Host: The Society of Chemical Engineers, Japan
Effect of vibration on bubble size and velocity was investigated experimentally in a two-dimensional vibro-fluidized bed, which included glass beads whose diameter was 43 micrometer (Geldart A particle). The fluidized bed was vibrated vertically with various vibration frequencies and amplitudes. The size and the rising velocity of bubbles distributed in the bed were measured. Furthermore, the bubble velocity was attempted to be correlated with its diameter. In the fluidized bed of the Geldart A particle, the measured bubble velocities scattered widely because of the sensitive effects of bubble coalescence and split. The bubble size and velocity could not be correlated well, when the vibration was not added. However, the correlation was improved by the addition of vertical vibration. Especially, when the vertical vibration of the amplitude larger than 1.5 mm was added, their correlation was improved significantly, as both horizontal and vertical components of bubble velocity decreased by the repression of bubble coalescences in the bed. As the amplitude of vertical vibration increased, the mean bubble diameter decreased, while the number of bubbles in the bed and the circularity of bubble shape increased.
At the small vibration amplitude, the bubble frequency strongly depended on the horizontal location of the bed and the location with high bubble frequency gradually shifted to the center with the bed height. On the other hand, the bubbles were evenly distributed in the bed at the large vibration amplitude. When the vibration with larger frequency was added onto the bed, the vibration started to influence the bubble behavior at the smaller vibration amplitude.
