Influence of interparticle forces on solids motion in a bubbling gas-solid fluidized bed

This article presents some observations of the effect of interparticle forces (IPFs) on solids motion in a gas-solid fluidized bed operated in the bubbling fluidization regime and at atmospheric pressure. The radioactive particle tracking (RPT) technique was adopted to observe the solids flow pattern and quantify spherical equivalent bubble size, distributions of upward and downward-moving clusters and idle and bubble-induced times, cycle frequency, and axial/radial solids diffusivities. The level of cohesive IPFs was increased and controlled in the fluidized bed with a polymer coating approach. Experimental results showed that the presence of IPFs could effectively modify the solids flow pattern in a bubbling gas-solid fluidized bed. The influence was more pronounced at low gas velocity, where the ratio of the magnitude of IPFs to hydrodynamic forces was high. At constant superficial gas velocity, beds with IPFs contained smaller bubbles indicating a higher tendency of gas entering the dense phase compared to the bubble phase. The different characteristic parameters of solids mixing showed that the favorable effect of IPFs on the division of the fluidizing gas between the bubble and dense phases was accompanied by reductions in the quality of global and local solids mixing. (C) 2016 Elsevier B.V. All rights reserved.