国内燃煤机组锅炉完成超低排放改造后,锅炉水冷壁普遍出现不同程度的高温腐蚀,对冲燃烧锅炉尤为严重,严重威胁锅炉的安全稳定运行.为从根本上解决水冷壁高温腐蚀问题,提出一种防治对冲燃烧锅炉水冷壁高温腐蚀的气膜保护技术,运用数值模拟对锅炉运行时水冷壁附近区域的烟气成分进行模拟计算,以烟气中O2、CO和H2S组分的体积分数为主要研究对象,优化气膜保护喷口的位置、层数、垂直倾角和风量配比,并对比现场研究结果.数值模拟和现场试验结果均表明,应用气膜保护技术后,锅炉热效率和SCR脱硝反应器入口NOx体积分数变化较小,锅炉运行参数均正常,未对锅炉的正常运行产生不利影响.应用气膜保护技术后,水冷壁附近平均O2体积分数可达5.0%以上,较应用前提高5倍以上,平均H2S体积分数较应用前降低85%以上,可控制在100 μL/L以下,水冷壁附近区域的还原性气氛消除,腐蚀性气体体积分数显著降低,水冷壁高温腐蚀得到根本治理,锅炉运行安全性显著提高.水冷壁气膜保护技术对同类型机组锅炉水冷壁高温腐蚀的防治具有良好的示范作用.

贴壁风技术是缓解燃煤锅炉水冷壁高温结渣和腐蚀问题的有效措施,其原理是通过水冷壁上的空气喷口向结渣腐蚀严重区域通入贴壁风,以达到降低壁面温度、改善还原气氛的目的.在某超临界600 MW机组配套的对冲燃烧锅炉前后墙水冷壁上加装了3层贴壁风喷口,并开展了贴壁风空气动力场冷态工业试验和热态燃烧运行试验.结果表明:贴壁风气流可覆盖至侧墙中部位置,能够实现对炉膛易腐蚀区域的良好覆盖和吹扫;锅炉负荷为600、450、300 MW的工况下,贴壁风投运后水冷壁的贴壁O2体积分数较投运前平均提高至3.0％以上,贴壁H2S体积分数平均降低80％以上,且均在200×10–6以下.水冷壁的高温腐蚀问题可以得到有效防控.

Directing against the problems existing on supercritical 600 MW units no.3 and no.4 in Qinbei Power Generation Co Ltd ever since begining of putting them into operation,such as over temperature of the main steam,and the main steam temperature can't be automatically controlled during the process of varying load of units etc.,adjustment and optimization of the main steam temperature control,the inlet temperature control for separators,and the proportioning ratio control of water and coal etc.have been carried out.After optimization,the main operation parameters,such as the main steam temperature and pressure,and the load of units etc.,can be controlled in a reasonable range under dynamic and static operation conditions,enhancing the automatic control level of units.