CFD Modelling of a Fluidized Bed Gasifier; Effects of Drag Model and Bed Heights

Abstract:

One of the unresolved issues in using the gasifier is the inability to determine the occurrence of the transition regime of fluidized bed. In modeling gas-solid phase, drag force is one of the main mechanisms for inter-phase momentum transfer. Thus, a simulation of fluidized bed was developed to study the effect of using various drag models over different bed height of H/D ratio such as 0.5, 1 and 2. A two dimensional model using Eulerian-Granular Multiphase Model (EGM) based on two fluid models have been used to simulate hydrodynamics of a bubbling fluidized beds. Gas-solid interactions are modeled via inter-phase of a drag model. The drag correlations of Gidaspow, Wen Yu, Syamlal-O'Brien, Hill Koch Ladd (HKL) and Representative Unit Cell (RUC) were implemented to simulate the interaction between phases. From this study, we found that different H/D ratio such as 0.5, 1 and 2 yields different volume fraction as increasing bed height slows kinetic transport of particle sand to the upper side of the bed. Besides that, different H/D ratio also resulted in different velocity vector. The results also show that Wen Yu and Syamlal-O'Brien are sufficient enough in detecting the change from one regime to another regardless of the bed height.

• Periodical: Applied Mechanics and Materials (Volume 699)
• Pages: 730-735
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.699.730
• Online since: November 2014
• Authors: Kamariah Md Isa, Kahar Osman, Nik Rosli Abdullah, Azfarizal Mukhtar, Nor Fadzilah Othman
• Keywords: Bed Height, Computational Fluid Dynamics (CFD), Drag Force, Eulerian-Granular Model (EGM), Fluidized Bed, Gasifier

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