300MW CFB锅炉低压省煤器设计方案优化及经济性分析

Design and Economic Analysis of Low Pressure Economizer of a 300 MW Circulating Fluidized Bed Boiler

针对某300 MW循环流化床锅炉排烟温度较高,排烟热损失较大的问题,提出在锅炉尾部烟道上加装部分低压省煤器,来实现降低排烟温度并回收部分烟气余热。结合等效焓降法与热平衡法对低压省煤器的设计方案进行优化,采用等效焓降法分析低压省煤器在其回热系统中5种设计方案的热经济性。结果表明:低压省煤器与6#低压加热器并联的连接方式热经济性最佳,机组效率可提高0.808%,标准煤耗可降低2.265g/(kW·h);且随着负荷的升高,热经济性逐渐提高。

For the reconstruction project of reducing exhaust gas temperature and using flue gas waste heat at 300 MW circulating fluidized bed boiler,the paper proposes that the low pressure economizer is placed on the boiler flue to achieve reduce exhaust temperature and recycle flue gas waste heat.According to the design data of 300 MW power generator unit,the calculation results are consistent both conventional heat balance method and the equivalent enthalpy drop method.The thermal economic are analyzed for 5kinds of design schemes of low pressure economizer in regenerative system.The calculation results show that the parallel connection mode of the low pressure economizer and 6#low pressure heater can reach to the best cost-effectiveness.The power generator unit efficiency can be increased by 0.808%,and the standard coal consumption reduced 2.265g/（kW·h）.When operating condition was changed,the amplitude of increasing for the themal efficiency was decreased,with the unit load decreasing.