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Packed bed reactors are widely used in the chemical and process
industry amongst others for highly exothermic or endothermic catalytic
surface reactions. Such reactors are characterized by a small
tube to particle diameter ratio D/d to ensure a safe thermal management.
For the design of such apparatuses the well-known correlations
for packed bed reactors cannot be used, because these reactors
are dominated by the influence of the confining wall, which affects
the porosity and the velocity field and as a result also the species
and temperature distribution within the bed.
For spatially resolved simulations of packed bed reactors a randomly
packed bed has to be generated and meshed. Special attention
has to be paid on the mesh at the particle-particle and particlewall
contact points. We developed a method, which flattens the
particles locally in the vicinity of the contact points and we could
show, that this method does not affect significantly the bed properties
and the fluid dynamics in terms of bed porosity, radial porosity
distribution and pressure drop.
Based on this published work we developed a workflow and a tool
which allows an automated simulation: generation of a packed bed
with DEM (discrete element method), meshing and solving the
transport equations with a finite volume code. The whole workflow
is done within the software package STAR-CCM+ by CD-adapco.
The simulation time could be reduced significantly and depends on
the number of particles (typically 1-2 days for 1500 particles).
Further we used the built-in DEM capability to generate random
packings of non-spherical particles like cylinders and Raschig rings,
which are more often used in the chemical industry, as a composition
of spherical particles. For the meshing and the CFD calculation
these approximated shapes are replaced by their original exact
With the described workflow we have investigated spherical as well
as non-spherical packings with D/d between 2 and 10 and packing
heights between 10d and 40d. The results are validated in terms of
bed porosity, radial porosity and velocity distribution and temperature
profiles with experimental results from literature.
Based on these results the interplay between the flow field, the
temperature, the species distribution and the chemical reaction in
packed bed reactors can be investigated in detail.
Keywords: DEM, packed beds, chemical reactors, process industry,
CFD, hydrodynamics .

Author Name: 
Ravindra AGLAVE
Author Company: 
Conference Location: 
Trondheim, NORWAY
Conference Proceeding PDF: 
Conference Date: 
Tuesday, June 17, 2014
Conference Name: 
International Conference on CFD in Oil & Gas, Metallurgical and Process Industries