Mixing/segregation characteristics and bubble behaviors of density-segregated binary particles in a pressurized fluidized bed

Abstract

To enhance comprehension and achieve more targeted optimization of pressurized fluidized beds, experiments were carried out in a “cold” pseudo 2D pressurized fluidized bed with binary mixtures differing in densities via high-speed digital image analysis. The impacts of operating pressure and gas velocity on fluidization pattern, mixing/segregation characteristics, and bubble behaviors were comprehensively analyzed. Results show that the fluidization of binary mixtures is a gradual process which occurs within the range between the minimum fluidization velocity of flotsam and jetsam components. Particles with lighter density tend to produce larger size of bubbles, larger bubble fraction and increased fluctuation compared to the heavier ones when particle sizes are similar. Increasing the pressure results in an overall decreased bubble diameter and bubble fraction, which prohibits the bubble-particle interaction and ultimately deteriorates the mixing quality. The carried-out whole-field, non-intrusive measurements in this work would provide the much-needed database for validation of CFD models.