Predicting Influence of Packing Shape and Loading Methodology upon Fixed-Bed Structures
Srikanth Panyaram (1), Benjamin Wilhite (1)
1. Department of Chemical Engineering, Texas A&M University
Fixed beds are ubiquitous in chemical industry, finding use for gas-solid, liquid-solid, gas-liquid solid catalytic as well as gas-liquid mass transfer processes (absorption, distillation). The local packing structure of the fixed-bed provides surface area for fluid mass transfer, house catalyst material for reactions and dictates local flow patterns. Heterogeneities in packing configurations may result in increased pressure drop, fluid maldistribution and/or under-utilization of catalyst material, making an understanding of packed-bed structure essential to the efficient operation of these units.
Bed-packing algorithms have been developed for generating detailed three-dimensional maps of local bed structure. The algorithm has been tailored to study two widely used shapes in industry; spheres and cylinders. The study provides important insights into the global and local properties of the fixed-bed as a function of particle size, shape and loading methodology. Shape and size distribution of the particle sample influences the global and radial voidage. An essential component of this study is to understand how loading methods can influence the evolution of the properties exhibited by the beds. Different loading methods have been used to study the influence of particle-particle and particle-wall interactions. These interactions have shown to influence the voidage and orientation effects within the packing structures. Finally, the effect of these parameters on the evolution of fluid flows in fixed beds is elucidated. These investigations help in developing tools to manipulate the heterogeneities in packed beds to enhance reactor performance.
Keywords: Fixed Bed, Packing, Catalyst