Modeling the axial hydrodynamics of gas–solid counter-current downers--颗粒学报PARTICUOLOGY

Liu, J., Liu, X., Zhang, Z., Zhao, H., & Ge, W. (2020). Modeling the axial hydrodynamics of gas–solid counter-current downers. Particuology, 50, 135-143. https://doi.org/10.1016/j.partic.2019.08.001

Modeling the axial hydrodynamics of gas–solid counter-current downers

Juanbo Liu ^{a b}, Xinhua Liu ^a *, Zhixin Zhang ^a, Hui Zhao ^c, Wei Ge ^{a b *}

a State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
b School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100490, China
c State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Qingdao 266555, China

10.1016/j.partic.2019.08.001

Volume 50, June 2020, Pages 135-143

Received 23 October 2018, Revised 11 May 2019, Accepted 19 August 2019, Available online 5 October 2019, Version of Record 7 April 2020.

E-mail: xhliu@ipe.ac.cn; wge@ipe.ac.cn

Highlights

• EMMS theory is used to simulate gas–solid counter-current downward flow.

• The model predicts well the axial hydrodynamics of counter-current downers.

• An inflexional voidage variation with gas velocity is computed in the downers.

• The predictions are supported by a CFD–DEM simulation.

• The flooding behavior is quantified further according to the model predictions.

Abstract

Gas–solid counter-current downer reactors, in which particles move downward in an upward gas flow, can achieve high solid concentration for high heat and/or mass transfer rates. However, the particles may reverse their direction or even be carried out of the reactor as the gas flow rate increases. This is closely related to “flooding” in counter-current flows. The energy minimization multiscale (EMMS) model well describes multiscale heterogeneity in gas–solid cocurrent upward flows. It is further developed to simulate gas–solid counter-current downward flows because similar heterogeneity can also be found in downers. The model characterizes well the axial hydrodynamics and predicts an inflexional voidage variation with superficial gas velocity in the fully developed region. This is supported by a simulation based on computational fluid dynamics and the discrete element method. The flooding predicted by the model agrees better with experiment than previous models.

Graphical abstract

Keywords

Mathematical modeling; Counter-current downer; Flooding; EMMS; Mesoscale

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