Hydrodynamic behavior of magnetized fluidized beds with admixtures of Geldart-B magnetizable and nonmagnetizable particles--颗粒学报PARTICUOLOGY

Zhu, Q., Li, H., Zhu, Q., Li, J., & Zou, Z. (2016). Hydrodynamic behavior of magnetized fluidized beds with admixtures of Geldart-B magnetizable and nonmagnetizable particles. Particuology, 29, 86-94. https://doi.org/10.1016/j.partic.2015.12.010

Hydrodynamic behavior of magnetized fluidized beds with admixtures of Geldart-B magnetizable and nonmagnetizable particles

Quanhong Zhu ^{a b}, Hongzhong Li ^a *, Qingshan Zhu ^a^*, Jun Li ^a, Zheng Zou ^a

a State Key Laboratory of Multi-phase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, P.O. Box 353, Beijing 100190, China
b University of Chinese Academy of Sciences, Beijing 100049, China

10.1016/j.partic.2015.12.010

Volume 29, December 2016, Pages 86-94

Received 29 July 2015, Revised 6 December 2015, Accepted 17 December 2015, Available online 17 April 2016, Version of Record 18 November 2016.

E-mail: hzli@ipe.ac.cn; qszhu@ipe.ac.cn

Highlights

• Four distinct flow regimes exist in MFBs operated under magnetization-LAST mode.

• High magnetic field intensity induced segregation of binary mixture in MFBs.

• Fluidization quality could be improved by magnetic field only before segregation occurred.

• The magnetically stabilized bed flow regime could not be achieved under magnetization-LAST mode.

Abstract

This work focuses on the hydrodynamic behavior of admixtures of Geldart-B magnetizable and nonmagnetizable particles in a magnetized fluidized bed. The applied magnetic field was axial, uniform, and steady. In operating the beds, the magnetization-LAST mode was adopted under which four distinct flow regimes exist: fixed, magnetized-bubbling, partial segregation-bubbling, and total segregation-bubbling. The operational phase diagram was drawn to display the transitions between flow regimes in an intuitive manner. Only in the magnetized-bubbling regime could the magnetic field reduce the bubble size and improve fluidization quality. In the segregation-bubbling regimes, fluidization quality deteriorated as segregation developed. The segregation of the binary mixture was quantitatively studied by observing pressure drops in the local bed. Reasons for the improvement in fluidization quality as well as the occurrence of segregation were analyzed. Furthermore, the flow regime transition under magnetization-LAST operation mode was different from that under magnetization-FIRST mode. The magnetically stabilized bed (MSB) flow regime, which could be easily created under magnetization-FIRST mode, could no longer be achieved under magnetization-LAST mode. With the admixture, the MSB was proved to be a metastable equilibrium state. Under the magnetization-LAST mode, the admixture bed reached directly the stable equilibrium state—bubbling with segregation.

Graphical abstract

Keywords

Magnetized fluidized bed; Admixture; Magnetization-LAST; Flow regime; Hydrodynamic; Segregation

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