CFD simulation of solid–liquid stirred tanks

Abstract

Solid–liquid stirred tanks are commonly used in the minerals industry for operations like concentration, leaching, adsorption, and effluent treatment. Computational fluid dynamics (CFD) is increasingly being used to predict the hydrodynamics and performance of these systems. Accounting for the solid–liquid interaction is critical for accurate predictions. Therefore, a careful selection of models for turbulence and drag is required. In this study, the effect of drag model was studied. The Eulerian–Eulerian multiphase model is used to simulate the solid suspension in stirred tanks. Multiple reference frame (MRF) approach is used to simulate the impeller rotation in a fully baffled tank. Simulations are conducted for concentration 1% and 7% v/v and the impeller speeds above the “just suspension speed”. It is observed that high turbulence can increase the drag coefficient as high as forty times when compared with a still fluid. The drag force was modified to account for the increase in drag at high turbulent intensities. The modified drag is a function of particle diameter to Kolmogorov length scale ratio. The modified drag law was found useful to simulate the low solids holdup in stirred tanks. The predictions in terms of velocity profiles and the solids distribution are found to be in reasonable agreement with the literature experimental data.

@article{wadnerkar2012apt,
  title         = {CFD simulation of solid--liquid stirred tanks},
  author        = {Wadnerkar, Divyamaan and Utikar, Ranjeet P. and Tade, Moses O. and Pareek,
                  Vishnu K.},
  year          = 2012,
  journal       = {Advanced Powder Technology},
  publisher     = {Elsevier},
  volume        = 23,
  number        = 4,
  pages         = {445--453},
  doi           = {10.1016/j.apt.2012.03.007},
  url           = {https://www.sciencedirect.com/science/article/pii/S0921883112000386}
}