某大容量高参数机组锅炉末级过热器管失效分析

Analysis of Ruptured Finishing Superheater Tubes Failure on Supercritical Boiler

某600 MW超临界锅炉末级过热器发生爆管,采用化学分析、金相观察、扫描电镜、能谱分析等手段对爆管段进行了分析。结果表明,本次爆管性质为长时过热爆管,其主要原因为管段长时超温运行后,脆性的σ相等析出物导致管段脆化所致。建议通过内窥镜、割管等手段查找管子内部及联箱入口是否存在有局部异物堵塞情况,在该管壁上方调整温度测点位置或增加温度测点数量,加强对管段局部超温的监测,并严格控制锅炉运行温度,避免超温运行。

The finishing superheater tube in a 600 MW supercritical boiler is ruptured.The brust tube is studied by chemical analysis,metallographic analysis,scanning electron microscope.The results show that the tube burst is a long-term superheated tube burst,and the main reason is that the brittleσ-equivalent precipitates of the pipe section leading to the embrittlement of the pipe section after long-term over temperature operation.It is suggested to find out whether there are local foreign matters blocking inside the pipe and header inlet by means of endoscope and pipe cutting.It adjusts the position of temperature measuring points above the pipe wall or increases the number of temperature measuring points.It improves the monitoring of local over temperature of pipe section,and strictly controls the boiler operation temperature to avoid over temperature operation.