Diagnosis and Solution for High-Speed Turboexpander Thrust Loading IssueDiagnosis and Solution for High-Speed Turboexpander Thrust Loading Issue

Mohamed El-AbyoukiAbu Dhabi Gas Industries Ltd (GASCO) - Abu Dhabi, UAE

and

Armando GuerreroAtlas Copco Mafi-Trench Company LLC - California, USA

Mohamed ElMohamed El--AbyoukiAbyoukiAbu Dhabi Gas Industries Ltd (GASCO) Abu Dhabi Gas Industries Ltd (GASCO) -- Abu Dhabi, UAEAbu Dhabi, UAE

andand

Armando GuerreroArmando GuerreroAtlas Copco MafiAtlas Copco Mafi--Trench Company LLCTrench Company LLC -- California, USACalifornia, USA

11stst Middle East Turbomachinery SymposiumMiddle East Turbomachinery Symposium

RoadmapRoadmap

Background

Problem Identification

Analysis

Scope

Testing

Conclusions

BackgroundBackground

Problem IdentificationProblem Identification

AnalysisAnalysis

ScopeScope

TestingTesting

ConclusionsConclusions

Bab Turboexpander PlantBab Turboexpander Plant

Plant Visit 2007Plant Visit 2007

Plant Personnel described problem during vendor site visit in 2007

High Compressor Thrust

Thrust Balancer Full Open

Operation Limited

Plant Personnel described problem Plant Personnel described problem during vendor site visit in 2007during vendor site visit in 2007

High Compressor ThrustHigh Compressor Thrust

Thrust Balancer Full OpenThrust Balancer Full Open

Operation LimitedOperation Limited

History of Bab Plant TurboexpanderHistory of Bab Plant Turboexpander

1991 re-rate for higher capacityRe-rate not factory testedAt commissioning, high compressor thrust observedFlow bypassed to allow unit operation within thrust limits

1991 re1991 re--rate for higher rate for higher capacitycapacityReRe--rate not factory testedrate not factory testedAt commissioning, high At commissioning, high compressor thrust compressor thrust observedobservedFlow bypassed to allow Flow bypassed to allow unit operation within unit operation within thrust limitsthrust limits

Bab PlantBabBab PlantPlant

Turboexpander DataTurboexpander Data

Speed: Design Speed = 24,000 RPMPower: Rated = 1,595 kWPressure: Expander = 44 barg; 17 bargTemperature: Expander = -50.3 C; -83.9 CFlow: Expander = 105,674 Kg/HrGas Handled: Natural Gas = 17.5 Mol. Wt.Manufactured: 1979; re-rated in 1991

Speed: Speed: Design Speed = 24,000 RPMDesign Speed = 24,000 RPMPower: Power: Rated = 1,595 kWRated = 1,595 kWPressure: Pressure: Expander = 44 Expander = 44 bargbarg; 17 ; 17 bargbargTemperature: Temperature: Expander = Expander = --50.3 C; 50.3 C; --83.9 C83.9 CFlow: Flow: Expander = 105,674 Kg/HrExpander = 105,674 Kg/HrGas Handled: Gas Handled: Natural Gas = 17.5 Mol. Wt.Natural Gas = 17.5 Mol. Wt.Manufactured: Manufactured: 1979; re1979; re--rated in 1991rated in 1991

Turboexpander LayoutTurboexpander Layout

EXPANDER

COMPRESSOR

Automatic Thrust Balancer (ATB)Automatic Thrust Balancer (ATB)

Thrust Venting PortThrust Venting Port

IdealIdeal

CompressorExpander

ATB Fully ClosedATB Fully Open

Thrust Capacity

1991 Design Observed1991 Design Observed

CompressorExpander

2008 Upgrade (expected)2008 Upgrade (expected)

CompressorExpander

Scope of UpgradeScope of Upgrade

Evaluation of Most Economical SolutionEvaluation of Most Economical Solution

Consider New Expander Wheel and SealConsider New Compressor Wheel and SealConsider New Expander AND Compressor Wheels/Seals

Consider New Expander Wheel and SealConsider New Expander Wheel and SealConsider New Compressor Wheel and SealConsider New Compressor Wheel and SealConsider New Expander AND Compressor Consider New Expander AND Compressor Wheels/SealsWheels/Seals

New Compressor Wheel and SealNew Compressor Wheel and SealNew Compressor Wheel and Seal

New Compressor WheelNew Compressor Wheel

3D 3D bladingblading digitized from original cast wheeldigitized from original cast wheelSolid model created for analysisSolid model created for analysis

Reverse Engineering

CNC Milled from Solid ForgingCNC Milled from Solid Forging

New Compressor WheelNew Compressor Wheel

Larger Seal Area Larger Seal Area

New Compressor WheelNew Compressor Wheel

Old = 6.25 Inch Old = 6.25 Inch New = 8.0 Inch New = 8.0 Inch

Refurbished ATB AssemblyRefurbished ATB Assembly

Full Speed Factory TestFull Speed Factory Test

ResultsResults

Factory test confirmed successful modification

Turboexpander restarted in December 2008

Thrust levels reduced as predicted

Unit now capable of full speed operation

Factory test confirmed successful Factory test confirmed successful modificationmodification

Turboexpander restarted in December 2008Turboexpander restarted in December 2008

Thrust levels reduced as predictedThrust levels reduced as predicted

Unit now capable of full speed operationUnit now capable of full speed operation

ConclusionsConclusions

Old problems warrant periodic investigation

Large gains possible from small investments

Factory testing reduces risk on upgrades

Old problems warrant periodic investigationOld problems warrant periodic investigation

Large gains possible from small investmentsLarge gains possible from small investments

Factory testing reduces risk on upgradesFactory testing reduces risk on upgrades

Thank YouThank You