Laboratory of Chemical Engineering, Delft University of Technology, The Netherlands
Abstract:
In gas-fluidized beds bubbling starts when the voids formed by the oscillating bottom layer of the bed exceed a minimal size. The so-called vibration criterion derived predicts the porosity at the bubble point in close agreement with the experimental data. Comparison of the other criteria proposed in the literature on the basis of the transition number shows that the voids formed under the critical conditions will grow and that stable bubbles can exist.
