gas turbine 4
TRANSCRIPT
External Services (Gas Turbines)
1HDGT.PPT/
Heavy-Duty Gas Turbine Operating and Maintenance Considerations
External Services (Gas Turbines)
2HDGT.PPT/
A Maintenance Program should:
Optimize owner’s maintenance costs
Maximize equipment availability
External Services (Gas Turbines)
3HDGT.PPT/
Case 2
1,000 Hrs/Yr400 Starts/Yr
HGP at 3 years, not 24 years
Case 1
8,000 Hrs/Yr160 Starts/Yr
HGP at 3 years
Because not all customers operate their gas turbines the same,
not all customer maintenance programs are the same.
BHEL Provides Guidance for Customer Maintenance Planning
External Services (Gas Turbines)
4HDGT.PPT/
Factors Affecting Maintenance Planning and Maintenance Program
MaintenanceProgram
MaintenanceProgram
ManufacturersRecommendedMaintenance
Program
ManufacturersRecommendedMaintenance
Program
DiagnosticsDiagnostics
AvailabilityNeed
AvailabilityNeed
On-SiteMaintenance
Capability
On-SiteMaintenance
Capability
DesignFeaturesDesign
Features
UtilizationNeed
UtilizationNeed
DutyCycleDutyCycle
EnvironmentEnvironment
Cost ofDowntimeCost of
Downtime
Type ofFuel
Type ofFuel
ExpertSystems
ExpertSystems
ReserveRequirements
ReserveRequirements
External Services (Gas Turbines)
5HDGT.PPT/
Potential Failure Modes
Continuous Duty Application– Creep Deflection– Creep Rupture– Corrosion– Oxidation– Erosion– High-Cycle Fatigue
Hot-Gas-Path Components
Cyclic Duty Application– Themal Mechanical
Fatigue– Rubs/Wears
External Services (Gas Turbines)
6HDGT.PPT/
GE Bases Gas Turbine Maintenance Requirements on Independent Counts of Starts & Hours
Fatigue Limits Life
Failure Region
DifferentMechanismLimit Life
OxidationCreep,
Corrosion& Wear
Limit Life
DesignLife
HoursGE Inspection
Recommendation
CompetitionInspection
Recommendation(Equivalent Hours Per Start)
GE InspectionRecommendation
StartsDesign
Life
External Services (Gas Turbines)
7HDGT.PPT/
GE vs. Equivalent Hours Approach
0
200
400
600
800
1000
1200
0 4 8 12 16 20 24 28
EOH METHOD
GEMETHOD
Case 24000 Hrs/Yr300 Starts/YrGE Every 4 YrsEOH Every 2.4 Yrs
Case 18,000 Hrs/Yr160 Starts/YrGE Every 3 YrsEOH Every 2.1 Yrs
Fired Hours (x1000)
Starts
External Services (Gas Turbines)
8HDGT.PPT/
Maintenance Cost and Equipment Life Are Influenced by Key Service Factors
Fuel
Firing Temperature
Steam/Water Injection
Cyclic Effects (Start-up rate, number of trips)
Air Quality
Service Factors Different From the Reference ConditionService Factors Different From the Reference Condition**Can Increase Maintenence Cost & Reduce Maintenence IntervalsCan Increase Maintenence Cost & Reduce Maintenence Intervals
Service Factors Different From the Reference ConditionService Factors Different From the Reference Condition**Can Increase Maintenence Cost & Reduce Maintenence IntervalsCan Increase Maintenence Cost & Reduce Maintenence Intervals
External Services (Gas Turbines)
9HDGT.PPT/
Maintenance FactorsHot Gas Path (Buckets & Nozzles)
Typical Max Inspection Intervals (MS6B/Ms7EA)Hot Gas Inspection 24,000 hrs or 1200 StartsMajor Inspection 48,000 hrs or 2400 Starts
Criterion is Hours or Starts (Whichever Occurs First)
Hours Factors
FuelGas 1Distillate 1.5Crude 2 to 3Residual 3 to 4
Peak Load 6 Water/Steam Injection
Dry Control 1 (GTD-222)Wet Control 1.9 (5% H20)
Factors Impacting Maintenance
Starts Factors
Trip From Full Load 8 Fast Load 2 Emergency Start 20
External Services (Gas Turbines)
10HDGT.PPT/
Maintenance Factors Reduce Maintenance Interval
0
200
400
600
800
1000
1200
1400
0 4 8 12 16 20 24 28
Starts FactorsTrips, Fast Starts
Hours Factors• Firing Temp• Steam/H2O Injection•Fuel Type
Fired Hours (x1000)
Starts
External Services (Gas Turbines)
11HDGT.PPT/
Estimated Effect of Fuel Type on Maintenance
Residual
MaintenanceFactor
Distillates
HeavyLight
Natural Gas
7 8 9 10 11 12 13 14 15
Fuel Percent Hydrogen by Weight in Fuel
20
External Services (Gas Turbines)
12HDGT.PPT/
Hot Corrosion
Life
Oxidation is Limiting Factor
Corrosion becomes Limiting Factor
Na Concentration in Combustion Products
Component surface saturated with condensated corrosive deposits. Life limited primarily by kinetics of thecorrosion reaction.
External Services (Gas Turbines)
13HDGT.PPT/
Life Factor
Change in firing temperature - degrees F
Peak rating ofTf + 100 F (65 C) has life factor of 6
Bucket Life Firing Temperature Effect
(MS6001B/MS7001EA/MS9001E)
(MS5001P Uncooled bucket)
0.01
0.1
1
10
100
-200 -100 0 100 200
External Services (Gas Turbines)
14HDGT.PPT/
Example 1:
A unit which has operated at Peak Load (+100 F) for 100 hours would have to be operated at - 50 F for 833 hours to maintain a maintenance factor of ONE.
MF =
833 hrs (0.4) + 100 hrs (6.0)
(833 + 100) hrs=
Factored HoursActual Hours
= 1
External Services (Gas Turbines)
15HDGT.PPT/
Example 2:
Determine the Maintenance Factor for a unit which operates at Base Load for 6000 hours, Peak Load for 600 hours, and at -50 F Firing Temperature for 15000 hours.
MF =
6000 hrs (1.0) + 500 hrs (6.0) + 1500 hrs (0.4)
(6000 + 1500 + 500) hrs=
Factored HoursActual Hours
MF = 1.2
External Services (Gas Turbines)
16HDGT.PPT/
1000
1500
2000
2500
20 40 60 80 100 120
Firing Temp.
Fo
% Load
57 VIGV
84 VIGV
Close IGVs 84 to 57 deg
Tf constant @2020 F
o
o
Close IGVs 84 to 57 deg
Tx constant @ 700 deg F
Heat Recovery
Simple Cycle
Firing Temperature and Load
Heat Recovery vs Simple Cycle
External Services (Gas Turbines)
17HDGT.PPT/
1
10
-200 -150 -100 -50 0 50
5
Maximum Heavy FuelFiring Temperature
Delta Firing Temperature Fo
Maintenance Factor Residual
Crude
Heavy Fuel Maintenance Factors(MS6001B/7001EA/9001E)
2
External Services (Gas Turbines)
18HDGT.PPT/
Steam/Water Injection and Nozzle Creep Deflection
3rd StageNozzle
2nd StageNozzle
Steam/Water Injection Impacts Stage 2/3 Nozzle Maintenanceand Life
Increases Nozzle Gas Loads
Increases Downstream Deflection Rate
Decreases Maintenance Interval
GTD-222 Nozzle Alloy MinimizesThis Effect
External Services (Gas Turbines)
19HDGT.PPT/
Steam/Water Injection Increases Metal Temperature of
Hot-Gas-Path Components
Steam/Water Injection and Bucket/Nozzle Life
• Water Effects Gas Transport Properties:- Thermal Conductivity increases- Specific Heat increases- Viscosity remains steady
• This increases Heat Transfer Coefficients which increases metal temperature and decreases bucket life
Example (MS7001EA Stage 1 Bucket):3% Steam increaes bucket metal temperature 15 F and decreases Life -33%at constant firing temperature
External Services (Gas Turbines)
20HDGT.PPT/
0
10
20
30
40
50
Dry Control
Wet Control 3% Steam Inj.TF = 2020 F
Load Ratio = 1.10
3 % Steam Inj.TF = 1994 F
Load Ratio = 1.08
Exhaust Temperature
F
Compressor Discharge Pressure (psig)
0% Steam Inj. TF = 2020 F
Load Ratio = 1.0
Exhaust Temperature Control CurveDry Versus Wet Control
Steam Injection for 25 ppm NOX
o
o
o
o
External Services (Gas Turbines)
21HDGT.PPT/
Maintenance Factors Reduce Maintenance Interval
0
200
400
600
800
1000
1200
1400
0 4 8 12 16 20 24 28
Starts FactorsTrips, Fast Starts
Hours Factors• Firing Temp• Steam/H2O Injection•Fuel Type
Fired Hours (x1000)
Starts
External Services (Gas Turbines)
22HDGT.PPT/
Exh.Temp.
TimeStart-up Shutdown
Light-offAcceleration
Warm-up
Full SpeedNo Load
Full SpeedNo Load
Load Ramp
Base Load
Fired Shutdown
Trip
Unload Ramp
Turbine Start/Stop Cycle
External Services (Gas Turbines)
23HDGT.PPT/
% Load
Mai
nt.
Fac
tor
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 20 40 60 80 100 120
Effect of Start Cycle Max Load Level
External Services (Gas Turbines)
24HDGT.PPT/
Low Cycle Fatigue Life Sensitivities First-Stage Bucket
Normal Startup/Shutdown Normal Start & Trip
1 Trip Cycle = 8 Normal Shutdown Cycle
+
-
+
-
Strain- %
Strain- %Temperature Temperature
TMAXTMAX
Leading Edge Temperature/Strain
External Services (Gas Turbines)
25HDGT.PPT/
% Load
Trip
Sev
erit
y F
acto
r
0123456789
10
0 20 40 60 80 100 120
Base
FSNL
For trips during Start-upAcceleration, assume Trip Severity Factor = 2
Maintenance Factor - Trips from Load
External Services (Gas Turbines)
26HDGT.PPT/
Heavy-Duty Gas Turbine
Combustion
Hot-Gas-Path
Major
Shutdown Inspections Major inspectionHot-Gas-Path
Inspection
CombustionInspection
External Services (Gas Turbines)
27HDGT.PPT/
CombustorDesign
NOx
EmissionsLevel (ppm) Diluent
Fuel
GasHours/Starts
DistillateHours/Starts
Dry
Steam
Water
Steam
Water
Standard Liner
65
42
8,000/800
----
----
8,000/400
6,500/300
8,000/800
8,000/400
6,500/300
3,000/150
1,500/100
MS7001EA Combustion Inspection Intervals
Extendor Combustion System Wear Kit IncreasesCombustion Inspection to as Much as 24,000 Hours
External Services (Gas Turbines)
28HDGT.PPT/
Base Line Recommended Inspection Intervals Base Load - Gas Fuel - Dry
Factors That Can Reduce Maintenance Intervals
Fuel
Load Setting
Steam/Water Injection
Peak Load Tf Operation
Trips from Load Start Cycle HGP Hardware Design
Type ofInspection
Combustion
Hot-Gas Path
Major
Hours/Starts
12000/800
MS32/52/51 Upgrade
Eliminated/1200
4800/2400
8000/800
24000/900
48000/2400
12000/800
24000/1200
48000/2400
MS6B MS7E/EAMS9E/7FA/
9FA
8000/800
24000/1200
48000/2400
External Services (Gas Turbines)
29HDGT.PPT/
Maintenance Factor Definition
IDEAL INTERVAL = Interval for Continuous Base Load on Clean Natural Gas
RECOMMENDED INTERVAL = Ideal Interval determined from
application of maintenance factors
External Services (Gas Turbines)
30HDGT.PPT/
N2 / N3 Material
GTD-222 / FSX-414GTD-222FSX-414
GTD-222 / FSX-414
HGPI Hours Based CriterionMS6001/7001/9001
Maintenance Interval(Hours)
=24000
Maintenance FactorWhere:
Maintenance Factor = Factored Hours
Acutal Hours
Factored Hours = (K + (M x I)) x (G + 1.5 D + Af H + 6 P)
Actual Hours = (G + D + H + P)G = Operating Hours on Gas FuelD = Operating Hours on Distillate FuelH = Operating Hours on Heavy Fuel
Af = Heavy Fuel Severity Factor (Residual Af = 3 to 4, Crude Af = 2 to 3)
P = Peak Load Operating HoursI = Percent Water/Steam Injection Referenced to Inlet Air FlowM & K = Water/Steam Injection Constants
M
00
.18
.18
K
11.61
Control
DryDryDryWet
Steam Injection
< 2.2 %> 2.2 %> 2.2 %> 0 %
External Services (Gas Turbines)
31HDGT.PPT/
S = Maximum Starts-Based Maintenance Interval (Model Size Dependent)NA = Number of Part Load Start/Stop Cycles (< 60% Load)NB = Number of Normal Base Load Start/Stop CyclesNP = Number of Peak Load Start/Stop CyclesE = Number of Emergency StartsF = Number of Fast Load Starts
Tn = Trips
aT n = Trip Severity Factor
n = Trip number
S
1,2001,200900900
HGPI Starts Based CriterionMS6001/7001/9001 Maintenance Interval
(Starts)=
S
Maintenance FactorWhere:
Maintenance Factor = Factored Starts
Acutal Starts
Factored Starts = (0.5 NA + NB + 1.3 NP + 20 E + 2 F +
Actual Starts = (NA + NB + NP + E + F)
Model Series
MS6B/MS7EAMS6FAMS9E
MS7F/7FA/9F/9FA
aTi Ti )
n
i = 1
External Services (Gas Turbines)
32HDGT.PPT/
First-Stage Nozzle Wear - Preventive MaintenanceGas-Fired - Continuous Duty - Base Load
NozzleCondition
New Nozzle Acceptance Standards
Repaired NozzleMin. AcceptanceStandard
1st Repair
2ndRepair 3rd
Repair
Severe Deterioration
Repair CostExceedsReplacementCost
WithoutRepair
Operating Hours
10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000
External Services (Gas Turbines)
33HDGT.PPT/
Combustion LinersTransition PiecesFuel NozzlesCross-Fire Tubes1st Stage Nozzles2nd Stage Nozzles3rd Stage Nozzles1st Stage Buckets
2nd Stage Buckets3rd Stage Buckets1st Stage Shrouds2nd/3rd Stage Shrouds
CICICICI
HGPIHGPIHGPIHGPI*
HGPIHGPIHGPIHGPI
5 (CI)6 (CI)3 (CI)3 (CI)
3 (HGPI)3 (HGPI)3 (HGPI)2 (HGPI)
3 (HGPI)**3 (HGPI)3 (HGPI)2 (HGPI)3 (HGPI)
5 (CI)6 (CI)3 (CI)3 (CI)
3 (HGPI)3 (HGPI)3 (HGPI)3 (HGPI)
4 (HGPI)4 (HGPI)2 (HGPI)4 (HGPI)
RepairInterval
Replace Interval(Hours)
ReplaceInterval(Starts)
CI = Combustion Inspection IntervalHGPI = Hot Gas Path Inspection Interval* When recoating, perform after one hours-based HGPI** Two HGPI without recoat, Three HGPI with Recoat
Estimated Repair & Replacement
External Services (Gas Turbines)
34HDGT.PPT/
Maintenance Factors Summary
Maintenance Requirements are Based on an Independent Count of Hours and Starts
Certain Operating Factors Reduce Maintenance Intervals Peak Loac Steam/Water Injection >2.2% Liquid Fuel Trips From Load Fast Starts
Exceeding GE Specification Limits can Significantly Increase Maintenance Factors and Reduce Component Life
Equations for Establishing Application Specific Hot Gas Path Maintenance Intervals are Available
External Services (Gas Turbines)
35HDGT.PPT/
Bucket Life Firing Temperature EffectMS6001B / MS7001EA / MS9001E
100
LifeFactor
1
10
0 50 100 150 200 250
0 25 50 75 100 125
Peak Rating+100°F (56C) T.Life Factor -6
C
Change inFiring
Temperature
External Services (Gas Turbines)
36HDGT.PPT/
Operating Inspection Data ParametersSpeed
Load
Fired Starts
Fired Hours
Site Barometric Reading
Temperatures
Inlet Ambient
Compressor Discharge
Turbine Exhaust
Turbine Wheelspace
Lube Oil Header
Lube Oil Tank
Bearing Drains
Exhaust Spread
Pressures
– Compressor Discharge
– Lube Pump(s)
– Bearing Header
– Cooling Water
– Fuel
– Filters (Fuel, Lube, Inlet Air) Vibration Data for Power Train Generator
– Output Voltage
– Phase Current
– VARS
– Load Start-Up Time Coast-Down Time
– Field Voltage
– Field Current
– Stator Temp.
– Vibration
External Services (Gas Turbines)
37HDGT.PPT/
Deterioration of Gas Turbine Performance Due to Compressor Blade Fouling
8
6
4
2
0
-2
-4
-6
-8
-10
-12
-14
Heat RateIncrease
%
OutputDecrease
%
-1 -2 -3 -4 -5 -6 -7 -8
5% Loss ofAirflow
Fouling
Fouling
Pressure Ratio Decrease - %
External Services (Gas Turbines)
38HDGT.PPT/
Maintenance Inspections Hot Gas Path Inspection - Key Elements
Foreign Objects Damage
Oxidation/Corrosion/Erosion
Cracking
Cooling Hole Plugging
Remaining Coating Life
Nozzle Deflection/Distortion
Abnormal Deflection/Distortion
Abnormal Wear
Missing Hardware
Clearance Limits
Potential Actions:Potential Actions:Potential Actions:Potential Actions:Inspect for:Inspect for:Inspect for:Inspect for:Key HardwareKey HardwareKey HardwareKey Hardware
Nozzles (1,2,3)
Buckets (1,2,3)
Stator Shrouds
IGV’s & Bushings
Compressor Blading(Borescope)
Repair/Refurbishment Nozzles
Weld RepairRepositionRecoat
BucketsStrip & RecoatWeld RepairBlend
Criteria:Criteria: Op. & Instr. ManualOp. & Instr. Manual TIL’sTIL’s Field EngineersField Engineers
Inspection Inspection Methods:Methods:
VisualVisual LPLP BoroscopeBoroscope
Combustion Inspection Work Scope – Plus:Combustion Inspection Work Scope – Plus:
Availability of On SiteAvailability of On SiteSpares Is Key to Spares Is Key to
Minimizing DowntimeMinimizing Downtime
External Services (Gas Turbines)
39HDGT.PPT/
Maintenance Inspections Combustion Inspection - Key Elements
Foreign Objects Abnormal Wear Cracking Liner Cooling Hole Plugging TBC Coating Condition Oxidation/Corrosion/Erosion Hot Spots/Burning Missing Hardware Clearance Limits Borescope Compressor and
Turbine
Potential Actions:Potential Actions:Potential Actions:Potential Actions:Inspect for:Inspect for:Inspect for:Inspect for:Key HardwareKey HardwareKey HardwareKey Hardware
Combustion Liners
Combustion Covers
Fuel Nozzles
Transition Pieces
Cross Fire Tubes
Flow Sleeves
Check Valves
Spark Plugs
Flame Detectors
Flex Hoses
Repair/Refurbishment Liners
Cracking/Erosion/Wear
TBC Repair Transition Pieces
WearTBC RepairDistortion
Fuel NozzlesPluggingErosion/Wear
Cross Fire TubesWear/Burning
Criteria:Criteria: Op. & Instr. ManualOp. & Instr. Manual TIL’sTIL’s Field EngineersField Engineers
Inspection Inspection Methods:Methods:
VisualVisual LPLP BoroscopeBoroscope
Availability of On SiteAvailability of On SiteSpares Is Key to Spares Is Key to
Minimizing DowntimeMinimizing Downtime
External Services (Gas Turbines)
40HDGT.PPT/
Maintenance Inspections GT Major Inspection - Key Elements
Foreign Objects Damage Oxidation/Corrosion/Erosion Cracking Leaks Abnormal Wear Missing Hardware Clearance Limits
Potential Actions:Potential Actions:Potential Actions:Potential Actions:Inspect for:Inspect for:Inspect for:Inspect for:Key HardwareKey HardwareKey HardwareKey Hardware
Compressor Blading
Turbine Wheels Dovetails
Journal and Seal Surfaces
Bearing Seals
Inlet System
Exhaust System
Repair/Refurbishment Stator Shrouds
Oxidation/Corrosion/Erosion
BucketsCoating DeteriorationFOD/Rubs/CrackingTip Shroud DeflectionCreep Life Limit
NozzlesSevere Deterioration
IGV BushingsWear
Bearings/SealsBooring/Wear
Compressor BladesCorrosion/ErosionRubs/FOD
Criteria:Criteria: Op. & Instr. ManualOp. & Instr. Manual TIL’sTIL’s Field EngineersField Engineers
Inspection Inspection Methods:Methods:
VisualVisual LPLP BorescopeBorescope
Combustion Inspection Work Scope Combustion Inspection Work Scope Hot–Gas Path Inspection Work Scope – PlusHot–Gas Path Inspection Work Scope – Plus