Chemical Engineering Research & Design, Vol.83, No.A11, 1311-1318, 2005
Torque measurements in aerated powders using a mechanically stirred fluidized bed rheometer (msFBR)
This paper reports oil a study of the flow properties of two aerated/fluidized granular materials by means of torque measurements using a mechanically stirred fluidized bed rheometer (msFBR). The paper presents the experimental procedures developed to test two different materials below the minimum fluidization condition and when the powders are just fluidized. The dependency of the torque measurements upon impeller speed and stirring time was anal sed. The effect of changing rate of aeration and impeller depth in the bed was also systematically investigated. Results reported here were obtained oil an alumina powder and on ballotini belonging to Geldart group A and B respectively. Below minimum fluidization, the torque profiles obtained for both powders were independent of impeller speed. With increasing impeller depth the torque profiles resembled the normal stress profiles in silos. At minimum fluidization condition, the torque was found to be dependent oil the impeller speed and found to increase linearly with increasing impeller depth.