THEORETICAL AND EXPERIMENTAL BUBBLE FORMATION AT A SINGLE ORIFICE IN A 2-DIMENSIONAL GAS-FLUIDIZED BED

An earlier developed, first principles hydrodynamic model of gas-fluidized beds has been employed to study theoretically bubble formation at a single orifice in a two-dimensional bed. For several orifice discharge rates, theoretically predicted bubble sizes, formation times and shapes have been compared with experimental data obtained from triggered photographs. Besides, the present experimental and theoretical results were compared with predictions from two approximate models reported in the literature which are based on an idealized picture of the process of bubble formation. The advanced hydrodynamic model appears to predict the experimentally observed diameters, formation times and shapes of bubbles quite satisfactorily. The observed and calculated bubble diameters fall between the predictions from the two approximate models. Both the experimental and theoretical results clearly indicate that a strong leakage of bubble gas into the surrounding porous emulsion phase occurs, especially during the initial stage of bubble formation.