Back Flow Rate and Exchange Rate of Liquid in a Vertical Stirred Vessel with Six Multiple Impellers

Abstract

In applying backmixing model for liquid mixing characteristics of vertical stirred vessels with six multiple impellers and perforated-type partition plates, the effect of the opening ratio of the perforated-type partition plate and the stirring speed on the back flow rate and the exchange rate of liquid was experimentally investigated. The vessel diameter D_T was 0.10 m and the impeller diameter D_i was one-half of the vessel diameter D_T. In the vertical stirred vessels with six multiple impellers, the relationship among the back flow rate f, the feed flow rate q and the exchange rate Q was established f=Q−q/2. The exchange rate Q increased in proportion to the stirring speed of impeller n and the opening ratio of a perforated-type partition plate A_r. When the agitated Reynolds number N_Re is greater than 4×10³, the value of the modified dimensionless exchange rate Q/(nD_i³Ar) was almost constant at 0.20.