面向NO_x脱除率优化的烟气脱硝CFD仿真研究

CFD Simulation of Flue Gas DeNOx Process to Improve NO_x Removal Efficiency

烟气脱硝的技术关键是还原剂与烟气混合要尽可能均匀,混合气体通过催化剂层时速度分布要尽可能均匀。以600 MW超临界燃煤火力电站烟气脱硝(DeNOx)系统为对象,对还原剂氨和烟气的混合过程进行了计算流体力学仿真,研究了关键导流板对喷氨格栅前烟气速度分布和催化剂入口处烟气速度分布的影响,并确定其尺寸及安装位置。为提高催化剂入口氨浓度分布的均匀性,根据喷氨格栅处烟道截面速度分布特点,通过仿真寻优,得到了非均匀喷氨流量设定值。

The problem of dentrification efficiency of the SCR-DeNOx plant depending on the velocity and ammonia concentration distributions at the entrance of the catalyst layer is discussed. Taking the flue gas DeNOx of a 600 MW super-critical coal-fired power plant as an example, the flue gas/ammonia mixing is investigated with the CFD simulation software. The gate leaf to manipulate the velocity distribution of the mixed gas at the inlet of the catalyst layer is designed, and the load of the catalytic reactor becomes more uniformly designated. To achieve uniform distribution of the ammonia concentration in the mixed gas, the non-uniform ammonia injection is investigated and the set-points of the ammonia feeding rates at AIG-ammonia injection grids are determined. Simudation results show that both velocity and ammonia concentration distributions are under well control without significant increase of the pressure drop.