Improvement of foam breaking and oxygen-transfer performance in a stirred-tank fermenter

Takesono, Satoshi; Onodera, Masayuki; Toko, Kiyoshi; Yoshida, Masanori; Yamagiwa, Kazuaki; Ohkawa, Akira

doi:10.1007/s00449-005-0028-x

Cited by 17 publications

(4 citation statements)

References 15 publications

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“…To elucidate oxygen supply levels at various medium volumes (50, 100, and 250 mL) in 500 mL flasks, the volumetric oxygen transfer coefficient ( k L a ) was measured by a sulfite oxidation method with suitable modifications. Shake-flasks were filled with Na 2 SO 3 solution (0.2 N Na 2 SO 3 and 0.1 mM CuSO 4 ) and were shaken at 30 °C and 130 rpm.…”

Section: Methodsmentioning

confidence: 99%

Endogenous Ethanol Affects Biopolyester Molecular Weight in Recombinant Escherichia coli

et al. 2013

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In biopolyester synthesis, polyhydroxyalkanoate (PHA) synthase (PhaC) catalyzes the polymerization of PHA in bacterial cells, followed by a chain transfer (CT) reaction in which the PHA polymer chain is transferred from PhaC to a CT agent. Accordingly, the frequency of CT reaction determines PHA molecular weight. Previous studies have shown that exogenous alcohols are effective CT agents. This study aimed to clarify the effect of endogenous ethanol as a CT agent for poly[(R)-3-hydroxybutyrate] [P(3HB)] synthesis in recombinant Escherichia coli, by comparing with that of exogenous ethanol. Ethanol supplementation to the culture medium reduced P(3HB) molecular weights by up to 56% due to ethanol-induced CT reaction. NMR analysis of P(3HB) polymers purified from the culture supplemented with (13)C-labeled ethanol showed the formation of a covalent bond between ethanol and P(3HB) chain at the carboxyl end. Cultivation without ethanol supplementation resulted in the reduction of P(3HB) molecular weight with increasing host-produced ethanol depending on culture aeration. On the other hand, production in recombinant BW25113(ΔadhE), an alcohol dehydrogenase deletion strain, resulted in a 77% increase in molecular weight. Analysis of five E. coli strains revealed that the estimated number of CT reactions was correlated with ethanol production. These results demonstrate that host-produced ethanol acts as an equally effective CT agent as exogenous ethanol, and the control of ethanol production is important to regulate the PHA molecular weight.

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Section: Methodsmentioning

confidence: 99%

Endogenous Ethanol Affects Biopolyester Molecular Weight in Recombinant Escherichia coli

et al. 2013

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“…In the work of Kang et al, a foam breaker with synthetic sponge cylinders was developed. A synthetic sponge has a higher water‐absorbing capacity, which can intensify the liquid drainage of foams and accelerate bubble breakage …”

Section: Introductionmentioning

confidence: 99%

Numerical and experimental study of a novel aerodynamic foam breaker for foam drilling fluid

Cao

Zhuo

Liu

et al. 2019

Energy Science & Engineering

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Defoaming is a key technology for increasing the efficiency of foam drilling in petroleum engineering. To enhance the performance of a mechanical foam breaker in foam drilling, a novel aerodynamic foam breaker with two annular slits was investigated in this study. The computational fluid dynamics code of ANSYS Fluent was used to simulate the velocity and pressure distribution inside the foam breaker, and the optimum distance between the two annular slits was determined based on the simulation methods. Meanwhile, a series of experiments were conducted to test the actual performance of the foam breaker. The results demonstrate that various factors may affect the efficiency of the foam breaker, including the foam gas‐liquid ratio, basic liquid viscosity, and air supply method. A higher gas‐liquid ratio of the foam and air supply pressure result in a superior foam breaker performance. The viscosity of the foam liquid phase exhibits exactly the opposite behavior, meaning that the foam breaker more effectively destroys foam from a lower‐viscosity liquid. This study verifies the practicability of this novel aerodynamic foam breaker and discusses the effects of different parameters on the defoaming percentage, and this study can act as a reference and guidance for subsequent defoaming research.

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“…Mechanical foam breaker is preferable to chemical methods, avoiding problems such as changing the chemical and physical properties of the foam system which pollute the foam surfactant and reduce its foamability that the foam drilling fluid cannot be reused, or adverse effects on environment seen when foaming is controlled by the addition of antifoam agents (Pelton, 2002). A number of mechanical foam breakers have so far been proposed including high rotate centrifugal foam breaker (Vetoshkin, 2003), foambreaking cyclones (Guzman, 2005) and air jet breaker (Vetoshkin and Chagin, 2002), etc., (Satoshi et al, 2003;Takesono et al, 2006;Zagoskina and Sokovnin, 2001;Barigou, 2001;Satoshi et al, 2007;Deshpande and Barigou, 2000). However, most of these breakers are hardly practical for foam-breaking operation in high-rate gas bubbling systems of foam drilling fluid.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of the Laval Annular Mechanical Foam Breaker for Foam Drilling

Cao¹,

Liu²,

Wang³

2013

RJASET

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The Computational Fluid Dynamics (CFD) code, Fluent, is employed to simulate the flow phenomena inside the annular foam breaker in order to improve its performance. The numerical simulation results show that the value and the distribution of the negative pressure are very important for the annular foam breaker. The design of the Laval nozzle not only can increase the fluid velocity, but also can reduce the pressure value from -30.2 to -50.3 kPa compared with the common annular nozzle foam breaker. In order to improve the range of the internal negative pressure, the two-stage Laval annular foam breaker is designed in this study. The analysis results show the distance between the two annular slit have greatly influence on its performance. There is a small overlap area between the two negative pressure zones generated by the two annular slits. The smaller the value distance is, the larger the overlap zone is. When the value of the distance decreases to 50 mm, the minimum negative pressure can be reduced to approximately -65.5 kPa. Meanwhile, the range of the internal negative pressure is larger than the single Laval annular foam breaker, which is benefit to break foam.

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Improvement of foam breaking and oxygen-transfer performance in a stirred-tank fermenter

Cited by 17 publications

References 15 publications

Endogenous Ethanol Affects Biopolyester Molecular Weight in Recombinant Escherichia coli

Endogenous Ethanol Affects Biopolyester Molecular Weight in Recombinant Escherichia coli

Numerical and experimental study of a novel aerodynamic foam breaker for foam drilling fluid

Numerical Simulation of the Laval Annular Mechanical Foam Breaker for Foam Drilling

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