COMBINATION STEAM-GAS POWER PLANT AND METHOD OF ITS OPERATION Russian patent published in 1998 - IPC

FIELD: power engineering; gas-and-steam turbine plants. SUBSTANCE: exhaust gases of gas turbine, after cooling in first gas-and-water heat exchanger, are directed partially into boiler discharge nozzles and partially, after cooling in second heat exchanger, into coal pulverization system. Coal dust of pulverization system and air after air heater are delivered into burners of steam boiler. Third gas-and-water heat exchanger and air heater are located in parallel gas conduits in tail portion of boiler unit. Flow of gases directed into coal pulverization system is cooled in second heat exchanger to minimum temperature of drying agent (determined from heat calculation of coal pulverization system-CPS, and consumption of drying agent for fuel drying is increased to maximum. Part of feed water flow by-passing entire group of high pressure heaters of turbine plant is used as cooling water for first and second heat exchangers. Air heater is installed in one of parallel gas conduits of boiler unit, and in second conduit, third gas-and-water heat exchanger is installed. Flow of full-flow condensate of steam-turbine plant is used as cooling medium in third gas-and-water heat exchanger. Part of full-flow condensate is taken out for this purpose from regenerative dust of steam turbine plant with bypassing of one or group of low pressure heaters. Distribution of flue gases between two parallel gas conduits (depending on relationship of gas-and steam turbine power in steam and gas plant and its operating conditions) is provided by means of control valve. Part of combustion products of gas turbine can be directed also into convection gas conduit of boiler before air heater and third heat exchanger. Fourth heat exchanger can be arranged in one of parallel gas conduits before third heat exchanger, being placed in series with first and second heat exchangers as to direction of cooling medium flow. First heat exchanger can be made steam cooled being connected in parallel with reheat duct of steam boiler. EFFECT: enhanced efficiency of coal combustion. 6 cl, 1 dwg