On the roles of interstitial liquid and particle shape in modulating microstructural effects in packed-bed adsorbers

Artikel i vetenskaplig tidskrift, 2022

Several industrial applications use packed-bed reactors for heterogeneous processes with intermittent presence of interstitial liquid. One such example is steam-regenerated adsorption systems. Here, we computationally generate two randomly packed beds of the same voidage – one with spheres and one with cylinders – to study the role of particle shape in such a process. We analyze the geometrical characteristics and determine the flow, transport and reaction properties at the same driving pressure difference. We also establish the effect of liquid on these characteristics. The bed of spheres exhibits 69% higher permeability due to differences in microstructure, and its shorter retention time and lower specific surface yields lower conversion in a first-order heterogeneous reaction. However, at the same flow rate, the spheres could be expected to outperform the cylinders. The bed of cylinders exhibits more pronounced local concentration variations due to a dominance of smaller pores, which are not as readily accessible to the flow. The presence of interstitial liquid reduces the permeability and significantly changes the streamwise velocity distributions inside both beds, effectively homogenizing the geometries by filling up the smaller pores. The implications of the present findings for reduced-order modelling of packed-bed adsorbers are discussed.