Effect of Operating Parameters on the Mixing Performance of the Superblend Coaxial Mixer

Abstract

The mixing performance of a Superblend coaxial mixer, which combines a Maxblend impeller as the central impeller and a helical ribbon, was investigated experimentally in terms of power consumption and mixing time. The objective was to better understand the influence of the operating conditions on the mixing performance with Newtonian fluids. The experiment setup used allows each shaft to be driven independently. Taking advantage of individual torque-meter on each shaft and a well-developed decolorization technique, it was shown that the speed ratio RN (NMaxblend /Nhelical ribbon = 1, 2, 4, 6, 8) and the rotating mode (up- and down-pumping of the helical ribbon) have the largest influence on the mixing performance and that there is no universal operating mode for minimizing power and mixing time in all conditions or flow regimes. The results are presented in terms of the power consumption and mixing time throughout the laminar, transitional, and turbulent regimes. The contribution of each impeller, the variation of flow patterns, the determination of the optimal operating conditions, and the comparison of power constant are discussed.