Experimentally Validated CFD Model for Gas-Liquid Flow in a Round-Bottom Stirred Tank Equipped with Rushton Turbine

Hydrodynamics of gas-liquid flow in a round-bottom stirred tank is modelled at two gas flow rates, constant bubble size and agitator speed of 300 rpm. A round-bottom tank equipped with four baffles and a Rushton turbine was chosen to represent a typical reactor used in hydrometallurgical processes operating under pressure. The applicability of different momentum interchange models and the Realizable k-epsilon, SST k-omega, and RSM turbulence models was studied using CFD software. The results were compared and validated against experimental data from Particle Image Velocimetry measurements by means of liquid and gas velocity distributions. In addition, energy balance between power input and dissipation energy was compared for the different turbulence models. The CFD model was found to be in good agreement with the measurements. Of the turbulence models studied, the Realizable k-epsilon model showed best agreement with the measured velocity profiles. Popular drag force models proposed in the literature were assessed, as was the influence of inclusion of non-drag forces. Gas flow was found to affect the liquid phase flow in the tank by generating an additional secondary circulation loop in the upper part of the reactor.