再热器、过热器减温水过量的分析与改造

托电厂四期8号锅炉实际运行中,由于长期存在再热器、过热器减温水过量的问题而给锅炉运行的安全性和经济性带来了不利影响,急需进行改造治理。对此问题进行了深入研究,分析根本原因为锅炉设计时对准格尔劣质烟煤的燃烧特性和高海拔地区煤粉燃烧特性认识不足,炉膛结构尺寸、辐射和对流受热面分配比例设计不合理,引起炉膛吸热量的不足,锅炉蒸发出力不足使得实际炉膛出口烟温高于设计值,致使减温水量偏大、排烟温度偏高。改造完成后锅炉运行稳定,过热器减温水平均下降100 t/h左右,再热器减温水量减少至0 t/h,取得了满意的改造效果。

Analysis and Reconstruction for Excessive Desuperheater Water and Dereheater Water

The desuperheater spray amount for each of the steam generator units(Unit No.7-8,2×600MW,Tuoketuo power generation Co.Ltd,Datang International Group) exceeds its designated value from the very beginning of being put into operation.The desuperheater spray amount reaches to 330-350 t/h at full load(100%THA),which is much larger than the designated value of 77.8 t/h.Some strategies,such as combustor retrofit and combustion tuning,had been done to the unit.However,the amount can’t be effectively moved down.This endangers the unit operation safely and economically.Based on the numerical simulation and heat balance analysis,strategies of combustor tuning and lower temperature heat exchanger reconstruction were presented to decrease the spray amount of superheater.The exchanger reconstruction was done for unit No.8.Unit performance tests before and after reconstruction indicates that the desuperheater spray amount and exit flue gas temperature decrease markedly,and unit efficiency increases obviously.This strategy also makes an integrative coal rate decrease of 4g/kW.h.