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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 48221 (06)
- University: Sharif University of Technology
- Department: Chemical and Petroleum Engineering
- Advisor(s): Molaei Dehkordi, Asghar
- Abstract:
- Because of unique features and numerous advantages, the fluidized bed has been considered as one of the most widely used process equipment in various industries. However, many aspects of the hydrodynamic behavior of the equipment are unknown. In this study, using simulation tool, hydrodynamic behavior and mixing process of binary solids particle mixture in the tapered fluidized bed with a jet at the entrance were studied. Eulerian – Eulerian multifluid model incorporating the kinetic theory of granular flow is used to simulate the gas-solid multiphase flow with open-source MFIX software. To increase the accuracy of the results standard k-ε turbulence model was used. Validation of results was conducted with the experimental data presented by Huilin et al. (2003b). The results showed good agreement with the experimental data. The effect of time averaging has been studied and time interval 20-30 seconds was chosen for the averaged time. Hydrodynamic and mixing behavior of the binary mixture of solid particles in the tapered fluidized bed was conducted by examining the solid particles circulation pattern and using segregation number index and effect of various factors including the geometry and the head of bed angle, initial static bed height of the solid particles, the initial arrangement of solid phases, the effect of operating conditions of jet nozzle such as diameter and jet nozzle location as well as the effect of the entrance two jets were investigated. The results show that in general, the solid particles at the center of tapered fluidized bed of the bed have rising flow and falling flow at near the wall which helps to circulate the particles at different heights depending on the circumstances and solid particles flow pattern can approach to symmetrical flow pattern. The results of particles mixing study showed that, equilibrium mixing in the tapered fluidized bed will be greater than the cylindrical bed. By increasing the diameter of the jet nozzle at a constant speed as well as increase the speed of jet at a constant head angle, the equilibrium mixing increases. To investigate the effect of initial arrangement of solid phases on mixing of solid particles, relationship of the segregation number index modified and new relationship to calculate mixing in the horizontal arrangement of the particles, has been submitted. The results showed that the initial arrangement of particles as well as the initial static bed height of the solid particles will not have considerable effect on the equilibrium mixing. Furthermore, investigation of the effect of two jet nozzles, showed that the adding a nozzle in the gas distributor compared with single jet nozzle increases the equilibrium mixing and reduces the time to reach equilibrium
- Keywords:
- Binary Mixture ; Eulerian-Eulerian Approach ; Mixing ; Solid-Gas Fluidized Bed ; Tapered Fluidized Bed ; Jet Nozzle
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