Evaluation of multiphase CFD models in gas–liquid packed-bed reactors for water pollution abatement

Abstract

The present work encompasses an assessment of multiphase fluid modelling techniques to allow the prediction of reaction parameters in trickle-bed reactors (TBR). After the development of volume-of-fluid (VOF) and an Euler–Euler models, the catalytic wet air oxidation of phenolic acids was simulated under unsteady state evaluating axial and radial profiles for total organic carbon concentration and temperature for the bulk phase. For the purpose of code validation, theoretical results were compared with experimental data in terms of major hydrodynamic parameters, pressure drop and liquid holdup. The Euler–Euler model gave better predictions in comparison with VOF model since it used empirically based interphase coupling parameters in the momentum balance equation. After the hydrodynamic validation, both multiphase models were used to investigate the dynamic performance of TBR under reaction conditions for the pollutant decontamination of phenolic wastewaters. VOF exhibited the highest TOC conversion as well as the highest temperatures. The Euler–Euler model predictions gave rise also to the existence of hotspot formation in the first half of TBR being this fact related with poor radial mixing attained by means of CFD codes.