The liquid–liquid homogeneity of a four‐phase simulated hydrocarbon‐based bioprocess in a bubble column reactor

BACKGROUND Bubble column reactors (BCRs) can be used for upgrading hydrocarbons to high‐value products via biological oxidation mediated by hydrocarbon‐metabolizing organisms. However, spatial phase dispersion homogeneity becomes a critical parameter which is needed for scale‐up calculations, especially in BCRs, where fluid mixing is only enacted through sparging. RESULTS In this study, the homogeneity of a multiphase hydrocarbon‐based bioprocess system was measured in a large bench‐scale BCR, with inner diameter of 15 cm and height of 90 cm. Multiphase dispersion measurement was done under a range of operational conditions such as hydrocarbon concentrations ( H C ), solids (deactivated yeast) loading ( S L ) and superficial gas velocities ( U G ). It was found that in a three‐phase system (air–water–hydrocarbon), high U G (2 cm s −1 ) was required to achieve homogeneity. However, in a four‐phase system (air–water–hydrocarbon–yeast), the addition of yeast changed the fluid properties (mainly the surface tension) and therefore enhanced the homogeneity at the minimum U G (1 cm s −1 ). CONCLUSIONS This article firstly illustrates multiphase homogeneity in multiphase systems, which needs to be examined when dispersion systems are being used, and secondly proposes a method for evaluating this parameter. © 2019 Society of Chemical Industry