车用柴油机选择性催化还原技术研究进展

Progress of Research on Selective Catalytic Reduction Technology for Vehicle Diesel Engine

选择性催化还原技术(SCR)是目前唯一可以同时改善柴油机排放和燃油经济性的氮氧化物(NOX)净化技术,而以NH3作为还原剂的SCR技术(NH3-SCR)又是目前最成熟,最具推广前景的SCR技术。文章详细阐述了用于车用柴油机的NH3-SCR技术的反应机理,介绍了温度对SCR反应的影响;列举了典型SCR系统的主要部件并介绍了各部分的功能,以及法规中对车用尿素水溶液(AdBlue)主要指标的规定;总结了目前应用较多的开环、闭环两种控制策略的工作流程及特点,并且分析了各自的优缺点;在柴油机后处理系统集成的角度对SCR与颗粒捕集器(DPF)的两种整合方案进行了分析,对比了两种方案的优缺点;最后分析了SCR技术目前存在的几个问题。

Selective Catalyst Reduction Technology （SCR）isatpresenttheuniquetechnologywhichcanimprovetheemissionand reduce oil consumption simultaneously. And SCR technology using NH3 as reductant （NH3-SCR） is most maturely developed and has the brightest foreground. In this paper, the chemical reaction mechanism of Selective Catalytic Reduction technology was expatiated, and the effect of temperature on NOx conversion rate was analyzed： the function of main parts of SCR system was introduced, as well as the specifications ofAdBlue： a summarization of open loop and closed loop control strategies was made, and the advantages and disadvantages of each were analyzed; then the two different modes for the integration of SCR and DPF in diesel aftertreatment system were referred and contrasted; finally, the problems which block the popularization of SCR was put forward.