燃气-蒸汽联合循环电厂烟气余热回收系统研究

Research on flue gas waste heat recovery system in gas-steam combined cycle power plant

通过分析锅炉烟气余热回收的2个关键问题,提出了基于烟气余热深度回收的集中供热新流程。该流程一方面将吸收式热泵与低温热网回水2种技术结合,实现排烟的深度降温;另一方面采用烟囱与喷淋塔合为一体的紧凑结构,在有效克服烟气带来的露点腐蚀问题的同时,提高余热回收的可行性。以3台FT8-3机组联合循环系统为研究对象,设计了烟气余热回收机组(由水-水板式换热器与吸收式热泵两部分构成)。综合考虑余热回收的投资与运行成本,对不同排烟温度下新系统的关键参数进行了优化,指出实现小端差水-水板式换热是提高系统经济性的关键。

Analyses two key issues of the boiler flue gas waste heat recovery, puts forward a new process of district heating system based on the deep recovery of flue gas waste heat. In this process, on the one hand, adopts absorption heat pump and low-temperature return water of the heat network to realize the deep cooling of the exhaust smoke, on the other hand, combines chimney and spray tower as a compact structure, to overcome the dew point corrosion of flue gas and improve the feasibility of the waste heat recovery. Taking a combined cycle system with three F1-8-3 units as the research object, designs the flue gas waste heat recovery unit （contains a water-water heat exchanger and an absorption heat pump）. Considering the investment and operating cost of flue gas waste heat recovery, optimizes the key parameters of the new system under different flue gas temperatures, and points out that realizing the small temperature difference of the water-water heat exchanger terminal is the key to improve the economy of the system.