Investigation of liquid maldistribution in trickle-bed reactors using porous media concept in CFD

Abstract

A three-dimensional CFD model for simulating two-phase flow in trickle-bed reactors (TBRs) is presented. Based on porous media concept, a two-phase Eulerian model (rather than computationally demanding traditional three-phase Eulerian model) describing the flow domain as porous region is presented to understand and forecast the liquid maldistribution in TBRs under cold-flow conditions. The drag forces between phases have been accounted by employing the relative permeability concept [Sàez, A. E., Carbonell, R. G., 1985. Hydrodynamic parameters for gas–liquid cocurrent flow in packed beds. A.I.Ch.E. Journal 31, 52–62]. The model predictions are validated against experimental data reported in literature, notably using the liquid distribution studies of Marcendelli [1999. Hydrodynamique, Transfert de Chaleur Particule-Fluide et Distribution des phases dans les Reacteurs a lit Fixe a Ecoulement a Co-courant Descendant de Gaz et de Liquide. Doctoral Thesis. INPL, Nancy, France]. Various distributor configurations reported therein have been recreated in the CFD model and sensitivity studies have been performed. Good agreement is obtained between the reported experimental results and this proposed first-principle based CFD model. Finally, the concept of distribution uniformity is discussed and applied to the CFD model predictions. The CFD model is subjected to a systematic sensitivity study in order to explore better liquid distribution alternatives.