Modeling the hydrodynamics of cocurrent gas–solid downers according to energy-minimization multi-scale theory--颗粒学报PARTICUOLOGY

Zhang, Z., Hu, S., Liu, X., & Zhao, H. (2016). Modeling the hydrodynamics of cocurrent gas–solid downers according to energy-minimization multi-scale theory. Particuology, 29, 110-119. https://doi.org/10.1016/j.partic.2016.01.011

Modeling the hydrodynamics of cocurrent gas–solid downers according to energy-minimization multi-scale theory

Zhixin Zhang ^{a b}, Shanwei Hu ^a, Xinhua Liu ^a *, Hui Zhao ^b

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

10.1016/j.partic.2016.01.011

Volume 29, December 2016, Pages 110-119

Received 3 April 2015, Revised 8 November 2015, Accepted 2 January 2016, Available online 13 May 2016, Version of Record 18 November 2016.

E-mail: xhliu@ipe.ac.cn

Highlights

• The EMMS theory was adopted to model concurrent downward gas–solid flow.

• Multiscale interphase interactions were explicitly considered in the model formulation.

• A unified stability condition was proposed for concurrent downward gas–solid flow.

• The model was solved without introducing cluster-specific empirical correlations.

Abstract

Cocurrent gas–solid downer reactors have many applications in industry because they possess the technological advantages of a lower pressure drop, shorter residence time, and less solid backmixing when compared with traditional circulating fluidized bed risers. By introducing the concept of particle clusters explicitly, a one-dimensional model with consideration of the interphase interactions between the fluid and particles at both microscale and mesoscale is formulated for concurrent downward gas–solid flow according to energy-minimization multi-scale (EMMS) theory. A unified stability condition is proposed for the differently developed sections of gas–solid flow according to the principle of the compromise in competition between dominant mechanisms. By optimizing the number density of particle clusters with respect to the stability condition, the formulated model can be numerically solved without introducing cluster-specific empirical correlations. The EMMS-based model predicts well the axial hydrodynamics of cocurrent gas–solid downers and is expected to have a wider range of applications than the existing cluster-based models.

Graphical abstract

Keywords

Mathematical modeling; Hydrodynamics; Fluidization; Downer; Cluster; Multiscale

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