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催化剂的非均匀分布对船舶SCR系统特性的影响

梁海明 许红祥 雷小霞 陈正科 潘光明

梁海明,许红祥,雷小霞,等.催化剂的非均匀分布对船舶SCR系统特性的影响[J].环境工程技术学报,2024,14(3):836-845 doi: 10.12153/j.issn.1674-991X.20230713
引用本文: 梁海明,许红祥,雷小霞,等.催化剂的非均匀分布对船舶SCR系统特性的影响[J].环境工程技术学报,2024,14(3):836-845 doi: 10.12153/j.issn.1674-991X.20230713
LIANG H M,XU H X,LEI X X,et al.Influence of non-uniform distribution of catalysts on the characteristics of ship SCR system[J].Journal of Environmental Engineering Technology,2024,14(3):836-845 doi: 10.12153/j.issn.1674-991X.20230713
Citation: LIANG H M,XU H X,LEI X X,et al.Influence of non-uniform distribution of catalysts on the characteristics of ship SCR system[J].Journal of Environmental Engineering Technology,2024,14(3):836-845 doi: 10.12153/j.issn.1674-991X.20230713

催化剂的非均匀分布对船舶SCR系统特性的影响

doi: 10.12153/j.issn.1674-991X.20230713
基金项目: 广西壮族自治区交通运输厅2020年度第三批广西交通运输行业重点科技项目(JZY2020KZD04)
详细信息
    作者简介:

    梁海明(1987—)男,副教授,研究方向为柴油机尾气后处理技术,627525318@qq.com

    通讯作者:

    许红祥(1995—)男,硕士,研究方向为汽车空气动力学、新能源与节能减排技术,1419809016@qq.com

  • 中图分类号: X736.3

Influence of non-uniform distribution of catalysts on the characteristics of ship SCR system

  • 摘要:

    选择性催化还原(SCR)系统常用于降低柴油发动机尾气排放出的氮氧化物(NOx)。为进一步提高其脱硝性能,首先建立三维数值模拟模型,通过改变SCR转换器中孔隙率来实现催化剂的非均匀分布,从而研究在不同发动机负荷下的催化剂非均匀分布对SCR系统中的流动、传质和传热等性能的影响;其次,与催化剂的均匀分布进行对比,重点考察催化剂非均匀分布时对SCR系统性能的影响;最后,基于场协同原理分析SCR系统中的速度场和温度场对传热过程的影响。结果表明:催化剂的非均匀分布可以提高SCR系统的性能。在发动机25%的负荷下,与均匀分布相比,案例P-R5的压力损失降低165 Pa,脱硝率提高了0.8%,氨的逸出量减少了7 mg/L;案例P-R5的温度梯度高于均匀孔隙率催化剂温度梯度的最大峰值,这表明向外部传递的能量较少,催化剂非均匀分布的结构可以保持催化区域的温度,提高催化剂的活性,有利于脱硝反应。

     

  • 图  1  SCR系统示意

    Figure  1.  Schematic diagram of SCR system

    图  2  不同发动机负荷下的仿真模拟结果与试验值的比较

    Figure  2.  Comparison of simulation results and experimental values under different engine loads

    图  3  不同发动机负荷下案例的压力损失

    Figure  3.  Pressure drop of cases under different engine loads

    图  4  不同案例在50%发动机负荷下的压力分布云图

    Figure  4.  Pressure distribution cloud map of different cases at 50% engine load

    图  5  50%发动机负荷条件下SCR系统中心线温度分布

    Figure  5.  SCR system centerline temperature distribution at 50% engine load

    图  6  发动机负荷为50%时案例的温度分布

    Figure  6.  Temperature distribution of the cases at 50% engine load

    图  7  不同发动机负荷下案例的脱硝率

    Figure  7.  NOx conversion efficiency of the cases under different engine loads

    图  8  50%和100%发动机负荷下案例的中心平面NO含量的分布

    Figure  8.  Distribution of NO mass fraction in the central plane of the cases at 50% and 100% engine loads

    图  9  不同发动机负荷下SCR系统出口氨的逸出量

    Figure  9.  Ammonia escape at the SCR system outlet under different engine loads

    图  10  不同案例在50%和100%发动机负荷下氨的逸出量分布

    Figure  10.  Ammonia escape in different cases under 50% and 100% engine loads

    图  11  不同发动机负荷下案例的轴向温度梯度峰值的变化

    Figure  11.  Variation in peak axial temperature gradient under different engine loads

    图  12  不同发动机负荷下催化转化器前部的平均速度和均匀性系数

    Figure  12.  Average speed and uniformity coefficient in front of catalytic converter under different engine loads

    表  1  SCR系统物理模型参数

    Table  1.   SCR system physical model parameters

    入口和出口
    截面直径
    d2)/mm
    入口或出口
    段长度
    L1)/mm
    膨胀角度
    α)/(°)
    催化反应
    段直径
    d1)/mm
    催化反应
    段长度
    L2)/mm
    120 60 90 240 320
    下载: 导出CSV

    表  2  不同负荷下船用柴油机的催化转化器的边界条件

    Table  2.   Boundary conditions for catalytic converters of marine diesel engines under different loads

    柴油机负荷/%质量流量/(kg/s)尾气压力/MPa尾气温度/℃NOx含量/(mg/L)H2O含量/%O2含量/%CO2含量/%理论氨氮比
    250.560.162551 2183.1316.163.600.821
    501.080.2283201 1313.1215.064.380.797
    751.520.3183501 0543.1114.564.750.731
    1001.840.3924001 1243.1113.695.370.693
    下载: 导出CSV

    表  3  案例设置

    Table  3.   Cases setting

    案例 催化剂的分布 区域半径/mm 孔隙率
    区域1(R1 区域2(R2 区域1(ε1 区域2(ε2
    P-R1 催化剂非均匀
    分布
    40 80 0.41 0.75
    P-R2 20 80 0.41 0.75
    P-R3 40 100 0.41 0.75
    P-R4 40 80 0.75 0.75
    P-R5 40 80 0.41 0.41
    P0 催化剂均匀分布 整个区域的孔隙率为0.65,半径为120 mm
    下载: 导出CSV

    表  4  网格独立性

    Table  4.   Research on grid independence

    网格类型网格数量/个出口处NO浓度/(mg/L)
    粗网格59 904227
    中网格449 280203
    细网格3 669 850200
    下载: 导出CSV
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出版历程
  • 收稿日期:  2023-11-27
  • 录用日期:  2024-03-06
  • 修回日期:  2024-02-02

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