基于燃烧均匀性的对冲燃烧锅炉高温腐蚀抑制

High temperature corrosion inhibition for opposed firing boiler based on combustion distribution evenness

为了消除锅炉水冷壁高温腐蚀对锅炉安全运行的影响,通过实测电厂锅炉空预器入口的O2和CO体积分数沿锅炉横向截面的分布特性,从燃烧均匀性角度分析侧墙还原性气氛的主要原因,并进行相应优化.结果表明:超超临界对冲燃烧锅炉由于炉膛中间燃烧状况剧烈,产生一定的负压,导致靠近侧墙的燃烧器的燃烧器区域过量空气系数比设计值低0.11.燃烧器由于供氧不足产生CO,是侧墙还原性气氛及水冷壁高温腐蚀的主要原因.将靠近侧墙的燃烧器一次风煤粉浓度降低20%后,该燃烧器区域的过量空气系数达到设计值,侧墙附近O2的体积分数升高约2%,水冷壁的高温腐蚀程度减弱84.7%,锅炉的热效率未受影响.

The distribution characteristics of oxygen volume fraction and carbon monoxide volume fraction were measured at the inlet of air pre-heater along the transverse section of boiler to eliminate the effect of high temperature corrosion of boiler water wall on the boiler＇s safe operation.The main reason of reducing atmosphere beside side wall was analyzed from the perspective of combustion distribution evenness.Accordingly,the reducing atmosphere beside side wall was further optimized.The detected excess air ratio was 0.11 lower than the designed value in the burner region adjacent to the side wall,which was due to the negative pressure caused by the violent combustion in the center of the furnace of ultra-supercritical opposed firing boiler.The deficit of oxygen led to the formation of CO,which was found to be the main reason for reducing atmosphere beside side wall and high temperature corrosion of boiler water wall.The optimization was conducted by decreasing the pulverized coal concentration of primary air by 20%in the burner region close to the side wall.In consequence,the excess air ratio in this burner region reached the designed value.The oxygen volume fraction increased by 2%,and the high temperature corrosion degree of boiler water wall declined by 84.7%.Meanwhile,the thermal efficiency of the boiler was not affected.