Application and thermal economic analysis of plate low pressure economizer in flue gas waste heat recovery

Abstract

Low pressure economizer is an important equipment to reduce exhaust gas temperature and recover waste heat of flue gas in power plants. In this paper, the welded plate heat exchanger is applied to the field of low pressure economizer. The waste heat of coal slag and flue gas is utilized comprehensively to raise the boiler feed water temperature and reduce coal consumption. The thermal economy of plate economizer and finned tube economizer is analyzed by the equivalent enthalpy drop method. The results show that the plate economizer has obvious advantages under the same pressure drop and heat load. Compared with the finned tube economizer, the heat transfer coefficient the of the plate economizer increases by more than 50%, and the volume decreases by about 2/3. After installing the slag cooler, the heat consumption rate decreases by 119.7 KJ/kWh, and the coal consumption decreases by 4.68 g/kWh.