Shop Test of the 501F A 150 MW Combustion Turbine

Transcription

1 THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS 345 E. 47 St., New York, N.Y GT-362 The Society shall not be responsible for statements or opinions advanced in papers or In discussion at meetings of the Society or of its Divisions or Sections, or printed in its publications. MDiscussion is printed only if the paper is published in an ASME ournal. Papers are available ]^L from ASME for fifteen months after the meeting. Printed in USA. Copyright 1990 by ASME Shop Test of the 501F A 150 MW Combustion Turbine D. T. ENTENMANN Manager, Stress and Dynamics W. E. NORTH Fellow Engineer Westinghouse Electric Corporation Technology & Strategic Operations Div Orlando, Florida I. FUKUE Manager, Gas Turbine Design Section A. MUYAMA Design Engineer Mitsubishi Heavy Industries, Ltd. Takasago Machinery Works Takasago, apan ABSTRACT The 501F is a 150 MW-class 60 Hz engine jointly developed by Westinghouse Electric Corporation and Mitsubishi Heavy Industries, Ltd. This paper describes the full load shop test program for the prototype engine, as carried out in Takasago, apan. The shop test included a full range of operating conditions, from startup through full load at the 1260 C (2300 F) design turbine inlet temperature. The engine was prepared with more than 1500 instrumentation points to monitor flow path characteristics, metal temperatures, displacements, pressures, cooling circuit characteristics, strains, sound pressure levels, and exhaust emissions. The results of this shop test indicate the new 501F engine design and development effort to be highly successful. The engine exceeds power and overall efficiency expectations, thus verifying the new concepts and design improvements. INTRODUCTION The 501F engine, jointly developed by Westinghouse Electric Corporation and Mitsubishi Heavy Industries, Ltd (MHI) is the latest, largest, and most advanced in a long line of single shaft heavy duty industrial combustion turbines. This engine combines the proven design features of the W501D5 [1] with advanced cooling schemes, including technology used in the MF111 [21, as well as the low NOx combustion technology of the MW701D [3]. This results in a highly efficient and powerful combustion turbine that will be available for 1990 operation and can satisfy the needs for both simple and combined cycle application in the foreseeable future. It will operate on all conventional combustion turbine fuels, incorporating dual fuel nozzles and technology when requested, and also with coal derived low BTU gas produced in an integrated gasification combined cycle power plant (IGCC) [4]. The engine incorporates a highly efficient 16 stage axial compressor, low NOx combustion system, and a four stage turbine with a flow path designed utilizing fully three dimensional analysis techniques. The plant performance characteristics preiented in Table I are for a turbine inlet temperature of 1260 C (2300 F) for the mature rating and 1210 C (2210 F) for the initial rating. A general description of the engine is presented in References [51 and [6]. As an integral part of any engine development program, testing includes advanced technology component verification testing, full load shop testing, and prototype field testing. This paper describes the component and shop test programs. The shop test results are presented here with respect to the overall design considerations. Detailed shop test data evaluation is continuing and will serve as the basis for further design improvements, some of which are noted herein. The results of these studies will be the subjects of further publications. ENGINE DESIGN FEATURES A longitudinal section of the 501F engine is shown in Figure 1. A summary of the basic design features is presented below, with those features unique to the 501F listed separately. The pre-501f list is a modification of that presented in Reference [71. Pre-501F Features - Cold end generator drive to eliminate the need for a flexible coupling. - Horizontally split casings to facilitate field maintenance with the rotor in place. - Two bearing rotor with the compressor and turbine portions joined by a center coupling. - Variable inlet guide vane (IGV) to provide exhaust temperature control for heat recovery applications and to improve starting characteristics. - Compressor diaphragms and dove-tail rooted blades removable with the rotor in place. 1 Hereinafter referred to as TIT or RIT (Rotor inlet temperature). Presented at the Gas Turbine and Aeroengine Congress and Exposition une 11-14, 1990 Brussels, Belgium This paper has been accepted for publication in the Transactions of the ASME Discussion of it will be accepted at ASME Headquarters until September 30, 1990

2 Figure F Longitudinal Section. - Three (3) axisymmetric compressor bleeds for turbine cooling with two (2) used to avoid surge during starting. - Combustors and transitions removable without lifting cylinder covers. - Turbine rotor with bolted, CURVIC 2 coupled discs. - Fir-tree rooted turbine blades removable onsite with rotor in place. - Multiple turbine blade ring concept to provide field service of stators with the rotor in place. - Cooled stage 1 and 2 vane segments and cooled stage 1 and 2 blades. - Stage 1 vanes removable without lifting cylinder cover. - Tangential exhaust casing struts to maintain rotor alignment. 501F Additional Features - Compressor blade locking feature that is visibly inspectable. - Blade rings in compressor section to optimize cylinder to rotor alignment. - Advanced hybrid combustor system, or pre-mixed system, incorporating low - NOx features. - Combustor transition cooling scheme which takes benefits of asymmetric external cooling characteristics of combustor shell flow. - Bolted compressor rotor design which eliminates a main coupling joint, as found on the W501D5 design, to increase rotor dynamic stability margin as well as facilitate fabrication and maintenance of the rotor. - Cooled stage 3 vane segment and turbine blade to improve reliability stage newly designed, highly efficient axial flow compressor incorporating larger diameter rear stages to help balance spindle thrust and two exit guide vanes, instead of one, to straighten the flow leaving the compressor. - Turbine flow path design utilizing fully three dimensional flow analysis. 2 Trademark of Gleason Works - ournal bearings consist of two-element tilting pad bearings for load carrying and an upper half fixed bearing to eliminate top pad fluttering concerns and related local babbitt spragging. - Leading edge groove (LEG) direct lubricated thrust bearing to reduce the required oil flow and its mechanical loss. - Integral "Z" tip shrouds in third and fourth stage rotors to minimize the potential for flow induced non-synchronous vibration. - Use of segmented isolation rings in the turbine vane segment support scheme to minimize blade ring distortion. - State-of-the-art turbine blade and vane segment cooling schemes to increase reliability and overall engine efficiency. COMPONENT VERIFICATION TEST PROGRAM Prior to the engine shop test, critical components which are unique to the 501F engine were tested to assure performance and reliability, using special test rigs and facilities. The tests included: A. Rotating Blade Vibration Test B. Turbine Aerodynamic Test C. Combustion Test 0. Turbine Cooled Parts Heat Transfer Tests Rotating Blade Vibration Test Natural frequency and vibratory stresses of compressor and turbine blades for selected stages were. checked during a high speed rotor balancing test to assure that those blades were well tuned. During the test, the actual fully bladed rotor was driven by an electric motor up to 110% of rated speed in a vacuum room. The frequencies and amplitudes of compressor blade vibration for the 1st, 2nd, 4th and 7th stages were measured using a non-contact optical fiber monitoring system. This system showed the movement of each individual blade tip by monitoring the position of each blade tip from several different locations circumferentially and analyzing this information through a synchronizing process. The schematic of this measuring system is shown in Figure 2. In the turbine, strain gauges were applied directly to the blades of each stage and the measured strain signals

3 were transmitted to a data acquisition system through the telemetry system as shown in Figure 3. After analyzing all measured data, it was confirmed that no further tuning was necessary for the blades. 5 H r 6H t^ n \ r^...^ 7 H 4W ^t? '. c '. f l l - 501F turbine airfoils were designed utilizing fully three dimensional analysis techniques. From the above tests, however, the effects of the three dimensional design on performance could not be estimated. Therefore, model turbine tests using scaled row 4 vanes and blades were conducted. The test rigs are shown in Figure 4. The test results displayed in Figure 5 show that the stage efficiency goal was met. The data confirmed that the original design objectives were satisfied. OPTICAL FIBER CABLE #1 CH. 1 ^ BLADE TIP L_ CH. 2 POSITION SENSOR #2 1 '\ I CH. 3 PHASE #3 SENSOR {p^iu ICH. m ^^ #m P LIGHT DATA DATA ANALYZER SOURCE LOGGER Figure 2. Optical Fiber Blade Vibration Monitoring System. RECEIVER ANTENNA '0 DATA ANALYZER TELEMETER Figure 3. Telemetry System. Turbine Aerodynamic Test In order to verify the turbine aerodynamic performance for each stage, the following tests were carried out using special test rigs. - The stage averaged loss coefficients were measured in a two dimensional cascade test by varying mach number and incidence angle. - The engine pressure ratio is largely dependent on the flow coefficient of the row 1 vane nozzle, so an annular cascade test using a scale model of the assembled row 1 vanes was carried out to determine the flow coefficient. Figure 4. Model Test Rotor. 3

4 Z W U u_ W "I DESIGN EFFICIENCY ZDESIGN PRESSURE RATIO 1-1.5% Stop Valve 1r Flow Meter Vaporizer Storage Tank -_^ '_ LPG Heater -DFlow Controll Valve Fuel Pilot Line Combustor Main t /^ j Cylind Emissions Instrumentation Emission Sample Test Cell Ca lind ersgas Exhaust Flow Controll Valve \ PRESSURE RATIO Figure 5. Turbine Row 4 Model Test. - fl Flow Throttle Valve I/Exhaust Water Quench DrFExhaust Pressure Controll Valve Combustion Test Two types of combustors were used for the shop test: a diffusion type, which was similar to the Westinghouse W50105 standard combustor, and MHI's advanced premixed type combustor for distillate oil fuel. Prior to the shop test, basic characteristics of both combustors such as flame propagation, exhaust emission, pattern factor, combustor wall temperature, dynamic pressure oscillation, etc. were checked in both atmospheric and high pressure tests, and if necessary, those combustors were modified to achieve the design target. Figure 6 shows the high pressure combustion test facility. In addition to the above test, mechanical vibratory tests, a flow visualization test around the combustor, and acoustic resonance tests were conducted to assure the reliability of the combustion system. Turbine Cooled Parts Heat Transfer Test Many advanced cooling technologies are incorporated into 501F hot parts to maintain the metal temperatures within desirable levels. Some of these technologies have already been utilized in MHI's advanced 13MW high temperature gas turbine MF111, and over hours of MF111 operating experience showed the benefit and reliability of those technologies. Figure 7 shows the comparison of cooling design between MF111 and 501F. In order to verify the effectiveness of cooling technologies which are unique to the 501F, such as 8 rows of pin fin cooling in the stage 1 vane segment, and shower head cooling for both rotating blade and stationary vanes, scale model tests were carried out. These test results were incorporated into the cooling design of 501F hot parts. Prior to the shop test, the cooling effectivenesses of the final configurations of both row 1 vanes and blades were confirmed in hot cascade tests. In these tests, prototype vanes and blades were positioned at the downstream end of the test combustor to simulate the actual engine operating conditions. Metal temperatures at various locations in the vanes and blades were measured and confirmed to compare favorably with the design allowables. Flow Meter SHOWER HEAD Air Source Compressor ROW 1 VANE FILM _FILM FILM ROW 1 BLADE FILM ' PIN FIN SHOWER HEAD O ^I ou p FILM PIN FIN ; b D FILM De PIN FIN FILM b 7 AIR _'^p LINSERT p p AIR AIR 30MW Two Shaft Gas Turbine Figure 6. Schematic of Combustion Test Facility. Q 4 O O O AIR o Figure 7. Cooling Scheme for 501F and MF

5 SHOP TEST PROGRAM The objective of the full load shop test was to verify the following characteristics as well as develop the optimum setting schedules for system components. 1. Starting characteristics - Confirm characteristics including light-off, acceleration, vibration, and surge margin. 2. Performance - Verify individual compressor and turbine as well as overall gas turbine performance. Parameters included airflow, power output, heat rate and exhaust temperature. 3. Exhaust Emissions - Emission testing included sampling for nitrogen oxides (NOx), nitric oxide (NO), carbon monoxide (CO), unburned hydrocarbons (UHC), Bacharach smoke number (BSN), carbon dioxide (CO 2 ), and oxygen (0 ). 4. Hot Parts Metal Temperatures - Confirmed that the hot parts metal temperatures were below the associated allowables at 1260 C (2300 F) RIT during full load operation. Components monitored include combustor baskets, combustor transitions, turbine vanes and blades, and turbine row 1 ring segment. 5. Mechanical Characteristics - Vibratory stresses of the compressor and turbine blades, bearing temperatures, casing temperatures, and disc cavity temperatures were monitored continuously during the test. In addition, axial and radial growths were monitored at strategic locations in the engine to verify design calculations. The major features of the shop test facility and engine installation are listed below. 1. The prototype 501F engine was coupled with a 162MVA generator. 2. All the auxiliaries associated with the test were shop facilities, including the starting system, lube oil system, coolers, and inlet and exhaust ducts. 3. Distillate oil was used as the fuel. 4. Two types of combustors were used. A diffusion combustor, similar to the W501D5, was used for initial start up and a pre-mixed combustor was used for rated operation. 5. The gas turbine and generator were installed in the test stand without packaged auxiliaries. 6. The control systems and supervisory instrumentation were shop available equipment. 7. The compressor air supply ducting system employed a bell-mouth inlet to measure air flow. 8. The electrical power generated was absorbed by a water rheostat with cooling towers. Figure 8 presents an overall general arrangement of the test facility, showing the major components: gas turbine, generator, exciter, starter, G/T control room, special instrumentation room, cooling air cooler, water rheostat, and air intake and exhaust stacks. The gas turbine generator was a 3 phase cylindrical synchronous alternator rated at 162,000 KVA. The starting system included a 1450 kw (1945 HP) electric motor. Monitoring System Durino Enoine Operation As mentioned previously, in addition to the supervisory instrumentation, more than 1500 special instrumentation points were applied to the engine during the full load shop test. Included were advanced instrumentation systems such as an Accufiber GENERAL ARRANGEMENT 1. GAS TURBINE 7. AIR COOLER 2. GENERATOR 8. TOWER 3. EXCITER 9. AIR INTAKE TOWER 4. STARTER 10. WATER RHEOSTAT 5. G/T CONTROL ROOM 11. EXHAUST TOWER 6. SPECIAL INSTRUMENTATION ROOM Figure 8. General Arrangement of 501F Shop Test. probe for measuring turbine inlet temperature, an optical pyrometer for monitoring turbine row 1 blade metal temperature, and an optical fiber for compressor blade vibration monitoring. A summary of the special instrumentation is shown in Figure 9. All measured pressure data were converted to electric signals through scani-valves and stored in a data logger. Dynamic pressure fluctuation and vibratory stresses were analyzed using an "FFT" (Fast Fourier Transform) analyzer with the frequencies and amplitude monitored during "real time" with the engine operating. Data critical to the continued operation of the engine, such as metal temperatures of hot parts and cavity temperatures, were also monitored on computer display together with associated alarm limits. Turbine inlet temperature of the operating engine was calculated from measured data using a heat balance calculation program. The required data for this calculation was automatically transferred from the data logger during engine operation. The following information was obtained with the engine monitoring system during the shop test. PERFORMANCE - Air flow, inlet temperature and pressure, exhaust temperature and pressure, fuel flow, generator output, compressor surge margin and stage efficiency, turbine stage and diffuser efficiency. METAL TEMPERATURES - Combustor basket, transition piece, row 1 turbine blade, row 1 through 4 turbine vane segments, row 1 ring segment, bearings, outer casings, blade rings, exhaust cylinder. STRESS/VIBRATION - Compressor blades and diaphragms, combustor baskets, transition pieces and associated supports, turbine blades, exhaust struts. In addition to casing vibration, both lateral and torsional rotor vibration were monitored.

6 (A) PERFORMANCE (B) METAL TEMP. (C) STRESS/VIBRATION (D) OTHERS AIR FLOW INLET TEMP. & PRESS EXHAUST TEMP. & PRESS FUEL FLOW GENERATOR OUTPUT COMPRESSOR (SURGE MARGIN (STAGE EFF. TURBINE (STAGE EFF. (DIFFUSER EFF. 8 COMBUSTOR BASKET 9 TRANSITION PIECE 10 TURB. ROW 1 BLADE 11 TURB. ROW 1-4 VANE 12 BEARING METAL 13 OUTER CASING 14 INNER CASING 15 EXHAUST CYLINDER 16 COMPRESSOR BLADE 17 COMPRESSOR VANE 18 COMBUSTOR BASKET 19 TRANSITION PIECE 20 TURBINE BLADE 21 ROTOR VIB. 22 CASING VIB. 23 ROTOR TORSIONAL VIB. 24 AIR NETWORK FLOW TEMPERATURE PRESSURE 25 TRUST LOAD 26 EXHAUST EMISSION 27 ROTOR/CASING EXPANSION 28 NOISE 29 LUBE OIL TEMP. Figure F Prototype Special Measurements. OTHERS - Thrust load, cooling air flow network, mechanical loss, air and gas temperatures of various cavities, exhaust emissions, rotor/casing displacement, noise level, and lube oil flow and temperature. TEST RESULTS The test program results are summarized below for the areas of starting and acceleration, overall performance, combustion emissions, hot parts temperatures, and vibratory stresses. Starting and Acceleration - The shop test starting schedule included ignition at 610 RPM, starter motor disengagement at 2400 RPM, and bleed valve closure at 3310 RPM with the IGV position held constant at 19 degrees. The elapsed time from starting button to synchronizing speed was about 20 minutes. At ignition speed, two combustors located at the bottom of the engine were ignited. Cross-flame tubes produced complete ignition in 40 to 50 seconds. Compressor rotating stall was cleared at approximately 2000 RPM. Throughout the starting sequence, compressor operating characteristics were very stable, thus indicating sufficient margin against surging during starting. When the starting motor was disengaged, the responses of exhaust gas temperature and engine speed were monitored to confirm that the engine could easily accelerate from 2400 RPM without assistance. Overall Performance - Performance data measured during the full load shop test were analyzed and corrected from shop test conditions to standard ambient conditions. The results show that the measured power output and exhaust gas flow exceeded the predicted values by more than 2%. In addition, the heat rate was slightly better than predicted and the exhaust gas temperature was higher than the predicted value by approximately 10 C (18 F). When the performance values shown in Table 1 were developed, some margin was incorporated. It has now been verified that measured performance exceeded the predicted values. New performance ratings will be established following completion of a full shop test data evaluation. Table F Design Plant Performance. INITIAL MATURE POWER, NET KW 135, ,000 HEAT RATE, K/KW-HR 10,706 10,548, BTU/KW-HR 10,150 10,000 AIR FLOW, KG/SEC , LBS./SEC PRESSURE RATIO 14:1 14.2:1 EXHAUST TEMPERATURE, C F Combustion/Emission - Nitrogen oxides (NOx), carbon monoxide (CO), unburned hydrocarbons (UHC), and other emissions were measured for both the diffusion type and the premixed type combustors using oil fuel. When using the premixed type combustor, it was found that the setting schedules of inlet guide vane and bypass valve would affect the combustion stability significantly. Figure 10 shows the dynamic pressure fluctuation measured inside the premixed combustor. Stable combustion was assured throughout engine startup and operation by selecting the optimum schedule of IGV and bypass valve settings. Figure 11 presents the NOX emission level of the premixed type combustor compared with that for the conventional diffusion type combustor at dry conditions. The NOx level of the premixed type combustor was less than half that for the diffusion type combustor at full load conditions. Hot Parts Temperatures - Figure 12 and 13 present hot part temperatures measured at the 1260 C (2300 F) full load condition. Figure 12 shows metal temperatures for rows 1 and 2 vane segments at mid height normalized to the calculation results. The temperatures were obtained from thermocouples which were mounted on the surface of the vane airfoils. It was

7 confirmed that the measured temperatures were within an acceptable range of the expected values, thus the calculation techniques for the cooled vane designs were considered verified. Figure 13 shows the row 1 turbine blade metal temperature at 60% blade height. The temperatures presented in the figure were obtained through the use of a pyrometer and confirm an adequate design margin. 100 W m O 75 ALLOWABLE LIMIT PREMIXED TYPE Evaluation of hot parts data is continuing and will provide the basis for further design improvements, if so indicated. Vibratory Stresses - Figure 14 presents vibratory stresses as measured during the test along with corresponding design allowables. Vibratory stresses of other stationary components such as combustor transitions and tangential struts were also measured. All measured stresses are within the design allowables. V DIFFUSION TYPE 0 F- G N 50 0 Ẓ 25 u w W N O % LOAD Figure 10. Combustor Noise Level L/E PRESSURE SURFACE SUCTION SURFACE I Q LL LL 0. i-a = O 80 Hi_ ON Q V 60 1W W a ~ WZ y 40 K Oa Z Q x 0 Z W 20 i DIFFUSION TYPE PREMIXED TYPE FUEL ; OIL L/E PRESSURE SURFACE SUCTION SURFACE Figure 12. Row 1 and 2 Vane Metal Temperature. 0 W Cr % LOAD LOAD I- -j 101W Q ALLOWABLE LIMIT -4 0 W 0-50 d W a ~ f -250 LL -300 Figure 11. NOx Emmission. Figure 13. Turbine Row 1 Blade Metal Temperature. ti 7

8 tion system proved successful for oil firing, and mechanical characteristics, such as vibratory stresses of blades and diaphragms, thrust force, axial/radial growth, and bearing metal temperatures were confirmed to be within the design limits at various operating conditions. 39 SUMMARY Figure 14. Summary of Vibratory Stress. Overall, the 501F shop test was an outstanding success. Performance was better than anticipated at 100% load, as presented in Table I. Hot parts metal temperatures were verified to be consistent with design values. A starting motor of 145OKW (1945 HP) was verified to be adequate via successful starting and acceleration testing. The new pre-mixed combus- REFERENCES 1. Scalzo, A.., Holden, P. C., and Howard, G. S., "The Westinghouse W501D Combustion Turbine Engine", ASME Paper No. 81-GT-32 March Akita, E., et al, "Development and Testing of the 13 MW Class Heavy Duty Gas Turbine MF-111, "ASME Paper No. 87-GT Aoyama, K. and Mandai, S., "Development of a Dry Low NOx Combustor for a 120 MW Gas Turbine, "ASME Paper No. 84-GT Hendry, R. L., Pillsbury, P. W., "Commercial Demonstration of the DOW Gasification Process in an Integrated Combined Cycle Cogeneration Application, "Proceedings of the American Power Conference, Scalzo, A.., et al, "A New 150 MW High Efficiency Heavy-Duty Combustion Turbine", ASME Paper No. 88-GT Scalzo, A.., Antos, R.., and Fukue, I., "Operating Experience Complements New Technology in Design of Advanced Combustion Turbine", ASME Paper No. 88-PGC/GT Scalzo, A.., Howard, G. S., Holden, P. C., "Field Test of the W501D A 100 MW Combustion Turbine," ASME Paper No. 83-GT-174.