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逆流式混合器的设计及尿素结晶风险评估方法研究

韩峰1，张晓丽1，王意宝1，胡晓艳1，王霞1，石代龙2   

  1. 1. 潍柴动力股份有限公司发动机研究院，潍坊 261205；2.山东大学，济南 250061
  • 出版日期:2019-03-12 发布日期:2019-03-12
  • 基金资助:
     

Contra-flow urea mixer optimization and study on deposit mechanism

    

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  • Online:2019-03-12 Published:2019-03-12
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摘要： 传统双层管SCR混合器在排气温度低的工况易在混合器壁面形成尿素结晶。为解决此问题，设计了一种新型逆流式SCR混合器及其与喷嘴座的集成布置方案。利用CFD技术和台架试验相结合验证了逆流式混合器的预防尿素结晶能力和对NOx排放的影响，并对尿素结晶机理及尿素结晶风险评估方法进行了深入研究，提出了基于“尿素结晶能量因子”比较不同工况尿素结晶风险的方法。对逆流式SCR催化器进行台架瞬态排放测试试验以及30h发动机台架尿素结晶验证试验，台架试验结果表明：逆流式结构混合器的瞬态NOx转化率提高了1.8%，30h台架尿素结晶试验表明逆流式混合器壁面未出现尿素结晶。

关键词: 逆流式混合器, 尿素结晶, 能量因子法, CFD技术

Abstract: Urea depositexisted in the traditional double-tube SCR catalysts atlow exhaust temperaturecondition. In order to solve this problem, a new type contra-flow SCR mixer and a layout?scheme of the nozzles integrated with mixer have been proposed in this work. By combining CFD technology and bench test, deposit formation performance and emission performance of the contra-flow mixer were verified. The mechanism and risk assessment of urea deposit formation were deep studied, deposit formation Excess Energy Ratio (EER) was proposed to compare deposit formation risk in different operating conditions. The emission test in transient state and 30 hours engine bench test to verify deposit formation were conducted. The bench test results showed that the conversion efficiency of nitrogen oxides of the contra-flow mixer increased by 1.8%. The 30 hours bench test results showed that no deposits were formed on walls of the contra-flow mixer.

Key words: Contra-flow mixer, Urea Deposit, Excess Energy Ratio, CFD

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