660 MW超临界对冲锅炉低氮改造后水冷壁高温腐蚀治理

Treatment of High Temperature Corrosion of Water Wall after Low-nitrogen Transformation on 660 MW Supercritical Opposed-firing Boiler

针对超临界对冲燃烧锅炉在低氮改造后水冷壁两侧墙高温腐蚀加重的问题,分析了水冷壁高温腐蚀的原因及影响因素,全年平均S_(t,ar)约2.78%,入炉煤硫分高、低氮改造后水冷壁近壁面还原性氛围浓是水冷壁高温腐蚀加剧的主要原因,针对该问题实施了锅炉侧墙贴壁风技术改造。通过贴壁风调整试验,找出了最佳贴壁风开度。贴壁风改造后,改善了侧墙还原性气氛,H_(2)S体积分数能有效控制在200 ml/m^(3)以下,缓解了水冷壁管高温腐蚀速率,大大降低了水冷壁腐蚀爆管泄漏事故风险和换管检修成本,有利于机组的安全、经济运行。

Aiming at the problem of increased high-temperature corrosion on both sides of the water wall after the low-nitrogen transformation of the supercritical opposed-firing boiler,the reasons and influencing factors of the high temperature corrosion of the water wall were analyzed.The annual average St,ar is about 2.78%,the high sulfur content and low-nitrogen transformation are the main reason for the increase in high temperature corrosion of the water wall after the reformation.The technical transformation of the boiler side wall attached to the wall was implemented.The best air opening was found through the adjustment test.The reducing atmosphere of the side wall is improved after the wall air transformation.The H_(2)S volume fraction can be effectively controlled below 200 ml/m^(3),which relieves the high temperature corrosion rate of the water wall pipe,and greatly reduces the risk of leaking accidents of the water wall corrosion and pipe replacement and maintenance.The cost is conducive to the safe and economic operation of the unit.