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Effects of operating conditions on longitudinal solids mixing in a circulating fluidized bed riser
Author(s) -
Rhodes M. J.,
Zhou S.,
Hirama T.,
Cheng H.
Publication year - 1991
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690371003
Subject(s) - residence time distribution , fluidized bed combustion , mixing (physics) , mechanics , tracer , péclet number , flux (metallurgy) , materials science , volume (thermodynamics) , dispersion (optics) , total dissolved solids , fluidized bed , chemistry , thermodynamics , flow (mathematics) , environmental science , environmental engineering , physics , metallurgy , quantum mechanics , nuclear physics , optics
Longitudinal solids mixing was studied experimentally in circulating fluidized bed risers of internal diameter 0.152 m and 0.305 m. Superficial gas velocity and mean solids flux used were 2.8–5.0 m/s and 5.0–80 kg/m 2 ·s, respectively, and the bed solids had a surface volume mean diameter of 71 μm and a particle density of 2,456 kg/m 3 . A sodium chloride tracer was used in impulse injection experiments. A simple, one‐dimensional dispersion model describes measured solids mixing satisfactorily. Peclet numbers ( U o L / D z ) found, in the range 1.0–9.0, were correlated with the riser diameter and mean solids flux. The modeling approach described here permits residence time distribution curves to be calculated directly from the knowledge of superficial gas velocity, mean solids flux, and riser diameter. Longitudinal solids mixing in the riser decreased with increasing riser diameter. The results are consistent with recent hydrodynamic studies.