FUNDAMENTAL-STUDIES ON THE HYDRODYNAMICS AND MIXING OF GAS AND SOLID IN A DOWNER REACTOR

The effect of flow direction on hydrodynamics and mixing in the upflow and downflow circulating fluidized beds is discussed in details. Simi lar profiles of gas and solids velocities and solids concentration are found in both risers and downers. When the flow is in the direction o f gravity (downer), the radial profiles of gas and particle velocity a re more uniform than that in the riser, the solids mixing is very smal l and the flow pattern approaches plug flow, while the flow is against gravity(riser), the solids backmixing significantly increase and the flow pattern is far from plug flow. Among many of factors the now dire ction has the largest influence on hydrodynamics and axial mixing of g as and solids.