Numerical Simulation of Flow Characteristics of Two-Component Particles in Magnetically Controlled Gas-Solid Bubbling Bed

Numerical
simulation of flow characteristics of two-component particles in magnetically
controlled gas-solid bubbling bed

Biao Wang,
Tianyu Wang, Yurong He ^*

¹ School of Energy Science and
Engineering, Harbin Institute of Technology, 150001, Harbin, China

rong@hit.edu.cn

The gas-solid
fluidized bed under the action magnetic field refers to adding magnetic field
to ordinary gas-solid fluidized bed as the external energy field, and the solid
particles in the flow field are magnetic particles. A magnetic field is added
outside the reactor, and the magnetic field lines pass through the interior of
the bed layer, attracting the particles of magnetic materials to be regularly
distributed in the bed layer. In the fluidization process, the bubbles are
evenly distributed, thus improving the fluidization quality^[1].
The magnetic fluidized bed has outstanding advantages, such as low vibration,
low noise, recyclable use and higher mass and heat transfer rate. It has high
development value and broad application prospect^[2].
It is widely used in many industrial processes, such as filtration, dust
removal, separation of materials, fluidization of viscous particles and
fluidization of particles under microgravity.

So far, domestic
and foreign scholars have conducted some researches on the flow characteristics
of particles in magnetic fluidized beds. For example, in the area of enzymatic
catalysis, Bahar^[3] et
al. fixed the reaction enzyme on magnetic particles and performed the catalytic
reaction in the magnetic fluidized bed. Jovanovic^[4] et
al. conducted experiments and theoretical investigations on the
magnetic-assisted liquid-solid fluidized bed under the normal and microgravity
conditions, and proved that the gradient magnetic field can make the fluidized
bed under microgravity normal fluidization. Wang^[5] et
al. studied the mechanism of flue gas desulfurization in magnetic fluidized
bed, and improved the utilization rate of desulfurizer. Magnetic-fluidized beds
have been applied in the fields of chemical catalysis and material separation
and transportation. However, the practical application of magnetic fluidized
bed is lacking, and most researches are focused on theoretical research.

Fluidized beds
are widely used to separate materials in the fields of industrial production,
metallurgy, chemical industry, cleaning and pharmacy. However, it is
particularly difficult to separate materials by fluidized bed without external
physical fields due to similar particle density and size. Therefore, it is
necessary to study how to improve the separation degree of two-component
particles by adding energy field. Mohanta^[6] et
al. applied the magnetic fluidized bed to the field of coal washing and made
the particle flow more stable in the bed.

In this paper,
MFIX is used as the research tool, and a two-component system composing of
ferromagnetic particles and non-magnetic particles is studied. The discrete
element model is applied to investigate the two-component particles flow
behaviors in a two-dimensional gradient magnetic field with different gradient.
By comparing the simulation results in the bubbling bed with magnetic field and
without magnetic field, it could be found that the ferromagnetic particles
form chains under the action of magnetic field. The separation degree increases
with the increase of magnetic field gradient.

Acknowledgement

This work was financially supported by
the National Natural Science Foundation of China (Grant No. 91534112).

References

[1] Bin Zhang.
Numerical simulation and experimental study of gas-solid two-phase flow in
magnetic fluidized bed [D]. Nanjing: Southeast University, 2004: 1-4.

[2] Ping Zeng,
Tao Zhou, Guanqun Chen, Zhiqiang Ge. Research and
application of magnetic fluidized bed [J]. Chemical progress, 2006, 25(4):
371-373.

[3] Bahar T,
Celebi S S. Performance of immobilized glucoamylase in a magnetically
stabilized fluidized bed reactor (MSFBR)[J]. Enzyme and Microbial Technology,
2000, 26(1): 28-33.

[4] Jovanovic G
N, Sornchamni T, Atwater J E, et al. Magnetically assisted liquid¨Csolid
fluidization in normal and microgravity conditions: experiment and theory[J].
Powder Technology, 2004, 148(2-3): 80-91.

[5] Zhixiao
Wang, Yunfeng Zhang. Study on mechanism of enhanced
flue gas desulfurization by magnetic fluidized bed [J]. Proceedings of the
Chinese Society for Electrical Engineering, 2005, 25(14): 68-52.

[6] Mohanta S,
Rao C S, Daram A B, Chakraborty S, Meikap B C. Air dense medium fluidized bed
for dry beneficiation of coal: technological challenges for future[J].
Particulate Science and Technology, 2013, 31(1): 16-27.