缠绕管式固定床反应器压降模拟与实验研究

Simulation and experiment of pressure drop in tube-wound fixed-bed reactor

针对装填不同形状颗粒的缠绕管式固定床反应器,建立颗粒床层的物理模型,通过CFD-DEM(计算流体力学-离散元法)耦合模拟的方法,探究颗粒形状和缠绕管结构参数对床层空隙率、流体分布的影响,利用缠绕管式固定床反应器实验台对高雷诺数单相流动状态下的压降进行精确测量。结果表明:缠绕管螺距、层间距越小,床层空隙率越大,管径的变化对空隙率几乎没有影响。球形颗粒床层的流场分布差异较大,圆柱、棱柱颗粒床层流体分布均匀性依次改善。球形颗粒的CFD-DEM耦合模拟结果与实验结果吻合较好,但是非球形颗粒的模拟结果与实验结果存在一定误差。对多种压降预测公式进行对比,最后根据实验结果对常用的Ergun公式、Nemec-Levec公式进行常系数项修正来准确预测压降,研究结果可为缠绕管式固定床反应器设计和压降预测提供参考。

The physical model of the particle bed was established based on a tube-wound fixed-bed reactor filled with particles of different shapes,and the effects of particle shape and structural parameters of the twisted tube on the bed void fraction and fluid distribution were investigated by means of CFD-DEM coupled simulation.The pressure drop in single-phase flow with high Reynolds number was measured accurately using the experimental bench of the tube-wound fixed-bed reactor.The results show that the smaller the twisted tube pitch and layer spacing,the larger the bed void ratio,and the change of tube diameter has almost no effect on the void ratio.The difference in the flow field distribution of the bed of spherical particles is large,and the uniformity of the fluid distribution in the bed of cylindrical and prismatic particles improves in turn.The CFD-DEM coupled simulation results of spherical particles are in good agreement with the experimental results,but the non-spherical particles have some errors with the experimental results.Various pressure drop prediction formulas are compared,and in order to accurately predict the pressure drop,the coefficients of the commonly used Ergun′s formula and Nemec-Levec′s formula are corrected according to the experimental results.The results of the study can provide a reference for the design and pressure drop prediction of tube-wound fixed-bed reactors.