对冲燃烧燃煤锅炉NOx深度减排技术应用分析

Application Research of Deep NOx Emission Reduction Technology for Wall Combustion Boiler

NOx超低排放已出现因氨逃逸造成空气预热器ABS严重堵塞现象,部分地区要求进一步控制NOx排放浓度由50 mg/m^3降低到30 mg/m^3,这必然会增加氨逃逸和加剧空气预热器堵塞。以某600MW对冲燃烧锅炉的NOx深度减排为对象,借助计算流体动力学(CFD)流场模拟提出了整体实施方案:更换现有喷氨格栅、优化现有导流板结构、新增三角翼型混合器、CEMS表计多点采样、喷氨控制策略优化。方案实施后,NOx排放浓度从50 mg/m^3降低至30 mg/m^3,高负荷下SCR反应器进、出口NOx分布CV均值分别为3.2%、19.1%,脱硝效率为95.5%时的氨逃逸浓度为2.0μL/L,局部氨逃逸最高浓度为2.5μL/L,达到了改造的预期目的。

The ultra-low emission of NOx has caused serious blockage of ABS in air preheater due to ammonia escape.Some areas require further control of NOx reduction from 50 mg/m^3 to 30 mg/m^3,which will inevitably increase ammonia escape and increase air preheater blockage.In this paper,the deep NOx emission reduction of a 600 MW opposed combustion boiler is taken as the object,and the overall implementation scheme is proposed with the aid of CFD flow field simulation:replacing the existing ammonia injection grid,optimizing the structure of the existing guide plate,adding a delta wing mixer,CEMS meter multi-point sampling,and optimizing the ammonia injection control strategy.After the implementation of the scheme,the NOx emission concentration was reduced from 50 mg/m^3 to 30 mg/m^3.The CV value of NOx distribution of high load at the inlet and outlet of SCR reactor was 3.2%and 19.1%When the denitrification efficiency was 95.5%,the ammonia escape concentration was 2.0μL/L,and the maximum local ammonia escape concentration was 2.5μL/L,achieving the expected purpose of reconstruction.