Solid-liquid mixing characteristics in a fractal cut impeller stirred reactor with dense solid loading

Abstract

The fractal cut impeller (FC impeller) based on fractal iteration of “H” pattern cuts on the impeller blades was introduced in the solid-liquid system with dense solid loading. The solid-liquid mixing characteristics in a stirred tank with pitched blade impeller (PB impeller) and FC impeller were comparatively investigated with experiment and numerical simulation. Results showed that FC impeller exhibited lower power consumption (P) and power number (Np) compared to PB impeller at the same impeller speed. It could be also observed that increasing the fractal iteration number of FC impeller led to a further decrease in P and Np. Meanwhile, FC impeller could reduce the size of impeller tailing vortex, enhance turbulent intensity and turbulent kinetic energy dissipation rate, and improve solid particle suspension quality compared to PB impeller under the constant power consumption, and an increase in fractal iteration number of FC impeller resulted in higher solid particle suspension efficiency. In addition, it was also found that the fractal arrangement of cuts on the impeller blades could increase turbulent intensity, enhance turbulent kinetic energy dissipation rate and facilitate an improvement in solid particle suspension quality as compared to a whole cut on the impeller blades with equal cut area.