非均匀入口条件下SCR脱硝系统精准喷氨策略

Precise ammonia injection strategy in SCR denitrification system based on non-uniform inlet parameters

采用数值计算的方法,根据全尺度数值模拟计算结果和实际测量数据获得符合工程实际情况的SCR非均匀入口边界条件,模拟了整个SCR系统的烟气流动过程.根据喷氨格栅处速度场和浓度场获取NO通量,以此为基准精确分配各喷管喷氨量.研究了不同喷口布置的氨气与NO的对流扩散混合特性,分析了喷氨格栅中喷口密度N、开孔率φ、喷口角度α三个结构参数对SCR反应器内氨氮混合质量、氨氮比分布均匀性的影响.结果表明:增大喷口密度N可以有效地优化氨氮混合效果.当N>15.34个/m^2时,增加N对氨氮混合效果的影响不再显著;混合指数β随着喷口开孔率φ的增大会出现先减小后增大的趋势;改变喷口角度α可以改善氨氮混合效果,喷口垂直布置时氨氮混合效果最佳.

Based on full scale numerical simulation results and measured data,numerical simulation was carried out to obtain the realistic non-uniform inlet parameters as the initial condition,the process of flue gas flowin the whole SCR system was simulated. According to the velocity field and concentration field at the ammonia injection grid,NO flux was obtained and the amount of ammonia in every spout was precisely determined by NO flux. The convective diffusion mixing efficiency of NH3 and NO with different arrangements of spouts was also simulated to analyze the effects of spout density N,opening rate φ and spout angle α on the mixing efficiency and ammonia-nitrogen ratio uniformity in SCR reactor. Results showthat increasing N can effectively improve the mixing effect,however,when N 15. 34/m^2,this improvement will not be obvious; The mixing index β firstly decreases and then increases with the increase of φ; The mixing effect is elevated when α changes from 0° to 90°,and the vertical arrangement works best.