超超临界锅炉屏式过热器失效原因分析

Analysis on Failure Cause of Platen Superheater of Ultra-Supercritical Boiler

某超超临界锅炉屏式过热器管在运行过程中发生泄漏,利用爆口宏观分析、化学成分分析、显微组织观察、力学性能分析等方法对屏式过热器失效管样泄漏原因进行了分析。结果表明:屏式过热器管子的爆管原因为短时超温爆管,在运行超温过程中管子组织的三角晶界处逐渐形成了蠕变孔洞,蠕变孔洞的聚集萌生形成微裂纹,当机组升至满负荷运行,由于高温高压的作用使得组织中微裂纹迅速扩展进而导致爆管。

The platen superheater tube of an ultra-supercritical boiler leaks during operation.This paper adopts macroscopic inspection analysis of the open seam,chemical component analysis,microstructure observation and mechanical property analysis to analyze the cause of failure tube leakage of the platen superheater.The results are shown as follows:The tube burst of the platen superheater tube is caused by short-term over-temperature.In the process of overtemperature operation,creep pores gradually form at the triangular grain boundary of the tube structure,and the aggregation of creep pores and the formation of micro cracks are generated.When the unit is operating at full load,the micro cracks in the structure expand rapidly due to the effect of high temperature and pressure,which leads to tube burst.