(265b) Numerical Hydrodynamics Study of Gas Solid Vortex Reactor for Process Intensification in Fluidization Technology

Niyogi, K. - Presenter, Ghent University
Pantzali, M. N. - Presenter, Ghent University
Heynderickx, G. J. - Presenter, Ghent University
Marin, G. B. - Presenter, Ghent University

Gas Solid Vortex Reactor (GSVR) is a novel type of reactor, which surpasses major
limitations of conventional gravitational Fluidized Bed (FB) reactors by replacing
the gravitational field with a centrifugal field1, 2. In the
GSVR, the process gas flows through tangentially inlet slots positioned along
the circumferential wall of a static cylindrical chamber. The gas is forced to
leave the chamber via the centrally placed exhaust. The solid particles, which
are fed into the chamber via a solids inlet, are entrained by the gas and set
to rotation. When the centrifugal force exerted on the rotating particles
outweighs the drag force exerted by the flowing gas, a rotating solids bed is
formed near the circumferential wall of the GSVR (Fig. 1). Since the
centrifugal force can exceed gravitational force significantly, high
gas-solid sli
p velocities are developed. Hence, the GSVR can achieve higher
heat and mass transfer as compared to conventional FB, leading to Process Intensification
(PI)3. Moreover, the GSVR differs from Rotating Fluidized Bed
reactors (RFB), as it enables centrifugal fluidization in a static
geometry, thus minimizing mechanical abrasion caused by moving parts. Among the
several possible applications of the GSVR, drying of biomass4, effluent
SO2/NOx adsorption5, even nuclear rocket fuel
propulsion6 have been investigated in literature.   

In the Laboratory for
Chemical Technology, an experimental semi-batch GSVR setup has been constructed
and tested under various operational conditions7-9. However, the
need for non-intrusive measurement techniques8, has limited the
information that the experiments alone can provide. This necessitates the use
of Computational Fluid Dynamics (CFD) simulation of the hydrodynamics inside
the GSVR.

 In the present work,
the commercial CFD software, FLUENT® 14.0 is used to numerically
study the detailed three-dimensional (3D) cold flow hydrodynamics in the GSVR. Transient
CFD calculations are performed on 1/9th section of the whole geometry
to reduce computational cost. The multiphase flow is simulated in an Eulerian-Eulerian
framework, where the two phases, air and polymer particles, are treated as
interpenetrating continua. Kinetic Theory of Granular Flow (KTGF) modeling is
used to close the solid phase equations. As the GSVR can give rise to the formation
of dense beds, separate turbulence modeling is considered per phase, to account
for four-way coupling of phase momentum equations. Since the main interest is
focused on extracting global fluidization behavior inside the GSVR, only time-averaged
data are considered.

First, a detailed sensitivity
study is carried out to identify the key numerical parameters influencing the
simulation results. The simulation data is found to be highly sensitive to the
values of the particle-particle restitution coefficient and the particle-wall
specularity coefficient. Particle-particle friction modeling is also found to
become important at higher solids capacity, for accurate prediction of maximum
solids content that the GSVR can hold at a given gas flow rate. Optimal
parameter values have been determined by comparing the simulation data with
their experimental counterpart9 over a wide range of operating
conditions (gas flow rate, solids capacity) and particle properties (density,
size). The validated model is then used to investigate channeling, slugging
inside the GSVR. This helps identify the full range of operability of the
reactor. Next the degree of fluidization is investigated. The solids are found
to exhibit a complex pattern of bed behavior, ranging from almost packed to
fluidized regime. The simulation results are used to construct a fluidization
regime map for the GSVR (Fig. 2). This fluidization regime map can be applied to
compare the GSVR performance with the traditional FB and RFB
technologies and assess the extent of PI achieved in the GSVR.


The computational work
was carried out using the STEVIN Supercomputer Infrastructure at Ghent
University, funded by Ghent University, the Flemish Supercomputer Center (VSC),
the Hercules Foundation and the Flemish Government ? department EWI. The
authors acknowledge the financial support from the European Research Council
under the European Union's Seventh Framework Programme FP7/2007-2013/ERC grant
agreement n° 290793.


1.       Ekatpure RP,
Suryawanshi VU, Heynderickx GJ, de Broqueville A, Marin GB. Experimental
investigation of a gas?solid rotating bed reactor with static geometry. Chem.
Eng. Process. Process Intensif. 2011;50(1):77-84.

2.       De Wilde J, de
Broqueville A. Experimental investigation of a rotating fluidized bed in a
static geometry. Powder Technol. 2008;183(3):426-435.

3.       Ashcraft RW,
Heynderickx GJ, Marin GB. Modeling fast biomass pyrolysis in a gas?solid vortex
reactor. Chem. Eng. J. 2012;207?208(0):195-208.

4.       Volchkov EP,
Dvornikov NA, Yadykin AN. Characteristic features of heat and mass transfer in
a fluidized bed in a vortex chamber. Heat Transf. Res. 2003;34:486-498.

5.       R.W. Ashcraft,
J. Kovacevic, G.J. Heynderickx, G.B. Marin. Assessment of a gas?solid vortex
reactor for SO2/NOx adsorption from flue gas. Ind. Eng. Chem. Res. 52 (2013)

6.       Lewellen W.S.,
Stickler D.B. Two-Phase Vortex Investigation Related to the Colloidal Core
Nuclear Reactor. ARL TR 72-0037, Aerospace Research Laboratory, Wright
Patterson Air Force Base, OH, USA, (1972).

7.       Dutta A,
Ekatpure RP, Heynderickx GJ, de Broqueville A, Marin GB. Rotating fluidized bed
with a static geometry: Guidelines for design and operating conditions. Chem.Eng.Sci.

8.       Kovacevic JZ,
Pantzali MN, Heynderickx GJ, Marin GB. Bed stability and maximum solids
capacity in a Gas?Solid Vortex Reactor: Experimental study. Chem.Eng.Sci.

JZ, Pantzali MN, Niyogi K, Deen NG, Heynderickx GJ, Marin GB. Solids velocity
fields in a cold-flow Gas?Solid Vortex Reactor. Chem.Eng.Sci. 2015;123:220-230.

Fig. 1. A schematic representation of the Gas-Solid
Vortex Reactor

2. Field  of solids volume fraction in an azimuthal GSVR plane. Fluidization
regimes with increasing solids capacity