Solids Suspension Study in a Side-Entering Stirred Tank Through CFD Modeling

Abstract

Abstract Computational fluid dynamics (CFD) technique was employed to study solids suspension in a stirred tank equipped with three side-entering impellers. Simulations of solid–liquid flow were performed by using an Eulerian-Granular Multiphase (EGM) model coupling with standard k–ε mixture turbulence model and Reynolds stress model, respectively. A multiple reference frame (MRF) approach was used to model the impeller rotation. The CFD predictions have been verified by comparing the predicted results with the experimental just suspended impeller speed and solid sediment pattern at the tank bottom. The solid distribution and liquid-phase velocity vectors throughout the tank for two cases with and without solid phase were investigated to understand the characteristics of solid–liquid flow. The solid suspension quality has been assessed by employing three criterions: the just suspended impeller speed Njs, cloud height h, and suspension homogeneity. The effects of impeller agitation speed, particle size, and solid loading on suspension quality have been investigated. The computational model and results discussed in this study would be useful to understand the solid–liquid dispersion process in side-entering stirred tanks and extend the application of CFD models for equipment design and process optimization.