600 MW切圆锅炉LNCFS系统低NO_x燃烧特性数值研究

Numerical Investigation on the Characteristic of Low NO_x Combustion in a 600MW Tangential Boiler

通过数值模拟研究了不同燃尽风配风方式对600 MW四角切圆锅炉炉内流动、燃烧以及NO_x生成的影响。结果表明,采用LNCFS深度空气分级低NO_x燃烧系统,NO_x排放量可控制在400 mg/m^3(6%O_2)以下,较好地抑制了燃烧过程中NO_x的生成。深度空气分级燃烧方式主要通过抑制主燃区内挥发分NO_x的生成来控制最终的NO_x排放,但对焦炭燃尽后期NO_x生成影响较小。伴随剩余煤粉的燃尽,NO_x生成量又有所反弹,影响了炉膛出口最终的NO_x排放量。

The influx, combustion and NOx emission were studied on the different distribu- tion of over fire air by numerical simulation. Numerical results show that the NOr emission can be controlled below 400 mg/m3 （6 % O2 ）, the combustion system of LNCFS can inhibit the NOx emission better. Deep air staging can control the final NOx emission by inhibiting the volatile NOx in the primary combustion zone, but the char NO. was controlled by the deep air staging worse. With the burn out of remaining pulverized coal, the increasing of NOx emis- sion is the main reason on influencing the final NOx emission.