Application of CFD to improve calculated process of methanation over plum-shaped catalyst

doi:10.11949/j.issn.0438-1157.20180104

Abstract

Abstract:

The simulation of methanation process is studied by CFD, and makes reasonable improvement to the model. The three-dimensional model of methanation reaction on the plum-shaped catalyst was established and the validity of the model was verified. Due to strong diffusion limitations the CO concentration of catalyst particles has great difference between the internal and external. Inside the catalyst, reaction conditions are changed to be a high H/C value. The diffusion rate of H₂ is larger than CO. A single kinetics can't describe the reaction accurately. The catalyst domain is divided into two parts according to the variety of CO concentration in catalyst, and different kinetics is applied into the corresponding domain. Under the control of two kinetics, the average reaction rate of methanation has been accelerated, which is closer to the actual process and show that the new model is more accurate.

Key words: methanation, computational fluid dynamics, catalyst, optimal design, diffusion

摘要：

对合成气甲烷化反应体系进行CFD（计算流体动力学）计算，并对模型提出合理的改进。通过建立合理的甲烷化梅花状催化剂颗粒三维模型进行计算，并验证了模型的有效性。结果表明：甲烷化反应内扩散阻力很大，CO在催化剂表面与内部存在明显的浓度差。且H₂与CO扩散速率不同，导致催化剂内部的氢碳比很高，内部的反应条件与催化剂表面相比发生改变，使用单一的动力学方程无法准确描述实际的反应过程。因此，提出对催化剂的不同区域分别讨论，根据催化剂内CO含量的变化将两种不同的动力学方程分别应用在催化剂的不同区域。计算后发现采用两种动力学控制下催化剂内甲烷化反应的平均反应速率加快，反应进行的程度变大，更加接近实际过程，提高了计算的精确性。

关键词: 甲烷化, 计算流体动力学, 催化剂, 优化设计, 扩散

CLC Number:

TQ021.4

ZHANG Jie, LI Tao. Application of CFD to improve calculated process of methanation over plum-shaped catalyst[J]. CIESC Journal, 2018, 69(7): 2985-2992.

张杰, 李涛. 甲烷化梅花状催化剂CFD计算及改进[J]. 化工学报, 2018, 69(7): 2985-2992.

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