异形催化剂床层中Sabatier反应的微-介尺度模拟

采用离散元方法（DEM）建立随机堆积球形、柱形催化剂床层，计算流体力学（CFD）方法模拟Sabatier反应床层介尺度和催化剂微尺度的温度和物质浓度分布，并探讨了催化剂形状、壁温和入口条件对反应特征的影响。结果表明：床层中会出现球形热点区，并随反应进行向出口移动，催化剂外层反应物浓度比内层高且呈环状分布。柱形催化剂单颗粒中心CO₂转化率较球形高，但棱角和床层壁面会出现低转化率区，床层流体会出现回流、滞留和沟流现象，最终导致CO₂转化率为球形>柱形（径高比=1.3）>柱形（径高比=1）。球形催化剂床层中，时间t=200s时，CO₂转化率达到峰值26%，若此时将壁温降低50K，时间t=500s时，较降温前CO₂转化率增大2%、热点温度降低10K；增加惰性球层、减小入口流速和温度，能提高催化剂内CO₂转化率。

Micro-mesoscale simulation of Sabatier reaction in different shapes catalyst bed

Discrete element method (DEM) was used to establish random stacking spherical and cylindrical catalyst bed. Computational fluid dynamics (CFD) method was used to simulate the Sabatier reaction temperature and concentration distribution of fixed-bed and catalyst. Catalyst shape, wall temperature and inlet condition on the reaction characteristics effect was discussed. The results show that spherical hot point region will appear in the bed and move to the outlet as the reaction proceeds. Reactant concentration in the catalyst outer layer is higher than the inner layer and has a circular distribution. CO₂ conversion in cylindrical catalyst center is higher than that in spherical catalyst center, but there will be a low conversion region in the catalyst angle and fixed-bed wall, and the reflux, retention and trench flow will occur in the bed. As a result, CO₂ conversion is spherical>cylinder (diameter to height ratio=1.3)>cylinder (diameter to height ratio=1). In the spherical catalyst bed, CO₂ conversion reaches the peak of 26% at 200s. If the wall temperature decreases by 50K at 200s, CO₂ conversion will increase by 2% and the hot spot temperature decrease by 10K at 500s. Increasing the inertia sphere and reducing the inlet flow rate and temperature can increase catalyst CO₂ conversion.