Particulate Science and Technology, Vol.22, No.4, 391-403, 2004
Non-Newtonian fluids in spout-fluid beds: Mass transfer coefficient at low Reynolds numbers
Following on from the work of Anabtawi et al. (2003), this study examined how the volumetric liquid-phase mass transfer coefficient, k(L)a, of oxygen in air in three-phase spout fluid beds was affected by varying the system parameters of bed height, bed diameter, gas velocity, and liquid velocity. The liquid used was 0.1% CMC solution, displaying a pseudo-plastic rheology, with 1.75mm glass spheres as packing. The values of the Sherwood number were lower than in previous studies (Anabtawi et al., 2003), in the range 9,000-186,000. Gas velocity had a similar effect on kLa as in a bubble column, with results also giving good agreement with previous work on two-phase and three-phase spouted bed systems. The correlation obtained for the effect of liquid velocity on k(L)a compared well with that of Schumpe et al. (1989). An increase in the height of packing increased kLa to the power of 0.319, with an increase in column diameter also causing an increase in kLa, which is in agreement with the results of Akita and Yoshida (1973).
Keywords:spout-fluid bed;fluidization;mass transfer coefficient;CMC solution;three-phase systems;non-Newtonian systems