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Prediction of the hydrodynamics of slightly wet suspended particles

Tuesday 6th January 2009 - 14:50 to 15:15
INI Seminar Room 1
Suspension of slightly wet particles is a feature of many industrial processes, for example, oil-wet catalyst are undesirably produced in high temperature FCC units, water and steam are injected into fluidized catalyst to control exothermic reaction, which are then regenerated by inert gases in a fluidized bed stripper, solutions are sprayed into fluidized bed for particle coating, wet grains are fluidized in biomass gasification and drying. In a slightly wet and dense suspension, the liquid bridges between particles result in the reduction of interparticle friction (lubrication) by switching the frictional contacts to fluid shear resistance, while collisional contacts dissipate energy in the liquid bridges and particles. Therefore, in order to simulate the flow hydrodynamics in wet suspension, it is required to have constitutive equations capable of predicting the inter-particle interactions in such condition. In this paper we first present experimental evidence on the critical effects of liquid presence on the hydrodynamics of a dense bubbling fluidized bed. In the second part we present a new constitutive equation for the particle stress tensor that allows for the descriptions of the interaction between slightly wet particles, we then incorporated the developed equation into a two-fluid model based on the Kinetic Theory of Granular Flow (KTGF) to study the flow characteristics in a solid-gas suspension at slightly wet condition.
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University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons