Fluidization of spherical particle beds with non-Newtonian suspensions

Fluidization of spherical particle beds with shear thinning fine particle suspensions has been investigated experimentally. The beds were composed of uniform glass, steel, and lead balls; the test liquids were suspensions of kaolin or titanium dioxide in water solutions of glycerol. The flow curves of suspension were approximated using power law and Herschel-Bulkley flow models. Overall, 61 particle-suspension-column systems were tested giving a Reynolds number range of 7 x 10(-4) <= Re-nt <= 43. Minimum fluidization velocities and the expansion of beds have been evaluated in creeping and transition flow regions. The equations based on power law and Herschel-Bulkley flow models have been suggested for the prediction of bed expansion course. It follows from the results obtained that the test suspensions can be treated as power law fluids and the use of Herschel-Bulkley flow model seems to be unnecessary for predicative calculations. Concerning the bed expansion relationships based on a capillary bed model, the best results are obtained if the dependence of tortuosity on the power law index is taken into account.