电站锅炉低压省煤器进口水温及温升综合优化

Comprehensive Optimization of Inlet Water Temperature and Temperature Rise of Low Pressure Economizer in Utility Boiler

电站锅炉加装低压省煤器是深度降低排烟温度、利用电站锅炉排烟余热的有效途径,但降低排烟温度的幅度受到受热面腐蚀、减少汽轮机抽汽量、增加引风机和凝结水泵负荷、设备投资以及运行费用增加等因素的综合影响。以安全工作年限内的年平均收益作为指标,针对某典型600MW机组计算得到年平均收益最高时低压省煤器的优化设计参数:进口水温81.60℃,凝结水温升11℃,低压省煤器减少6号低压加热器抽汽,排烟温度由120℃降至94.19℃,安全工作年限8.387年,供电标准煤耗率降低0.818g/(kW·h),1.787年回收初投资。

Installing low pressure economizer is an useful way to deeply decrease the exhaust gas temperature and utilize utility boilers＇ waste heat, but reducing the scope of exhaust gas temperature is comprehensively affected by many factors, such as corrosion of heating surface, decreasing amount of extraction steam from turbine, additional load of induced draft fan and condensate pump, equipment investment, increase of operation cost and so on. For a typical 600 MW unit, this paper used annual average profit of low pressure economizer in safe working period as evaluation indicator and calculated optimum design parameters of low pressure economizer when annual average profit was the highest. Results shows that, inlet water temperature was 81.60 ℃, temperature rise of condensation water was 11 ℃, low pressure economizer decreased the extraction steam of 6th low pressure heater, exhaust gas temperature was reduced from 120 ℃ to 94.19 ℃, safe working period was 8. 387 years, power supply coal consumption rate was reduced by 0. 818 g/（kWoh）, and initial investment recovery period was 1. 787 years.