Numerical simulation for a punched impeller in a solid-liquid stirred tank based on the EE-KTGF model

Abstract

The improvement of mixing efficiency in a solid-liquid stirred vessel is one of the important challenges in industrial processes. The present study aims at evaluating the performance of the punched impeller. The mixing process in a stirred tank with the down-pumping pitched blade turbine (PBTD) and down-pumping pitched blade punched turbine (PPBTD) was predicted adopting the Eulerian–Eulerian method combined with kinetic theory of granular flow (EE-KTGF). The flow field and solid particles distribution of two impellers were compared in detail through various parameters. It was found that that the PPBTD impeller has positive significance in improving suspension quality and reducing power consumption. Moreover, the effects of aperture diameter, aperture ratio, and liquid viscosity on mixing characteristics were discussed. It can be observed that the PPBTD impeller can effectively enhance the mixing degree of liquid with different viscosity. The aperture diameter and aperture ratio have great influence on turbulence parameters, solid particles distribution, and power consumption. The better suspension quality can be obtained, and power consumption was dramatically decreased by 7.1% when the aperture diameter and aperture ratio are 8 mm and 13%, respectively. These results can be the significant guidance to the design of the punched impeller in chemical and biochemical engineering applications.