Models for Predicting Average Bubble Diameter and Volumetric Bubble Flux in Deep Fluidized Beds

Abstract

The average bubble diameter and volumetric bubble flux give indications about the overall bed expansion in a fluidized bed. As these properties depend on the particle properties and fluidized bed regime, their accurate predictions have been a challenge. A new set of models for predicting the average bubble properties within the bubbling and slugging regimes in a deep fluidized bed is proposed, where bubble flux is modeled by G = U − c( ) U U U a 0 mf 0 mf, bubble diameter is modeled by db̅ = 0.848G D 0.66 0.34 and transition velocity is modeled by = + φ − − − 1 2.33U ( c 1)( ) U U a h mf D 0.027 0.35 t 0.588 bs mf t 0 . he models are developed using the information obtained from an experimental setup equipped with a ualplane electrical capacitance tomography and a porous distributor plate. Although they are empirical, the proposed models are based on the two-phase theory used in describing the bubble flow in a fluidized bed. These models have been validated, and the results show that they can be used to predict the behavior in different regimes at different gas velocities.