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Direct Particle Simulation Of Air And Particle Motions In Bubbling Fluidized Bed

Posted on:2007-05-24Degree:MasterType:Thesis
Country:ChinaCandidate:J K WuFull Text:PDF
GTID:2121360185987671Subject:Engineering Thermal Physics
Abstract/Summary:PDF Full Text Request
Fluidized beds are widely used in chemical, petroleum, energy, material, environment and other industry segments. The main advantage of fluidized beds is that the motion of solids increases the heat transfer rate to the walls, and the temperature in fluidized bed can be controlled easily. Besides it's convenient to add and upload the reactor material, and the efficiency of fluidized bed reactor is great. Nowadays, a great deal of experiments and theory studies have been carried out all over the world. While the hydrodynamic of solid particle fluidization is complicate, at present it's impossible to clarify the mechanism of all phenomena in fluidized bed.In this thesis Eular-Lagrangian method is performed to investigate the bubbling fluidized bed, the collision of particles is simulated with soft sphere model developed by Tsuji et al. The relationships between bed pressure loss and the bed bottom-air velocity are figured out, calculated results are fairly in good agreement with formerly experiment data. Statistical dispersing characteristics of both air and particle mean velocity have been analyzed. Particle motion around the bubble is researched and the moving tracks caused by bubble motion are obtained. Particle movement in the bubble eruption area is analyzed too, the results show that particles at the top of bubble reach higher position than the particles in the weak of the bubble do after the bubble eruption happens. Then the distribution of the void fraction was researched.Secondly, fluidized bed with binary and third mixture of particles with various diameters and densities are investigated, the result show that mixture of various particles enhance the strength of particles turbulence. Besides, the distributions of different particles in fluidized bed are researched.Finally, the calculation of particle motion was extended to three dimensions. It is observed that the particle turbulence increased while take into account the collision with the front and rear walls.
Keywords/Search Tags:Bubbling fluidized bed, Discrete particle method, Soft particle model
PDF Full Text Request
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