Unconventional Configuration Studies to Improve Mixing Times in Stirred Tanks

Dynamic perturbations and off‐centered single and dual mixing impeller configurations have been investigated to reduce mixing time with viscous fluids. Mixing times, measured with a color‐discoloration technique based on a fast acid‐base reaction, reveal the presence of both segregated and dead zones. A statistical design approach has been used to evaluate the effect of the impeller position as well as the dynamic conditions. Homogenization is significantly enhanced when a radial flow impeller is used under both off‐centered and dynamic perturbation conditions. In the case of an axial flow impeller, a combination of long clockwise times and short counter‐clockwise times give better mixing times. An enhanced homogenization is also observed when a dual impeller configuration is used.