农用发动机SCR系统内尿素分解特性研究

doi:10.13733/j.jcam.issn.2095-5553.2023.09.019

摘要/Abstract

摘要： 以某型号非道路发动机为试验发动机，反应段为直径7寸、目数200、长度25mm和50mm规格的钒基挤出式催化剂各两段组合而成的SCR催化反应器，研究催化剂内部氨的生成特性，探究结构参数与工况条件对催化剂内部尿素分解率和氨分布的影响。结果表明：随着排气温度的升高和流量的减小，使得催化剂径向测量截面氨分布均匀性提高，SCR反应效率提高。在各试验工况和结构条件下，尿素分解主要发生在催化剂的前100mm，在此长度内分解速率较快，后逐渐变慢。在催化剂长度为150mm时，各个工况下催化剂出口处尿素平均分解率均大于80%，可满足标准SCR反应所需。通过台架试验对尿素分解特性及氨分布的研究，为提高车用尿素利用效率和优化后处理系统催化剂设计提供一定的参考。

关键词: 农用发动机, 催化剂, 氨分布, 尿素分解, 分解率, 车辆与动力

Abstract: Taking a model of offroad engine as the test engine, and the reaction section was a SCR catalyst with two sections of vanadiumbased extruded catalysts of 7″ diameter, 200 mesh, 25mm and 50mm in length. The ammonia generation characteristics inside the catalyst were investigated, and explored the effects of structural parameters and operating conditions on the urea decomposition rate and ammonia distribution inside the catalyst. The results showed that with the increase of exhaust gas temperature and the decrease of flow rate, the uniformity of ammonia distribution in the radial measurement crosssection of the catalyst and the efficiency of SCR reaction was increased.Under each test condition and structural condition, urea decomposition mainly occurred in the first 100mm of the catalyst, and the decomposition rate was faster in this length and gradually slowed down. At 150mm catalyst length, the average decomposition rate of urea at the catalyst outlet was more than 80% under all conditions, which could meet the requirements of standard SCR reaction. In this paper, the study of urea decomposition characteristics and ammonia distribution through bench test can provide some reference for improving the efficiency of urea utilization and optimizing the catalyst design of aftertreatment system.

Key words: agricultural engines, catalyst, ammonia distribution, urea decomposition, decomposition rate, vehicle and power

中图分类号:

S218.5： TK421+.5

杨朔, 杜慧勇, 李可, 王站成, 李民, 范晨阳. 农用发动机SCR系统内尿素分解特性研究[J]. 中国农机化学报, 2023, 44(9): 131-136.

Yang Shuo, Du Huiyong, Li Ke, Wang Zhancheng, Li Min, Fan Chenyang. Research of urea decomposition characteristics in agricultural engine SCR system[J]. Journal of Chinese Agricultural Mechanization, 2023, 44(9): 131-136.

参考文献

［1］　郑祥, 牛志刚, 刘伟伟, 等. 进气道喷水对柴油机节能及NOX排放影响的试验研究［J］. 中国农机化学报, 2013, 34(2): 169-172, 193.
Zheng Xiang, Niu Zhigang, Liu Weiwei, et al. Experimental research of the inletwater injection on diesel engine energysaving and NOX emissions ［J］. Journal of Chinese Agricultural Mechanization, 2013, 34(2): 169-172, 193.
［2］　Capetillo A J, Fernando I, Dominik S, et al. Multiphase modelling of SCR systems: Using the taguchi method for mixer optimization ［J］. SAE International Journal of Engines, 2017, 10(1): 61-71.
［3］　刘强, 柴洋, 胡晓艳, 等. 柴油机SCR系统混合器优化设计与仿真分析［J］. 车用发动机, 2022(1): 71-77.
Liu Qiang, Chai Yang, Hu Xiaoyan, et al. Optimization and simulation for SCR mixer of diesel engine ［J］. Vehicle Engine, 2022(1): 71-77.
［4］　Brack W, Heine B, Birkhold F, et al. Formation of ureabased deposits in an exhaust system: Numerical predictions and experimental observations on a hot gas test bench ［J］. Emission Control Science and Technology, 2016, 2(3): 115-23.
［5］　Nova I, Tronconi E. UreaSCR technology for deNOX after treatment of diesel exhausts ［M］. Springer New York, 2014.
［6］　Liu S, Wang B, Guo Z, et al. Experimental investigation of urea injection strategy for closecoupled SCR after treatment system to meet ultralow NOX emission regulation ［J］. Applied Thermal Engineering, 2022, 205: 117994.
［7］　Huang H, Chen Y, Li Z, et al. Analysis of deposit formation mechanism and structure optimization in ureaSCR system of diesel engine ［J］. Fuel, 2020, 265: 116941.
［8］　冯鹏飞. 柴油机SCR系统尿素喷雾蒸发分解混合与结晶研究［D］. 长沙: 湖南大学, 2018.
Feng Pengfei. Studies on the evaporation, decomposition mixing and crystallization of the urea spray in diesel SCR systems ［D］. Changsha: Hunan University, 2018.
［9］　干旭波, 姚栋伟, 吴锋, 等. 柴油机SCR系统尿素分解试验研究［C］. 内燃机科技(高校篇)——中国内燃机学会第六届青年学术年会论文集, 2015: 58-61.
［10］　马军彦, 李君, 曲大为, 等. 柴油机SCR系统尿素分解效率研究［J］. 农业机械学报, 2015, 46(6): 282-286, 309.
Ma Junyan, Li Jun, Qu Dawei, et al. Urea decomposition efficiency of diesel engine SCR system ［J］. Transactions of the Chinese Society for Agricultural Machinery, 2015, 46(6): 282-286, 309.
［11］　唐韬, 赵彦光, 华伦, 等. 柴油机SCR系统尿素水溶液喷雾分解的试验研究［J］. 内燃机工程, 2015, 36(1): 1-5.Tang Tao, Zhao Yanguang, Hua Lun, et al. Experimental study of urea solution spray and decomposition of SCR system for diesel engine ［J］. Chinese Internal Combustion Engine Engineering, 2015, 36(1): 1-5.
［12］　王军, 王兴华, 季亮, 等. SCR系统尿素水溶液喷雾分解影响因素数值模拟［J］. 农业机械学报, 2016, 47(10): 372-375, 371.
Wang Jun, Wang Xinghua, Ji Liang, et al. Numerical simulation of influence factors on urea solution spray and decomposition of SCR system ［J］. Transactions of the Chinese Society for Agricultural Machinery, 2016, 47(10): 372-375, 371.
［13］　Krum K, Patil R, Christensen H, et al. Kinetic modeling of urea decomposition and byproduct formation ［J］. Chemical Engineering Science, 2021, 230: 116-138.
［14］　Wu Y, Wang F, Tang W, et al. Urea decomposition and implication for NOX reduction with CuZeolite and VanadiaSelective catalytic reduction ［J］. Chemical Engineering & Technology, 2020, 43(9): 1758-1764.
［15］　谭丕强, 段立爽, 楼狄明, 等. 柴油机选择性催化还原捕集技术(SDPF)的研究现状与发展趋势［J］. 中国环境科学, 2021, 41(12): 5495-5511.
Tan Piqiang, Duan Lishuang, Lou Diming, et al. Research status and development trend of selective catalytic reduction filter (SDPF) technology of diesel engines ［J］. China Environmental Science, 2021, 41(12): 5495-5511.

[1]	赵敏, 杨波, 李伟. 液压冲击抑制方法研究现状与展望[J]. 中国农机化学报, 2023, 44(9): 123-130.
[2]	向浩, 高巧明, 韦增健, 许鹏, 曾俊豪, 赵鹏飞. 山地模块化电动底盘的同侧输出行星减速器设计[J]. 中国农机化学报, 2023, 44(8): 133-140.
[3]	范梦元, 杜慧勇, 李民, 谢俊杰, 王站成, 苗家轩. 配气机构对柴油机前端噪声贡献度评价方法的试验研究[J]. 中国农机化学报, 2023, 44(8): 141-147.