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A Heat Integration System Based on Boiler-turbine Coupling for Large Scale Coal-fired Power Plants

In order to resolve the "energy grade mismatch"problem which is common during the heat and mass transfer processes of the boiler and the turbine in the conventional power plants, this paper proposed a heat integration system based on boiler-turbine coupling. Considering the energy grade change principles of the air preheating process on the boiler side and the regenerative process on the turbine side, the proposed system combined these two processes together creatively. By fully integrating the heat transfer process of working mediums such as flue gas, steam, feed water and air,energy cascade utilization of the air preheating process and the regenerative process was finally realized. Combined with the actual operation data of a typical 1 000 MW ultra-supercritical coal-fired unit, the heat transfer characteristics and energy-saving benefits of the heat integration system were analyzed in detail. Results show that the proposed system has excellent performance: comparing to conventional system, the power supply coal consumption of the proposed system reduces by 4.02 g/(k W-h), saving on 15.254 9 million CNY for coal investment annually.