Effect of wall boundary condition on CFD simulation of CFB risers

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• 作者：Xinyu Zhou ; Jinsen Gao ; Chunming Xu ; Xingying Lan
• 关键词：Circulating fluidized bed ; Boundary condition ; EMMS ; CFD ; Specularity coefficient ; Particle-wall restitution coefficient
• 刊名：Particuology
• 出版年：2013
• 出版时间：October, 2013
• 年：2013
• 卷：11
• 期：5
• 页码：556-565
• 全文大小：2338 K

文摘

The effect of solid-phase wall boundary condition on the numerical simulation of gas-solid flow in CFB risers containing FCC particles was investigated using the two-fluid model incorporating the kinetic theory of granular flow. Both the Gidaspow drag model and the EMMS-based drag model were used. The wall boundary condition was applied to describe the interaction between particles and wall. Based on the experimental system of , parametric studies of specularity coefficient (¦Õ = 1.0, 0.6, 0.0005, 0.00005, 0) and particle-wall restitution coefficient (e_w = 0.6, 0.9, 0.95, 0.99, 0.999) were performed to evaluate their effects on axial voidage profile, solids flux, meso-scale and heterogeneous structures. Simulation results showed that solid-phase wall boundary condition had little effect on axial voidage profile when the Gidaspow drag model was used. However, the specularity coefficient ¦Õ had a pronounced influence on flow behavior when the EMMS-based drag model was used, and a small specularity coefficient (¦Õ = 0.00005, 0) could result in better agreement with experimental data. The particle-wall restitution coefficient e_w plays but a minor role in the holistic flow characteristics.