Bubble Formation on a Single Orifice in a Gas Solid Fluidized Bed Using Digital Image Analysis

Digital Image Analysis (DIA) has been employed to characterize the time evolution of a bubble injected from a single orifice into a pseudo 2-dimensional gas-solid fluidized bed. The injected bubble diameter increased with the square root of time before detachment. During bubble free flight in the bed, its diameter remains approximately constant. The center of mass of the bubble increases with the second power of the time. The results show that the classical models for bubble injection can predict the time evolution of bubble diameter, and its center of mass. Bubble tends to elongate during injection and after detachment its height to width aspect ratio decreases. Image analyzing results were also used for the study of gas leakage from the bubble to emulsion phase, and it has been shown that the dense phase expands up to 1.04 times the minimum fluidization condition for large bubbles. The expansion ratio of the dense phase increases linearly with bubble diameter.