Effect of bed density on the segregation behavior of fine coal particles (<6 mm) in a gas–solid separation fluidized bed

In this paper, the segregation behavior of fine particles with different densities in a gas–solid separation fluidized bed with Geldart B particles acting as the fluidized medium was studied. The variation characteristics of the bed density and bubble behavior under different operating gas velocities were studied by analyzing the pressure drop signal occurring within in the bed. The results showed that there was an evident backmixing phenomenon of feed composed of single and mixed particles in a gas–solid fluidized bed, and the total misplaced material rate reached 45.8%, 46.12% and 44.48%, indicating that the feed could not achieve a good segregation effect according to the bed density. The mixing effect of feed particles first increased and then decreased with increasing operating gas velocities. However, it is worth noting that the gas–solid fluidized bed system still had a good segregation effect for feed particles with densities higher than the bed density.