Gas Hold-Up in Vessel with Dual Impellers and Different Baffles

Abstract

The influence of impellers system, baffles system and type of liquid on gas hold-up in a vessel has been presented in this paper. The analysis of gas hold-up was conducted on the basis of the data obtained in the vessel. The vessel used in the study was of inner diameter D = 0.288 m, and it was filled with liquid up to a height of H = 0.576 m. The vessel used in the study was equipped in four planar standard baffles or 24 vertical tubular baffles located on the circuit. A high-speed impellers system, consisting of two impellers located on the shaft, was used to agitate the liquid. The six gas–liquid systems were tested. The gas used in the study was air. The liquids were distilled water, aqueous solutions of NaCl (concentration c = 0.4 kmol/m3 or 0.8 kmol/m3), aqueous solution of sucrose (concentration c = 2.5% mass., 5% mass.), 5% mass. aqueous solution of sucrose and yeast suspension concentration ys = 1% mass. The obtained set of over 1600 experimental points allowed to derive the equations describing the effect of gas flow number Kg, Weber number We and parameter Y (for air–water and air–aqueous solution of NaCl) and Kg, We, c and ys (for air–water, air–aqueous solution of sucrose and air–yeast suspension–aqueous solution of sucrose) on gas hold-up. These equations do not have equivalents in the literature.

Keywords

• mixing
• gas–liquid
• gas–biophase–liquid
• gas hold-up
• mixing
• configuration of the impellers