柴油机氨基SCR化学反应特性的试验研究

Experimental Research on NH_3-SCR Chemical Reaction Characteristics of Diesel Engine

为了研究不同因素对氨基SCR化学反应特性的影响,基于某重型柴油机及其已有SCR装置,分别针对不同空速、温度和氨氮比对氨基SCR化学反应特性中NO_x转化效率和SCR反应速率的影响以及升温过程对NH3的饱和存储量的影响开展试验研究。结果表明:NO_x平均转化速率基本上由温度决定,而NO_x转化效率则由温度和空速共同影响;随着氨氮比增加,NO_x转化效率也会随之升高,但是当氨氮比大于1.0后,NO_x转化效率的变化开始趋于平缓,且氨氮比越大NH_3泄漏会越早超过10×10^(-6)(法规规定);而且温度升高引起的NH3饱和存储量的变化会造成NH3泄漏。试验还获得不同空速、不同温度下的NO_x最大转化效率MAP图和NH3饱和存储量的动态方程,对于SCR控制策略的建立具有重要意义。

In order to study the effects of different factors on NH3‐SCR chemical reaction characteristics ,the influences of dif‐ferent space velocities ,temperatures and ammonia nitrogen ratios on NO x conversion efficiency and SCR reaction rate and the influence of temperature increasing on NH3 saturated storage were studied based on a heavy duty diesel engine and its existing SCR device .The results show that the average NO x conversion rate depends on temperature and NO x conversion efficiency is affected by both temperature and space velocity .Besides ,NO x conversion efficiency increases with the increase of ammonia ni‐trogen ratio ,but tends to be a constant value when the ammonia nitrogen ratio is beyond 1 .0 and the greater ammonia nitrogen ratio will leads to the earlier exceeding of NH3 leakage limit of 10 × 10 - 6 .The change of NH3 saturation storage led by the tem‐perature increasing will lead to NH3 leakage .Furthermore ,the biggest NO x conversion efficiency MAP under different space velocities and temperatures as well as the dynamic equation of NH3 saturated storage were acquired by the test ,which is of great importance to the SCR control strategy building .