Gas–liquid interfacial area and its influence on oxygen transfer coefficients in a simulated hydrocarbon bioprocess in a bubble column reactor

Abstract

AbstractBACKGROUNDThe overall volumetric oxygen transfer coefficient (KLa) is a critical parameter in evaluating the oxygen transfer in any aerobic bioprocess, e.g. a hydrocarbon‐based bioprocess. However, KLa comprises the oxygen transfer coefficient (KL) and the gas–liquid interfacial area, which are commonly affected by operating conditions of a bioprocess system. Therefore, this study has experimentally measured KLa and interfacial area in a model hydrocarbon‐based bioprocess under a range of operating conditions such as alkane (n‐C14–20) concentration (HC), solids (cornflour) loading (SL) and superficial gas (air) velocity (UG) in a bubble column reactor (BCR).RESULTSIt was found that the value of KLa increased with increasing UG in the BCR. The most significant impact on KLa was obtained through an increase in UG, where an increase of UG from 1 to 3 cm s−1 resulted in a 133% increase in KLa. Furthermore, a relationship between KLa and SL was identified and showed an optimal level at SL of 3 g L−1, indicating increased dispersion viscosity in the system as SL increased up to a certain point. However, HC showed an insignificant change in both the interfacial area and KLa with the range considered (2.5 to 20% v/v) of HC.CONCLUSIONSThis study expands on previous work by including an inert solid (cornflour) phase, which ultimately furthers our understanding of the effect of the solids type and size, and operational conditions (HC, SL and UG) on the behaviour of overall oxygen transfer in a bubble column hydrocarbon bioprocess.