Evaluation of the effect of wall boundary conditions on numerical simulations of circulating fluidized beds--颗粒学报PARTICUOLOGY

Kong, L., Zhang, C., & Zhu, J. (2014). Evaluation of the effect of wall boundary conditions on numerical simulations of circulating fluidized beds. Particuology, 13, 114–123. https://doi.org/10.1016/j.partic.2013.04.007

Lei Kong ^a, Chao Zhang ^a *, Jesse Zhu ^b

a Department of Mechanical and Materials Engineering, The University of Western Ontario, London, Ontario, N6A 5B9, Canada
b Department of Chemical and Biochemical Engineering, The University of Western Ontario, London, Ontario, N6A 5B9, Canada

10.1016/j.partic.2013.04.007

Volume 13, April 2014, Pages 114-123

Received 24 August 2012, Revised 31 March 2013, Accepted 12 April 2013, Available online 8 July 2013.

E-mail: czhang@eng.uwo.ca

Highlights

• A 2D circulating fluidized bed riser system is modeled.

• The specularity coefficient has a strong effect on the solid particle distribution near the wall.

• The particle–wall restitution coefficient has less effect on solid particle distribution near the wall than that of specularity coefficient.

• The specularity and particle–wall restitution coefficients affect the lateral velocity of the solid particles near the wall.

Abstract

A computational fluid dynamics (CFD) modeling of the gas–solids two-phase flow in a circulating fluidized bed (CFB) riser is carried out. The Eularian–Eularian method with the kinetic theory of granular flow is used to solve the gas–solids two-phase flow in the CFB riser. The wall boundary condition of the riser is defined based on the Johnson and Jackson wall boundary theory (Johnson & Jackson, 1987) with specularity coefficient and particle–wall restitution coefficient. The numerical results show that these two coefficients in the wall boundary condition play a major role in the predicted solids lateral velocity, which affects the solid particle distribution in the CFB riser. And the effect of each of the two coefficients on the solids distribution also depends on the other one. The generality of the CFD model is further validated under different operating conditions of the CFB riser.

Graphical abstract

Keywords

CFD; Circulating fluidized bed; Gas–solids two-phase flow; Wall boundary condition; Specularity coefficient; Particle–wall restitution coefficient

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