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Transition velocities and phase holdups at minimum fluidization in gas–liquid–solid systems
Author(s) -
Lee Donghyun,
Macchi Arturo,
Epstein Norman,
Grace John R.
Publication year - 2001
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450790416
Subject(s) - fluidization , silicone oil , materials science , superficial velocity , phase (matter) , polystyrene , spheres , chromatography , mechanics , thermodynamics , fluidized bed , chemistry , analytical chemistry (journal) , polymer , flow (mathematics) , composite material , physics , organic chemistry , astronomy
Hydrodynamic experiments were performed using a 127‐mm diameter column with 3.2‐mm porous alumina, 3.3‐mm polymer blend, 5.5‐mm polystyrene and 6.0‐mm glass spheres, with water, aqueous glycerol solution and silicone oil as liquids, and air as the gas. The voidage at minimum fluidization fell initially to a minimum, then rose gradually with increasing superficial gas velocity, and was lower for three‐phase systems than for corresponding two‐phase (liquid–solid) fluidized beds. The compaction appears to be due to agitation by gas bubbles near the minimum liquid fluidization condition. The gas holdups agree reasonably well with the correlation of Yang et al. (1993). Curves of minimum liquid fluidization velocity, U lmf , vs. superficial gas velocity, U g always show U lmf decreasing as U g increases, initially in a concave‐downward manner, but sometimes concave‐upward.