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Influence of particle size distribution on fluidized bed hydrodynamics

University of British Columbia

Past literature has shown that the production efficiency of a fluidized bed can be affected by changing the particle size distribution. The hydrodynamics of fine particle fluidization were studied with FCC and glass bead powders which have different surface-volume mean particle diameter (40-110 μM) and particle size distributions (narrow cut, wide cut and bimodal) under ambient conditions. Increasing the mean particle size increases the minimum fluidization velocity, minimum bubbling velocity and dense phase velocity (U[sub d]) while decreasing the voidages at minimum fluidization and minimum bubbling and the dense phase voidage (∈[sub d]) as well as the fractional bubble free bed expansion. Increasing the particle size spread increases U[sub d] and decreases ∈[sub d] for FCC, but no clear conclusion can be made for glass bead powders. Increasing the static bed height decreases U[sub d] and ∈[sub d] of FCC powders though it has no effect on minimum fluidization and bubbling properties. The magnitude of pressure fluctuations increases with increasing superficial gas velocity and as the size spread of the FCC powder becomes more narrow. However, the frequency of fluctuations is independent of each of these factors. Therefore, the quality and production efficiency of the fluidization process should improve with the use of a wide and continuous size distribution powder.

Text

2010-08-30

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http://hdl.handle.net/2429/27891

Chemical and Biological Engineering

University of British Columbia

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