(55e) DEM Simulations of Fluidized Bed Using a Scaled Particle Approach

Fluidized beds are widely used in chemical process and
refining industry due to various advantages they offer over fixed bed reactors.
Nonetheless, their design is a difficult task and modeling is increasingly
deployed to understand and scale-up these equipment. This
paper reports the results for large-scale parallel simulations of fluidized bed
using Discrete Element Method (DEM) fully coupled with fluid flow model using
STAR-CCM+ software developed by CD-adapco. The
simulation model uses the geometry and set-up as described in reference [1] and
the simulation results are being compared with corresponding experimental
results from the same reference.  In the
numerical model, the particle's drag depends on local solid fraction with Ergun
equation based drag used for dense regions and Wen-Yu drag model otherwise. A
novel approach of scaling up the DEM particle's size with simultaneous scaling
of drag coefficient is introduced and used. For each particle size scaling
factor the drag scaling factor is obtained through parametric study by
reproducing the fluidization conditions obtained in experiment. The scaling of
drag law as a function of particle size scaling is discussed as well as the
effect of scaling approach on simulation time and accuracy of numerical
model.  Authors believe that this
approach will be able to achieve a right balance between accuracy (a feature of
DEM methods) and speed (a feature of computation particle approaches) to enable
practical design and scale-up workflow.