Hydrodynamic studies in sectionalised external loop air lift reactors

ABSTRACT

External loop air lift reactor (EL-ALR) is widely used for multiphase reactions. They offer lower pressure drop and good heat and mass transfer rates compared to conventional bubble column reactors. In the case of fermentation applications where a medium is highly viscous and coalescing in nature, sectionalisation of riser helps in the improvement of the interfacial area as well as the reduction in liquid-phase backmixing. The present work deals with the measurement of the gas hold-up, mixing time, liquid dispersion, Sauter mean bubble diameter over a broad range of superficial gas velocities in sectionalised EL-ALR. Effects of electrolytes and surfactants have also been studied. Different plate designs have been studied for the sectionalisation. The correlations have been proposed for the gas hold-up, liquid circulation velocity, Sauter mean bubble diameter for superficial gas velocities.

Abbreviations: EL-ALR: external loop air lift reactor; IL-ALR: internal loop air lift reactor; ADC: analog to digital converter; DAC: digital to analog converter.

KEYWORDS:

• Sectionalised external loop air lift reactor
• gas hold-up
• mixing time
• liquid dispersion coefficient
• interfacial area

Acknowledgment

SMT would like to thank workshop superintendent Mr. A.S Desai and Prof P.V Jadhave for helping with the design of the EL-ALR in the lab scale.

Disclosure statement

No potential conflict of interest was reported by the authors.