超临界锅炉管内氧化皮剥落的安全控制研究

Safety control research on scaling of oxide skin from tubes in supercritical boiler

为防止超临界锅炉管内氧化皮剥落而频繁出现的超温爆管事故,提出基于安全温度变化率的超临界锅炉运行控制技术。研究超临界锅炉管内氧化皮厚度与运行时间的关系,导出氧化皮剥落的临界温度变化率与运行时间的关系式。以某600 MW超临界锅炉为例,结合工程安全裕度,绘制不同运行时间、材料、温度下防止超临界锅炉管内氧化皮剥落的安全温度变化率控制曲线。研究结果表明:超临界锅炉的运行温度越高、运行时间越长,安全温度变化率就越小;应针对不同管材,采用基于最小安全温度变化率的均匀启炉、加速停炉、停炉吹管安全运行控制技术。

For the sake of preventing the accidents of bursted tubes caused by both supercritical boiler oxide skin spalling and over-temperature,the paper was aimed at developing an operation control technology for supercritical boiler based on safe temperature change rate.A relationship was deduced between oxide skin exfoliation ＇s critical temperature change rate and boiler ＇s run time after studying the relationship between oxide skin thickness in tubes of supercritical boiler and run time.A certain 600 MW supercritical boiler in China was taken as an example,for which control lines of the safe temperature change rate preventing the oxide skin in supercritical boiler＇s tubes from exfoliating at different run time,different materials and different temperatures were drawn on the basis of data on the engineering safety margin.The results show that there is a negative correlation between the safety temperature change rate of the supercritical boiler and both the operating temperature and run time,that the safe operation control technology saying ＂ starting the boiler uniformty＂,＂ shutting down the boiler acceleratively＂ and ＂ shutting down the boiler and cleaning tubes＂,which is based on the smallest safe temperature change rate,should be adopted for different pipes.