Mixing optimization with inward flow configuration contra-rotating impeller, baffle-free tank

Abstract

In this study, pitched-blade, contra-rotating impeller, baffle-free tank with opposing inward flow is optimized using various designs of mixers derived from the Taguchi method. Mixing efficiency and torque are used to find the optimal design for the different specific gravities of solid particles employing in both experiments and CFD simulations. The analysis of signal-to-noise ratio shows that the impeller clearance and diameter are significant factors on the fluid flow and thus the mixing efficiency. In this study, 27 cases were studied to determine and report the optimal design parameters. A combination of CFD simulation with a strong design of experiment illustrates the ability to characterize and optimize the design parameters that affect mixing efficiency, showing promise as design guideline for the contra-rotating impeller. The best compromise between high mixing efficiency and low torque for pilot scale was found in the following configuration: a 300 mm diameter tank with liquid filled to a height of 300 mm; four pitched-blades rotating at 100 RPM with an impeller diameter of 150 mm; and a 125 mm impeller-impeller and impeller-bottom clearance.