Title of article :
Solids mixing behavior in a nano-agglomerate fluidized bed
Author/Authors :
Huang، نويسنده , , Run-Cang and Wang، نويسنده , , Yao and Wei، نويسنده , , Fei، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2008
Pages :
8
From page :
334
To page :
341
Abstract :
The nano-particles mixing behavior in a nano-agglomerate fluidized bed (NAFB) using R972, a kind of nano-SiO2 powder, was investigated by the nano-particle coated phosphors tracer method. The axial and radial solids dispersion coefficients in this system were two orders of magnitude lower than those in fluid catalytic cracking (FCC) catalyst systems. The axial solids dispersion coefficient increased with increasing superficial gas velocities, and ranged between 9.1 × 10− 4 and 2.6 × 10− 3 m2/s. There was a step increase in the axial solids dispersion coefficient between the particulate fluidization regime and bubbling and turbulent fluidization regimes. As the superficial gas velocity increased, the radial solids dispersion coefficient increased gradually, from 1.2 × 10− 4 to 4.5 × 10− 4 m2/s. The much smaller Da and Dr, compared to regular fluidized systems, is mainly due to the reduced density difference between the fluidized particles and fluidizing medium. To validate this, the solids dispersion coefficients in the NABF were compared with literature values for liquid–solid particulate systems in the particulate fluidization regime and FCC systems in the bubbling and turbulent fluidization regimes. The density difference between the fluidized particles and fluidizing medium and kinetic viscosity of the fluidizing medium, and other hydrodynamic factors like the superficial velocity of the fluidizing medium and the average diameters of the fluidized particles, were the key factors in the solids mixing in the fluidized beds. Empirical correlations are given to describe the results.
Keywords :
Nano-agglomerate fluidized bed (NAFB) , Solids mixing , Multi-stage agglomerate (MSA) , Fluidization
Journal title :
Powder Technology
Serial Year :
2008
Journal title :
Powder Technology
Record number :
1697425
Link To Document :
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