1025t/h CFB锅炉屏式过热器管失效分析

Failure Analysis on Platen Superheater Tubes in 1 025 t/h CFB Boiler

某1 025 t/h CFB锅炉屏式过热器管多次发生靠近水冷壁前墙位置的爆漏,采用宏观检查、化学元素分析、显微组织分析及显微硬度分析等方法对屏式过热器管爆漏原因进行了试验与分析。结果表明:屏式过热器结构应力在靠近水冷壁前墙部位的叠加、屏式过热器管固定块焊缝的焊接质量不良以及启停炉过程中的应力循环等原因综合作用,导致固定块角焊缝低周高应力疲劳断裂,裂纹扩展至管子致使屏式过热器管爆漏。

For the platen superheater of one 1 025 t/h CFB boiler, explosive leakage issues have occurred in the region near the front water wall for several times. In this paper, by using macro-examination, chemical element analysis, mierostructure and microhardness analysis, the main reasons for these issues are identified. It can be concluded from the analysis results that, the overlay effects of the mechanical stresses in the region near the front water wall, the weak welded joints of the fixed blocks as well as the boiler＇s start up-shut down cycles will cause high-stress low-cycle fatigue fracture in the fillet weld of fixed blocks. The subsequent crack propogation finally leads to the explosive leakage issues.