A DYNAMIC-MODEL OF THE HYDRODYNAMICS OF A LIQUID FLUIDIZED-BED

The efficient design, operation, and scale up of novel fluidized bed b ioreactors for direct coal liquefaction require detailed knowledge of reactor axial pressure drop, dispersion of the solid and liquid phases , and the particle size distribution as a function of axial position. In this paper, a fully predictive mathematical description of the hydr odynamics of a liquid fluidized bed, containing no adjustable paramete rs, is developed. This model is compared with experimental data obtain ed from a liquid fluidized bed containing finely divided coal particle s. The emphasis of this study is the development of a predictive mathe matical model to appropriately describe the transient behavior of such systems subject to changes in the liquid superficial velocity. The un derlying mathematical treatment of this problem is based on particle m ass transport mechanisms of dispersion and convection. The particle ve locity responsible for convection and the particle dispersion coeffici ents were evaluated using correlations developed previously. The compa rison of the model predictions with the experimental data for coal flu idized beds shows excellent agreement.