燃尽风率对四角切圆锅炉燃烧及NOx生成特性的影响

对某电厂一台300 MW四角切圆锅炉低氮改造后的NOx生成特性进行了数值模拟计算,分析了燃尽风率对NOx生成特性的影响。分析结果表明:燃尽风率增大时,在主燃烧区喷入空气量减少,导致煤粉燃烧不完全、温度降低;燃尽区的富氧氛围使未燃尽的煤粉进一步完全燃烧;主燃烧区的还原性氛围使得该区域NOx会随着燃尽风率的增大而减少;燃尽区的高温以及较低的CO浓度降低了该区域的还原性氛围,使NOx排放量增加。综合考虑NOx排放和消旋效果,该炉型锅炉采用30%的燃尽风率是比较合理的。

Effect of Burnout Air Rate on Combustion and Pollutant NOx Formation Generation Characteristics of Tangentially Fired Boiler

The formation characteristics of NOx of a 300 MW tangentially-circular boiler with low NOx combustion system were numerically calculated.The results showed that when the rise of exhaust air rate decreased the amount of air injected into the main combustion area which leading to incomplete combustion of coal powder and lower temperature. However,the combustion of unburned coal in the burnt out region improve the temperature and oxygen-rich atmosphere in this region. The formation of NOx decrease with the increasing of exhaust air rate due to the reducing atmosphere in main combustion region. However,high temperature and low CO concentration decreased reducing atmosphere in the burnt out region and increase NOx emissions to some extent. Comprehensively considering of NOx emissions and racemization effects,it is reasonable to use a 30% burnout air rate for this boiler.