135MW机组锅炉排烟温度高的原因分析与治理

Analysis and treatment of high exhaust gas temperature for 135 MW boiler

针对SG420/13.7-M751型锅炉与首台国产135 MW反动式汽轮机配套投运后排烟温度高出设计值21℃的问题,从运行方式的角度分析并找出了排烟温度高的直接原因是锅炉一次风及制粉系统掺冷风,通过对比试验和理论计算发现一次风系统掺入的冷风和磨煤机进口混入的冷风分别占锅炉总风量的9.0%和3.9%,致使流经空气预热器的风量减少,引起排烟温度分别升高15℃和5℃。通过进行以一次风系统停止使用压力冷风为目的燃烧器改造,结合运行方式优化措施,使排烟温度降至设计值,实践结果表明这是简捷而有效的治理方式。

The actual exhaust gas temperature of boiler SG420/13.7-M751 was 21℃ higher than the design value when it was operated with the first homemade 135 MW reaction steam turbine. Based on the analysis of operation mode, the immediate cause was determined and presented in this paper, that is, the cold air was mixed into the boiler primary air system and coal pulverizing system. According to the experiments and theoretical calculation, the cold air mixing rate in primary air system and the inlet of pulverizer are 9.0% and 3.9% respectively, as a result, the air flowing through air preheater reduces and the exhaust gas temperature increases by 15℃ and 5 ℃ correspondingly. Combustion system reconstruction, optimizing operation, can decrease the flue gas temperature to the design value by stopping the pressurized cold air in primary air system. The practice indicates that all these methods are feasible and effective.