The American Society of Mechanical Engineers

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1 paper no. 56-GTP-4 Copyright 1956 by ASME The American Society of Mechanical Engineers 29 WEST 39TH STREET, NEW YORK 1 NEW YORK 6200-KW GAS-TURBINE-DRIVEN MOBILE POWER PLANT Z. Stanley Stys, Assoc. Member ASME Head, Mechanical Division Brown Boveri Corporation 19 Rector St., New York, N. Y. Contributed by the Gas Turbine Power Division for presentation at the ASME Gas Turbine Power Conference in Washington, D.C., April 16-17, (Manuscript received at ASME Headquarters February 22, 1956.) Written discussion on this paper will be accepted up to May 20, (Copies will be available until February 1, 1957) 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. ADVANCE COPY: Released for general publication upon presentation. Decision on publication of this paper in an ASME journal had not been taken when this pamphlet was prepared. Discussion is printed only if the paper is published in an ASME journal. Printed in U.S.A. Price: 50 cents per copy (25 cents to ASME members)

2 ABSTRACT It is amazing how wide the field of application of this comparatively new machine is, because actually only slightly more than a decade has passed since it made its debut in continuous commercial service, To name a few such fields: Plower generation, traction, aviation, ship propulsion, chemical industry, nuclear reactors, etc, Brown Boveri gas turbines are being used in many of these applications and recently our company also developed a mobile power plant driven by a gas turbine, The purpose of this paper is to describe the details of such units,

3 1o66 ' KW GAS-TURBINE-DRIVEN MOBILE POWER PLANT By Z. S. Stys INTRODUCTION Power shortage may result from a local disturbance caused by a disaster such as flood, hurricane, fire or war, Large power concentration also may be required for oil drilling, location of ore exploitation mines in places far from any energy source, construction of water dams, and so on. Finally, it may be required to perform a power-demand test in undeveloped areas, by building first an electrical distribution system which can be tied in to such a mobile plant, and the power-consumption chart of a certain new area made available immediately. These and other applications were the reasons for Comision Federal de Electricidad of Mexico's ordering three such mobile power plants from Brown Boveri, PROBLEMS ENCOUNTERED AND THEIR SOLUTION The main problem was to accommodate the maximum possible output in a permissible size railroad car. The large choice of available patterns of gas turbines and axial-flow compressors made it possible to use one of already proven design with these two basic components. The combustion chamber was located at an approximate 60-deg angle in order to shorten the distance between bogies. It seemed impossible to accommodate two separate pipes from the combustion chamber to the gas turbine and from the compressor discharge to the combustion chamber. The solution is shorn in Fig. 1. Here again, the design of the combustion chamber's inner and outer enclosure was based on the well-proven high-temperature alloymetal finned bricks, easily removable and accessible for inspection and replacement. The experience gained from design and operation of the gas-turbine-driven locomotive was of great help in designing the base, which in this case was the frame of the car itself. The SLA1 - Winterthur, built such a frame which will be shown later. Because of small blade clearances, the deflection of the portion supporting gas turbine and compressor, which has a length of about 20 ft, should not be more than 0.02 in. On the other hand, the axle pressure had to be kept to an admissible limit, which was prescribed as smaller than 50,000 lb/axle. The walking space around the machine inside the enclosure was eliminated by adding a collapsible outside structure on the car side, which can be closed during transport of the power plant, as can be seen in Figs. 2 and 3. The silencer and exhaust stack are also easible detachable. In the same illustration can be seen the second car which carries the distribution facilities. To permit the use of such plant in the different voltage areas, a large range of transformer taps has been provided; i.e., 13.8, 6.6, 4014, 2.L kv. The single line circuit diagram of the plant is shown in Fig. 4. The transformer and high-voltage cubicle are arranged in the center of the car as shown in Fig. 5.

4 Due to the large-diameter cable for connection to the exciter (because of high starting current) the starting battery was located in the car end close to the generator-exciter set. DESIGN AND CONSTRUCTION DETAILS Fig. 6 presents the cross section through the power-generating car. At the left is the tilted combustion chamber. The regulating fuel valves can be adjustable easily from the control room which is situated at the adjacent end of the car. A multistage axial-flow compressor is used to supply the compressed air to the combustion chamber as well as for gland sealing and cooling purposes. In the passage of the suction air, an oil cooler was placed to make the plant independent of water supply. Brown Boveri has operating experience with such coolers which originally were placed in the suction of the 5000-kw gas-turbinedriven generators, of which eight units have been built for Arabian American Oil Company and are located on the desert of Saudi Arabia. The generator cooling air enters through filters from the sides and is discharged upwards. In the passage of the exhaust gases a fuel preheater is located to heat the heavy crude to the required viscosity, The whole set (contrary to gas-turbine-locomotive practice, where all machines have separate bedplates) is erected directly on the car frame. The previously mentioned Aramco sets are of the same type of construction. Such arrangement allows very neat auxiliary piping layout as well as weight saving but requires close co-operation of machinery and car manufacturers. Sufficient expansion joints and other provisions were made to allow for high-temperature gradient due to the short (15 min) starting time from cold to full load. A reaction-type gas turbine with inherently high-efficiency blading was used for expansion of the gases. Location of the auxiliary equipment of the power car can be seen in Fig. 7, which presents semi-assembly of the unit lifted by the crane in Brown Boveri shops in Baden. To the left fuel tanks with corresponding fuel pumps are located. At the opposite end, the generator and exciter can be noticed (the exciter also serves as a starting motor). Fig. 8 shows the nearly completed assembly of the machines and auxiliaries. Special design of bogies was also applied to achieve vibration-free operation. By close observation, one can distinguish this detail which is an arrangement with a central bolt located between springs. The bolt can be screwed down to the rail to release spring tension and prevent the power plant from getting into harmonic vibration during operation of the gas turbine. The control room of the power car is shown in Fig. 9.

5 -3- The inlet temperature to the turbine is shown and recorded at the center gage. Also the speed of the set, starting current, as well as the motor current of the oil pumps, etc., are indicated. Several interlocks and their indicators showing completion or failure of certain operation are also brought out to the control room. It is very simple to provide for a master control switch, which would permit automatic starting of the set by simply switching from position to position. As to the distribution car as presented in Fig. 10, it is worth while to mention that provision is made for starting of the set. The necessary 250 kw for a period of about 5 min is supplied from a battery which, during this period is highly overloaded; however, it can be immediately recharged after start during operation. The battery is located at the left end of the car. At the extreme right corner a small 100-kw aircooled diesel engine is located to provide power for auxiliaries during the starting period - it also can be used as battery charger after long standstill of the plant. Fig. 11 shows the power car ready for operation, and Fig. 12 the whole plant including distribution car as it can be used in any location with railroad facilities. Finally, Fig. 13 presents the ready-to-go cars, which can be attached to any train and transported over standard gage tracks of any country. MAIN CHARACTERISTICS The plant was built to comply with the characteristics given in Table 1. Gas Turbine Table 1 Principal Characteristics of Plant Maximum continuous rating referred to generator terminals and 0.8 pf with an ambient air temperature of 68 F, kw 6200 Speed, rpm 3600 Thermal efficiency referred to generator terminals (including auxiliaries), percent 19 1 Temperature before turbine, deg F 1200 Fuel Bunker C oil (starting with diesel oil) Time for starting(approx), min Speed for ignition, rpm 1200 Generator Output at pf kw 6200 kva 7750

6 - 4 - Rated voltage, volts 0 OOOOOOO 6600 Frequency, cycles per sec 60 Speed, rpm 3600 Cooling-air quantity at 70 F and 14.4 psia, cfm (approx) Exciter-Starting Motor (DC) As starting motor: Rated output, kw 220 Voltage, volts 200 As exciter: Rating, kw 35 Voltage, volts lls Speed, rpm.. OOOOOOOOOOO Main Transformer Rating, kva 7750 Primary, kv 6.6 Secondary, kv 2.4, 4.16, 6.6, 13.8 Auxiliary Transformer Rating, kva. e 0 ************** 115 Primary, kv 6.6 Secondary, volts 380/220 As accessories were provided CT's and PT's as well as a high-speed three-pole airblast circuit breaker on the secondary side of the main transformer. Disconnecting switches, lightning arresters and voltage regulator were added as standard accessories. The diesel-electric auxiliary set consists of a 12-cyclinder, 4-stroke, SLM diesel engine rated 126 hp at 6000 ft above sea level, 1800 rpm and 100 F ambient temperature, and a generator rated at 112 kva. A cadmium-nickel accumulator battery is provided for starting the d-o motor which has a capacity of 400 Sh. Voltage at,discharge is about volts.

7 - 5 - The main dimensions and weights of the plant are as follows: Gas-turbine car length, about 70 ft Switch-car length, about 60 ft Weight of power car with fuel, 330,000 lb Weight of second car, 190,000 lb PUTTING UNIT IN OPERATION AND PERFORMANCE TESTS To convert from mobile to operating setup, the following instructions must be followed: Support bogies on the rails. Uncover roof opening; set down rail and ladder steps. Connect fuel lines. Erect noise dampers (not absolutely necessary). Ground cars. Set transformer on correct voltage and connect with local system. Connect high-voltage and auxiliary cables between cars. The starting procedure actually can be made fully automatic and full load can be achieved in about 15 min from cold. The sequence of operations is as follows: Start diesel motor set. Start oil pumps. Start d-c motor by connecting to the battery. At 20 per cent speed ignite. At about 50 per cent speed starting motor is out, Synchronize, Switch over auxiliaries on the auxiliary transformer. Cut out Diesel set. The whole procedure can be noted also from Fig. 14.

8 -6 - TEST RESULTS The entire plant was tested before leaving the builder's plant, with the following results (guarantee comparison): Guaranteed Measured Output,. kw Efficiency, per cent Air temperature s; deg F Air pressure, psia Temperature before the gas turbine, deg F The following readings also were taken during the test run and after evaluation these are: Output, kw Thermal efficiency (generator terminals(, percent Pressure ratio of blower ,55 Speed, rpm Thermodynamical stage efficiencies of gas turbine, percent Thermodynamical stage efficiencies of compressor, percent The noise level with the noise damper is as follows: Distance 120 ft, decibels 93 Distance 300 ft, decibels 80 Such noise level is regarded as usual traffic noise. The whole set was designed, built and tested in 16 months. Shipment from Bremen, Germany, to Houston, Tex, was made on the MS Amdyle and then by rail to Mexico City.

9 -7- CONCLUSION The tests, as noted, show that the unit is slightly larger than calculated. Efficiency is also slightly better than expected. These values are received with our standard operating temperature of 1200 F, a range in which our company has accumulated considerable operating experience. New metals are being tested in our laboratories continuously and new ways to raise the temperature without shortening the life of the gas-turbine blading and combustion-chamber liners or endangering the machine. We believe maybe soon the output and efficiency of such units can be increased appreciably by incorporating improvements based on our test results. From the operating experience of such plants, there arose the desirability of a third car, carrying ladders : tools, spare parts and also having living accommodations for the operating crew. If we also add a fuel car and a locomotive which preferably may be gas-turbine driven, we will have a totally self-contained "emergency power plant train', which can operate entirely independently and generate power even in the wildest and most devastated areas where, of course, a railroad siding is still available. We believe that this particular installation of the gas turbine will soon become one of its important applications, judging by the amount of interest this mobile power plant has created among our customers all over the world.

10 -8 Z. S. Stys CAPTION FOR ILLUSTRATIONS Fig. 1 Arrangement of compressor, gasp turbine and combustion chamber with interconnecting piping Fig. 2 Model of mobile power plant unit ready for transportation Fig. 3 Model of mobile power plant unit ready for operation Fig. 4 Single line electrical diagram Fig. 5 Arrangment of transformer and high voltage cubicle Fig. 6 Cross section through power generating car Fig. 7 Gas turbine unit with auxiliaries shown in workshops Fig. 8 Assembled group on bogies Fig. 9 Control room of the power car Fig. 10 Distribution car Fig. 11 Power car ready for operation Fig. 12 Complete power plant ready for operation Fig. 13 Power plant ready to change location Fig. 14 Starting diagram

11 Fig.1 Fig. 2 Fig.3 Fig. 5 Single-Line Electrical Diagram 1. Generator Main transformer Connection with the local system 4. Lightning arrestor Exciter (also starting motor) 1C. 6. Starting resistance Fig. 4 Battery Auxiliary transformer Diesel generator set Feed of the auxiliaries of the gas turbine Motor generator set for battery reloading. Starting battery of Diesel motor. Fig. 6 me/terms-of-use

12 6 24,1 TT T3 me/terms-of-use

13 Ar5 Fig.12 Fig.13 Start3uL,:agalln 1. Injection of the fuel 2. Starting motor out off n - Speed of the gas turbine,!)-- Temperature before gas turbine. I - Current of the starting motor II - Battery voltage. Flg.14