performance analysis of industrial gas turbines for engine

Performance Analysis of Industrial Gas Turbines for Engine Condition

Monitoring

ByByK. Mathioudakis, A.

Stamatis, A. Tsalavoutas, N.

Aretakis

Lab. Of Thermal Lab. Of Thermal TurbomachinesTurbomachinesNational Technical University of AthensNational Technical University of Athens

u Introduction

u Condition Assessment Principles

u Direct Termodynamic Analysis

u Analysis Employng Adaptive

Modeling

u Implementation of Monitoring

Method

u Test Cases

u Conclusions

Assessing the Effects of Deposits on Assessing the Effects of Deposits on Turbine Turbine BladingBlading in A Twin Shaft in A Twin Shaft

Gas TurbineGas Turbine

Lab of Thermal TurbomachinesNational Technical University of Athens

Contaminantsdust,salt,ashesfuel additives

etc...

foulingerosioncorrosion etc...

increased surface roughnessloss of materialaerodynamic profile changereduction in blade throat area

reduced stall marginincreased temperaturesincreased fuel consumption inability to meet power

surge or rotating stallreduction in components lifeefficiency and performance

Deterioration causes & effectsDeterioration causes & effects

IntroductionIntroduction


What about maintenance?What about maintenance?

Early isolation of the root cause of problems allows the operators to

better plan the corrective maintenance actions and to avoid

harmful operating conditions.

For modern engines of modular

construction, need to detect faults to the

module level.



What about tools?What about tools?

These methods cannot in general quantify the condition of the engine

components and the contribution of each

module to performance shortfall.

Appropriate methods for fouling and/or performance deterioration detection have been proposed (for example Diakanchuk, 1991, Dundas

1992, 1993)



Maintenance decision levelsðA maintenance decision is usually taken in

two levels:ð (a) Fault Detection. must be judged whether

the machine is healthy or notð (b) Fault Identification: specifies fault

location, kind and severity.

ðEngine manufacturers normally provide users with performance specifications for a nominal engine.ðAs engines deteriorate or are subjected to

specific faults operator has no capability of identifying the cause of the problem

Condition Monitoring and Diagnostics : use measurements to infer the present and future status of the engine and its components in order to help maintenance decision making.

Condition Assessment PrinciplesCondition Assessment Principles


-6

0

6

(a)

-6

0

6

(b)

-6

0

6

( c)

-6

0

6

W P3 T3 Wf P41 T5 Ps

(d)

Wa p3 T3 Wf p41 T5 PS (a) Mistuned IGVs ↓ ↓ ~ ↓ ↓ ↑ ↓ (b) Compressor Fouling ↓ ↓ ↑ ↓ ↓ ↑ ↓ (c) Compressor-Turbine Fouling~ ↑ ↑ ↓ ↓ ↓ ↓ (d) Power Turbine Fouling ~ ↑ ↑ ↑ ↑ ↑ ↑

Adaptive Performance Model

XX f

ref

act=

Condition Assessment PrinciplesCondition Assessment Principles

Modification factor definition

Xref parameter value on the reference mapXact parameter value on the actual "on engine" map

Define full set of factors for all engine components

Calculate factors by solving an optimization problem

Target: measured quantities on the engine are identical to the corresponding calculated ones


A twin shaft gas turbine (ABB GT10)

The engine was installed and its first runs were performed on June 96. During efficiency testing, (November 96) an increased EGT was observed.

Analysis of the data was made at two levels :

Ø"common sense" thermodynamic analysisØadaptive performance modelling

The Case of a malfunctioning Industrial Gas TurbineThe Case of a malfunctioning Industrial Gas Turbine



Corrected EGT vs Corrected Load (Before and after intervention)

ISO AnalysisDiagnosing the problemDiagnosing the problem

The guidelines of ISO 2314 correction and calculation procedures were applied

80

85

90

95

100

105

50 70 90 110Reduced Load (%)

Red

uced

EG

T(%

)

Fouled

Initial

Recovered

ISO AnalysisDiagnosing the problemDiagnosing the problem


92

94

96

98

100

102

104

90 92 94 96 98 100 102 104 106 108

C omp ressor T urb ine Pressure R a tio (% )

q4 (%

)

Recovered

Fouled

Ini tia l A

B C

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

df1 df2 df3 df4 df5 df6

Perc

enta

ge D

evia

tions

Ps Wa P3 T3 Wf T5 P41

Deviations of measured quantities for 1% reduction of each individual modification

factor.

60

70

80

90

100

110

120

70 7 5 8 0 8 5 90 95 10 0 10 5 11 0

Reduced C om pre sso r Mass Flow (%)

Com

pres

sor

Pre

ssu

re R

atio

(%)

Resta ggered

Fouled

Ini tia l

Compressor Map Operating Points for different “health” conditions of the twin shaft

gas turbine.

-3.5 -3

-2.5 -2

-1.5 -1

-0.5 0

0.5 1

Initial Condition

Fouled Turbine

%

df1 df2

df3 df4

df5 df6

Health Indices Percentage deviation, for a gas turbine, which has suffered severe turbine fouling, caused by fuel

additives.

-5

-4

-3

-2

-1

0

1

2

0 10 20 30 40 50 60 70

Days

df5

(%)

Evolution of power turbine degradation over the initial period of engine operation

Compressor Efficiency vs. Time

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

0 10 20 30 40 50

Days

Perc

enta

ge D

evia

tion

(%)

Compressor Wash

Setup of the engine adaptive model

refP

P2

refC

C1

C

C

nn

=f qq =f

nn =f

qq =f

CT

CT

is ref

is

CT ref

CT43

nn =f

qq =f

PT

PT

is ref

is

PT ref

PT65

Compressor:

Core Turbine:

Power Turbine:

Diagnosing the problemDiagnosing the problem


Adaptive Modeling Results

-3.5-3

-2.5-2

-1.5

-1-0.5

0

0.51

06/1996 11/1996

%

df1 df2

df3 df4

df5 df6

Health Indices Percentage Deviation.


first period of operation :deviations of small magnitude, within the uncertainty limits

performance test : evidence of an increased responsibility of the hot section for the existing deterioration


Compressor Turbine 1st rotor blades.

Compressor Turbine 1st Stator vanes.Suction side view.



Inspection Results

Power Turbine 2nd Stator vanes detail.


Inspection Results

Power Turbine 2nd Stator vanes. Leading edge Suction side view.


ISO Analysis (Before and after intervention)

40 60 80 100 120Reduced Load (%)

70

80

90

100

110

Red

uced

TIT

(%)

03/1997

01/1197

11/1996

06/1996

40 60 80 100 120Reduced Load (%)

80

85

90

95

100

105

Red

uced

EGT

(%)

03/1997

01/1197

11/1996

06/1996

Turbine Inlet Temperature vs Corrected Load

Corrected EGT vs Corrected Load


Verification of Performance RecoveryVerification of Performance Recovery


98 100 102 104 106 108Compressor Turbine Pressure Ratio (%)

90

95

100

105

110

Red

uced

Com

pres

sor T

urbine

Flow F

unction

(%)

03/1997

01/1197

11/1996

06/1996

80 85 90 95 100 105Reduced Compressor Mass Flow (%)

70

80

90

100

110

Com

pres

sor P

ress

ure

Rat

io (%

)

03/1997

01/1197

11/1996

06/1996

Compressor Map Operating Points.

Compressor Turbine Operating Points.


ISO Analysis (Before and after intervention)

-3.5-3

-2.5-2

-1.5-1

-0.50

0.51

1.5

06/1996 11/1996 01/1997 03/1997

%

df1 df2

Compressor Health Indices Deviation.


-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

06/1996 11/1996 01/1997 03/1997

%

df3 df4

Compressor Turbine Health Indices Deviation.



-3.5

-2.5

-1.5

-0.5

0.5

1.5

2.5

3.5

06/1996 11/1996 01/1997 03/1997

%

df5 df6

Power Turbine Health Indices Deviation.



Flow capacity has clearly increased as a result of the re-staggering, while efficiency has been insignificantly influenced

In addition to the diagnostic ability,ability to verify the condition of the components after an intervention for modifications.


ConclusionsConclusions

Procedures for characterizing the condition of gas turbines have been presented.

An industrial gas turbine, which exhibited some problems in the hot section, was employed as a test vehicle.

Standard thermodynamic analysis can point out some aspects of malfunctionhoweveronly the application of a component level diagnostic technique can provide detailed insight about the condition of the engine components.

Using information available to the user, it is possible to predict the effects of geometry changes to its performance, with a good accuracy.


performance analysis of industrial gas turbines for engine

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