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CFD Simulation of Gas Bubble Size Distribution and Rising Velocity in Tapered Fluidized Beds

A’rabi, Yavar | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55535 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Molaei Dehkordi, Asghar
  7. Abstract:
  8. The solid-gas fluidized beds are widely used in the petrochemical, energy, chemical, and metallurgical industries. Because they provide fast heat- and mass-transfer rate along with good mixing behavior of solids. Because of carry over of fine particles in columnar beds, the application of tapered fluidized beds has become widespread in industires due to the variation in axial velocity along the bed height. In this work, a 2D two-fluid model (TFM) incorporating the kinetic theory of granular flow (KTGF) was used to simulate the hydrodynamic behavior of gas bubbles in a tapered fluidized bed. The experimental data obtained in the laboratory were compared with the simulation results and good agreement was observed. The effects of the inlet air velocity, apex angle, particle size, particle density, particle size and density (Geldart group), initial bed height, operating temperature and pressure, and the drag models were investigated. Syamlal O’Brien’s drag model provides the best predictions for the gas bubble behavior. As the particle density, particle size, operating pressure, and the initial bed height increased, both the bubble diameter and rising velocity decreased. The bubble diameter decreased as the apex angle increased, however, no significant changes were observed in the bubble rising velocity. Both the bubble diameter and rising velocity were much larger for Geldart A particles. The operating temperature had no significant influence on the hydrodynamic behavior of gas bubbles
  9. Keywords:
  10. Tapered Fluidized Bed ; Computational Fluid Dynamics (CFD) ; Gas Bubbles ; Bubble Size Distribution ; Rising Bubble ; Gas Bubbles Rising Velocity ; Solid-Gas Fluidized Bed

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