A CFD–DEM study of the behaviour of single-solid and binary mixtures in a pyramidal spouted bed--颗粒学报PARTICUOLOGY

Marchelli, F., Moliner, C., Bosio, B., & Arato, E. (2019). A CFD–DEM study of the behaviour of single-solid and binary mixtures in a pyramidal spouted bed. Particuology, 42, 79-91. https://doi.org/10.1016/j.partic.2018.03.017

A CFD–DEM study of the behaviour of single-solid and binary mixtures in a pyramidal spouted bed

Filippo Marchelli^a *, Cristina Moliner^b, Barbara Bosio ^b, Elisabetta Arato ^b

a Faculty of Science and Technology, Free University of Bozen-Bolzano, Piazza Università 5, 39100 Bolzano, Italy
b Department of Civil, Chemical and Environmental Engineering, University of Genova, Via all’Opera Pia 15, 16145 Genova, Italy

10.1016/j.partic.2018.03.017

Volume 42, February 2019, Pages 79-91

Received 26 October 2017, Revised 2 March 2018, Accepted 26 March 2018, Available online 30 October 2018, Version of Record 21 January 2019.

E-mail: filippo.marchelli@natec.unibz.it

Highlights

• A new CFD–DEM model of a cold-flow spouted bed featuring binary mixtures was developed.

• Segregation phenomena were reproduced through a simplified pseudo-2D geometry.

• Accuracy increased with a complete 3D geometry at the expense of an increase of computational time.

• The Haider and Levenspiel model was suitable for the pseudo-2D geometry.

• The Gidaspow model was suitable for the 3D geometry.

Abstract

We simulated a lab-scale cold-flow spouted bed through computational fluid dynamics (CFD), coupled with the discrete element method (DEM) for the solid phase, using a commercial CFD program, ANSYS FLUENT 18.0. To limit the computational expense, we tested both a simplified pseudo-2D geometry and a complete 3D geometry. We found that the Haider and Levenspiel drag model is suitable for the pseudo-2D geometry; however, this model does not correctly predict fluidisation in the 3D geometry. Conversely, the Gidaspow drag model behaves accurately in the 3D geometry but overestimates the motion of particles in the pseudo-2D geometry. We studied several single-solid and binary mixtures to assess the reproducibility of segregation phenomena. The pseudo-2D model was able to predict the onset and minimum spouting flow rates of all mixtures with good accuracy. An analysis of the volume fraction contours of the binary mixtures permitted us to confirm that segregation phenomena were correctly predicted at low gas velocities. We showed that segregation decreased as the inlet gas flow rate was increased. Calculations performed in the complete 3D geometry were preliminarily assessed as more reliable but required almost four times as much computational time as those for the pseudo 2D geometry.

Graphical abstract

Keywords

Spouted beds; Computational fluid dynamics; Discrete element method; Binary mixtures; Segregation phenomena

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