Grid-Zone Particle Hydrodynamics and Solid Circulation in a Multiple Jet Fluidized Bed

Particle Image Velocimetry (PIV) and Digital Image Analysis (DIA) were used to investigate the evolution of multiple inlet gas jets located at the distributor base of a two-dimensional fluidized bed setup. Experiments were conducted with varying distributor orifice diameter, orifice pitch, particle density, particle diameter, and fluidization velocity to understand the motion of particles in the grid-zone region of a fluidized bed. Results were used to develop a phenomenological model that quantifies the conditions throughout the entire grid-zone. The results and the model were further analyzed to understand the effect of operating conditions on the solid circulation dynamics of a multiple jet system fluidized bed. It was determined that the solid circulation rate increased linearly with an increase in the fluidization velocity until the jet system transitioned from isolated to an interacting system. The solid circulation increased at a much lower rate in the interacting system of jets. This sudden change in the solid circulation rate has not been reported in the literature possibly due to the lack of multiple jet studies. For multiple jet systems, this phenomenon may indicate the presence of an optimum operating condition with high circulation rate and low air input in the bed.