STUDY OF HYDRODYNAMIC BEHAVIOUR OF FLUIDIZED-BED REACTOR AND EFFECTS OF VARIOUS DRAG MODELS

摘要

The flow behavior of a two-dimensional gas-solid fluidized bed reactor was investigated. CFD simulation results from commercial CFD softwares such as ANSYS CFX5.7 and FLUENT, were compared to those results obtained experimentally [1] from the literature. A multi-fluid Eulerian model is applied in order to simulate the gas-solid flow. Momentum exchange coefficients were calculated by specifying the drag functions. Various drag functions including Syamlal-O’Brien and Gidaspow are applied. The kinetic energy lost during interparticle collisions was characterized by specifying the restitution coefficient values. A comparison of the modeling prediction and experimental measurements taken from the literature on the bed expansion ratio and qualitative gas-solid flow pattern indicated reasonable agreement. Bed expansion ratio predicted from simulation results showed good agreement with the experimental results and Pressure drop predicted showed a relatively close agreement with the experimental measurements at superficial gas velocity of 0.38 m/s. higher than the minimum fluidization velocity, Umf. Further experimental and modeling efforts are required in a comparable time and space resolution for the validation of CFD models on simulating flow in fluidized-bed reactors.