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Position and velocity of a large particle in a gas/solid riser using the radioactive particle tracking technique
Author(s) -
Godfroy Larin,
Chaouki Jamal,
Larachi Faïçal
Publication year - 1999
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.5450770210
Subject(s) - particle (ecology) , mechanics , turbulence , fluidized bed combustion , particle velocity , dispersion (optics) , position (finance) , circulation (fluid dynamics) , materials science , volumetric flow rate , chemistry , fluidized bed , thermodynamics , physics , optics , geology , oceanography , finance , economics
The flow behavior of the solids phase in the fully developed region of a laboratory‐scale circulating fluidized bed riser was studied using an assembly of sixteen NaI detectors to determine the position of a 500 μm radioactive particle, 100 times/s. The particle location was inferred from the number of γ‐rays recorded by the assembly. The knowledge of the instantaneous positions enabled the determination of the instantaneous and mean velocity fields. Tests were conducted in a 0.082 m diameter, 7 m tall riser using 150 μm silica sand particles. Data were obtained at a gas superficial velocity of 4 m/s and solids mass fluxes from 23 to 75 kg/m 2 ·s. Radial profiles of axial particle velocity showed that the solids velocity decreased with increasing solids circulation rates. Correspondingly, turbulent particle velocities and solids dispersion coefficient in the longitudinal direction were found to decrease as the solids circulation rate increased. The cross‐sectional area where, on average, solids downflow took place, increased with increasing solids circulation rate.