Turbomachinery Controls
ISA Will-DuPage
Presented by Hector Buchelly
May 2013
© 2010 Invensys. All Rights Reserved. The names, logos, and taglines identifying the products and services of Invensys are proprietary marks of Invensys or its subsidiaries. All third
party trademarks and service marks are the proprietary marks of their respective owners.
Objectives
Turbomachinery Scope
Technical Solutions
Surge Control
Mechanical Retrofit
Slide 2
Rotating Equipment Scope
Prime Movers
Steam Turbine
Driven Equipment Auxiliaries
Generator
AVR
Actuator with
LVDTs
Gas Turbine
Compressor Compressor
Mechanical
Performance
Retrofit
and Motor
Protection Lube Oil
Seal Gas
MCC
Hydro-Turbine
TMC Proficiencies
Steam Turbines Gas Turbines Compressors
Integrated
Turbine/
Generators
Load Control
Solutions
TMC Offering Segmentation
Services
Nuclear TM Compressors
Utility/Power Mechanical
TM Retrofit
Steam Turbines
AEG-Kanis ABB
Dresser Turbodyne Dresser-Rand Pwr. A/S
Mitsubishi Hvy. Ind. Nuovo Pignone
ASEA STAL Allis-Chalmers Corp.
Dresser-Rand Elliott Company Shin Nippon
Siemens AG Bharat Heavy Ind. Ltd.
Steam Turbines
GEC Turbine Ltd. General Electric Co.
Murray Turbomachinery Westinghouse
Borsig Coppus Engineering
Garrett Turb. Eng. Co. Ingersoll Rand Co.
Terry Corporation Worthington
Carrier Corporation DeLaval
Kawasaki Heavy Ind.
Gas Turbines
• Allison: 501 • Rolls-Royce: RB211,
• Avon: 1533 Olympus
• BBC: Frame 11 • Ruston: TB3000,
• GE: Frame 3, Frame 5, TB4000, TB5000
Frame 7 • Solar: Centaur T48
• GE LM 2500 • Sulzer GT10
• Hispano-Suiza: 1202
• Westinghouse: W50,
• Pratt & Whitney: FT4, W101, W191, W251,
GG4, Twin Pac, Hi-Cap,
ST18 W352, W501
Process Application
Olefins Plants
• Furnace Gas
• Propylene Refrigeration
• Ethylene Refrigeration
Ammonia/Fertilizer
• Syn Gas
• Process Air
• Ammonia Refrigeration
• Feed Gas
• Carbon Dioxide
Nitric Acid—Process Air
Acrylic Acid—Process Air
Power Plants/Utilities
Process Application
Refinery Gas Separation
• FCCU Air Blower • Residual Gas
• Cat Gas • Propane Refrigeration
• Hydrogen Gas Pipeline
• Plant Air LNG
Compressor Test Stand
Turbomachinery
Control Solutions
© 2010 Invensys. All Rights Reserved. The names, logos, and taglines identifying the products and services of Invensys are proprietary marks of Invensys or its subsidiaries. All third
party trademarks and service marks are the proprietary marks of their respective owners.
Slide 11 © Invensys 3-Aug-10 Invensys proprietary & confidential
Project Execution
1. Studies or Assesments
2. Hold Kickoff Meeting
3. Generate Project Basis of Design Document
4. Develop and Test Logic
5. Perform Factory Acceptance Test Procedure (FAT)
6. Ship Equipment
7. Develop Site Acceptance Test (SAT) and Surge
Testing
8. Perform SAT and Commissioning
Compressors
Governor Performance Surge
• Steam • Pressure • Single Valve
Turbines • Flow • Multi Valve
• Motors • Decoupling • Refrigeration
• Gas Turbines • Load Sharing
• Sequencing
Mechanical Retrofit
Single-Valve and Two-Valve Actuators
Speed Sensing
Systems: Overspeed, Trip, Multi-Valve
Hydraulic Pressure Units
TMC Solutions Interaction
Simulation Fast Trending
Control Program HMI
Critical Project Questions
• System
Will my compression system perform per the design?
• Control Strategy Development
What is the best way to control my system?
• Control Checkout and Tuning
Are the controls configured correctly and tuned well?
• Operator Training
Can I use my model to train my operators?
System
Verify the compressor system before the
FEED or commissioning:
• Compressor specifications
• Anti-surge valve size, characteristics,
stroke time
Check system performance at different
operating conditions:
• Compressor trips, driver failure, loss
of instrument air, etc.
• Valve opening time, changing
molecular weight, etc.
• Compressor start-up from cold or hot
standby
Establish Control Strategy
• Determine the best anti-
surge, performance control
approaches
• Test decoupling control
algorithms
• Establish start-up and shut-
down sequencing, start-up
guide vane position, T&T
valve position
Control Logic Checkout and Tuning
• Determine effectiveness of
controls
• Debug control logic on the
system rather than in the
field
• Establish initial controller
tuning
• Evaluate necessary
overrides for particular
upsets
TMC Process Modeling
Recycle valve Intercoolers Piping and Knock Out
critical flow drum volumes for
Performance accurate transients
Curves
Fluid feed
composition
Vapor-Liquid
Motor torque
Induction motor torque curve
2.5 Shaft rotating
Equilibrium
curves
2
inertia
“Flash”
1.5
Torque factor
1
Series1
0.5
0
0 0.2 0.4 0.6 0.8 1 1.2
-0.5
-1
speed - nornalized
TMC Dynamic Modeling Deliverables
Transmitter Outputs
1. Predictive Dynamic Process Model Temperatures
Pressures
2. Validated Turbomachinery Controls Flows
Limit Switches, etc.
3. Report with Lessons Learned and Key Recommendations
Dynamic
4. Operator Process
Training Model (optional)
System Turbomachinery Controls
Controller Outputs
Valve Positions
Speed
Trip Signals, etc.
The Non-Integrated Turbine
Control System
Non-Integrated Turbine Control System
Non-Integrated System
Different vendors are involved in and responsible for
control system components:
• Packager provides vibration monitor
• Compressor vendor or EPC contractor provides
surge and performance control
• EPC contractor provides interlocks
• Site performs integration testing
The Integrated Turbine
Control System
Integrated Control System
Integration Advantages
1. Reduces Space Requirements
2. Lowers Costs For:
• Procurement
• Engineering
• Installation
• Field Instrumentation
3. Eliminates Controller-Based:
• Communication Delays
• Interconnection
• Conflicts
Rotating
Equipment
Steam Turbines
Two Valve Three Valve
Single (single (double
Reheat
Valve extraction/ extraction/
admission) admission)
System Overview
Steam Turbine Sequencing
Fast Trending Sequence Capture
Compressor
Surge Control
Strategies
Minimum Flow Control
Pd
Ps
h
Ps
Maximum Pressure Control
Pd
Ps
h
Ps
Surge Control Basics
SIC
ST FT
PT
PIC TT
PT PT TT
UIC
FY
• Define operating point by measuring variables
• Compare with controller setpoint (surge
control line)
• Vary recycle (blow-off) to control compressor
on surge control line
Recycle Valve? What’s That?
SIC
ST FT
PT
PIC TT
PT PT TT
UIC
FY
Slide 37
Surge Control Basics
Opening the recycle valve helps the compressor avoid
surge by:
Re-circulating flow back
to the compressor inlet
Relieving resistance in
compressor discharge
network, allowing flow to
increase
The Surge Cycle
Pressure
3
2
4. Flow reverses as
4
discharge pressure drops
5 1 5. Drop in discharge
pressure re-establishes
forward flow (compressor
Flow
resumes full flow)
1. System resistance increases
discharge pressure required (operating Since resistance has not
point moves up the curve) changed, surge will
continue until the cycle is
2. Operating point nears the surge broken.
limit
3. Operating point goes into the surge
region
Slide 39
The Surge Cycle
The operating point can A complete surge cycle
move from stability into takes from 1/2 to 3
surge in fewer than 50 seconds, depending on
milliseconds. compressor size and
piping volume.
Slide 40
Why is Surge Bad?
It causes process upset because of flow reversals.
It damages seals.
It causes catastrophic failure of the compressor
when it is severe.
Slide 41
How Can Surge be Prevented?
• By accurately determining the operating point
• Through the surge controller’s anticipatory action
• By opening the recycle valve to decrease
pressure ratio and increase flow through
compressor
Slide 42
Control Features
Triconex Surge Control Features
• Surge Controller Setpoint Hover
• Automatic Adjustment of Safety Margin
• Independent Proportional Term
• Adaptive Tuning
• Fast Opening/Slow Closing of Recycle Valve
• Manual Recycle Valve Control Options
Slide 44
Traditional Surge Line
5 Surge
Line
Speed
Curves
4
Hp 3
1
0 20 40 60 80 10%
Flow 0
Slide
45
Compressor Performance
Hp
Q2 (ICFM)
• The compressor performance map can be redrawn as
the polytropic head vs. the inlet volume flow squared.
• The relationship between head and flow is not
changed by this modification.
76
78
80
81
80
78
76
73
67
Polytropic
Head
Hp
0 10 20 30 40 50 60 70 80
100
80
Polytropic
Efficiency 60
h
p
40
20
0 10 20 30 40 50 60 70 80
Flow, Q
The Universal Surge Curve
P
( ) -1
P
2
h
P1
Universal Surge Line
Head Term
Pd
100% N
Ps 90% N
80% N
hs
Flow Term
Ps
The universal surge line is valid for all changes in
molecular weight and suction pressure.
Slide
49
Universal Surge Line
5 Surge
Line
Speed
Curves
4
Pd
__
Ps
1
0 20 40 60 80 10%
h
__ 0
Ps
Slide
50
Surge Margin
Safety Margin
Surge Control Features
• Universal Surge Line
• Automatic Adjustment of Safety Margin
• Independent Proportional Term
• Adaptive Tuning
• Fast Opening/Slow Closing of Recycle Valve
• Manual Recycle Valve Control Options
Slide 53
Setpoint Hover Feature
Surge Control Features
• Universal Surge Line
• Surge Controller Setpoint Hover
• Independent Proportional Term
• Adaptive Tuning
• Fast Opening/Slow Closing of Recycle Valve
• Manual Recycle Valve Control Options
Slide 55
Control Line Recalibration
Control Line
5 Surge Line Recalibrated
Control Line
Current
Operating
Point
4
Pd
__
Ps
1
0 20 40 60 80 100%
h
__
Ps
Slide
56
Surge Control Features
• Universal Surge Line
• Surge Controller Setpoint Hover
• Automatic Adjustment of Safety Margin
• Adaptive Tuning
• Fast Opening/Slow Closing of Recycle Valve
• Manual Recycle Valve Control Options
Slide 57
Surge Override
Surge
Override Control Line
Line
5 Surge
Line
0%
4
Pd Valve Output
Ps 100%
1
0 20 40 60 80 100%
h
Ps
Slide
58
Surge Control Features
• Universal Surge Line
• Surge Controller Setpoint Hover
• Automatic Adjustment of Safety Margin
• Independent Surge Override
• Fast Opening/Slow Closing of Recycle Valve
• Manual Recycle Valve Control Options
Slide 59
Adaptive Tuning
Surge Control Features
• Universal Surge Line
• Surge Controller Setpoint Hover
• Automatic Adjustment of Safety Margin
• Independent Surge Override
• Adaptive Tuning
• Manual Recycle Valve Control Options
Slide 61
Recycle Valve Opening/Closing
• Fast Opening
Quickly responds to surge condition, but does not
exceed response time of system
• Slow Closing
Allows turbine speed controller/process cascade
controller to smoothly adjust to new process
operating conditions
Slide 62
Surge Control Features
• Universal Surge Line
• Surge Controller Setpoint Hover
• Automatic Adjustment of Safety Margin
• Independent Surge Override
• Adaptive Tuning
• Fast Opening/Slow Closing of Recycle Valve
Slide 63
Manual Recycle Valve Control
Partial Authority
• Operator is allowed to open the recycle valve only when
his/her command is higher than the surge controller
demand
• Operator cannot close the recycle valve below the surge
controller demand
Full Authority
• Operator is allowed to close and open the recycle valve
with no surge protection
• Used to stroke test recycle valve prior to start-up
• Used in some fallback scenarios
Slide 64
Performance Control
Performance Control
The objective of a control loop is to operate a process:
• Within the operating zone
• In safe and stable manner with minimum human
interaction
• In a way that achieves operational design objectives with
optimum efficiency
Slide 66
Performance Control
How can we manipulate the capacity through the compressor to
influence the process?
Performance control can be accomplished in three ways:
1. By varying compressor speed via turbine or variable
frequency drive (VFD)
2. By using an inlet throttling valve for a constant speed
machine
3. By opening and closing the anti-surge valve (not very
efficient)
Slide 67
Decoupling Capacity
Control
Decoupling Capacity Control
The decoupling algorithm does the following:
• Absorbs fast load changes until compressor
speed/process valve can respond
• Prevents capacity control from driving compressor
into surge
• Decouples performance controller and surge
controller to prevent undesired interaction at low
rates
Slide 69
Decoupling Capacity Control
Slide 70
Surge Control and Capacity Control
Slide 71
Surge Control
Slide 72
Capacity/Decouple Control
Slide 73
Mechanical
Retrofit
Magnetic Pickups
Speed Gear
• Speed Gear
• Speed Probe
Mounting Bracket
• Speed Probes
Linear Variable Differential Transformer
Slide 78
78
