凝结水喷淋装置在分离式低温省煤器与暖风器系统中应用

Application of condensate spray device in separated system of low pressure economizer and air heater

针对凝结水喷淋装置工程应用少、系统设计和运行优化经验不足等问题,介绍了凝结水喷淋装置的设计特点、优势以及在分离式低温省煤器与暖风器系统中的应用。该分离式低温省煤器与暖风器系统中,凝结水经暖风器冷却后回水方式有2路,提高了系统可靠性和稳定性;经暖风器冷却后的部分凝结水通过喷淋装置雾化喷入汽轮机排汽管道后,可以冷却部分乏汽、降低背压、节省煤耗,降低部分7号低压加热器抽汽量,增加系统节能收益。以某600 MW空冷机组为例,对不同工况下凝结水喷淋装置的经济性进行了计算分析。结果表明:同一负荷下凝结水喷淋装置的总节煤量随着环境温度的升高呈现先升高后降低的趋势,且暖风器出口水温越低,喷淋装置节煤量越高;建议暖风器出口水温与空冷塔内乏汽饱和温度差值在5℃以上时投运凝结水喷淋装置。该机组实际工程中凝结水喷淋装置全年平均节煤量为0.141 g/(kW·h),静态投资回收期4.41年。

For the spray system,there is few engineering applications and the experience of system design and operation is insufficient.To solve these problems and promote the application of this technology,the design features,advantages and application of the spray system in separated system of low pressure economizer and air heater were introduced.In the separated system of low pressure economizer and air heater system,there are two ways to return the condensed water cooled by the air heater,which improves the reliability and stability of the system.A part of the condensed water cooled by the air heater is sprayed into the turbine exhaust pipe through the spray system,which can cool part of the steam in the cooling tower,reduce the back pressure,save the coal consumption,reduce the steam extracted from No.7 low pressure heater,and increase the energy-saving benefits.Taking a 600 MW air cooling unit as the example,economic analysis for the separated system under different conditions were carried out.The results show that,the energy conservation potential of the spray system increases at first and then decreases with the increasing ambient temperature at the same load.Moreover,the energy conservation potential increases with the decrease of the water temperature at the air heater outlet.It suggests that the spray system should be put into operation when the difference between the water temperature at the air heater outlet and the saturation temperature of the steam in the cooling tower exceeds 5℃.In the actual project,the annual average energy conservation potential of the spray system is 0.141 g/(kW·h)and the static payback period is 4.41 years.