某锅炉高温汽包封头腐蚀减薄原因分析

Analysis of Corrosion and Thinning Causes for a High Temperature Steam Drum Head in Boiler

采用光学显微镜、扫描电子显微镜、能谱分析、硬度测试、化学成分分析等多种材料学分析手段并结合现场的实际运行情况对某锅炉汽包封头腐蚀减薄的原因进行了分析。结果表明:汽包封头材料的各项性能都正常,腐蚀与封头材料无关;介质水中存在溶解氧和硫酸盐类物质是汽包封头发生腐蚀的主要原因,高温加速了腐蚀进程;同时汽包结构设计不合理,使高温水汽直接对汽包封头进行冲刷,导致封头区域的减薄速度大于其他区域的。

By means of optical microscopy,scanning electron microscopy,energy spectrum analysis,hardness testing,chemical composition analysis and other means of material science analysis,combined with the actual operation situation on site,the causes of corrosion and thinning of a steam drum head were analyzed.The results show that properties of the material for steam drum were normal,so material was not the reason for corrosion of steam drum.The presence of dissolved oxygen and sulfates in medium water was the main reason for the corrosion of the drum head,and high temperature accelerated the corrosion process.The design of drum structure was unreasonable,so that high temperature water vapor directly eroded the head of drum,which resulted in the speed of thinning of the head area faster than that of other areas.