超超临界锅炉水冷壁泄漏原因分析

Analysis of Leakage Reasons of Water Cooled Wall of USC Boiler

通过宏观形貌观察、金相分析、扫描电镜分析和硬度试验对某电厂4号锅炉泄漏的水冷壁过渡管样进行了泄漏原因分析。结果表明:过渡管发生泄漏的原因是过渡管的内壁坡口加工处存在凹槽,凹槽处应力集中较大,在结构应力和内压应力的作用下,裂纹从凹槽处萌生,在机组启停、运行和调峰过程中逐渐由内壁向外壁扩展直至泄漏。

By means of macroscopic examination , metallographic examination , SEM examination and as well as hardness tests , the analysis of the leakage reasons of water cooled wall transition tube were investigated. The results showed that the reason of the leakage of the transition is the existence of the groove in the inner wall groove processing area. The stress concentration is large in the groove. Under the effect of structural stress and internal pressure stress , the crack sprout from the groove , and gradually extends from the inner wall to the outer wall to the leakage in the process of unit start-stop , operation and peak regulation.