GB693616A - Improvements in or relating to internal combustion gas turbines - Google Patents

Abstract

693,616. Thermal regenerators and recuperators. POWER JETS (RESEARCH & DEVELOPMENT), Ltd. Feb. 1, 1951 [Dec. 5, 1949], No. 31205/49. Class 64 (i) [Also in Group XXVI] To enable a fuel of low calorific value, such as a gaseous mixture of coal dust dispersed in air or methane in mine ventilating air, or solid fuel, e.g. peat saturated with water or sewage sludge, to be used in a gas turbine plant, the combustible gas mixture or combustion air is heated in a regenerative type heat-exchanger before its entry into the combustion chamber by the combustion gases prior to their entry into the turbine. In the arrangement shown, the compressor 1 feeds air to a gas turbine 3 through a heat-exchanger 2 heated by the turbine exhaust gases and a further regenerative heat-exchanger 5. The heat-exchanger 5 is arranged to add sufficient heat to the air for combustion when using solid fuel and to the fuel-air mixture when using a gaseous fuel so that the combustion is self sustaining. This heat-exchanger comprises two parts 7 and 9 with a combustion chamber midway at 8 and changeover valve gear 6. The arrangement is such that, at one stage, the incoming air-fuel mixture passes through part 7, which has been previously heated, to the combustion chamber 8 where it is burnt and then passes through the part 9 to the turbine 3. When the temperature of the part 7 has fallen sufficiently, the valve gear 6 is operated so that the air-fuel mixture passes through in the reverse direction, i.e. through the part 9 to the combustion chamber 8 and from this chamber through the part 7 to the turbine 3. When the temperature of the part 9 falls sufficiently, the valve gear 6 is again operated and the cycle repeated. Auxiliary fuel may be supplied through conduit 5a and valve 5b for starting purposes. The plant may be used to bum a solid fuel such as peat. In this case, the peat is comminuted and shredded and fed to the combustion chamber 8 and only the combustion air is preheated in the heat-exchanger 5. To avoid blocking the outlet side of the hea-texchanger with ash, a cyclone separator may be arranged at the outlet of the combustion chamber. If there is no risk of the ash impairing the efficiency of the heat-exchanger, the cyclone separator may be arranged at the outlet of the heat-exchanger to avoid damage to the turbine blades. An auxiliary heater may be arranged between the heat exchanger 5 and the turbine inlet to correct any temperature fluctuations. The regenerative heat-exchanger described may be replaced by one of the rotary matrix type. The matrix of the regenerative heat-exchangers may be constructed at least partly of combustion-promoting catalysts. This enables the size of the heat-exchanger 5 to be reduced. A further auxiliary combustion chamber may be arranged between the conduits 12 and 15 to bum an auxiliary fuel which may be of higher calorific value. According to the Provisional Specification, a recuperative heat-exchanger may be used.