A comparative investigation on bubble dynamics in gas–solid separation fluidized bed using Geldart A, B, D and Geldart A^- particle

Dense medium has a certain impact on the separation efficiency of gas–solid fluidized bed separation. Geldart A^- particle, a new type of dense medium, can effectively improve the expansion of the emulsion phase and the separation efficiency in the fluidized bed. This work is aimed to investigate the differences of bubble dynamics for Geldart A, B, D and A^- particle fluidized beds with digital image analysis technology in a two-dimensional gas–solid fluidized bed. The bubble number and size distributions are consistent with those in literature for Geldart A, B and D particle fluidized beds. The bubble size is smaller for Geldart A^- particle fluidized beds. Due to the bubble rupture neglected in the Darton bubble growth model, a new correlation based Darton bubble growth model has been extended, which has approximately 15% accuracy region. Additionally, the bubble rising velocity was studied. The extended Davidson correlation, which has approximately 15% accuracy region, is a good method to predict the bubble rising velocity. Thus, the separation efficiency of gas–solid fluidized bed separation could be improved for Geldart A^- particle.