Research of the liquid-phase flow field in a multi-impeller stirred tank

ZHANG Cui-xun

(Tianli Drying Equipment Incorporated Company, Shandong Province Academy of Sciences, Jinan 250014, China)

Abstract: Aiming at optimizing the configuration of a multi-impeller stirred tank, the turbulent liquid-phase flow fields in a stirred tank agitated by multiple Rushton impellers were simulated using the computational fluid dynamics (CFD) technique. Firstly, the flow field in a liquid height to tank diameter ratio H/T=1.4 stirred tank agitated by dual-Rushton impellers was studied and compared with the experimental result available in the literature. Reasonable agreement between the experimental and numerical results indicates the validity of the CFD model. Subsequently, effects of off-bottom clearance of the lower impeller, adjacent impeller spacing, impeller to tank diameter ratio, and impeller number on the flow field,turbulent kinetic energy and power consumption in an H/T=1.6 elliptical-bottom multipleRushton impeller stirred tank were comprehensively investigated. The results indicate that, for the stirred tank studied here, dual-impeller with the impeller to tank diameter ratio D/T=0.48 and off-bottom clearance of the lower impeller C1=0.4T is the best configuration. Under the condition of the same reynolds number, it has the merit of generating a more homogeneous turbulence field and consuming lower power.