A microscopic study on the mixing process of binary solids in bubbling fluidized bed

Abstract

A novel method for measuring the micro mixing ratio of binary solids in dense fluidizations is developed. The mixing process within a bubbling fluidized bed that can be assumed as one mixing cell is resolved. Dispersion coefficient and mixing index methods are applied to characterize the mixing process. Results show that diffusion has an important effect on mixing at the bottom and top of the fluidized bed. Meanwhile, convection is the principal mechanism of mixing at the center. The lateral micro dispersion coefficient is between 0.005 m/s and 0.03 m/s. The vertical micro dispersion coefficient is approximately twice as that in the lateral direction. A new mixing index is proposed to evaluate the micro mixing quality of binary solids. The time required to reach uniform mixing in the lateral direction is more than twice as that in the vertical direction.