Flow structures inside a large-scale turbulent fluidized bed of FCC particles: Eulerian simulation with an EMMS-based sub-grid scale model--颗粒学报PARTICUOLOGY

Wang, J. (2010). Flow structures inside a large-scale turbulent fluidized bed of FCC particles: Eulerian simulation with an EMMS-based sub-grid scale model. Particuology, 8(2), 176-185. https://doi.org/10.1016/j.partic.2009.03.013

Flow structures inside a large-scale turbulent fluidized bed of FCC particles: Eulerian simulation with an EMMS-based sub-grid scale model

Junwu Wang^*

State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Science, P.O. Box 353, Beijing 100190, China

10.1016/j.partic.2009.03.013

Volume 8, Issue 2, April 2010, Pages 176-185

Received 13 January 2009, Accepted 24 March 2009, Available online 2 February 2010.

E-mail: J.Wang@tnw.utwente.nl

Highlights

Abstract

Turbulent fluidized bed reactors are widely used in industry. However, CFD simulations of the hydrodynamic characteristics of these reactors are relatively sparse, despite the urgent demand from industry. To address this problem, Eulerian simulations with an EMMS-based sub-grid scale model, accounting for the effect of sub-grid scale structures on the inter-phase friction, are performed to study the hydrodynamics inside a large-scale turbulent fluidized bed of FCC particles. It is shown that the simulated axial and radial solid concentration profiles, entrained solid fluxes and standard deviation of the solid concentration fluctuation agreed well with experimental data available in the literature. In-depth analysis of time-averaged particle velocity and solid concentration shows that a dense-suspension upflow regime coexists with fast fluidization regime in this bed, which is reminiscent of the hydrodynamic characteristics in high-density circulating fluidized bed (CFB) risers, even though they are operated in different fluidization regimes. The Reynolds stresses in turbulent fluidized beds are anisotropic, but the degree of anisotropy is far less pronounced than the reported values in CFB risers. It was also found that the solid concentration fluctuation and axial particle velocity fluctuation are strongly correlated.

Graphical abstract

Keywords

Fluidization; Eulerian simulation; EMMS model; Sub-grid scale model

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