Moghaddam Elyas M, Foumeny Esmail A, Stankiewicz Andrzej I, Padding Johan T
Process & Energy Department, Delft University of Technology, 2628CB Delft, The Netherlands.
Ind Eng Chem Res. 2018 Nov 7;57(44):14988-15007. doi: 10.1021/acs.iecr.8b03915. Epub 2018 Oct 11.
Despite the common use of nonspherical catalyst pellets in chemical engineering applications, the packing structures of such pellets have not been as systematically studied and characterized as spherical packings. We propose a packing algorithm based on rigid body dynamics to simulate packing of nonspherical and possibly nonconvex pellets. The algorithm exerts a hard-body approach to model collision phenomena. The novelty is that the transition between moving and resting particles is controlled by a cutoff on the relative contact velocities, instead of artificially damping linear and angular velocities to stabilize the algorithm. The algorithm is used to synthesize packings of spheres, cylinders, and Raschig rings with tube-to-pellet diameter ratios 3-9.16. The packings are validated in terms of bulk porosity and radial void fraction distribution, finding satisfactory agreement with literature data. Denser packing structures are generated with high restitution coefficients and low friction coefficients. The confining tube walls play an important role, with highly fluctuating bulk porosities in narrow tubes.
尽管在化学工程应用中非球形催化剂颗粒使用普遍，但此类颗粒的堆积结构尚未像球形填料那样得到系统的研究和表征。我们提出一种基于刚体动力学的堆积算法，以模拟非球形且可能非凸形颗粒的堆积。该算法采用刚体方法来模拟碰撞现象。其新颖之处在于，运动颗粒与静止颗粒之间的转变由相对接触速度的截止值控制，而不是通过人为地衰减线速度和角速度来稳定算法。该算法用于合成球体、圆柱体以及管与颗粒直径比为3 - 9.16的拉西环的堆积。这些堆积在体孔隙率和径向空隙率分布方面得到验证，与文献数据吻合良好。具有高恢复系数和低摩擦系数时会生成更致密的堆积结构。限制管壁起着重要作用，在狭窄管中体孔隙率波动很大。
