Experimental segregation profiles in bubbling gas‐fluidized beds

Abstract Species segregation measurements were performed in a fluidized bed composed of a binary, Geldart B mixture. Three system types were explored: size segregation, density segregation, and combined size/density segregation (with the smaller species denser and lighter). Glass and polystyrene mixtures were investigated, at various gas velocity, jetsam concentration, particle‐size ratio, particle‐density ratio, and bed‐aspect ratio combinations. Axial and radial segregation profiles were obtained from frozen bed sectioning. Low‐velocities were used in order to minimize the possibility of segregation during bed collapse. In size‐segregating systems, coarse particles act as jetsam, with a nearly constant concentration of fines in the flotsam‐rich section. For density segregation, heavier particles act as jetsam and segregation behavior is not monotonically dependent on bed composition. A slight radial segregation was observed at all gas velocities, with jetsam accumulating near the wall. In size‐and‐density‐segregating systems, denser particles (smaller and lighter) act as jetsam, with a slightly higher jetsam accumulation near the core of the bed. At higher gas velocities, however, the bottom layers become richer in jetsam in the periphery. Collectively, the data provide a robust experimental data set for evaluating the ability of existing and new models to predict species segregation. © 2007 American Institute of Chemical Engineers AIChE J, 2007