1025t/h四角切圆煤粉炉内空气过量系数对NO生成的影响

Impact of Air Excess Coefficients on NO Generation in 1025t/h Tangentially-fired Boilers

文章采用计算流体力学软件Fluent数值模拟了1 025 t/h四角切圆煤粉炉内的湍流扩散燃烧,分析了空气过量系数对炉内烟气速度、烟气温度和氮氧化物组分的影响。结果表明:空气过量系数会对炉内流场的空气动力学特性和温度场分布均匀性产生显著影响。煤粉炉膛最佳空气过量系数为1.07,此时炉内温度场、速度场和浓度场的分布可使燃烧中间产物HCN和NH_3较好的将燃料型NO还原为N_2,来充分发挥空气分级燃烧降低NO排放的功效。

In this paper, Fluent software was applied to simulate a turbulent diffusion flame in a 1025 t/h tangentially-fired boiler. Combustion characteristics were analyzed at various air excess coefficients, including gas velocity, gas temperature and nitrogen oxide composition. The results showed that the air excess coefficients significantly affected the air dynamic characteristics of the flow field and the distribution uniformity of the temperature field in the furnace. The optimum air excess coefficient was 1.07, at which there were fit temperature, velocity and concentration fields in the boiler which was helpful for the intermediate products HCN and NH3 to reduce NO into N2 during the generation of NO, indicating that the efficiency of NO emission reduction was achieved by means of air-staged combustion at air excess coefficients of 1.07.