采用宏观观察、力学性能测试、金相检验、扫描电镜及能谱分析等方法对某锅炉水冷壁爆管原因进行分析。结果表明:爆口附近存在腐蚀减薄,管壁向火面结垢量较大,垢层底部有槽型腐蚀坑,金属基体发生严重脱碳,并伴有裂纹;结合实际运行状况,认为爆管的主要原因是凝汽器泄漏,导致不合格循环水进入锅炉水中,同时加药方式不当及定期排污不合理,造成水冷壁向火面内表面发生严重的垢下碱性腐蚀。最后提出一系列改进措施,以避免该类事故再次发生。

The causes of water wall tube burst of a boiler were analyzed by means of macroscopic observation, mechanical property test, metallographic examination, scanning electron microscope and energy spectrum analysis. The results show that there was corrosion thinning near the explosion port, a large amount of scaling on the fire surface of the pipe wall, a groove-type corrosion pit at the bottom of the scale layer, severe decarburization accompanied by cracks in metal matrix. Combined with the actual operation conditions, it was considered that the main reason for the tube explosion was the leakage of the condenser, which caused the unqualified circulating water to enter the boiler water. At the same time, the improper dosing method and the unreasonable regular sewage discharge caused serious under-deposit alkaline corrosion on the inner surface of the water wall to the fire surface. Finally, a series of improvement measures were proposed to avoid the recurrence of such accidents.