Numerical Simulation of Trickle-Bed Reactor Hydrodynamics with RANS-Based Models Using a Volume of Fluid Technique

A trickle-bed reactor (TBR) was modeled by means of the volume of fluid (VOF) model to provide a hydrodynamic behavior analysis in trickling flow conditions. Fluid dynamics of the TBR is characterized by poor liquid distribution and inefficient catalyst utilization and conventional modeling techniques are unable to address these key design issues. Therefore, the VOF code was used to investigate the major hydrodynamic parameters in a three-dimensional packed bed providing a more rigorous physical description of the underlying flow process. Several numerical solution parameters including different mesh densities, time steps, and convergence criteria were optimized in order to provide computational independent results. During the parametric optimization it was found that the VOF model is more sensible to mesh density and time step than with respect to convergence criteria. The computational fluid dynamic model was thoroughly validated by comparing the model predictions with the published experimental data for liquid holdup and two-phase pressure drop. After the VOF optimization, selected values for the numerical solutions parameters were used to perform the assessment of different turbulent flow models at two nominal gas flow rates. Afterward, several computational runs were performed in the evaluation of the influence of either gas or liquid flow rate on TBR hydrodynamics.