Patent GB-935172-A (GB)
Title: Gas turbine installation comprising at least one mechanically independent useful power turbine
IPC: F02C9/50
Filed: 1959-09-10
Abstract: 935,172. Gas turbine plant; centrifugal compressors. R. POUIT. Sept. 10, 1959 [Sept. 23, 1958; April 21, 1959], No. 30974/59. Classes 110 (1) and 110 (3). This invention relates to gas turbine power plant of the type in which a compressor supplies air to a combustion chamber feeding a turbine driving the compressor and the turbine exhaust is fed to a separate independently rotatable power turbine and in which the combustion air before it is supplied to the combustion chamber is heated in a heat exchanger by the combustion gases flowing from the compressor turbine to the power turbine. The amount of heat transferred is controlled by regulating the air flow through the heat exchanger and a by-pass around it. According to the invention, in one aspect, the means for controlling the amount of heat transferred is operatively associated with means for controlling the fuel supply and means for controlling the amount of swirl at the inlet of the compressor in response to the temperature or pressure, or both, of the gas at one or more points in the plant. According to the invention, in another aspect, the plant comprises two compressors arranged in series driven by two turbines arranged in series and the combustion air is heated in a heat exchanger by the combustion gases flowing between the two turbines. An intercooler, in which the amount of cooling may be controlled, is provided between the compressors. The amount of intercooling is controlled so that in response to a reduction of fuel, the rate of heat exchange is increased and the amount of intercooling reduced. Air compressed in a low pressure compressor 3, Fig. 2, passes through an intercooler 9 to a high pressure compressor 5 and is then heated in a heat exchanger 8 by the exhaust gases of the useful power turbine 1 before passing through a further heat exchanger 16 to a combustion chamber 7 supplying hot gases to a high pressure turbine 6 driving the compressor 5. The turbine 6 may exhaust to the low pressure turbine 4 either through a reheat chamber 17 or the heat exchanger 16. Automatic valves 18, 19 enable one or the other of the paths to be put into service. The amount of cooling in the inter-cooler 9 is controlled by a damper 11 regulated by the pressure at the discharge of the compressor 3. Fig. 3 shows the embodiment in Fig. 2 in greater detail. The fuel supply to the combustion chamber 7 is controlled by a lever 27 which regulates the rack bar 25 of the fuel pump 20. The rack bar 25 is also controlled by the temperature at the discharge of the combustion chamber by a thermostat 34 and by the pressure at the discharge of the compressor 3 by a spring-loaded piston 44 acting through a cam 40. The fuel supply to the reheat chamber 17 is also controlled by the lever 27. During the first part of its movement the lever 27 only controls the pump 20. During the later part it controls both pump 20, 21. The output of the pump 21 is controlled by the thermostat 38 in accordance with the temperature at the discharge of the combustion chamber 17 and by the spring- loaded piston 45 in accordance with the pressure at the discharge of the compressor 3. A speed governor 46 acts on the pump 20 to maintain the speed of the turbine-compressor set 5, 6 within predetermined limits. The flow through the heat exchanger 16 and the by-pass 15 is controlled by a shutter 50 in accordance with the pressure at the inlet to the combustion chamber 7. In another embodiment, Fig. 4, air compressed in a compressor 3 is heated in a heat exchanger 8 by the exhaust gases of a useful power turbine 1 and then passes to a combustion chamber 180 either directly or through a heat exchanger 16 heated by the combustion gases passing from the compressor driving turbine 4 to the useful power turbine 1. A two-way gate valve 116 serves to divert at least a part or even the entire quantity of compressed air through the heat exchanger 16. The valve 116 is manually controlled by a handle 144. The control rod 129 has a cam 130 which actuates a rod 119 to control the fuel supplied to the combustion chamber 80 by the pump 100. The amount of fuel supplied is also controlled in accordance with the pressure at the discharge of the compressor 3 acting through a spring-loaded piston 152 and cam 151. The piston 152 also controls the amount of swirl at the inlet of the compressor by rotating a crank 12 which drives a worm-wheel 141 which in turn rotates a ring 140. The ring 140 engages the external rear edges of the flexible blades 132, the front edges of which are flush mounted in slots 136 in the hub 133 and in slots 137 in the cylinder 134. The output of the fuel pump 100 is also controlled by the temperature at the discharge of the combustion chamber 80 by the thermostat 122 and by the pressure at the discharge of the compressor 3 by the spring- loaded piston 125 acting through the cam 127. A lever 143 and link 119 co-ordinate the controls of the fuel supply and amount of swirl. Reference has been directed by the Comptroller to Specification 827,542.