(215a) SemiEmpirical Drag Correlation for a Gas Solid Vortex Reactor Starting from the Radial Momentum Balances
 Conference: AIChE Annual Meeting
 Year: 2016
 Proceeding: 2016 AIChE Annual Meeting
 Group: Particle Technology Forum
 Session:
 Time:
Monday, November 14, 2016  3:15pm3:32pm
Practical
Information
All fields are compulsory
Last name 
Friedle 
First name 
Maximilian 
Email address 

Keywords (3) 
Fluidization, Particle Technology 
Abstract title 
Semiempirical drag correlation for a Gas Solid Vortex Reactor starting from the radial momentum balances 
Authors 
Friedle, M; Niyogi, K; Torregrosa Galindo, M.M.; Heynderickx, G.J., Marin, G.B. 
Preferred presentation method 
Oral presentation 
Division/Forum 
Particle Technology Forum 
Session 
03B06 Fundamentals of Fluidization I 
Semiempirical drag correlation
for a Gas Solid Vortex Reactor starting from the radial momentum balances
Friedle,
M; Niyogi, K; Torregrosa Galindo, M.M.; Heynderickx^{*}, G.J., Marin,
G.B.
Laboratory for Chemical
Technology, Department of Chemical Engineering, Ghent University,
Technologiepark 914, B9052 Gent, Belgium
^{*}Corresponding author:
Geraldine.Heynderickx@UGent.be
The Gas Solid Vortex Reactor
(GSVR) is a novel rotating fluidized bed reactor with a stationary geometry, in
which the gravitational force in conventional fluidized bed is replaced by a
centrifugal force resulting in process intensification^{1}.
In a GSVR a stable solids bed can be obtained for high gas flow rates thereby
increasing the slip velocity between the phases. Consequently, the overall heat
and mass transfer increases as to compared to a gravitational fluidized bed^{2, 3}. The GSVR is a disclike chamber where the process gas is introduced
through a series of azimuthally inclined injection slots, uniformly distributed
along the circumferential chamber wall. Inside the chamber the gas swirls
towards the unidirectional central gas exhaust. When particles are fed inside
this swirling flow field the gas transfers part of its momentum to the
particles. The particles start to rotate in the chamber and form a stable,
dense, rotating bed at the circumferential wall (Fig. 1). The rotational motion
generates a radially outward directed centrifugal force on the particles. The
injected gas flowing through the solid bed towards the unidirectional central gas
exhaust generates a counteracting radially inward directed drag force on the
particles. The GSVR compiles a unique set of characteristics typical for reactor
technologies that combine high gassolid slip velocities, good particle mixing
and continuous operation under dense bed conditions^{4}.
As such, the GSVR technology has already been considered for different
applications, like drying of biomass^{5},
biomass pyrolysis^{1}, SO_{2}NO_{x} adsorption from
flue gases^{6} or nuclear rocket fuel propulsion^{7}.
As no universal understanding of
the indepth hydrodynamics of the GSVR technology is readily available, scaling
and design of industriallysized GSVRs are difficult uptodate. An indepth
understanding of a technology often comes from a first principles approach. A first
step in understanding of the multiphase hydrodynamics in the GSVR based on the
radial momentum balances is aimed at in the present study.
An extensive set of experimental
data has been collected by different researchers^{2,
3, 8, 9} over the past years in an experimental semibatch GSVR setup at
the Laboratory for Chemical Technology. The investigated range of operations
spans a wide range of gas flow rates, particle sizes, particle densities and
bed masses. The experimental data is used to verify the assumptions made and to
determine the model parameters of the semiempirical drag formulation.
Following some simplifying
assumptions, like neglecting the weight of the gas, the wall force and
particleparticle interaction, the radial solids and gas momentum balances are
combined to:
(1) 
The resulting onedimensional,
averaged equation shows that the pressure drop over the bed height balances the
centrifugal force of the bed. Here describes the
radial height of the bed, the overall
volume of the bed, the mass of the
bed and the outer
radius of the unit. The azimuthal solids velocity is averaged
over the height of the bed.
Pressure drop over a conventional
fluidized bed is usually estimated using semiempirical correlations for the
drag force^{10,
11}. In the present work a semiempirical correlation for the radial drag
force on the GSVR bed is developed, starting from the wellknown correlations
for singleparticle drag^{12}.
The resulting correlation is:

(2) 
Here is the void
fraction, the particle
diameter, is the gas
density and the radial
superficial gas velocity in the unit. Equations 1 and 2 are combined and
written in dimensionless form :

(3) 
The correlation parameters are
obtained through linear regression of the available experimental data sets. The
parity plot for equation 3 is shown in Figure 3. The radial Reynolds number and
the centrifugal Archimedes number are calculated from equations 4 and 5, where is the gas
viscosity.
(4) 

(5) 
Using this modeling approach a more
fundamental understanding of the interaction between gas and particles in a
dense rotating bed is obtained. The absence of the void fraction as a classic
modeling parameter, states that the gas interacts with every particle in the
same way and that particleparticle interaction is minimal. In this respect the
GSVR differs from conventional fluidization technologies operating in the dense
bed regime, confirming the appropriateness of the GSVR for innovative industrial
applications.
Acknowledgments
This
work was supported by the European Research Council under the European
Union’s Seventh Framework Program (FP7/20072013) / ERC grant agreement n°
290793.
References
1. Ashcraft RW, Heynderickx GJ, Marin GB, 2012. Modeling fast biomass
pyrolysis in a gassolid vortex reactor. Chemical Engineering Journal 207,
195208.
2. Ekatpure
RP, Suryawanshi VU, Heynderickx GJ, de Broqueville A, Marin GB, 2011.
Experimental investigation of a gas–solid rotating bed reactor with static
geometry. Chemical Engineering and Processing: Process Intensification 50,
7784.
3. Kovacevic
JZ, Pantzali MN, Heynderickx GJ, Marin GB, 2014. Bed stability and maximum
solids capacity in a GasSolid Vortex Reactor: Experimental study. Chemical
Engineering Science 106, 293303.
4. De
Wilde J, 2014. Gas–solid fluidized beds in vortex chambers. Chemical
Engineering and Processing: Process Intensification 85, 25690.
5. Eliaers
P, De Wilde J, 2013. Drying of Biomass Particles: Experimental Study and
Comparison of the Performance of a Conventional Fluidized Bed and a Rotating
Fluidized Bed in a Static Geometry. Drying Technology 31, 23645.
6. Ashcraft
RW, Kovacevic J, Heynderickx GJ, Marin GB, 2013. Assessment of a GasSolid
Vortex Reactor for SO2/NOx Adsorption from Flue Gas. Ind Eng Chem Res 52,
86175.
7. Lewellen
W. A study of fluid dynamics of gaseous nuclear rocketsQuarterly Progress
Report, July 1September 30, 1968. Massachusetts Inst. of Tech., Cambridge,
1968.
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MN, Kovacevic JZ, Heynderickx GJ, Marin GB, 2015. Radial Pressure
Proﬁles in a ColdFlow GasSolid Vortex Reactor. AIChE Journal 61,
411425.
9. Kovacevic
JZ, Pantzali MN, Niyogi K, Deen NG, Heynderickx GJ, Marin GB, 2015. Solids velocity
fields in a coldflow Gas–Solid Vortex Reactor. Chemical Engineering Science
123, 22030.
10. Gibilaro
LG, Di Felice R, Waldram SP, Foscolo PU, 1985. Generalized friction factor and
drag coefficient correlations for fluidparticle interactions. Chemical
Engineering Science 40, 181723.
11. Ergun
S, 1952. Fluid flow through packed columns. Chem Eng Prog 48, 8994.
12. Gidaspow D, 1994. Multiphase Flow and
Fluidization. Academic Press, Boston.
Fig.
1. A schematic representation of the GasSolid Vortex Reactor^{2}
Fig.
2. Plot for the centrifugal force of the bed and the force exerted by the
pressure on the bed (Equation 1).
Fig.
3. Parity plot for the semiempirical correlation for the particlegas
interaction in the GSVR (Equation 3).