Site Performance Testing of CW251B10 Gas Turbines

THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS 89-GT-142345 E. 47 St., New York, N.Y.10017

E s The Society shall not be responsible for statements or opinions advanced in papers or in dis-cussion at meetings of the Society or of its Divisions or Sections, or printed in its publications.Discussion is printed only it the paper is published in an ASME Journal. Papers are availablefrom ASME for fifteen months after the meetingPrinted in USA.

Site Performance Testing of CW251 B10 Gas Turbines

IHOR S. DIAKUNCHAK and DAVID R. NEVIN

Gas and Steam Turbine EngineeringTurbine & Generator DivisionWestinghouse Canada Inc.Hamilton, Ontario, Canada

ABSTRACT

The site performance testing of CW251 B10 industrial gas turbineengines is described in this paper. A brief description is provided of thetest procedure, the special instrumentation used during the test, andthe derivation of the test tolerances. The test data analysis method andthe associated correction curves and tables are described in somedetail. Typical engine site performance test results are presented andcompared to the original predicted engine performance.

INTRODUCTIONThis paper describes briefly the procedure used and the results

obtained from the site performance tests carried out on three CW251 B10engines. The CW251 B10 engine (see Figure 1) is a 42.5 MW classindustrial gas turbine, designed for 50 and 60 Hz utility and industrialservice in simple cycle, combined cycle and cogeneration applications(Kuly, 1986). In order to verity the mechanical integrity and engineperformance of the latest model in the W251 engine series, fully loadedfactory tests were carried out on the first two CW251 B10 engines builtin Canada. The extensive instrumentation incorporated into the en-gines confirmed the achievement of the mechanical integrity andperformance objectives (O'Neill, 1986, Diakunchak and Nevin, 1986).

and the instruments are calibrated prior to the test. Following thecompletion of the performance test the special instrumentation isremoved and the engine is restored to its normal operating condition.The duration of the actual test is less than a day, but up to threeadditional days are required for preparations before the test and specialinstrument removal after the test.

The test results are either reduced and corrected to the guaran-tee conditions manually or with the aid of a Personal Computer. Thecorrected results are then compared to the guarantee values of outputpower and heat rate, with account taken of the appropriate measure-ment uncertainty. Evaluation of site performance test data on threeengines demonstrated that the guarantee output power was exceededby a substantial amount and the heat rate was approximately as perguarantee.

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The site performance test is carried out as soon as possible afterthe completion of engine commissioning and shakedown testing, inorder to ensure that the engine is in a clean condition and that the inlet ^ €filter and compressor are not fouled. The objectives of the site performance test are as follows: k .;:

1.To determine the output power and heat rate of the gas turbinegenerating plant for the purpose of demonstrating the compliancewith the contractually guaranteed performance.

2. To obtain a "bench mark" of the new and clean engine performance,environmental temperatures (e.g. disc cavity temperatures), inletflow, duct losses etc., for use in future engine health monitoring andtrouble shooting.

To obtain satisfactory accuracy in the test results both station in-strumentation and special high precision instrumentation are utilized

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FIGURE 1- CW251 B10 ENGINE

Presented at the Gas Turbine and Aeroengine Congress and Exposition—June 4-8, 1989—Toronto, Ontario, Canada

Copyright © 1989 by ASME

Downloaded From: https://proceedings.asmedigitalcollection.asme.org/ on 02/01/2018 Terms of Use: http://www.asme.org/about-asme/terms-of-use

ENGINE DESCRIPTIONThe longitudinal cross-section of the CW251 B1 0 engine is shown

in Figure 2. The engine cylinders are horizontally split to expedite fieldmaintenance without the necessity of rotor removal. The engine has abell mouth style inlet cylinder and is equipped with variable compres-sor inlet guide vanes. The compressor is a 19 stage design with modestaerodynamic loading, low Mach numbers, excellent efficiency andgood stability. The compressor discs are shrunk on to a hollow forgedshaft. The blades are machined from envelope forgings and the statorsare either cast in segments or fabricated into diaphragms from ma-chined airfoil segments. The combustion system consists of eight cansand is capable of operating on a wide range of gas turbine fuels. It hasprovision for dual fuel operation and for either steam or water injectionfor NO X suppression. The goose-neck style transition ducts direct thecombustor exit gases into the turbine and are designed to minimize thetemperature gradients and flow distortion at the turbine inlet.

The three stage turbine is a design based on the latest designtools, which result in high overall efficiency and long service life of theturbine airfoils. The three turbine discs are connected through CURVICclutches, which are made up of toothed connection arms that extendfrom adjacent discs and interlock when the discs are bolted together.All turbine stators and the first two stages of blades are cast. The thirdstage blade is forged. The turbine disc cooling air and the cooling air tothe first two stages of blades is bled from the compressor exit, cooledin a cooler and filtered. The blades are cooled with spanwise holes. Thefirst stage stator cooling scheme utilizes compressor delivery air andconsists of two full impingement inserts, three rows of surface ejectionholes, pin fins in the trailing edge region and trailing edge ejection holes.Air bled from the compressor thirteenth stage is used to cool the sec-ond stage stators, which also incorporate two full impingement insertsand trailing edge cooling air ejection.

The turbine exit flow is exhausted axially through an annular ex-haust diffuser incorporating six tangential struts supporting the hot endbearing housing. The two engine bearings are of the inherently stabletilting-pad type and the thrust bearing is the double-acting tilting shoetype. The gearbox and the generator are connected to the cold end ofthe engine, thus eliminating the need for a flexible coupling.

TEST PREPARATIONIt is required to complete the site performance acceptance test as

soon after initial synchronization as possible, in order to minimize therisk of testing a dirty engine. Normally the test should be conductedwithin 30 days of synchronization.

Prior to performing the test, the compressor intake, includingfilters, bell mouth and inlet guide vanes, are inspected for the presenceof dirt and debris. When necessary, a soak wash and/or a dry mediaabrasive cleaning are performed. Soon after initial startup, a calibrationcurve of intake pressure depression versus referred engine speed isgenerated for determining any compressor fouling occurring in thefuture.

In order to conduct the performance test it is necessary to installsome special precision instrumentation used to measure key parame-ters. These principal parameters include:

Barometric pressureCompressor inlet temperatureTurbine exhaust temperatureOutput powerFuel consumption

At least one day, prior to the test, is required to install the specialinstrumentation and another day is required to remove the equipment.Additional checks required prior to the commencement of the test are:inspection of fuel nozzles, inspection of the exhaust system, and testingof the control system to ensure that the engine operates as planned ina stable fashion. Finally, it is important to have a fuel analysis perform-ed before the test, in order to provide a check on the engine heat rateduring testing and facilitate the detection of any possible engine orinstrumentation problems.

INSTRUMENTATIONA combination of station and special instrumentation is used in

the test. All instrumentation is calibrated before the test. All readoutdevices are located in a centralized, climate controlled environment,such as the control cubicle. A summary of the instrumentation and theparameters measured is as follows:

1. Power is measured by a polyphase wattmeter. The station powerconsumption is measured and accounted for.

2. The compressor inlet temperature (interpreted as the ambient tem-perature) is measured with eight additional thermocouples locatedin the compressor inlet manifold.

3. Barometric pressure is generally measured by a Fortin type Mer-cury barometer located outdoors near the unit.

4. Combustor shell pressure (compressor delivery pressure) is meas-ured by a transducer supplied with the control system and is com-pared against a special, high precision Bourdon test gauge.

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5.Turbine exhaust temperature is measured using eight additionalthermocouples installed in the exhaust system. The locations of thethermocouples have been selected on the basis of factory tests soas to provide the best measurement of the average temperature ofthe gases leaving the turbine.

6.Gaseous fuel flow rate is measured by an orifice meter installed inaccordance with American Gas Association Report NO. 3, "OrificeMetering of Natural Gas".

7.Turbine speed is measured using a speed pickup installed with thegas turbine.

8. Inlet and exhaust pressure drops are determined using water ma-nometers. Velocity head corrections are applied.

9. Environmental relative humidity is measured using a sling psy-chrometer.

10.Instrument air extraction and steam/water injection rates are meas-ured using appropriate flow measuring devices.

In items 2 and 5 above, total temperature recovery thermo-couples are not used, since the difference between the true total tem-perature and the measured temperature is usually small. Type "K"thermocouples immersed in a standard well are used.

TEST PROCEDUREWhenever possible, attempts should be made to operate the

engine at the site guarantee ambient conditions in order to minimize ad-justments to the raw data when referring power and heat rate to theguarantee conditions.

A thorough check is carried out by the director of the test to de-termine that conditions are suitable for the commencement of the testwith respect to the condition of the unit, installation of instrumentationand ambient conditions. Once acceptability has been established, theunit is started and brought directly to base load. After the turbine hasreached base load or design firing temperature as defined by the unitcontrol settings, it is allowed to stabilize for at least thirty minutes or untiloperating temperatures have achieved steady state. At the test engi-neer's signal, complete sets of data are taken at 5 to 10 minute intervals,until six sets of data are obtained. Upon the completion of base loaddata collection, the procedure is repeated for 75% and 50% load.

Several fuel samples are taken during the test for determinationof gas composition. These samples are analyzed at a vendor selectedlaboratory and at a laboratory selected by the purchaser. Any discrep-ancies in the compositions as determined by these labs can be resolvedby analyzing additional samples taken during the test.

Generally, the test procedure outlined above does not differ sig-nificantly from that outlined in ASME PTC22 and ISO 2314 test codes.

Method for Correcting Data to Reference ConditionsFinal test results referred to guarantee conditions are computed

using the raw values, as reported on the data sheets, and a series ofpower and heat rate correction factors to account for compressor inlettemperature, turbine speed, barometric pressure, exhaust tempera-ture, exhaust losses, etc.

The procedure for calculating the test results involves computingthe power and heat rate corrected to the site guarantee conditions foreach of the six base load data points. The corrected power and heat rateare then compared to the guaranteed values.

A description of the correction factors used in the calculations isas listed below:

1. Power Correction Factor for Barometric Pressure (P EAR ) — Thefactor to correct the power to the site guarantee pressure is calcu-lated from the equation:

PBAR = Site Guarantee Ambient PressureMeasured Ambient Pressure

To Correct for Compressor Inlet Temperature (PTIN , HRTIN) — Toobtain the correction factor for the power/heat rate at the inlettemperature measured during the test to the power/heat rate at thesite guarantee inlet temperature, a "Percent Power/Heat Rateversus Compressor Inlet Temperature Curve" is used. Example ofsuch a curve is shown in Figure 3. Relative humidity corrections arealso applied (P RH , HR RH).

FIGURE 3 - FACTORS TO CORRECT POWERAND HEAT RATETO REFERENCE CONDITIONS

3.To Correct for Non-Base Load Firing (PTExH , HRTEXH) — Since it ispossible that the engine may not initially be controlled at the desiredtemperature level as defined by the exhaust temperature versuscombustion shell pressure control settings, adjustments must bemade to account for the discrepancy. A set of correction factorsmust be applied to the Power and Heat Rate. These correctionfactors exist as curves and are typically as shown in Figure 4.

4.To Correct for Off-Design Running Speed (P N , HRN ) — Since gasturbine performance is generally quoted at a specific speed, anyvariations in such running speed must be accounted for. Figures 5and 6 present examples of speed corrections. These correctionsare not necessary when the engine feeds power into the grid.

5. To Correct for Inlet and Exhaust Loss (for non-standard duct con-figurations supplied by purchaser and for waste heat applications)( PLOSSIN' PLOSSEXH' HRLOSSIN , HRLOSSEXH) — Since performance isgenerally guaranteed at a specified level of inlet and exhaust loss,the measured values are to be corrected in the event that losses do


not meet the quoted levels. The correction factors are determinedusing curves of "Percent Change in Power and Heat Rate versusInlet and Exhaust Loss".

6. To Correct for Off-Design Power Factor (P PF) — In order to accountfor varying generator losses due to changing power factor, a curveof "Loss versus Power Factor" must be used.

7.To Correct for Varying Steam/Water Injection Rates (P INJ , HR^ NJ ) —In order to account for varying steam/water rates at differingambients, curves of "Power and Heat Rate versus Injection Rate"are used.

Any discrepancies between actual fuel composition and the onespecified for the performance guarantee are accounted for.

Using the above correction factors the corrected power and heatrate are determined as follows:

CORRECTED POWER = MEASURED POWER x

(BAR x PTIN x PRH x PTEXR x P N X PLOSSIN X PLOSSEXH X PPF X PINJ)

CORRECTED HEAT RATE = MEASURED HEAT INPUT x(HRTIN x HR RH x HRTEXH x HR N x HRLOSSIN x HR INJ )

(MEASURED POWER x P pF )

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VARIATION FROM DESIGN SPEED

FIGURE 5 - FACTOR TO CORRECT POWERFOR OFF - DESIGN ENGINE SPEED

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26.7 (80)

37.8 (100)

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FIGURE 6 - FACTOR TO CORRECT HEAT RATEFOR OFF - DESIGN ENGINE SPEED

1.02

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37.8 (100)

26.7 (80)15 (59)

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DEVIATION FROM CONTROL EXHAUST

TEMP, °C (°F)

FIGURE 4 - FACTORS ON POWER AND HEAT RATETO ACCOUNT FORNON BASE LOAD RUNNING

Uncertainty Associated withCorrected Power and Heat Rate

In order to assess the validity and confidence level to be assignedto the results of a performance test, it is necessary to do an uncertaintyanalysis on all parameters used in the final performance calculations.If at any moment in time one desires to know the power being produced

and the corresponding heat rate, the uncertainty involved in determin-ing these parameters is simply that of the power measurement (KW)and a combination of the power and fuel consumption in KJ/SEC (BTU/SEC). This assumes that one does not wish to refer these performanceparameters to a reference condition for comparison purposes.Undersuch conditions, it is possible to assign a reasonably narrow uncertaintyband around the results.

The confidence level associated with any uncertainty band is avery important consideration and directly reflects the credibility of anyresults obtained from a field test or any other test. Since a great deal ofimportance is placed on the result of a performance acceptance test,a 2cr (2 standard deviations) tolerance band is placed on the results.This represents a confidence level of 95%, and means that 19 times outof 20 the measured or calculated result will fall within the uncertainty

4


band specified. In the case of a test where one is interested only in theinstantaneous power level, such a value can be determined at a 95%confidence level with an uncertainty band of much less than ±1 %. If forthe same test one wishes to refer the measured power to anothercondition, one must include the uncertainties of the other measuredparameters, such as: ambient temperature, ambient pressure, exhausttemperature, compressor discharge pressure, engine exhaust backpressure (if waste heat boiler is installed), relative humidity, generatorpower factor and engine speed. In order to refer the measured heatrate, in addition to the preceeding parameters, the uncertainties in thefollowing parameters must be included: fuel flow, fuel temperature (ifrefinery gas or other heated process gas is utilized) and fuel composi-tion (required for the determination of fuel lower heating value).

The effect that each of the above mentioned variables has on thedesired referred performance values is determined. Since each pa-rameter is independent of the others, the net effect of all parameters isdetermined through the Root-Sum-Square of all variables (Abernethyet al., 1973).

Power UncertaintyWhen determining the uncertainty in the power calculation, it is

quickly realized that the measurement of power itself represents a verysmall uncertainty in the overall calculation. The most significant con-tributors to the corrected power tolerance, and their effect on thecorrected power, include:

Compressor Inlet Temperature = ±.54%Exhaust Temperature = ±2.06%Power Measurement = ±.5%

It has been determined that the Root-Sum-Square uncertainty onthe corrected output power measurement for the CW251 B1 0 engine is±2.2%.

Heat Rate UncertaintyThe primary contributors to the uncertainty level in the determi-

nation of heat rate, and their effect on the corrected heat rate, include:Fuel Flow = ±2%Fuel Composition = ±.8%Compessor Inlet Temperature = ±.3%Exhaust Temperature = ±1.1Power Measurement = ±.5%

The net combined uncertainty on heat rate is ±2.4% when testedon natural gas fuel. Details of the determination of the test measure-ment uncertainties on the corrected power and heat rate are given in theAppendix.

In waste heat energy applications, for which the exhaust energymust be determined, indirect calculation methods are normally re-quired and hence a greater degree of uncertainty is assigned.

SITE PERFORMANCE TEST RESULTSThe first Canadian-built CW251 B1 0 engine was installed at site,

commissioned and performance tested within two and a half months ofits arrival at the site. The engine application was in the cogenerationmode (see Figure 7). The site performance verification test was carriedout according to the test procedure described previously. Visualinspection of the engine inlet scroll and subsequent light manualcleaning of the inlet guide vanes and the first stage compressor bladesestablished that the compressor was clean. The fuel used during thetest was natural gas. During the test the inlet temperature was 24.4°C(76°F) and the ambient pressure was 99.29 KPa (14.40 PSIA). The inletand exhaust losses were 102 MM (4 IN) of water and 216 MM (8.5 IN)of water respectively. Prior to the performance test the engine wasrunning at low load for several hours. The engine was then loaded upto the desired output power level. It was maintained at this power levelfor approximately one hour to allow conditions to stabilize prior to therecording of test data. Some load fluctuations were experienced at thebeginning of the test. Six sets of the pertinent test data were recordedover a 30 minute period. This procedure was repeated for 75% and then50% load.

The test measurements were averaged as required, reduced andthe appropriate calibration corrections applied. The engine site outputpower, fuel flow and heat rate were determined for each test point. Thecorrection factors to be applied to the output power and heat rate toaccount for test conditions deviating from the guarantee point condi-tions were estimated. These corrections were then applied to the outputpower and heat rate and the corrected values were compared to the siteguarantee point numbers to obtain the margins on output power andheat rate. Table 1 shows the results of the estimation. The first two testpoints were omitted from the calculation because of load fluctuation.The average margins on the four base load test points were 3.26%surplus on output power and .6% excess on heat rate. These values do

FIGURE 7 - W251 B10 IN COGENERATION APPLICATION


not take into account the measurement uncertainty. Based on theresults of the performance test it was concluded that the engineachieved, and in the case of output power exceeded, its site guaranteepoint performance. In addition to the basic engine performance the testprovided valuable "bench mark" data on compressor inlet flow, ductlosses, engine temperatures and pressures, which could be used infuture engine health monitoring or performance trending. The cor-rected site output power and heat rate were compared to the expectedvalues based on the factory test results. The two sets of valuescompared to within one percent, thus giving added confidence to thevalidity of the site performance test results.

TABLE 1

GAS TURBINE PERFORMANCETEST CALCULATION SHEET

Load Level: Base loadSite Rated Guarantees: Power=40560 KW Heat Rate =11020 BTU/KW-HR

= 11626 KJ/KW-HRSite Rated Conditions: To =50° F Po = 29.23"Hg10°C 98.95 kPa

Run 1 2 3 4

Comb Shell Press 183 183 184 184Measured Exh Temp 946.4 940.7 943.7 943.0Control Exh Temp 966.2 966.2 965 965T2 Power Corr Factor 1.0371 1.0478 1.0410 1.0423T2 HR Corr Factor .9908 .989 .9898 .9895Turbine Speed 5424 5424 5423 5423N Pwr Corr Factor 1.0 1.0 1.0 1.0N HR Corr Factor 1.0 1.0 1.0 1.0Corr Barometer 29.318 29.318 29.318 29.318Po Pwr Corr Factor .9970 .9970 .9970 .9970Como Inlet Temp 77.06 76.94 76.0 75.31Ti Pwr Corr Factor 1.132 1.132 1.126 1.123Ti HR Corr Factor .9615 .9615 .963 .964Measured Net Power (KW) 36555 35838 36698 36698Corrected Power (KW1 41955 41546 42046 41986Gas Static Press 306.39 305.40 304.39 304.39Flowing Gas Temp 521.8 522.1 522.4 523.0Orifice Press Drop 6.250 6.141 6.069 6.286Thermal Exp Factor 1.000033 1.000039 1.000044 1.000056Com r - Flow Cond .968 .968 .969 .969Exp Factor 1.0029 1.0028 1.0028 1.0029Density - Flow Cond .9619 .9579 .9534 .9523Gas Flow - Flow Cond 21144 21000 20926 21311Relative Humidity 63 64 64 64RH Pwr Corr Factor .9996 .9994 .9994 .9994RH HR Corr Factor 1.0 1.0 1.0 1.0Exhaust Loss 5.5 5.5 5.5 5.5Corr Exh Loss 9.1 9.1 9.1 9.1PEX Pwr Corr Factor .9847 .9847 .9847 9847PEX HR Corr Factor 1.0155 1.0155 1.0155 1.0155

Corr Gas Flow 451886 447085 443336 450968Corr Heat Rate (BTU/KW-HR) 11138 11222 10891 11087Power Mar in KW 1395 986 1486 1426% Pwr Margin +3.44 +2.43 +3.67 +3.52HR Margin (BTU KW-HR 118 202 -128 67% HR Margin 1.07 1.83 -1.17 .61

Averages:Power = 41883 KW Margin = 1323 KW % Margin = +3.26%Heat Rate = 11085 BTU/KW-HR Margin = 65 BTU/KW-HR % Margin = +.59%

11695 KJ/KW-HR

The site performance test carried out on the next CW251 B10engine was as per the previously described test procedure with minormodifications. In this installation steam injection into the combustorbasket was employed for NO suppression. The test was carried out onnatural gas, at 4.4°C (40°F) inlet temperature, 100.91 KPa (14.636PSIA) ambient pressure, 86 MM (3.4 IN) of water inlet loss, and 366 MM(14.4 IN) exhaust loss. The corrected test results showed that theoutput power was 4.5% higher than expected and the heat rate wasthree percent better than expected. Since this engine incorporatedimprovements compared to the first one, its margin on power washigher. The site test output power was in excellent agreement with thefactory test result. The heat rate, although better than expected, waswithin the expected measurement uncertainty.

The site performance test on the third CW251 B10 engine, whichincorporated water injection for NO suppression, was carried out onnatural gas. The site test conditions were: 23.9°C (75°F) inlet tempera-ture, 101.06 KPa (14.657 PSIA)inlet pressure, 88 MM (3.5 IN) of waterinlet loss, and 229 MM (9 IN) of water exhaust loss. Corrected testresults showed that the output power was 5.9% better and the heat rate.3% worse than the guarantee values. This engine was not factorytested and hence comparison with the above results cannot be made.Although the output power margin appears higher than expected, it caneasily be explained by further improvements incorporated into thisengine and perhaps by the conservatism used in the estimation ofpower augmentation due to water injection.

Table 2 summarises the site performance test results and com-pares the performance of the three site tested CW251 B1 0 engines withthe original published performance. The site test results were correctedto the performance standard of the packaged CW251 B10 enginerunning on natural gas fuel, without injection, at ISO conditions.

TABLE 2

COMPARISON OF CW251 B10 ENGINE SITE TESTRESULTS WITH GUARANTEE PERFORMANCE

NOTE: The site test results are corrected to ISO conditions, with noinjection, and standard plant losses. The fuel is StandardNatural Gas.

OutputPower

KW

MarginOn Power

%

HeatRate

KJ/KW-HR

MarginOn HeatRate

%

Guarantee 41,200 - 11,442 -

Engine No. 1 42,540 3.26 11,510 -.6

Engine No. 2 43,050 4.5 11,099 3

Engine No. 3 43,630 5.9 11,476 -•3

During the performance tests part load performance test datawas obtained. Figure 8 compares the site relative heat rate variationversus percent of base load output power with the predicted variation.The agreement between predicted and actual results is excellent.

The exhaust flow and exhaust temperature were not guaranteedperformance parameters, but they were either estimated from the testdata or were measured during the course of the site performance tests.The compressor inlet flow, and hence the engine exhaust flow, were

0


estimated from the measured test data with the aid of the inlet scrollcalibration curve obtained from the factory tests on two of the threeengines. In both cases the flow was about 2% higher than predicted andconsistent with the factory measurements. Since the CW251 B10engines are controlled to a specified exhaust temperature, the sitemeasured exhaust temperatures on all three engines would be asexpected with the engines operating at base load.

Gas turbine engine exhaust emissions are of significant environ-mental concern in most new installations. However, as a result of theplant commissioning schedule considerations, in none of the three siteperformance tests described in this report were the official emissionscompliance tests carried out at the same time as the performance tests.The official emissions tests were carried out many months after theperformance tests on all three engines. In one case, preliminaryemissions testing was done in conjunction with the performance test.The results of this test showed that NO x and CO emissions wereconsiderably lower than originally predicted for the CW251 B10 engine.

._\ 26.7°C (80°F)

-15°C (59°F) PREDICTED4.4°C (40°F)

Qr SITE AMB.

- SYMBOL ENGINE TEMP °C ('F)WI 0 No. 1 24.4 (76)W C1 No. 2 4.4 (40)

JWI

110.

. _. ,,. 4". 50. 60. .,. 0.

PERCENT BASE LOAD POWER

FIGURE 8 - RELATIVE HEAT RATE VERSUSPERCENT BASE LOAD POWER

CONCLUSIONS1.The site performance test method and test data analysis procedure

described in this paper ensure that the site performance of anindustrial gas turbine is accurately assessed and the compliancewith guarantee values demonstrated.

2.The site performance test provides valuable information for futureengine health monitoring and trending of important engine parame-ters.

3.The site performance tests carried out on three new CW251 B10engines demonstrated that they achieved the guarantee perform-ance.

4.The margin on power varied from about 3% to about 6%.5.The heat rate was as per guarantee.6.The site performance test results were in good agreement with the

performance information obtained previously on the same enginesfrom the factory tests.

REFERENCESKuly, P., 1986, "The CW251B10 Gas Turbine Engine," ASME

Paper No. 86-GT-82.O'Neill, S.T., 1986, "Full Load Development Testing of a 41 MW

Single Shaft Generator Drive Gas Turbine," ASME PaperNo. 86-GT-69.

Diakunchak, I.S. and Nevin, D.R., 1986, "Fully Loaded FactoryPerformance Test of the CW251B10 Gas Turbine Engine," ASMEPaper No. 86-GT-71.

ANSI/ASME PTC 22-85, Performance Test Codes, "Gas Tur-bines Acceptance Test."

International Standard, ISO 2314, "Gas Turbines - AcceptanceTest," First Edition, 1973-03-01.

Abernethy, et al., 1973, "Handbook Uncertainty in Gas TurbineMeasurements," Arnold Engineering Development Center, PublicationNo. AD-755-356.

L

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APPENDIX

CW251B10 ENGINE POWER AND HEAT RATEMEASUREMENT UNCERTAINTY

Using Instrumentation as per CW251 B1 0 Test Specification

1. POWER

1.1 Power MeasurementWattmeter Error = ±.33%Calibrated Potential Transformers = + .3%Calibrated Current Transformers = ± .1%

Total Uncertainty = ± f332 + .3 2 + .1 2 = + .5%

1.2 Inlet Temperature MeasurementInlet Temperature Thermocouple Uncertainty = + 2°F(1°F error =-.35% on power; 8 thermocouples used)Error = (2/I)x.35 = ±.25%Digital Readout ±.5°F; Error = ±.18%Uncertainty due to Sampling = (3.55/N)x.35 = ±.44%

Total Uncertainty = ± L252 + .18 2 + 442 = ±.54%

1.3 Exhaust Temperature MeasurementExhaust Temperature Thermocouple Uncertainty = ±7°F(1°F error =-.19% on power; 8 thermocouples used)Error = (7//)x.19 = ±.47%Computer Error (1°F) = ±.19%Uncertainty due to Sampling = (9.7/)x.19 = ±.65%Combustor Shell Pressure (CDP) Uncertainty = ±.75psi 10°FError due to CDP = ±1.9%

Total Uncertainty = ± .47 2 + .19 2 + .65 2 + 1.9 2 = ±2.06%

1.4 SpeedFrequency Meter Uncertainty = ±.1% on SpeedError on Power = ±.3%

1.5 Barometric PressureBarometric Pressure Uncertainty = ±.02 "HgError on Power = ±.07%

1.6 Total Output Power Measurement Tolerance

Power Measurement Tolerance = + .5z + .54 2 + 2.062 + 32 + .07 2

= ±2.2%

2. HEAT RATE

2.1 Gas Fuel Flow MeasurementFuel Flow Uncertainty = ±2%

2.2 Fuel Heating ValueUncertainty due to Fuel LHV = ±.8%

2.3 Inlet Temperature MeasurementInlet Temperature Thermocouple Uncertainty = ±2°F(1°F error =-.2%/°F on heat rate)Error = ±(2/°)x.2 = ±.14%Digital Readout = ±.5°FError on Heat Rate = ±.1%Sampling Error = ±(3.55/f)x.2 =Total Uncertainty =±.142 + .1 2 + .25 2 = ±.3%

2.4 Exhaust Temperature MeasurementExhaust Temperature Thermocouple Uncertainty = ±7°FEffect on Heat Rate =Error = ±(7/f)x.1 = ±.25%Computer Error (1°F) = ±.1%Sampling Error = ±(9.7/°)x.1 =±.34%Combustor Shell Pressure Uncertainty =

±.75 psi ±10°F= Error = ±1

Total Uncertainty = ±.252 + .1 2 + .34 2 + 1 2 = ±1.1%

2.5 SpeedError on Heat Rate = ±.02%

2.6 Power MeasurementError in Wattmeter and Accessories = ±.5%

2.7 Total Heat Rate Measurement ToleranceHeat Rate Measurement Tolerance

=± 22 + .8 2 +.32 +1.1 2 +.02 2 +.52=±2.4%


Documents

Site Performance Testing of CW251B10 Gas Turbines