1998 Volume 31 Issue 5 Pages 714-721
The hydrodynamics of a circulating fluidized bed with a bubbling bed section separated by an inner rim baffle are examined both by experiment and mathematical analysis. To maintain sufficient solids holdup in the 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 baffle is greatly increased. Investigation into the baffle dimensions shows that the variation of the baffle clearance has little effect on the solids holdup in the upper section when the clearance is greater than a certain value, whereas the variation of the baffle height has a significant effect on the solids holdup in the upper section, i.e. the lower the baffle height, the higher solids holdup. A hydrodynamic model is developed based on the mass balance and the pressure balance of the solids circulation loop. With respect to gas-solids flow behavior in the upper section, the clustering suspension and the core-annulus flow are taken into account; for the lower section, a bubbling fluidized bed model is included. By comparing the calculated results with the experimental ones, the model is found to predict fairly well the gas-solids flow behavior of the compact bubbling-circulating fluidized bed.