Modeling and Simulation of Hydrodynamics and Filtration in a Membrane‐Assisted Stirred Slurry Reactor

Abstract

A membrane‐assisted stirred slurry reactor is developed by equipping a membrane tube into a stirred tank. Liquid‐solid flow is simulated by the Euler‐Lagrange method with filtration and particle deposition models. Acceptable predictions on the cake mass and particle deposition patterns are achieved by comparing with experimental data. The introduction of the membrane tube generates an asymmetric flow field. Shear stress on the membrane surface has a direct influence on the particle deposition. Increasing the impeller rotating speed leads to larger shear stress and mitigates the particle deposition. The cake mass is reduced by placing the membrane tube close to the impeller. The upward liquid flow pumped by the pitched‐blade impeller results in low shear stress and the vertical‐blade impeller is preferable.

Effects on the Performance of Filtration in a Constant-Pressure Stirred Membrane Reactor

“…The study by Chen et al showed that the enhanced rotary tangential flow was beneficial in the shedding of deposited particles and the reduction of cake resistance. In addition, the studies of semicontinuous membrane reactors showed that the stirring rate had a nonlinear relationship with the membrane filtration performance, and the stirring rate was mostly set at 0 rpm in the membrane separation process. , Later, Qiu et al used the multiphase particle-in-cell method combined with the force equations of particles to calculate the deposition rate and found that increasing the shear rate on the membrane surface could effectively reduce particle deposition, while the axial flow along the membrane bundle cannot control membrane fouling. However, the filtration did not reach the quasi-steady state.…”

Study on the Membrane Fouling Process and Mechanism of Constant Pressure Filtration in Stirred Membrane Reactors

“…The closer the membrane tube was to the junction of the forced vortex and the free vortex, the higher the membrane flux was. Experiments and simulations by Qiu et al 12 had shown that using straight-blade impellers, increasing the impeller velocity, and moving the membrane tube close to the impeller could increase the shear stress and reduce membrane fouling. It is generally accepted that increasing the shear stress enhances the turbulence and instability of the fluid, thereby promoting the migration of particles on the membrane surface, which can effectively reduce membrane fouling.…”