20TH SYMPOSIUM ON INDUSTRIAL APPLICATIONS OF GAS TURBINES

Presented at the 20th Symposium on Industrial Application of Gas Turbines (IAGT)Banff, Alberta, Canada - October 2013

The IAGT Committee shall not be responsible for statements or opinions advanced in technical papers or in symposium or meeting discussions.

by

Klaus Brun / Southwest Research InstituteRainer Kurz / Solar Turbines Inc.Marybeth Nored / Apache Corp.

Joseph Thorp / Aramco Services Co.

Inlet Fogging and Overspray Impact on Gas Turbine Life and Performance

D R . K L A U S B R U NS O U T H W E S T R E S E A R C H I N S T I T U T E ®

D R . R A I N E R K U R ZS O L A R T U R B I N E S

M A RY B E T H N O R E DA P A C H E C O R P

J O S E P H T H O R PA R A M C O S E R V I C E S C O M P A N Y

INLET FOGGING AND OVERSPRAY IMPACT ON INDUSTRIAL GAS TURBINE

LIFE AND PERFORMANCE

BACKGROUND

• Twelve 12 GE5002CandDmodelsoperatedinmountainoustropicalclimatetodrivegasre‐injectioncompressors.

• Installationofinletfoggingandoverspraysystemswereintendedtoincreasepowerandefficiencyofthegasturbines.

• Initiallysomeperformanceincreasewasobservedbutarapiddecreaseinperformanceoccurredafterlessthan3 months onallunits.

• Onerotorwassenttooverhaulafter22,000hrs asdegradationexceeded10%.

• Visualrotorinspectionsshowedsignificantcompressorbladeleadingedgeerosion,tipclearanceopening,andcorrosionpitting.

Identifythecausesofperformancelossandbladedegradation.

STUDY OVERVIEW

• ReviewthefactorsthataffectperformanceofthegasturbinesandidentifytherootcauseofthecorrosionanderosioninGTcompressor:

• Performvisualbladeinspectionandgeometrymeasurementtoquantifybladeerosion.

• Collectbladefoulingdepositsandchemicallyanalyzethem

• Analyzeinletairfiltersamplesandwatersamplestoidentifysourcesofbladedeposits

• Performanalysisandteststodetermineimpactofinletcoolingandoversprayonperformance.

• Reviewoperationandmaintenancepractices:

• Inletcooling

• InletFiltration

• Water‐washing

ASIDE: INLET POWER AUGMENTATION BACKGROUND

InletAirChillers:Heatexchangercoolingofinletairusingmechanicalandabsorptionchillerswithorwithoutthermalenergystorage• Icehouses• Refrigerantcycles• Seawatercooling

EvaporativeCooling:Directreductionofinletairbywaterevaporation• Wettedmedia• Fogging• Wetcompression• Overspray• Interstage injection

GT INLET TEMPERATURE

INLET FOGGING

Gas Turbine

Drain

Pump SkidWater

Inlet Filter

- Up to 100% Relative Humidity – (Saturation) Fogging- Above 100% Relative Humidity – Overspray

Courtesy Mee Industries

EVAPORATIVE COOLING

Courtesy Mee Industries

Dry Bulb Thermometer

90°F32°C

70°F21°C

air

Wet Bulb Thermometer

Wet cloth wick

Evap. Cooling Potential

(20°F/11°C)

INLET COOLING

Psychiometric ChartDRY BULB TEMPERATURE (F)

80

40

40

60

Wet

Bulb (F

)

50

50

60

70

70

40%

80 90 100 120

20%

80%

60%

90

.004

.016

.012

.008

HU

MID

ITY R

ATIO

(Lbv/Lba)

.028

.024

.020

POWER AUGMENTATION (GE)

Courtesy General Electric

TYPICAL FOG NOZZLE ARRAY

TYPICAL SPRAY NOZZLES

Impact Pin

Orifice

Filter

SITE PUMP SKID INSTALLATION

Pump Skid with high-pressure pumps and Control Center

Pump Skid with high-pressure pumps and Control Center

High pressure feed lines (stainless steel

tubes).

High pressure feed lines (stainless steel

tubes).

SOME CONSIDERATIONS FOR INLET POWER AUGMENTATION

Concern Mitigation

Inleticing Temperatureshut‐off

FOD Inletscreen

Casingdistortion SprayPattern

Corrosion Waterquality

Erosion Droplet Size

Fouling Waterquality

Aerodynamicinstability Overspray,degradation

GE FRAME 5 DEGRADATION ANALYSIS(GE MS5002C/D)

RatedPower kW

HeatRatekJ/kWh

Efficiency%

PressureRatio

ExhaustFlowkg/sec

TurbineSpeedRPM

ExhaustTemperature

°C20,340 12,470 28.8 8.8 123.4 4760 517

COMPRESSOR IMPACT ON GT PERFORMANCE

Fouling Performance Loss

0

2

4

6

8

10

12

0 1 2 3 4 5 6 7

% Compressor Ratio Decrease

% G

T Pe

rform

ance

Dec

reas

e

Power Efficiency

COMPRESSOR DEGRADATION MECHANISMS

• Fouling:Thedepositionofparticlesonblades

• SurfaceCorrosion:Surfaceoxidationandmateriallossofblades

• LE/TEErosion:Abrasiveremovalofmaterialofbladeleadingandtrailingedge

• TipClearances:Openingofbladetipclearancescausedbyrubbinganderosion

Allnegativelyaffectaerodynamicperformanceofcompressor.

Assembled Rotor that was Analyzed

TYPICAL COMPRESSOR DEGRADATION AGENTS

Type Cause EffectSand FilterOpenings ErosionDirt/fines Filter/saturation FoulingCarbon/oil ExhaustFumes FoulingSalt AtmosphericSalt

OceanCorrosion

Salt Waterinjection CorrosionSulfur Exhaust Fumes,

AtmosphereCorrosion

Calcium Waterinjection Fouling

COMPRESSOR DEGRADATION STUDY (22K HRS ROTOR)

BLADE VISUAL EXAMINATION

Row 0:

Severe erosion on leading edge

Row 5: Shallow

pitting/ erosion on

suction side near leading

edge

Row 10:

Pitting on suction side near trailing edge

Row 15:

Significant patches of

pitting throughout

BLADE DEPOSIT CHEMICAL ANALYSIS

Compressor Deposits in Row #1: Sand/Dirt

Compressor Deposits in Row #4: Carbon/Oils

BLADE DEPOSIT CHEMICAL ANALYSIS

Compressor Deposits in Row #11:Salt

Compressor Deposits in Row #16: Salt/Sulfur

BLADE SURFACE CHEMISTRY

Sodium Concentration Found in Deposit Analisys of Frame 5 Rotor at Different Rows

0

5

10

15

20

25

30

35

40

Row

1

Row

4

Row

11

Row

16

Con

cent

ratio

n pe

rcen

tage

(%)

Sodium Concentration

Concentration of Sodium in Different Compressor Rows

SALT FOULING REDEPOSIT

•

•

•

•

TESTED WATER QUALITY(FROM “TREATMENT” PLANT)

Average Chlorides Concetration of the Water Used for Fogging

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Jul-0

2S

ep-0

2N

ov-0

2Ja

n-03

Mar

-03

May

-03

Jul-0

3S

ep-0

3N

ov-0

3Ja

n-04

Mar

-04

May

-04

Jul-0

4S

ep-0

4N

ov-0

4Ja

n-05

Mar

-05

May

-05

Jul-0

5S

ep-0

5N

ov-0

5Ja

n-06

Mar

-06

May

-06

Jul-0

6S

ep-0

6N

ov-0

6

Con

cetr

atio

n(m

g/L)

Average Concentration of Chlorides Getting into the Axial Compressor of the MS-5002C Units

0

200

400

600

800

1000

1200

1400

Fall

03

Win

ter 0

3

Sprin

g 04

Sum

mer

04

Fall

04

Win

ter 0

4

Sprin

g 05

Sum

mer

05

Fall

05

Win

ter 0

5

Sprin

g 06

Sum

mer

06

Fall

06

Win

ter 0

6

Chl

orid

es (g

/mon

th)

Average Chloride Concentration of Water for Fogging

0.5‐1.5kgofSaltperMonth

BLADE EXAMINATION SUMMARY FINDINGS

•

•

•

•

BLADE FOULING, EROSION, AND CORROSION MECHANISMS

• Salts• Salts andotherchlorides incombinationwithmoistureareprimarilyresponsibleformetalsurfacepittingingasturbinecompressor

• OilsandWaxes• Oilsandwaxesareresiduesfromcompressorwashingorambientaircontamination

• Formaverythinsurfacefilmontheblades• Oilsandwaxesactasbindingagentsfordirtorsand

• Carbon• Carbon orCoke depositsoncompressorbladesindicatethatexhaustgasesfromthegasturbineorotherinternalcombustionenginesareenteringtheaxialcompressor

• Dirt Sands• Sandisasignificantcontributortobladeleadingandtrailingedgeerosionandsurfacefouling

• Introducedintothegasturbinethroughtheinletfilterandisanindicationofinadequateinletfiltrationorfilterdirtsaturation

• CorrosiveAgents• Foreigncorrosiveagents,suchassulfurcompounds,vanadium,orheavymetalsareintroducedbypollutantsintheambientair

ASIDE: COMPRESSOR WASHINGCONSIDERATIONS

•

•

•

•

•

INLET FILTRATION

•

••

•

INLET FILTER CONSIDERATIONS

API Limit

INLET FILTER CONDITION

• Pressuretestingandvisualobservationofthefiltersindicatedfilterdirtsaturation.

• Chemicalanalysisoffiltersalsoshowedsaltpenetration.

Site 1 Filter Sample Site 2 Filter Sample

FILTER DIRT SATURATIONS PROCESS

•

•

•

•

INLET AIR FILTER DP TRENDING

Average Differential Pressure Through Inlet Air Filter and Process Gas vs. Time for HP3 Unit

1.0

10.0

100.0

1000.0

May

-200

3

Jul-2

003

Sep-

2003

Nov

-200

3

Jan-

2004

Mar

-200

4

May

-200

4

Jul-2

004

Sep-

2004

Nov

-200

4

Jan-

2005

Mar

-200

5

May

-200

5

Jul-2

005

Sep-

2005

Nov

-200

5

Diff

eren

tial P

ress

ure

Thro

ugh

Inle

tA

ir Fi

lters

(H20

) and

Pro

cess

Gas DP (in-H2O) Process Gas

MMCSFD

INLET DP: PROBLEM IDENTIFICATION

Trend CauseSuddenlyincreasingfilterdP Dustsaturation,water

SuddenlydecreasingfilterdP Filterbreak,inletducthole,blow‐in door

SlowlyincreasingFilterdP Probably normalSlowlydecreasingdP Flexiblejointripping,sensor

drift,filter breakCyclicaldP Filtersaturation/water

SUMMARY OF INSPECTION AND TEST OBSERVATIONS

• RapidLE/TEedgeandtiperosionofthecompressorbladesisattributedtoover‐spraying.

• Foggingwaterhasdissolvedsaltsorotherchloridesleadingtofoulingandcorrosionpitting.

• Gasturbineisingestingexhaustfromothercombustionmachines

• On‐lineandoff‐linewashingmethodsarenotadequatefortheapplicationandcausere‐depositsinlaststagesofcompressor.

• Theinletfiltershaveinadequaterainprotectionresultingindirtsaturationandcarry‐over.

PREDICTED PERFORMANCE:POWER AUGMENTATION

Average Turbine Power Output ComparisionMS-5002 C Units at Cusiana

34500

35000

35500

36000

36500

37000

Fall

03

Win

ter 0

3

Sprin

g 04

Sum

mer

04

Fall

04

Win

ter 0

4

Sprin

g 05

Sum

mer

05

Fall

05

Win

ter 0

5

Sprin

g 06

Sum

mer

06

Fall

06

Win

ter 0

6

Pow

er (H

P)

Turbine Power Output with Fogging Overspray Turbine Power Output without Fogging Turbine Power Output with Fogging

PREDICTED PERFORMANCE:EFFICIENCY

Turbine Efficiency vs. SeasonMS-5002 C Units at Cupiagua

28.228.328.428.528.628.728.828.929.029.129.2

Fall

03

Win

ter 0

3

Spr

ing

04

Sum

mer

04

Fall

04

Win

ter 0

4

Spr

ing

05

Sum

mer

05

Fall

05

Win

ter 0

5

Spr

ing

06

Sum

mer

06

Fall

06

Win

ter 0

6

Effic

ienc

y (%

)

Efficiency With Fogging Overspray Efficiency Without FoggingEfficiency With Fogging

PREDICTED PERFORMANCE:FOGGING EFFICIENCY INCREASE

Increase of Turbine Efficiency due to FoggingFrame 5

0.000.501.001.502.002.503.003.504.004.505.00

Fall

03

Win

ter 0

3

Sprin

g 04

Sum

mer

04

Fall

04

Win

ter 0

4

Sprin

g 05

Sum

mer

05

Fall

05

Win

ter 0

5

Sprin

g 06

Sum

mer

06

Fall

06

Win

ter 0

6

Incr

ease

of E

ffci

ency

(%)

ACTUAL PERFORMANCE (AT 22K HRS):CALCULATED LOSSES BY SOURCE

Relative Influence

Power Loss (HP)

Blade Surface Fouling

10% 360

Surface Corrosion/Pitting

15% 540

Blade Edge Erosion 35% 1,260

Rotor Clearances 30% 1,080System Losses 10% 360

Recoverable Some Recovery Not Recoverable

NON-RECOVERABLE DEGRADATION RATE

Average Gas Turbine Power Output vs. Time

33000

33500

34000

34500

35000

35500

36000

36500

0

1000

0

2000

0

3000

0

4000

0

5000

0

6000

0

Operating Time (Hour)

Ave

rage

Tur

bine

Pow

er O

utpu

t (h

p)

Ideal Power With FoggingIdeal Power Without FoggingForecasted Power Degradation With Fogging

2233

0

Overspray

Normal

CrossOver

CrossOver

Fogging

Blade Degradation

0123456789

101112131415

0 0.5 1 1.5 2 2.5 3

Equivalent Chord Loss

% S

urge

Mar

gin

Surge Margin versus Blade Degradation

Equivalent Chord Loss Includes Aerodynamic Degradation

Surge Margin

Safety Surge Margin

COMPRESSOR DEGRADATION AERO-STABILITY

COMPRESSOR FOGGING & OVERSPRAY AERO-STABILITY

Interstage Injection

0123456789

101112131415

0 10 20 30 40 50 60 70 80 90 100

% Saturation

% S

urge

Mar

gin

Stage 1

Stage 2

Stage 1 and 2

SUMMARY AND CONCLUSIONS

•

•

•

SUMMARY AND CONCLUSIONS

•

•

•

SUMMARY AND CONCLUSIONS

•

•

SUMMARY AND CONCLUSIONS

•

SUMMARY AND CONCLUSIONS

•

SUMMARY AND CONCLUSIONS

•

SUMMARY AND CONCLUSIONS

•

Thank you very much.

Questions, please.