Volume 93
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Ke, Z., Tian, Y., Li, F., Lu, B., & Wang, W. (2024). Steady-state multiscale CFD simulation of a circulating fluidized bed riser. Particuology, 93, 54-64. https://doi.org/10.1016/j.partic.2024.06.004
Steady-state multiscale CFD simulation of a circulating fluidized bed riser

Zhaojie Ke a b, Yujie Tian a b, Fei Li a b, Bona Lu a b, Wei Wang a b *

a State Key Laboratory of Mesoscience and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China
b School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
10.1016/j.partic.2024.06.004
Pages 54-64, October 2024, Volume 93
Received 22 January 2024, Revised 8 June 2024, Accepted 10 June 2024, Available online 13 June 2024, Version of Record 20 June 2024.
E-mail: wangwei@ipe.ac.cn

Highlights

• Steady-state CFD simulation of a riser is carried out with multiscale modeling.

• The steady-state EMMS drag enables reasonable prediction of axial profiles of voidage.

• Choking transition is predicted for the first time with steady-state CFD simulation.


Abstract

Compared to transient simulation, steady-state simulation of circulating fluidized bed risers is more efficient, but is also harder to perform due to the complex scale-dependency of dense gas-solid flows. In this work, steady-state computational fluid dynamics (CFD) simulation of a riser is performed using the steady energy-minimization multi-scale (EMMS) drag. It is found that the steady state corresponds to an extremely large scale of length and time, thus the grid size required in steady-state simulation is larger than that in transient one. The time-averaged two-fluid model (TFM) coupled with the steady-state EMMS/1M drag model enables a good prediction of the S-shaped, axial solids distribution and the choking transition, whereas the two-phase turbulence and solids stress models are important in predicting the radially core-annular distribution of solids. So far as we know, this is the first time that one can predict the choking transition in a steady-state CFD simulation. Further improvement may need an EMMS modeling of the time-averaged solid stresses.

Graphical abstract
Keywords
Fluidization; Drag force; Steady state; Simulation; Mesoscale