A method for utilising waste heat from exothermic chemical reactions

摘要

PICT:0848895/III/1 In exothermic reactions the hot gaseous or solid products are brought into indirect heat exchange with compressed air or other gas used as a reaction component, and the heated compressed air passes to a back pressure turbine which drives the air compressors and also, if required, an electric generator; a part of the warm exhaust air is returned to the reactor. In a suitable apparatus, air compressed to about 5 atmos. is fed from compressors 1, to a preheater 2, and heat exchanger 3 to which is fed indirectly the hot gaseous or solid reaction products of a pyrites roaster furnace 6. The hot compressed air expands and drives a back pressure turbine 4 which is coupled to the compressors 1 and an electric generator 5. Part of the exhaust air is fed to the furnace 6 and part to the preheater 2. The amount of air entering the furnace can be controlled in relation to the quality of the pyrites, whereby the SO2 content of the gaseous reaction product can be maintained at above 8% if necessary. A number of furnaces may be fed from the turbine. If necessary, an auxiliary furnace providing additional combustion gases may be used, and switched in automatically to maintain the turbine output of heated air.