Lng Plant Process Useful

DRIVER SELECTION FORDRIVER SELECTION FORLNG COMPRESSORS LNG COMPRESSORS

1414thth December 2004December 2004

Dr Sib AkhtarDr Sib AkhtarMSE (Consultants) LtdMSE (Consultants) Ltd

Carshalton, Surrey SM5 2HWCarshalton, Surrey SM5 [email protected]@mse.co.uk

http://www.mse.co.uk Tel: 020 8773 4500http://www.mse.co.uk Tel: 020 8773 4500

© MSE 2004

Driver Selection for LNG CompressorsDriver Selection for LNG CompressorsDriver Selection for LNG Compressors

Introduction

Drivers Used in Past & Present Projects

Factors Influencing Driver Selection

Potential Future Applications

Pros & Cons of:Steam TurbinesIndustrial Gas TurbinesAero-derivative Gas TurbinesElectric Motors

Conclusions and Observations

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IntroductionIntroductionIntroductionHistoryEarly LNG Trains Steam DrivenDevelopment of Gas TurbinesThe LNG Growth Pause

US & UK became self sufficient in GasJapan and later Korea needed secure energy-LNGJapan remains the biggest importer of LNG

Re-emergence of LNG Demand New MarketsGas Shortages in US Re-opening of LNG terminalsExpansion of LNG in Europe UK to become net importer of Gas

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Common LNG Process SystemsCommon LNG Process SystemsCommon LNG Process Systems

Phillips Cascade ProcessThree Pure Components

PropaneEthyleneMethane

APCI (Air Products)Two Components

Propane Mixed Component Refrigerant

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New Emerging LNG Process SystemsNew Emerging LNG Process SystemsNew Emerging LNG Process Systems

Linde Process Three Mixed Refrigerants

Axens Liquefin ProcessDual Mixed Refrigerant

Shell ProcessDual Mixed Refrigerant

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Factors Influencing Compressor Driver SelectionFactors Influencing Factors Influencing Compressor Driver SelectionCompressor Driver Selection

Plant Capacity

Process Used – Choice and Number of Refrigerant Streams

Compressor Configuration

Plant Location; Ambient Conditions

Plant Availability

Operational Flexibility

Economic Factors - CAPEX & OPEX

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Gas Trade FlowsGas Trade FlowsGas Trade Flows

Source: Energy Information Administration – The Global LNG Market Status & Outlook

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LNG Import CapacityLNG Import CapacityLNG Import Capacity


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LNG Export CapacityLNG Export CapacityLNG Export Capacity


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LNG ProcessesLNG ProcessesLNG Processes

Phillips Optimised Cascade and Air Products (APCI) processes dominate the LNG plants currently under design, construction & operation

New processes include:Axens (DMR)Linde (Statoil)Turbo-Expander (BHP)

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Phillips Cascade ProcessPhillips Cascade ProcessPhillips Cascade Process

Many plant still being designed and built using the cascade process – simple and reliable

Three pure components used for refrigeration:Propane pre-coolingEthyleneMethane

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Propane pre-coolingCentrifugal compressorsTypically 2 x ~30 MW Gas Turbines (e.g. Frame 5)

Ethylene and Methane cyclesCentrifugal compressorsTypically 2 x ~30 MW Gas Turbines (e.g. Frame 5) for each cycle

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Phillips Cascade ProcessALNG – TrinidadPhillips Cascade ProcessPhillips Cascade ProcessALNG ALNG –– TrinidadTrinidad

Propane pre-coolingCentrifugal compressors2 x Frame 5 C – upgraded to D

Ethylene and Methane cyclesCentrifugal compressors2 x Frame 5 C upgraded to D for each cycle

Plant Capacity 3 MTPA – Raised to 3.3 MTPA

High Availability 95-96%

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Phillips Cascade ProcessALNG – Optimised DesignPhillips Cascade ProcessPhillips Cascade ProcessALNG ALNG –– Optimised DesignOptimised Design

Phillips Cascade Process

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Simple to design and operateSimple cycle Frame 5 gas turbines mechanical driveNo helper turbine or large motor needed for start-upIncreased size with two gas turbine trains for each refrigerant processParallel compressor trains avoids capacity limitsIncreased CAPEX due to more (six) trains offset by increased availability 95-96% with parallel train operationLoss of one train does not cause plant shut downProduction carries on with reduced capacity Refrigerant and exchangers temperature not affected by one train trip enabling quick restart

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APCI ProcessAPCI ProcessAPCI Process

Most of existing plant are using the APCI process with 3 – 3.3 MTPA Fr 6 / Fr 7 combination

Train capacities up to 4.7 MTPA built or under construction using Fr 7 / Fr 7 combination

Higher Capacities to 7.9 MTPA being announced with Frame 9 GT

Two main refrigeration cycles:Propane pre-coolingMixed refrigerant liquefaction and sub-cooling

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Propane pre-coolingCentrifugal compressor (to 15 – 25 bar)Side-streams at 3 pressure levelsTypically requires a ~40 MW Gas Turbine (e.g. Frame 6) plus Helper Motor or Steam TurbineCompressor sizes reaching maximum capacity limitsAdded aerodynamic constraint; high blade Mach numbers due to high mole weight of propane (44)Prevents utilisation of full power from larger gas turbines (Frame 7)

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Mixed refrigerant liquefaction and sub-coolingAxial LP for Shell Advised PlantCentrifugal HP compressor (45 – 48 bar)Typically requires ~70 MW Gas Turbine (e.g. Frame 7) plus Helper Motor or Steam Turbine

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ELLIOTT IN LNGA HISTORY OF FIRSTS

World’s first large-scale liquefaction plant (CAMEL – Arzew, Algeria) World’s first baseload refrigeration plant (Phillips - Kenai, Alaska)World’s first gas turbine driven LNG compressors (Phillips, Alaska)World’s first single-mixed refrigerant (APCI) process compression (Esso (Exxon) – Marsa el-Brega, Libya)World’s first dual-shaft (GE Frame 5) gas turbine driven compressor strings (P.T. Arun (Mobil) – Indonesia)World’s first C3-MR (APCI) process compression (P.T.Arun – Indonesia)World’s first GE Frame 7 driven Propane MR compressor (Ras Gas 1&2 – Ras Laffan, Qatar)World’s largest four-section Propane MR compressor (Ras Gas 3 – Ras Laffan, Qatar - UNDER CONSTRUCTION)

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Partial List - ELLIOTT LNG Plants

End User Process Capacity MM T/Yr # of Units Service C.A.M.E.L.

Arzew, Algeria Cascade 1.3 3

3 3 3 3

Propane Ethylene

Methane 1 Methane 2

Vapor

Phillips Petroleum Kenai, Alaska

Cascade 1.1 2 2 1

Propane Methane 1 Methane 2

Esso Libya Marsa El Brega,

Libya

Mixed Refrigerant 3.2 4 4

MR-1 MR-2

Sonatrach Arzew, Algeria

Mixed Refrigerant &

Propane

16.4 6 6 6

MR-1 MR-2

Propane

Abu Dhabi Liquefaction Co.

Das Island, Abu Dhabi

Mixed Refrigerant &

Propane

3.0 2 2 2 2

Feed Gas Feed Gas Feed Gas Propane

P. T. Arun Liquefaction Co. Lhokseumawe,

Indonesia

Mixed Refrigerant &

Propane

9.0 6 6 6

MR-1 MR-2

Propane

Ras Laffan Liquefaction Co.

Qatar

Mixed Refrigerant &

Propane

6.0 2 2 2

MR-1 MR-2

Propane

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Mixed refrigerant liquefaction and sub-cooling

Large volumetric flows

Two casing arrangements (LP and an HP)Axial LP / centrifugal HP compressor (45 – 48 bar)Typically requires ~70 MW Gas Turbine (e.g. Frame 7) plus Helper Motor or Steam TurbineLP and HP compressor speeds compromisedLP axial compressor (higher efficiency)HP centrifugal compressor

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APCI

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Example of APCI Process EvolutionExample of APCI Process EvolutionExample of APCI Process Evolution

Petronas MLNG, located in Bintulu, Sarawak

First trains designed in the ’70s:3 x Centrifugal compressors3 x Steam Turbine drivers ~ 37 MW each

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Example of APCI Process EvolutionExample of APCI Process EvolutionExample of APCI Process EvolutionExtension trains designed in the ’90s:

Propane pre-cooling:Centrifugal compressor30 MW Gas Turbine & 7 MW Steam Turbine

Mixed component refrigeration (MCR):LP axial compressor & HP centrifugal compressor64 MW Gas Turbine & 7 MW Steam Turbine

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RAS GAS I & II – RAS LAFFAN, QATARRAS GAS I & II RAS GAS I & II –– RAS LAFFAN, QATARRAS LAFFAN, QATAR

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RAS GAS III (&IV), RAS LAFFAN, QATARUNDER CONSTRUCTION

RAS GAS III (&IV), RAS LAFFAN, QATARRAS GAS III (&IV), RAS LAFFAN, QATARUNDER CONSTRUCTIONUNDER CONSTRUCTION

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Axens Liquefin ProcessAxensAxens LiquefinLiquefin ProcessProcess

Mixed refrigerants for pre-cooling, liquefaction and sub-cooling dutiesLiquefin development studies presently oriented towards increasing capacity to 6 MTPA with:

2 x Frame 7 Gas Turbines for main compression2 x Frame 5 Gas Turbines for power generation

Higher capacities possible using:Frame 9 GTsElectric motorsSteam turbines etc.

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Similar to APCI with Propane compressor replaced with Mixed Refrigerant for pre-cooling

Allows more balanced flows, refrigeration loads and power between the two compressors

Avoids the process design limits associated with Propane compressors

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Axens

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Shell DMR ProcessRef O G J July 16 2001

Shell DMR ProcessShell DMR ProcessRef O G J July 16 2001Ref O G J July 16 2001

Similar to Axens but with twin parallel compressor trains for each process stream

Use of aero-derivative or VSD motors

Shell claim 4.5 - 5.5 MTPA and lower cost

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Linde ProcessLinde ProcessLinde Process

Mixed refrigerants for pre-cooling, liquefaction and sub-cooling duties

Minimum of Three Gas Turbine or electric motors needed for compressor driver

4.3 MTPA plant under construction with VSD motor drivers and onsite power generation with aero-derivative gas turbines

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Linde ProcessLinde ProcessLinde Process

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Process Design, Driver Ratings& Compressor ConfigurationProcess Design, Driver RatingsProcess Design, Driver Ratings& Compressor Configuration& Compressor Configuration

APCI process uses larger and larger gas turbines to reduce CAPEX in a single train configuration; bigger gas turbine have lower $/kWFrame 7EA used for Mixed RefrigerantFrame 6 being replaced by Frame 7 for Propane for larger plantsThe plants are “single train” i.e. each machine is designed for 100% capacity and arranged in series

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Process Design, Driver Ratings& Compressor ConfigurationProcess Design, Driver RatingsProcess Design, Driver Ratings& Compressor Configuration& Compressor Configuration

Phillips Optimised Cascade process have used 2x50% compressor configuration and achieved cost savings and high availability

Shell DMR process appears to favour twin train configuration and achieves 4.5 - 5.5 MTPA with larger aero-derivative

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Gas Turbines Used in LNG PlantGas Turbines Used in LNG PlantGas Turbines Used in LNG Plant

Heavy Duty Gas Turbines:Mechanical drive shown in bluePower generation shown in yellow

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Aero-Derivative Gas Turbines for LNG Plant – Potential AeroAero--Derivative Gas Turbines Derivative Gas Turbines for LNG Plant for LNG Plant –– Potential Potential

Aero-derivative Gas Turbines:

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Combined Cycles and LNG Plant – PotentialCombined Cycles and LNG Combined Cycles and LNG Plant Plant –– PotentialPotential

Combined Cycles:ISO Power (kW) Heat Rate (kJ/kWh) Efficiency (%)

LM1600PE 18591 7605 45LM2500PE 31048 7186 50LM2500+ 6STG 40912 6981 52LM6000PC 55007 6764 53LM6000PD Sprint 59142 6876 52RB211-24GT RT62 39760 7005 51.4Trent 50 64458 6780 53.1Trent 60 72268 7189 50.1

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Economies of ScaleEconomies of ScaleEconomies of Scale

Source: Gower and Howard, “Changing Economics of Gas Transportation”

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Economies of ScaleEconomies of ScaleEconomies of Scale

Source: Introduction to LNG, University of Houston Institute for Energy, Law and Enterprise

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Steam Turbines - ProsSteam Turbines Steam Turbines -- ProsPros

Several established VendorsSize; may be built to exact process specificationMechanical drive up to 130 MW not a problemConstant speed power generation 600–1100 MWHigh reliability; 30 years life is achievableHigh availability; compressors & steam turbines may both achieve 3 years non-stop operation, no need for inspectionSteam is often required elsewhere in processMixed fuel; boilers can utilise varying fuel mix whereas gas turbines require fuel specification to be maintainedHigher thermodynamic efficiency than simple cycle GT (but lower efficiency than GT-steam combined cycle)Power output relatively unaffected by ambient conditions

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Steam Turbines - ConsSteam Turbines Steam Turbines -- ConsCons

Perceived as old “Victorian” technology

Physically very large; boilers, condensers, desalination plant (for make-up water), water polishing plant etc.

CAPEX of steam turbine plant is higher than simple cycle GT (but similar cost to combined cycle)

Overhaul of steam turbine similar to large frame GT (but interval between overhauls is twice as long!)

Added complexity in steam auxiliaries, including feed heating, boiler feed pumps etc.

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Industrial Gas Turbines - ProsIndustrial Gas Turbines Industrial Gas Turbines -- ProsProsSimple cycle GT is uncomplicated in its design

Low CAPEX

Economies of scale when using large frame GTs

Extensive operational experience with mechanical drive applications

Large population; perceived as low risk technology

Skid mounted; easier to install than a steam system

Smaller plant footprint; less extensive civil works

Lower NOX than Aero-derivative GT

Range of sizes available:

~ 110 MWFrame 9~ 75 MWFrame 7~ 40 MWFrame 6~ 30 MWFrame 5

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Industrial Gas Turbines - ConsIndustrial Gas Turbines Industrial Gas Turbines -- ConsCons

Paucity of Vendors!Low thermal efficiency, high CO2 emissionsMaintenance is intensive, involving prolonged on-site work which reduces plant availabilityFixed sizes and fixed optimal speedsProcess and compressors must be designed around the GT (unlike steam turbines)Process may not make full use of the GT powerPower output highly sensitive to ambient conditions e.g. typical large GT:

At 40 °C~82% power

At 30 °C~88% power

At 20 °C~95% power

At 15 °C 100% power

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Aero-Derivative Gas Turbines - ProsAeroAero--Derivative Gas Turbines Derivative Gas Turbines -- ProsProsHigher thermal efficiency than Industrial GT; 38-42% compared to 28-32% for similar size Industrial GTs in simple cycle

Smaller footprint area than Industrial GT because of aero design

Shorter maintenance period; modular design allows gas engine and power turbine sections to be swapped out

Off-site maintenance (in factory)

Thus, higher plant availability

Most engines have free power turbines for variable speed operation (within a range)

Large helper motors or steam turbines may not be needed for start-up

Range of sizes available:

~ 55 MWTrent~ 40 MWLM6000~ 30 MWRB211

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Aero-Derivative Gas Turbines - ConsAeroAero--Derivative Gas Turbines Derivative Gas Turbines -- ConsConsPaucity of Vendors (essentially only 2)!Higher NOX than Industrial GTsEngines need more care and maintenance due to higher operating pressures and temperatures and design complexityFixed sizes and fixed optimal speedsProcess and compressors must be designed around the GT (unlike steam turbines)Process may not make full use of the GT powerPower output highly sensitive to ambient conditionsFuel quality is critical – even more than in Industrials!Limited operating experience for LNG, although extensive for offshore mechanical drive and power generationPowers greater than 60 MW not available in simple cycleDry Low Emissions (NOX) technology adds complexityHigher risk technology than Industrial GTs

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Combined Cycles - ProsCombined Cycles Combined Cycles -- ProsPros

Mitigates some of the cons of Industrial GTs

Adds some of the pros of Steam Turbines

Essentially, 50% extra power / 50% extra thermal efficiency / 50% lower CO2 emissions

Allows optimisation of process and compressors

Steam turbine can be used for start-up and additional power

Steam may be required elsewhere in the process

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Combined Cycles - ConsCombined Cycles Combined Cycles -- ConsCons

High CAPEX, increased complexity, more extensive civil works… same as for Steam Turbine

Combined cycles are not presently favoured by LNG plant designers, but may be considered when CO2 is taxed!

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Variable Speed Electric Motors - ProsVariable Speed Electric Motors Variable Speed Electric Motors -- ProsProsCan be made to suit, allowing optimisation of process and compressorsHigher availability of LNG plant than if using GTs or Steam TurbinesReduced manning levelsMay avoid gearboxes for 3000-3600 rpm compressor speeds (large flow capacity compressors)Power generation may be off-siteLower CAPEX if power is bought from the gridSimple layout, reduced civil works

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Variable Speed Electric Motors - ConsVariable Speed Electric Motors Variable Speed Electric Motors -- ConsConsMost LNG plant are in remote locations; off-site power generation of 400-500 MW not available!

Very high CAPEX if power generation is built alongside LNG

High OPEX (although savings may be possible)

Limited experience with high power VSDs; 45-55 MW is achievable, 65 MW is the maximum

Electrical issues at compressor start-up; grid peak current and fault levels

Power generation using GTs must happen somewhere; CO2, NOX and sensitivity to ambient conditions is similar to a GT (unless power generation is using a combined cycle)

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Conclusions and ObservationsConclusions and ObservationsConclusions and ObservationsLNG drivers are predominately Industrial Heavy Duty Gas Turbines e.g. GE Frames 5, 6, 7 … even 9!Frame 5s generally used on older LNG plant, although ALNG in Trinidad was recently fitted with Frame 5Ds; these are demonstrating high overall availability at low CAPEX… 3.3 MTPA with 6 x Fr 5Fr 6 / Fr 7 combinations replaced Steam Turbines at MLNGNow Fr 6 / Fr 7 commonly used at NLNG, Oman LNG, Qatar LNG… 3.3 – 3.5 MTPAFr 7 / Fr 7 combinations used at Qatar LNG, but with poor use ofGT power because of non-optimal process, process had to be redesigned… ~4 MTPALarger and larger trains are pushing the limits of compressor technology i.e. Axials for Mixed Refrigerant and largest centrifugals for Propane

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Conclusions and ObservationsConclusions and ObservationsConclusions and Observations

When parallel trains are used (instead of series) e.g. ALNG:

Smaller driver sizes can be used e.g. Frame 5sCompressor capacities are halved, so centrifugals may be used instead of axialsPlant availability is enhancedImproved operability, re-starting after a train failure is simpler and quickerPlant costs are surprisingly lower

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Lng Plant Process Useful