Mixing characterization in a slab tank

Due to safety requirements, slab tanks are often used to process radioactive materials. The configuration is that of a slit or a tank of rectangular cross section with very low aspect ratio. Due to its nonconventional geometry, very little is known about the slab tank mixing environment. To better understand it, experiments have been performed in a full scale standard configuration equipped with two stirrer shafts, each containing several axial impellers. To characterize the velocity field, mean and RMS turbulent velocities have been measured at several impeller speeds with a two-component Laser Doppler Anemometer (LDA). The LDA data have been supplemented with flow visualization, circulation time, and mixing time studies. Since the slab tank is often used as a precipitator, solids suspension studies have also been performed. The results of the various experiments will be presented and will be interpreted to elucidate slab tank dynamics. The implication to mixing efficiency will also be discussed