尿素结晶形成机理及其对柴油机后处理器的影响分析

Analysis of Mechanism of Urea Crystallization Formation and Its Influence on Diesel Engine Afterprocessor

本文应用11L国六柴油机以及高效SCR路线开展台架试验,以国六低硫柴油作为实验用油,设计一定的工况开展尿素结晶试验。在试验运行至不同时间点后,分别使用内窥镜对后处理器混合器进行探视,相应的时间点为运行至20h时、运行至40h时、运行至60h时。通过试验观察并分析尿素结晶对排气背压、下游NOx排放情况的影响情况及其原因,并通过实验分析尿素结晶识别策略。结果显示,尿素结晶的分布区域主要在后处理器混合器旋流板上,尿素结晶出现后,下游NOx排放情况总体表现出不断劣化的变化趋势,相应的最高背压也呈现出明显的上升情况,且对应的氨混均匀性系数会出现明显的下降。

This article applies the 11L Guoliu diesel engine and efficient SCR route to conduct bench tests,using Guoliu low sulfur diesel as the experimental oil,and designing certain operating conditions to carry out urea crystallization tests.After the experiment runs to different time points,use an endoscope to explore the post processor mixer,and the corresponding time points are running to 20 hours,running to 40 hours,and running to 60 hours.Observe and analyze the impact and reasons of urea crystallization on exhaust backpressure and downstream NOx emissions through experiments,and analyze the identification strategy of urea crystallization through experiments.The results show that the distribution area of urea crystallization is mainly on the vortex plate of the post processor mixer.After the appearance of urea crystallization,the downstream NOx emission overall shows a continuous deterioration trend,and the corresponding maximum back pressure also shows a significant increase,and the corresponding ammonia mixing uniformity coefficient will show a significant decrease.