Coupled High-Low Energy Level Flue Gas Heat Recovery System and its Application in 1000MW Ultra-Supercritical Double Reheat Coal-Fired Unit

Recovering the waste heat of flue gas to reduce its temperature with avoiding low-temperature corrosion is an effective way to improve the economic efficiency of coal-fired power plant. A coupled high-low energy level flue gas heat recovery system was introduced in the paper. The inlet air temperature of air preheater and the temperature of turbine condensate can be increased by using this system. Thermal economy model of the system was built based on equivalent heat drop method. The system was successfully applied in 1000MW ultra-supercritical double reheat coal-fired unit in Laiwu Power Plant of China Huaneng Group, and the operation data showed the boiler flue gas temperature was not higher than 90° C, and the coal consumption was reduced by using the system. (CSPE)