GB870589A - Improvements in and relating to gas turbine plants - Google Patents

Abstract

870,589. Gas-turbine plant. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Sept. 20, 1957 [Sept. 21, 1956], No. 28944/56. Class 110(3). A gas-turbine power plant comprising a combustion chamber at least one compressor in the air supply to the chamber, at least two turbines arranged in series supplied with working fluid by the chamber and with one of the turbines, the inlet pressure of which is below the highest turbine pressure stage, connected to a power output shaft and another of the turbines to the compressor or one only of the compressors, has an auxiliary turbine to aid the compressor driving turbine. The auxiliary turbine may be connected to the compressor shaft by a detachable coupling and temporarily supplied with working fluid or may be supplied with working fluid from two sources. In the arrangement shown, Fig. 1, atmospheric air is compressed in a low-pressure compressor 2, cooled in an intercooler 3, further compressed in a compressor 4 and then led to a combustion chamber 5. The combustion gases pass first to a turbine 6 driving the compressor 4, then to a turbine 7 driving an alternator 8 and then to exhaust through a turbine 9 driving the compressor 2. Additional power is supplied to the shaft of the low-pressure compressor 2 when required by means of an auxiliary gas turbine. The gas turbine comprises a compressor 10, combustion chamber 11 and a turbine 12 driving the compressor and through reduction gearing 13 and releasable coupling 14 the compressor 2. The fuel supply to the combustion chamber 11 is best controlled by hand. In a modification, Fig. 2, atmospheric air is compressed in a compressor 102 then heated in an exhaust gas-heat exchanger 105 and fed to a combustion chamber 108. The combustion gases are fed first to a turbine 109 driving the compressor 102 and then to a turbine 110 driving a ship's propeller through reduction gearing 111. The exhaust from the turbine 110 flows through the heat-exchanger 105 and boiler and superheater 112, 113 to atmosphere. A separately fired boiler 114 is also provided. The steam is utilized in two turbines. The first 115 drives an auxiliary generator 116 through reduction gearing 117 and the other 119 assists the turbine 109 to drive the compressor 102. The steam supply to the turbine 115 is controlled by the speed governor 118 and that to the turbine 119 by a pressure regulator 120 which maintains the live steam pressure constant. One or more hand admission valves are provided. When the ambient air temperature increases, the auxiliary turbine 115 is shut down so that the steam supply to the turbine 119 is increased, so as to enable the power output of the gas-turbine plant to be maintained. At still higher ambient temperatures the steam boiler 114 is started up. The gas turbine set is started by the turbine 119 supplied with steam from the boiler 114. In a modification, Fig. 3 (not shown), the turbine driving the auxiliaries is placed in parallel with the high pressure stages of the turbine driving the compressor. In this arrangement the separately fired boiler is supplied with combustion air either by a fan or by the exhaust gases of the power turbine. The exhaust gases from this boiler are led into the gas-turbine exhaust after the heat-exchanger. In another modification, Fig. 4 (not shown), the steam generated in the separately fired and exhaust gas boilers is normally used in a main power turbine. For starting and for supplying additional power to the compressor, steam is admitted to a turbine on the compressor shaft. If there are several compressors, additional power may be supplied to the low-pressure compressor only or to all of the compressors. When a steam turbine supplied with steam from an exhaust gas boiler is used, the steam may in normal service supply steam to the turbine connected to the compressor shaft. Additional power is then obtained by steam from an external source.