GB748163A - Gas turbine plants - Google Patents

Abstract

<PICT:0748163/III/1> In a gas turbine plant burning a fuel containing substances liable to form harmful combustion products, the fuel is distilled and the lighter fractions are burnt in a combustion chamber before the turbine and the remainder in a second combustion chamber after the turbine and before a heat exchanger heating the air entering the first combustion chamber. In the arrangement shown, Fig. 4, the fuel is vaporised and the vaporised fuel which is thus freed from harmful constituents is burnt in the combustion chamber 145 arranged in front of the turbine 147 and the residue in the combustion chamber 152 which discharges through the heat exchanger 140 to atmosphere. The raw fuel is supplied through a pipe 101 to a collecting vessel 102 from which it is forced by a pump 104 to a nest of tubes 106 of a preheater 107. The preheated fuel then flows through a coil 111 in a heater 110, supplied with air by a blower 114 and heated by a burner 113. The heated fuel passes through a reducing valve 117 into the expansion chamber 118 of a vaporizing device 119 in which a sub-atmospheric pressure is maintained. The heavier fractions are collected in the bottom of the expansion chamber. The fuel vapour is led through a pipe 120 to the preheater 107 where it condenses and is then drawn off by a pump 121. Float actuated valves 155, 156 prevent the fuel levels in the preheater 107 and vaporizing device 119 from falling too low. An ejector 125 maintains the pressure in the chamber 118 below atmospheric. The condensed fuel vapour is supplied to the combustion chamber 145 and the heavier fractions are supplied to the combustion chamber 152. In a modification of this arrangement, the compressor 136 is formed in two stages with an intercooler between them and the turbine 147 is formed in two stages, one of which drives the compressors and the other supplies useful power. In this arrangement, the combustion chamber 152 and heat exchanger 140 is arranged in parallel with the turbine exhaust pipe from which the combustion air is supplied by a blower. Further the heat for the heater 110 is supplied by combustion gases extracted from the turbine inlet. The heat exchangers may be cleaned by injecting sand into the turbine exhaust gases.