Hydrodynamics of fluidization: Experimental and theoretical bubble sizes in a two-dimensional bed with a jet

During the past three years we have developed a tentative cold bed hydrodynamic model for an idealized fluidized bed gasifier. The computer program calculates the pressure, the void fraction and the velocities for a single size solid and for a gas. The fluid bed never reaches a steady state, but continually oscillates, as bubbles form, rise through the bed and collapse on top of the bed. In this paper we show that the hydrodynamic model can predict bubbles forming in the fluidized bed. Photographically determined bubble sizes agree with the predicted bubble sizes. They increase with height of bed and with jet velocity. The model produces bubble splitting which agrees with observations at higher jet velocities.