Investigation on drawdown process of light-floating particles in a pilot scale cup-shaped blade agitator

Abstract

The novel cup-shaped blade agitator with pilot scale was successfully applied in light-floating particles drawdown dispersion under high solid content (40 vt.%) for the first time. The drawdown dispersion effect of cup-shaped blade agitator was systematically investigated, by integrating the CFD simulation, the research unveils the impact mechanisms of flow conditions within the agitator on particle drawdown and dispersion, under various structural and operational parameters of the cup-shaped blade (CB) impeller. The optimum structure for CB was determined as CB2, with impeller deflection angle of -30°, and impeller diameter of 0.43 m. Under this structure, the CB agitator exhibits the best performance and can complete drawdown dispersion of light-floating particles at high solid concentration exceeding 40 vt.%. Besides, at lower solid particle volume concentration (Cv), both Njd and Pjd increase with increasing Cv. Interestingly, after Cv exceeds 10%, Njd and Pjd decrease as Cv continues to rise. Comparing with traditional impeller RT and PBT, the CB impeller is more competitive. Finally, dimensionless correlations of Njd and Pjd were established to provide practical guidance for application and optimization of CB agitator.