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。

After the ultra-low emission transformation of domestic coal-fired unit boilers, there are varying degrees of high-temperature sulfur corrosion problems in the boiler water wall, especially the opposed combustion boiler, which seriously threaten the safe and stable operation of the boiler.In order to fundamentally solve the problem of high temperature sulfur corrosion of water wall, an air membrane protection technology was proposed to prevent high temperature sulfur corrosion of opposed combustion boiler water wall. The numerical calculation software was used to simulate and calculate the flue gas composition near the water wall during boiler operation. Taking the volume fraction of O2, CO and H2S components in the flue gas as the main research object, the position, number of layers, vertical inclination and air volume ratio of the air membrane protection nozzle were optimized, and the research results were compared and verified through the on-site verification test.The numerical calculation research and field test results show that after the application of air membrane protection technology, the changes of boiler thermal efficiency and NOx volume concentration at the inlet of SCR denitration reactor are insignificant, and the boiler operation parameters are normal, which will not have an adverse impact on the normal operation of the boiler.After the application of air membrane protection technology, the average volume fraction of O2 near the water wall can reach more than 5.0%, which is more than 5 times higher than that before application, and the average volume fraction of H2S can be reduced by more than 85% compared with that before application, which can be controlled below 100 μL/L.The reducing atmosphere in the area near the water wall is eliminated and the concentration of corrosive gas H2S is significantly reduced.The high-temperature sulfur corrosion ofwater wall can be fundamentally treated and the safety of boiler operation is significantly improved.The air membrane protection technology of water wall has a good demonstration effect on the prevention and treatment of high temperature sulfur corrosion of boiler water wall of the same type of unit.

0 引言

1 水冷壁高温腐蚀机理

2 锅炉概况与燃煤特性

3 数值模拟分析

   3.1 数学模型

   3.2 数值模拟工况

4 数值模拟结果与分析

   4.1 数值模拟可靠性验证

   4.2 喷口参数对近壁烟气成分的影响

   4.3 优化工况与原始工况对比

5 气膜保护系统优化结果

   5.1 气膜保护喷口布置方案

   5.2 气膜保护系统布置方案

6 工业示范应用分析

   6.1 水冷壁近壁烟气成分分析

   6.2 锅炉运行参数影响分析

7 结论