A Novel Approach to the Modelling of Transport Phenomena in Random Packings

Abstract

The separation characteristics of absorption columns are commonly predicted by simplified stage models (equilibrium or rate-based). Such models employ several parameters which have to be determined by experiments. This represents a major weakness of stage models, as, generally, these parameters are not directly transferable to different chemical systems or geometries. An alternative approach to the modelling of transport phenomena in fluid separation processes is based on so-called hydrodynamic analogies. Hereby, the actual flow in a packing is replaced by a combination of different, simplified flow patterns depending on the specific geometry of column internals. The transport of heat and mass in such flows can be described by rigorous conservation equations. As a consequence, the use of most of the above mentioned experimental parameters can be avoided. In this work, the hydrodynamic analogy approach is applied to random packings. To validate the model, the separation efficiency of Pall rings for the reactive absorption of CO2 into aqueous sodium hydroxide solution was investigated experimentally in an industrial-scale column. In this paper, the modelling method is described in detail and the validation of the simulation results is presented.