摘要
某亚临界300 MW机组锅炉发生了水冷壁爆管事故。本文对水冷壁爆口的宏观特征进行了检查,采用光学显微镜对金相组织进行了分析,利用电子衍射能谱仪(EDS)、X射线衍射分析仪(XRD)对管内部垢层(腐蚀产物)的元素成分、物相组成进行了分析。结果表明,水冷壁爆口宏观特征表现为"窗口"状脆性断裂,向火侧结垢量较大,垢层底部金属管壁存在明显的腐蚀减薄现象,垢层底部金属发生严重脱碳,并伴有大量沿晶裂纹,该水冷壁管爆管由垢下氢腐蚀引起。为了保障该锅炉安全运行,提出对水冷壁管进行无损检测,更换水冷壁管,进行专门的查定试验有效降低水冷壁管内壁结垢速率,同时应加强水汽品质监测等建议。
Water wall tube burst occurred in a subcritical300MW unit boiler.To find out the reasons,the macro characteristics of the rupture area were examined and the material’s metallographic structure was analyzed by optical microscope,the energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD)were adopted to examine the scale(corrosion products)on the tubes.The results show that,the tube exhibited“window opening”brittle fracture,and thick scale formed on inner wall of the fire-facing side.The substrate under scale was obviously thinned by corrosion,and decarbonization and intergranular crack were evident at the base metal.The rupture failure was resulted from hydrogen corrosion under scale.To insure the unit operation safety,several suggestions were put forward,such as preventive measures including using nondestructive testing method to examine the water wall tube,changing tubes with defects,conducting examination test to effectively decrease the scaling rate of the inner wall of water wall tube,and enhancing the monitoring of steam water quality.
作者
刘锋
张贵泉
张祥金
胡杨
连卫
张兆
姚建涛
LIU Feng;ZHANG Guiquan;ZHANG Xiangjin;HU Yang;LIAN Wei;ZHANG Zhao;YAO Jiantao(Xi’an Thermal Power Research Institute Co., Ltd., Xi’an 710054, China)
出处
《热力发电》
CAS
北大核心
2018年第12期146-150,共5页
Thermal Power Generation
基金
国家自然科学基金项目(51401163)~~
关键词
垢下腐蚀
氢腐蚀
结垢
金相组织
物相组成
水冷壁
亚临界锅炉
corrosion under scale
hydrogen damage
scaling
metallographic structure
phase composition
waterwall
subcritical boiler
