过量空气系数对燃煤锅炉SNCR脱硝的影响

Impact of Excess Air Coefficient on SNCR Denitrification in Coal-Fired Boiler

为探究NO_(x)超低排放规律,数值模拟研究了总过量空气系数、主燃区过量空气系数对某330 MW燃煤锅炉NO_(x)排放的影响。结果表明,炉膛内速度流场和温度场具有协同性,且协同程度越高,温度上升越快,其NO_(x)生成也越多;NO_(x)沿着环状温度场集中生成,并富集在炉膛四周。主燃区喷尿素可有效降低炉膛内整体NO_(x)浓度。对比喷尿素前后发现:NO_(x)浓度随总过量空气系数减小而变小;主燃区过量空气系数越小,NO_(x)浓度也越小,最佳主燃区过量空气系数为0.92。

To obtain ultra-low NO_(x) emission,the effects of total excess air coefficient,air coefficient in main combustion zone on a 330 MW coal-fired boiler combustion were numerically studied.The results show that the velocity field and temperature field in the furnace have synergy,and the better the synergy is,the faster the temperature rises,and the more NO_(x) is generated.NO_(x) can intensively generate along the ring-shaped temperature field,and enrich near the four-sided furnace.Spraying urea in the main combustion zone can effectively reduce the overall NO_(x) concentration in the furnace.Comparison is made between before and after urea spraying.With the decrease of the total excess air coefficient,the NO_(x) concentration decreased.The smaller the air coefficient in the main combustion zone is,the smaller the NO_(x) concentration is,and the optimum air coefficient in the main combustion zone is 0.92.