Redundant Integrated
Turbomachinery Control for
a Refinery Cryogenic Unit
Nikhil Dukle
VP, Engineering
Energy Control Technologies
www.energycontroltechnologies.com
Copyright © 2012 Rockwell Automation, Inc. All rights reserved.
Presentation Highlights
 Common Integrated Redundant ControlLogix system for
 ESD
 Process Control
 Turbomachinery Control
 Benefits realized by using PlantPAx concept
 Advanced ECT Turbomachinery Control System
 Better lifecycle management using common spares
 Reduced maintenance costs

No specialists required to maintain blackbox systems
Integrated PlantPAx systems provides high value to
customers
Copyright © 2012 Rockwell Automation, Inc. All rights reserved.
2
Agenda
ECT Company Description
Cryogenic Process & Plant Layout
Project Description & Requirements
PlantPAx System Details
Benefits and Conclusions
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3
(ECT)
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4
ECT Background
 Specializes in design and manufacture of advanced control systems for
rotating machinery and other high energy consuming assets
 Gas Compressor Networks
 Steam & Gas Turbines and Turboexpanders
 Plant Air Systems
 Centrifuges
 Chillers
 ISO 9001:2008 Certified
 300 years of combined experience in all aspects of turbomachinery control
 Application engineering, site survey, consulting, design, simulation,
project engineering and site installation & commissioning
Copyright © 2012 Rockwell Automation, Inc. All rights reserved.
ECT Markets
 Oil and Gas




Upstream, midstream downstream
Offshore platforms and FPSOs
Refineries and petrochemical complexes
Gas Plants and LNG Plants
 Industrial / Manufacturing

Compressed Air Systems
 Biofuels


Centrifuges
Full plant controls
Copyright © 2010 Rockwell Automation, Inc. All rights reserved
Copyright © 2012 Rockwell Automation, Inc. All rights reserved.
ECT Mission
 Deliver VALUE through customer-driven
control solutions for processes and
machinery to –
 Maximize




Production
Energy efficiency
Reliability and availability
Minimize




Down time
Specialized maintenance expertise
Time to repair
Cost to repair
Copyright © 2010 Rockwell Automation, Inc. All rights reserved
Copyright © 2012 Rockwell Automation, Inc. All rights reserved.
ECT Product Portfolio
 TurboPAC®
 SurgePAC®
 PerformancePAC®



LoadPAC® & NetPAC®
SpeedPAC®
FuelPAC®
 CentrifugePACTM
 AirPAC®
 PACView®
 SimPAC®
 VibrationPACTM
Copyright © 2010 Rockwell Automation, Inc. All rights reserved
Copyright © 2012 Rockwell Automation, Inc. All rights reserved.
Cryogenic Process
and
Plant Layout
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9
Cryogenic Plant Process Flow Diagram
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10
Cryogenic Plant Process
 Recovery of C3 and C4 fraction from LPG-rich gas streams
 Source – Upstream Gas Concentration Unit and Propylene Splitter
 LPG Recovery Conditions
 Pressure: 20 bar g (medium pressure)
 Temperature: -78 ºC
 Critical Turbomachinery
 Two centrifugal compressors in series to increase gas pressure


1 Electric motor compressor unit (K-2)
1 Turbo-expander compressor unit (K-3)
 Two-stage Heat Exchanger to reduce temperature
 Remaining lean gas returned to fuel gas header system
Copyright © 2012 Rockwell Automation, Inc. All rights reserved.
11
Upgrade Project Requirements
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12
Upgrade Project Drivers
 Plant Outages, Lost Production and Equipment Wear and Tear
 High-value, high margin product (> $75,000 per day)
 ESD and Process Control System – Mitsubishi PLC
 Obsolete triple voter processor
 I/O failures & CPU halts
 Non-redundant MODBUS link to DCS gateway
 Compressor Control – CCC make S3+ surge and performance controllers
 Difficult to maintain and service black-box hardware
 Turbo-expander Control – In the Honeywell TDC 3000 DCS
 In MANUAL, difficult to AUTO start/stop, no process control
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13
New System Wish List
 High-availability System on One Platform
 ESD system for safety, environmental and asset integrity level
 Process control system
 Turbomachinery control system
 Redundant MODBUS link to the DCS gateway
 Standard components, no black-boxes
 Turbomachinery Control System
 Surge control algorithms to handle refrigeration process
 Advanced control algorithms to handle compressors in series
 Maximize liquid recovery through automated and synchronized
control of Expander IGVs and Bypass Valve
 Automated process control of critical drum pressures
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14
Competing System Offerings
 Rockwell Automation
 Redundant ControlLogix based ESD and Process control system
 Bolt-on SIL 2 ECT Turbomachinery Control System
 VersaView Panel PC HMI
 Siemens
 Redundant S7-400 based ESD system
 SI-developed Generic or Blackbox Turbomachinery Control System
 SIMATIC Panel PC HMI
 Triconex
 I/O extension to existing TMR processors with software upgrade
 Triconex proprietary Turbomachinery Pack
 Wonderware Panel PC HMI
Copyright © 2012 Rockwell Automation, Inc. All rights reserved.
15
Why Rockwell PlantPAx?
 ESD, Process and Turbomachinery Control System on common platform
 ECT Turbomachinery Control System Advantages over competition
 Guarantee to automate Turbo-expander control
 Guarantee to maximize liquid recovery
 Ability to control highly interacting series compressors
 Lowest installed cost over the life cycle of plant operation
 Within budget
 £500,000 including installation and commissioning
Copyright © 2012 Rockwell Automation, Inc. All rights reserved.
16
PlantPAx System
For
Cryogenic Unit
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17
Cryogenic Unit
PlantPAx System Specifics
 Redundant ControlLogix System with RM modules
 Independent L62 processor sets for ESD and Turbomachinery control
 Ethernet ring based IO split into three groups


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Ring #1 IO: surge control + ESD (non SIL) + process control
Ring #2 IO: ESD SIL
HMI – 15” VersaView PC with ECT ActiveX Components
 Redundant CompactLogix interface between ControlLogix and DCS



MODBUS RTU (RS232/485/232)
Communicate status, alarm, process variables data
Provide operator interface on the DCS
 Workstation
 RS Logix 5000 and ECT purpose-built monitoring software
Copyright © 2012 Rockwell Automation, Inc. All rights reserved.
18
Cryogenic Unit
PlantPAx System Architecture
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19
Cryogenic Unit
PlantPAx System IO
Module
IF8H
IF16
IR6I
OF8H
IB32
OA8D
OA16
OB16I
OB32
TOTAL
AI
16
32
36
84
AO
08
08
DI
192
192
DO
16
112
32
32
192
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20
ESD & Process Control System
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21
Process Control & Sequencing Graphic
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22
ESD Interlock Graphic
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23
ECT TurboPAC
Turbomachinery Control System
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24
Cryogenic Unit Turbomachinery
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25
Motor-driven Compressor (K-2)
Issues and Requirements
 Slow antisurge valve requires advanced surge control algorithms
 Valves are non-linear with large hysteresis and deadband
 Surges when downstream K-3 compressor trips
 Results in trip of Cryogenic Unit
 Automatic start and loading is required
 Strong de-stabilizing load interactions with downstream K-3 compressor
 Multiple mechanical, electrical and process constraints
 Motor current high limit
 Discharge pressure high limit
 Suction drum pressure low limit
Copyright © 2012 Rockwell Automation, Inc. All rights reserved.
26
Motor-driven Compressor (K-2)
ECT’s TurboPAC Control Applications
 SurgePAC1 – modulates antisurge valve
 Equivalent map coordinates invariant to suction conditions
 Surge Control with Adapter®, Preventer®, Stopper® algorithms
 Limit compressor suction pressure
 Detect excessive surge condition (3 surge cycles in 5 seconds)
 Estimate surge limit automatically with Estimator® algorithm
 Provide automatic load/unload functionality
 PerformancePAC1 – controls compressor suction throttle valve
 Control D2 drum pressure
 Limit motor current draw
 Limit compressor discharge pressure
 Provided automatic load/unload functionality
1 – equipped with Multi-Variable Constraint Control(MVCC) algorithms
Copyright © 2012 Rockwell Automation, Inc. All rights reserved.
27
Turboexpander - Compressor (K-3)
Issues and Requirements
 Slow antisurge valve requires advanced surge control algorithms
 Valves are non-linear with large hysteresis and deadband
 IGV actuator requiring innovative retrofit
 Automatic start and loading
 Strong de-stabilizing load interactions with upstream K-2 compressor
 Multiple mechanical, electrical and process constraints
 Speed high limit
 Discharge pressure high limit
 Suction drum pressure low limit
 Maximize liquids recovery
Copyright © 2012 Rockwell Automation, Inc. All rights reserved.
28
Turboexpander - Compressor (K-3)
ECT’s TurboPAC Control Applications
 SurgePAC1 – modulates ANTISURGE valve
 Equivalent map coordinates invariant to suction conditions
 Surge Control with Adapter®, Preventer®, Stopper® algorithms
 Detect excessive surge condition (3 surge cycles in 5 seconds)
 Estimate surge limit automatically with Estimator® algorithm
 Provide automatic load/unload functionality
 ExpanderPAC
 PerformancePAC1 – modulates expander IGVs


Control D-10 drum pressure (unless constrained)
Limit expander speed
Provide automatic START/STOP functionality
Be MASTER to BypassPAC slave

Control D-10 drum pressure (if PerformancePAC is unavailable)



BypassPAC1 – modulates expander BYPASS valve
1 – equipped with Multi-Variable Constraint Control (MVCC) algorithms
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29
TurboPAC Control System Diagram
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30
K-3 & K-2 Cascaded Trip Causes
 Cryogenic Unit trips if K-2 trips
 Can continue to operate if K-3 trips without tripping K-2
 K-3 can be restarted
 Older blackbox surge control system could not prevent K-2 from surging
and tripping when K-3 tripped.
 If K-3 tripped, K-2 would trip and Cryo Unit would trip
 K-3 would trip because process disturbances could not be handled
 K-3 was operated in MANUAL mode and thus could not correct the
process
 ECT’s TurboPAC System prevented surging of K-2 surge when K-3
tripped
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31
TurboPAC Features
Interaction Control and Surge Preventer
 ECT’s TurboPAC System prevents surging of K-2 when K-3 trip – Why?
 Reason #1: K-3 can be operated in AUTO mode
 Mechanical retrofit of IGV actuator
 Integrated IGV and Bypass Valve control
 Reason #2: Surge Preventer® and Surge Adapter® Algorithms
 Allow managing disturbances to compressors in series
 Automatically adjust control response to antisurge valves and
capacity control elements depending on the size of the disturbance,
speed of the disturbance and location of compressor operating point
 Reason #3: Interaction Control Algorithm
 Intelligent, directional decoupling of process loops
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32
ECT’s PACView Software
High-speed Recorder
 K-2 compressor surge test
 Note that SurgePAC allows only one surge cycle during test
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33
ECT’s PACView Software
High-speed Recorder
 Automatic Loading of the process after K-2 compressor start
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34
ECT’s High-speed Recorder Software
 Automatic start of K-3 Turboexpander-compressor

Process control transitions from Bypass Valve (EX1_Out) to IGVs (PC1_Out)
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35
K-2 Operator Interface
ECT’s PACView ActiveX Faceplates
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36
K-3 Operator Interface
ECT’s PACView ActiveX Faceplates
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37
Turbomachinery Monitoring
ECT’s ActiveX Dynamic Compressor Map
 Shows compressor available operating
envelope
 Shows current operation against
expected performance
 Monitors compressor performance
 Shows ECT’s equivalent map
coordinate system (Rc vs Equivalent
Flow) that is invariant to suction
conditions
 Ability to view in engineering units as –
 Rc vs Actual Flow
 Polytropic Head vs Actual Flow
 Pd vs Actual Flow
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38
Benefits and Conclusions
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39
Benefits Realized
 Meets required SIL levels, previously unachievable
 Increased uptime by eliminating trips due to legacy system shortcomings
 Average cost per unit trip ~ $50K
 > 10 trips per year
 ECT TurboPAC Control System Improvements
 Prevents cascaded compressor trips
 Reduces machinery wear
 Eliminates potential for over-speed from MANUAL starts
 Eliminates de-stabilizing interactions between series compressors
 Ability to customize control strategy
Payback of less than 1 year on equipment
Copyright © 2012 Rockwell Automation, Inc. All rights reserved.
40
Conclusions
 Project completed on schedule and within budget
 Benefits realized by using PlantPAx
 ECT’s turbomachinery expertise
 Common components allow better lifecycle management
 Reduced maintenance costs

No specialists required to maintain blackbox systems
 One platform system for the entire unit
No support calls since handover one year ago
Integrated PlantPAx systems provides high value to
customers
Copyright © 2012 Rockwell Automation, Inc. All rights reserved.
41
Questions
Name – Nikhil Dukle
Title – VP, Engineering
Date – 5-6 November 2012
Copyright © 2012 Rockwell Automation, Inc. All rights reserved.