Modified Force Balance Model of Estimating Agglomerate Sizes in a Gas–Solid Fluidized Bed

Abstract

Transient signals of an optical probe were registered in a gas–solid fluidized bed dealing with four kinds of particles, respectively. Particle agglomerates were identified, and the diameters were investigated. The force balance model and the energy balance model are analyzed, but the predictions underestimate the agglomerate diameter because of unsuitable assumptions for FCC particle-formed agglomerates. A modified force balance model is proposed on the basis of imperfect elastic collision, and the restitution coefficient is considered and calculated when calculating the collision force. The predictions are in great agreement with experimental results. A criterion of agglomerate coalescence and breakup is proposed. The effect of the ratio of the diameters of two collision agglomerates is discussed, and the critical ratio for agglomerate coalescence is calculated. The agglomerate strength and tensile stress are calculated, and the agglomerate strength is always greater than the tensile stress, which indic...