An experimental study of the effect of collision properties on spout fluidized bed dynamics

In this paper we experimentally study the effect of collision properties of different particle systems on the bed dynamics of a spout fluidized bed. This is done for different flow regimes: the spout-fluidization regime (case A), the jet-in-fluidized-bed regime (case B) and the spouting-with-aeration regime (case C). The considered particle systems comprise glass beads, γ-alumina oxide and zeolite 4A particles, which are all classified as Geldart D. A non-intrusive measurement technique is used, viz. particle image velocimetry (PIV) to measure the particle flow field in a pseudo two-dimensional (2D) spout fluidized bed. Additionally, digital images are analyzed using a newly developed digital image analysis (DIA) algorithm to evaluate the particle volume fraction. It is demonstrated that the new proposed DIA algorithm provides reliable information on the particle volume fraction distribution, showing that it is a powerful tool when combined with PIV. The added value of DIA is confirmed by comparing the particle velocity fields and volumetric particle fluxes. The effect of the collision properties for glass beads, γ-alumina oxide and zeolite 4A particles has been studied in three flow regimes, i.e. the intermediate/spout-fluidization regime (case A), the jet-in-fluidized-bed regime (case B) and the spouting-with-aeration regime (case C). For each flow regime, the particle volume fraction shows small differences between the different particle systems. For the γ-alumina oxide and zeolite 4A particles, the spout channel is less stable for the cases A and C. The particle fluxes display also small differences between the particle systems for each flow regime.