采用复合相变换热器技术回收CFB锅炉烟气余热

Recovery of waste heat of CFB boiler flue gas by compound phase changing heat exchanger

采用复合相变换热器(FXH)回收CFB锅炉尾部烟气余热,代替原汽轮机2#低压加热器抽汽加热凝结水,并利用Matlab软件对烟气余热系统进行了热力仿真计算。改造后的运行结果表明,锅炉排烟温度从150～155℃降低至120℃,节省的抽汽可增加发电量175.284×104(kW.h)/a,供电标煤耗降低1.323 g/(kW.h),锅炉热效率提高1.85个百分点,改造静态投资回收期约为2.3 a;FXH的进口烟气温度不宜超过150℃,所选燃煤的烟气露点温度在108～114℃较适宜。

The flue gas waste heat of CFB boiler was recovered by compound phase changing heat exchanger（FXH） to heat the condensate instead of 2^# low pressure heater of original steam turbine, and the thermodynamic calculation of flue gas waste heat system was simulated by Matlab software. The results showed that the flue gas temperature reduced from 150 - 155 ℃ to 120 ℃ , the saved extraction steam could increase electric generating power by 175.3 ×10^4（ kW · h）/a, the standard coal consumption rate of power supply reduced 1. 323 g/（kW · h）, the boiler thermal efficiency increased by 1.85 percent point, and the simple payback period was about 2.3 years. The flue gas temperature at FXH inlet was not suitable for exceeding 150 % , and the flue gas dew point for the selected coal should range between 108 ℃and 114℃.