EXPANSION OF FLUIDIZED BEDS IN SLUG FLOW

Derivations are presented showing that the maximum height of a fluidized bed in slug flow is given by the equation Hmax/H0 = 1 + (U-U0/0·35 √ (gD) where H is height, U is superficial gas velocity, g is gravitational acceleration, D is bed diameter and the subscript 0 refers to minimum fluidization. Over 60 sets of data are analysed and found to give experimental verification of the equation. Support is also given to the sometimes questioned assumptions that gas flow in the emulsion phase remains near U0 and that absolute bubble rise velocity in slug flow is given by the expression uA = 0·35 √ (gD) + 1·0 (U - U0. Analysis is given which predicts the cyclical movement of the bed surface due to the slugs breaking through. This analysis gives further insight into the importance of maximum bed height in applying the two-phase theory. © 1969.