600 MW超临界锅炉末级过热器管泄漏失效分析

Analysis on Leakage Failure of Final Superheater in 600 MW Supercritical Boiler

通过对600 MW超临界锅炉末级过热器泄漏失效管样的试验分析,以及对锅炉系统末级过热器布置形式与结构等全面分析研究后认为,引起末级过热器管多次泄漏失效的主要原因是锅炉启停过程中以及运行工况急剧变化时,使管内氧化层大量脱落并堆积在弯头部位,造成流通截面积减小,在机组负荷增大、管子壁面热流密度增高时因过热而发生爆管。

The leakage-failure specimen of final superheater in 600 MW supercritical boiler was teasted and analyzed, and the layout and structure of final superheater were researched in detail. Based on these, the main cause of leakage failure is found, that is, the steam-side oxide scales exfoiate largely during the start-stop process or on rapid-change running condition, the exfoliation of these scales lodges in the lower tube bends of superheater pendants, leading to restriction of the steam flow, which can result in the explosion due to overheating when unit load and heat flux of tube increase.