HYDRODYNAMICS OF A CIRCULATING FLUIDIZED-BED WITH A BUBBLING BED SECTION SEPARATED BY AN INNER RIM BAFFLE

The hydrodynamics of a circulating fluidized bed with a bubbling bed s ection separated by an inner rim baffle are examined both by experimen t and mathematical analysis, To maintain sufficient solids holdup in t he upper section, the inner rim baffle was set up in the middle of the riser. It is found that the solids holdup in the section above the ba ffle is greatly increased, Investigation into the baffle dimensions sh ows that the variation of the baffle clearance has little effect on th e solids holdup in the upper section when the clearance is greater tha n a certain value, whereas the variation of the baffle height has a si gnificant effect on the solids holdup in the upper section, i,e, the l ower the baffle height, the higher solids holdup. A hydrodynamic model is developed based on the mass balance and the pressure balance of th e solids circulation loop, With respect to gas-solids now behavior in the upper section, the clustering suspension and the core-annulus flow are taken into account; for the lower section, a bubbling fluidized b ed model is included. By comparing the calculated results with the exp erimental ones, the model is found to predict fairly well the gas-soli ds flow behavior of the compact bubbling-circulating fluidized bed.