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Open AccessFeature PaperArticle

Computational Fluid Dynamics Simulation of Gas–Solid Hydrodynamics in a Bubbling Fluidized-Bed Reactor: Effects of Air Distributor, Viscous and Drag Models

1
Department of Chemical and Environmental Engineering, Faculty of Engineering, Universiti Putra Malaysia, Serdang 43400, Malaysia
2
Sustainable Process Engineering Research Center, Faculty of Engineering, Universiti Putra Malaysia, Serdang 43400, Malaysia
3
Department of Chemical Engineering, Brunel University London, Uxbridge UB8 3PH, UK
4
Division of Sustainable Development, College of Science and Engineering, Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha 34110, Qatar
*
Authors to whom correspondence should be addressed.
Processes 2019, 7(8), 524; https://doi.org/10.3390/pr7080524
Received: 8 July 2019 / Revised: 26 July 2019 / Accepted: 7 August 2019 / Published: 8 August 2019
PDF [4311 KB, uploaded 20 August 2019]

Abstract

In this work, we employed a computational fluid dynamics (CFD)-based model with a Eulerian multiphase approach to simulate the fluidization hydrodynamics in biomass gasification processes. Air was used as the gasifying/fluidizing agent and entered the gasifier at the bottom which subsequently fluidized the solid particles inside the reactor column. The momentum exchange related to the gas-phase was simulated by considering various viscous models (i.e., laminar and turbulence models of the re-normalisation group (RNG), k-ε and k-ω). The pressure drop gradient obtained by employing each viscous model was plotted for different superficial velocities and compared with the experimental data for validation. The turbulent model of RNG k-Ɛ was found to best represent the actual process. We also studied the effect of air distributor plates with different pore diameters (2, 3 and 5 mm) on the momentum of the fluidizing fluid. The plate with 3-mm pores showed larger turbulent viscosities above the surface. The effects of drag models (Syamlal–O’Brien, Gidaspow and energy minimum multi-scale method (EMMS) on the bed’s pressure drop as well as on the volume fractions of the solid particles were investigated. The Syamlal–O’Brien model was found to forecast bed pressure drops most consistently, with the pressure drops recorded throughout the experimental process. The formation of bubbles and their motion along the gasifier height in the presence of the turbulent flow was seen to follow a different pattern from with the laminar flow.
Keywords: gasification; fluidized bed; CFD; hydrodynamics; multiphase flow gasification; fluidized bed; CFD; hydrodynamics; multiphase flow
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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MDPI and ACS Style

Khezri, R.; Wan Ab Karim Ghani, W.A.; Masoudi Soltani, S.; Awang Biak, D.R.; Yunus, R.; Silas, K.; Shahbaz, M.; Rezaei Motlagh, S. Computational Fluid Dynamics Simulation of Gas–Solid Hydrodynamics in a Bubbling Fluidized-Bed Reactor: Effects of Air Distributor, Viscous and Drag Models. Processes 2019, 7, 524.

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