Behaviour of solid particles in viscous non-Newtonian solutions: settling velocity, wall effects and bed expansion in solid-liquid fluidized beds

Abstract

Settling velocities of particles in viscous non-Newtonian pseudoplastic solutions were measured. Spherical particles of glass and stainless steel were used. Aqueous solution of carboxymethyl cellulose (CMC) in the concentration range of 0.2 to 2 wt.% was used as the liquid phase. The settling velocities were measured in nine different columns with internal diameter in the range of 9 - 200 mm. The wall effect was investigated by varying the ratio of particle diameter to column diameter in the range of 0.05 to 0.78. Experiments were also performed for settling of particles in viscous Newtonian solutions of glycerol. The particle Reynolds number was varied in the range of 2 × 10⁻³ to 150. A correlation was obtained for the wall effect as a function of diameter ratio and the particle Reynolds number. Bed expansion was investigated in the case of solid-liquid fluidized bed and using non-Newtonian liquids Two glass particles of 1.65 and 3.1 mm were fluidized using the aqueous solutions of CMC. The bed was of 76 mm internal diameter. The expansion characteristics have been satisfactorily correlated.