SCR 催化器内浓度场影响因素的仿真研究

为提高 NO x 的转化效率，研究了温度、空速、氨氮比和 NO 与 NO2的摩尔比对 SCR 催化器内浓度场的影响。试验验证了 SCR 化学反应模型，将准确的化学反应动力学参数输入到 Fire 软件并建立 SCR 催化器模型，计算分析 SCR催化器内组分浓度场的影响因素。得出以下结论：温度越高，NH3和 HCNO 的浓度越高；流体涡流为喷雾液滴蒸发和热解提供了有利条件；空速太大，NO 的转化效率会降低；当氨氮比为1时，理论上 NO x 的转化效率达到最高；当氨氮比小于1时，NO x 转化效率随氨氮比的升高而升高，但在接近1时候产生氨滑移；当氨氮比大于1时，NO x 转化效率变化不大但会产生大量氨滑移。因此最佳的氨氮比应是在保证较小的氨滑移的前提下尽可能提高 NO x 转化效率。

Simulation of Influencing Factors of Component Concentration Field inside SCR Catalytic Converter

In order to improve the NO x conversion efficiency ,the effects of temperature ,gas hourly space velocity (GHSV) , NH3 /NO x ratio and n(NO) ∶ n(NO2 )molar ratio on the concentration field inside SCR catalytic converter were studied .The test verified the feasibility of SCR chemical reaction model .Accurate kinetic parameters of chemical reaction were inputted to the FIRE software and the simulation model of SCR catalytic converter was established ,and then the concentration field influ‐encing factors inside the SCR catalytic converter were simulated and analyzed .The results show that the higher temperature will lead to the larger concentration of NH3 and HCNO .The swirl flow brings the advantageous conditions for the evaporation and thermal decomposition of spray droplet .The higher GHSV will influence the NO conversion efficiency .The conversion effi‐ciency of NO x reaches the theoretical largest value when the NH3 /NO x ratio is 1 ,increases with the increase of NH3 /NO x ra‐tio when the ratio is less than 1 and is little influenced when the ratio is beyond 1 .The ammonia slip happens as the NH3 /NO x ratio is near to 1 and the much ammonia slips when the ratio is larger than 1 .Accordingly ,the optimal NH3 /NO x ratio should guarantee the largest conversion efficiency of NO x under the premise of least ammonia slip .