cc assessment -gross 07

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Mike Gross

Technical Leader CC

April 2007

Combined CycleAssessment

GEEnergy

2007 EuropeCombined Cycle

Performance Seminar



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GE Energy ± Proprietary TrainingInformation

Europe CC Performance Seminar ± April2007

HRSG Diagnostic

- Section Heat Transfer

- Steam Production

Condenser Diagnostic

- Cleanliness Factor

ST Diagnostic

- Section Efficiency

- Flow Capacity

- Valve DP¶s

HPLPIP

GT Diagnostic

- Airflow

- Compressor Efficiency

- Turbine Efficiency

- Firing Temp

Overall Plant Diagnostics

- Component Losses

- Cycle Isolation Losses

- BOP Losses

Combined Cycle Components

Each item shown is a potential contributor to performance

losses



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GE Energy ± Proprietary TrainingInformation

Europe CC Performance Seminar ± April2007

Combined Cycle Diagnostic Process

1) Define Test Setup

2) Test - Overall & Component

3) Validate Test Data

5) Establish Component Losses

6) Reconcile Results

7) Report Results

4) Determine Baseline



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GE Energy ± Proprietary TrainingInformationEurope CC Performance Seminar ± April

2007

Test Case

Plant Description: 107FA, 3-pressurereheat combined cycle plant, in operation

12 years. Capable of simple cycle

operation via operation of bypass

stack/damper.

Test Goal: Determine

repairs/modifications to make to steamcycle (steam turbine and HRSG) during

the next scheduled planned outage.



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2007

Step 1: Define Test Setup

1

289 24

29

36

25 3717

26

12 42 41

403227 10

4849

351318

0

333 4311

346 8

7

2 14

5

HRSG

2

6

3

97

5

4

50MW

HP 2

6

3

97

5

4

50MW

IP/LP

GEN

POWER OUT

Power OutputPower Factor

B Y P A S S

FlowTemperatureComposition Temperature

Pressure

TEST BOUNDARY

Develop a thermal model of plant based on design

or new & clean conditions.

Define test measurements/instrumentation



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Step 1) Define Test «continuedGT Measurements (for GT exhaust conditions)

Measurements

TI ET, PI ET, Humidity

GT Po er utput, P

uel DP, P, T,Constituents

GT Exhaust Temp

Design Info

Generator loss curves

GT ixed osses

Combustion efficiency



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Step 1) Test-Setup «continuedHRSG Measurements

(mass & energy balances, section performance) ater/Steam

± P and T In and ut of each economizer and superheater

section

± P, DP and T Across feed ater, spray flo sections.

± P, DP, T across P Steam flo section

± Drum, superheater outlet pressures

Exhaust Gas

± T Into HRSG (GT Exhaust Temperature) ± T ut of HRSG (Stack Temperature)

± GT easurements for Energy alance

Legend : Precision Measurement | Station Measurement



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Step 1) Test-Setup «continuedSteam Turbine Measurements

(mass & energy balances, section efficiencies)

T

T T

P P

P P

Cold

Reheat

Steam

HP

Admission

Steam

Stop/Control Valves

Main SteamHot Reheat

Steam

Intercept Valves

To Condenser

P

IP/LP

P

T

HP Bowl

Generator Output

Power Factor

P

IP Bowl



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Step 2) Test Conduct

Data Collection Period ± collect at least

t o test points of one hour duration.

Data sampling intervals - at least 30

readings per test point.

Cycle Isolation

Plant peration



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Step 2) Test Conduct«continuedCycle Isolation

HRSG / Steam Turbine Leaks

pen Cycle eaks ( ater or steam leaves the closed cycle and must be

replaced ith make-up ater)

Closed Cycle eaks ( ater or steam bypasses an important component

of the cycle, but does not leave the cycle)

Open Cyclelo do n excessive

oose pipe flangeseaking valve stems

eaking drains to dump

DA Vent open too much

eaking relief valves

Closed CycleDrain Valves to Condenser leak

Turbine ypass Valves leakDA Dump valve leaks

High evel Drains leak

Steam seal feed/dump valve leaks

Examples



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Step 2) Test Conduct«continuedCycle Isolation: Detection methods

Visual Inspection (drips, steam clouds)

Steam audibly leaking through valve.

Temperature measurement upstream/downstream of closed

valves.

Double valve isolation with tell-tale

Change in water Level (Manually close isolation valves for make-

up. Record condenser hotwell and drum levels during the test.

The drop in the levels can be used to calculate a volume change.

Divide the volume change by the amount of time the test took todetermine the rate of water loss). This method can be used to

measure total open-cycle leaks.

Close leaking valve and detect change in corrected kW (for big

leaks).



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Step 2) Test Conduct«continuedPlant Operational Checks

Plant operating as intended

Valve line up

Control (i.e. GT at base load, duct burners on or

off)

Plant has reached steady-state conditions

Data acquisition system functioning



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Step 3) Data ValidationData Validation Techniques

Comparison to expected readings

Comparison to redundant measurements

Mass balances

Energy balances

Physical principles



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Step 3) Data Validation

Comparison to expected

readings:

Pre-test expected

readings generated from

cycle thermal model, and

used for comparison with

test readings prior to test.

Helps detect gross errors

in test data.

xpected Steam Cycle Readings, 8 , 4.5 psia

Steam ur ine

xpected Readings Pressure emperature

ain Steam 13 8.7 72.3

ot e eat 310.1 1007.5

Cold e eat 33.4 334.5

P Steam 5 .0 472.4

HRS

LP Econ Inlet 5 . 4.5

LP Econ utlet 2 .0

LP Drum Pressure 5 .

LP Super eater utlet 472.4

IP Econ Inlet 417.2

IP Econ utlet 428.2

IP Drum Pressure 350.5

IP S utlet 5 4.1

S utlet 1008.0

P Econ Inlet 432.5

P Econ utlet 585.0

P Drum 1531.4

P S utlet 7 .8

Data Validation echniques



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Step 3) Data Validation«continued

Data Validation Techniques

Mass Balances:

Comparison of total condensate flow vs. sum of feedwater &

attemporation flows.

Measured Mass Balance DifferenceHP eed ater 375,924

IP eed ater 60,222

HP Spray 13,739

RH Spray 10,641

P Steam 25,613

Total Condensate 489,883 486,139 -0.76%

Re-verify measurement if

outside the uncertainty of the

measurement(s)



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Step 3) Data Validation«continuedData Validation Techniques

Energy

Balances:

Comparison

of energy

released byexhaust gas

to energy

gained by

steam/water

in HRSG.

Gas Side 1

Inputs

low¡

ressure Temperature h [Btu/lb] H [Btu/hr]

¢

£

SG Inlet Gas 3,1¤

1,8¥

9 11¥

2.26 282.¥

901,¥

27,658

GT E¦ § aust Gas Composition

Argon 0.0087

̈

2 0.732¥

©

2 0.1261

C©

2 0.0367

¢ 2© 0.0961

utputs

Stack Temperature 3,191,8¥

9 235.9 38.3 122,131,¥

91

Energy Lost rom Gas Side 779,296,166

Heat

tilization

actor (£

adiation,

isc Losses) 0.9950

%

lo

to HRSG Heat Xfer Sections (

ypass Leakage) 99.8%

Gas-Side Energy Release

,4

,

8

Steam/ ater SideInputs

low¡


Condensate In ( rom ass alance) ¥ 86,139 72.85 105.0 73.18 35,57¥ ,987

Cold Re§ eat Steam In 379,659 3¥ ¥ .5 692.1 1362.23 517,18¥ ,132

IP

eed

ater 60,222 37¥

.0 308.6 0.00 0

HP

eed

ater 375,92¥

1766.1 311.¥

0.00 0

HP

eed

ater Pump Energy 2,563,879

IP

eed

ater Pump Energy 865,365

Energy In 556,188,363

utputs

low¡


HP Steam 389,663 1333 996.25 1¥

93.1 581,793,889

RH Steam ¥ 50,521 31 ¥ .99 1003.8 1527.7 688,283,206

LP Steam 25,613 68.18¥

99.1 1281.9 32,83¥ ,922

HP

lo

do

n 0 1¥ ¥

6.1 60¥

.8 0

IP

lo

do

n 0 351.92¥

10.¥

0

Energy©

ut 1,302,912,016

Energy Gained

rom Steam Side Steam-Side Energy Gain

4

,

,

5

Gas to ater/Steam Imbalance - .5%ad data or real

problem?



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Step 3) Data Validation«continuedData Validation Techniques

Fluid dynamics:

Compare design K-factor to Test K factor for ST sections

HP Section Design Test Difference

HP Throttle lo 378,399 389,663

HP Throttle Pressure 1,354.0 1,308.6

HP Throttle Temperature 1001.1 995.4

HP Throttle Enthalpy 1495.3 1493.3

HP o l Pressure 1293.1 1297

HP o l Specific Volume 0.6312 0.627

K- actor 8360.1 8568.6 2.5%

Used to detect gross errors in test data.

Typical as built K-factor within % of original design.

If stage physical condition stays constant, K factor will

be constant over time.



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Heat Transfer

Sub-cool

Pinch

Heat Transfer Limitations:

As evaporator surface area p gpinch point approacheszero.

Pinch can not be negative.

Step 3) Data Validation«continued



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Step 4) Establish aseline Performance

Run design/new & clean thermal model at test

boundary conditions to establish expectedperformance at test conditions. UNITS TESTED EXPECTED

Boundary conditions

GT exhaust gas flo lb/hr 3,192,902 3,192,902

GT exhaust gas pressure psia 15.1 15.1

GT exhaust gas temperature 1,143.3 1,143.3

GT exhaust gas Carbon Dioxide mol frac 0.03640 0.03640GT exhaust gas H2 mol frac 0.09557 0.09557

GT exhaust gas itrogen mol frac 0.73263 0.73263

GT exhaust gas xygen mol frac 0.12668 0.12668

GT exhaust gas Argon mol frac 0.00872 0.00872

Steam turbine exhaust pressure 1.0083 1.0083

Cycle Measurements/Predictions

ST output k 77,238 84,147

Stack temperature 236.3 216.5

Predicted Design utput 84,147

easured ST utput 77,238

Steam Cycle Shortfall 6,909

Steam Cycle

Shortfall



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21 /GE Energy ± Proprietary Training

InformationEurope CC Performance Seminar ± April

2007

Step 4) Establish Component osses

Component

esi n t est

oundar Conditions

Fi pass

Damper

Desi n DP

R

ew

HP SH1

New

HP SH3

New HP

ap

New

HP con 1

ypass amper ESIG TEST TEST TEST TEST TEST TEST

HP RV DESIG DESIG TEST TEST TEST TEST TEST

HP SH1 DESIG DESIG DESIG TEST TEST TEST TEST

HP SH3 DESIG DESIG DESIG DESIG TEST TEST TEST

HP E ap DESIG DESIG DESIG DESIG DESIG TEST TEST

HP Econ DESIG DESIG DESIG DESIG DESIG DESIG TEST

Steam Cycle utput 84,147 81,090 81,181 81,211 81,219 81,281 80,952Component

Impact 0 -3,057 91 30 7 2 -329

Incr ementally change components in

design model and r er un model at testboundar y conditions

Performance Impact of

ComponentDesign

Prediction



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Step 5) Reconcile Results

Do component impacts add up to total plant shortfall?

Can be a sign of measurement errors.

Do component impacts make sense?

Is an individual component behaving much better

than design?

You may need to return to Step 3



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Step 6) Report Results



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Step 6) Report Results«Continued



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2007

Supplemental Diagnostic Techniques(non-thermodynamic)

HRSG surface temperatures ± used to detect

gas bypass.

Visual Inspection.

Thermal Image of HRSG Roof



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2007

Supplemental Diagnostic Techniques(non-thermodynamic)

HRSG skin temperatures

0

100

200

300

400

500

600

1 2 3 4 5 6 7 8 9 10

Strut

T e m p e r a t u r e [ F ]

HRSG 1A

HRSG 1!



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2007

Supplemental Diagnostic TechniquesHRSG visual inspection ± damaged & missing lower baffle



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2007

Bypass damper/ exhaust duct

1. Install a temporary cap on the bypass damper for the next performance test to

eliminate bypass leakage. Investigate replacing damper at an future outage.3. eld repair all visible cracks in the duct upstream and do nstream of the bypass

damper.

4. Inspect the exhaust expansion joints located at either side of the bypass damper

and repair or replace as necessary.

HRSG1.Replace HP attemporator control TC. It currently reads high, and caused a 97 k

loss at test conditions.

2. Install redesigned baffling (side, center-line, upper and lo er) throughout the HRSG

to direct the exhaust gas flo to the heat transfer surfaces. Perform full inspection of

the HRSG sections at the next outage.

3. Clean the P economizer section per the HRSG manufacturer¶s recommendations.

ST

1. ST Improvements/ odifications: Conducting a full steam path audit at next full

outage to determine specific component replacement plan. Component

repair/replacement recommendations shall be based on the steam path auditor¶s

recommendations.2. verhaul leaking IP bypass valve.

Recommendations



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2007

Combined Cycle Assessment

Use thermodynamic analysis to pinpoint areas of focusand provide basis for economic justification of

repairs/modifications.

By itself, thermodynamic assessment does not reveal a

root cause for performance shortfalls. Combine withexperience and visual hardware inspection to create an

actionable maintenance outage plan.

Validate results with a post modification test and

analysis.

Document your findings/results to build up internal

library of lessons learned.

cc assessment -gross 07

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