Model based random packing optimisation for absorption processes using the hydrodynamic analogy concept

Abstract

A novel approach is presented that supports the development of new packing types for absorption processes by “virtual experiments”. Based on a hydrodynamic analogy model for the absorption in random packed beds, a simulation study highlighting the influence of packing geometry on separation efficiency is performed. In the model, the liquid flow is reproduced by film, jet and droplet flow patterns with countercurrent gas flow. To incorporate the actual redirection of liquid and gas flow inside the packing, these flows are mixed after specific lengths of undisturbed flow. The lengths are derived from the packing geometry. These lengths as well as the hold-up ratios for the liquid flow patterns and the hydraulic diameter of the packed bed are varied in the simulation study. It is found that a small hydraulic diameter, an increased frequency of liquid film mixing and an increased film hold-up lead to higher absorption rates. In contrast, the frequency of gas or jet/droplet mixing has negligible influence.