DUST FILTRATION IN GRANULAR BEDS (FLUIDIZATION, FLUID, ELECTROSTATIC, MECHANICS).
Item
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Title
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DUST FILTRATION IN GRANULAR BEDS (FLUIDIZATION, FLUID, ELECTROSTATIC, MECHANICS).
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Identifier
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AAI8423059
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identifier
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8423059
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Creator
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GAL, ELI.
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Contributor
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Gabriel Tardos | Robert Pfeffer
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Date
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1984
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Language
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English
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Publisher
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City University of New York.
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Subject
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Engineering, Chemical
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Abstract
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During the present work an experimental and theoretical study on granular bed filtration was conducted. A filtration model predicting single sphere and total bed efficiencies based on trajectory calculation of dust particles in the voids of granular bed was developed for the domain where inertia effects are dominant. The model used the flow field in a bed of spheres arranged in a body centered cubic array for which the filtration efficiency was found to be a function of a modified Stokes number defined by St' = StxF. The function F depends only on the Reynolds number Re and it is the ratio of two dimensionless velocities. The value of the function F can be found experimentally or predicted from the Ergun correlation to be F = 1 + 0.0157Re. The filtration efficiency calculated using the model, agrees well with experimental results obtained in beds of dense cubic packing of spheres especially at relatively low Reynolds numbers Re 0.01. The prediction of the theoretical model also agrees well with experimental data for randomly packed beds at low porosities and low Reynolds numbers.;A new type of granular bed filter the rotating fluidized bed filter (RFBF) was developed. It was demonstrated during the present research that the device operates continuously at high gas throughputs and using dielectric bed materials it experiences strong electrostatic and inertia effects. Also high collection efficiencies, 99.9% for particles larger than 1.0 micron and 90% for particles 0.3-0.5 (mu)m in diameter, were obtained during extensive research and it was shown that the high efficiency is mainly due to the inertia of the particles and to the electrostatic charge generated on the granules. Since high collection efficiencies were obtained using relatively shallow beds, the total pressure drop was found to be low even though the gas velocity through the bed was high. A new pilot size RFBF was designed: the new system is expected to be easy to control and to have efficiency of 99.9% for all particles larger than 0.3 (mu)m.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Chemical Engineering
