基于空气分级燃烧与SCR脱硝的燃煤锅炉NO_(x)排放控制

NO_(x)Emission Control of Coal-Fired Boilers Based on Fractional Air Combustion and SCR Denitrification

350 MW燃煤发电机组四角切圆锅炉在实际运行过程中,存在炉内NO_(x)生成量大、选择性催化还原法(SCR)脱销反应器入口NO_(x)浓度高、影响脱硝效率等问题。根据空气分级燃烧原理,在煤炭燃烧过程中控制空气的供给量,减少锅炉内NO_(x)生成量,在此基础上运用SCR脱硝技术,进一步控制燃煤烟气中NO_(x)的排放浓度。通过分析煤炭燃烧过程中NO_(x)的生成特性,对燃煤锅炉进行了实验研究。实验结果表明,在常用煤种与不同锅炉负荷条件下,尤其在低负荷时,采用联合控制方法的脱硝效率达到85%,有效降低了NO_(x)排放浓度。

In the actual operation of the 350 MW coal-fired four-corner tangential boiler,there are some problems such as large NO_(x)generation in the furnace and high concentration at the inlet of the SCR reactor affecting the denitration efficiency.According to the principle of air classification combustion,the supply of air is controlled during the coal combustion process to reduce the amount of NO_(x)generated in the furnace.On this basis,SCR denitrification technology is used to further control the emission concentration of NO_(x)in the coal flue gas.By analyzing the characteristics of NO_(x)generation in coal combustion,the coal boiler is tested.Test results show that under the conditions of common coal and different boiler loads,especially at low loads,the denitrification efficiency reaches 85%by using the joint control method,which effectively reduces the emission concentration of NO_(x).