某600 MW四角切圆锅炉低氮燃烧改造后一直存在炉内高温腐蚀和两侧再热汽温偏差大的问题，对炉内贴壁气氛进行试验测试并进行数值模拟计算。结果表明：炉内局部还原性气氛尤为浓烈，特别是4号角区域，局部CO体积分数达到了12%；SOFA风量降低至总风量的20%后，炉内CO和H2S体积分数明显减小，出口NOx体积分数上升幅度在20%以内；4号角二次风量低亦是再热汽温偏差较大的主要原因。在锅炉实际运行中降低燃尽风率、加大4号角二次风量，两侧汽温偏差均小于3 ℃，贴壁区域局部过强还原性气氛亦得到改善。

After low NOx burner modification,the problems of severe high temperature corrosion and reheat steam temperature deviation appear in a 600 MW tangentially coal-fired boiler.The corresponding investigation is carried out by experimentally probing the near wall atmosphere and numerical simulation.The results indicate that the reducing atmosphere of local furnace is particularly strong.The local concentration of CO is 12% near the horn 4.The concentration of CO and H2 S in furnace decreases significantly and the concentration of NOx at outlet of furnace rises less than 20% after air flow of SOFA decreases to 20% of total air rate.The primary cause of temperature deviation of reheating steam is the low secondary air flow of the horn 4.In actual running of boiler,the temperature deviation of reheating steam is less than 3 ℃and strong reducing atmosphere of local near water wall is improved after the rate of over-fired air is decreased and the secondary air flow is increased for the horn 4.

TK223