Particle-scale and sub-grid drag models coupled CFD for simulating the CO methanation in a CFB riser--颗粒学报PARTICUOLOGY

Li, J., Jia, Y., Ouyang, B., Yang, B., Luo, Z.-H., & Liu, Z.-W. (2023). Particle-scale and sub-grid drag models coupled CFD for simulating the CO methanation in a CFB riser. Particuology, 83, 178-193. https://doi.org/10.1016/j.partic.2023.02.014

Particle-scale and sub-grid drag models coupled CFD for simulating the CO methanation in a CFB riser

Jiageng Li ^a, Yong Jia ^a, Bo Ouyang ^b, Bolun Yang ^c, Zheng-Hong Luo ^b *, Zhong-Wen Liu ^a *

a Key Laboratory of Syngas Conversion of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi'an, 710119, China
b Department of Chemical Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240, China
c School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an, 710049, China

10.1016/j.partic.2023.02.014

Volume 83, December 2023, Pages 178-193

Received 20 December 2022, Revised 14 February 2023, Accepted 14 February 2023, Available online 7 March 2023, Version of Record 20 March 2023.

E-mail: luozh@sjtu.edu.cn; zwliu@snnu.edu.cn

Highlights

• Particle-scale model reveals the transient diffusion and reactions inside the catalysts.

• Sub-grid drag model considers the effects of the meso-scale and chemical reactions.

• Strategy for coupling the particle-scale and sub-grid drag models into CFD is proposed.

• The coupled model can predict accurate gas-solid flow and chemical reactions in a riser.

• The coupled model allows coarse grid and large time step size to accelerate the simulations.

Abstract

The diffusion and chemical reactions inside the catalyst particles and the heterogeneous flow structure in the computational cells are key factors to affect the accuracy of the coarse-grid simulation in circulating fluidized bed (CFB) methanation reactors. In this work, a particle-scale model is developed to calculate the effective reaction rate considering the transient diffusion and chemical reactions in the particle scale, i.e., the scale of the single catalyst particle. A modified sub-grid drag model is proposed to consider the effects of the meso-scale and chemical reactions on the heterogeneous gas-solid interaction, where the meso-scale is between the single particle and the whole reactor and featured with the particle cluster. Subsequently, a coupled model is developed by integrating the particle-scale and modified sub-grid drag models into CFD. Moreover, the coupled model is validated to achieve accurate predictions on the CO methanation process in a CFB riser. Notably, the coupled model can be performed with a coarse grid (∼58 times particle diameter) and a large time step (0.005 s) to accelerate the simulation. By simply changing the reaction kinetics, different gas-solid catalytic reaction systems can be simulated by using the coupled model.

Graphical abstract

Keywords

Computational fluid dynamics; Circulating fluidized bed; CO methanation; Particle-scale model; Drag model

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