FGSS Fuel Gas Supply Unit

PVU Pump Vaporizer Unit

High quality pump unit for supply LNG or methane to main engine'
The PVU is designed to supply LNG/ethane to the pressure and temperature required
by the MAN two-stroke ME-GI/GIE engines. The PVU receives cryogenic LNG/ethane
supplied by a cryogenic centrifugal pump and is subsequently pressurized by a high
pressure reciprocating pump, consisting of three cylinders actuated by linear
hydraulic pistons. The pressurized LNG/ethane flows through a compact printed
circuit heat exchanger, in which it is heated by warm glycol water. Thereafter the gas
is directed towards the gas valve train (GVT) and the engine. The gas pressure
delivered to the engine is controlled by hydraulic flow control of the pump. Individual
control of the three cryogenic pumps heads, means that the PVUs are still able to
operate with only two cold-ends in service, providing the redundancy required by the
market.

GVT Gas Valve Train

EPS Expanded Polyster Panel
PU Polyurethrane Foam
IGF Code International code of Safety for ships using Gases or Low flashpoint fuels
CMR Cargo machinery Room
Tanks For transferring LNG as a cargo IMO type B (Moss Maritime spherical tanks) and
membrane tanks mainly are used. New developments use IMO type A tanks and
IMO type C tanks. For LNG propulsion on ship other than LNG carriers, IMO type C
tank are preferable

Type B Tank, There are Type ‘B’ tanks of prismatic shape in LNG service. The prismatic Type ‘B’
MOSS tanks tank has the benefit of maximizing ship-deck. Where the prismatic shape is used, the
maximum design vapour space pressure is, as for Type ‘A’ tanks, limited to 0.7 barg.
Most Moss type vessels have 4 or 5 tanks.

Fully refrrigerated at atmospheric pressure

Type C Type ‘C’ Tanks Type ‘C’ tanks are normally spherical or cylindrical pressure vessels
having design pressures higher than 2 barg. The cylindrical vessels may be vertically
or horizontally mounted. This type of containment system is always used for semi-
pressurized and fully pressurized gas carriers.

Pressurised at ambient or lower temperature.

BOG Boil of Gases
SIGTTO Society of International Gas Tankers and Terminal Operators
ESD Emergency Shutdown System
IBS Inter Barrier Space
IS Insulation Space
S-HPS Stand-alone Hydraulic Power Supply
Operation
Dry Air During dry docking or inspection, cargo tanks which have been opened and contained humid
air, must be dried to avoid the formation of ice when they are cooled down and the formation
of corrosive agents if the humidity combines with sulfur and nitrogen oxides which might be
present in excess in the inert gas. Dry air, with a dew of -70ºC to -40ºC, can be produced by the
onboard IGG system

Inerting Cargo tanks filled with air shall be dried and inerted with inert gas supplied from the inert gas
generator on board. Inert gas shall be led into the bottom of the cargo tank through the liquid
filling line and displaced air shall be vented to the atmosphere through the vapour line and the
vent mast. Drying and inerting shall be finished when the dew point and also the oxygen
content in the cargo tank are less than the planned level.

Gassing Up This is because, inert gas contains about 14% carbon-dioxide, which will freeze at around -60ºC
and produces a white powder which can block valves, filters and nozzles.

During gassing up, the inert gas in the cargo tanks is replaced with warm LNG vapor. This is
done to remove carbon dioxide and to complete drying of the tanks.
Cool Down Cooling down is necessary to avoid excessive tank pressures (due to flash evaporation) during
bulk loading. Cool-down consists of spraying cargo liquid into a tank at a slow rate. The lower
the cargo carriage temperature, the more important the cool down procedure becomes. Before
loading a refrigerated cargo, ship’s tanks must be cooled down slowly in order to minimise
thermal stresses. The rate at which a cargo tank can be cooled, without creating high thermal
stress, depends on the design of the containment system and is typically 10°C per hour.
Reference should always be made to the ship’s operating manual to determine the allowable
cool-down rate.

LNG Fuel Tank

LNG Supply Pumps

PVU Pump and Vaporizer Unit, 3 Sets of HP pump and One HP Vaporizer

Two sets of BOG compressor, pre heater and Intercooler

GVT, Gas Valve Train for ME

Gas Valve Unit GVU for DF DG

GVU for Boiler

Utility, GW Glycol Water System, heater

Nitrogen System
FGSS LNG Pump PVU HP Pump HP Vaporizer Gas Valve Train
3x50%, cap 3800 kh/h for each Semi enclosure unit on open deck
Press. To 313 bar two sets of valve units
Forward to HP vaporizer, GW double block and bleed concept
outlet temp. -30 to -60degC, double wall piping with continuous ventilation
supplied to GVT To the fuel gas piping of main engine

LNG Pump Forcing Vaporizer Gas Valve Unit DFDE & Boiler
1 set of shell and tube type 1 set of GVU for each DFDE
forcing vaporizer FV Located in ER
2500 kg/h at 6 bar

Vapor fm. LNG Tk BOG Compressor Gas Valve Unit DFDE & Blr.
2 set of screw pump
450 kg/h each
Ptrss. Upto 6 bar
Pre-heater and After cooler
d contained humid
n and the formation
es which might be
n be produced by the

d from the inert gas

k through the liquid
vapour line and the
so the oxygen

eeze at around -60ºC

NG vapor. This is

h evaporation) during
slow rate. The lower
dure becomes. Before
in order to minimise
creating high thermal
ically 10°C per hour.
ermine the allowable
 Main engine

ous ventilation
PVU Pump Vaporizer Unit
The purpose of the Pump Vaporizer Unit (PVU) is to supply the necessary gas flow, methane or ethane, at
specified pressure and temperature for ME-GI / ME-GIE engines. To 250 to 380 bar and heat the LNG to
vapourize to ga/fluid at 35 - 55 degC.

PVU need stand alone hydraulic power supply (S-HPS)

ethane or ethane, at
nd heat the LNG to
Tank 'B' Type ‘B’ tanks can be constructed of flat surfaces or they may be of the spherical type. This type
of containment system is the subject of much more detailed stress analysis compared to Type
‘A systems. These controls must include an investigation of fatigue life and a crack propagation
analysis. These tanks may be able to withstand pressures up to 2 barg. The most common
arrangement of Type ‘B’ tank is a spherical tank as illustrated in Figure 3.2. This tank is of the
Kvaerner Moss design. Because of the enhanced design factors, a Type ‘B’ tank requires only a
partial secondary barrier in the form of a drip tray. The hold space in this design is normally
filled with dry inert gas. However, when adopting modern practice, it may be filled with dry air
provided that inerting of the space can be achieved if the vapour detection system shows cargo
leakage. A protective steel dome covers the primary barrier above deck level and insulation is
applied to the outside of the tank. The Type ‘B’ spherical tank is almost exclusively applied to
LNG ships; seldom featuring in the LPG trade.
 A Type ‘B’ tank, however, need not be spherical. There are Type ‘B’ tanks of prismatic shape in
LNG service. The prismatic Type ‘B’ tank has the benefit of maximising ship hull volumetric
efficiency and having the entire cargo tank placed beneath the main deck. Where the prismatic
shape is used, the maximum design vapour space pressure is, as for Type ‘A tanks, limited to 0.7
barg.

Type 'C' Type ‘C’ tanks are normally spherical or cylindrical pressure vessels having design pressures
higher than 2 barg. The cylindrical vessels may be vertically or horizontally mounted.

This type of containment system is always used for semi-pressurised and fully pressurised gas
carriers. Type ‘C’ tanks are designed and built to conventional pressure vessel codes and, as a
result, can be subjected to accurate stress analysis. Furthermore, design stresses are kept low.
Accordingly, no secondary barrier is required for Type ‘C’ tanks and the hold space can be filled
with either inert gas or dry air.

Type ‘C’ tanks (pressure vessels) fabricated in carbon steel having a typical design pressure of
about 18 barg. Ships with higher design pressures are in service and a few ships can accept
cargoes at pressures of up to 20 barg.

In the case of a typical fully pressurised ship (where the cargo is carried at ambient
temperature), the tanks may be designed for a maximum working pressure of about 18 barg.
For a semi-pressurised ship the cargo tanks and associated equipment are designed for a
working pressure of approximately 5 to 7 barg and a vacuum of 0.5 barg. Typically, the tank
steels for the semi-pressurised ships are capable of withstanding carriage temperatures of -48°C
for LPG or -104°C for ethylene. (Of course, an ethylene carrier may also be used to transport
LPG.)

Figure below shows Type ‘C’ tanks as fitted in a typical fully pressurised gas carrier. With such an
arrangement there is comparatively poor utilisation of the hull volume; however, this can be
improved by using intersecting pressure vessels or bi-lobe type tanks which may be designed
with a taper at the forward end of the ship.
Tier III Regulation
NOx emissions are regulated by the International Convention for the Prevention of Pollution
from Ships (MARPOL Annex VI). Under Regulation 13 of MARPOL Annex VI, 3 tiers of nitrogen
oxide emission limits have been established for engines, namely IMO Tier I, Tier II and Tier III.
Each tier limits NOx emissions to a specific value. The different tiers are based on the date the
ship's keel was laid. The Tier I NOx limit applies to engines on ships with keels laid on or after 1
January 2000 and Tier II on ships with keels laid on or after 1 January 2011. Tier I and Tier II
apply globally, and Tier III standards apply to engines installed on ships with keels laid:

On or after 1 January 2016, which operate in an existing NOx Emission Control Area (NECA),
and;
On ships constructed and operating on or after the date of adoption of a new NECA.
Based on the above, vessels with keels laid on or after 1 January 2016, operating in North
America and the U.S. Caribbean must comply with Tier III (as these NECA areas were adopted
on 1 January 2016). From 1 January 2021, the Baltic and the North Sea are also NECA areas. So,
vessels with keels laid on or after 1 January 2021, operating in the Baltic Sea or North Sea NECA,
must also be equipped with Tier III engines.

Win GD- X-DF

The WinGD X-DF engines meets the regulations of IMO’s Tier III NOx limits in gas mode in ECA
by considerable margins without any additional exhaust gas abatement measures such as EGR
or SCR.

With liquid fuel consumption for pilot ignition below 1% of total heat release and with
practically no sulphur content in LNG, X-DF technology is believed to be a reliable solution to
achieve the 0.5% global cap on sulphur in marine fuels proposed to become effective January
2020.

WinGD developed the lean burn Otto combustion process with low-pressure gas admission and
micro-pilot ignition for its two-stroke engine portfolio.

MEGI
The dual-fuel two-stroke engine is based on the combustion principle of operating on Heavy
Fuel Oil (HFO) or Marine Diesel Oil (MDO) together with high-pressure natural gas, where the
fuel is injected and burned directly as opposed to the premixed or Otto-cycle combustion.

In brief, two or three gas fuel valves inject high-pressure natural gas to the combustion chamber
and to ensure an optimally controlled combustion, a small amount of pilot oil is injected
simultaneous with the natural gas via two or three conventional fuel oil injectors.