A fluidization model using kinetic theory of granular flow

A fluidization model was developed using kinetic theory of granular flow. This model was applied to the simulation of bubbling fluidization, to the computation of fluidization of fine powders and to the computation of circulating fluidized beds.; The transport equations for the solid phase were derived using kinetic theory of granular flow. The starting point is the Boltzman integral-differential equation for particle velocity distribution. This approach produced explicit expressions for the solid pressure and solids viscosity.; The kinetic theory model when applied to bubbling fluidization is an improvement over the inviscid and the constant viscosity coefficient models used previously at IIT, Argonne National Laboratory and at Morgantown Energy Technology Center. The kinetic theory model does not show a disturbing damping of porosity oscillation with computation time reported previously.; A turbulent subgrid scale (SGS) model was applied to the gas phase turbulent flow with particles. The computations show that the turbulent model is necessary to obtain an agreement between the computations and literature experiments when the bed is fluidized by a high speed air jet.; An empirical cohesive force model was used to simulate fluidization of fine powders in an two-dimensional bed with a downward jet to force an agreement between the computed time-averaged porosities and the measured data. For better mixing of gases and contacting of gases and fine particles with a jet, a downward jet located inside the bed is the suggested geometry based on our experiment and computation.; The kinetic theory model and the turbulent SGS model were used to simulate the flow in IGT's (Institute of Gas Technology) riser and a PYROFLOW full-scale circulating fluidized bed. The predicted porosities in IGT's riser agree well with the measured data, except near the wall where experiment gave a denser region. The shapes of the radial profiles of the solid mass fluxes and the solid velocities are similar to the experimental profiles, but the computed values are about 25% lower. The reasonable computed results in the full-scale complete loop of a PYROFLOW circulating fluidized bed show that our computer model is able to predict the hydrodynamics in a circulating fluidized bed and is useful for the design of circulating fluidized beds.