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Simulation of Solids Mixing Process in Tapered Fluidized Beds

Mardanloo, Peyman | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55511 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Molaei Dehkordi, Asghar
  7. Abstract:
  8. There is extensive use of solid-gas fluidized beds in the petrochemical, energy, chemical, and metallurgical industries. They provide fast heat- and mass-transfer because of the good mixing of solids. Tapered fluidized beds (TFBR) are more appropriate for this type of particle because they have axial velocity changes. This feature allows large particles to remain at the bottom of the bed and fine particles near the bed surface. In this work, the process of the solids mixing in a two-dimensional tapered fluidized bed with a bottom diameter of0/07 m and a height of 0.7 m was studied using computational fluid dynamics (CFD) techniques and applying a two-fluid model approach. The solids mixing was evaluated using the statistical Lacey mixing index. In this regard, the effects of superficial gas velocity, apex angle, solids fraction, operating temperature and pressure, particle density, initial bed height, solids layout and the drag model, on the mixing index were investigated and verified using ourown experimental data. The simulation results show that the minimum fluidity velocity is a key and significant parameter on the solids mixing. Moreover factors such as decreasing the superficial gas velocity, increasing the volume fraction of heavy particles, increasing pressure, decreasing the apex angle, increasing the density ratio of particles, increasing the initial height of the bed, which reduce the mixing index and vice versa. Inaddition, factors such as operating temperature and the drag coefficient did not have much effect on the value of the minimum fluidization velocity and, consequently, on the particle mixing index.
  9. Keywords:
  10. Tapered Fluidized Bed ; Mixing Index ; Computational Fluid Dynamics (CFD) ; Solids Mixing and Segregation ; Two-Fluid Flow ; Solid-Gas Fluidized Bed

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