Measurement of charge distribution around a rising bubble in a 2-D fluidized bed



A technique has been developed to determine the charge distribution around single rising bubbles in a two-dimensional fluidized bed. Four induction probes positioned flush with the outside wall of the column and connected to charge amplifiers record induced charge signals as bubbles pass. The charge distribution surrounding a single bubble is then reconstructed with the assumption that the bubble is symmetrical and that the charge around the bubble remains constant as it rises. The emulsion phase far from the bubble in a two-dimensional fluidized bed of glass beads was found to be charged negatively and, contrary to our previous assumptions, the charge density decreased gradually toward the bubble-dense phase interface, with a nearly zero charge density inside the bubble. The wake of the bubble is more negatively charged than the emulsion phase, supporting our previous speculations. © 2005 American Institute of Chemical Engineers AIChE J, 2006