Measurement of the overall volumetric oxygen transfer coefficient in alkane-aqueous dispersions

✍ Scribed by Leslie DC Correia; Kim G Clarke

• Publisher: Wiley (John Wiley & Sons)
• Year: 2009
• Tongue: English
• Weight: 143 KB
• Volume: 84
• Category: Article
• ISSN: 0268-2575
• DOI: 10.1002/jctb.2246

✦ Synopsis

Abstract

BACKGROUND: A reliable procedure for the determination of the volumetric oxygen transfer coefficient (K~L~a) in hydrocarbon–aqueous dispersions is critical to the assessment of oxygen transfer in hydrocarbon‐based bioprocesses. The pressure step procedure (PSP) and gassing out procedure (GOP) for K~L~a determination were evaluated in n‐C~10–13~ alkane–aqueous dispersions over agitation rates (600 to 1200 rpm) and alkane concentrations (up to 20%) typical of hydrocarbon‐based bioprocesses.

RESULTS: K~L~a from the procedures diverged progressively as agitation increased, with K~L~a underprediction attenuated at high alkane. At 1200 rpm and 5% alkane, K~L~a from the GOP was underpredicted by 49%. Compared with K~L~a from the PSP, K~L~a from the PSP without nitrogen transport was the same, but K~L~a from the PSP without response lag (PSP‐lag) was underpredicted by approximately 50% at 1200 rpm. Moreover, K~L~a from the PSP‐lag was lower than K~L~a from the GOP, except at 1200 rpm and alkane concentration up to 5%.

CONCLUSION: The PSP was superior to the GOP in alkane–aqueous dispersions, particularly at extreme agitation and low alkane concentrations. This was attributable to the probe response lag and the non‐uniformity of gas composition inherent in the GOP and independent of the rate of coincident nitrogen transport. Copyright © 2009 Society of Chemical Industry