Effects of superficial gas velocity on process dynamics in bioreactors

Abstract

Present work analyzes the flow hydrodynamics and mass transfer mechanisms in double Rushton and CD-6 impeller on wide range (0.0075–0.25 m/s) of superficial gas velocity (vg) in a gas-liquid phase bioreactor by employing computational fluid dynamics (CFD) technique. The volume averaged velocity magnitude and dissipation rate are found higher with increasing superficial gas velocity. Higher relative power draw (Pg/P0) is predicted in CD-6 than the Rushton impeller but no significant difference in volume averaged mass transfer coefficient (kLa) observed between these two types of impeller. The ratio of power draw with mass transfer coefficient has been found higher in CD-6 impeller (25–50 %) than the Rushton impeller.