gt maintanance

8/10/2019 Gt Maintanance

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External Servic es (Gas Turbin es

1HDGT.PPT/

Heavy-Duty GasTurbine Operatingand MaintenanceConsiderations


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2HDGT.PPT/

A Maintenance Program should:

Optimize owners maintenance costs

Maximize equipment availability


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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


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4HDGT.PPT/

Factors Affecting Maintenance Planning and

Maintenance Program

Maintenance

Program

ManufacturersRecommendedMaintenance

Program

Diagnostics

Availability

Need

On-Site

Maintenance

Capability

DesignFeatures

Utilization

Need

DutyCycle

Environment

Cost ofDowntime

Type of

Fuel

Expert

Systems

Reserve

Requirements


5/40


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


6/40


6HDGT.PPT/

GE Bases Gas Turbine MaintenanceRequirements on Independent Counts ofStarts & Hours

Fatigue Limits Life

Failure Region

Different

Mechanism

Limit Life

Oxidation

Creep,

Corrosion

& WearLimit Life

Design

Life

Hours

GE InspectionRecommendation

Competition

Inspection

Recommendation

(Equivalent Hours Per Start)

GE Inspection

Recommendation

StartsDesign

Life


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7HDGT.PPT/

GE vs. Equivalent Hours Approach

0

200

400

600

800

1000

1200

0 4 8 12 16 20 24 28

EOH

METHOD

GE

METHOD

Case 2

4000 Hrs/Yr

300 Starts/Yr

GE Every 4 Yrs

EOH Every 2.4 Yrs

Case 1

8,000 Hrs/Yr

160 Starts/Yr

GE Every 3 Yrs

EOH Every 2.1 Yrs

Fired Hours (x1000)

Starts


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8HDGT.PPT/

Maintenance Cost and Equipment LifeAre Influenced by Key Service Factors

Fuel

Firing Temperature

Steam/Water InjectionCyclic Effects (Start-up rate, number of trips)

Air Quality

Service Factors Different From the Reference Condition*

Can Increase Maintenence Cost & Reduce Maintenence Intervals


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9HDGT.PPT/

Maintenance Factors

Hot Gas Path (Buckets & Nozzles)

Typical Max Inspection Intervals (MS6B/Ms7EA)

Hot Gas Inspection 24,000 hrs or 1200 Starts

Major Inspection 48,000 hrs or 2400 Starts

Criterion is Hours or Starts (Whichever Occurs First)

Hours Factors

FuelGas 1

Distillate 1.5

Crude 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


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1HDGT.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

InjectionFuel Type

Fired Hours (x1000)

Starts


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1HDGT.PPT/

Estimated Effect of Fuel Type on Maintenance

Residual

Maintenance

Factor

Distillates

HeavyLight

Natural Gas

7 8 9 10 11 12 13 14 15

Fuel Percent Hydrogen by Weight in Fuel

20

E t l S i (G T bi


12/40


1HDGT.PPT/

Hot Corrosion

Life

Oxidation

is

Limiting

FactorCorrosion becomes

Limiting Factor

Na Concentration in Combustion Products

Component surface saturated

with condensated corrosive deposits.

Life limited primarily by kinetics of the

corrosion reaction.

E t l S i (G T bi


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1HDGT.PPT/

Life

Factor

Change in firing temperature - degrees F

Peak rating of

Tf + 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

E t l S i (G T bi


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1HDGT.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 Hours

Actual Hours

= 1

E ternal Ser ic es (Gas T rbin es


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1HDGT.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 Hours

Actual Hours

MF = 1.2



16/40


1HDGT.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 IGVs84 to 57 deg

Tx constant @ 700 deg F

Heat Recovery

Simple Cycle

Firing Temperature and Load

Heat Recovery vs Simple Cycle



17/40


1HDGT.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



18/40


1HDGT.PPT/

Steam/Water Injection and Nozzle

Creep Deflection

3rd Stage

Nozzle

2nd Stage

Nozzle

Steam/Water Injection Impacts

Stage 2/3 Nozzle Maintenance

and Life

Increases Nozzle Gas Loads

Increases Downstream

Deflection Rate

Decreases Maintenance

Interval

GTD-222 Nozzle Alloy Minimizes

This Effect



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1HDGT.PPT/

Steam/Water Injection Increases Metal Temperatureof

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



20/40


2HDGT.PPT/

0

10

20

30

40

50

Dry Control

Wet Control 3% Steam Inj.

TF= 2020 FLoad Ratio = 1.10

3 % Steam Inj.TF= 1994 F

Load Ratio = 1.08

ExhaustTemperature

F

Compressor Discharge Pressure (psig)

0% Steam Inj.

TF= 2020 FLoad Ratio = 1.0

Exhaust Temperature Control Curve

Dry Versus Wet Control

Steam Injection for 25 ppm NOX

o

o

o

o



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2HDGT.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



22/40


2HDGT.PPT/

Exh.

Temp.

TimeStart-up Shutdown

Light-offAcceleration

Warm-up

Full SpeedNo Load

Full Speed

No Load

Load Ramp

Base Load

Fired Shutdown

Trip

Unload Ramp

Turbine Start/Stop Cycle


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25/40

(

2HDGT.PPT/

% Load

TripSeverityFa

ctor

01

2

3

4

5

67

8

9

10

0 20 40 60 80 100 120

Base

FSNL

For trips during Start-up

Acceleration, assume

Trip Severity Factor = 2

Maintenance Factor - Trips from Load



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(

2HDGT.PPT/

Heavy-Duty Gas Turbine

Combustion

Hot-Gas-Path

Major

Shu tdown Insp ect ionsMajor inspection

Hot-Gas-PathInspection

CombustionInspection



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(

2HDGT.PPT/

Combustor

Design

NOxEmissions

Level (ppm) Diluent

Fuel

Gas

Hours/StartsDistillate

Hours/Starts

Dry

Steam

Water

Steam

Water

Standard

Liner65

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 Increases

Combustion Inspection to as Much as 24,000 Hours


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2HDGT.PPT/

Maintenance Factor Definition

IDEAL INTERVAL = Interval for Continuous Base Loadon Clean Natural Gas

RECOMMENDED

INTERVAL = Ideal Interval determined fromapplication of maintenance factors



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3HDGT.PPT/

N2 / N3 Material

GTD-222 / FSX-414

GTD-222

FSX-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 + AfH + 6 P)Actual Hours = (G + D + H + P)

G = Operating Hours on Gas Fuel

D = Operating Hours on Distillate Fuel

H = Operating Hours on Heavy Fuel

Af = Heavy Fuel Severity Factor (Residual Af = 3 to 4, Crude Af = 2 to 3)

P = Peak Load Operating Hours

I = Percent Water/Steam Injection Referenced to Inlet Air Flow

M & K = Water/Steam Injection Constants

M

0

0

.18

.18

K

1

1

.6

1

Control

Dry

Dry

Dry

Wet

Steam Injection

< 2.2 %

> 2.2 %

> 2.2 %

> 0 %


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32/40

3HDGT.PPT/

First-Stage Nozzle Wear -

Preventive MaintenanceGas-Fired - Con t inuou s Duty - Base Load

Nozzle

Condition

New Nozzle Acceptance Standards

Repaired Nozzle

Min. Acceptance

Standard

1st

Repair2nd

Repair 3rd

Repair

Severe Deterioration

Repair Cost

Exceeds

Replacement

CostWithout

Repair

Operating Hours

10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000



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3HDGT.PPT/

Combustion Liners

Transition Pieces

Fuel Nozzles

Cross-Fire Tubes

1st Stage Nozzles

2nd Stage Nozzles

3rd Stage Nozzles1st Stage Buckets

2nd Stage Buckets

3rd Stage Buckets

1st Stage Shrouds

2nd/3rd Stage Shrouds

CI

CI

CI

CI

HGPI

HGPI

HGPI

HGPI*

HGPI

HGPI

HGPI

HGPI

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)

Repair

Interval

Replace

Interval

(Hours)

Replace

Interval

(Starts)

CI = Combustion Inspection Interval

HGPI = Hot Gas Path Inspection Interval

* When recoating, perform after one hours-based HGPI

** Two HGPI without recoat, Three HGPI with Recoat

Estimated Repair & Replacement



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3HDGT.PPT/

Maintenance Factors Summary

Maintenance Requirements are Based on an IndependentCount 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 SignificantlyIncrease Maintenance Factors and Reduce Component Life

Equations for Establishing Application Specific Hot GasPath Maintenance Intervals are Available



35/40

3HDGT.PPT/

Bucket Life Firing Temperature EffectMS6001B / MS7001EA / MS9001E

100

Life

Factor

1

10

0 50 100 150 200 250

0 25 50 75 100 125

Peak Rating

+100F (56C) T.

Life Factor -6

C

Change in

Firing

Temperature



36/40

3HDGT.PPT/

Operating Inspection Data ParametersSpeed

Load

Fired Starts

Fired Hours

Site Barometric Reading

TemperaturesInlet Ambient

Compressor Discharge

Turbine Exhaust

Turbine Wheelspace

Lube Oil Header

Lube Oil TankBearing 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



37/40

3HDGT.PPT/

Deterioration of Gas Turbine Performance

Due to Compressor Blade Fouling86

4

2

0-2

-4

-6

-8

-10

-12

-14

Heat Rate

Increase

%

Output

Decrease

%

-1 -2 -3 -4 -5 -6 -7 -8

5% Loss ofAirflow

Fouling

Fouling

Pressure Ratio Decrease - %



38/40

3HDGT.PPT/

Maintenance Inspections

Hot Gas Path Inspection - Key Elements

Foreign Objects Damage

Oxidation/Corrosion/Erosion

CrackingCooling Hole Plugging

Remaining Coating Life

Nozzle Deflection/Distortion

Abnormal Deflection/Distortion

Abnormal Wear

Missing HardwareClearance Limits

Potential Actions:Inspect for:Key Hardware

Nozzles (1,2,3)

Buckets (1,2,3)

Stator Shrouds

IGVs & Bushings

Compressor Blading

(Borescope)

Repair/Refurbishment

Nozzles

Weld Repair

RepositionRecoat

Buckets

Strip & Recoat

Weld Repair

Blend

Criteria: Op. & Instr. Manual TILs

Field Engineers

Inspection

Methods: Visual

LP

Boroscope

Combus t ion Insp ect ion Work Scope Plus :

Availability of On Site

Spares Is Key to

Minimizing Downtime



39/40

3HDGT.PPT/

Maintenance Inspections

Combustion Inspection - Key Elements

Foreign Objects

Abnormal Wear

Cracking

Liner Cooling Hole Plugging TBC Coating Condition


Hot Spots/Burning

Missing Hardware

Clearance Limits

Borescope Compressor andTurbine


Combustion Liners

Combustion Covers

Fuel Nozzles

Transition PiecesCross Fire Tubes

Flow Sleeves

Check Valves

Spark Plugs

Flame Detectors

Flex Hoses

Repair/Refurbishment

Liners

Cracking/Erosion/Wear

TBC Repair Transition Pieces

Wear

TBC Repair

Distortion

Fuel Nozzles

Plugging

Erosion/Wear Cross Fire Tubes

Wear/BurningCriteria: Op. & Instr. Manual

TILs

Field Engineers

Inspection

Methods: Visual

LP

Boroscope

Availability of On Site

Spares Is Key to

Minimizing Downtime



40/40

4HDGT.PPT/

Maintenance InspectionsGT Major Inspection - Key Elements

Foreign Objects Damage


Cracking

Leaks

Abnormal Wear

Missing Hardware

Clearance Limits


Compressor Blading

Turbine Wheels DovetailsJournal and Seal Surfaces

Bearing Seals

Inlet System

Exhaust System

Repair/Refurbishment Stator Shrouds

Oxidation/Corrosion/Erosion Buckets

Coating DeteriorationFOD/Rubs/CrackingTip Shroud DeflectionCreep Life Limit

Nozzles

Severe Deterioration IGV Bushings

Wear Bearings/Seals

Booring/Wear Compressor Blades

Corrosion/Erosion

Criteria: Op. & Instr. Manual TILs

Field Engineers

Inspection

Methods: Visual

LP

Borescope

Combust ion Inspect ion Work ScopeHotGas Path Insp ect ion Work Scope Plus

gt maintanance

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