Mixed solid/dispersed phase particles in multiphase fluidised beds. II: Stability at laminar to turbulent flow scales

An energetics model is developed to explain the retention of a dispersed ph ase fluid within a multiphase fluidised bed, in terms of the behaviour of m ixed phase particles, or composite particles of the solid and dispersed flu id phases. The energy available for mixed phase particle rupture is determi ned by analogy with the theories of Kolmogorov and Hinze for isolated dropl et rupture in turbulent flow, and of Taylor, Sprow, Shinnar and others for droplet rupture in laminar flow fields. The resulting available energy surf aces are compared to the work required for mixed-phase particle rupture, as determined in Part I (Niven et al., 1998. Chemical Engineering Science, su bmitted for publication). The overall model is used to explain experimental observations of the diesel-sand system fluidised by either water or water and nitrogen. The model may also be applied to other multiphase systems, in cluding ex situ soil washing, tar sand extraction, and colloid-stabilised e mulsions. (C) 2000 Elsevier Science Ltd. All rights reserved.