自然循环锅炉启停过程汽包壁温差大的原因分析及控制

The Reason and Control of Large Temperature Difference of Drum Wall During Start-Up andShutdown of Natural Circulation Boiler

目前,国内部分区域的主力发电机组锅炉仍然是亚临界自然循环汽包锅炉。自然循环汽包炉由于汽包自身壁厚和运行工况的变化,不可避免导致各点的壁温存在偏差。尤其在机组启停过程中,容易因为压强突然变化导致汽包壁温差增大并超过最大允许值,导致汽包出现裂纹或者变形等危害,严重威胁汽包的安全运行,缩短汽包的使用寿命。文章分析了某电厂300 MW亚临界自然循环锅炉启停过程中汽包上下壁温差偏大的原因,在机组启停过程的各个操作细节上着手制定详细的解决汽包壁温差大问题的控制对策,保障汽包的安全运行。

At present,the main generator set boiler in some regions of China is still the subcritical natural circulation drum boiler.Due to the change of the wall thickness of the drum iteslf and the operating condition,the wall temperature of the ntaural cycle drum furnace is inevitably deviated.Especially in the process of unit start-up and shutdown,it is easy to increase the temperature difference of the drum wall and exceed the maximumal lowable value because of sudden changes in pressure,resultign in cracks or deformation of the drum,which seriously threaten sthe safe operation of the drum and shortens the service life fo the drum.This paper focuses on the analysis of the reasons for the large temperature difference between the upper and lower walls of the drum during the start-up and shutdown of a 300 MW sub-cirtical natural circulation boiler in a power plant,and sets out detailed control countermeasures to solve the problem of large temperature difference between the drum walls ine ach operation detail during the unit start-up and shutdown process,so as to ensure the safe operation of the drum.