A novel measurement method for the mixing of binary mixtures in
three-dimensional fluidized beds
A novel measurement system for mixing property of binary mixtures in
three-dimensional fluidized beds is developed based on capacitance probe
method. The mixing processes at multi-positions of the bed are acquired
simultaneously. A new dispersion coefficient is proposed to characterize
the local dispersion of particles and a new mixing index is proposed to
evaluate the local mixing quality in three-dimensional fluidized beds.
The effect of convection and diffusion mechanism on particle mixing is
discussed separately. Results show that the governing mechanism of
particle mixing at the center and top of the beds is convection;
meanwhile the governing mechanism for particle mixing at the bottom and
near the wall is diffusion. The radial dispersion coefficient at the
half-radius of the bed is mainly between 0.0038 and 0.026 m2/s, which is
about 1.5 times that near the wall. The vertical dispersion coefficient
is about 2.5 times that the radial dispersion coefficient.