Document RaL4GdRv9zDjKp6XwDqgKbY2n

By ROY E. BURRIS and B. G. HATCH Ga$ Turbine Department General Electric Company How G. E. Tests Gas Turbines Unlike the steam turbine, the gas turbine power plant must be assembled and test operated as a whole, including ail ac cessories. Here is how the General Electric Company solved new problems in developing test facilities for a new product TN THE DEVELOPMENT and J. manufacture of a new design of prime mover, such as the combustion gas turbine, one of the important technical problems to be considered is the matter of comprehensive tests before shipment. Consideration must be given to new test techniques, ade quate instrumentation to secure com plete data for engineering design and performance analysis, and flexibility to cope with new and unexpected problems. Space must be assigned and adequate manpower trained in the special techniques required. Con sideration must also be given to ex pansion to meet increased production requirements, and to provide for new designs. Unlike the- sam turbine, which receives its source of energy in the form of steam at a predetermined pressure and temperature, the com bustion gas turbine incorporates within its structure the combustion of fuel, the control and metering of this fuel, and the supply of the neces sary primary combustion air and secondary cooling air. Usually none of these components, with the possible exception of control and certain other accessories, are interchangeable between designs. Therefore again, unlike the steam turbine, each gas turbine power plant must be assembled and operated as a whole, including all its accessories. This imposes a severe problem on the manufacturer, since the assembly time of each unit, together with its required auxiliaries and accessories and piping would become a major problem not commensurate with modern production. In this article it is assumed that the reader is familiar with, and has access to, descriptions of the commercial types of combustion gas turbines. Commercially, three types are in cur rent production by the authors' com pany, all of the open-cycle design. The first is the 4800-hp simple cycle gas turbine, Fig. 2, intended for a 4500 traction horsepower gas turbine electric locomotive. (Ref. 1; refer ences at end of article) In this de sign, a 15-stage axial flow compressor delivers 80.000 cu ft of air per minute at approximately six atmospheres pressure directly to a combustion chamber system. Fuel is burned to raise the temperature of this air to approximately 1400 F, where it is passed into a two-stage impulse-type turbine, exhausting directly to at mosphere. No regenerators or heat exchangers are used in this cycle be cause of space limitations in the loco motive cab. The turbine is designed to use oil as fuel and the power de veloped by the gas turbine will drive four d-c traction type generators to power the locomotive. The same gen eral design has also been successfully applied to stationary power plants by the use of standard reduction gear and 3600-rpm a-c generators fo power generation. (2), (3) Early Test Stands In the development of the first ga turbine of this type, intended fo locomotive, a test stand was special! designed to simulate the structure c a locomotive. It consisted essentiall. of two 30 in. I beams mounted or. trunnions at either end, which repre sented the support of the locomotive trucks. The stand was purposely made flexible to obtain as nearly ae possible any expected reaction or effect on alignment of the gas turbine with its reduction gears and four dgenerators. This developmental stan was used for more than 700 hr c firing test on the first unit, and wt also used for two subsequent gas tu bines intended for power plant u stallation. However, it was not we suited for production testing. The first of the new-design con pound-cycle 5000-kw power gener tion unit (4) was also tested on a d velopmental stand, located in tr comer of the building near the initi locomotive test stand. This cor pound cycle gas turbine incorporat two stages of compression, repr October, 1952--POWER ENGINEERING--Chicago. Illinois PLAINTIFF'S EXHIBIT r Fig. 2. Generol Electric 4870-hp turbine for 4800-hp locomotive drive Fig. 3. Regenerative cycle gas turbine with independent shaft load turbine senced by a low-pressure compressor driven by a low-pressure turbine, and a high-pressure compressor driven by the load turbine. 'The intercoolers and the regenera tors are mounted in pairs on either side of the gas turbine. It is obvious that the cycle is too complex for mounting in a locomotive cab, as in the case of the simple-cycle turbine previously described. Test Problems The necessary pressurized air ducts, piping, lubricating oil and fuel piping and water cooling would render it almost prohibitive to assemble this type of gas turbine, piece by piece, on a factory test stand before ship ment. Actually the first three ma chines of this type were individually assembled and tested on the de velopmental test stand before the production test area was developed. Because this test stand was mounted partly on a cast iron factory floor, and partly on a reinforced concrete foundation, it was difficult to hold the component parts in alignment and to prevent leaks in the highpressure air piping. The General Electric Co. is at present manufacturing three types of gas turbines: The first is the 4800-hp locomotive power plant previously described, redesigned from the de velopmental model for repetitive Fig. 4. A General Bectrie Co. 5000-kw gas turbine power plant on permanent Factory test stand showing reduction gear, high-pressure compressor, turbines, ond low-pressure compressor, all without lagging quantity production. This simplecycle gas turbine is identical with the 3500-kw simple-cycle stationary gen erating unit. The second is a 5000-kw compound cycle gas turbine with regeneration and intercooling, essen tially identical to the developmental models, except for minor redesign. The third is a new design of a 5000-np regenerative cycle gas turbine (5), primarily intended for mechanical drive applications, but equally suit able for power plant installations when driving a geared a-c generator with direct-connected exciter. This 5000-hp class of gas turbine, Fig. 3, includes a large outdoor- mounted regenerator which forms the base of the exhaust stack, and there fore requires ducting of high-pressure air from the compressor to the re generator. This same air, after being heated by the waste heat of the ex haust, is ducted back to the six com 0 bustion chambers. A large exhaust duct takes the hot waste gases from October, 1952--POWER ENGINEERING--Chicago, Illinois 63 1 ! j iI i i i It l i ( * tne exnaust ot me gas turome to tn base of the regenerator, where, aft heating the compressed air, it is__ charged vertically through the stack; Fig. 7. Production model, 4870-hp got turbine locomotive power plont on permanent factory test jtond Production Test Area In entering a planned production! program, it was therefore found ex-T pedient to abandon the development1 test stands, and to erect permanent - test stands for each class of gas tur-. bine, each stand designed specifically for the cycle intended. Principal de-3 tails of these are shown in this article. * As the units are factory tested by running them under their own power, it is necessary to have complete start ing and supervisory control equip ment, Fig. 11, identical to that which will be used in the field installation -- on each test stand. In fact, each test stand is essentially a replica of the' final installation on customer's foun dation, plus the addition of special test equipment, Fig. 9. . For production test purposes, the t unit test stands have permanent " lubrication systems. This necessitates " separate testing of all unit lubrication * systems which will be shipped to __ purchasers, to insure proper piping : and operation. These tests are con- ; ducted in the main test area adjacent - to the test lube oil storage and filter- _ ing system. > In addition to testing the complete . gas turbine, all accessories must be pre-tested before being assembled with and installed on the gas turbine. To accomplish this, a special enclosed room is provided containing motor driven accessory test stands and all necessary indicating equipment. Dur- ' ing this pre-test it is necessary to open parts to make adjustments and settings. To avoid erratic operation which might be caused by dust and dirt normally present in a manufac turing plant, this room is pressurized with filtered air. Testing of the gas turbines is con ducted in the large factory building formerly used in steam turbine manu facture, which has since been con verted and equipped with new facili ties for gas turbine manufacture. Unit Test Stands Each test stand consists of an air filter house, intake and exhaust ducts, foundation blocking, air piping, lubri cating system, fuel system, control system, loading system and test instrumentation. Each filter house contains two calibrated flow nozzles for accurately determining air flow to the unit com pressors at existing ambient tempera ture and pressure conditions. Filters are protected by louvers to prevent clogging from snow during winter months. The inlet ducts and the por tion of the filter house back of the flow nozzles are constructed to be as airtight as possible, and are periodi cally calibrated to determine actual leakage. Filter houses are located on the building roof. Fig. 13, adjacent to the test area. All ducts are insulated to reduce 64 October, 1952--POWER ENGINEERING--Chicago, Illinois fig. 10. (At fight) First 5000-hp/3500-kw two shoft tegenerotive cycle got turbine on test stand without enclosing covers. Note control equipment, top right . *t*: af the noise level. The exhaust duct for the locomotive test stand is also .. -y-i "tTap--; lagged to keep heat transfer in the test area to a minimum -- the loco motive unit exhausts at about 800 F during the summer and the heat given off by about 30 ft of ductwork would make operation ' rather un comfortable, as the duct is directly over the control and instrument area. A transit-leveled cast iron " T " slot section floor is laid in the test area where the stands are located, to simplify anchoring foundation blocks. Foundation blocks are fabricated from steel plate and fastened to the floor with hairpin clamps, doweled in place and grouted in to avoid move ment from the forces involved. Every effort possible was made to design the blocking so that natural fre quencies would not coincide with run ning speed of the units. The 5000-kw compound cycle gas turbine. Fig. 5, consists of two com pressors, a turbine, a reduction gear, generator and direct-connected ex citer in addition to the stationary intercoolers and regenerators. The test stand for the rotating parts of this unit is made to hold each com ponent, assembled complete with bases. Alignment of components, Fig. 4, with each other and with the reduc tion gear is done with jack bolts at tached to the test stand. Dowel bush ings are used when doweling after the line-up is completed. This unit oper ates at constant speed and varying load as will be encountered in central station service. The simple cycle locomotive units are assembled on a line-up fixture, and the fully assembled unit is then swung onto the test stand for con necting to the reduction gear and loading generator. Proper footings and foundations are provided on the permanent test stand base, Fig. 6, to permit minimum alignment time with shims, as the locomotive gas turbine does not have its own rigid base, Fig. 7: The stand is equipped with a 4000-kw a-c generator and is practically identical with a stationary power plant installation. The unit is operated at variable speed and load to simulate locomotive operation. 5000-Hp Unit Because of the number of orders for this new 5000-hp regenerative cycle unit (which also may be rated 3500 kw when used with a power gen erator), two stands have been pro vided for this type of unit. One of the test stands, Fig, 8, is complete with reduction gear and 4000-kw a-c (Continued, on page 120) Fig. 11. Test stand for 5000-hp two shaft regen1_ erotive cycle gos turbine. Control panel, load v-' toble and temperature recording pgnel otjhe reor Fig. 12. One of the special manometer boards for making pressure measurements which is erected at each of the permanent gas turbine test stonds Fig. 13. (I to R) Filter bouses for test stands on roof of building. Exhaust stack stand, filter house and exhaust stock stand in process of erection I j October. 1952-POWER ENGINEERING--Chicago, Illinois 65