Mechanism of solid segregation in gas fluidised beds.

Abstract

Cine-photographic measurements were made on the solid movements induced by a single bubble passage through a two-dimensional gas-fluidised bed of 0.163 mm glass beads which contains recognisable aggregates of bigger or heavier particles, i.e., jetsam. Though all particles near the bubble were shown to flow in a streamline motion, jetsam descent occurred relative to the bulk particles. The net descending distance of jetsam was obtained from the difference between the drift lines of the jetsam and of the bulk particles. The average descending distance over the bubble cross-sectional area was shown to depend on the jetsam properties. Based on the results, average descending velocities were also calculated and compared with a simple model. (A)