Hydrodynamic behaviour and oxygen transfer rate in a pilot plant fermenter. I. Influence of viscosity

Abstract

AbstractThe effects of varying impeller speed, aeration rate and viscosity on mixing time, power consumption and oxygen transfer rate were studied in the pilot plant fermenter. The rheological behaviour of erythromycin fermentation broth was simulated by colloidal starch solutions at apparent viscosities of 0.02–0.20 Pa/s. The volumetric oxygen transfer rate coefficient was determined by the sulphite and static method. The experimental results showed that at low viscosities, up to of 0.02 Pa/s, the suitable range of impeller speed is 250–300 min−1 at aeration rate 0.6–0.8 VVM from the point of view of power input (2.6–2.8 kW/m3) and sufficient coefficient KLa (160–200 h−1). At viscosities higher than 0.02 Pa/s (with pseudoplastical character) the suitable range of impeller speed is 300–350 min−1 at the same aeration rate. Then the power input for mixing is 3.0–3.5 kW/m3 and the coefficient KLa ∼ 50 h−1.