350 MW燃煤机组空气预热器压差大原因分析及对策

Cause Analysis and Strategy for Large Differential Pressure of Air Preheater in a 350 MW Coal-fired Unit

针对某350 MW燃煤机组空气预热器(简称空预器)烟气侧压差大的问题,对煤质、空预器冷端低温腐蚀、空预器吹灰及冲洗相关情况进行了分析,确认其原因为二次风暖风器出力不足导致冷端低温腐蚀。通过对二次风暖风器及疏水系统进行改造,提高了空预器冷端温度,并对机组经济性的影响进行了分析。结果表明:暖风器改造后空预器烟气侧压差恢复正常,解决了空预器冷端低温腐蚀的问题。

Aiming at the problem of large differential pressure at the flue gas side of air preheater in a 350 MW coal-fired unit, relevant information including coal quality, low temperature corrosion at cold end, soot blowing and flushing of air preheater was analyzed. It was confirmed that insufficient output of secondary air heater should be responsible for the low temperature corrosion of air preheater. Based on that, retrofit of secondary air heater and drainage system was carried out which led to the rise of cold end temperature of air preheater. Besides, an analysis of the influence on the unit economy was also conducted. The results show that after the retrofit of air heater, the differential pressure at the flue gas side of air preheater returns to normal level, and the problem of the low temperature corrosion at cold end of air preheater can be solved out.