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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
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
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
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
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 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
INLET FILTER CONDITION
• Pressuretestingandvisualobservationofthefiltersindicatedfilterdirtsaturation.
• Chemicalanalysisoffiltersalsoshowedsaltpenetration.
Site 1 Filter Sample Site 2 Filter Sample
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
Recommended