Simulation of Fluid Mixing Enhanced by Rigid-flexible Impeller in Stirred Tank
1. Department of Biochemical and Chemical Engineering, Chongqing Industry & Trade Polytechnic College, Chongqing 408000, China;
2. School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
Abstract Mechanical agitation is an important mixing technique with a wide range of industrial applications. Clarification of the flow field in the stirred reactor contributes to the directional regulation of the mixing process. Therefore, the numerical simulation method was used to study the flow field in the stirred tanks with rigid impeller and the rigid-flexible impeller, respectively. The axial velocity profile, velocity field, impeller trailing vortex and turbulence kinetic energy in the stirred tank were analyzed. The effects of impeller type, rotation speed, diameter of impeller and off-bottom clearances on the flow field were investigated. Results showed that the axial velocity and high-speed flow region of rigid-flexible impeller system were larger than those of rigid impeller system. And the impeller trailing vortex was larger than the other system. It also suggested that higher rotational speed and larger impeller diameter made good to fluid mixing. The excessively high or low off-bottom clearances were not conducive to fluid mixing. In conclusion, rigid-flexible impeller has significant intensification effect on fluid mixing compared to rigid impeller.
