GB608776A - Improvements in or relating to gas turbine plants - Google Patents

Abstract

608,776. Gas turbines. SULZER FRERES SOC. ANON. Jan. 1, 1946, No. 43. Convention date, Nov. 3, 1945. [Class 110 (iii)] In a gas turbine plant of the type in which air flowing in a circuit is compressed, heated in an air heater and expanded in a turbine which drives the compressor before returning to the inlet of the compressor and in which some of the air is continuously taken from the circuit to serve as combustion air for the air heater, the exhaust gases from which are used in a useful output gas turbine, the make-up air, to replace that withdrawn from the circuit, is supplied either by a charging air compressor driven by a turbine actuated by air from the circuit or through a pipe byepassing the charging air compressor, control valves being arranged so that when the byepass is open the air supply to the charging air compressor turbine is closed and vice versa. At normal loads the charging air compressor and its associated turbine are inoperative, being brought into operation only when high output is required. Part of the air from a compressor 1 passes through a pipe 2, heat exchanger 4 and pipe 5 to a heat exchanger 7 arranged in an air heater 6 before passing to a turbine 9 driving the compressor 1. The exhaust from the turbine 9 passes back through the heat exchanger 4 to the inlet of the compressor 1. The remaining part of the air from the compressor 1 passes through a heat exchanger 26, where it is heated by the exhaust gases from the turbine 24, to the combustion space 20 of the heater 6 where fuel from a pipe 21 is burnt. The combustion gases from the heater 6 pass to a turbine 24 driving through gearing 32 a variable pitch propeller 33. The air withdrawn from the circuit through the pipe 3 may be replaced by atmospheric air supplied through the pipe 29 or by the charging air compressor 30 driven by the turbine 11 supplied with heated compressed air from the heat exchanger 7. At normal load, the valves 35, 36, 37 and 38 are in the position shown, make-up air is supplied through the byepass pipe 29 and the hot air supply to the turbine 11 is shut off. Under overload conditions, the valves 35 and 38 are closed and the valves 36 and 37 are opened and make-up air is supplied by the compressor 30. The pipe 39 which byepasses the high pressure stages of the turbine 24 is open at low loads to increase the area of flow so that pumping of the compressor 1 is avoided. The turbine 24 may be arranged in two stages which are independently connected to the propeller 33. The high pressure stage, which is byepassed by the pipe 39 being connected to the propeller through a clutch which may be a hydraulic coupling so that at low loads it may be disconnected and windage losses avoided. Two modifications, in which the turbines 9 and 11 are arranged in series instead of in parallel as shown, are also described. In one modification, the turbine 9 is the high pressure turbine and in the other the turbine 11. In both these modifications, the piping and valve arrangements are such that the turbine 11 can be put in and out of operation.