Design of Self-Aerating Unbaffled Stirred Tank with Concave Blade Impeller

Experimental investigation was done in unbaffled self-aerating stirred tanks using concave blade impeller to analyze the mass transfer, power number and vortex depth. Experiments were done with varied impeller diameter to tank diameter and impeller clearance. Scale-up criteria were developed for mass transfer rate for different impeller clearance with varied impeller to tank diameter. The prediction capability of the criteria is found to be satisfactory. The results show that the power number is dependent on the impeller to tank diameter ratio and impeller clearance as well. Scale-up criteria for relative vortex depth were also developed. Single- and multiphase modeling was done by employing computational fluid dynamics (CFD) techniques to observe characteristics of flow pattern transition and a qualitative analysis of mass transfer rate, respectively.