.1.1 Overview
The base frame is a welded structural steel assembly
The engine and the generator are factory assembled engineered and reinforced to provide the engine
and aligned, and rigidly fastened to a common base and generator with a stable and torsion resistant
frame of welded steel. At installation, the base platform. A clearance between the generator feet
frame is flexibly mounted to the concrete founda- and the frame resting pads allows for accurate shaft
tion. line alignment by shimming.
The engine crankshaft is connected to the generator Lifting eyes are provided on the frame for lifting the
shaft via a flexible coupling, protected by a flywheel whole generator set. Lateral handling plates allow
cover. for jacking.

2.1.2 Flexible coupling 2.1.4 Flexible mounting

The engine torque is transmitted to the generator To prevent structural born noise and vibration, the
with the flexible coupling located between the en- generator set is mounted on steel springs, which are
gine flywheel and the generator shaft. The coupling normally resting directly on the foundation. The
reduces vibration and provides torque damping steel springs are mounted under the base frame dur-
characteristics. ing installation.
Possible torque due to an inadvertent out-of-phase
coupling or a 3-phase short circuit would deform or
break the elastic elements, which can be easily re-
placed, but the machine structural parts would not
be damaged.

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Wärtsilä 50SG Power Plant Product Guide 2. ENGINE GENERATOR SET

The following picture illustrates the engine termi-

nology.
2.2 Engine

2.2.1 General
The Wärtsilä 18V50SG engine is a four-stroke spark
ignited gas engine, which works according to the
Otto process and the lean burn principle. The en-
gine is turbocharged and intercooled. It is started
with compressed air.

Figure 20. Engine terminology

2.2.2 Main components

Engine block
The engine block is made of nodular cast iron and
cast in one piece. It incorporates the jacket water
manifold, the camshaft bearing housings, and the
Figure 19. Wärtsilä 18V50SG engine charge air receiver. The crankshaft is mounted in
the engine block in an under slung way. The oil
sump, a light welded design, is mounted to the en-
The Wärtsilä 18V50SG engine has the following
gine block from below.
main characteristics:
The engine block has large crankcase doors allowing
Cylinder configuration V-form
easy maintenance.
Number of cylinders 18V
Cylinder bore 500 mm Crankshaft
Stroke 580 mm
The crankshaft is forged in one piece and counter-
Number of valves per cylinder 2 inlet valves
2 exhaust valves balanced by weights on all crank webs.
Rotational direction Clockwise
Main bearings and big end bearings
Rated speed 500/514 rpm
Mean piston speed 9.7/9.9 m/s The main bearings and the big end bearings are of
Mechanical efficiency 0.9 tri-metal design with steel back, lead-bronze lining,
Compression ratio 11:1
and a soft running layer.

Table 6. Engine main characteristics Connecting rods

The connecting rods are of forged alloy steel and
fully machined with a round cross section. The
connecting rod is a three-piece design, which gives a
minimum dismantling height and enables the piston
to be dismounted without opening the big end bear-
ing.

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Wärtsilä 50SG Power Plant Product Guide 2. ENGINE GENERATOR SET

Pistons and piston rings

The pistons are of composite type with nodular cast
iron skirt and steel top. The piston skirt and cylin- 2.2.3 Gas injection and igni-
der liner are lubricated by a unique piston skirt lu-
bricating system equipped with lubricating nozzles tion
in the piston skirt. In a lean burn gas engine, the air-fuel mixture in the
The piston ring set consists of two directional com- cylinders contains more air than necessary for com-
pression rings and one spring-loaded conformable bustion. The ignition is initiated by spark plugs in
oil scraper ring. the pre-chambers, where a richer air-fuel mixture is
used.
Cylinder liners
The cylinder liners are centrifugally cast of a special
alloyed cast iron. The top collar is provided with
bore cooling for efficient control of the liner tem-
perature. The liner is provided with an anti polish-
ing ring.

Cylinder heads
Each cylinder head contains a centrally located pre-
chamber with a fuel gas valve. A multi-duct casting
fitted to the cylinder head contains a charge air inlet
from the air receiver, an exhaust gas outlet, cooling Figure 21. Ignition
water outlet to return pipe, and a gas inlet from gas
manifold. Exhaust gas and inlet valves are equipped
with valve rotators. The gas flame from the pre-chamber ignites the
mixture in the cylinder. The ignition system consists
The cylinder heads are made of vermicular cast iron of two ignition coil drivers, one for each bank, and
(CGI – compacted graphite iron). The valve seat ignition coils located on top of the cylinder head
rings are made of specially alloyed cast iron with covers.
good wear resistance. The inlet valves as well as
exhaust valves have stellite-plated seat faces and
chromium-plated stems.

Camshafts
The camshafts are made up of one-cylinder pieces
with integrated cams. The camshafts are driven by
the crankshaft through a gear train.

Figure 22. Prechamber

Gas is mixed with combustion air only in the intake

channels in the cylinder head, thus ensuring that
only air is present in the intake air manifold.

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Wärtsilä 50SG Power Plant Product Guide 2. ENGINE GENERATOR SET

2.2.4 Engine mounted Turning device

equipment The engine is fitted with an electrically driven turn-
ing device to allow slow turning of the engine. For
Flywheel fine adjustment of the crankshaft position there is a
hand wheel. Engine start-up is prohibited while the
The flywheel is fastened to the crankshaft with fit- turning device is being used.
ted bolts. The generator is connected to the fly-
wheel with a flexible coupling fastened to the fly-
wheel.
2.2.5 Internal and engine
Turbochargers mounted auxiliary sys-
tems
The engine has two turbochargers; one per bank at
the free end of the engine.
Fuel Gas system
The turbochargers utilize the energy of the engine
The fuel gas system consists of a main gas line that
exhaust gases to feed air to the engine, thus, raising
provides gas to the cylinders and a pre-chamber
the efficiency of the combustion. The turbochargers
line. The main gas valves are opened and closed by
are of axial turbine type, each with an exhaust gas
the engine control system. The pre-chamber gas
driven turbine and a centrifugal compressor
injection valves are mechanically operated by the
mounted on the same shaft. The turbochargers are
camshaft.
equipped with in-board plain bearings, and lubri-
cated by the engine lubricating oil system. Input:
Engine control system
- rpm
A water washing device can be used during opera- -kW
-air/fuel
tion. Regular cleaning delays the formation of de- Gas pipe for
main gas valve
-etc

posits.
Camshaft controlled
Exhaust gas waste-gate prechamber valve

The waste-gate valve in the exhaust gas system acts

Main gas
as a regulator that adjusts the charge air pressure at admission valve

high loads. When opened, the valve lets part of the Air
exhaust gases by-pass the turbocharger, thus reduc- Gas pipe for
prechamber gas valve
ing the turbocharger speed and the intake air pres- Prechamber
sure in the receiver. The waste-gate is actuated elec-
tro pneumatically.
Figure 23. Gas admission system
Anti-surge device
An anti-surge device can be installed for applica- Gas is supplied to the engine through the compact
tions where rapid load reductions may occur. The gas ramp with separate outlets for main gas and pre-
function of the anti-surge device is to keep suffi- chamber gas. A gas filter mounted on the engine
cient air flow through the turbochargers at sudden performs a final filtration of the main gas line.
load reductions.
The main gas line on the engine has a vent valve
controlled by the engine control system.

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Wärtsilä 50SG Power Plant Product Guide 2. ENGINE GENERATOR SET

Lubricating oil system Compressed air starting system

The lubricating oil system lubricates bearings and The engine is started by direct injection of com-
cylinder liners in the engine. Besides lubricating the pressed air into the cylinders. Starting air is admitted
engine and the turbo chargers, the lubricating oil to the cylinders through pneumatically controlled
has a cooling function. As a standard the engine is starting air valves in the cylinder heads. Control air
equipped with starting-up/running-in filter(s). An to the starting air valves is fed through a camshaft
engine driven pump located at the free end of the driven distributor. Control air feed is blocked when
engine is available as an option. The suction height the turning gear is engaged, thus preventing start.
must not exceed the capacity of the pump. All the
other equipment belongs to the external lubricating The main starting valve that admits air to the start-
oil system ing system is activated by the engine control system.

Lubricating oil is circulated by an e gear pump. Be- Cooling system

sides the pump, the lube oil system comprises an
automatic oil filter and a centrifugal filter for clean- The main function of the engine cooling water sys-
ing the back-flush oil from the automatic filter, a tem is to remove the heat generated by the engine.
lubricating oil cooler with a thermostatic valve, and The cooling water is cooled in an external cooling
an electrically driven pre-lubricating pump. system.
The cooling water system is divided into a high
Temperature
Automatic filter temperature (HT) circuit and a low temperature
control valve (LT) circuit. The HT circuit comprises the engine
T
block (cylinder jacket and cylinder heads) and the
first stage charge air cooler. The LT circuit com-
Filter for back-
flushing oil prises the second stage charge air cooler.
Two engine driven centrifugal pumps circulate the
Oil cooler cooling water through the engine and the external
Circulation pump cooling system. The water temperatures in the two
circuits are controlled by two temperature control
valves.
Prelubricating pump
Intake air system
Figure 24. Internal and built on lube oil system
The intake air system comprises the compressor on
Lube oil is also conducted to other lubricating the turbocharger and a two-stage intake air cooler
points, like camshaft bearings, rocker arm bearings, of tube type located after the turbocharger. When
valve mechanism gear wheel bearings, and the tur- compressed in the turbocharger, the air is heated. In
bocharger. the charge air cooler, it is cooled with cooling water
to optimal level before entering the charge air re-
The electrically driven pre-lubricating pump is used ceiver in the engine block.
for filling the engine lube oil system before start,
and for continuous lubrication of engines in stand- Exhaust gas system
by.
The engine is equipped with a Monospex (single
The engine is equipped with a wet oil sump. The pipe exhaust) turbo charging system, which com-
sump is equipped with high and low level switches, bines the advantages of both pulse and constant
an oil dipstick indicating maximum and minimum pressure charging. The interface between the engine
oil levels and remote level indication. and the turbocharger is streamlined with a mini-
mum of flow resistance on both exhaust and air
side.

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Wärtsilä 50SG Power Plant Product Guide 2. ENGINE GENERATOR SET

The exhaust pipes have separate sections for each

cylinder. Metal bellows of multiple type absorb the
heat expansion. The complete exhaust system is
enclosed by an insulation box of steel sheets.
Exhaust gas temperature sensors are mounted after
each exhaust valve, and before and after the turbo-
chargers.

Figure 25. UNIC main system components

2.2.6 Engine control system
General The system is specifically designed for the demand-
ing environment on engines. Special attention has
Monitoring and control of the engine is handled by been paid to temperature and vibration endurance.
the engine mounted engine control system, UNIC The rugged design allows the system to be directly
(UNIfied Controls). The main functions of the sys- mounted on the engine, and the engine can be fully
tem are: tested at the factory before delivery.

· Start and stop management UNIC collects signals from the engine sensors,
processes them and compares them with given con-
· Engine speed and load control trol parameters. All data collected by UNIC can be
transferred to the plant control system.
· Speed measuring and over-speed protection
The local control panel on the engine mounted con-
· Gas pressure control and air-fuel ratio control trol cabinet contains two graphical displays, one
· Cylinder control: gas injection, ignition and static display showing the most important engine
knock control parameters, and one interactive, menu based display
where all engine data as well as the control system
· Safety functions: start blocking, alarm activation, status can be viewed.
load reduction, and shutdown.
The Wärtsilä UNIC control system is a distributed
and redundant control system composed of several
hardware modules which communicate through two
redundant communication buses using the CAN
protocol. The main modules are mounted in the
control cabinet at the driving end of the engine. The
I/O modules and the cylinder control modules are
mounted along the engine side close to the sensors
and actuators they are monitoring and controlling.
The main control module is responsible for all con-
trol functions. It communicates with the plant con-
trol system through the plant network.

Figure 26. Engine mounted control cabinet

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Wärtsilä 50SG Power Plant Product Guide 2. ENGINE GENERATOR SET

Engine speed and load control Cylinder control

The engine control system has two engine control Each engine has several cylinder control modules
modes: speed control and load control. The active which control the gas injection and timing of the
mode is selected with the plant control system. main gas valve, peak cylinder pressure, and the igni-
tion timing. They also monitor the exhaust gas tem-
A PID type controller controls the fuel injection perature, cylinder knocking, cylinder liner and main
based on the difference between measured speed or bearing temperatures.
load, depending on the active control mode, and the
respective set point. In speed control mode, a fixed UNIC controls the duration and timing of the gas
speed based on the engine rated speed is used as set injection to each cylinder main combustion cham-
point. The internal engine speed reference is de- ber and the timing of the spark. The timing can be
creased linearly at increased load (speed droop). In set individually for each cylinder.
load control mode, the load reference is set by the
plant control system. Knocking is due to the auto-ignition of gas before
or after the spark ignition. This is harmful to the
Engine speed measuring and over-speed engine. Knock sensors are mounted on each cylin-
der head, and if knocking is detected, UNIC takes
protection
appropriate actions – adjustments, load reduction or
The engine speed and phase are measured with two shutdown – depending on the knock intensity.
speed and phase sensors located on the flywheel.
During operation, the system monitors the exhaust
The speed and phase signals are used to determine
gas temperature of each cylinder and the average
the timing and duration of the gas injection and
temperature. Deviations may lead to load reduction
ignition. Using the speed signals, UNIC calculates
or shutdown.
measured engine speed, which is used as feedback
for the internal speed controller and for over-speed
protection. UNIC calculates the speed in several Safety functions
different units, and the results are cross-checked. The safety functions include start blocking, alarm
In case of an engine over-speed, UNIC initiates an activation, load reduction, shut-down and emer-
instant emergency stop. A safety module in UNIC gency stop.
provides an independent second over-speed protec- Before the plant control system activates a start re-
tion based on two back-up speed sensors. quest, it checks with UNIC that the engine is ready
for start. UNIC will not allow start if, for instance,
Gas pressure and fuel-air ratio control the lubricating oil pressure is too low, the HT cool-
ing water temperature is too low, the exhaust gas
Gas pressure is monitored and controlled to ensure
ventilation has not been performed, or the engine
proper gas supply and air-fuel ratio. Taking into
turning device is engaged.
account the engine load and the air receiver pres-
sure, UNIC calculates and sends a pressure refer- UNIC generates a number of alarms, all of which
ence signal to the compact gas ramp. are transmitted to the plant control system, for in-
stance:
The actual gas pressure is measured on the engine
and compared to the reference pressure. If the gas
· Sensor failure or wire break
pressure is too low or high related to the charge air
pressure, the engine is shut down. If the pressure is · Gas pressure deviation
too high, the control system will open safety valves
on the engine and the compact gas ramp to evacu- · High exhaust gas temperature after a cylinder
ate excess gas pressure.
· Failed start attempt
The air pressure in the air receiver is controlled with
· High charge air temperature
the waste-gate valve.

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Wärtsilä 50SG Power Plant Product Guide 2. ENGINE GENERATOR SET

· De-rating caused by knocking Frequency 50 Hz 60 Hz

· Engine overload. Engine speed, rpm 500 rpm 514 rpm

Number of poles 12 (6 pairs) 14 (7 pairs)
Some alarms, for instance, heavy knocking, gas
Table 7. Number of poles in 50 Hz and 60 Hz
pressure deviation, and high exhaust gas tempera- applications
ture will initiate a load reduction. More serious inci-
dents, like CAN bus failure, high crankcase pres-
sure, high exhaust gas temperature after cylinder, The rotor construction is salient pole. A fully inter-
high cylinder liner temperature, and high main bear- connected damper winding stabilizes the rotor dur-
ing temperature will activate an immediate engine ing load changes. This makes the generator suitable
shut-down. for operation in parallel with other generating sets.

At an emergency stop, the engine will be shut down The generator is sized for the engine power at the
immediately. An automatic emergency stop will be site where the engine generator set will be installed.
executed, for instance, at engine overload, engine
over-speed, or if both speed sensors have failed.
2.3.3 Excitation system
While the active power output from the generator
depends on the engine power and the generator
2.3 Generator efficiency, the voltage and reactive power is regu-
lated by the excitation system.

2.3.1 General The brushless excitation and voltage regulation sys-

tem consists of an automatic voltage regulator
The generator converts the mechanical power of (AVR), an exciter and a rotating diode bridge. Exci-
the engine into electrical power. tation power is taken from voltage transformers or
auxiliary windings mounted on the generator. Due
The standard generators used with Wärtsilä 50SG to a permanent magnet pole in the exciter, no ex-
engines are medium voltage synchronous AC gen- ternal power source is required for the initial excita-
erators with a brushless excitation system, horizon- tion at start-up.
tally mounted, and provided with two sleeve bear-
ings. The generators are connected to the engine
flywheels by means of flexible couplings. The stator
frames rest on machined feet.
The generators are air-cooled with a shaft-mounted
fan which takes cooling air from the engine hall. An
electrical anti-condensation heater prevents water
condensation in a stand-by generator. Figure 27. Principle scheme of the excitation sys-
tem
The generators follow the design criteria described
by IEC (International Electrical Commission).
At full load, the power plant has an operating range
from a power factor of 0.95 leading (under-excited)
to a power factor of 0.8 lagging (over-excited).
2.3.2 Generator type and
size The automatic voltage regulator is contained in the
generator set control cabinet.
Generators are typically operated at nominal speed.
The output frequency is determined by the number
of pole pairs and the engine speed.

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Wärtsilä 50SG Power Plant Product Guide 2. ENGINE GENERATOR SET

2.3.4 Main terminal box 2.3.6 Protection

All stator winding ends and the neutral point cable The generator is protected by the protection relays
are brought into the main terminal box, which is in the generator set control cabinet.
mounted on the generator side or on top of the
generator. If the generator circuit breaker in the MV switch-
gear is of vacuum breaker type, the generator must
be equipped with surge protection (surge arresters
and surge capacitors).
2.3.5 Instrumentation
The generator has current and voltage measurement
transformers which provide measured data for con-
trol and protection functions. In addition, the stator
windings and the bearings are equipped with tem-
perature sensors. All signals from the sensors are
connected to a connection box on the generator.

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Wärtsilä 50SG Power Plant Product Guide 3. ENGINE AUXILIARY SYSTEMS

3. ENGINE AUXILIARY SYSTEMS

3.1 Overview

The auxiliary systems provide functions for fluid

handling and control. They facilitate storage, trans-
fer and conditioning of the operation media at the
correct process parameters. Some functions are
common for several engines, for example, com-
pressed air units and maintenance water tank(s),
while other units, such as the engine auxiliary unit,
compact gas ramp and exhaust gas module are en-
gine specific.

Figure 28. Overview of W50SG engine auxiliary system equipment

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Wärtsilä 50SG Power Plant Product Guide 3. ENGINE AUXILIARY SYSTEMS

A Pipe rack is connecting an EAM to the next one,

and it is designed for connecting max 6 engines to-
3.2 Modularisation gether. In some cases more engines can be con-
nected, but this will require special arrangements.
A module is a part of a system, where several com- The following components are included:
ponents have been built together onto a common
frame to perform one or more functions. Some · pipes
modules combine functions of several systems. Mod-
ules have standardised interfaces, enabling inter- · valves
change ability and offering more alternatives in sys-
· pumps
tem design.
· heaters
Some of the benefits of modularisation are:
· instrumentation and control devices.
· pre-designed solution
The module also includes the trunk route pipes for
· fast and easy installation on site supply of fluids from common storage/transfer sys-
tems to engine-specific circuits. These functions in-
· proven design
clude:
· quality control
· filling of new lubricating oil
· optimised piping
· drainage of used lubricating oil
· compact assembly
· filling of fresh water to the cooling circuit
· standardised connection interfaces
· drainage of cooling circuit to maintenance tank
· Optimised transport dimensions.
· supply of media to the oil-wetted charge air filters,
if such are used
· supply of compressed air for starting the engine
3.3 Standard modules and supplying air operated devices.
The EAM also performs the following functions at
engine start/standby:
3.3.1 Engine auxiliary module
(EAM) · pre-heating of cooling water to 70 C

General · pre-lubricating.
The EAM is a module facilitating the external sys-
tems for conditioning of the fluids, including cooling
and temperature regulation of cooling water and lu-
bricating oil for an individual engine.

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Wärtsilä 50SG Power Plant Product Guide 3. ENGINE AUXILIARY SYSTEMS

Figure 29. 1-C EAM EL with pipe rack and Compact Gas Ramp.

Lube oil system equipment Compressed air system equipment

For lube oil flow control the EAM module comprises Starting air pipes within the EAM convey starting air
a temperature control valve, pipes for transporting to the engine, and control air pipes convey control air
lube oil to the engine, and connections for pumping (instrument air) to the consumers. Control air is dis-
lube oil from the engine. The EAM with pipe rack is tributed through one or more pressure reduction
also including the lube oil treatment system consist- units, containing an air pressure regulating valve, a
ing of: filter and a water separator. The EAM module is also
equipped with a service air outlet.
· Duplex safety/by-pass filter (EAM)
· Lube oil automatic filter (pipe rack) To protect the most sensitive engine components at a
· Back flushing filter (pipe rack) malfunction of a compressor filter or drier, there is a
safety filter (micro filter) in the EAM module close to
· Oil mist separator (pipe rack)
the engine
The treatment system is flexible and ensures that the
engine can be operated during for instance automatic Cooling water system equipment
filter maintenance.
The EAM module contains a HT pre-heating unit
for heating the high temperature (HT) cooling water
before engine start-up. Jacket water is the most criti-
cal part of the engine that must be preheated. The
preheating unit consists of a centrifugal pump and an
electrical heat exchanger designed to heat the cooling
water to about 70°C and to keep it at this tempera-
ture when the engine is stopped.

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Wärtsilä 50SG Power Plant Product Guide 3. ENGINE AUXILIARY SYSTEMS

For cold climates (cold suction air), the 1-Circuit The sensors, switches and actuating devices in the
module may also contain a similar LT pre-heating EAM module are all connected to the remote I/O. In
unit for pre-heating the low temperature (LT) water addition, the sensors and actuators in the exhaust gas
and by that having warm water in the charge air cool- module (see below) and the intake air filter are con-
ers. The warm charge air coolers then heats up the nected to the remote I/O.
cold suction air so that receiver air is warm enough
for a stable combustion. In automatic mode, the pumps and heaters in the
module are started and stopped automatically based
For the 2-circuit module, the HT charge air cooler is on the engine running signal, level switches or ther-
part of the HT water circuit and therefore the LT mostats.
pre-heater is not needed.
Variety and selection criteria
The module contains two cooling water temperature
control valves, one for the LT and one for the HT The optimal configuration of the plant will vary de-
circuit. pending on the application and environmental condi-
tions. To satisfy this need, the EAM comes in two
An expansion water pressure increasing pump can be basic configurations, 1-circuit or 2-circuit, which can
added in cases where the open type HT expansion then be combined with different cooling connections.
vessel (in two-circuit systems) cannot be placed high Both types are available with an optional heat recov-
enough. It should be placed at least 7 meters above ery connection.
the engine HT cooling water pump.
The standard applications for the cooling water sys-
Instrumentation and control tem are shown in Table 8.
The control cabinet of the EAM module contains
pump motor starters, relays, switches, timers and
logical circuits. It also contains a remote I/O which
communicates with the generator set PLC in the con-
trol room.

Cooling wa- Ambient temp

Model Preheater Application
ter system (typical)
W50SG EAM 1-C EL 1-Circuit Jacket Optional LT Mixed cooling. Optional heat recov- -38°C to +50°C
W50SG EAM 1-C STEAM ery connection can be used when a
limited amount of jacket water is
needed for heat recovery
W50SG EAM 2-C EL 2-Circuit Jacket + Optional LT Heat recovery from HT side with an -8°C to +48°C
W50SG EAM 2-C STEAM additional 3-way HT valve and an
external heat exchanger
Heat recovery with dump cooler. -38°C to +48°C
An additional 3-way HT valve and a
HT dump cooler for cooling HT
water with the LT circuit
Separate HT and LT circuits -8°C to +48°C
Table 8. Engine auxiliary modules and applications

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Wärtsilä 50SG Power Plant Product Guide 3. ENGINE AUXILIARY SYSTEMS

1-circuit engine auxiliary modules This is in most cases the preferred solution due to
better temperature gradient and possibility to have
In a 1-circuit cooling system, both stages of charge air lower receiver air temperatures. LT preheating is
cooling (high and low temperature) are connected in needed when ambient the temp is below +5°C
series in the same circuit. The water flows through
the second (low temperature) stage of the charge air The 1-circuit solution can provide a forward tempera-
cooler (LT CAC), the lube oil cooler (LOC) and then ture of maximum 91°C jacket water for optional heat
through the first stage (high temperature) of the recovery. A typical application for this solution is
charge air cooler (HT CAC). condensate heating in combined cycle power plants.

Figure 30. 1-circuit cooling water system EAM with mixed cooling, HR connection and radiator cooling.

2-circuit engine auxiliary modules This solution can provide a forward temperature of
maximum 96°C, and is therefore typically used when
In a 2-circuit cooling system, the low temperature high temperature heat recovery is needed from the
(LT) circuit cools the second stage charge air cooler engine cooling water. The heat recovery equipment is
(LT CAC) and the lubricating oil cooler (LOC). The located outside the EAM.
high temperature (HT) circuit cools the cylinder jack-
ets and the first stage charge air cooler (HT CAC).

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Wärtsilä 50SG Power Plant Product Guide 3. ENGINE AUXILIARY SYSTEMS

Engine EAM
HR Connection

1st HT TCV 2nd HT TCV

CHARGE
AIR

HT CAC

LOC

LO PUMP

Radiator /
LO TCV (Central cooler)
(Cooling tower)

LT CAC

LT TCV

Figure 31. 2-circuit cooling water system EAM with heat recovery from HT water and radiator cooling.

Separate HT and LT circuits Intake air silencers

The 2-circuit system can also be used without an
“application”, but this is a rarely used solution. In this The charge air silencers are of absorption type, and
case the external cooling system (2-circuit radiators) is designed to give about 45 dB(A) attenuation in the
connected directly to the inlet/outlet connections of high frequency band.
the EAM, separately for HT and LT circuits.

3.3.2 Exhaust gas module

General
The exhaust gas module contains an optimized ex-
haust gas branch pipe, intake air silencers, one or two
expansion vessel(s), an exhaust gas ventilation fan,
and an oil mist separator unit. In plants with an SCR
type emission control system, the module may in-
clude a platform for the reagent dosing unit.

Figure 32. W18V50SG Exhaust gas module

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Wärtsilä 50SG Power Plant Product Guide 3. ENGINE AUXILIARY SYSTEMS

Cooling water expansion vessel(s) Fuel gas is supplied to the engine from the gas distri-
bution system through an engine-specific compact
The expansion vessel(s) compensate for volume gas ramp (CGR), which includes a particle filter, pres-
changes in the cooling water system due to tempera- sure control valves, safety shut-off valves and vent
ture changes. They also provide continuous air vent- valves. The CGR is always supplied by Wärtsilä along
ing of the engine cooling water circuit(s) and static with the engine.
pressure at the inlet of the engine mounted cooling
water pumps. Gas is supplied to the power plant through a com-
mon gas pipe which splits into engine-specific gas
In two-circuit installations and one-circuit installa- pipes in a header pipe. To enable gas shut off, there
tions with separate jacket cooler, there are two vessels must be two main shut off valves, one manual and
of 600 litres each, one for HT water and one for LT one automatic type outside the engine hall. Generally,
water. In one circuit installations with mixed HT and the valves are located in the common gas pipe. Alter-
LT water, there is one expansion vessel of 1200 litres. natively, there may be main shut-off valves in each of
The expansion vessels are equipped with low level the engine-specific gas pipes.
switches for activating low level alarm, and local level
indicators. See layout notes on page 113. A gas flow metering device can be installed in the
common gas pipe for measuring the gas consumption
Exhaust gas vent fan of the plant. Engine-specific flow meters may also be
included in the compact gas ramp.
The exhaust gas vent fan purges the exhaust gas pipe
from any accumulated unburned gas. The fan is of The common fuel gas system can also include the
radial type and is driven by an electrical motor. It is following equipment:
started automatically by the plant control system after
every engine stop. A flow switch ensures that the fan · A pressure reduction station if the pressure
is running. supplied by the gas company is higher than maxi-
mum allowed pressure to the CGR
· A gas compressor if the fuel gas pressure sup-
plied by the gas company is too low
3.4 Fuel gas system · A filtration unit if the gas may contain impurities,
oil, water or condensed hydrocarbons
3.4.1 System description · A heating unit if the gas temperature may drop
below the dew point
System overview
· A venting valve to depressurize the fuel gas pipes
The purpose of the fuel gas system is to supply the inside the engine hall
engine with a constant gas feed of suitable pressure,
temperature and cleanness. It should also shut off the The filtration and heating units may be included in
gas supply if any problem arises, and provide ventila- the pressure reduction station as shown in Figure 33.
tion of trapped gas.

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Wärtsilä 50SG Power Plant Product Guide 3. ENGINE AUXILIARY SYSTEMS

Figure 33. Diagram of a fuel gas system with common gas shut off and flow metering, and a pressure reduction
station with filtration and heating

Fuel gas pressure requirements Gas filtration

The required fuel gas pressure to the engine depends The mechanical components in the engine fuel gas
on the engine configuration and the heating value of system are sensitive to particles. Particles must there-
the gas. The exact minimum pressure must therefore fore be removed before the engine. The maximum
be determined case by case. allowed particle size is 5 µm at plant inlet at an
amount of 50 mg/m3 at 0ºC and 101,325 kPa. No
Normally, the inlet pressure to the CGR is 5-8 bar(g),
water and liquid hydrocarbon condensate is allowed.
and the typical pressure drop over the CGR is 50
kPa.
The required fuel gas pressure to the plant is the 3.4.2 Compact Gas Ramp
minimum CGR pressure, plus the pressure drop over (CGR)
the upstream units, plus a safety margin.
General
Temperatures
The Wärtsilä designed compact gas ramp is the rec-
The fuel gas temperature before the engine must be ommended type of gas regulating unit. The compact
high enough to avoid condensation and icing. The gas ramp controls the gas feed pressure according to
recommended minimum temperature is +5oC, or the engine load and performs a leakage test of the
minimum of +15oC over the hydrocarbon and water main shut-off valve after every engine stop.
dew points. Whichever highest.

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Wärtsilä 50SG Power Plant Product Guide 3. ENGINE AUXILIARY SYSTEMS

Control valves
The pneumatic gas regulating valve regulates the out-
let pressure of the fuel gas. The gas pressure is con-
trolled by the engine control system based on the
charge air pressure, through a position reference to
the control valve
The correct size of the valve is selected based on the
project specific pressure, temperature and flow to get
an optimum control of the pressure.

Vent valves
The automatic venting valves are pneumatically oper-
Figure 34. Compact gas ramp ated. The venting valve between the shut-off valves is
always open when the engine is stopped. The shut-off
valves are closed pneumatically and opened by a
The main components of the CGR are: spring.
· Gas inlet valve
· Gas filter 3.4.3 Main shut-off valve(s)
· Automatic shut-off valve To enable fuel gas shut off, there must be one or
more main shut off valves outside the engine hall. In
· Gas regulating valve the event of a gas leak, fire or gas explosion inside the
· Insert gas connection building, the gas flow must be shut off automatically.
It must also be possible to shut off the gas flow
· Venting line manually outside the building. It is therefore recom-
mended to have two valves in series, one manually
Junction box and one automatically operated. The automatic valve
must be of fail-safe type with a limit switch for re-
The box is designed for installation in an Ex area. mote indication.

Gas filter Minimum performance requirements for large valves

>DN200:
The fuel gas is cleaned in a cartridge filter. The filter
is equipped with a differential pressure indicator to Shut off: < 4 seconds
monitor the condition of the filter. Open: ~30 seconds
For smaller valves, shorter closing time is recom-
Automatic shut off valves mended.
The automatic shut-off valves and venting valves are
The design of the valves shall be fire safe.
operated during the start and stop sequences, and
they are controlled by the engine-specific PLC. Generally, the main shut off valves are located in the
common gas pipe before the header pipe. Alterna-
The shut-off valves are opened pneumatically and
tively, there may be main shut-off valves in each of
closed by a spring. The valves are ball type valves and
the engine-specific gas pipes. The latter design may
fulfil EN161 (A) standard for automatic shut off
be preferable in cold climates as it allows engine ven-
valves. Together with the first automatic venting
tilation to be shut off during standby.
valve the shut off valves form a double block and
bleed connection

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Wärtsilä 50SG Power Plant Product Guide 3. ENGINE AUXILIARY SYSTEMS

In plants with a common main shut-off valve, the Safety devices

automatic valve is closed by the control system at a
plant emergency stop. In plants with engine specific Depending on the inlet and outlet pressures, one or
valves, the valve is closed at stop, shut-down, or more safety devices are required. The recommended
emergency stop of the respective engine. All valves installation is two safety shut off valves. When acti-
are closed in case of a plant emergency stop. vated (closed), the safety shut-off valve must remain
closed until it is opened manually.

3.4.4 Vent valve

3.4.6 Gas filtration unit
A vent valve is installed outside the engine hall be-
tween the main shut-off valve and the wall. The valve General
is opened in case of a plant emergency shutdown to
let pressurized fuel gas out of the fuel gas pipes. The A gas filtration unit is needed if the gas contains or
valve should be of fail-safe type and opened by a may contain high concentrations of impurities in the
spring in loss of power or control air. To safeguard form of particles – rust, debris, sand, etc. – oil, or
the operation of the shut off and vent valve the moisture and hydrocarbon condensate. If there is a
valves needs to be interlocked and have position gas compressor, it may leave traces of lubrication oil
feedback. in the gas stream. Liquid removal and also gas heating
may be required depending on the inlet temperature
and pressure, and the hydrocarbon and water dew
3.4.5 Pressure reduction sta- points of the gas. The filter type may be, for instance,
a particle, coalescing, vane, or demister filters. All
tion electrical devices must be EX-classified.
General Liquid separation
The design of a pressure reduction station can vary. Natural gas containing traces of C4 - C7 hydrocar-
In addition to the pressure regulator, the station may bons and a slight amount of water vapour normally
include a filter, a gas flow meter, a heater, and a gas needs no liquid separation. However, if the gas con-
chromatograph for measuring the gas quality. tains higher hydrocarbons, C12 or higher, liquid sepa-
ration will be necessary as these compounds may
Pressure regulating valves cause condensation problems even in small concen-
To secure the availability, the unit shall be designed trations (e.g. 0.5 ppm).
with two parallel lines. Both lines are designed for Liquids can be separated, for instance, with gravity
100 % capacity and equipped with safety shut-off separators, centrifugal separators, vane separators,
valves. An automatic duty/slave control switches to mist eliminator pads and coalescing filters. Generally,
the slave line if the duty line fails. The set points are the liquid present in the gas stream is a very fine fume
adjusted so that if one regulator fails, the other one with a droplet diameter < 1 mm. For removing such
takes over. small droplets, a coalescing filter is normally required.
Heating
When the pressure is reduced, the fuel gas tempera-
ture will drop. The size of the drop depends on the
gas composition. A rule of thumb is 0.5 oC/bar. The
temperature drop may cause condensation, icing and
hydrate formation. If a risk for malfunction arises,
heating is required. The components must be EX-
classified.

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Design principles 3.5 Lube oil system

The filtration unit should have full stand-by capacity
and be designed for maximum flow (the flow at the
minimum operating pressure and maximum tempera- 3.5.1 System description
ture). The filter must be equipped with differential
pressure measurement and filter switch over. There The lubrication oil system includes tanks for storing
should also be manual venting and isolation valves or new and used lube oil, pumps for emptying and fill-
three way valves. If liquid is removed, a manual or ing lube oil, and loading/unloading pump units in the
automatic drain and possibly a collector will be tank yard. The pump for filling lube oil can be com-
needed. If the filter is installed indoors, normal car- mon for the entire plant. A common mobile pump
bon steel can be used. can be used for emptying the system.

3.4.7 Flow metering unit

General
The gas flow is metered for determining the fuel con-
sumption. The gas flow meter can be an industrial
meter or a custody transfer meter approved for bill-
ing purposes. The flow meter must be equipped with
a flow corrector or a computer to change the actual
flow to standard conditions. For more exact flow
determination, the compressibility of the gas should
be taken into account.

Design
The plant specific flow meter includes:

· A flow meter, normally a turbine meter, with a

flow corrector or computer
· High accuracy pressure and temperature sensors
· A particulate filter Figure 35. A typical lube oil system

· A by-pass line, a vent connection, isolation valves,

The new lube oil tank stores fresh lubricating oil for
and straight pipe sections before and after the me-
oil changes and for compensating oil consumption
ter
(topping up). The used lube oil tank contains used
The meter shall be the same size as the gas pipe. Re- lube oil stored for disposal. There may also be a ser-
stricting or enlarging cones are not recommended. vice tank for storing lube oil temporarily for reuse.
The valves must be designed for gas applications.
The required size for the fresh lube oil tank depends
Also other types of flow meters than turbine meter on the lube oil delivery interval. Generally, the tank is
are used, the design of the flow meter unit is then sized for 28 days consumption or as a minimum, the
different tank should contain a sufficient quantity of lubricat-
ing oil for an oil change in one engine.

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The lube oil tank for used lube oil and the service 3.5.2 Lube oil storage tanks
tank must be able to store oil from at least one en-
gine, plus a 15 % safety margin. According to tank standards, vertical cylindrical tanks
are typically used for volumes >35m3. Smaller tanks
When sizing the pumps, the lube oil quality and vis- are normally horizontal. Large storage tanks are usu-
cosity should be considered. To avoid emulsification ally built on site while smaller ones can be prefabri-
of water, the lube oil pumps should be of screw cated elsewhere.
pump type.
The standard tanks delivered by Wärtsilä are made of
The movements of the engine pistons and the slight steel. Each tank has inlet and outlet connections, a
pressure leakage past the piston rings give rise to drain pipe, a vent pipe, an overflow pipe and a man-
crankcase gases, which may contain lube oil. The hole.
crankcase gases are led to the oil mist separator,
where the lube oil traces are separated out. The con- Vertical tanks have slightly sloping bottoms with wa-
densate is drained back to the oily water system. ter collecting pockets from where the drain tubing is
conducted. The filling pipe inlet is turned to the tank
wall to give a smooth flow. The tanks are equipped
with level switches.

10000
Typical SAE 30
Typical SAE 40

1000
Viscosity (cSt)

100

10

1
0 50 100 150 200
Temperature (°C)

Figure 36. Temperature – viscosity diagram for SAE 30 and SAE 40

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Oil mist separator unit

The oil mist separator unit removes the oil particles
from the crankcase vent gases utilizing the centrifugal
force principle. The separated oil flows back to the
oil sump via the crankcase ventilation pipe. The oil
mist separator is located on the pipe rack.

Figure 37. An example of a vertical tank

If needed, the tanks are equipped with heating coils.

Note that if a tank contains an electrical heating coil,
the level in the tank must always cover the coil to
protect it from overheating.
Figure 39. Oil mist separator (double)

3.5.3 Lube oil pump units

The standard transfer pump unit consists of a suction 3.6 Compressed air systems
filter, one or two electrically driven screw pumps,
valves, and a control panel. To protect the pumps
from over pressure, they are equipped with built on
overflow valves.
3.6.1 System description
General
Compressed air is used to start the engines (starting
air), and as actuating energy in pneumatic safety and
control devices (instrument and control air). Instru-
ment and control air can also be used as “working
air” in diaphragm pumps and in pneumatic tools. The
nominal starting air pressure is 30 bar and minimum
pressure is 15 bar. The instrument air pressure is 7
bar. While starting air is required only during start-up,
instrument air is required for operating the engine
and the compact gas ramp.
Compressed air is produced in compressor units,
generally with automatic pressure control. The air is
stored in compressed air tanks, which serve as buff-
Figure 38. Lube oil pump unit (double pump)
ers. The starting and instrument air units can also be
interconnected, enabling the starting air unit to be
used as back-up for the instrument air unit.
To ensure the functionality of the components in the
control and instrument air system, the air has to be
dry, clean and free from solid particles and oil.

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Starting air quality requirements The starting air compressor is typically dimensioned
to fill the tanks from minimum pressure (15 bar) to
Starting air should be cleaned with an oil and water nominal pressure (30 bar) in one hour. With this
separator. Normally there is no need for a dryer. principle, the required compressor capacity for a 4.4
m3 tank volume would be 4.4 x 15 = 66 Nm3/h at 30
Instrument air quality requirements bar.
The instrument air is to meet the requirements in Instrument air system sizing principles
“Contaminants and purity” class-2.4.3 as per the ISO:
8573.1: 1991 standard. With this, it also meets “Qual- The control and instrument air unit(s) should have
ity standard for Instrument air” by ISA-S7.0.01-1996 sufficient capacity to supply the peak consumption of
with consideration of ambient temperature of min. the plant, even in case of a leakage. The required ca-
13°C. pacity depends on the size of the plant and the type
of installed equipment. Instrument air is consumed at
Maximum particle size: 1 micron
least by the engines, the compact gas ramps, the fuel
Maximum particle concentration: 1 mg/m3 gas shut-off valve(s), and the exhaust gas system ven-
Maximum pressure dew point: + 3°C (37°F) tilation valve. Minimum capacity is typically 1.1
Maximum oil content: 1 mg/m3 Nm3/min for a one engine plant.
Table 9. Instrument air quality requirements In plants with one to three engines, an air receiver of
300 litres/engine and a design pressure of 10 bar is
The strict requirements imposed on instrument air typically recommended. In larger plants, and in plants
make an air filter and drier necessary. In addition, with irregular air consumption, more receivers may
water separators should be installed before instru- be needed. Big consumers, for example soot blowers,
ments that are sensitive to water. may need their own local air receivers.

Starting air system sizing principles

The required capacity of the starting air units, and the
number and size of the starting air tanks depend on
the required start-up time of the plant. The standard
principle is to size the tanks for three start attempts
per engine in small plants, and two starts per engine
in larger plants.

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Figure 40. Compressed air system diagram

3.6.2 Starting air unit

General
Wärtsilä’s standard starting air unit consists of the
following main components mounted on a common
steel frame:

· one or two compressors with a control panel

· an oil and water separator
· a pressure reducer for connection to the control Figure 41. Starting air unit with two compressors
and instrument air system.
Vibration dampers are mounted between the com-
pressor unit and the floor.

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If there are two compressors, one compressor is Air dryer

working while the other one is stand-by. Both com-
pressors may be electrically driven, or one of them The air dryer removes water from the compressed air
may be a diesel driven emergency unit. The air outlets before it leaves the unit. In most cases, a refrigeration
are connected in parallel. For fast production, both dryer gives sufficiently high air quality and is the pre-
compressors may be used simultaneously. ferred type of dryer.

The compressor is of two-stage type with intermedi-

ary air cooling. It is designed for 40 bar maximum 3.6.4 Compressed air tanks
operating pressure and includes a pressure release
valve. The compressor is started and stopped auto- The air receivers are to be equipped with at least one
matically by the signals from a pressure switch. It is manual valve for condensate drainage. Horizontally
started at about 23 bar and stopped at 30 bar. A low mounted air receivers must be inclined 3-5° towards
pressure alarm signal is activated at 18 bar. the drain valve. Being pressure vessels, they must be
tested and stamped for the design pressure according
Oil and water separator to locally valid regulations.
An oil and water separator and a non-return valve are
located in the feed pipe between the compressor and
the starting air receiver.
3.7 Cooling water system
3.6.3 Control and instrument
air unit 3.7.1 System description
Heat removed from the engine must be dissipated
General through an external cooling system – either radiators
or central coolers. Radiators provide a closed system
The standard control and instrument air unit deliv- and require no secondary cooling. With central cool-
ered by Wärtsilä contains the following equipment
ing, a secondary cooling circuit is required with an
built on a common steel frame:
external source of cooling such as a cooling tower or
raw water. The choice of cooling method depends on
· an electrically driven compressor with a control
the ambient conditions, water availability, and envi-
panel
ronmental requirements.
· a compressed air receiver
Cooling water quality requirements
· an air cooled refrigeration dryer
For the required cooling water quality, refer to sec-
· a filter for removal of oil, water and particles tion 12.3. Note that neither sea water nor rain water
can be used. Sea-water would cause severe corrosion
Compressor and deposits. Rain water is unsuitable due to its high
oxygen and carbon dioxide content.
Wärtsilä’s standard control and instrument air com-
pressor is a single-stage air-cooled screw compressor Corrosion inhibitors are always mandatory. Water
designed for a working pressure of 7 bar and maxi- additives may also be required to prevent freezing,
mum pressure of 10 bar. The compressor is equipped deposit formation, or cavitation.
with a suction filter and a suction silencer.
The pressure is controlled automatically by opening
and closing the air intake valve while the compressor
is continuously running. The compressor is stopped
automatically after some time of inactivity.

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If the ambient temperature may drop below 0°C, an high temperature charge air cooler (HT CAC)
anti-freeze agent, generally ethylene glycol must be
added to the outdoor circuits. The required amount low temperature charge air cooler (LT CAC)
depends on the minimum ambient temperature (see
lube oil cooler (LOC).
manufacturer´s instructions). The maximum allowed
glycol content in the LT-circuit is 50%. For a 2-C The cooling water system is split into two independ-
system, the max amount of glycol in the HT circuit is ent circuits, referred to as the LT and HT circuits.
20%.
In a one-circuit (1-C) cooling water system, the LT
Cooling water system configurations circuit includes LT CAC, LOC, and HT CAC, while
the HT circuit (jacket-circuit) only contains jacket
The cooling water system removes excess heat from cooling. LT and jacket circuit water flows are mixed
four main sources of heat in a diesel engine: together outside the engine and cooled by either 1-C
Engine jacket (general term used for a combination radiators or in a central cooler. In a central cooler, the
of cylinder jacket, cylinder head, and turbocharger energy is transferred to a secondary water circuit,
cooling) cooled by cooling towers or directly by raw water.

Figure 42. One-circuit cooling system with mixed cooling

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In a two-circuit (2-C) system, the LT circuit circulates With a 2-C system, the HT circuit needs to be sepa-
water through the LT CAC and the LOC, while the rated by a plate heat exchanger (dump cooler) at cold
HT circuit includes the jacket cooling and HT CAC. ambient conditions which requires glycol contents
The LT and HT circuits are cooled separately in 2-C above 20%. With this configuration, glycol can be
radiators or mixed in a central cooler. The 2-C cool- avoided altogether in the HT circuit, as the heat from
ing water system is mainly preferred in heat recovery the HT circuit is transferred to the LT water inside
applications where high HT outlet temperature is the power plant building. The radiators will have only
needed. one cooling water circuit with this configuration.

Figure 43. Two-circuit cooling system with 2-C radiator

Cooling water temperature control The HT temperature control loop controls the HT
water temperature at the outlet from the engine. The
The performance of the engine relies on a stable and default set point is 85°C in one-circuit systems and
correctly set charge air receiver temperature, which, 91°C in two-circuit systems.
in turn, depends on the cooling water temperatures.
Pre-heating
The temperatures in the HT and LT cooling water
circuits are controlled by two three-way valves. The For pre-heating the engine block before start, there is
valves control the flow through the external cooling a preheating unit in the EAM or CAM. The unit
equipment. heats the HT water to the required temperature be-
fore engine start. In cold climates with ambient tem-
The LT temperature control loop controls the cool- perature below +5°C there shall also be a LT-water
ing water temperature at the inlet to the LT charge air preheating unit.
cooler according to a load-dependent set-point curve
provided by the engine control system. The default
set point range is 36 - 43°C.

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Expansion vessel(s)
Volume changes due to changes in water temperature
are compensated by one or two open type expansion
vessels. The expansion vessels also serve as continu-
ous air venting points.
Expansion vessels are located on an elevated position
in order to provide the cooling water pumps with the
required static pressure (0.5–1.0 bar for HT pump,
depending on engine type).

Engine LT/2-C [m] HT/2-C [m]

Figure 44. Air flow through a radiator (horizontal
W18V50SG 0,0 10,0 induced draft, one-circuit type)
Table 10. Required elevation of expansion vessels
Sizing radiator systems
In two-circuit systems, as well as one-circuit systems
with jacket cooling, where the static pressure devel- The size of the radiators and the number of radiators
oped by elevated location may not be sufficient for per engine depend on the ambient conditions and
the HT pump, a pressure increasing pump may be required heat transfer. Normal amount of radiators
required. are 4 – 5 per engine. The dimensions are around 10 –
12 m long and 2,5 m wide per radiators, but this var-
ies depending on design conditions and manufactur-
3.7.2 Radiators ers.

In radiators, fans draw air through a tube bundle The radiators are sized for a certain temperature dif-
where the cooling water flows in one or two closed ference between ambient air and water. The ambient
circuits. air temperature to be used for the LT circuit is the
maximum ambient temperature, but no higher than
Radiators must be installed outdoors with a suffi- the temperature at which de-rating starts. The tem-
ciently large space around to allow for adequate air perature to be used for sizing HT radiator sections in
flow (see Figure 100 and Figure 101 on page 108). two-circuit systems is the maximum ambient tem-
The primary design parameters are the heat load and perature.
the ambient conditions. In addition, possible noise
emission limitations, corrosive environment, high site The heat transfer area must be increased if glycol is
altitude, and glycol content of the cooling water can used in the cooling water, and the supplier must thus
have a significant impact on the radiator size and de- be informed about the glycol content in the cooling
sign. water.

Radiator design Radiator arrangements

The recommended radiator type is the horizontal If multiple radiators are installed, it is recommended
type with induced draft and direct-driven fans. to group them tightly in order to minimize recircula-
tion of hot air between the radiators. When the radia-
The radiators can be of one or two-circuit type. The tors are installed on the roof, gaps remaining between
two-circuit radiators have one LT and one HT circuit adjacent radiators should be covered. The radiators
in the same body but with independent and separated should be installed at such a height that the vertical
heat transfer areas. The standard radiators have cop- air inlet area equals or exceeds the radiator footprint
per tubes equipped with aluminium fins. area, however, not lower than 2 metres above
ground.

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Noise emission considerations Central cooler design

The noise from the radiator field depends on the A central cooler is a plate type heat exchanger, which
number of fans and the rotational speed. Emissions can be installed either inside the engine hall or out-
can be lowered by selecting a radiator with larger heat doors. In one-circuit systems, only the LT circuit is
transfer surface area and fans with lower rotational cooled in the central cooler. In two-circuit systems,
speed. the HT and LT circuits are normally combined and
cooled in one common central cooler.
Standard radiators are available with three different
noise classes, standard noise, low noise and ultra low If raw water is used in the secondary cooling circuit,
noise. The A-weighted sound pressure levels per ra- the cooler will be exposed to fouling. Fouling can be
diator, measured at a distance of 40 m, for the differ- reduced by keeping the water temperature low and by
ent noise classes is shown in Table 11. using softened or treated water. Since fouling cannot
be completely avoided, heat exchangers allowing
Standard noise radiators cleaning should be used.

The sound power levels presented in Table 11 corre- Cooling towers

spond to A-weighted sound pressure levels of 61/64
dB(A) (50/60 Hz) per radiator at 40 metres’ distance. The cooling effect of a cooling tower is based on the
evaporation of water. The heated water from the sec-
Noise class Frequency Noise level ondary circuit of a central cooler is lead to the top of
50 Hz 61 dB(A) the cooling tower and injected through nozzles. The
Standard noise
60 Hz 64 dB(A) water is cooled by evaporation of part of the water in
Low noise 50/60 Hz 56 dB(A) the upward air flow, and then pumped back to the
Ultra low noise 50/60 Hz 49 dB(A) central cooler.
Table 11. Radiator noise levels The water losses in a cooling tower are primarily
caused by evaporation and bleed off. Bleed off is
Using frequency converters necessary to prevent the build up of impurities and
high salt concentration. When designing cooling tow-
By controlling the fan operation using variable speed ers, care should be taken to allow for replenishment
drives, a considerable reduction of average noise level of fresh water.
and power consumption can be obtained when the
ambient temperature and cooling requirements allow. Cooling towers must be installed outdoors with a
The frequency converters are sized for the current sufficiently large space around.
required by the load, and the required spare capacity
(typically 5–10%). Raw water systems
If raw water from sea, river, or lake of suitable quality
is available close enough to the power plant, it can be
3.7.3 Central coolers used in the secondary circuit of the central cooler.
The water has to be filtered and cleaned before use.
General
Raw water intake and discharge systems should be
In a central cooler, the engine cooling water is cooled designed to avoid blockage during all operating con-
by a secondary cooling circuit, which may be raw wa- ditions, to reduce biological growth in the cooling
ter or water cooled in cooling towers. Cooling towers system, and to be in accordance with local rules and
are needed if raw water of suitable quality is not avail- regulations for water usage and discharge.
able, or if it is not permissible to discharge heated
water. Cooling towers are not recommended in instal-
lations where the ambient temperature may fall below
5 °C.

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Wärtsilä 50SG Power Plant Product Guide 3. ENGINE AUXILIARY SYSTEMS

3.7.4 Maintenance water tank The recommended number of tanks is one tank for
every 6 engines. If the glycol content differs between
General the LT and HT circuit, the amount of tanks should
be doubled. This prevents mixing of cooling water
The maintenance water tank is used for retrieving and with different glycol content during maintenance.
storing the cooling system water while the engine is
drained for maintenance work. Clean water and
chemicals can be added in the tank and mixed by cir-
culating the tank content. A pump is needed for emp-
tying and filling the cooling water circuits.

Figure 45. Maintenance water tank

Tank design
The maintenance water tank unit consists of a steel
tank with an electric pump. The tank has connections
for filling fresh water, emptying and filling the cool-
ing water system, a drain valve, and a vent/overflow
pipe.

Sizing maintenance water tanks

The maintenance water tank should be sized to store
the entire water volume in the HT and LT cooling
water systems of one engine, including the engine
itself and components such as pre-heater, expansion
vessels, and heat exchangers. The tank is also de-
signed to contain the water volume of the external
piping system and the radiators, although these are
normally drained separately. If the tank is equipped
with a secondary containment for leakage collection,
the containment should be sized to hold the total
volume of the tank.

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3.8 Intake air system Air filtration requirements

The highest permissible dust concentration at the
turbocharger inlet after filtration is 3 mg/m3, and the
3.8.1 System description filter should be able to separate 70% of particles
above 5 mm. The highest allowable concentration of
General harmful components in the engine intake air after
filtration is shown in
The main function of the charge air system is to pro-
vide the engine with an adequate supply of clean and Other air quality requirements
dry air. The air is drawn into the turbocharger com-
pressor side through the charge air filter and silencer, Component Maximum value
from where the air is pushed into the charge air
Sulphur Dioxide (SO2) 1.25 mg/Nm3 or 0.43 vol-ppm
cooler and then into the charge air receiver for the
engine. Hydrogen Sulphide (H2S) 375 μg/Nm3 or 0.25 vol-ppm
Chlorides (Cl-) 1.5 mg/Nm3 or 1.16 mass-ppm
The charge air temperature is controlled using the Ammonia (NH3) 94 μ/Nm3 or 0.125 vol-ppm
cooling circuits. The charge air cooler usually has two
stages of cooling. The first stage uses HT cooling Table 12. Maximum content of chemicals
water, and the second (final) stage uses LT cooling
water. Temperature requirements
System design Too high inlet air temperature will cause an excessive
thermal load on the engine and requires the engine to
The external charge air system consists of Charge air be de-rated, and cold suction air with a high density
filter, Charge air preheating coils and charge air si- will cause high firing pressures.
lencers. The internal system consists of LT & HT
charge air coolers. The following graph illustrates minimum continuous
intake air temperature as a function of the load.
The design of the intake air system depends on the Temporary operation below the minimum tempera-
ambient temperature, altitude, particle content in the ture is possible.
ambient air, and noise level allowed outside the plant.
Possible extreme conditions, such as sand storms,
snow storms, and heavy rain must also be considered.
Combustion air to the engine is generally taken from
outdoors through an intake air filter. Air filtration is
required to protect the turbochargers and to remove
particles in the air that may cause deposit formations
or damage the engine.
When measuring the concentration of dust and
chemicals in the air, the worst scenario should be
taken into account. A detailed investigation of the air
filtration must be done in areas where the air includes
caustic, corrosive or toxic components.
Figure 46. Minimum continuous air temperature
before the turbocharger at different
loads

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By preheating the LT water, the engine can be started

at combustion air temperatures below 5oC. An LT
pre-heater can be included in the EAM module.
Other solutions for starting as well as operating the
engine at low ambient air temperatures are:
Taking the intake air from the engine hall
Heating the intake air, for instance, with electrical
coils or by using heat recovered from the engine
cooling circuits.

Air humidity
At high ambient air humidity, the high pressure in the
charge air system (about 3.5 bar(a) at 100 % load)
can cause the airborne humidity to condensate at
normal charge air temperatures. In these cases, the Figure 47. Dew point temperature curve at 3.5
charge air temperature should be raised in order to bar(a)
avoid corrosion of the charge air cooler and intake
valves. See the dew point temperature curve in Figure
Pressures and flows
47. De-rating of the engine may be necessary due to
the increased temperature. Maximum allowed pressure drop in the intake air sys-
tem up to the turbochargers, including pipes, filters
and silencers, is 2000 Pa. The system should prefera-
bly be designed to not exceed half the limit at full
load. The air flow depends on the air temperature and
the altitude.

Noise
The charge air sound pressure level at the turbo-
charger inlet is typically 120 dB(A) and very high fre-
quency distributed. To dampen the noise, charge air
silencers should be installed.

EXHAUST GAS MODULE Turbocharger ENGINE

Exhaust gases

Intake air filter Intake air

Intake air silencers Intake air coolers

Intake air

Exhaust gases
Turbocharger

Figure 48. Typical combustion air system

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In some cases, dry type filters (EN 779 filter class

M5) are suitable. Oil wetted filters are suitable in ar-
3.8.2 Intake air filters eas with higher dust load and coarse particles. In
these cases, the oil wetted filter (EN 779 class
Filter types G2/G3) is to be combined with a secondary dry filter
The following filter types are most commonly used: (EN 779 class M5).
In desert conditions, jet pulse filters or other self
· Combined oil wetted and dry filters. The com- cleaning solutions are recommended.
bined oil wetted and dry filters have a moving
screen which is washed in an oil bath at the bot-
tom of the filter. After the oil wetted filter section
Lovers and hoods
there is a second filter step, usually realized with The air intakes shall be protected from heavy rain,
dry filter elements snow, insects, etc. The standard intake air filters used
· Dry type filters. These filters are static filters with by Wärtsilä include a vertical weather louver which
filter elements which must be regularly replaced. removes most water droplets. Usually also a rain
hood is used to secure the operation.
· Jet pulse filter. Self cleaning filters

Figure 49. Dry type charge air filter

Figure 51. Intake air filter with rain hood (example)

Ice prevention
Ice on the intake air filter can result in a very high
pressure drop in the charge air system and trip the
engine. Ice may be formed if the air temperature
drops below the dew point and the surface tempera-
ture is at or below the freezing point. The critical
temperature range is -5ºC to +3ºC. Ice formation can
be avoided with heating arrangements.

Instrumentation
Figure 50. Cutaway of an oil wetted filter The intake air filter should always be equipped with a
differential pressure alarm. Oil wetted filters has also
a movement sensor alarm. Jet pulse filters are sup-
plied with an independent control system.

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Wärtsilä 50SG Power Plant Product Guide 3. ENGINE AUXILIARY SYSTEMS

3.9 Exhaust gas system Safety arrangements

In case of a malfunction or incomplete combustion,
the exhaust gas may contain unburned components,
3.9.1 System description which may ignite upon contact with hot surfaces. The
resulting deflagration may cause damage to the ex-
General haust gas system and personnel. Unburned gas in the
exhaust gases may also damage a catalytic converter,
The main function of the exhaust gas system is to if installed.
lead exhaust gases safely out from the power plant.
Each engine must have its own exhaust gas system. The following protection methods are required:
The main components besides the ducts are an ex-
haust gas silencer, an exhaust gas stack, and safety · Minimizing the risk of gas build-up by designing
equipment, such as an exhaust gas ventilation fan and the pipe system with only upward slopes
rupture disks.
· Ventilating the exhaust gas system to discharge
any unburned gas after the engine has stopped
Design pressures
· Relieving the pressure at a possible deflagration
Allowed maximum back pressure at the outlet of the with rupture disks.
turbochargers is 5000 Pa (0.05 bar). However, the
system components shall be capable of tolerating The exhaust gas ventilation system consists of a cen-
higher pressure due to the risk for exhaust gas defla- trifugal fan, a flow switch and a butterfly valve. The
grations. Thus, the design pressure for the exhaust valve is opened and the fan started after each engine
gas system is minimum 0.1 bar(g), and the system stop. The flow switch monitors the fan operation and
must be able to sustain 0.5 bar(g) peak pressure for at activates an alarm in case of a malfunction. The fan is
least one second. designed to change the volume in the exhaust gas
system at least three times during a ventilation run.
Due to gas velocities created by a possible gas defla-
gration, under-pressure (partial vacuum) may occur.
Therefore, the stack must be sized to sustain an un-
der pressure of 0.3 bar without collapse.
Stack
Exhaust gas silencer

Rupture Rupture
disk disk
EXHAUST GAS Turbocharger ENGINE
MODULE Exhaust gases

Boiler SCR Exhaust gas

ventilation fan
Intake air coolers

Drain

Exhaust gases
Turbocharger
Drain

Figure 52. Typical exhaust gas system

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Wärtsilä 50SG Power Plant Product Guide 3. ENGINE AUXILIARY SYSTEMS

Exhaust gas boilers can be equipped with integrated

rupture disks, or the rupture disks can be located in
3.9.2 Exhaust gas silencers the exhaust duct close to the inlet and outlet pipes of
The exhaust gas silencers must be effectively purged the boiler. Catalytic converters installed in the exhaust
during the exhaust gas system ventilation. Silencers of gas system, should be fitted with rupture disks in a
absorption, reactive or combination type can be used. similar way.
The required attenuation of the silencers is deter-
mined by the environmental noise requirements. Outlet ducts
The standard exhaust gas silencers delivered by Wärt- The outlets of the rupture disks are to be ducted out-
silä are of combination type, giving a noise attenua- doors with pipes of the same size as the rupture
tion of 35 dB(A) or 45 dB(A). The silencers are pro- disks. The length of the duct should be minimized
vided with a water drain. A soot collector and a spark and not longer than six meters. In cold snowy areas
arrestor are optional. the duct shall covered with weather protection. The
outlets should be placed where no personnel are pre-
The exhaust gas silencers can be mounted either sent during plant operation. A 10 m wide and 10 m
horizontally or vertically, inside or outside the build- long zone continued in the direction of the outlet
ing. Generally, they are installed in the stack. duct must be marked as a hazardous, possibly lethal
zone.

3.9.3 Rupture disks

Design
Rupture disks are the only approved pressure relief
devices. The rupture disks shall be designed to open
at an excess pressure of 0.5 ± 0.05 bar at the operat-
ing temperature. Spring loaded devices are not al-
lowed to be used.
The diameter of the rupture disks should be the same
as the exhaust gas pipe diameter. The disks must be
installed directly in the main duct.

Location of rupture disks

On a straight pipe, the rupture disks shall be installed
Figure 53. Rupture disk danger zone
at a distance of maximum ten pipe diameters apart,
disks with smaller diameter than the duct will be
placed closer together. The first rupture disk is to be
placed within 5 to 10 meters after the turbocharger
and so arranged that material from the rupture disk
will not fall into the turbocharger. The rupture disks
must not be exposed to dynamic pressure pulses.
The inlet and outlet of the silencer shall be equipped
with rupture disks, but the rupture disk in the inlet
may be omitted if the distance from the previous disk
is less than 5 times the pipe diameter. If the silencer is
the last component in the piping before the stack, the
outlet needs not be protected with a rupture disk.

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Wärtsilä 50SG Power Plant Product Guide 3. ENGINE AUXILIARY SYSTEMS

3.10 Emission control Performance

systems The performance of the catalyst depends on the size

and composition of the catalyst. The performance
demand is set by the project-specific requirements.
VOC (Volatile Organic Compounds) is defined to be
3.10.1 General NMNEHC (non-methane non-ethane hydrocarbons)
in the following table.
If required by local environmental regulations secon-
dary emission control equipment can be installed.
Compound Unit IOXI ULE
SCR is rarely used today for gas engine applications;
only in bigger plants or/and if ambient air is de- CO ppm-v, 89 15
graded, the SCR unit is typically demanded. Carbon 15 % O2,
monoxide dry
Emissions of Carbon Monoxide (CO), Formaldehyde CH2O ppm-v, 17 <5
(CH2O) and Volatile Organic Compounds (VOC) are (formaldehyde) 15 % O2,
typically controlled using an oxidation catalyst. The dry
recommended secondary method for reducing the VOC ppm-v, 15 Low 20 … 40
NOx emissions of a lean burn gas engine is Selective (volatile organic % O2, dry, reduc- Depends
Catalytic Reduction (SCR). components) as CH4 tion strongly on
natural gas
composition
Table 13. Typical emission levels achieved for gas
3.10.2 Oxidation catalyst engines with oxidation catalyst

Functional description
Using the oxidation catalyst, carbon monoxide (CO), 3.10.3 Selective catalytic re-
formaldehyde (CH2O), and volatile organic com- duction (SCR)
pounds (VOC) are oxidized to carbon dioxide and
water according to the following simplified formulas: Functional description
CO + O2 ® CO2 In the selective catalytic reduction (SCR) method,
CmHn + O2 ® CO2 + H2O NOx reacts with ammonia (NH3) forming water and
CmHnO + O2 ® CO2 + H2O atmospheric nitrogen according to the following sim-
plified formula:
The reactions take place on the surface of the cata-
lyst, the function of which is to reduce the activation NOx + NH3 ® N2 + H2O
energy required for the oxidization reaction. No re-
agents are needed, that is, no consumables are re- The reaction takes place on the surface of a catalyst in
quired, and no by-products are formed. the presence of a reducing agent, which is injected
into the flue gas before the catalyst. For the reducing
The catalyst is optimized by choosing the correct ac- agent, aqueous ammonia or aqueous urea of technical
tive material, substrate and wash coat. The active ma- quality can be used. When urea is used, it decom-
terial is typically a noble metal such as platinum (Pt), poses to ammonia (NH3) in the flue gas. The reduc-
or palladium (Pd), or a combination of them. ing agent can also be prepared from urea granulates
of technical quality by mixing granulates with demin-
eralised water at site.
Due to the hazardous and explosive nature of am-
monia, urea solution often is preferred.

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Wärtsilä 50SG Power Plant Product Guide 3. ENGINE AUXILIARY SYSTEMS

Performance The reagent solution is sprayed into the flue gas with
a dosing unit using compressed air to achieve a
A SCR system is often designed for 90 % NOx emis- good atomization.
sion reduction, i.e. the level of less than 10 ppm, dry,
15 % O2 is reachable in stable running conditions. A mixing duct ensures that the reducing agent is
completely vaporized and mixed with the exhaust gas.
Main components In the first section of the duct, the reducing agent will
vaporize, and if urea is used it will decompose to
The catalysts are installed in a reactor designed ac- ammonia (NH3). The second section is equipped with
cording to the project requirements. The SCR catalyst static mixers to ensure a homogeneous distribution of
typically consists of honeycomb blocks of ceramic NH3.
material arranged in layers. If the emission control
system includes oxidation catalysts, the oxidation
catalyst elements are typically located in the SCR re-
actor, downstream of the SCR elements.

Figure 54. Typical SCR emission control system setup for gas engine applications

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Wärtsilä 50SG Power Plant Product Guide 3. ENGINE AUXILIARY SYSTEMS

Consumables 3.10.4 Integration in exhaust

The consumption of the reducing agent depends on
gas system
the NOx emission level from the engine and the tar-
get level. Operating conditions may also influence the Placement
consumption of the reducing agent. When using SCR, The SCR and the oxidation catalyst should be located
it is generally more economic to tune the engine for before a possible heat recovery system and before any
optimal heat rate instead of low NOx emission. exhaust gas silencer containing wool. The oxidation
An indicative value for reducing agent consumption catalyst must not be placed between the reducing
for one W18V50SG engine is 33 - 55 kg/h (25 % agent injection point and the SCR reactor.
ammonia water or 40 % urea water). The ammonia or
urea must be of at least technical grade. Space requirements

Typically, the useful lifetime of the SCR catalyst ele- The required space depends on the emission reduc-
ments is several years. The possibility to replace indi- tion requirements and the design of the emission
vidual catalyst layers enables the development of an control system. The compact oxidation catalysts for
optimal catalyst exchange strategy. low emission reduction demands can be integrated in
the exhaust gas duct with negligible impact on the
Storage of reducing agents plant layout while the big combined SCR oxidation
catalyst reactors might have a length up to 6 meters
For gas engine applications ammonia or urea is typi- or even more.
cally brought to site as a readymade water solution.
The tank material for urea solutions is often stainless Special attention should be put on having sufficient
steel tanks while black steel tanks (DIN – ST37-2 or space for the mixing duct in case a SCR system is
better) can be used for aqueous ammonia solutions. required. In systems where the oxidation catalyst is
If there is a risk for freezing or precipitation of urea integrated into the SCR, the catalyst elements are
solution (depends on the concentration and the tem- placed as an additional layer in the reactor.
perature), the tanks must be insulated and either
heated or equipped with a circulation system. Atten- Temperatures and pressures
tion must be paid to the safety issues related to the The SCR and oxidation catalyst have a temperature
handling of ammonia. window for optimal operation. The normal operating
The storage space is typically sized for two weeks’ temperature of the W50SG engine fits well with the
consumption. In addition, the size of one truck load typical operating windows. The efficiency of the oxi-
must be taken into account. dation catalyst increases with higher exhaust gas tem-
perature.
Control and instrumentation The design pressure for the catalysts is minimum 0.1
There may be one control unit per engine, or a unit bar(g), but they shall be capable of tolerating 0.5
can control the emissions from several engines. The bar(g) peak pressure.
local control panels can be located e.g. in the engine Typically, the emission control system creates a back
hall or in the control room. The control unit calcu- pressure of maximum 2000 to 3000 Pa.
lates the set point to the reducing agent dosing unit
by using feed forward control (based on the engine
load), and feedback control (if analyzer(s) are pro-
vided in the system; based on the NOx measure-
ments).

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Wärtsilä 50SG Power Plant Product Guide 3. ENGINE AUXILIARY SYSTEMS

3.10.1 Emission testing In Table 14 typical requirements are depicted as ex-

amples for gas fired engines in some countries and by
Emission tests and measurements are an integral part International Finance Corporation (IFC, a part of the
of the performance testing and the environmental World Bank Group). The IFC Guidelines are more
management of the power plant. Emission tests for and more commonly applied for power generation
commissioning and reporting purposes are typically projects, in which international financing or export
performed by impartial emission testing consultants. credits is given.
The source testing should be performed using meth-
ods that are proven for gas engine applications. The Note that the limits below are given on the federal
common parameters for the emission tests of gas level. Local requirements, ambient air quality or other
fired units are NOx, CO and O2. In some cases hy- project-specific issues might call for more stringent
drocarbons are to be tested according to the national requirements. Note also that the values are converted
requirements. to the same units and reference oxygen conditions for
comparison purposes.
Sampling ports and access to the sampling location
must be part of the of the exhaust gas system design.
If specifically required by authorities, a continuous
emission monitoring system (CEMS) can be installed.
For gas engine plants, the monitored parameters are
typically NOx, CO and O2. Other components are
either not present in relevant concentrations in the
exhaust gas, or they cannot be monitored due to the
lack of proven monitoring methods.

Germany, Denmark, Turkey, IFC,

TA Luft 2002 1998 2004 2007(d, 2008(e

NOx Emissions, ppm 90 100 90(b 97

CO Emissions, ppm 89 150 193(b -

HC Emissions, ppm 17 for formaldehyde 1050 as THC (as C1)(a - -

6 for formaldehyde(a

PM emissions, mg/m3 (c 49(b -

SO2 Emissions, ppm - - 8(b -

Wärtsilä solution Oxidation catalyst Oxidation catalyst No secondary control No secondary control
a) Efficiency correction based on the reference efficiency of 30% à Limit = efficiency
Notes
%/30*base limit
b) Efficiency correction based on the reference efficiency of 37% (no cogeneration) or 63%
(with cogeneration) à Limit = efficiency %/reference efficiency*base limit
c) Normalized to 0°C and 101.3 kPa
d) International Finance Institute, General EHS Guidelines, plants 3-50 MWth
e) International Finance Institute, Thermal Power EHS Guidelines, plants >50MWth
Table 14. Emission limits for spark ignited lean burn gas engines (dry at 15% O2)

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Wärtsilä 50SG Power Plant Product Guide 4. HEAT RECOVERY SYSTEM

4. HEAT RECOVERY SYSTEM

Heated media Generator Recoverable

4.1 General power heat (±5%)
Steam 8 bar(a) 18321 kW 6800 kW
Hot water 18321 kW 14500 kW
Heat recovery systems utilize the heat generated by
70 – 95 °C
the engine which would otherwise be wasted. Heat
can be recovered from the exhaust gases and from Hot water 18321 kW 15800 kW
the engine cooling system (charge air, lubricating oil, 55 - 95 °C
and jacket cooling). The following table gives a rough Hot water 18321 kW 6550 kW
indication of the temperatures of the engine circuits 45 - 75 °C
and the available energy amounts. (no heat recovery from
exhaust gases)

Energy source Temperature Portion of fuel

Table 16. Typical values for different types of heat
(approx.) energy carrying media. Except for the last row
(approx.) the values apply when heat is recovered
from both exhaust gases and cooling
Exhaust gas ~ 375 °C 30,1 % water.
Jacket water ~ 82 °C 4,8 %
HT charge air ~ 96 °C 9,2 %
Lubricating oil ~ 74 °C 3,6 %
LT charge air ~ 43 °C 4,1 % 4.2 Heat recovery from ex-
Generator cooling
Table 15.
~ 35 °C
Different energy sources
1,2 %
haust gases

The heat is normally used to produce hot water, 4.2.1 System description
steam or thermal oil. The amount of recovered heat
depends on the ambient temperature and the tem- A typical exhaust gas heat recovery system for steam
perature of the heated media. The following table production consists of an exhaust gas boiler, a steam
shows typical values for steam and hot water when drum, one or more pumps and one or more water
utilizing heat from exhaust gases, lubricating oil and tanks. On the consumption side, there is a steam
cooling water from a W18V50SG engine. header and one or more heat exchangers.
The exhaust gas steam boiler contains evaporator
pipes, where the feed water is heated to its saturation
point. The mixture of saturated water and steam is
lead to the steam drum, where steam is separated
from water. The steam drum is typically integrated in
the boiler. The boilers should be equipped with an
exhaust gas by-pass line for capacity control and to
avoid boiler overheating on the water side.
The steam can be further heated in a super-heater, or
conducted to the consumers. The condensate from
the consumers is normally circulated back to the
boiler via a condensate water tank.

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Wärtsilä 50SG Power Plant Product Guide 4. HEAT RECOVERY SYSTEM

The feed water tank, the feed water pumps, and the 4.2.2 Heat recovery boiler
condensate return tank are usually common for the
whole plant. The steam boilers are engine specific. Heat recovery boilers are heat exchangers, where the
exhaust gas transfers some of its thermal energy to
the heat transfer media, most commonly water. Typi-
cally full capacity boilers are used to maximize the
heat recovery from the exhaust gases.
The boilers can be divided into two groups:

· Smoke tube boilers, where the exhaust gas flows

through pipes surrounded by water
· Water tube boilers, where the exhaust gas flows
around finned tubes in which water circulates.
The choice of boiler type depends on many factors,
e.g. the heat recovery application that is being used.
The energy recovered depends directly on the
Figure 55. A simplified example of steam produc- amount of exhaust gas and the temperature drop
tion in an exhaust gas boiler across the boiler. In steam production, the tempera-
ture is limited by the steam saturation temperature.
In order to intensify the heat recovery and improve The pinch point (minimum temperature difference
the efficiency, the boiler can be equipped with an between heating and heated media) is the difference
economiser for pre-heating the water. between the saturation temperature and the exhaust
gas temperature at the outlet of the evaporation sec-
If the steam drum is located higher than the boiler, tion.
no circulation pump is needed (natural circulation
boiler). Otherwise, there must be a circulation pump
(forced circulation boiler). 4.2.3 Arrangements to de-
To avoid corrosion in the pipes, steam systems must crease boiler fouling
be equipped with deaeration, and the feed water tem- A common phenomenon with exhaust gas boilers is
perature should be at least 105oC. boiler fouling. It is caused by soot, unburned hydro-
In district heating and warm water applications, there carbons, lubrication oil residues, etc. which comes
is only a hot water boiler with an exhaust gas by-pass with the exhaust gases and forms layers on the heat
line and a main water pump. Also in this application exchanger surfaces. This results in reduced and in-
an economizer can be added to improve the heat re- efficient heat transfer. The fouling rate depends on
covery. the temperature. The most critical area is on heat
transfer surfaces, where the water side temperature is
The design pressure on the exhaust gas side is mini- 50 - 80°C.
mum 0.07 bar(g), but the system must be capable of
tolerating a peak pressure of 0.5 bar(g). Methods to decrease the fouling rate and keep the
boiler clean involve:
Due to gas velocities created by a possible gas defla-
gration, under-pressure (partial vacuum) may occur. · Avoiding water temperatures between 50 and 80
Therefore, the stack must be sized to sustain an un- °C
der pressure of 0.3 bar without collapse.
· Using soot blowing equipment (for instance, wa-
ter spray, pressurized air or steam blowers)
· Using Oxi-Catalyst (HC)

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Wärtsilä 50SG Power Plant Product Guide 4. HEAT RECOVERY SYSTEM

Off-line cleaning is needed periodically, typically two For hot water applications with heat recovery from
to four times a year. both lube oil and HT water, two types of heat recov-
ery options are mainly used. One more efficient
used for lower return water temperatures, and the
4.2.4 Safety valves in the other with better dump cooling properties used
together with higher return water temperatures, and
steam / water system in cases where the heat power is from time to time
The heat recovery boiler should be protected with reduced.
rupture disks installed in the exhaust gas duct before Both applications have an optional dump cooling so
and after the boiler. In some cases, there might be
the engines can run when the heat recovery need is
additional explosion vents in the boiler casing.
reduced.
The heat recovery boiler should be designed accord-
In the more efficient application the incoming hot
ing to applicable rules and regulations. water/DH water temperature is controlled so the
temperature before the jacket cooling is kept at 75°C
In the application with better cooling properties each
4.3 Heat recovery from cooling circuit has its own dump cooler. In both con-
cepts the on the engine built LO cooler is used for
cooling water and lube back up cooling of LO and in both cases there is a
by-pass line for the LO heat recovery heat exchanger
oil so too much cooling of LO can be avoided.

4.3.1 General
Heat for hot water production can be recovered from
the HT CAC, jacket cooling water and from the lube
oil.

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Wärtsilä 50SG Power Plant Product Guide 4. HEAT RECOVERY SYSTEM

Exhaust gas

District heat

LT Cooling water

HT Back-
Exhaust Radiator up cooler
gas boiler (optional) Lubricating oil

HT cooling water

Lube oil Back-

up cooler
HT Water heat
Stack
exchanger
LT CAC

Hot water
system
HT CAC

Lubricating oil
Lube oil cooler

CHP Connection (example) EAM Engine

Figure 56. Typical arrangement of combined lube oil, cooling water and exhaust gas heat recovery us-
ing a CHP connection for lower return water temperatures.

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Wärtsilä 50SG Power Plant Product Guide 4. HEAT RECOVERY SYSTEM

4.4 Flexicycle™ power The Flexicycle power plant is mainly intended

for based load and intermediate load in the plant
plant range of 100-500 MW, even in hot conditions
and at high altitude.
The closed circuit system delivers superheated
4.4.1 System description steam to a steam turbine, and the steam is con-
densated in a steam condenser before returned
A Flexicycle power plant is combining the to the boiler system.
W18V50SG gas cycle mode with a steam cycle.
This brings the capability to switch between
combined cycle mode and simple cycle individu-
ally for each generating set.

Figure 57. Flexicycle process with steam preheating of the engines

The boilers are equipped with a steam drum,

4.4.2 Main equipment where feed water is lead from the exhaust gas
boiler economizer. The water is evaporated in
Heat recovery steam generator/ Exhaust the HP evaporator part of the boiler, and the
gas boiler saturated steam from the steam drum is finally
superheated. The steam drum is equipped with
Steam is produced in vertical exhaust gas boilers, built-in water/steam separation in order to pro-
one per engine by recovering waste heat energy vide the superheater with steam. To avoid over-
from the exhaust gas flow. An exhaust gas or under pressure in the steam drum, the water
damper is used to direct the exhaust gas flow level is controlled by a level controller con-
through the boiler, or through the by-pass duct. nected to valves in the feed water pipe.

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Wärtsilä 50SG Power Plant Product Guide 4. HEAT RECOVERY SYSTEM

Steam header Condenser cooling system

High-pressure steam headers are used to collect The power plant cooling is typically arranged so
superheated steam from the boilers and lead it that the combustion engines are cooled with
to the steam turbine. Superheated steam from all closed loop radiators, and the steam cycle
boilers is collected to high pressure steam through evaporation of water in cooling towers.
header(s). The exhaust gas boilers are connected Returning water from the condenser is pumped
to single high pressure steam header(s) and the to the upper part of a cooling tower, where it is
steam lines from the high pressure steam head- sprayed through nozzles. The water is cooled by
ers are connected before the turbine inlet. the upward air flow, and then pumped back to
the condenser. Cooling towers and cooling wa-
The steam system must be equipped with ter pumps are equipped with frequency convert-
deaeration to avoid corrosion in the steam and ers to control the fan speed and pump capacity.
condensate piping.
Air cooled condenser is a possible option in-
During start up of the plant the header is used stead of cooling towers if no water is available.
for boiler steam blow-out until the steam
achieves the required temperature and can be Condensate preheater
connected to the steam turbine
Before the condensate is returned to the feed
Steam turbine-generator and condenser water tank it is preheated by engine HT water in
a plate heat exchanger.
The produced high pressure steam is utilized for
additional electricity production in a common Heat recovery container
steam turbine and generator set. A gear box be-
tween the turbine and the generator is used to An auxiliary boiler is used during start up when
lower the steam turbine rotating speed. The tur- the low pressure steam produced by the exhaust
bine is equipped with a condenser. gas boiler is not enough for the own consump-
tion of the power plant.
During start-up and in case of turbine trip or
shut-down, the steam can be directed to the The auxiliary boiler is placed inside a heat recov-
condenser with a by-pass valve in the steam ery container including all auxiliary equipment.
dumping system The burner for the boiler can be operated with
either HFO/LFO or Gas. A feed water pump
The condenser creates partial vacuum by con- unit in the container is used to pump water from
densating steam from the turbine. A vacuum the feed water tank to the auxiliary boiler at the
unit is connected to the condenser in order to appropriate pressure.
remove incondensable gases like air. By having
vacuum in the condenser and thus allowing Feed water tank
steam to expand below atmospheric pressure,
the enthalpy difference between the turbine inlet Condensate is returned to a common feed water
and outlet allows for more efficient conversion tank from the steam turbine system and from
of heat to mechanical energy. The quality of the the plant’s own consumption. Other incoming
steam after the condenser is monitored. flows to the feed water tank are make-up water,
minimum flows from feed water pump units,
Condensate from the condenser is pumped back heating steam line from low pressure header,
to the feed water tank by condensate pumps. and return flow from low pressure evaporator
The water level in the condenser is maintained (exhaust gas boiler) The feed water tank is
by control valves. equipped with deaeration.

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Wärtsilä 50SG Power Plant Product Guide 4. HEAT RECOVERY SYSTEM

Superheated steam
from other boilers

Superheated steam Electric power

G
Superheater Steam turbine
Steam header

HP-evaporator HP Steam drum

Cooling
Economizer tower

Condensate pump
Cooling water
HT Water heat recovery pump
LP-evaporator

Make-up water

Exhaust
gas boiler Feed water tank

Feed water

Feed water pump

Exhaust gas

Figure 58. A simplified example of steam production for a steam turbine.

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Wärtsilä 50SG Power Plant Product Guide 5. PIPING SYSTEMS

5. PIPING SYSTEMS

5.1.2 Pressure and tempera-

5.1 Design principles ture ratings
Design pressures
5.1.1 General principles
For estimating the design pressure, the following rule
The following general principles should be consid- of thumb can be used:
ered in the piping system design:
design pressure = 1.1 x max. working pressure
· The pipes must be designed for the maximum and
minimum pressures and temperatures they will The maximum working pressure in a circuit is equal
to the setting of the safety valves in the system.
experience during operation or upset conditions.
· The risk for pump cavitation – the formation of Nominal pressures
bubbles at the suction side of the pump, which
reduces pump efficiency and harms the pump – The nominal pressure of a pipe should be equal to or
must be minimized. The suction pipes to pumps higher than the design pressure of the pipe.
should be as short as possible and have suffi- According to European standards, the pressure rat-
ciently large diameters. ings of piping systems are given as PN numbers
· The pipes must be fitted without tension. Flexible (Pressure Nominal), for instance, PN6, PN10, PN16,
pipe connections must be used between pipes and where the number indicates the nominal pressure in
units where vibrations or thermal expansion may bar up to a given maximum temperature.
occur. The nominal pressures of the pipe connections on
· Each pipe must have sufficient pipe supports. the engine and the standard modules are found in the
Weak supports may cause operational problems or section below. The nominal pressure of a connection
damages. may be higher than the nominal pressure required for
the pipe.
· All pipes must have provisions for drainage and
venting. Test pressures
· Pockets should be avoided, or, if they cannot be Typical test pressure according to the applicable EN
avoided, be equipped with drain plugs or air vents. standards is 1.43 times the design pressure The test
pressure to be used at actual operating conditions
· Drain pipes must be continuously sloping, and must always be checked with the respective stan-
vent pipes continuously rising.
dards.
· All pipe work must follow local rules and regula-
tions.
5.1.3 Pipe materials
For guidance, Table 18 lists the pipe material nor-
mally used in different systems in Wärtsilä designed
plants.

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Wärtsilä 50SG Power Plant Product Guide 5. PIPING SYSTEMS

System Max working Design Test pres- Max work- Design Nominal pressure
pressure (g) pressure (g) sure (g)3 ing temp. temp. EN

Fuel gas system before

8 bar 10 bar 15 Ambient 50°C PN16
compact gas ramp
Fuel gas system after
compact gas ramp 8 bar 10 bar 15 bar Ambient 50°C PN16

Starting air system 30 bar 33 bar 48 bar 75°C 75°C PN40

Instrument air system 7 bar 10 bar 15 bar Ambient 75°C PN16
Lube oil system 8 bar 10 bar 15 bar 95 °C 100°C PN16
Sludge and oily water
systems
6 bar 8 bar 12 bar 90 °C 90°C PN16

Cooling water system

5 bar 5.5 bar 8 bar 96°C 110°C PN16
(LT and HT)
Intake air system 0 1 bar No Ambient 75°C PN2,5
Exhaust gas system 0.07 bar 0.5 bar No 450°C 480°C PN2,5
Water supply system 5 bar 6 bar 10 bar Ambient 40°C PN16
Fire water system 9 bar 12 bar 18 bar Ambient 50°C PN16
Emission treatment
0.07 bar 0.5 bar No 450°C 480°C PN2,5
systems
Table 17. Pressures and temperatures which can be used as guidelines in the piping system design

3 Typical test pressure according to EN 13840-5 1

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Wärtsilä 50SG Power Plant Product Guide 5. PIPING SYSTEMS

System Flow media Size Piping material

Fuel gas system Natural gas or similar OD 6-28 mm E235+N
DN 15-300 P235 GH TC1
Lube oil system Lubricating oil OD 6-28 mm E235+N
DN 15-400 P235 TR1
Cooling water system Cooling water OD 6-28 mm E235+N
DN 15-400 P235 TR1
Water supply system Fresh water DN 15-200 AISI 304
Treated water OD 6-28 mm X2CrNi18-9
DN 10-200 X2CrNi18-9
Starting air system Compressed air OD 6-28 mm E235+N
DN 15-300 P235 GH TC1
Working air / instrument air system Compressed air OD 6-28 mm E235+N
DN 15-400 P235 TR1
Heat recovery system Steam OD 6-28mm E235+N, Cu
DN 15-300 P235 GH TC1, Cu
Fresh water DN 10-200 AISI 304
Treated water OD 6-28 mm X2CrNi18-9
DN 10-200 X2CrNi18-9
District heating system Fresh water DN 10-200 AISI 304
Exhaust gas system Exhaust gas DN 400-2200 Cor-Ten A
Charge air system Air DN 400-2200 S235 JR G2
Sludge system Lubricating oil, water OD 6-28 mm E235+N
DN 15-400 P235 TR1
Table 18. Standard pipe material used by Wärtsilä

Pipe diameters
5.1.4 Pipe dimensions
When sizing pipes, the required flow, the velocity,
and the length of the pipe must be considered. The
General higher the velocity in a pipe, the higher is the pres-
The pipes used in the Wärtsilä designed engines, sure drop per unit length.
standard modules and standard units follow applica-
ble parts of the EN standards. To ensure compatibil- Wall thickness
ity, the Wärtsilä engines, standard modules and units
are delivered with companion flanges, which can be When deciding the wall thickness, the pipe material,
welded to the mating pipes during installation. the type of media in the pipe, the pressure and tem-
perature of the transported media, and the outside
The nominal pipe diameter is given as DN (Diameter temperature must be considered.
Nominal). The nominal values do not generally coin-
cide with the actual pipe diameters in mm. See the
conversion table in appendix B.

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Wärtsilä 50SG Power Plant Product Guide 5. PIPING SYSTEMS

5.1.5 Flexible pipes and

pipe supports
Flexible pipe connections
To compensate for movements due to thermal ex-
pansion, and to prevent the engine vibrations from
being transferred to the pipe system, pipes must be
connected with the engine by means of flexible bel-
Figure 61. Pipe loop for enabling heat expansion
lows – rubber or steel bellows – or hoses.

5.1.6 Trace heating

To avoid freezing and ensure pumpability in cold
climates, the following pipes may need to be
equipped with trace heating:

Figure 59. Flexible bellow · Oily water pipes

· Urea solution pipes (if urea solution is used)
Bellows and hoses may also be required at other loca-
tions. · Lubricating oil pipes.
Most commonly, electrical heating is used, but also
Pipe supports steam, thermal oil or hot water can be used provided
The recommended distances between pipe supports that it is continuously available.
depend on the size of the pipe, and the weight of the The trace heating system is sized based on the esti-
substance, liquid or gas, transported in the pipe. mated heat losses in the pipes. To minimize heat
losses, trace heated pipes should be insulated. The
heating must be so arranged that it can be shut off.
Electrical trace heating cables can be of self-
regulating type or thermostat regulated.

Figure 60. Pipe supports

If the temperature of the pipes may vary, the support

must allow for thermal movement. If needed, heat
expansion must be enabled with bends, bellows,
flexible hoses, or loops. Figure 62. Trace heated and insulated pipe

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Wärtsilä 50SG Power Plant Product Guide 5. PIPING SYSTEMS

5.1.7 Insulation · The pipes from the compact gas ramps to the en-
gines
Generally, the following pipes should be insulated:
· Vent pipes, at least two pipes from each compact
· All trace heated pipes gas ramp, and one from each engine.
· All pipes included in heat recovery system Design notes
· The indoor portions of the exhaust gas pipes (and In fuel gas pipes, the amount of welded joints should
outdoors up to SCR if SCR used). be minimized. Bent pipes and tee connections should
In addition, the risks of fire and personnel injury due be used when possible. Flanged connections should
to hot surfaces must be considered. All pipes with a be avoided.
surface temperature over 60 °C should be insulated if
they are in the reach of the operating personnel. Fuel gas supply pipes

Suitable insulation material is mineral wool. To pro- The main fuel gas supply pipe should be sized for a
tect the insulation, it should be covered with alumin- gas velocity of about 20 m/s. The required pipe size
ium sheets. The sheets should be at least 1 mm thick. depends on the pressure and flow requirements.
The gas flow in the engine-specific supply pipes de-
pends on the engine output, the LHV (lower heating
5.1.8 Pipe instrumentation value) of the gas and the heat rate of the engine.
Thermometers should be installed wherever needed, Equation 1 shows how to calculate the pipe size in
for instance, before and after heat exchangers. By relation to gas flow and pressure under actual condi-
using thermo wells (metal housings), replacement of tions.
defect thermometers is possible without draining the
system. .
. P T
4× V act 4× V × b × Tact
b Pact
Pressure gauges can, for instance, be installed on the b
d= =
suction and/or discharge sides of pumps. vact ×π vact ×π
Local indication is sufficient if the instrument is ac- Equation 1. Formula for calculation of gas pipe size
cessible for reading and no central supervision is
needed.
d Diameter [m]
p Absolute pressure (not gauge) [bar (a)]

5.2 System specific notes T Temperature [K]

v Velocity of gas [m/s]

5.2.1 Fuel gas pipes V& Volumetric flow of gas [m3/h]

General act Actual conditions
The fuel gas system includes the following pipes: b base conditions

· The common gas supply pipe from the gas grid to

the gas manifold
· The engine specific gas lines from the gas mani-
fold to the compact gas ramps

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Wärtsilä 50SG Power Plant Product Guide 5. PIPING SYSTEMS

Gas vent pipes

5.2.3 Compressed air pipes
For safety reasons, and to prevent any back pressure
release, the gas vent pipes must be individually routed Compressed air pipes include:
out into open air. The pipes must be of the same size
as the vent pipe connections. The outlets must be · Starting air pipes
protected from becoming blocked. · Instrument air pipes
To prevent possible water condensate from entering
5.2.2 Lube oil pipes the engines or collecting onto pockets, the com-
pressed air pipes should have a continuous slope of
The piping must be built so that it can be dismantled min. 1/100 to manual or automatic drain outlets lo-
in suitable parts to make cleaning and pickling possi- cated at the lowest points. Swan necks (see Figure 64)
ble. Flanged connections and tee connections should must be used on all branches to the distribution
be used. All branches should be equipped with flange pipes.
connections.
To keep the pressure drop in the pipes within accept-
able limits, the following velocities are recommended:

Pipe dimension Suction Delivery

DN
m/s m/s
25 0.3-0.5 0.7-0.9
32 0.4-0.6 0.8-1.0
40 0.5-0.7 1.0-1.2
50 0.6-0.8 1.2-1.4
65 0.6-0.8 1.3-1.5
80 0.7-0.9 1.4-1.6
100 0.8-1.0 1.5-1.7
125 0.8-1.0 1.5-1.7
150 0.8-1.0 1.5-1.7 Figure 64. Compressed air pipes
200 0.8-1.0 1.5-1.7
250 0.9-1.0 1.5-1.7
300 1.0-1.1 1.5-1.7 If the instrument air system contains an air dryer, no
condensate will normally form in the piping system.
Table 19. Recommended velocities in lube oil
pipes However, for the event of the air dryer being out of
order, the same arrangements with sloping pipes and
swan necks should be employed in the instrument air
For determining pipe diameter, the following diagram system.
can be used:
If flexible hoses are used in the compressed air sys-
tem, there must be a closing valve in front of each
hose to allow shutting off the air flow.

Figure 63. Diagram for determining lube oil pipe

dimensions

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Wärtsilä 50SG Power Plant Product Guide 5. PIPING SYSTEMS

Pipe dimension HT and LT circuits Raw water

DN m/s m/s

5.2.4 Cooling water pipes 25 1.5-1.7

32 1.7-1.9
The following table shows recommended velocities, 40 1.9-2.1
and the figure shows the flow for different pipe sizes. 50 2.1-2.3
65 2.3-2.5
80 2.5-2.7
100 2.7-2.9 2.2-2.4
125 2.9-3.1 2.3-2.5
150 3.0-3.2 2.5-2.7
200 3.0-3.2 2.7-2.9
250 3.1-3.3 2.9-3.0
300 3.2-3.4 3.0-3.1
Table 20. Recommended velocities in cooling wa-
ter pipes

Figure 65. Water flow/velocity diagram

The cooling water vent pipes from the engine and the
expansion pipes from the engine auxiliary module
must be run separately to the expansion vessel(s) and
be continuously rising with a slope of min. 1/100.
Welded connections should be used, but flanged
connections can also be used if the installation, main-
tenance, cleaning or pipe material so demand.

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Wärtsilä 50SG Power Plant Product Guide 5. PIPING SYSTEMS

Maximum back pressure

The entire exhaust gas line must be designed as short
5.2.5 Intake air ducts and straight as possible to minimize flow restrictions.
The limit of the total pressure drop for the exhaust
Each engine must have its own intake air ducting. gas system, the maximum back pressure, is 5000 Pa.
The maximum permissible total pressure drop in the
The permissible pressure drop in the entire intake air intake air and the exhaust gas systems together is
system, including the intake air filter and the silencers, 7000 Pa.
is max 2000 Pa. The maximum permissible total pres-
sure drop in the intake air and the exhaust gas sys- Bellows and pipe supports
tems together is 5000 Pa.
Besides the engine being connected to the branch
Design velocities: 20-30 m/s. pipes with flexible bellows, bellows may also be
needed before and after the silencer.
The intake air ducts should be as short and straight as
possible. Any bends shall be made with the largest The pipes have to be properly supported with fixed
possible bending ratio R/D, or at least 1.5. supports and sliding supports that allow the duct to
move in axial direction. The exhaust gas module in-
cludes one fixed and one sliding support. Other sup-
port locations must be determined case by case.

Figure 66. Bending ratio

Flanged connections should be used.

When using the exhaust gas module, the steel support
for the intake air ducts is the same as for the exhaust
gas system. The intake air ducts in the exhaust gas
module are connected to the turbochargers with
flexible connection pieces.
Figure 67. Examples of fixed and sliding supports
for exhaust gas ducts

5.2.6 Exhaust gas ducts

Insulation
General The indoor exhaust pipes must be insulated all the
To prevent exhaust gases from entering an engine way from the turbocharger, and the insulation must
that is out of service, each engine must have its own be protected by metal cladding or similar. At the part
exhaust gas duct system all the way from the engine closest to the turbocharger, the insulation and clad-
into open air via the stack. In the exhaust gas module, ding should be made as a removable piece to facilitate
the branch pipes from the two turbochargers of the maintenance.
engine are joined to a common exhaust gas pipe.
There must be no risk for the insulation material
Any bends shall be made with the largest possible being drawn into the turbocharger during opera-
bending ratio R/D, or at least 1.5. tion.
The design velocity in the common pipe is 20 – 30
m/s.

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Wärtsilä 50SG Power Plant Product Guide 5. PIPING SYSTEMS

If the plant contains SCR, also the outdoor pipes up 5.2.8 Steam pipes
to the SCR should be insulated.
Steam in contact with the cooler pipes will condense.
Water drainage On start-up of the system, when steam comes in con-
tact with the cold pipe work, the condensing rate will
To prevent water from entering the engine, the ex- be at its maximum – the “starting load”. When the
haust gas pipes shall be provided with water drains at pipe work has warmed up, some condensation will
the lowest points. Normally, the system is drained still occur due to the heat transfer to the surrounding
from the silencers. air – the “running load”.

Exhaust gas stack The resulting condensate falls to the bottom of the
pipe and is carried along by the steam flow. The lines
Each engine must have its own exhaust gas stack, but must be properly drained to avoid condensate build-
in installations with two or more engines, several ex- up and consequent risks of water hammering and
haust gas ducts may be conducted to a common high pressure drops due to restricted free area for the
multi-pass chimney or cluster chimney, which gener- steam.
ally gives better lift of the emissions.
The draining should be arranged at regular intervals,
The stack should be sized for a velocity of about 20 - distance being subject to line size and frequency of
30 m/s at the end. Higher exhaust gas velocity may cold start conditions. A distance of 30-50 m can be
cause noise emissions. used as a guidance value. Lines should also be
drained at all low points where condensate will col-
Due to gas velocities created by a possible gas defla- lect. For the same reason, proper supporting is essen-
gration, under-pressure (partial vacuum) may occur. tial, as a sagging pipe will form a low point.
Therefore, the stack must be sized to sustain an un-
der pressure of 0.3 bar without collapse. To ensure proper draining, pockets of adequate size –
usually same size as the mains – must be used.
In case the inner surface temperature of the stack is
below 50°C, there is a risk for condensation in the
pipes. Insulation may therefore be needed in plants
where heat is recovered from the exhaust gases.

5.2.7 Miscellaneous
Crankcase vent pipes
The crankcase vent pipe from the engine is con-
ducted to the oil mist separator. The pipe must be Figure 68. Drain pocket
connected to the engine with a flexible connection.
The crankcase gases from the oil mist separator must Eccentric reducers should be used to avoid pockets.
be led out to open air. The outlet should be equipped
with a condensate trap (oil trap) so arranged that any
residual oil flows back to the oil mist separator.

Figure 69. Eccentric reducer

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Wärtsilä 50SG Power Plant Product Guide 5. PIPING SYSTEMS

For the same reason, strainers must be installed hori- Even these velocities can be high in terms of their
zontally. This will at the same time maximise the ef- effect on pressure drop. In longer supply lines, it is
fective screening area. often necessary to restrict velocities to 15 m/s to
avoid high pressure drops. Long pipelines should
always be checked for pressure drop.
5.2.9 Sizing of steam pipes Table 21 indicates pipe line capacities for different
As a general rule, a velocity of 25 to 30 m/s is used pipe sizes and velocities at 7 bar(g).
for saturated steam. A velocity of 30 m/s should be
considered a maximum, as above this, noise and ero-
sion may occur particularly if the steam is wet.

Pipe size (nominal)

Velocity
[m/s] DN15 DN20 DN25 DN32 DN40 DN50 DN65 DN80 DN100 DN125 DN150
15 44 77 125 217 296 487 695 1073 1848 2904 4194
25 74 129 209 362 493 812 1158 1788 3080 4841 6989
40 118 206 334 579 788 1299 1853 2861 4928 7745 11183
Table 21. Steam pipe flow capacities [kg/h] for specific velocities at 7 bar(g)

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Wärtsilä 50SG Power Plant Product Guide 6. ELECTRICAL SYSTEM

6. ELECTRICAL SYSTEM

· High voltage switchyard comprising necessary

6.1 General feeders for transformers and lines
· A station transformer (step-down transformer) for
the internal power consumption
6.1.1 System overview
· Low voltage power distribution system compris-
Below is an overview of the electrical system in a
ing the main low voltage switchgear(LV), motor
typical Wärtsilä 50SG power plant.
control centres (MCC), distribution boards and
The main parts in the system are: panels (in this guide all called LV switchgear)
· DC power supply system
· Engine driven medium voltage generators
· Lighting and small power system
· Medium voltage switchgear for connecting the
generators and the outgoing feeders · Grounding system
· Step-up transformers for raising the generated · Cables
voltage to the correct high voltage level.

Figure 70. Typical electrical system overview

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Wärtsilä 50SG Power Plant Product Guide 6. ELECTRICAL SYSTEM

Each engine generator set delivers power through a It may be built up as shown in Figure 71. The me-
circuit breaker in the medium voltage switchgear, dium voltage generators are connected to medium
which distributes the generated power to a national voltage switchgear. In a big plant with many genera-
grid, a local grid, and/or directly to local consumers tors it may be necessary to divide the generators in
(factory or utility), possibly via a step-up transformer. several groups and connect each group to electrically
isolated bus bars in the switchgear. The system set up
The station transformer lowers the generated me- is dependent on the specific circumstances at the
dium voltage power to the voltage level used in the plant and is a design issue to be agreed between seller
power plant. The low voltage switchgear distributes and plant owner, taking into account the load flow,
electricity to the plant power consumers. There may full load current and level of fault current. The power
be separate MCC (motor control centre) cabinets or is evacuated trough one or several feeders either on
the motor control may be included in the plant LV the same voltage level or the voltage is raised to a
switchgear and in local control cabinets. higher level by means of one or several transformers.
The main low voltage 400V switchgear is fed trough
one or several station service transformers. The
switchgears may be divided in several bus bars de-
pending on size and logical structure of the system.
The latest electrical IEC standards are followed.
Selection of main components and sizing of different
current currying part like bus bars and cables are
based on ambient conditions and system calculations.

6.1.3 Protection relays

The protection relays used are selected to give a full
coverage and include all necessary features in the me-
dium voltage distribution protection systems. Addi-
tionally the relays may include a number of other in-
novative and unique features, such as comprehensive
and versatile setting and programming possibilities,
programmable blocking and output matrix, distur-
bance recorder, evaluation software and continuous
self-supervision.
Several communication protocols are available in the
relays. Maximum demand measurement quantities
and disturbance recorder are available for load profil-
ing and fault evaluation.
Figure 71. Principle diagram of a medium voltage
power plant Thanks to optional integrated transducers, any meas-
ured and calculated values can freely be connected to
the mA outputs.
6.1.2 Basic system design
The design of the electrical system depends on size of
the system, the number of connected generators and
number of transformers.

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Wärtsilä 50SG Power Plant Product Guide 6. ELECTRICAL SYSTEM

The micro processor based generator protection relay Hazardous area classification
includes all the essential functions needed for protec-
tion of small or medium-sized power generators in The electrical equipment in a hazardous area must be
modern fully automatic power plants. Further the designed for the classification of the area.
relay includes several programmable protection func-
tions, trip circuit supervision, circuit breaker protec- Minimum seismic design
tion and communication protocols for various pro-
tection and communication situations. The equipment is designed in order to resist the ef-
fects of seismic ground motions acc. to UBC 97

6.1.4 Protection classes of

6.1.5 Internal power con-
electrical equipment
sumption
Enclosure protection class The following table lists the main power consumers
The electrical equipment used in dry, indoor condi- along with rough estimations of the power consump-
tions should be of class IP20 or IP2X according to tion in a plant with seven W18V50SG engines. The
the Ingress protection codes defined in the IEC 529 values used in the table are maximum values based on
standard. The minimum requirement for equipment the nominal power of the motors. In practice, how-
installed outdoors is IP23, but normally equipment ever, the motors will never be running at 100% si-
intended for outdoor installations should be of class multaneously.
IP34 or IP54.
Note! The power consumption depends
Table 22 shows typical applications for various IP largely on the plant configuration and the ambi-
codes ent conditions. The values in the table must not
be used as design data.
IEC Name Typical application
classification
IP20 Ordinary Indoors, dry ambient
IP22 Drip proof Humid ambient
IP23 Spray proof Outdoors
IP34 Splash proof Wet or humid ambient
IP54 Dust proof Dusty ambient
IP55 Jet proof Wet ambient
IP67 Water tight Dusty ambient
IP68 - Under water
Table 22. Typical ingress protection applications

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Wärtsilä 50SG Power Plant Product Guide 6. ELECTRICAL SYSTEM

Consumer Power Type of use

Engine-specific consumers
Engine auxiliary module 7 x 109 kW Stand-by engine
(mainly pre-heating and pre-lubrication)
Radiator fans 7 x 180 kW Continuous
Ventilation 7 x 90 kW Continuous
Common auxiliary systems
Starting air compressor 50 kW Intermittent
Instrument air compressor 20 kW Intermittent
Maintenance water pump 2 kW Intermittent
Lubricating oil transfer pump 2 kW Intermittent
Trace heating, heating of tanks 30 kW Seasonal
Common electrical systems
Heaters, battery chargers, etc. 20 kW Intermittent
Common civil systems
Ventilation (switchgear rooms, control room, 100 kW Continuous
workshop, etc)
Lighting 50 kW Continuous
Miscellaneous (cranes, workshop, etc.) 150 kW Intermittent
Table 23. Main power consumers and installed power in a plant with seven W18V50SG engines

6.2.2 Neutral grounding

6.2 Generator system The star point of the generator is used for grounding
of the MV system. Each generator star point is con-
nected to a grounding resistor in the neutral ground-
6.2.1 Measurement and pro- ing cubicle, one per generator, . The system is nor-
tection mally high resistance grounded. The neutral ground-
ing cubicles delivered by Wärtsilä are equipped with
The generator is equipped with measuring transform- current measuring transformers for earth fault pro-
ers for both voltage and current. The transformers tection and differential earth fault protection. Earth
are used for both generator protection and measuring fault current is typically limited to 5A
of electrical data. Two types of protection relays are
used; a differential protection relay and a multifunc- In a plant with many generators it may be advisable
tion generator protection relay. These two relays and to use an earthing transformer serving several genera-
a monitoring unit are normally located in the genera- tors thus limiting the number of grounding resistors.
tor set control cabinet.

Figure 72 Generator with zigzag earthing trans-

formers

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Wärtsilä 50SG Power Plant Product Guide 6. ELECTRICAL SYSTEM

The medium voltage main circuit and equipment in a

6.3 Medium voltage switch- cubicle is supported by a secondary circuit housed in
gear a low voltage compartment. The secondary apparatus
comprise control equipment, meters, switches, actua-
tors, protection equipment, and terminal blocks for
remote connections.
6.3.1 General
Generally, the medium voltage switchgear comprises
The medium voltage switchgear consists of a number the following cubicles:
of cubicles installed side by side with a common main
bus bar running horizontally through the switchgear. · Incoming feeders from the generators (one per
generator set)
· Outgoing feeders to power transmission systems
(possibly via a step-up transformer) or local con-
sumers
· Outgoing feeder to the low voltage station service
system (station transformer)
· Possibly a bus bar measurement transformer. (Bus
bar measurement may also be included in a station
transformer feeder cubicle.)
· Possibly one or more bus tie cubicles if the bus
Figure 73. Medium voltage switchgear bar is composed of two or more sections.

The main bus bar runs through the main bus bar
compartments of the cubicles. 6.3.2 General design princi-
ples
Basic requirements
The medium voltage switchgear and all components
are designed, manufactured, assembled and tested in
accordance with the latest applicable IEC standards.
The switchgear is of metal enclosed, compartmented
type.
The required current and voltage withstand capability
ratings of the bus bars, interrupting ratings of the
circuit breakers and other equipment shall be based
on the system studies.
All cubicles must be equipped with earthing switches.

Circuit breakers
The circuit breakers are of three pole truck or cas-
Figure 74. Cross section of a medium voltage sette withdrawable type to support interchange and
switchgear cubicle (example) maintenance of the breakers. For economical and
practical reasons, circuit breakers of equal rating
should be interchangeable.

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Wärtsilä 50SG Power Plant Product Guide 6. ELECTRICAL SYSTEM

Enclosure The generator circuit breakers are spring operated,

and the spring is automatically charged when neces-
The medium voltage switchgear is designed to be sary by means of an electric motor. Normally there is
located indoors in a dry, dust free and tempered a handle for manual charging the spring as well.
room. In general it is metal-enclosed and air-
insulated. Typically cables are connected from the Other main circuit apparatus
bottom.
The generator feeder cubicles contain current and
Power supply voltage measuring transformers for the protection
functions and the power monitoring unit. Besides for
Generally, 110/125 VDC is required for breaker con- protection, the voltage measurements are also used
trol, protection relays, etc. Low voltage power needed for synchronization.
for lighting and heating (230/110 VAC) can be taken
from the low voltage power system. Secondary apparatus
Heating and cooling The breakers are equipped with coils for breaker re-
mote open and close control. Generator breakers are
To prevent condensation, anti-condensation heaters also provided with an under voltage coil which will
controlled by thermostats are installed to ensure that trip the breaker if the control voltage is lost. At a
the inner parts of the cubicles are kept above the am- breaker trip, an alarm signal is to be sent to the plant
bient temperature. control system.
The switchgears should be placed in a dry and dust Auxiliary contacts are used for remote breaker posi-
free room with air conditioning. Forced air cooling tion indication. Interlocks need to be built to prevent
within the switchgear is normally not needed mal operation of the breaker
The generator circuit breaker protection relay, differ-
6.3.3 Medium voltage bus ential protection relay, and power monitoring unit are
included in the generator set control cabinet.
bars
The main bus bars are located in a separate com-
partment isolated from the other compartments by 6.3.5 Main outgoing feeder
metal walls. The compartment contains copper or cubicles
aluminium bus bars, which are supported by cast
resin insulators to withstand dynamic forces caused The grid feeder circuit breaker is of the same type as
by short circuit currents. Bus bars are rated for nomi- the generator breakers. Loss of control voltage
nal- and short circuit currents. should generate an alarm signal. SF6 type breakers are
recommended.
The grid feeder cubicle is to be equipped with current
6.3.4 Incoming feeder cubi- and voltage measuring transformers, Minimum pro-
cles tection requirements for the grid feeder circuit are:

Generator circuit breaker Protection Symbol ANSI No.

Over current (I >)(I>>) 50
Wärtsilä recommends using SF6 circuit breakers (cir- Earth fault (Io >) 50N
cuit breakers isolated with SF6 gas). If vacuum circuit
breakers are used, the generators should be equipped Table 24. Minimum protection requirements for
the grid feeder circuit
with surge arresters and surge capacitors.

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Wärtsilä 50SG Power Plant Product Guide 6. ELECTRICAL SYSTEM

6.3.6 Station transformer 6.4 High voltage substa-

feeder cubicles
tions
The station transformer feeder circuit breaker is of
the same type as the grid feeder circuit breaker, and
has the same protection. 6.4.1 General
The HV Substations for a Power Plant normally con-
6.3.7 Bus bar voltage meas- sists of transformer- and line feeder bays with a
common bus bar system and associated equipment
urement for protection, measuring etc. The bus bar configura-
The main bus bar is equipped with voltage trans- tion is according to the specific needs at the power
formers for synchronization of the generators and for plant. Normally a single- or alternatively a double bus
system voltage- and frequency protection relays. bar system is used. The main components are in-
stalled on steel structures which then are mounted on
Minimum protection requirements are: concrete foundations. The complete substation is
located within a fenced area.
Protection Symbol ANSI No.
Over/under frequency f>, f< 81H, 81L
(typically alarm only)
Over/under voltage U>, U< 27, 59
(typically alarm only)
Residual voltage (earth U0 > 59N
fault)
Table 25. Minimum protection for bus bar voltage
measurement transformers

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Wärtsilä 50SG Power Plant Product Guide 6. ELECTRICAL SYSTEM

Figure 75. High voltage substation

· Measuring Bay
6.4.2 General design re- · Bus bar System
quirements · SCADA System
· Energy tariff metering
The substation is designed and constructed according
to relevant IEC standards for electrical components · DC System
and DIN standard for mechanical components, · Communication system
nominal voltage levels are 72,5 kV, 145 kV and
245kV (higher voltages up to 500 kV may be used for Transformer bay
bigger power plants) Normally the substation is de-
signed for a short circuit level of 31,5 kA/1sec and Generally the transformer bay consists of following
creep age distance of 25 mm/kV, however the design main components
of the substation shall always be based on profession-
· SF6 Circuit Breaker
ally made studies in order to determine the actual
technical needs. · Rotary type disconnector
· Post Insulators
Generally a substation consists of following main · Al conductor and bus bar tubes
parts: · Steel structures
· Control and Protection Panel (normally lo-
· Transformer Bay
cated in substation building)
· Line Feeder Bay · Step up transformer with integrated CTs for
· Bus coupler Bay protection and measuring, lightning arresters

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Wärtsilä 50SG Power Plant Product Guide 6. ELECTRICAL SYSTEM

Line feeder bay 6.5 Transformers

Generally the Line Feeder bay consists of following
main components
6.5.1 General
· Lighting arresters
· Capacity voltage transformers A transformer consists of a three-legged magnetic
· SF6 Circuit Breaker core in a transformer tank with primary and secon-
dary windings around the core, bushings, and a tap
· Rotary type disconnector
changer. The function of the transformer is to supply
· Rotary type disconnector with earthing the load to another voltage level.
switch
· Post Insulators The primary- and secondary windings have no gal-
· Al conductor and bus bar tubes vanic connection and thus form two different electri-
· Current transformers cal systems.
· Steel structures and Gantry Towers
· Control and Protection Panel (normally lo-
cated in substation building) 6.5.2 Power (step-up) trans-
former
Bus coupler feeder
The step-up transformer(s) is to be sized for the rated
Generally the transformer bay consists of following power of the generators connected to the trans-
main components former.

· SF6 Circuit Breaker The power transformers used by Wärtsilä are oil im-
· Current transformers mersed, conservator transformers with Oil Natural
· Rotary type disconnectors Air Forced (ONAF) cooling.
· Post Insulators The transformer is equipped with the following main
· Al conductor and bus bar tubes equipment
· Steel structures
· Control and Protection Panel (normally lo- · Surge arresters t
cated in substation building) · Gas relay
· Winding temp monitoring
Bus bar system · Oil level monitoring
· Tap changer.
The bus bar system consists of Al tubes installed on
support insulators and steel structures. The system is
designed in order to meet nominal- and short circuit
currents and withstand mechanical stresses and dy- 6.5.3 Station transformer
namic forces caused by short circuit currents, ade- The station service transformer (auxiliary trans-
quate clearances for all live parts within substation former) one or several, is sized for the for the plant
area is according to applicable Standards auxiliary loads with a certain margin.
The main design alternatives for station transformers
are:

· dry type transformers (cast resin transformers)

· oil immersed transformers, either hermetically
sealed or conservator type

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Wärtsilä 50SG Power Plant Product Guide 6. ELECTRICAL SYSTEM

The transformers delivered by Wärtsilä are either dry

type transformers, or oil insulated hermetically sealed 6.6 Low voltage switchgear
transformers with mineral oil as insulation and cool-
ing medium.
6.6.1 Overview
The low voltage power distribution system in the
plant provides the power supply to the engine auxil-
iary equipment, such as pumps, fans, heaters and
compressors, the ventilation system and the building
electricity system. The system includes:

· A main low voltage switchgear (main distribution

switchboard), which distributes power to possible
motor control centres, control panels, and sub-
distribution boards.

Figure 76. Station transformer oil type (example) · Possibly one or more motor control centres
(MCCs), which supply motors
Dry type transformers are placed indoors, preferably · Radiator switchgear
close to the plant LV switchgear. The oil insulated,
hermetically sealed transformers can be placed out- · Control panels and sub-distribution boards, which
doors. supply motors and other electrical consumers in
the plant.

Figure 77. Station transformer dry type (example)

The transformers are cooled by natural circulation. Figure 78. Low voltage switchgear (example)
When located in a switchgear room, or in a separate
area, it is important to provide the transformer with Generally a low voltage switchgear, motor control
sufficient cooling air. centre, sub-distribution board or panel contains the
following equipment and apparatus:

· A common bus bar

· One or more incoming feeders. The main LV
switchgear is fed from the MV switchgear via the
station transformer, possibly also from an emer-
gency generator or other alternative feed lines.
Other switchgears are fed from the main LV
switchgear.

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Wärtsilä 50SG Power Plant Product Guide 6. ELECTRICAL SYSTEM

· Outgoing feeders to motor control centres, con- Standards

trol panels, sub-distribution switchboards, motors
and other consumers The LV switchgear, switchboards, and motor control
centres shall be designed, manufactured, assembled
· Possibly a bus bar voltage metering transformer and tested in accordance with the latest applicable
IEC standards.
· Secondary equipment for measurements and pro-
tection.
All motor control centres and auxiliary control panels 6.6.3 Bus bars and conduc-
are supplied by three phase low voltage. tors
Each switchgear, switchboard and MCC contains a
6.6.2 Design principles common bus bar or terminal. The ratings of the bus
bar are selected to match the connected load.
Enclosure The switchgear is provided with separate bus bars for
neutral and protective earth.
The switchgears are designed for indoor use, except
the radiator switchgear which is designed for outdoor
use.
6.6.4 Incoming feeders
The low voltage standard switchgears delivered by
Wärtsilä are metal enclosed with natural ventilation. General
The compartmentalization is usually FORM4A (metal
clad), and the assembly is type tested according to Typically, there is one incoming feeder per switchgear
EN60439-1. or switchboard. The feeders shall be sized for the
maximum power load. The main low voltage feeder,
Power supply which is supplied from the station transformer, must
be rated to match the rating of the station trans-
Generally, 110 VDC is required for breaker control former.
motors, protection relays, etc. Power needed for
lighting and heating can be taken from the low volt- Circuit breakers
age power system.
The feeder circuit breakers are fixed mounted
Secondary wiring moulded case circuit breakers or air circuit breakers.

The switchgear includes necessary numbers of termi- Measurements and protection

nal blocks for signal wiring to the plant control sys-
tem. Voltage measurement is required if synchronization
will be needed. Possible synchronization is handled
Heating and cooling by the plant control system.

To prevent condensation, anti-condensation heaters Circuit breaker protection is generally incorporated in

controlled by thermostats are installed to keep the the breaker.
inner parts of the cubicles above the ambient tem-
perature.
6.6.5 Outgoing feeders
If the switchgear is placed in rooms with air condi-
tioning, forced air cooling is normally not needed. Feeder types
The most common feeder types are direct feeders,
heater feeders and motor starters.

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Wärtsilä 50SG Power Plant Product Guide 6. ELECTRICAL SYSTEM

Direct feeders 6.6.7 Emergency generator

Feeders to control cabinets and lighting are direct An emergency generator (black start unit) is used to
feeders equipped with switch fuses, or alternatively, supply power in case of a black-out situation. The
MCCB:s or MCB:s. generator should be sized to supply at least the power
needed for starting one main engine generator set.
Motor starters See the table below. The required power is much
higher if the emergency generator is to also supply
Motor starters are typically of direct on-line type. A the ventilation systems and emergency lighting.
motor starter contains at least:
Consumer Power
· A contactor that switches the power on and off Engine specific auxiliary systems
· A circuit breaker, either a miniature circuit breaker Pre-lubrication pump 30 kW
(MCB) or moulded case circuit breaker (MCCB) Preheating unit(s) 109 kW
for breaking the circuit at over-current
Common auxiliary systems
· A thermal overload relay Starting air compressor 56 kW
Instrument air compressor 20 kW
· A control switch
Common electrical systems)
· Running and fault signal lamps Battery charging ~6 kW

· Terminal blocks for remote supervision and con- Table 27. Estimated power requirements for start-
trol. ing one engine generator set

Each motor starter is equipped with auxiliary contacts

to indicate the contactor closed/open status, and 6.6.8 Emergency bus bar
contacts to indicate the tripped status.
The main LV switchgear can be equipped with an
Other feeder types emergency bus bar fed from an emergency generator
(black start unit). Besides for the emergency start-up
Heater feeders have protection and control. of engine generator sets, the emergency bus bar may
feed highly critical consumers, such as emergency
Protection lighting. The emergency bus bar is connected to the
LV bus bar with a bus tie breaker.
Outgoing feeders shall be equipped with protection
suitable for the load. The basic protections which
must be included for outgoing feeders are:

Protection Symbol ANSI No.

Over current (I >) 50
Short-circuit (I >>) 51
Table 26 Basic protection for outgoing feeders

6.6.6 Bus bar voltage meas- Figure 79. Emergency bus bar and black start gen-
urement erator set (BS)

Bus bar voltage measurement is needed if two bus

bars or a bus bar and an incoming feeder will be syn-
chronized. This is the case, for instance, if there is a
black-start unit.

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Wärtsilä 50SG Power Plant Product Guide 6. ELECTRICAL SYSTEM

6.7 DC system 6.7.2 DC system design

General
6.7.1 DC power consumers A DC system consists of batteries, battery charger(s)
(rectifiers), and a DC distribution system. The system
DC (direct current) power is used by the control and
can be built as one compact DC unit.
automation systems, the protection relays, and the
switchgears. Using DC power for the control system
and generator breaker control ensures that vital func-
tions will work in case of failure in the auxiliary AC
voltage supply. Two voltage levels are used:

· 24 VDC is used by the engine control system

(24/120+40+ 400Ah/4 EG-sets), the plant con-
trol system, and the compact gas ramps
· 110VDC is used by the engine valve drive system
(110/30+15 90Ah/ 4 EG-sets)
· 110 VDC is used in the switchgears for control-
ling circuit breakers (nominal current: 2x15 A +
1x15 A stand-by) and for the instrumentation.
Figure 80. An example of a DC unit
The 24/110 VDC consumption can be estimated as
follows:
Normally, the rectifiers supply the load. The battery
bank supplies the load for a limited time if the mains
Consumer Estimated
consumption supply is interrupted.
Common control panel 300 W
Batteries
Generator set control panels 100 – 200 W / panel
EAM control panels 100 W / panel Lead acid batteries are the preferred battery type.
Engine control system 2 x 275 W /engine (110 VDC) Nickel-cadmium batteries can also be used.
(main and backup supply) 2 x 200 W /engine (24 VDC)
The required operating time with batteries is normally
Compact gas ramps 100 W / unit 5 - 10 hours.
Fire detection system 100 W
Table 28. Estimated 24/110 VDC consumption Battery chargers (rectifiers)
The charger capacity is selected so that the charger is
For switchgears, the DC power consumption de- capable of feeding the total plant load while simulta-
pends on how frequently the circuit breakers are op- neously charging the batteries. The charger is also
erated. Generally, the consumption under normal capable of supplying load if the battery is discon-
operating conditions can be estimated to 20 VA per nected.
cubicle, plus the power consumed by protection re-
lays, transducers, etc. The DC system is normally provided with redundant
chargers

DC distribution system
The DC-distribution system consists of miniature
circuit breakers (MCB:s) for the batteries, battery
chargers and outgoing feeders.

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Wärtsilä 50SG Power Plant Product Guide 6. ELECTRICAL SYSTEM

6.8 Grounding

6.8.1 General
The general purpose of the grounding system is to
protect life and property in the event of short-
circuits, earth faults, or transient occurrences (for
instance, caused by lightning or switching opera-
tions). The protection is arranged by preventing a
dangerous potential difference between the reference
earth and the accessible conductive (metallic) equip-
ment and structures.
There are the following three types of grounding
connections in a plant:
Figure 81. Grounding types (TN-S system)
· Neutral point grounding for establishing a com-
mon ground reference within a connected grid
The main components of the grounding system are:
· Safety grounding of system parts that are normally
not energized but may become energized under · The grounding grid
abnormal or fault situations · The main grounding bar
· Equipment grounding for ensuring a low imped- · Grounding cables
ance path for the ground current, and a fast trip of
the faulty circuit in case of an earth fault. · Lightning protection electrodes

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Wärtsilä 50SG Power Plant Product Guide 6. ELECTRICAL SYSTEM

Figure 82. A simplified grounding diagram for a power plant (example)

6.8.2 Grounding grid

The grounding grid is a copper grid installed under
the foundation of the engine hall and possibly the
surrounding site area. The design of the grounding
and the required area of the grid depend on the soil
qualities, maximum earth fault current and time, the
network configuration, and the number of incoming
lines and grounding wires.
The impedance of the grounding grid must be such
that it ensures safe step and touch voltages. The most
suitable impedance value depends on the soil proper-
ties.

Figure 83. An example of a grounding grid

The recommendation is to ground at sufficient depth

to ensure moisture during dry seasons and to avoid
freezing in winter. If needed, vertical grounding elec-
trodes can be installed under the grid to improve the
earth contact.

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Wärtsilä 50SG Power Plant Product Guide 6. ELECTRICAL SYSTEM

Inadequate soil around the power plant may make it 6.8.5 Lightning protection
necessary to install the grounding grid at a distance
from the plant. For lightning protection, lightning rods with lightning
down conductors of copper from the rods down into
the earth must be installed in all high structures.
6.8.3 Main grounding bar The underground lightning conductors should be
The main grounding bar is a copper bar which is di- connected to the plant grounding system in order to
rectly connected to the grounding grid. All major prevent the build up of potential differences, which
equipment, and possible other grounding bars, should could damage sensitive components, or cause per-
be connected to the main grounding bar. sonal injury or loss of life.

The main grounding bar must be sized according to

national standards.
6.9 Cabling
6.8.4 Neutral point grounding
The main alternatives for neutral point grounding are 6.9.1 General
illustrated below. The type of grounding to be used
depends on the grid, the power feed, possible trans- The plant comprises medium voltage cables, low
formers, etc. voltage cables, DC cables and grounding conductors.
The required amount of cables depends on the extent
of the plant and the plant layout. The required cable
size (diameter) for a connection depends on the volt-
age, current, temperature, mounting method, number
of cables within the same conduit, type of cable, type
of fed equipment, and cable length.
Power cables must fulfil the following basic require-
ments:

· The cable dimension must be selected so that ca-

Figure 84. Neutral grounding, main alternatives ble losses are acceptable.
· The cable insulation level must withstand existing
The generator neutral point is typically high resistance system voltages.
grounded. Other types are used when required.
· The cable must withstand existing short-circuit
Station service systems equipped with neutral con- currents in the system.
ductor are always solidly grounded. The recom-
mended grounding method is TN-S (separate neutral · The voltage drop in the cable must not exceed
and protective earthing conductors). 110 VDC sys- acceptable limits. For maximum allowed voltage
tems are floating provided with earth fault monitor- drops in cables for various applications and loads,
ing, 24VDC systems directly grounded. refer to applicable standards.
Neutral grounding systems shall ensure the efficient · The cable temperature in all operating conditions
protection of equipment and personnel. must remain under acceptable limits.
· The cable must fulfil requirements regarding fire
withstand capability.

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· The cables must withstand existing mechanical 6.9.3 Low voltage cables
loads and vibrations.
3-phase low voltage cables are installed from the
Cabling routes and cable qualities must be selected in main low voltage switchgear to all motor control cen-
such a way that they do not cause disturbances to tres, switchgears and control panels containing motor
other systems. controls, and to the building switchboard.
To determine the technically and commercially most 1-phase low voltage cables are installed from the
suitable cables for each case, Wärtsilä performs a ca- main low voltage switchgear to the one phase con-
ble optimization study. The calculations are based on sumers.
standards such as IEC guidelines. See App A Stan-
dards and codes on page 158
6.9.4 DC cables
6.9.2 Medium voltage cables DC cables are installed from the DC cabinet(s) to the
medium voltage switchgear, to the main low voltage
Single core medium voltage cables are installed from switchgear, to the UNIC main units on the engines,
each generator set to the respective generator breaker and to the control cabinets in the control room.
cubicle in the medium voltage switchgear, from the
medium voltage switchgear to the station trans-
former, and from the medium voltage switchgear to 6.9.5 Grounding conductors
the step-up transformer in the switchyard. Neutral
point ground cables are pulled from each generator to Grounding conductors are installed between the
the neutral grounding cubicle or possible grounding grounding bar and the grounded equipments, for in-
transformer. stance, switchgears, control panels, engine generator
sets, and auxiliary units.
The material and cross-section area of the grounding
conductors depend on the earth resistance and power
system arrangements and must be decided from case
to case.

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Wärtsilä 50SG Power Plant Product Guide 7. PLANT CONTROL SYSTEM

7. PLANT CONTROL SYSTEM

7.1 Overview

Figure 85 shows a simplified picture of the system architecture of a standard plant control system. The generator
set control cabinets, the common control cabinet and the workstations are typically located in a control room.

Figure 85. Plant control system architecture (simplified)

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Wärtsilä 50SG Power Plant Product Guide 7. PLANT CONTROL SYSTEM

Each engine generator set has a generator set con- The control system is always delivered by Wärtsilä,
trol cabinet. It handles the following functions: but the customer can use existing user interfaces as a
complement to the Wärtsilä workstations. Third party
· Engine start and stop connections are supported over Ethernet OPC
through a firewall.
· Engine speed and load control via UNIC
· Generator set voltage and reactive power control
through the automatic voltage regulator
· Supervision and control of engine auxiliary
7.2 Generator set control
equipment via the EAM module cabinet
· Alarm activation and indication
· Safety functions, such as start blocks, shutdowns, 7.2.1 Overview
control of gas shut-off and vent valves in the
compact gas ramps, and control of possible en- Figure 86 shows the front of the standard generator
gine-specific main shut-off valves set control cabinet. The cabinet is typically located in
the control room.
· Control of engine-specific ventilation units and
roof monitors if they are remotely controlled.
The common control cabinet, generally one per
plant, has the following main functions:

· Synchronization and control of outgoing feeder

breakers
· Monitoring of common auxiliaries (lube oil tanks
and pumps, compressed air systems, etc.)
· Control of a common main gas shut-off valve (if
installed)
· Power management functions, such as load shar-
ing, load shedding, automatic start/stop, and load
following (options)
· Monitoring of the transformers, the plant LV
switchgear, and the DC system
· Control of a possible black start unit
· Gas supply measuring (option) Figure 86. Generator set control cabinet
· Supervision of fire and gas detection systems
· Supervision of environmental parameters.
At the WOIS and WISE workstations, the operator
can start and stop the engine generator sets, change
set values, and supervise the plant through process
displays, alarm and event lists, graphical trends and
reports.

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Wärtsilä 50SG Power Plant Product Guide 7. PLANT CONTROL SYSTEM

The front panel contains frequency, current, voltage,

power factor and active power meters, an emergency
stop button, and a manual control unit with start and
stop buttons and control switches. It also contains
the front panels of the power monitoring unit, the
generator protection relay, and the differential protec-
tion relay located in the cabinet. Inside the cabinet,
are the generator set PLC and the automatic voltage
regulator (AVR).

Figure 88. Manual control unit

7.2.4 Automatic voltage regu-

lator (AVR)
Plant network Ethernet

The automatic voltage regulator (AVR) controls the

Remore I/O bus

output voltage from the generator by controlling the

DC field current in the rotor of the excitation system.
The AVR detects changes in the terminal voltage
(caused, for example, by a sudden load change) and
varies the field excitation as required to restore the
terminal voltage of the generator. The excitation is
automatically switched on and off at a specified en-
gine speed.
Under steady loading conditions, the regulator main-
Figure 87. Devices and communication inside the tains a constant and stable generator voltage within
generator set control cabinet +/-1% of the set value. The operating range of the
generator voltage is +/-5% of the nominal voltage.
The adjustment rage for AVR is +/- 10%
7.2.2 Generator set PLC The AVR has two main control modes: voltage
The PLC (programmable logical controller) is the droop control mode and power factor control mode.
core of the generator set control system. The PLC In addition, voltage droop compensation is available.
includes a CPU (central processing unit), which con- Power System Stabilizer (PSS) is available as an op-
tains the control functions, and I/O cards of various tion.
types for collecting and transmitting process signals.
The PLC collects data from all I/O:s connected to
the IO cards, executes controls, and generates output.
7.2.5 Protection relays
Generator protection relay
7.2.3 Manual control unit
When a fault is detected the generator protection re-
The manual control unit contains selector switches lay opens the generator breaker in the main switch-
for choosing the control mode, start and stop but- gear. Wärtsilä typically uses a multi function relay
tons, manual output control switches, button and containing the following functions:
indication lamp for closing and opening the generator
breaker, and alarm lamps.

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Wärtsilä 50SG Power Plant Product Guide 7. PLANT CONTROL SYSTEM

Protection Symbol ANSI No 7.3 Common control

Over voltage, two stages
Under voltage
U>, U>>
U<
59
27
cabinet
Reverse power, two stages P←>, P←>> 32R
Under, and over frequency f<, f> 81H, 81L 7.3.1 Overview
Under excitation, two X<, X<< 40
stages
Main components
Voltage dependent over- Iv> 51V
current The common control panel contains:
Residual voltage, two Uo>, Uo>> 59N
stages · a PLC unit for centralized supervision and control
Unbalanced load I2/I> 46 of the common plant systems
Stator overload Ф> 49
· an auto synchronizer for automatic synchroniza-
Over current, two stages 3I> , 3I>> 50, 51 tion
Earth fault Io>, Io>> 50N, 51N
Table 29. Generator protection relay functions
· a manual synchronization unit containing a syn-
chronoscope, and double frequency and voltage
meters (source and target)
The generator protection relay also provides transient
recording by 12 channels with a cycle of 20 ms. Re-
cords from eight seconds before to eight seconds
after a breaker trip are stored.

Differential relay
The differential relay provides differential protection
of the generator, based on measurements in the MV
switchgear and in the generator.

Power monitoring unit

The power monitoring unit measures the phase cur-
rents and voltages, the frequency and running hours,
and calculates the active, reactive and apparent
power, the power factor, and the active and reactive
energy. The active power is shown on the indicator
on the front panel of the generator set cabinet.

Figure 89. Common control cabinet, front panel

(example)

In addition to the manual synchronization equip-

ment, the front panel contains a mimic diagram of
the plant power distribution system, and plant emer-
gency stop and reset buttons. The plant emergency
stop will affect all engine generator sets in the plant.

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Wärtsilä 50SG Power Plant Product Guide 7. PLANT CONTROL SYSTEM

If the plant contains an emergency engine generator

set (black start unit), the common control cabinet 7.4 Workstations
could also contain the starting logic for the unit.

7.4.1 General
7.3.2 Common PLC A workstation is a PC computer with a monitor, key-
The common PLC is similar to the generator set board and mouse, and HMI (Human Machine Inter-
PLCs but handles functions and units that are com- face) type software. There are two types of worksta-
mon to the entire plant. The common PLC commu- tions:
nicates with the generator set PLCs and the operator
stations via the plant network. · The Wärtsilä Operator Interface Station (WOIS),
which is a graphical user interface for supervising
and controlling the plant.
7.3.3 Synchronization units · The Wärtsilä Information System Environment
(WISE), which handles the long term data storage
Auto synchronizer and report functions of the power plant.
The auto synchronizer function integrated in the The control system may comprise one or more
AVR compares the generator frequency and voltage WOIS workstations, a WISE workstation, and one or
to the frequency and voltage of the bus bar, and ad- more printers for hardcopy and report printing. The
justs the engine speed and generator excitation to workstations must always be kept running and cannot
equalize them. When the deviations are within preset be used for other purposes.
limits and the phase difference is also within preset
limits, the auto synchronizer issues a breaker close The workstations enable remote monitoring and data
signal. To compensate for the breaker closing time sharing with external systems.
and the operation time of the output relay, it calcu-
lates required advance phase angle. For synchroniza-
tion of grid breaker, if required, the auto synchronizer 7.4.2 Operator station WOIS
located in Common Control Panel will be utilized
General
Manual synchronization set
At the WOIS workstation, the operator can monitor
The synchroscope measures the phase difference the plant and take actions, such as starting and stop-
between the generator and the bus bar and indicates ping the engine generator sets, and changing the set
with LEDs when the breaker can be closed. It also values used in the engine and generator control. The
indicates when the generator frequency needs to be operator can supervise plant key data, such as various
raised or lowered, and if the voltage difference is temperatures and pressures, as well as measurements
within set limits. The operator controls the voltage of electrical variables, for instance, generator output,
and frequency manually with switches and by super- voltage and frequency.
vising the double voltage and frequency meters on
the common panel. WOIS provides process displays, alarm and event
handling, process trends, instant reports, and control
A sync check relay prevents breaker closing if no system supervision. The user selects displays by click-
synchronization has been done, or if the synchroniza- ing on buttons in dynamic menus at the top and bot-
tion has failed. tom of the screen, or by clicking in the process dis-
plays. The most important displays are always acces-
sible at the top of the screen.

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Process displays A further evaluation of historical alarms can be done

in the event list. In addition to the alarms, the event
In the process displays, the process components are list contains all normal changes of operational state,
illustrated by graphical objects, such as images of for instance, engine start and stop and change of
pumps and valves, with dynamic status indication breaker status. WOIS events, such as change of
implemented as change of symbol or colour. By se- power set point, can also be seen in the event list.
lecting an object, the operator can access more de-
tailed data on the object, for instance, trend data of
measured values. A plant overview display provides a
clear and concise view of the entire plant.

Figure 91. Event list

Process trends
The graphical trends show measured values such as
pressures, temperatures, speed, engine generator set
load, etc., on a time axis. To get a comprehensive
view of the process, the operator can combine the
values of up to six features in one graph. The trends
are stored for up to 180 days.

Figure 90. A plant overview display, a generator set

temperature display, and an object data
window

Alarm and event handling

An alarm banner, which is always visible in the up-
permost part of all displays, informs about the latest
alarm that has occurred. The operator sees a compre- Figure 92. A process trend
hensive view of the alarm situation from the active
alarm list, which contains all active or unacknow-
ledged alarms. The alarms can also be acknowledged System security
from this list.
The WOIS workstation security system prevents un-
authorized use by requesting a password at user log
in. Each user is associated with a certain authoriza-
tion level, which determines the allowed operations.
There are three different authorization levels: Opera-
tor, Manager and Administrator.

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7.4.3 Reporting station WISE

Using WISE, the operator can view and print out
daily, monthly and yearly reports produced by the
reporting program. WISE keeps the engine and pro-
duction reports available for later study and archiving.
WISE gets the information from WOIS.
WISE provides the following functionality:

· Production reports of generated active and reac-

tive energy along with the hourly fuel consump-
tion. Daily production reports are stored for one
year. Monthly production reports (on daily level)
are stored for 5 years and yearly production re-
ports for 10 years. The production reports include Figure 93. A typical daily operation data report
minimum, maximum, average and total sum calcu-
lations for the period.
· Daily engine and plant reports of measured values,
such as bearing temperature and lubrication oil
temperature. Daily minimum, maximum and aver-
age values are generated and stored for one year.
The measurements can be viewed as trend dis-
plays, which enables long term follow-up of the
plant performance.
· Electronic log book with search possibilities for
recording of operation and maintenance activities.
The logbook automatically inserts events like en-
gine starts and stops into the logbook, along with
timestamps. The operator can also enter events
into the log book.
· Support for storage and viewing electronic plant Figure 94. A production report
documentation (manuals, layouts and drawings).

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7.4.5 Data sharing with ex-

ternal systems
Plant control system signals available in WOIS and
WISE can be transferred to external systems, for in-
stance, an existing control system or an ISO dispatch
centre, using Ethernet TCP/IP communication with
a firewall between the Wärtsilä control system and
the external system. For transferring WOIS real-time
data, the OPC protocol is used on top of Ethernet,
with WOIS acting as an OPC Server. For reading the
WISE reporting database, ODBC-SQL requests are
used.
The connection point for the external system is the
firewall, which is to be located in the Wärtsilä control
room. The firewall is supplied and configured by
Figure 95. Log book
Wärtsilä, while cabling and communication onwards
from the firewall is the customer’s responsibility.
7.4.4 Remote monitoring Alternatively, data can be transferred through cus-
tomer-supplied RTUs.
Provisions for Remote Monitoring services are in-
cluded in the WOIS and WISE applications. Depend-
ing on the communication lines and infrastructure at
the plant, these services can be offered based on a
7.4.6 Condition based main-
separate Support Agreement. tenance
The Remote Monitoring system allows the plant per- The WOIS and WISE applications contain provisions
sonnel to access the power plant’s control network for Condition Based Maintenance (CBM) services
from a PC via Internet. The system only allows “read offered by Wärtsilä. The extent of the services de-
only” access, that is, any control actions are prohib- pends on the communication lines and infrastructure
ited. The service includes: available at the plant. If applicable communication
lines and transfer methods are available, the meas-
· Real-time access to all the process information in urement data of the plant is automatically sent to
WOIS Wärtsilä on regular basis. Alternatively, the data can
be sent manually. A separate CBM agreement should
· Access to all historical trends stored in WOIS and be made for this service. The CBM agreement can
WISE also cover on-line monitoring with trouble-shooting
support.
· Access to active and historical alarm information
· Access to the log book, including present and his-
torical log book events
Remote monitoring uses standard Internet related
protocols and widely used services for secure and
reliable communication. Supported techniques for the
physical connection to the system are DSL or leased
line communication.

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Wärtsilä 50SG Power Plant Product Guide 7. PLANT CONTROL SYSTEM

Most data and signals from UNIC to the generator

7.5 Signal and data com- set PLC, for instance, engine measurements, and
munication status and alarm signals, go through the Ethernet
plant network. Likewise, the set values from the PLC
to UNIC go through the Ethernet plant network.
7.5.1 General Also, the protection relays delivered by Wärtsilä
communicate with the PLCs via the Ethernet plant
The majority of the signals communicated between network.
the engine control system (UNIC), PLCs and remote
I/Os are transferred via communication buses. How- The communication between the engine generator set
ever, all primary control signals such as AVR, speed, PLC and the remote I/O in the EAM module goes
synchronization and breaker trip signals are hard- through a communication bus using a high level
wired. Likewise, the safety related signals, such as standard protocol.
emergency stop signals and critical alarm signals are
hardwired.

7.5.2 Signal types

The signals handled by the plant control system are
of the following types:

· Analogue input signals (AI), for instance, pressure

and temperature measurements. The control sys-
tem recognizes AI signals scaled to 4 … 20 mA,
and PT100 and thermocouple temperature meas-
urements.
· Analog output signals (AO), for instance, set
points to thermostatic valves. AO signals are
scaled to 4 … 20 mA.
· Digital input signals (DI), for instance level
switches. The digital input signals must be ar-
ranged as potential-free contacts.
· Digital output signals (DO), for instance
start/stop signals. The digital output signals are
arranged as potential-free contacts.

7.5.3 Communication buses

The communication between the control room PLCs
and the engine control systems go through the plant
network. The plant network is a standard local area
network using Ethernet TCP/IP and twisted pair
cables, or fibre optics if the distances are longer than
100 meters. The Ethernet switches are located in the
control cabinets.

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7.5.4 Hard-wired signals

Engine-specific signals
The following figure illustrates the engine-specific
hard-wired signals.

Common control panel

Emergency stop
Engine load Engine
Generator breaker status control
Busbar breaker status system
Shut-down (UNIC)
Critical alarms Gas
Ready for start pressure
setpoints
Control of shut-off valves
And vent valves CGR
Pressure
Temperature
Leak test status
Vent fan control Exhaust
gas
Emergency stop Running inform. module
EAM
Control signals to
panel
three way valves
Diff press. alarm Intake
air filter
Temperature readings
MCB open signals etc. Generator

Breaker control etc.

Figure 97. Overview of common hard-wired signals
Breaker status MV switchgear
Truck position etc. (example)

Ground disconnector
status Neutral point cubicle

Remote start/stop 7.5.5 Control cables

Frequency control
Radiator system
Running indication The cables should be PVC insulated copper cables.
Common alarm
They must not absorb static or magnetic noise signals
Motor status signals Annunciator from the surroundings.
Vent fan motor control
Roof fan monitor control Signals of the same type can be contained in the same
Ventilation system
Running indication
Filter diff. pressure
cable. Signals of different voltages require separate
cables.
Figure 96. Overview of engine-specific hard-wired
signals (example)

The hard-wired signals between the instrumentation

within the EAM module and the EAM cabinet are
factory installed and not shown in Figure 96.

Common signals
The following figure illustrates the amount of hard-
wired signals that are common to the plant.

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7.6 Functional description Normal stop

At a normal stop request, the generator set PLC
unloads the engine according to a specified ramp and
7.6.1 Start and stop processes opens the generator breaker. Then it shuts off the gas
supply from the compact gas ramps to the engine,
Start and sends a shut-down command to UNIC. When
the engine has stopped, the PLC starts the exhaust
At an engine start command, the generator set PLC gas vent fan, and ensures that the ventilation is done.
checks that the generator, engine and auxiliary sys- The engine cannot be restarted until the exhaust gas
tems are ready for start, for instance, that the genera- ventilation fan has been operated.
tor breaker is open, starting air and control air is
available, lube oil inlet pressure is high enough, HT- Synchronization
water outlet temperature is high enough, and the
turning gear is not engaged. Provided that all start The generating set is started by pressing the engine
conditions are fulfilled, the PLC activates gas system start button on the WOIS workstation. UNIC and
tightness check, and sends a start command to the the PLC will run through the starting sequence, and
engine control system (UNIC). the PLC initiates the automatic synchronising han-
dled by the AVR. Once the generator breaker is
closed, the engine will be loaded to the level which is
set in the WOIS workstation. The engine will be run-
ning on base load. Synchronization and breaker con-
trol can also be manually initiated from the mimic
diagram.

7.6.2 Output control

Engine speed and load control
The PLC controls the engine speed and load by send-
ing set values to UNIC according to the active con-
trol mode: kW control mode or speed droop.
In speed droop control mode, the speed - load rela-
tionship will follow a linear speed droop curve de-
fined in UNIC. Generally, the speed droop setting is
4%.

Figure 98. Typical overview of the starting condi-

tion check and main start/stop se-
quence

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The prescheduled output is stated as the output to be

produced when grid frequency is at scheduled value.
This prescheduled output typically is a constant or a
ramp at a preset rate. In this mode a generating unit
provides primary response on a sustained basis when
grid frequency changes
In isochronous load sharing control, the genera-
tors sets will operate at a constant frequency regard-
less of the load they are supplying, up to the full load
capability of the generators. Load sharing lines
(CAN-bus) are required between the speed control-
lers (UNIC) in order to share the load between the
paralleled units.
Speed droop control is enabled in island operation,
and in the MANUAL mode, also in parallel opera-
Figure 99. Speed droop graph (speed droop 4%, tion. The kW control mode is enabled in parallel op-
speed set point 51 Hz) eration only. The isochronous mode is only enabled
in island operation. The operator selects a control
The operator can change the set point at a work- mode on the control panel. The control system will
station or with a switch at the control panel. Auto- also automatically switch control mode when the grid
matic fine tuning of the frequency is available as an breaker is opened or closed.
option in the generator set PLC.
Generator output control
In the kW mode, UNIC maintains the engine power
constant. The set value can be changed from an op- The generator voltage and reactive power (power
erator station or the control panel. A true kW con- factor) are controlled by the automatic voltage regula-
trol, such as the Wärtsilä kW control, will not try to tor (AVR) according to the chosen mode – voltage
control the speed, rather it will look at the generating droop, voltage droop compensation, or power factor
set output directly and match it to a given reference, control mode – and set values from the generator set
therefore kW control is not affected by frequency PLC.
changes in the grid and a steady base loading is
achieved. kW control is only possible when running In the voltage droop control mode, the relationship
in parallel with the grid (system frequency control voltage - reactive load follows a linear droop curve.
must exist). The droop setting, that is, the voltage drop when the
reactive load is increased from 0 to 100%, is adjust-
For frequency support there is an additional opera- able and is normally in the range 1 ... 10 %. To main-
tion mode: tain the voltage at an increased load, the operator can
change the voltage reference (set value) in WOIS or
Frequency compensated kW control fixed MW with a control switch. The optional Master Voltage
control with frequency support for strong grids Control function changes the voltage reference
automatically.
A controller applies secondary control commands
(KW or MW set-point) to the governor speed-load Voltage droop compensation is used to share the
reference to hold the plant or generating unit at a reactive power equally between parallel engine gen-
prescheduled output with the prescheduled output erator sets in the island mode. The AVR compensates
being biased by deviation of grid frequency. for the voltage droop to keep the voltage at 100%.
Voltage droop compensation requires an RS-485 bus
connection between the AVRs.

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Power factor control means that the AVR will adjust 7.6.3 Control of auxiliary sys-
the generator excitation current in such a way that the
Power factor (cosine phi) of the generator output tems
remains constant at a set value.
Engine specific auxiliary systems
The power factor control mode can be used only dur-
ing parallel operation. Voltage droop can be used in The engine specific auxiliary equipment, except for
both parallel and island operation modes, but is nor- the radiators, are supervised and controlled via the
mally used only during island operation. Voltage control panel in the engine auxiliary module (EAM).
droop compensation is only available in the island The panel controls start and stop of pumps and heat-
mode. The operator selects a control mode from the ers. The thermostatic valves in the cooling water sys-
control panel. The control system will also automati- tem are controlled centrally from the engine genera-
cally switch the control mode based on the grid tor set PLC. The PLC receives cooling water tem-
breaker position. peratures from the EAM module and sends set points
to the three way valves.
Power management functions The radiators are controlled directly from the genera-
With the power management functions, the operator tor set PLC. The PLC sends set points to the fre-
can order a plant output power at a workstation. The quency converters in the radiator control panels
control system shares the ordered power equally be- based on measured temperature in the return line.
tween the running generator sets, and sets the engine-
specific load references accordingly. Common auxiliaries

If the ordered load exceeds the capacity of the run- Common auxiliaries are controlled by local panels.
ning generator sets, there will be an alarm requesting Running signals and alarm signals are sent to the
the operator to start up more generator sets. As an common plant control panel.
option, automatic start and stop of generator sets
may be included.
7.6.4 Safety functions
Another power management option is the load fol-
lowing system. Load following helps the operators General
plan the generation load pattern according to the
power need, the imported energy, and other factors The automatic safety functions work in the same way
such as system losses. The system is implemented in in manual and automatic mode.
WISE, WOIS and the common PLC.
Alarm sources and alarm indication
Load shedding
Alarms can be initiated in the control room panels, in
The plant can be provided with a load shedding UNIC, in the EAM panel, and in the local panels of
scheme, which will be activated when the consump- the common auxiliary equipment. All alarms are indi-
tion tends to increase over the capacity of the plant. cated in the control room, either as individual alarms
Load shedding is applicable during island operation or group alarms (common alarm), and local alarms
only. are also indicated at the local panels. Engine alarms
are also indicated by light signals in the engine hall.

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Engine load reduction and de-rating Emergency stop

Bad operating conditions that do not require an en- An emergency stop activates an immediate shut-
gine stop will activate a load reduction alarm upon down of the engine. An emergency stop of an engine
which the operator should reduce load. Automatic can be activated with a push button on the generator
load reduction (de-rating) takes place when de-rating set panel. An emergency stop is automatically acti-
is required due to ambient conditions. The PLC will vated when an emergency mode has been activated in
lower the load set point sent to UNIC. UNIC can UNIC, for instance at over-speed. An automatic
also activate a load reduction in risky situations. emergency stop is also activated if a wire break is de-
tected in an emergency stop cable.
Automatic shutdown
A plant emergency stop can be activated from the
Highly critical or urgent occurrences will activate an common control panel and will affect all engines.
immediate shut-down of the engine without unload-
ing. A shutdown may be initiated by UNIC or by the Depending on local rules and regulations, the control
generator set control system. In case of an engine system can be programmed for an automatic plant
initiated shutdown, the PLC shuts off the gas supply emergency stop in the following situations:
to the engine immediately. The main consequences of
· A gas detector senses 20 % of LEL (lower explo-
a shut-down are:
sion limit)
· Generator breaker opens. · A fire detector is activated
· Stop command is sent to UNIC. Alternatively, the activation of a detector only causes
· Compact gas ramp is closed. an alarm and the operator takes the necessary actions.

The shut down cause will be noted in the WOIS

alarm list.

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Wärtsilä 50SG Power Plant Product Guide 8. PLANT LAYOUT

8. PLANT LAYOUT

· Fire protection spaces

8.1 Site layout
· A possible black start unit with fuel storage tank
· Stormy water pond if needed
8.1.1 Site Layout principles
· Possible water treatment unit and water tank
The following primary facts should be considered
when arranging the site layout: · Possible sewage water treatment

· The size, shape and topography of the site · Roads and parking lots, access roads, and turning
places for transport vehicles
· The location of the power transmission lines
· Reservations for possible future expansions
· Soil conditions
· The location of the gas supply pipe. 8.1.2 Site layout notes
The location of the power transmission lines may be
The performance of the cooling radiators, and thus
decisive when determining the placement of the
the performance of the plant, is greatly affected by
switchyard, and it may affect the orientation of the
the airflow to the radiator field. The radiators can be
entire plant. Generally, the switchyard is located on
located on the roof of the engine hall or on the
the generator side of the engine hall and the radiators
ground.
on the engine side of the engine hall.
Space should be reserved for: Radiators on the roof

· The engine hall which can include service rooms, The preferred and most effective way to ensure suffi-
administration rooms and electrical rooms cient air exchange around the radiator field is to in-
stall the radiators on the roof of the engine hall. The
· Any separate service buildings, like administration radiators will perform regardless of wind direction,
building, electrical room, workshops, and storage while site foot print constraints and the location of
tanks and other sizeable objects is less of an issue
· Exhaust gas pipes and stacks, including possible compared to sites with ground installed radiators.
heat recovery and emission control equipment
Minimum radiator leg height above the roof ridge (h)
· The radiator field with switchgears and frequency
converters, or possible cooling tower W18V50SG 3600mm
· The switchyard and possible outdoor transformers
· Tank yard and loading/unloading station
· Oily water sumps
· Gas pipes above ground, main valves and a possi-
ble pressure reduction station
Figure 100. Radiators on the roof
· Fire equipment house, and possibly a fire fighting
water tank and pumps

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Radiators on the ground In order to minimise the risk for hot air recirculation,
the radiators should be grouped together tightly to
To ensure the air flow to the radiators, they should be form a uniform field. If gaps between the radiators
installed at such a height that the vertical radiator air can’t be avoided, they should be covered with hori-
inlet face area equals or exceeds the horizontal radia- zontal metal sheets or similar. Other factors that af-
tor inlet face area (=radiator footprint). However, the fect both the air flow and possible re-circulation are
minimum height above ground should be 2m.
Wind speed and direction
In case of possible noise walls around the radiator
field, they have to be placed at a distance of 3 times Site topography
the radiator installation height.
Buildings, vegetation, tanks etc
The distance between radiator field and adjacent size-
able objects (like the engine hall) should be as long as Tank yard and unloading station
possible. For plants with less than 5 generating sets,
the minimum recommended length = 2,5 times the The tank yard and unloading station should be lo-
building height. For larger plants the following for- cated in an area where the risk of fire is small. It must
mula is recommended, which yields a longer distance also be ensured that it will impose no hindrance for
the operation of the fire protection system in case of
p-h a fire accident. Fire fighting regulations as well as lo-
d≥ , dmin =2,5×p cal regulations must be followed.
tan 7°
where: Other factors to consider are the location of other
buildings nearby, and access from road, railway or
d = distance between engine hall and radiator field waterway for filling the tanks.
[m]
The unloading station must be located in the open air
p = engine hall height [m] next to the tank yard.
h = radiator field free height above the ground [m]
Administration buildings
If the control room is placed in a separate building,
maximum control cable length must be considered.

8.1.3 Site layout examples

Figure 101. Radiators on the ground Below are presented typical layouts for 6 and
12xW18V50SG power plants. Smaller plants usually
The possible re-circulation of hot air will reduce the have one common building including engine hall,
capacity of the cooling radiators and must therefore control room and electrical room. Bigger plants usu-
be avoided. A reduced air flow will also increase the ally have separate administration building, separate
risk of re-circulation and combined, these issues control and electrical room and separate workshop.
would affect the cooling capacity considerably.

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Figure 102. Typical site layout for a 12xW18V50SG plant in two separate engine halls

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Wärtsilä 50SG Power Plant Product Guide 8. PLANT LAYOUT

Figure 103. Typical site layout example for 12xW18V50SG Flexicycle plant

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Wärtsilä 50SG Power Plant Product Guide 8. PLANT LAYOUT

Figure 104. Typical site layout example for a 24xW18VW50SG Flexicycle plant

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Wärtsilä 50SG Power Plant Product Guide 8. PLANT LAYOUT

8.2.3 Layout notes

8.2 Engine hall layout Air intakes

Air intakes should be in a dust free location and
therefore as high as possible, still accessible for main-
8.2.1 Engine generator set tenance. The intake should be placed away from heat
distance sources such as exhaust gas pipes, ventilation outlets,
etc.
The following figure shows the space required for the
engine generator sets. The recommended distance Expansion vessels
between adjacent engine generator sets, from centre
to centre, is 7200 mm. The expansion vessels must be located above the
highest part of the cooling water system. When radia-
tors are mounted on the roof, they must be moved
from the exhaust gas modules to a higher location.

Air compressors and tanks

Air compressors must be installed in a well ventilated,
dust free, freezing free and water free area. The com-
pressed air tanks should be located close to the con-
sumers to avoid large pressure drops in the pipes.

Figure 105. W18V50SG EG sets with service plat-

Lube oil pump unit
forms. The lube oil pump unit should be situated as close as
possible to the lube oil storage tank.
The standard modules are designed to be intercon-
nected with service platforms in between – the engine Maintenance water tank
auxiliary modules on floor level and the exhaust gas
modules above. Six EAM modules can be connected The maintenance water tank should be placed as low
in parallel and use common header pipes. as possible to allow drainage of the water.

Transportation and maintenance space

8.2.2 Other space require- The engine hall should have space for transporting
ments main components to and from the engine.
Space must also be reserved for: The possibility should be maintained to make an
opening in the wall on the generator side of the en-
· Common auxiliaries, as compressor units and gine hall for replacing a generator or entire engine
compressor air tanks, maintenance water tank(s), generator set. There should be no fixed structures,
lube oil pump unit(s), etc. such as pipes or cable ladders mounted on this wall.
· Pipes, cables, pipe and cable supports, fire fighting
hoses, sprinklers, electrical fittings, etc.
· Maintenance areas and transportation routes.

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8.2.4 Layout example

Figure 106 shows a layout example of an engine hall
and the exhaust gas systems. The engine generator
sets along with their compact gas ramps, engine auxil-
iary modules, and exhaust gas modules are grouped
six and six. The free space is utilized for maintenance
water tanks and air bottles, and as maintenance and
lay down area.

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Wärtsilä 50SG Power Plant Product Guide 8. PLANT LAYOUT

Figure 106. Typical W50SG Engine hall layout

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Wärtsilä 50SG Power Plant Product Guide 8. PLANT LAYOUT

8.3 Electrical equipment 8.3.2 Electrical rooms

building The medium voltage switchgear, the main LV switch-
gear, distribution boards, possible motor control cen-
tres and the DC system must all be situated indoors
in electrical rooms with air conditioning. To permit
8.3.1 General shortest possible wiring between the generators and
The requirements for other spaces in the power plant the medium voltage switchgear, it is recommended to
building – switchgear rooms, control room, offices, locate the switchgear at the generator side of the en-
workshop, social rooms, etc. – depend on the owner's gine hall.
requirements and the operating profile of the plant. Depending on the type, the station transformer can
Figure 107 shows an example of an electrical equip- be placed indoors or outdoors.
ment building.

Figure 107. Electrical equipment building for 12 x W18V50SG(example)

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Wärtsilä 50SG Power Plant Product Guide 8. PLANT LAYOUT

8.5 Pipes and cables

8.4 Tank yard and
8.5.1 Pipe layout
unloading station
To minimize the pressure drop in the pipes, pipe runs
should be as simple and direct as possible. To sim-
8.4.1 Tank yard plify supporting and improve appearance, the pipes
are generally arranged parallel to building steel work.
The tank yard contains the lubricating oil tanks, the
oily water tanks, and possible reagent tanks for SCR. Factors to consider when reserving space for pipes
The water tanks may be located in the tank yard. are the pipe diameter, possible insulation, minimum
distance between pipes, and minimum distance be-
The distance between the tanks, as well as the dis- tween pipes and walls or bars. Also the need for
tance between storage tanks and the toe of the stor- maintenance space and access to equipment should
age tank area dike wall must obey the applicable stan- be regarded.
dards and local regulations.
There should be separate containment areas for tanks
containing oil and water solutions (SCR reagents) as 8.5.2 Cabling
they should not be mixed in case of a leakage. Cabling routes must be selected in such a way that
the cables will not cause disturbances to other sys-
tems. It is recommended to run the cables between
the generators and the main switchgear in cable con-
duits under the floor
Low voltage cables and control system cables are car-
ried by cable ladders, separate ladders for control sys-
tem cables and power feeder cables. Where applica-
ble, the pipe supports can be used as supports for the
cable ladders.

Figure 108. Tank yard example

8.4.2 Pump shelter

The pump shelter contains unloading pumps with
control panels for lube oil and sludge, possibly also
Urea or ammonia in plants with SCR.

Figure 109. Cable ladders

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8.6 Hazardous areas IEC

60079
NEC
505
NEC 500 Explanation

Zone 0 Class I, Class I, An ignitable mixture

zone 0 division 1 is present continu-
8.6.1 General ously

A hazardous area is a location where the atmosphere Zone 1 Class I, An ignitable mixture
zone 1 is present intermit-
contains or may contain a combustible material, such tently
as fuel gas, in sufficient concentration to form an
Zone 2 Class I, Class I, An ignitable mixture
explosive or ignitable mixture. zone 2 division 2 is not normally pre-
sent, but may be
In hazardous areas, it is important to avoid all poten- present under ab-
tial ignition sources, including electrical and mechani- normal conditions
cal equipment which could form sparks and hot sur- and then only for a
faces. The primary recommendation is not to install short period of time
or use any equipment in these areas. When this is not Table 30. Classification according to the IEC and
practicable, certified equipment must be used. NFPA70 (NEC) standards

The hazardous areas are classified to determine the

Figure 1 shows a typical example of the hazardous
level of safety required for the electrical and me-
area classification of an engine hall with lean burn gas
chanical equipment installed or used in the areas. The
engines. The indicated hazardous areas are spheres
classification and the required or recommended pro-
around the potential release points.
tection methods are based on standards and direc-
tives. In Appendix A are listed the most commonly
used standards for the classification of hazardous
areas and for the requirements placed on equipment
installed or used in classified areas. In addition, local
requirements must always be met.

8.6.2 Classification of haz-

ardous
areas
The classification of hazardous areas is based on the
likelihood of an ignitable gas mixture being present.
Table 30 lists the principles for defining hazardous
areas according to European and American stan-
dards, IEC 60079 and NFPA 70 (NEC) respectively.
“Class I” in the NEC designations refers to gas (class
II is dust and class III fibres). Figure 110. Classification of hazardous and re-
stricted areas during operation in a gas
Ignitable gas mixtures may form when fuel gas is re- engine power plant, according to the
leased from the fuel gas system into the surrounding IEC and NFPA standards (example)
air. Hazardous areas are therefore classified where
release of gas may take place, which happens from
points referred to as sources of release or possible
sources of release.

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The engine itself is not considered to be a source of 8.6.3 Protection methods in

release, provided that the ventilation in the engine
hall is adequate. All flange joints, valves etc. in the hazardous areas
external fuel gas system are considered to be potential Within hazardous areas, it is mandatory to use only
sources of release whereas welded pipe isn’t. Gener- suitable, certified devices. The requirements are de-
ally, in a Wärtsilä designed power plant, the only units termined by the properties of the gas. The normal
inside the engine hall containing possible sources of gaseous fuel, natural gas, is classified as a group IIA
release are the compact gas ramps (CGRs). A limited (IEC 60079 / NEC 505) or group D (NEC 500)
sphere shaped space with a radius of 1 m (3.3 feet) flammable gas. The auto-ignition temperature for
from the possible sources of release in each CGR is natural gas is often considered to be the same as for
consider to be a zone 2 hazardous area. the base component, methane, which is 537°C
Outside the engine hall, the spaces around the gas (999°F). The actual auto-ignition temperature for
system vent pipe outlets are hazardous areas. most natural gases is higher due to inert constituents.

In a gas plant, the tank yard is not a hazardous area. There are different explosion-protection techniques
for electrical equipment. Unless local rules impose
During maintenance and repair work, additional areas stricter requirements, Wärtsilä follows either the IEC
may need to be classified as hazardous. or NFPA standards. Table 31 shows some typical
protection methods for equipment installed or used
If the plant contains other sources of release not re- in hazardous areas in a gas power plant.
lated to the Wärtsilä engines, they must be analyzed
and considered as well.

Device Typical protection method

Instruments and Ex i Intrinsic safety
control devices
Electrical motors Ex d Flameproof
Electrical heaters Ex d Flameproof
Junction boxes Ex d Flameproof and
Ex e increased safety
Table 31. Typical protection in hazardous areas

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Wärtsilä 50SG Power Plant Product Guide 9. SITE, CIVIL WORKS AND STRUCTURES

9. SITE, CIVIL WORKS AND STRUCTURES

Risk for seismic activity will have a considerable im-

9.1 Site considerations pact on all plant design and installations. All build-
ings, structures and installations must be designed
according to applicable regulations for the seismic
conditions.
9.1.1 Site selection criteria
The following factors, which may have an impact on · Soil conditions
the construction costs, plant performance, and pro- The soil conditions should appear from the geotech-
duction economy, should be considered when evalu- nical investigation, see below. Local soil improvement
ating the appropriateness of a site: or piling may be needed.
· Size requirements · Ambient conditions
The size requirements are determined by the site lay- Possible risks for hurricanes, flooding and sand
out. On the other hand, the site layout can be ad- storms must be regarded in the design of the plant.
justed to suit the available site. Also, in coastal areas with salt laden air, additional
Also to be considered is the need for a lay down area corrosion protection of outdoor structures may be
needed.
and space for site offices in the immediate vicinity of
the plant during the construction phase.
· Access by road, railroad, or waterway
· Proximity to power and heat consumers When evaluating road connections, the largest trans-
For economical reasons, the plant should be located portation weights and sizes, required road width, pos-
sible sharp curves, and the bearing capacity must be
as close as possible to the load centres, electrical
transmission lines, and potential users of waste heat taken into account. The roads must fulfil local trans-
portation regulations regarding design width and
(if heat recovery is included).
minimum radius of road curves.
· Environmental issues and building permits
The type of neighbourhood – industrial area or hous- 9.1.2 Geotechnical investiga-
ing area, for instance – has a considerable impact on tion
allowed noise, air emission levels, rain water issues,
aesthetic values, acceptable levels of pollutants during A detailed geotechnical investigation, including in-
the construction phase, etc. formation on topography, terrain, seismic conditions
and soil conditions is necessary for evaluating the site
· Available connections and deciding on required earth work.
The nearness to fuel gas pipes is of vital importance. The topography is of importance for the site layout,
Important, although less crucial, is the existence of grading and drainage. The risk for earthquakes in an
utility connections, such as clean water and sewage area is indicated by the seismic zone, zone 0 repre-
water pipes, and telephone communication. senting the lowest risk level and zone 4 the highest.
The a.m. classification of the earthquake zoning is
· Seismic conditions according to Uniform Building Code 1997.
The soil investigation should determine the following
soil conditions:

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· Density and bearing capacity The site should be sloped to carry all surface water
off the site or to the retention pond. In case of a flat
· Dynamical properties site, the powerhouse must be raised above the exist-
ing ground level according to local regulations. If the
· Hydrocollapse potential and liquefaction site is located in a flood area, all structures must be
· Plastic limit, liquid limit and swell potential in co- raised above the maximum flood height.
hesive soils
· Potential to corrode steel, or to adversely react 9.2.3 Underground utilities
with concrete
Underground utilities include:
· Soil resistivity (suitability for electrical earthing)
· Gas pipes
· Presence of groundwater, percolation.
· Pure water, fire water and sewage pipes
Minimum allowable soil bearing pressure must be
determined from case to case. · Oily water pipes for conducting oily water to the
oily water sumps
· Underground conduits for electrical cables, with
support structures if valid regulations so require
9.2 Earthworks and site
· Grounding grid.
works
Local regulations must be followed.

9.2.1 General
The required earth works is based on the geotechni-
cal investigation and locally valid regulations. Earth 9.3 Engine hall foundation
works generally comprise excavating and compacting
soil, and grading. Depending on the soil quality, it
may also involve soil replacement, soil improvement, 9.3.1 General
blending, various compaction techniques and piling,
as well as the use of a geomembrane between layers As standard, Wärtsilä uses a shallow foundation with
of different soil types. If the soil quality so allows, the reinforced ground floor slabs strengthened with
foundations can be laid on well drained and com- beams along the column lines of the building. This
pacted structural fill. solution is suitable at sites, where the bearing capacity
is at least 150 kN/m2 at 0-level and there is no set-
Regarding roads and pavements, they must fulfil lo- tlement or swell risk.
cally valid rules and transportation regulations.

9.2.2 Site drainage

The objective of the drainage is a controlled removal
of rainwater from the site. Local regulations may re-
quire the rainwater be collected to a retention pond.
The drainage system, and the rain water pond (if re-
quired), should be sized for the design rain in the re- Figure 111. Engine generator set foundations and
gion according to local regulations. beam strips

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The static loads on the foundation are the weight of The foundation of the engine generator set must be
the equipment and the support reactions from the in accordance with Wärtsilä’s design or approved by
buildings and structures. Wärtsilä.

Note! The planned route for hauling in the The engine generator set foundation is a block, which
engine generator sets during installation must be is cast in a single continuous pour. It is separated
strengthened to carry the engine generator sets. from the surrounding floor slab with an elastic joint.
A drain channel connected to an oily waste collection
sump runs around the block. See Figure 113.
9.3.2 Engine generator set For dimensions and details, see Figure 114. The fig-
foundation ure applies at sites where no piling is needed. A
deeper block is required at sites where piling is neces-
With steel springs under the engine generator sets, sary.
the dynamic forces and vibrations acting on the
foundation are close to zero.

Figure 112. Typical engine hall foundation

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Figure 113. Cross section of the engine hall foundation

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Figure 114. Engine generator set foundation drawing

9.3.3 Material and strength 9.3.4 Floor tolerances

Unless local exposure conditions or local regulations The following figure shows the tolerance require-
set stricter requirements, the foundations shall be ments for the zones under the engine generator set
made of grade C20/25 concrete reinforced with high feet.
yield deformed reinforcing bars with minimum yield
strength fy = 400 N/mm2. For the foundation under the auxiliary module, the
tolerance is ± 5 mm.
The required load bearing capacity of the floor slabs
outside the engine generator set foundations is 10
kN/m2 for spread loads and 40 kN/m2 for point
loads, applied on a defined area.
For quality requirements, refer to applicable building
codes.

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Special tolerances:
9.4 Other foundations
Tolerances for inclination on the hatched area:
(Both directions)

9.4.1 Tank yard and pump

Surface level difference between any two points
station
(Inside one area or between the two hatched areas)
The tank foundations are normally ring beams filled
with fine sand or similar material. They are made of
concrete and about 200 - 500 mm (8 - 20 inch) thick,
depending on whether anchorage is needed or not.
The need for anchorage is determined by local regula-
tions and depends on the height of the tank, wind
General tolerances:
For line and level in general: +5/-5 mm
conditions and seismic conditions, etc.
For dimensions in general: +10/-5 mm
Generally, according to applicable standards and
Figure 115. Floor tolerance for the engine generator building regulations, the tanks must be located inside
set (helical springs = hatched area) a concrete basin type containment area sized to hold
the volume of the biggest tank plus a safety margin.
9.3.5 Floor drains There should be two different collecting systems, one
for drained water and possible oil leakages, and one
For drain collection, there are the following alterna- for rain water. The operator decides whether to
tives: empty the containment area to the rain water drain
system or the oily water sump.
· A long drain channel running under the row of
EAM modules with one or several collection pits
· A short channel with a collection pit per engine. Service Platform
Drain valve

The floor should slope slightly towards the floor

drains.
Typical dimensions of the drain channels: Rain To oily water tank
water
drain LS

width = about 300 mm Rain water channel /

LS

collection pit Oily water sump LS

depth = about 200 mm with a slope of 1:100 to

the collection pit. Figure 116. Tank yard oily water and rain water col-
lecting systems

9.3.6 Surface treatment The platform of the pump station must be designed
with drain grooves and drain pit according to local
The upper surface should be coated with an Epoxy standards and regulations.
paint (or hydrocarbon resistant paint) to prevent con-
tamination of the concrete.
9.4.2 Stacks, radiators and
transformers
The stack, radiator field and transformer foundations,
are sized in accordance with the soil study results and
the weight of the equipment.

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The foundations of oil filled transformers are typi- The standard wall panel used by Wärtsilä is an insu-
cally built as a containment area. Depending on local lated, lightweight, sandwich type construction where
regulations, a containment area may also be required the surface metal sheets are bonded by glue to the
under the radiator field if glycol mixed water is used. rock wool. The exterior surface is made of galva-
nized, substrate coated, mouldable steel sheet with
polyvinylchloride coating. The wall is fire resistant
and non-combustible.
9.5 Frames, outer walls and
roofs

9.5.1 General
Local building regulations determine the loadings that
the building must be designed to withstand. Factors
to be considered include local weather conditions,
risks for earthquake and hurricanes, as well as other
dead loads, live loads and design loads.
The fire resistance of the building must fulfil national
or local regulations.

Figure 117. Standard wall panel

9.5.2 Engine hall
The Wärtsilä standard engine hall building is normally The standard roof consists of load bearing steel
a steel structure with a braced frame in both transver- sheets, noise and heat insulation and water proofing
sal and longitudinal direction. There’s one row of corrugated steel sheet.
columns in the centre of the hall for the support of
In projects where the radiators are located on top of
the charge air and exhaust gas systems as well as the
the engine hall, the roof is made by pre-fabricated
overhead crane beam. roof elements. The water proofing can be either by
Alternatively, a frame is used instead of columns corrugated steel sheets or a liquid roofing system
(Figure 118), and the ends are fastened with joints based upon a polyurethane membrane or an acrylic
(“Free standing building”). resin/hydrocarbon polymer compound.

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Figure 118. Steel structures for a braced frame building

9.5.3 Auxiliary structures

9.6 Interior structures
Stacks
The main function of the stack is to conduct the ex-
haust gases to such a height that the emissions meas- 9.6.1 Inner walls, floors, and
ured for a specific area are according to the local ceilings
regulations. Required stack height depends on the
dispersion of the stack emission, which depends on Wärtsilä typically designs switchgear floors with
the stack design, topography, wind conditions, and raised floor with at least 1600 mm space underneath
number of engines in the plant. to pull cables, etc.

Stacks can be arranged as a clustered stack with sev-

eral exhaust gas pipes grouped together or individual 9.6.2 Lifting and transporta-
stacks for each engine.
tion arrangements
Exhaust gas pipe support structures For maintenance purposes, it is recommended that
the engine hall is equipped with a suspended travel-
The exhaust gas pipes must be supported as required
ling overhead crane that reaches all engines, with a
by the load of the pipes considering the static forces
capacity of minimum 2 tons.
from the weight of the pipes, the vibrations from the
engine, and thermal and pulsating forces.

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Air intakes and outlets

The engine hall in a Wärtsilä designed plant has three

ventilation units per engine generator set, one at the
auxiliary side and two at the generator side of the
building. The air outlet openings are generally located
on the roof. The ventilation outlets can be continu-
ously open, manually opened and closed, or opened
and closed with locally or remotely controlled mo-
tors, dependent on the climate.

Figure 119. Travelling overhead crane

9.6.3 Stairs, catwalks and

landings
As standard, stairs catwalks and landings are con-
structed of galvanized steel gratings built on frames.
Applicable labour codes and standards must be fol-
lowed. Figure 120. Ventilation of engine hall

Gratings and ladders must not be fixed to the engine

generator set. Optionally, exhaust air fans are used. In these cases,
the inlet and outlet fans must be interlocked to en-
sure that the exhaust air flow follows the intake air
flow. Maximum over pressure in the engine hall is 50
Pa.
9.7 Heating, ventilation and
The air intake louvers should be designed to prevent
air conditioning rain water and dust from entering the system. If the
environment is heavily polluted, a high performing
filtering system is needed. In arctic climate, a heater
9.7.1 Process ventilation element can be placed in the inlet chamber to preheat
the ventilation air to about +5 °C.
General
Air change rate
The ventilation of the engine hall can be classified as
process ventilation. The basic design principles are: The prerequisite for the engine hall being unclassified
area regarding explosion safety is that the ventilation
· to remove the heat produced by the engines, gen- shall be adequate at all times according to valid regu-
erators, auxiliary equipment and electrical equip- lations. According to API500, the minimum demand
ment is 6 air changes/hour and 18m3/h per m2 building
area. To meet the heat evacuation demand, described
· to change air according to applicable standards in the following section, the ventilation in a Wärtsilä
designed plant normally achieve up to 50 room vol-
· to prohibit environmental dust from entering by
keeping the hall slightly pressurized. umes air changes per hour.

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The minimum ventilation must be on at all times as Process ventilation units

long as the equipment in the enclosed classified area
contains gas. However, if the gas supply to the engine In plants built by Wärtsilä, the engine hall ventilation
is closed outside the engine hall, no ventilation is re- units are equipped with axial fans, which are compact
quired of an engine in standby mode. and easy to maintain. The inlet fans can either be
started manually, or each fan can be started automati-
Heat evacuation cally at start-up of the respective engine. The engine
ventilation fans are equipped with frequency con-
The Wärtsilä design target is to restrict the tempera- verter control, which gives enhanced flexibility, re-
ture increase in the occupied zones of the engine hall duced electricity consumption and increased comfort.
to a maximum of 10°C above the ambient tempera-
ture in hot climates. Due to stratification, 10°C tem-
perature increase in the occupied zone means that the 9.7.2 Comfort ventilation and
total temperature increase in the hall from inlet to
outlet is in the range 14 - 17°C.
air conditioning
General
The comfort ventilation covers the control room,
possible offices and restrooms, and the electrical
rooms. The main task of the comfort ventilation is to
restrict the temperature and maintain air-changes.
The basic design principles are:

· to change air according to the rate prescribed in

locally applicable laws or regulations (for instance,
American Society of Heating, Refrigerating and
Figure 121. Example of a computerized modelling Air-Conditioning Engineers, ASHRAE)
of engine hall temperatures related to
the intake air temperature · to remove the heat dissipated by the electrical
equipment and heat loads caused by sun radiation
The ventilation air should be equally distributed in and people
the engine hall considering air flows from points of · to keep the air-conditioned rooms slightly pressur-
delivery towards the outlets. ized to prohibit moisture from condensing in the
For estimating the total heat to be evacuated, all heat constructions.
sources should be considered. The heat losses from
the engine generator set depend largely on the load. Ventilation of electrical rooms
For an estimation of the heat radiation, see the tech-
The electrical rooms must be equipped with air con-
nical data tables in chapter 11. The heat emission
ditioning systems if the temperature cannot otherwise
from the engine auxiliary module can be estimated to
be kept below 30°C. These rooms are not considered
be 10 kW.
as continuously occupied. The air conditioning sys-
tem is generally handled by roof top units with back-
up arrangements, usually two independently operat-
ing units. The AC system is to be sized according to
the heat dissipation from the electrical equipment.

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Ventilation of DC room 9.8 Fire protection

During the charging process, hydrogen gases will be
released from the DC batteries. If the batteries are
metal enclosed, the gases must be conducted to well 9.8.1 General
ventilated surroundings. Due to the explosion risks,
the ventilation air from the DC enclosures or DC Fire protection is a combination of passive and active
room should have separate outlet ducts. methods. Passive fire protection comprises safety
distances and fire barriers to ensure structural integ-
The medium voltage switchgear may require arc gas rity and limit the spread of fire. Active fire protection
exhaust ducts depending on local standards and the includes detection and alarm systems as well as fire
manufacturer’s recommendations. extinguishing systems.

Ventilation of control rooms and offices Wärtsilä defines two standard levels of fire protec-
tion, base level and extended level, which differ
Control rooms and offices are considered as normal mainly in the extent and capacity of the fire extin-
offices, and the comfort ventilation is handled ac- guishing system. In a gas plant, the extended level is
cording to the requirements in valid regulations (for recommended. The fire protection system design is
instance, ASHRAE 55 and 62). The air conditioning based on a fire risk evaluation and the NFPA stan-
is handled either by a roof top unit arrangement or by dards which are used as guidelines.
a separate, modular, unit. Generally, the design prin-
ciple is to maintain a temperature of 20 - 25°C. Each country has its own fire protection legislation
and practices. Fire protection design must, therefore,
always be reviewed with local authorities. In addition,
the insurance companies may require a certain fire
9.7.3 Air filtering and silenc- protection level, or may offer reduced fees for plants
ers with a high protection level.

Air filtering
Air filtering is needed to prevent dust particles from
9.8.2 Fire areas
entering the building. The air filters for engine hall In order to limit the spread of fire, protect personnel
process ventilation should be equipped with local and limit the consequential damages in case of a fire,
differential pressure meters, optionally with remote the power plant should be subdivided into separate
supervision in the plant control system. fire areas. Different fire areas should be separated
The filters used by Wärtsilä are changeable bag filters with fire barriers, spatial separation or other approved
with filter media made of fibre. Standard filtration means.
class is Eurovent 779 G4 or ASHRAE 52.2 MERV 8 Fire barriers are typically used to separate the rooms
for the process ventilation and F5 or MERV 10 for or oil filled transformers. Spatial separation is used
the comfort ventilation. On locations with high con- between buildings, tank areas, fire pump station and
centrations of dust in the outside air, various types of also transformers if there is space available.
pre-filtration systems are used.

Silencers
Project specific noise calculations give the allowable
noise emission to the surroundings from the ventila-
tion system. As a rough assumption, total allowed
sound level for all ventilation units can be regarded to
be 65 dB(A) at 100 m distance.

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9.8.3 Fire alarm system Fire alarm cables

The system supplier’s recommendations should be
General followed. In addition, locally valid standards, rules
The purpose of the fire alarm system is to give people and regulations must be followed. Local fire regula-
in the building enough time to escape in case of a tions may, for instance, require the use of fire resis-
fire, and to start the fire extinction as early as possi- tant cables. Unless EMT conduits are required, Wärt-
ble. Fire detectors and alarm devices must be installed silä uses aluminium tubes around indoor cables not
throughout the plant. In hazardous areas, Ex or running on cable ladders.
ATEX classified equipment must be used.
The plant control system can be programmed to initi- 9.8.4 Gas detection system
ate a plant shut down on a specific fire alarm.
Gas detectors are required in the engine hall to detect
Fire alarm centre any gas leak. The detectors, at least two per engine,
should be located where gas most likely will be pre-
The fire alarm centre should be centrally located, sent in case of a leakage, which is, normally above the
preferably in the control room. The alarm centre compact gas ramps and at the ventilation air outlets at
must be equipped with a DC system as reserve power roof level.
supply.

Fire detectors and manual call points

The engine hall should be provided with optical
smoke detectors, differential heat detectors or flame
detectors. In other rooms, heat detectors or ionisa-
tion smoke detectors can be used. The number of
detectors depends on their coverage area or allowed
spacing, the size, shape and height of the rooms, the
ventilation, and the air change rate. To avoid false
alarms, the intended use of the room must be consid-
ered when designing the fire detection system.
Figure 122. Gas detectors
Manual call points should be provided at critical
points and exit points.
The gas detection system should be connected to the
plant control system, which activates an alarm when a
Fire alarm signalling devices gas detector is sensing 10 % of the lower explosion
Alarm devices should be placed so that they can be limit (LEL). When a gas detector is sensing 20 % of
seen or heard in all locations where people stay more LEL or more, the gas supply is shut off. If the gas
than temporarily. Alarm lights are obligatory inside detectors have only one alarm level, 20 % of LEL is
the engine hall where the sound level is high. Outside used for initiating shut-off of the gas supply.
the buildings, sound alarm can be used.

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9.8.5 Fire extinguishing sys- If fire brigade services are available, there should be
at least one fire department connection to allow for
tems additional water supply.
General Fire water tank and pumps
Water-based, gas-based, or foam fire extinguishing A fire water tank and fire fighting pumps are required
systems can be used. Gas-based systems may be used if the regular water supply system cannot be relied
in relatively small enclosed spaces like electrical upon to supply water for the required flow and pres-
rooms. Water or foam systems can also be used in an sure.
optional sprinkler system in the engine hall.
According to the Wärtsilä base level system design,
A water-based fire fighting system consists of: the water capacity of the fire water tank is at least 240
m3 and according to the extended level systems, at
· A water supply source, possibly a fire water tank least 600 m3. For filling the tank, raw water must be
and pumps
available, and possibly one or more pumps. Accord-
· A fire water piping system, fire hydrants, loose fire ing to NFPA22, the tank should be filled within eight
hose equipment, permanently connected fire hose hours, and according to European regulations longer
reels, and mobile foam units filling time is accepted.

· Possibly an automatic sprinkler system Typically there are two fire fighting pumps of ade-
quate capacity, one electric and one diesel engine
· Portable extinguishers. driven, either one able to deliver the required amount
of water. The pumps should be located near the fire
Primarily, a burning gas flame should be extinguished water tank and so that they are not exposed to fire in
by shutting off the gas flow. Otherwise, remaining the surrounding areas.
unburned gas may ignite on contact with hot sur-
faces. A sprinkler system cools the hot surfaces and Wärtsilä can provide a standard fire fighting pump
so reduces the risk for re-ignition. container including a control system. The container
has two fire fighting pumps, one diesel driven and
Fire fighting water supply requirements one electrically driven, and a jockey pump that main-
tains the system pressure in the pipes. The fire fight-
The fire fighting water source should supply the fire ing pumps are started automatically when the pres-
hydrants, hoses and sprinklers with adequate amount sure drops below a certain limit. The diesel pump
of water. Unless local regulations impose stricter re- serves as a back-up pump and has a lower starting
quirements, the system should be sized for two hours pressure than the electrical main pump.
of operation for both hydrant and sprinkler systems
in accordance with NFPA 850-4-2.1. Fire water pipes, hydrant posts, hoses and
Minimum requirement for hose streams according to mobile foam units
NFPA 850 is 1900 l/min. The flow required for the
The fire service piping conducting water to the hy-
sprinkler system calculated according to NFPA 13
drants, is a closed loop system consisting of pipes,
Area/density method, is about 3000 l/minute (for
valves, elbows, branches, reducers and shut-off
one engine hall). As both should be able to operate
valves. To ensure adequate pressure at the outlet
simultaneously, required minimum flow is about 5000
points, the pressure drop in the system must be cal-
l/minute.
culated and checked.
At the rated flow, the fire pump pressure must be at
Generally, Wärtsilä uses standpipes of class II in ac-
least 8 bar, but not exceeding the design pressure of
cordance with NFPA 14. The main pipe from the fire
the pipe system at zero flow, max. 12 bar. The shut
water source is built with NFPA24 as guideline (pri-
off head shall not exceed 140% of the rated head.
vate fire service main).

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Hydrant posts and hose reels shall be located in ac- The water should fulfil the highest requirements for
cordance with locally valid regulations but mainly any process in the plant. Possible seasonal changes in
keeping in mind the practicality. the raw water quality must be considered.
Mobile foam units are used to suppress possible oil The following scheme gives an overview of the water
fires. supply system in a plant with water treatment.

Automatic sprinkler system

Wärtsilä’s extended level fire fighting system includes
a wet type sprinkler system. The system is heat acti-
vated – sprinklers in the fire area are activated by the
heat – and equipped with a flow activated alarm. To
avoid accidental release, temperature class high is
used (93-141°C). The ordinary temperature rated,
closed head sprinklers shall not be used in the engine
hall.
When designing a sprinkler system, note that the pipe
support structures must be substantial enough to
carry the piping system filled with water.
The sprinkler system must be supplied directly from
Figure 123. Water treatment and storage
the fire service main pipe or alternatively from the
engine room stand pipe system provided that the size
of the piping is increased and hydraulically calculated Even though no water treatment is needed, a pure
for adequate water supply capacity. water tank and booster pumps may be needed for
peak consumption.
Portable extinguishers
The water booster is designed for a water pressure of
Carbon dioxide extinguishers are used in electrical at least 4 bar. Water boosters are needed if this water
spaces and in the control room. Powder extinguishers pressure is not otherwise obtained. For a pure single
are used in the engine hall, auxiliary hall, workshop cycle gas plant this is not critical due to the small
and other areas. number of consumers.

9.9.2 Water consumption

9.9 Water supply system Process water is consumed by the following proc-
esses:

9.9.1 General · Make up water in the primary cooling water sys-

tem.
The water used in the plant can be taken from a mu-
nicipal water supply system or ground water well if · Heat recovery system (if included)
reliable supply of sufficient quality, amount and pres-
sure is available. In areas where this is not the case, a In addition, water is needed for the fire fighting sys-
water tank and possibly a water treatment unit may tem, washing, and for sanitary water in toilets and
be needed. The need for water treatment depends on personnel rooms. In a gas plant with radiator cooling,
the raw water quality, which must be investigated by a the largest water consumer is the sanitary system.
raw water analysis.

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Wärtsilä 50SG Power Plant Product Guide 9. SITE, CIVIL WORKS AND STRUCTURES

In a plant without heat recovery, the water supply 9.9.5 Water storage tanks
system should be sized for a consumption of 3 li-
tres/MWhe. The recommended water treatment ca- The pure water tank should be sized to allow for 8
pacity for the heat recovery is minimum 10 % of the hours’ stop in the water supply. Likewise, in a plant
steam production when there is full condensate re- with water treatment, the recommended volume of
turn (boiler feed water quality). the raw water tank is 10 hours’ raw water demand or
minimum 10 m3.
If water treatment is employed, the average raw water
consumption will be higher due to water rejected The treated water tanks can be fibreglass, plastic or
from the treatment process. Typically, there should stainless steel tanks, or carbon steel tanks with im-
be raw water available 1.7 times the pure water con- mersion proof epoxy paint inside.
sumption as an average.

9.9.3 Water treatment unit 9.10 Waste water systems

Water can be treated in several different stages de-
pending on the purpose of the water. If a higher level
of cleanness is required, e.g. softening, reverse osmo- 9.10.1 Sewage system
sis and disinfection can be utilised.
The sewage water comprises water from toilets,
Wärtsilä offers a standard water treatment plant washing basins, and washing water from drainage.
comprising filtration, softening, and Reverse Osmosis The amount of sewage water can be estimated to be
(demineralisation). The plant is available in four sizes: the same as the sanitary water consumption.
1, 2, 4 and 6 m3/h. A treatment plant with a capacity
larger than the calculated demand should be chosen, If local laws and regulations so require, the sewage
including a safety margin of at least 20%. water must be treated before discharged to the mu-
nicipal water treatment plant or nature. The sewage
For big power plants two smaller water treatment water treatment should be chosen based on the local
plants may be considered instead of one big system. outlet water requirements.
Using two plants (2 x 50%) provides some level of
redundancy to ensure water supply for critical process
equipment. 9.10.2 Oily water collection
For quality requirements, see section 12.3. system
General
9.9.4 Water booster unit Oil contaminated water from the floor drains in the
engine hall, workshop, tank yard and unloading pump
In a power plant there are several small water con-
station should be collected by gravity to oily water
sumptions that require water only for short periods.
collecting sumps, generally concrete tanks situated
On the other hand, the pipe connections can be rela-
below ground. See Figure 116. From the collecting
tively long and tortuous. This exposes pumps to ex-
sumps oily water is pumped to the oily water tank,
cessive wearing and pressure strokes. In order to pro-
where it is stored until transportation for disposal or
tect the pump from ageing too fast, pressure balanc-
treatment.
ing water tanks can be installed close to the consump-
tion points. A pressure balancing tank is basically a
small tank, about 100 … 120 l (26 … 32 gallons) with Oily water sumps
a certain water level that is divided by a diaphragm. Oily water sumps are available in three standard sizes:
The pre set pressure (with air) shall be close to water 2.5 m3, 5 m3 and 10m3.
booster starting pressure.

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Wärtsilä 50SG Power Plant Product Guide 9. SITE, CIVIL WORKS AND STRUCTURES

9.11 Lighting

General
The requirements set by local laws and regulations
must be followed. If needed, all equipment on the
site, indoors and outdoors, should be illuminated.

Figure 124. Oily water sump

The sumps are equipped with upper and lower level

switches for automatic control of the transfer pumps.
The needed number of sumps depends on the plant
size and layout.
Figure 125. Site lighting example
Oily water transfer pump unit
Lighting levels
The standard oily water pump unit for transferring
sludge from the sludge sumps to the oily water tank is As standard Wärtsilä uses the following lighting lev-
an air-driven diaphragm pump mounted on a frame. els:
The typical pump unit has a nominal capacity of 6
m3/h depending on the pressure loss in the pipeline. Engine hall: 300 lux
Control rooms: 500 lux
The transfer pump unit can be configured for manual
or automatic operation. In automatic operation it is Office: 500 lux
equipped with a control panel Switchgear room: 200 lux
Workshop: 300 lux
Oily water unloading pump unit Store: 200 lux
Electrical rooms: 200 lux
The oily water unloading pump unit for pumping oily
water from the oily water tank to a truck is similar to Outdoors: 20 lux
the oily water transfer pump unit described above. Other rooms 200 lux
The pump is started and stopped manually. Table 32. Lighting levels

Oily water tank

Emergency exit lighting
The standard oily water tank delivered by Wärtsilä is a
vertical cylindrical tank made of carbon steel, which is Emergency lights should be installed above all exit
placed above ground. To prevent freezing in cold doors clearly visible inside the building
climates, the oily water tank should be equipped with
a heating coil.

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Emergency lighting Aviation obstruction lighting

Lighting provided for a safe illuminated route out of If local regulations so require, the stacks must be
the building when the supply to the normal lighting equipped with obstruction lights to make them visible
fails for aviation.

Ex-areas
In hazardous areas, lighting shall be ex-classified.

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Wärtsilä 50SG Power Plant Product Guide 10. INSTALLATION AND COMMISSIONING

10. INSTALLATION AND COMMISSIONING

Jacking
10.1 Delivery and storage The engine and the generator can be lifted using hy-
draulic jacks placed in the jacking points, three on
each side for the engine part, and two for the genera-
10.1.1 Engine generator set tor part.

Transportation
The engines are transported on the engine base
frame, and the generators are transported on the gen-
erator base frame. The engine and generator are cov-
ered by a tarpaulin during delivery and transportation.

Storage
Figure 127. Lifting engine generator set by jacking
It is recommended to store the engines and genera-
tors indoors. If stored outdoors, the original covering
must be kept unbroken. 10.1.2 Engine auxiliary
equipment and pipes
Lifting the engine
The auxiliary modules and units are delivered in con-
If needed, the engine can be lifted with a crane. Lift-
tainers or boxes. It is recommended to store them
ing plates and shafts are mounted at the factory on
indoors. If stored outdoors, they should be kept un-
their proper places.
packed or covered with a tarpaulin. Pipes must be
stored indoors in dry and warm conditions.

10.1.3 Electrical and control

system equipment
The electrical equipment should be stored indoors in
dry and warm conditions according to the manufac-
turer’s instructions. In cold climates, also the cables
need to be stored in a warm location for 24 hours
before installation.
The equipment must be lifted in accordance with the
manufacturer’s instructions.

Figure 126. Lifting the engine with a crane

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Wärtsilä 50SG Power Plant Product Guide 10. INSTALLATION AND COMMISSIONING

10.2 Installation 10.2.2 Installation of engine

generator set

10.2.1 General Moving the engine generator set to its posi-

tion
The installation of the engine generator sets and the
auxiliary equipment must be done in accordance with The engine and generator with base frames are hauled
the drawings and installation instructions provided to their position in the engine hall separately, and
for the specific project in the installation file. Before positioned on the concrete foundation.
starting the installation work, all necessary documents
are given to the client and to the subcontractors at Positioning and aligning generator set
site.
The engine and generator are lifted with hydraulic
The site manager and his supervisors follow up that jacks, and joined with fastening screws. The generat-
the quality instructions, installation instructions and ing set must be installed exactly in accordance with
contract requirements are followed at site. the installation drawings.
The mechanical installation involves the following The vibration mounts must be fixed to the base
main work phases (not necessarily in this order): frames in exact positions in accordance with the
drawings.
· Installation of the engines and generators
Maximum allowed deviation in floor level between
· Installation of the standard modules and other each spring package and within each package area
auxiliary units must not be exceeded
· Pipe installation and flushing For aligning the generator set horizontally shim
plates are to be used to compensate for allowed level
· Installation of maintenance platforms deviations between spring packages.
The installation of the electrical systems and control When the engine and generator are joined, the cou-
systems involves lifting and placing switchgear, con- pling can be aligned.
trol cabinets, transformers, etc., cable pulling, and
connecting the cables.
To enable the installation of the engine and genera-
tor, a sufficient large opening should be left in the
wall at the generator side. Alternatively, the entire
wall may be left open until the engine generator sets
have been installed.
If there is restricted space in the auxiliary area, it may
be most practical, or even necessary, to place the en-
gine auxiliary modules and exhaust gas modules in
their approximate positions before installing the en-
gine generator sets. However, the modules cannot be
aligned and mounted until the engine is attached to
the generator, and placed in its final position.
Figure 128. Spring elements

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Wärtsilä 50SG Power Plant Product Guide 10. INSTALLATION AND COMMISSIONING

Anchorage to foundation 10.2.4 Installation of piping

The engine generator sets are mounted on anti- systems
vibration mounts and do not need an anchorage onto
the foundation, except in earthquake sensitive areas. Installation procedure
In earthquake sensitive areas, the anchorage for per-
manent equipment shall be designed to resist the lat- The following aspects shall be taken into considera-
eral seismic forces prescribed in national standards. tion when planning the installation:
The lateral anchorage to the concrete foundation
· Install all units and major equipment before start-
must be arranged with chemical anchor bolts. De-
ing to install the pipes
tailed design drawings shall be provided.
· Install larger pipes prior to smaller ones and main
lines before branches
10.2.3 Installation of auxiliary
· Technically more difficult systems should be built
equipment before simpler systems
Engine auxiliary modules Pressure Tests of piping systems
The engine auxiliary module must be exactly aligned All piping systems must be pressure tested after they
with the engine and is therefore installed after the are welded and before final pickling or flushing and
engine, although it may be necessary to place it cleaning.
roughly in its position before the engine is installed.
The module is mounted to the floor with bolts, and Wartsila requires the pipe test pressure to be 1.43 x
the feet are welded to the module frame after the the pipe design pressure. Test records or each pres-
module is finally aligned in its position. Pipes be- sure tested pipe to be made and kept in the quality
tween the auxiliary modules and the engine are con- records maintained by the contractor who is respon-
nected by flexible bellows, which have to be installed sible for the pressure test execution.
carefully according to design drawings to maintain
permissible compression of each bellow. See further Cleaning procedures
details in section 10.2.4.
All pipes must be inspected and ensured to be clean
Exhaust gas module from debris before installation and joining. Espe-
cially, all fuel gas and lubricating oil pipes must be
Like the engine auxiliary modules, the exhaust gas well cleaned to ensure that no sand, rust, slag, etc. will
modules should be lifted on their stands before the enter the engine.
engine generator sets are brought to their places. The
exhaust gas modules are lifted on to the stands with a
crane or fork-lift truck. Exhaust gas bellows have to
be installed between the engine and the exhaust gas
module as per design drawings.

Other auxiliary units

Generally, standard auxiliary units are skid mounted
for easy installation. Mechanical and electrical installa-
tion of these units has to be made by qualified instal-
lation contractor following detailed design drawings.

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Wärtsilä 50SG Power Plant Product Guide 10. INSTALLATION AND COMMISSIONING

The following cleaning methods should be used: · The installation length must be correct.
Pipe A B C D E F H · Minimum bending radius must be respected.
Fuel gas pipes x x x · Piping must be concentrically aligned.
Lube oil pipes x x x x
Compressed air pipes x x x
· Mating flanges shall be clean from rust, burrs and
anticorrosion coatings.
Cooling water pipes x x x x
District heating pipes x x x · Flexible elements must not be painted.
Steam pipes x x x
· The piping must be rigidly supported close to the
Exhaust gas pipes x x flexible piping connections.
Charge air pipes x x x x

where: 10.2.5 Installation of electrical

A= Degreasing by washing with alkaline solution in hot wa- and control systems
ter at 80 °C (if the pipe has been greased)
B= Removal of slag, rust and scale with steel brush (not General
required for seamless precision tubes)
C= Purging with compressed air The installation of the electrical and control systems
D= Pickling must be done by authorized electricians.
E= Sand blasting or shot blasting The installation of boards, panels and cabinets can be
F= Flushing with lube oil started when the installation site is dry, painted and
H= Flushing with water finished. The cabling can be done when the equip-
ment has been installed and the conduits and cable
The pipes included in the standard modules are ladders are in place. Cable racks are generally installed
cleaned and flushed in the shop. If a pipe inspection after the process piping and ventilation ducts to en-
at site shows that no dirt or rust has been formed in sure future accessibility.
the pipes during transportation and storage, a final
flushing of the lube oil pipes of delivered modules is The electrical contractor should supervise the con-
enough. struction of elevated floors, cable trenches, and open-
ings to ensure trouble free installation of the electrical
All piping systems built on site must be pressure equipment, and to ensure that trays and racks are
tested, cleaned and flushed before they are connected lifted in before the routes are blocked.
to any Wartsila supplied module, unit or engine. Pipe
welding, pressure testing and cleaning/flushing re- Installation of equipment
cords to be maintained by mechanical contractor re-
sponsible for such works. The results of such tests to Electrical equipment, such as switchgear, transform-
be kept for Wartsila supervisors/advisors inspection. ers, control cabinets, neutral point cubicles, and DC
cabinets are assembled, mounted and fixed in accor-
Installation of flexible pipe connections dance with the manufacturer’s instructions, the elec-
trical drawings and the layout drawings.
Great care must be taken to ensure the proper instal-
lation of flexible pipe connections between resiliently Before installing the LV and MV switchgear, the po-
mounted engines and fixed piping. The flexible bel- sitions and dimensions of the foundations and cable
lows and hoses included in the engine delivery must openings must be verified. During the MV switchgear
be used. installation, the arc discharge channels must be re-
garded.
Note, for instance, the following:

· Flexible pipes must not be twisted.

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Wärtsilä 50SG Power Plant Product Guide 10. INSTALLATION AND COMMISSIONING

Installation of electrical cables 10.3.2 Pre-commissioning

When installing the cables, cooperation with the me- Pre-commissioning covers all the mechanical and
chanical installation personnel is required in order to electrical inspections and tests required to prepare the
avoid encounters with piping or other structures. plant before the plant is energized.
Borings for small penetrations through the walls are
carried out by the installer. Larger openings are re- Pre-commissioning involves, for instance:
served in the construction drawings.
· Pressure tests, cleaning and flushing of piping sys-
Cable pulling must be done in controlled circum- tem as per procedure specific for each auxiliary
stances, and not in too low ambient temperatures, system
according to the manufacturer’s instructions. To re-
duce friction, the cables should be lubricated with · Installation inspections of all mechanical units and
appropriate grease. modules

All cables connected to the engine generator set must · Installation inspection of all electrical modules
be cut, laid and fastened with slack so as to allow the and panels
movements of the engine generator set without caus-
· Inspection of earthing system connections for
ing stress on cables and terminals.
each electrical consumer
Marking of cables · Installation inspections of all cable trays and ducts
The cables must be marked in both ends with the · Continuity and insulation resistance tests of all
identification number in accordance with the cable pulled cables
lists. Each cable core is marked with the codes of the
terminals to which it is connected. · Functional tests of protection relays
· Loop tests of control circuits – from field equip-
ment to control panels

10.3 Commissioning · Interface tests between external system and Wärt-

silä equipment
· Insulation resistance or high voltage dielectric
10.3.1 General tests of generators windings and MV power ca-
bles.
The term “commissioning” means the activities nec-
essary to bring the power plant into operation after The tests must be done in accordance with applicable
the installation. It can be divided into the following standards.
phases:
Pre-commissioning involves also the inspections and
· Pre-commissioning before first start-up of the tests related to civil works, such as buildings,
engine generator sets grounds, heating, ventilation, proper illumination and
lightning protection etc. These activities start already
· First start-up, running in and fine tuning during the construction phase and continue through
the installation phase. Their scope depends on the
· Performance tests actual scope of supply defined in the contract.
Part of the activities can be performed simultane- When the plant electrical systems are energized for
ously; part of them must be performed sequentially. the first time, the power is usually supplied by an ex-
ternal source, normally back-fed from the grid. When
energizing equipment, the correct voltage and phase
rotation must be checked and verified.

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Wärtsilä 50SG Power Plant Product Guide 10. INSTALLATION AND COMMISSIONING

10.3.3 Running in and fine Performance tests are conducted to demonstrate and
verify compliance with the performance guarantees in
tuning the contract. The test parameters, guaranteed per-
formance values, and the performance tests proce-
Engine generator sets dures are project-specific and specified in the con-
First start-up and running in of a new engine must be tract. Project specific derating curves shall be in-
performed according to the program provided for the cluded in the contract, these will define how the en-
engine. Functional tests must be done and recorded. gine will react and perform in actual site conditions.
The actual site conditions may differ from standard
Required adjustments of the engine generator sets reference conditions for which guaranteed perform-
and compact gas ramps should be done by qualified ance values are given.
personnel from Wärtsilä.
The tests may include the following performance pa-
rameters:
Auxiliary systems
Before starting the auxiliary systems, they must be · Power output, from individual engine generator
filled. During first start-up, they are verified for cor- sets and/or from entire plant
rect function. The commissioning staff should fine · Heat rate
tune and record the process values. Fine tuning re-
quired on the auxiliary systems at site involves: · Lube oil consumption
· Cooling system flow adjustments · Power consumption of plant auxiliaries
· Adjustment of suction/discharge pressures of · Voltage and frequency variations
lube oil system pumps
· Noise emissions
· Adjustment of gas supply system
· Stack emissions.
· Adjustments of all the auxiliary systems as neces-
sary for correct operation of the plant. The scope The performance test results are documented in a
of adjustments depends on actual design, used commissioning file. A handing over certificate shall
equipment and limits of contractual scope of sup- be issued by Wärtsilä after a successful execution of
ply. the performance tests.
Any open items will be listed in a punch list, and a
schedule for corrective actions is made. Such a punch
10.3.4 Performance tests list, if applicable, shall be added to the hand over cer-
tificate.
General
Performance tests can be done when the installation
is completed, and all pipe systems, auxiliary units,
electrical systems, and control equipment are adjusted
for correct operation.

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Wärtsilä 50SG Power Plant Product Guide 11. TECHNICAL DATA

11. TECHNICAL DATA

11.1 Engine generator set

The following data is based on 100% load (power factor = 0.8), standard reference conditions according to ISO
30464 and defined at generator terminals.

Engine type Wärtsilä 18V50SG

Compression ratio Hz 11:1
Frequency Hz 50 60
Electrical power kW 18321 18759
NOx setting mg/Nm³ 250 500 250 500
Electrical heat rate kJ/kWh 7571 7411 7571 7411
Electrical efficiency % 47,6 48,6 47,6 48,6
Table 33. Electrical Output and -heat rate

Including engine driven pumps, heat rate and efficiency includes 5% tolerance according to ISO 3046-1

4 Except for charge air coolant temperature, which is 35 °C

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Wärtsilä 50SG Power Plant Product Guide 11. TECHNICAL DATA

11.2 Engine Technical data

Engine type Wärtsilä 18V50SG

Engine speed rpm 500 514
Frequency Hz 50 60

Fuel gas system

Pressure before engine, typical kPa (bar) 450 (4,5)
Gas inlet temperature °C 0 - 60

Lubricating oil system

Specific consumption, max g/kWh 0,5
Pressure before bearings, nominal kpa (bar) 400 (4,0)
Pressure before bearings, alarm kpa (bar) 300 (3,0)
Pressure before bearings, stop kpa (bar) 200 (2,0)
Oil volume, wet sump (nom) m³ 12,5
Pump capacity, main engine driven m³/h 345 335
Pump capacity, priming m³/h 100

Starting air system

Pressure before engine, nominal maximum Mpa (bar) 3 (30)
Pressure before engine, minimum for successful start Mpa (bar) 1,5 (15)
Low pressure limit in air vessel Mpa (bar) 1,8 (18)
Air consumption per start attempt, average at 20°C5 Nm³ 20

Engine control air system

Consumption (Load dependent) Nm³/min 0,5

Cooling water system

Pump capacities (LT & HT), nominal flow m³/h 400
HT water volume m³ 2,6
HT temp after engine, nom.1-C /2-C system °C 91
Pressure drop over engine, LT charge air cooler kPa (bar) 30 (0,3)
Pressure drop over engine, LT lube oil cooler kPa (bar) 60 (0,6)
Pressure drop over engine, HT kPa (bar) 70 (0,7)
Table 34. Technical data

5 Including slow turn sequence

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Wärtsilä 50SG Power Plant Product Guide 11. TECHNICAL DATA

11.3 Engine heat balances

The heat balances are based on standard reference conditions as defined in ISO3046-1, except for charge air
coolant temperature which is 35°C. Output, BSEC and efficiency are declared at the flywheel.
The following tolerances will apply: BSEC and efficiency 5% (ISO 3046-1), flows ± 5%, Exhaust gas tempera-
ture ± 15°C, Charge air temperature after compressor ± 5%, Heat loads ± 10%, Radiation ± 20%.

Load % 100 90 75 50 30

Rated output kW 18810

Brake mean effective pressure, BMEP kPa 2200 2000 1650 1100 660
Brake specific energy consumption, BSEC kJ/kWh 7218 7342 7535 7886 8705
Efficiency % 49,88 49,04 47,78 45,65 41,36
Engine output kW 18810 16929 14108 9405 5643
Lube oil kW 1422 1387 1353 1261 1201
Jacket water kW 1859 1762 1637 1369 1280
Air temp. after comp. °C 215 202 179 133 102
Charge air HT kW 4539 3873 2913 1409 639
Charge air LT kW 803 621 408 158 70
Charge air total kW 5342 4494 3321 1567 709
Charge air flow kg/s 29,9 27,0 23,0 15,8 10,5
Radiation kW 540 510 510 510 510
Exhaust gas flow after TC kg/s 30,7 27,7 23,6 16,3 10,8
Exhaust gas temp after TC °C 375 388 409 438 450
Table 35. W18V50SG, 50 Hz, NOx = 500 mg/Nm³, CR=11:1

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Wärtsilä 50SG Power Plant Product Guide 11. TECHNICAL DATA

Load % 100 90 75 50 30

Rated output kW 19260

Brake mean effective pressure, BMEP kPa 2200 2000 1650 1100 660
Brake specific energy consumption, BSEC kJ/kWh 7218 7342 7535 7886 8705
Efficiency % 49,88 49,04 47,78 45,65 41,36
Engine output kW 19260 17334 14445 9630 5778
Lube oil kW 1423 1387 1353 1261 1201
Jacket water kW 1860 1763 1638 1369 1280
Air temp. after comp. °C 215 202 179 133 102
Charge air HT kW 4625 3948 2972 1439 653
Charge air LT kW 840 651 427 165 72
Charge air total kW 5465 4599 3399 1604 725
Charge air flow kg/s 30,6 27,6 23,5 16,2 10,7
Radiation kW 540 510 510 510 510
Exhaust gas flow after TC kg/s 31,4 28,4 24,2 16,7 11,0
Exhaust gas temp after TC °C 375 388 408 438 450
Table 36. W18V50SG, 60 Hz, NOx = 500 mg/Nm³, CR=11:1

11.4 Generator data (typical)

Engine Wärtsilä 18V50SG

Frequency 50Hz 60Hz

Rated output KVA 22900 23448
Power factor cos phi 0,8 0,8
Rated voltage V 11000 15000 13800
Rated current A 1202 881 981
Insul.class/Temp.rise F/F F/F
r.p.m. 500 514
Enclosure IP23 IP23
Standard IEC60034
Ambient C° 50 50
Altitude m 1000 1000
Table 37. Technical data for medium voltage generators

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Wärtsilä 50SG Power Plant Product Guide 12. FLUID REQUIREMENTS

12. FLUID REQUIREMENTS

12.1 Fuel gas requirements

The Wärtsilä 50SG engine is designed to operate In addition, to ensure the long term performance of
without de-rating on natural gas qualities according the emission control system (if included), the con-
to the following specification. centrations of sulphur components and catalyst poi-
sons must be within the limits specified by the cata-
lyst supplier.

Quality Limit values Notes

Lower Heating Value (LHV) ≥ 30 MJ/Nm3 Lower Heating Value corresponds to the energy content of the gas.
If the LHV is too low, the engine output has to be reduced, or the
gas pressure to the engine must be raised.
Methane number (MN) ≥ 65 Dependent on engine optimisation and ambient conditions.
Methane content, CH4 ≥ 70 vol. %
Hydrogen sulphide, H2S 0.05 vol.% Hydrogen sulphide H2S may cause corrosion on the gas handling
equipment.
Hydrogen, H2 ≤ 3 vol. % Any higher hydrogen contents must be agreed upon case by case.
Water and hydrocarbon condensates Not allowed The dew point of natural gas is below the minimum operating
before the engine temperature and pressure.
Ammonia, NH3 ≤ 25 mg/Nm3
Chlorines + Fluorines ≤ 50 mg/Nm3
Particles or solids, content ≤ 50 mg/Nm3 At the engine inlet.
Particles or solids, size ≤ 5 μm Particles can be the reason for improper sealing and function of
the gas handling equipment.
Gas inlet temperature 0 – 60 °C
Table 38. Fuel gas quality requirements

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Wärtsilä 50SG Power Plant Product Guide 12. FLUID REQUIREMENTS

The Methane Number provides a scale for evaluat- Viscosity class SAE 40
ing the knock resistance of the fuel gas. Methane Viscosity index (VI) Minimum 95
number (MN) indicates the percentage by volume of Alkalinity (BN) 4 - 7 mg KOH/g
methane in blend with hydrogen that exactly matches
Sulphated ash level Maximum 0.6 weight %
the knock intensity of the gas mixture in question
Too high ash content can cause pre-
under specified operating conditions in a knock test- ignition, knocking and spark plug
ing engine. A higher methane number means better fouling, while too low ash content
knock resistance. If the components of the fuel gas can lead to increased valve wear.
are known, the methane number can be calculated. Foaming characteris- Sequence I (24oC): 100/0 ml,
Heavier hydrocarbons as ethane, propane and butane tics according to the Sequence II (93.5oC): 100/0 ml,
will lower the methane number. Carbon dioxide and ASTMD 892-92 test Sequence III (24oC): 100/0 ml
nitrogen will increase the methane number. method (fresh lube oil)
Table 39. Lube oil requirements

12.2 Lubricating oils 12.2.2 Additives

The oils should contain additives that give good oxi-
dation stability, corrosion protection, load carrying
12.2.1 General requirements capacity, neutralization of acid combustion and oxi-
dation residues, and should prevent deposit forma-
The lubricating oil should fill the following general tion on internal engine parts (piston cooling gallery,
requirements: piston ring zone and bearing surfaces in particular).

12.2.3 Approved lubricating

oils
Lubricating oils approved by Wärtsilä should be used.
See Table 40. The use of approved lubricating oils is
mandatory during the warranty period and is also
strongly recommended after the warranty period has
expired.

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Wärtsilä 50SG Power Plant Product Guide 12. FLUID REQUIREMENTS

Supplier Brand name Viscosity BN Sulphated ash

(w-%)
BP Energas NGL SAE 40 4.5 0.45
Castrol Duratec L SAE 40 4.5 0.45
Chevron (Texaco) Geotex LA SAE 40 5.2 0.45
HDAX 5200 Low ash SAE 40 4.2 0.50
ExxonMobil Pegasus 705 SAE 40 5.3 0.49
Pegasus 805 SAE 40 6.2 0.50
Pegasus 905 SAE 40 6.2 0.49
Pegasus 1 SAE 40 6.5 0.49
Pegasus 1005 SAE 40 5.0 0.50
Idemitsu Kosan Co. Ltd. Apolloil GHP 40L SAE 40 4.7 0.45
Petro-Canada Sentron 445 SAE 40 4.7 0.40
Shell Mysella LA 40 SAE 40 5.2 0.45
Mysella XL 40 SAE 40 4.5 0.50
Total Nateria X 405 SAE 40 5.2 0.45
Table 40. Approved lubricating oils

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Wärtsilä 50SG Power Plant Product Guide 12. FLUID REQUIREMENTS

12.3 Water quality requirements

Substance Unit Engine Urea Cooling Steam boiler Steam Steam boiler Hot water Oily
cooling, mix- tower make-up boiler feed water boiler water water
turbo ing (circula- (If high qual- (Preferred (p<15bar) (p<15 bar) treat-
charger and water tion wa- ity conden- make-up ment
separator (SCR) ter) sate return > quality)
washing 95%
water
General appearance Visually clear and colourless. No smell.
pH at 25 °C > 6,5 >6 6.5 to 8 9 to 9.5 9,5 to 11 9 to 10 6 to 8
Conductivity at 25 mS/m <100 < 20 < 80 < 20 < 500
°C
TDS mg/l <110 <1500 < 450 < 110 < 2600
Total Hardness TH °dH < 10 < 0.1 4.5 - 456 < 0.2 < 0.1 <0.2
Alkalinity HCO3 mg/l < 300 < 80 < 20 < 500 <60
p - alkalinity mval/l 5 - 15
Oxygen O2 mg/l < 0,005 <0.02
Iron Fe and Cop- mg/l <0,1 Fe <3 <0.1 <0,1 Fe <0.1 < 0,5
per Cu Cu <1 Cu <0.02
Silica SiO2 mg/l < 50 <5 < 150 < 15 <5 < 1007
Organics (KMnO4 mg/l (< 30) (< 10) < 3008 < 15
value)
Oil mg/l ND < 19 ND <1 <1 <1
Chlorides Cl mg/l < 80 < 10 < 450 10 < 40 < 10 < 200 <50 < 100
Phosphates mg/l 11(6) 20 – 40
Sulphates SO4 mg/l < 150 < 750
Sodium + Potas- mg/l <40 < 160 < 40 < 800
sium Na+K
Suspended solids mg/l < 10 <2 < 25 <5 <2 <10 < 10
Table 41. Water quality requirements

6 Maximum hardness in the cooling tower circuit water without chemical scaling inhibitors. Actual value depends on other
substances. LSI shall be close to zero
7 Maximum silicate content in the boiler is pressure dependent.
8Organic matter in the boiler water may lead to water bursting with steam, resulting in bad condensate quality
9 Oily and greasy substances are problematic with suspended oils
10 The chloride content can vary from 100 to 900 mg/l depending on construction. Note that the limit for the stainless steel

plate heat exchanger is only 300 mg/l.

11 Phosphates are added to the boiler feed water for binding hardness of the water. It will also raise the pH value slightly.

The final adjustment of pH is done by sodium hydroxide to maintain the p-value. The activated sodium sulphite or other
oxygen binding chemicals are also dosed to the boiler feed water

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Wärtsilä 50SG Power Plant Product Guide 13. DIMENSIONS AND WEIGHTS

13. DIMENSIONS AND WEIGHTS

13.1 Engine generator set

Figure 129. W18V50SG Generating set

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Wärtsilä 50SG Power Plant Product Guide 13. DIMENSIONS AND WEIGHTS

13.2 Standard auxiliary equipment

13.2.1 Compact gas ramp

Dimension / Pipe DIN design

Weight (gross) 654 kg
Fuel gas inlet DN100
Fuel gas outlet, main DN100
Fuel gas outlet, prechamber DN25
Venting 1 DN25
Venting 2 Ø15
Control air Ø12
Inert gas EO 12
Figure 130. Compact gas ramp

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Wärtsilä 50SG Power Plant Product Guide 13. DIMENSIONS AND WEIGHTS

13.2.1 Engine auxiliary module (EAM)

Figure 131. W18V50SG EAM module dimensions (example)

13.2.2 Exhaust gas module (EGM)

Figure 132. Wärtsilä 18V50SG Exhaust gas module dimensions

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Wärtsilä 50SG Power Plant Product Guide 13. DIMENSIONS AND WEIGHTS

13.2.3 Standard auxiliary units

Maintenance water tanks

Tank Pump flow A B C D E

volume 50 / 60 Hz
2.5 m3 5.4 / 6.5 m3/h 1206 mm 1500 mm 1209 mm 2000 mm 2527 mm
4 m3 5.4 / 6.5 m3/h 1206 mm 1800 mm 1509 mm 2500 mm 3027 mm
6 m3 9 / 10.8 m3/h 1636 mm 1800 mm 1509 mm 2500 mm 3027 mm
10 m3 9 / 10.8 m3/h 2036 mm 1800 mm 1509 mm 3400 mm 3927 mm
Figure 133. Dimensions of standard maintenance water tanks

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Wärtsilä 50SG Power Plant Product Guide 13. DIMENSIONS AND WEIGHTS

Exhaust gas silencers

Engine Type Attenuation Length Diameter Inlet c.l. height Weight

[dB (A)] [mm] [mm] [mm] (kg]
W18V50SG 35 12125 2800 1240 13395
Figure 134. Typical dimensions of an exhaust gas silencer

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Wärtsilä 50SG Power Plant Product Guide 13. DIMENSIONS AND WEIGHTS

Intake air filter (example)

Figure 135. Intake air filter dimensions for W18V50SG (example)

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Wärtsilä 50SG Power Plant Product Guide 13. DIMENSIONS AND WEIGHTS

Radiators (example)

L1
W1

Figure 136. Radiator field

Radiators /
Engine Fans / Radiator Engine Radiator field / engine L1 L W1 W
Type [Qty] [Qty] L x W [m] [mm] [mm] [mm] [mm]
W18V50SG 6 x 7,5 kW 4 11,6 x 10,7 1850 11550 2670 10680
Table 42. Typical dimensions of standard noise radiator field

Radiators /
Engine Fans / Radiator Engine Radiator field / engine L1 L W1 W
Type [Qty] [Qty] L x W [m] [mm] [mm] [mm] [mm]
W18V50SG 7 x 4 kW 4 12 x 10,7 1650 12000 2670 10680
Table 43. Typical dimensions of low-noise radiator field

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Wärtsilä 50SG Power Plant Product Guide PREFACE

APP A. STANDARDS AND CODES

General NFPA 37 Standard for the installation and use of

stationary combustion engines and gas
turbines
This appendix lists the most significant standards and
codes that Wärtsilä follows, where applicable, in the
manufacturing, design and engineering of Wärtsilä Fuel gas system
50SG power plants. NFPA 54 Fuel gas code
Explanation of abbreviations:
Standard auxiliary modules and units
API American Petroleum Institute
EN 292 Safety of machinery. Basic concept,
ASHRAE American Society of Heating, Refriger- general principles for design.
ating and Air-Conditioning Engineers
Piping systems
EN European standard
EN 13480 Metallic industrial piping.
IEC International Electrotechnical Commis- EN 1592-1 Flanges and Their Joints circular flanges
sion for pipes, valves, fittings and accesso-
ries.
ISO International Organization for Stan-
dardization Electrical and control systems
NFPA National Fire Protection Association IEC62271-200 A.C. Metal Enclosed Switchgear and
IEC60694 Control gear for Rated Voltages Above
OSHA Occupational Safety & Health Admini- 1 kV and Up to and Including 52 kV
stration IEC 60034 Generator
IEC 60076 Transformer
IEEE Institute of Electrical and Electronics EN 60439-1 Specification for low-voltage switchgear
Engineers and control gear assemblies. Type-
tested and partially tested assemblies.
Engine generator set IEC 60589 Lighting installation
IEC 34-1 Rotating electrical machines EN 54 IEC 60589 Fire detection
(EN 60034-1) IEEE 80 Earthing network
ISO 3046, 1 - 6 Specification for reciprocating internal IEC 60950 WOIS workstation hardware
combustion engines
IEC 60287 High voltage cable sizing
ISO 8178 Reciprocating internal combustion
engines. Exhaust gas emission meas- IEC60346/5-52 Low voltage cable sizing
urement. IEEE80 Grounding system
ISO 8528 Reciprocating internal combustion
engine driven alternating current gener- Fire protection
ating sets
EN 1834-1 Reciprocating internal combustion NFPA 10 Standard for portable fire extinguishers
engines. Safety requirements for design NFPA 13 Installation of sprinkler system
and construction of engines for use in NFPA 14 Standard for the installation of stand-
potentially explosive atmospheres.
pipe and hose system
EN 60204-1 Safety of machinery. Electrical equip-
NFPA 15 Water spray fixed systems for fire pro-
ment of machines. General require-
tection
ments.

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Wärtsilä 50SG Power Plant Product Guide PREFACE

NFPA 22 Standard for Water tanks for Private

FM Protection Platforms and staircases
NFPA 24 Standard for the Installation of Private
Fire Service Mains and Their Appurte- ISO 14122 Safety of machinery – permanent
nances means of access to machinery, part 1 –
4
NFPA 30 Flammable and combustible liquids
Code OSHA 1910 Occupational safety and health stan-
dard, sub part D – Walking-working
NFPA 37 Standard for the Installation and Use of surfaces
Stationary Combustion Engines and
Gas Turbines OSHA 1926 Safety and health regulations for con-
struction, subpart X - Stairways
NFPA 101 Life Safety Code
NFPA 850 Recommended practice for fire protec-
tion for electric generating plants and Ventilation and air conditioning
high voltage direct current converted ASHRAE 55 Thermal environmental conditions for
stations human occupancy
CEA 4001 Sprinkler System Planning and Installa- ASHRAE 62.1- Ventilation for Acceptable Indoor Air
tion
2004 quality
API 650 Tank Design Standard

Classification of hazardous areas

American codes
API 500 Recommended Practice for Classification of
Locations for Electrical Installations at Petro-
leum Facilities Classified as Class I, Division
1 and Division 2.
API 505 Recommended Practice for Classification of
Locations for Electrical Installations at Petro-
leum Facilities Classified as Class I, Zone 0,
Zone 1, and Zone 2
NFPA 30 Flammable and Combustible Liquids Code
European Codes
EN-60079- Electrical apparatus for explosive gas atmos-
10 pheres; part 10 Classification of hazardous
areas
EN-1834-1 Reciprocating internal combustion engines –
Safety requirements for design and construc-
tion of engines for use in potentially explo-
sive atmospheres – Part II engines for use in
flammable gas and vapour atmospheres.

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Wärtsilä 50SG Power Plant Product Guide

APP B. UNIT CONVERSIONS

Length units
Length m in Ft
m 1 39.370 3.2808
in 0.0254 1 0.083333
ft 0.3048 12 1
mile 1609.3 63360 5280
Table 44. Conversion table for length units

Length m In Ft
m 1 1/0.0254 1/(12*0.0254)
in 0.0254 1 1/12
ft 0.0254*12 12 1
mile 0.0254*63360 63360 5280
Table 45. Formulas for converting length units

Volume units
Volume cubic m l (litre) cubic foot Imperial US gallon
gallon
cubic m 1 1000 35.315 219.97 264.17
l (litre) 0.001 1 0.35315 0.21997 0.26417
cubic foot 0.028317 28.317 1 6.2288 7.4805
Imperial gallon 0.0045461 4.5461 0.16054 1 1.2009
US gallon 0.0037854 3.7854 0.13368 0.83267 1
Table 46. Conversion table for volume units

Volume cubic m l (litre) cubic foot Imperial gallon US gallon

cubic m 1 1000 1 / (12 * 0.0254)3 1/0.00454609 1/(231 * 0.02543)
l (litre) 0.001 1 1 / (12 * 0.254)3 1/4.54609 1 / (231 * 0.2543)
cubic foot (12 * 0.0254)3 (12 * 0.254)3 1 (12 * 0.254)3 / 123 / 231
4.54609
Imperial gallon 0.00454609 4.54609 4.54609 / 1 4.54609 /
(12*0.0254)3 (231*0.2543)
US gallon 231 * 0.02543 231 * 0.2543 231 / 123 231* 0.2543 / 1
4.54609
Table 47. Formulas for converting volume units

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Normal cubic meter (Nm3) – Standard cubic foot (SCF)

F
(60 °F, 14.7 psi (a)) = F 3 (0°C,101.325 kPa(a)) * 37,336
[SCF] Nm [ ]
F
(60 °F, 14.7 psi (a))
F
(0°C ,101.325 kPa(a) ) = [SCF]
[Nm 3 ] 37,336

Mass units
Mass kg lb Oz
kg 1 2.2046 35.274
lb 0.45359 1 16
oz 0.028350 0.0625 1
Table 48. Conversion table for mass units

Density units
Density kg / cubic m lb / US gallon lb / imperial gallon lb / cubic ft
kg / cubic m 1 0.0083454 0.010022 0.062428
lb / US gallon 119.83 1 0.83267 0.13368
lb / imperial gallon 99.776 1.2009 1 0.16054
lb / cubic ft 16.018 7.4805 6.2288 1
Table 49. Conversion table for density units

Energy units
Energy J BTU cal lbf ft
J 1 9.4781e-04 0.23885 0.73756
BTU 1055.06 1 252.00 778.17
cal 4.1868 3.9683e-03 1 0.32383
lbf ft 1.35582 1.2851e-03 3.0880 1
Table 50. Conversion table for energy units

Power units
Power W hp US hp
W 1 0.0013596 0.0013410
hp 735.499 1 1.0136
US hp 745.7 0.98659 1
Table 51. Conversion table for power units

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Pressure units
Pressure Pa bar mmWG Psi
Pa 1 0.00001 0.10197 0.00014504
bar 100000 1 10197 14.504
mmWG 9.80665 9.80665e-05 1 0.0014223
psi 6894.76 0.0689476 703.07 1
Table 52. Conversion table for pressure units

Mass flow units

Mass flow kg/s lb/s
kg/s 1 2.2046
lb/s 0.45359 1
Table 53. Conversion table for mass flow units

Volume flow units

Volume flow cubic m/s l / min cubic m/h cubic ft/s cubic ft/h USG / s USG / h
cubic m / s 1 60000 3600 35.315 127133 264.17 951019
l / min 1.6667e-05 1 0.06 1699.0 0.47195 227.12 0.063090
cubic m / h 0.00027778 16.667 1 101.94 0.028317 13.627 0.0037854
cubic ft / s 0.028317 0.00058858 0.0098096 1 0.00027778 0.13368 3.7133e-05
cubic ft / h 7.8658e-06 2.1189 35.315 3600 1 481.25 0.13368
USG / s 0.0037854 0.0044029 0.073381 7.4805 0.0020779 1 0.00027778
USG / h 1.0515e-06 15.850 264.17 26930 7.4805 3600 1
Table 54. Conversion table for volume flow units

Temperature units
Temperature K °C °F

K 1 value[°C] + 273.15 5 / 9 * (value[F] - 32) + 273.15

°C value[K] - 273.15 1 5 / 9 * (value[F] - 32)
°F 9 / 5 * (value[K] - 273.15) + 32 9 / 5 * value[°C] + 32 1
Table 55. Temperature conversion formulas

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Wärtsilä 50SG Power Plant Product Guide

Pipe dimensions metric - imperial

Europe USA
DN OD/mm NPS OD/Inch OD/mm
DN 15 21.3 ½” 0.840 21.3
DN 20 26.9 ¾” 1.050 26.7
DN 25 33.7 1” 1.315 33.4
DN 32 42.4 1 ¼” 1.660 42.2
DN 40 48.3 1 ½” 1.900 48.3
DN 50 60.3 2” 2.375 60.3
DN 65 76.1 2 ½” 2.875 73.0
DN 80 88.9 3” 3.500 88.9
DN 100 114.3 4” 4.500 114.3
DN 125 139.7 5” 5.563 141.3
DN 150 168.3 6” 6.625 168.3
DN 200 219.1 8” 8.625 219.1
DN 250 273.0 10” 10.750 273.0
DN 300 323.9 12” 12.750 323.8
DN 350 355.6 14” 14.000 355.6
DN 400 406.4 16” 16.000 406.4
DN 450 457.2 18” 18.000 457.0
DN 500 508.0 20” 20.000 508.0
DN 600 609.6 24” 24.000 610.0
DN 900 914.4 36” 36.000 914.0
DN1000 1016.8 40” 40.000 1016
DN1100 1118.0 44” 44.000 1118
DN1200 1219.0 48” 48.000 1219
DN1300 1320.0 52” 52.000 1321
DN1400 1420.0 56” 56.000 1422
Table 56. Pipe dimensions according to European and American standards and outer pipe diameters

Prefixes
T = Tera = 1 000 000 000 000 times
G = Giga = 1 000 000 000 times
M = Mega = 1 000 000 times
k = kilo = 1 000 times
m = milli = divided by 1 000

µ = micro = divided by 1 000 000

n = nano = divided by 1 000 000 000

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