Fluid dynamic analysis in three-phase stirred tanks

The aim of this study is to measure the three characteristic agitator speeds (loading speed, complete dispersion speed and just drawdown speed) in a mechanically agitated vessel containing three phases (gas, solid and liquid phases). The gas phase is air, the liquid phase is a water solution with 15% (by weight) concentration of glucose and the solid phase is made by particles of polyethylene that present two different mean values of diameter (dp = 3,025mm and dp = 4,025mm). The first system considered was a vessel agitated by only one impeller (Smith turbine) and the second system was one vessel agitated by two impellers (Smith turbine and pitched blade turbine). The aim of the experiment was to understand how the solid concentration, the volumetric gas flow rate and the mean diameter of the solid particles can affect the 3 characteristic speeds in the two different mechanically agitated systems. A comparison between the two system was made in different conditions of: - solid particles concentration - volumetric gas flow rate - diameter of the solid particles