对冲燃烧锅炉水冷壁高温硫腐蚀分析及防治

Cause analysis and countermeasures of high-temperature sulfur corrosion of water wall in an opposed firing boiler

在某超临界600MW机组对冲燃烧锅炉检修中发现,侧墙水冷壁存在严重的腐蚀现象。对该区域腐蚀进行检查和烟气氛围测试发现,腐蚀类型为高温还原性硫腐蚀,且侧墙中间区域腐蚀较为严重,其中侧墙壁面附近烟气中腐蚀性气体H2S的体积分数高达10-3以上。对此,设计了一套安装于燃烧区域侧墙水冷壁上的贴壁风系统,改造后A、B侧墙的H2S体积分数分别下降了83.20%和87.16%,A、B侧墙的O2体积分数分别提高了224.5%和155.3%。增加贴壁风系统可有效抑制侧墙还原性气氛的形成,从而控制了水冷壁的高温硫腐蚀。

High temperature corrosion occurred on water wall of a 600 MW unit opposed firing boiler.The corrosion inspection and flue gas atmosphere test indicates that the corrosion type was high temperature sulfur corrosion and the corrosion got more serious on middle part of the side walls.The concentration of H2 Sin flue gas was very high near the side wall surface,which reached higher than 0.1%.In order to control the high temperature corrosion,a type of closing-to-wall air device on the side wall was designed.The test results show that,after the transformation,the H2S concentration at side A and side B of the boiler reduced by 83.20% and 87.16%,respectively,and the corresponding O2 content increased by 224.5% and155.3%,respectively.Thus,the reducing atmosphere was alleviated near the water wall and the high temperature corrosion can be effectively controlled.