Comparing a range of impellers for “stirring as foam disruption”

Boon, Lotte A.; Hoeks, Frans W. J. M. M.; Lans, R. G. J. M. van der; Bujalski, W.; Wolff, Menno O.; Nienow, Alvin W.

doi:10.1016/s1369-703x(01)00180-2

Cited by 21 publications

(14 citation statements)

References 11 publications

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“…(e) Use antifoam to control foaming as appropriate. In addition, if an up-pumping impeller is used at the top as recommended in (a), it may be useful if higher air flow rates are employed for reducing the tendency to foaming, as it has been shown to do with bacterial fermentations (Boon et al 2002). (f) Use an aspect ratio at around 1.0-1.3, thus reducing the zone of potential bubble burst damage as a proportion of the total volume of the bioreactor without compromising good blending.…”

Section: Carbon Dioxide/osmolalitymentioning

confidence: 99%

Reactor Engineering in Large Scale Animal Cell Culture

2006

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This article mainly addresses the issues associated with the engineering of large-scale free suspension culture in agitated bioreactors >10,000 L because they have become the system of choice industrially. It is particularly concerned with problems that become increasingly important as the scale increases. However, very few papers have been written that are actually based on such large-scale studies and the few that do rarely address any of the issues quantitatively. Hence, it is necessary very often to extrapolate from small-scale work and this review tries to pull the two types of study together. It is shown that 'shear sensitivity' due to agitation and bursting bubbles is no longer considered a major problem. Homogeneity becomes increasingly important with respect to pH and nutrients at the largest scale and sub-surface feeding is recommended despite 'cleaning in place' concerns. There are still major questions with cell retention/recycle systems at these scales, either because of fouling, of capacity or of potential and different 'shear sensitivity' questions. Fed-batch operation gives rise to cell densities that have led to the use of oxygen and enriched air to meet oxygen demands. This strategy, in turn, gives rise to a CO 2 evolution rate that impacts on pH control, pCO 2 and osmolality. These interactions are difficult to resolve but if higher sparge and agitation intensities could be used to achieve the necessary oxygen transfer, the problem would largely disappear. Thus, the perception of 'shear sensitivity' is still impacting on the development of animal cell culture at the commercial scale. Microcarrier culture is also briefly addressed. Finally, some recommendations for bioreactor configuration and operating strategy are given.

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Section: Carbon Dioxide/osmolalitymentioning

confidence: 99%

Reactor Engineering in Large Scale Animal Cell Culture

2006

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“…This would be easiest by moving the upper impeller closer to the dispersion level of the broth. However, some impellers-particularly hydrofoil impellers-are more effective than others in foam disruption with respect to power draw [3,6,12]. The standard Rushton turbine (ratio of impeller diameter over tank diameter (D/T)=0.33) shows a rather poor performance with regard to SAFD [2].…”

Section: Introductionmentioning

confidence: 99%

Scale-up of stirring as foam disruption (SAFD) to industrial scale

Hoeks¹,

Boon²,

Studer³

et al. 2003

J IND MICROBIOL BIOTECHNOL

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Foam disruption by agitation-the stirring as foam disruption (SAFD) technique-was scaled up to pilot and production scale using Rushton turbines and an up-pumping hydrofoil impeller, the Scaba 3SHP1. The dominating mechanism behind SAFD-foam entrainment-was also demonstrated at production scale. The mechanistic model for SAFD defines a fictitious liquid velocity generated by the (upper) impeller near the dispersion surface, which is correlated with complete foam disruption. This model proved to be scalable, thus enabling the model to be used for the design of SAFD applications. Axial upward pumping impellers appeared to be more effective with respect to SAFD than Rushton turbines, as demonstrated by retrofitting a 12,000 l bioreactor, i.e. the triple Rushton configuration was compared with a mixed impeller configuration from Scaba with a 20% lower ungassed power draw. The retrofitted impeller configuration allowed 10% more broth without risking excessive foaming. In this way a substantial increase in the volumetric productivity of the bioreactor was achieved. Design recommendations for the application of SAFD are given in this paper. Using these recommendations for the design of a 30,000 l scale bioreactor, almost foamless Escherichia coli fermentations were realised.

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“…Others studies have been achieved with Newtonian fluids: Junker et al (2000) for Rushton, Maxflo T, CD-6 and HE-3 impellers; Boon et al (2002) for 6SRGT, A315 and 3SHP1 impellers with dual arrangement; Hokes et al (2003) for Rushton turbine, Scaba 3SHP1 and 6SRGT impellers.…”

Section: Introductionmentioning

confidence: 99%

Mixing in shear thinning fluids

Ameur

Bouzit

2012

Braz. J. Chem. Eng.

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-In the present study, a CFD characterization of the flow generated by curved-blade impellers in a cylindrical unbaffled vessel was carried out. The tank diameter was 300 mm, with a flat bottom. The liquid height was equal to the vessel diameter. The fluids simulated have a shear thinning behavior. Analyses concern the effect of the impeller speed, the fluid rheology and the number of impeller blades on the induced flow patterns and the power consumption. The predictions were compared with literature data and a satisfactory agreement was found.

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Comparing a range of impellers for “stirring as foam disruption”

Cited by 21 publications

References 11 publications

Reactor Engineering in Large Scale Animal Cell Culture

Reactor Engineering in Large Scale Animal Cell Culture

Scale-up of stirring as foam disruption (SAFD) to industrial scale

Mixing in shear thinning fluids

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