Patent GB-612721-A (GB)
Title: Improvements in combustion product power plant
IPC: F02C5/06
Filed: 1946-02-11
Abstract: 612,721. Gas turbines. BAILEY, R. W., and METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. Feb. 11, 1946, No. 33511/45. [Class 110 (iii)] [Also in Group XXVII] A plant in which one or more gas-driven engines are supplied with combustion products comprises a combustion product generator supercharged by a compressor in which the compression ratio is substantially independent of speed and one or more additional combustion product generators each drivably coupled to and supercharged by a compressor of the axial flow vane or centrifugal type, together with means for varying the number of generators with axial flow vane or centrifugal type compressors which are on load for the purpose of compensating for large variations of load while relatively small variations of load are compensated for by varying the speed of the combustion product generator supercharged by the compressor whose compression ratio is substantially independent of speed. A combustion product generator means an internalcombustion engine supercharged by an air compressor, its exhaust gases being used to drive a gas-driven engine. The gas-driven engine can be a turbine or reciprocating engine. The use of sliding vane type compressors and a rotary compressor embodying two rotors with mutually engaging lobes or spirals is referred to. In Fig. 1, a combustion product generator 1 having a piston type air compressor 2 and several combustion product generators (only two being shown), each having an axial flow vane compressor 10 deliver into a gas conduit 9 which supplies a gas-driven engine (not shown). For starting up the generators, the conduit 9 may be charged with air under pressure by a compressor 18 driven by a motor 19. When the plant is used to form part of a power plant according to Specification 459,365, the conduit 9 does not deliver direct to a gasdriven engine, but the gas will pass first to a steam generator. Shut-off valves 20 are provided between each generator and the conduit 9. The combustion product generators with axial flow vane compressors may deliver into the conduit 9 through non-return valves (not shown). The combustion product generator with the piston type compressor may have clutches arranged so that the piston type compressor can be cut out and an axial flow compressor included. Fig. 2 shows means for switching in or out a generator with axial flow or centrifugal compressor. The only parts of the generator shown are the inlet manifold 13 supplied by the axial flow or centrifugal compressor and the exhaust manifold 14. For starting combustion products are introduced into the inlet manifold 13 to raise the temperature sufficiently to enable the temperature at the end of compression to reach the ignition temperature of the fuel. The combustion products can be controlled by a hand-operated valve 26 or by a valve 28 controlled by the difference in pressure in the inlet manifold 13 and the exhaust manifold 14 by means of a piston 31. The piston 31 also controls a valve 22 which opens or closes the outlet from the manifold 14 to atmosphere. A valve 23 controls the supply of gas from the exhaust manifold 14 to the gas conduit 9. The valve 23 is operated by a piston 36 acted on on one side by the pressure in the manifold 14 and on the other side by the pressure in the main 9. Movement of the piston downwards brings about closing of the valve 22. A modification is described in which the valve 22 is operated by a relay device to give greater sensitivity and more power to operate the valve. The piston 31 may be replaced by a thermosensitive device and the valve 26 may be controlled thermostatically. Both the 'Valves 22 and 23 may be controlled by a relay. When the gas-driven engine is stopped, all the combustion product generators could be stopped, the main 9 being maintained charged by the air compressor 18, the requisite blow-off taking place at 16 under control of the valve 17. It may be necessary to raise the temperature of the air delivered by the compressor 18 sufficiently for the temperature of the gas in the main 9 to start a generator &c. This heating may be provided directly by burning fuel in the air delivered at 18. For starting up the plant the air delivered by the compressor 18 may be heated by an auxiliary heater. Fig. 4 shows an alternative form of plant. Combustion product generators (not shown), one of which is supercharged by an axial flow vane type air compressor and the other by a piston type compressor deliver through pipe 15 into a main 9. The main 9 supplies gases either to a chamber 74 in which additional fuel may be burnt or to a steam boiler 77 in which also fuel may be burnt, the final products leaving at 78. Fig. 4 shows the plant as it would be when ready to be charged for starting. A charging air compressor 18 is started and valve 80 opened so that delivery takes place both to a combustion chamber 74 and to the gas space of the steam generator. The delivery at 81 may be sufficient to maintain adequate circulation in the piping 9, 86, 87. If desired, a fan 88 may be brought into action. Fuel burnt in the chamber 74 or in an auxiliary combustion chamber 90 provides heat to raise the temperature of the circulating air. When a sufficient pressure and temperature is attained, a combustion product generator is started, preferably by a gas-driven engine such as a. gas turbine. When the combustion product generator is self-acting and delivering to the main 9, heating would be cut off at 74 or 90 and the valve 17 would be opened to blow off gas delivered by the generator started. The. blow-off may be provided for by a safety valve which may be placed in the main 9. When the combustion product generator is working, compressor 18 may supply air for operating valves, control gear, &c. Specification 602,573 also is referred to. The Provisional Specification states also that a gas turbine can be used for starting the generators with axial flow compressors, the gas generators with the piston type compressor supplying the gases for these starting turbines.