NUMERICAL MODELING OF FLUIDIZED BED

Hongbo Shi
2017
This work focuses on validation of a commercial computational fluid dynamics (CFD) software ANSYS Fluent 16.2 applied to multi-phase modeling of fluidized beds. A two-phase Eulerian-Eulerian based model is used to numerically reproduce experiments carried out by Taghipour, F. et al (Chem. Eng. Sci., 60(24), 2005, 6857-6867). The influence of the model dimension (2D & 3D), flow regimes models (laminar & turbulent), model parameters (specularity coefficient responsible for particle-wall
more » ... n and restitution coefficient characterizing particle-particle interaction) and computational grids were investigated. The Syamlal-O'Brien and Gidaspow gas-solid drag submodels were tested. The comparison of numerical and experiment data showed that 2D simulations overpredict experimental data. 3D simulations showed good agreement between numerical calculations and experimentally measured void fraction profiles inside the bed. Results of 2D and 3D simulations revealed that the turbulence has a minor influence on the fluidized bed structure. However, it significantly affects the gas phase velocity in the upstream region of a reactor. At the same time, it was shown that a combination of E-E model parameters such as the specularity coefficient, numerical grid resolution and discretisation scheme for convective terms can lead to a good agreement between 2D CFD simulations and experimental data. Additionally, the influence of heterogeneous reactions has been studied between gas phase and solid phase inside a fluidized bed using E-E model. It was shown that heterogeneous chemical reactions have significant impact on the fluidization regimes due to local increase in the gas flow rate. This effect should be taken into account by design of chemical reactors with heterogeneous chemical reactions, e.g. fluidized bed combustors, boilers and gasifiers. ii
doi:10.7939/r3w37m88h fatcat:pd3rthq7hfantpe53hipjhefae