(344g) Effect of Fluidized Bed Scale and Bed Height On Flow Regimes Transition Using Optical Probe and Pressure Transducer Measurements

Faraj Zaid, and Muthanna H. Al Dahhan, Department of Chemical and Biological Engineering, Missouri University of Science and Technology, Rolla, MO

 Different flow regimes are encountered in fluidized bed reactors. The reactor hydrodynamics and hence, performance change significantly as a result of flow regime change. It is very important to know what type flow regime the reactor is operating at and how to identify the boundaries of the flow regimes. Therefore, the reactor volume productivity, mixing, mass and heat transfer are affected by the prevailing flow regime. In this work pressure transducer and optical probe were used to measure and identify bubbly and churn turbulent flow regimes and their transitions in two different plexiglas fluidized beds (small scale 0.14 m and pilot plant scale of 0.44 m in ID) at different axial and radial positions. Pressure transducer was measured at the wall while optical probe was pleased at different radial position from the wall to the center of the bed. Statistical analyses have been performed on the time series measurement of these techniques for identifying the the flow regimes and their transitions.

Notable differences were observed in flow regimes transition along the bed axial and radial locations particularly among the sparger (Z/D=0.286) the fully developed flow (Z/D=1.7) and free band regions. There are some variations between the flow regime transitions obtained using pressure transducer at the wall and at local points inside the bed using optical probe at the studied bed heights. Detailed data and findings will be discussed and presented in this talk.  

 Keywords: Fluidized beds, optical probe, Pressure fluctuations, Flow regimes identification, Various transition velocities