GB1415530A - Method of operating a gas turbine - Google Patents

Abstract

1415530 Gas turbine plant ENGELHARD MINERALS & CHEMICALS CORP 9 Nov 1972 [10 Nov 1971] 51855/72 Headings F1G and F1L A method of operating a gas turbine comprises partially oxidizing a carbonaceous fuel, which when burned with a stoichiometric amount of air has an adiabatic flame temperature of at least 3300‹F, and then effecting further oxidation of the fuel at a temperature of between about 1500 and 3000‹F whilst the fuel/oxidant mixture undergoes expansion in the turbine. In one arrangement a gas turbine plant comprises a centrifugal compressor 12 supplying air to a region adjacent mixing vanes 22 where a hydrocarbon fuel, e.g. propane or naphtha, is introduced via line 21, the fuel/air mixture then flowing through a pre-heater 25 to a combustion catalyst 30. The latter is of insufficient volume to cause complete oxidation of the fuel but further oxidation occurs as the mixture expands through the nozzles 31 and rotor 14 of a single or multi-stage turbine on its way to exhaust duct 24 and heat exchanger 25. Catalyst 30 is heated at starting by fuel injected through line 38 and ignited by igniter 36, a thermocouple sensing the catalyst temperature. The catalyst 30 and plant fuel may be as described in Specification 1395422 and the plant conditions such as oxidant/fuel ratio, mixture velocity &c. are generally as specified in that Specification or in Specification 1395986. Oxidation in the catalytic zone or in the turbine may take place with or without a flame. In a modification the initial partial oxidation is effected by spraying fuel into the combustion zone without the provision of a catalyst. In this case cooling air may be mixed with the products while avoiding substantial completion of the combustion process before the gases reach the turbine. The products in exhaust duct 24 may be still further oxidized by thermal or catalytic means to reduce atmospheric pollution.