Abstract: A surplus heat recovery system with water heat medium was set up to recover heat in flue gas from the furnaces of disproportionation unit in SINOPEC Yangzi Company. The water supply to the medium-pressure boilers was used as heat carrier, the heat recovered from flue gas was used to preheat the combustion air, and two heat exchangers were involved in realizing the heat exchange among flue gas, water and air, so as to reduce the temperature of exhaust flue gas and to enhance the thermal efficiency of furnaces. After revamping, the thermal efficiency of furnaces was increased from 85.0% to 91.4%; an economic effect of 5.7172 million RMB was obtained annually.

Key words: heater, disproportionation unit, water heat medium