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The Chinese Journal of Process Engineering ›› 2022, Vol. 22 ›› Issue (8): 1040-1052.DOI: 10.12034/j.issn.1009-606X.221292

• Research Paper • Previous Articles     Next Articles

Numerical simulation of CO2 hydrogenation system in mixed catalyst bed at particle scale

Bo JIN1,  Yaxin ZHANG1,2*   

  1. 1. School of Chemical Engineering and Technology, Xinjiang University, Urumqi, Xinjiang 830046, China 2. State Key Laboratory of Chemistry and Utilization of Carbon Based Energy and Resources Xinjiang University, Urumqi, Xinjiang 830046, China
  • Received:2021-09-09 Revised:2021-11-25 Online:2022-08-28 Published:2022-08-28


靳波1, 张亚新1,2*   

  1. 1. 新疆大学化工学院,新疆 乌鲁木齐 830046 2. 新疆大学省部共建碳基能源资源化学与利用国家重点实验室, 新疆 乌鲁木齐 830046
  • 通讯作者: 张亚新 13619903328@163.com
  • 作者简介:靳波(1996-),男,河北省沧县人,硕士研究生,从事化工设备数值模拟与过程强化,E-mail: bobo19961223@163.com;通讯联系人,张亚新,E-mail: 13619903328@163.com.
  • 基金资助:

Abstract: The effective conversion of CO2 is important for achieving the goals of peak carbon dioxide emissions and carbon neutrality. Cylindrical particles have better thermal conductivity but smaller surface area when compared with heteromorphic particles, therefore, for better bed performance, the discrete element method (DEM) is used to perform particle-scale CFD simulations of a CO2 hydrogenation system in a mixed bed of heterogeneous particles, to investigate the effect of different stacking methods on the multi-physical field distribution, CO2 conversion and CH4 yield in the bed. The results show as follows: there is a diffusion resistance within the catalyst, as the reaction progress, the material within the particles changes from stratified distribution to uniform distribution. Compared to conventional beds, random mixed beds are less prone to hot spot fluctuations before steady state and has higher yields at steady state, while columnar bed have a more uniform radial heat field and higher hot spot. Of the four regular mixed beds, the two catalyst beds with 4 holes at bottom have more uniform overall flow fields, fewer high velocity zones, larger pressure drops, a larger proportion of high temperature zones and less fluctuation of hot spot before steady state than the two catalyst beds with columnar bottom. 2-layer mixed stacking-bottom 4 holes catalyst bed has maximum steady-state exit CO2 conversion and CH4 yield. The 4-layer mixed stacking-bottom 4 holes catalyst bed has high percentage of the high temperature region, which tends to increase as the reaction progress, resulting in significant decrease in CO2 conversion and CH4 yield.

Key words: packed bed, particle mixed, CO2 hydrogenation, methanation, numerical simulation, discrete element method, particle scale

摘要: CO2的有效转化对于实现“双碳”目标具有重要意义。柱形颗粒比异形颗粒具有更优良的热导性和更小的颗粒表面积,因此,为获得更优异的床层性能,采用离散元方法(DEM)对异形颗粒混合堆积床内的CO2加氢反应体系进行颗粒尺度CFD模拟计算,探究不同堆积方式对床层多物理场分布、CO2转化率及CH4产率的影响。结果表明,催化剂内部存在扩散阻力,随着反应进行,颗粒内物质由分层分布渐变为均匀分布。随机混合床与常规床相比,随机混合床稳态前热点不易波动、稳态产率更高,而柱形床径向热场更均匀且热点更高。在四种规则混合床中,底部为4孔的两种催化剂床相较于底部为柱形的两种催化剂床,整体流场更均匀、高速区少、压降大、高温区占比大、稳态前热点不易波动;2层-底4孔催化剂床的稳态出口CO2转化率和CH4产率均最大;4层-底4孔催化剂床高温区占比较高,随着反应进行,高温区占比呈上升趋势,CO2转化率和CH4产率大幅下降。

关键词: 填充床, 颗粒混合, 二氧化碳加氢, 甲烷化, 数值模拟, 离散元, 颗粒尺度