Oxygen transfer during batch cultivation in an airlift tower fermentor

1989 ◽  
Vol 54 (12) ◽  
pp. 3213-3219 ◽  
Author(s):  
František Potůček
Keyword(s):  
Experimental Data ◽  
Mass Transfer ◽  
Transfer Coefficient ◽  
Oxygen Transfer ◽  
Correlation Equation ◽  
Batch Cultivation ◽  
Growth Characteristics ◽  
Yeast Culture ◽  
Volumetric Mass Transfer Coefficient ◽  
Tower Fermentor

Oxygen transfer was studied in an airlift tower fermentor with motionless mixers (Kenics type). The intensity of oxygen transfer was characterized by its volumetric mass transfer coefficient, kLa, which was determined by the balance method. Experimental data of kLa were described by correlation equation and compared with results obtained for the airlift fermentor without motionless mixers with respect to energetic consumption. In addition, growth characteristics of the yeast culture Turulopsis ethanolitolerans cultivated on ethanol were also investigated.

Improvement of oxygen transfer efficiency in aerated ponds using liquid-film-assisted approach

2007 ◽  
Vol 55 (11) ◽  
pp. 183-191 ◽  
Author(s):  
H. Zhu ◽  
T. Imai ◽  
K. Tani ◽  
M. Ukita ◽  
M. Sekine ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Liquid Film ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Oxygen Transfer ◽  
Structural Parameters ◽  
Volumetric Mass Transfer Coefficient ◽  
Aeration System ◽  
Film Forming ◽  
Oxygen Transfer Efficiency

In aerated ponds, oxygen is generally supplied through either diffused or mechanical aeration means. Surface transfer and bubble transfer both contribute significantly to oxygen transfer in a diffused aeration system. In the present study, a liquid-film-forming apparatus (LFFA) is successfully developed on a laboratory scale to improve considerably the surface transfer via the unique liquid film transfer technique. The experimental results show that the volumetric mass transfer coefficient for LFFA alone is found to be as much as 5.3 times higher than that for water surface and that the total volumetric mass transfer coefficient for the liquid film aeration system increases by 37% in comparison with a conventional aeration system. Additionally, by tuning finely the structural parameters of the LFFA, it can also lead to high dissolved oxygen (DO) water with the DO percent saturation greater than 90%. More importantly, this result is accomplished by simply offering a single-pass aeration at a depth as shallow as 26 cm. As a result, the objective of economical energy consumption in aerated ponds can be realized by lowering the aeration depth without sacrificing the aeration efficiency. It is noteworthy that the data presented in this study are acquired either numerically or experimentally.

scholarly journals Gas–liquid mass transfer characteristics of aviation fuel scrubbing in an aircraft fuel tank

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Li Chaoyue ◽  
Feng Shiyu ◽  
Xu Lei ◽  
Peng Xiaotian ◽  
Yan Yan
Keyword(s):  
Mass Transfer ◽  
Dissolved Oxygen ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Oxygen Concentration ◽  
Gas Holdup ◽  
Aviation Fuel ◽  
Volumetric Mass Transfer Coefficient ◽  
Dissolved Oxygen Concentration ◽  
Liquid Mass Transfer

AbstractDissolved oxygen evolving from aviation fuel leads to an increase in the oxygen concentration in an inert aircraft fuel tank ullage that may increase the flammability of the tank. Aviation fuel scrubbing with nitrogen-enriched air (NEA) can largely reduce the amount of dissolved oxygen and counteract the adverse effect of oxygen evolution. The gas–liquid mass transfer characteristics of aviation fuel scrubbing are investigated using the computational fluid dynamics method, which is verified experimentally. The effects of the NEA bubble diameter, NEA superficial velocity and fuel load on oxygen transfer between NEA and aviation fuel are discussed. Findings from this work indicate that the descent rate of the average dissolved oxygen concentration, gas holdup distribution and volumetric mass transfer coefficient increase with increasing NEA superficial velocity but decrease with increasing bubble diameter and fuel load. When the bubble diameter varies from 1 to 4 mm, the maximum change of descent rate of dissolved oxygen concentration is 18.46%, the gas holdup is 8.73%, the oxygen volumetric mass transfer coefficient is 81.45%. When the NEA superficial velocities varies from 0.04 to 0.10 m/s, the maximum change of descent rate of dissolved oxygen concentration is 146.77%, the gas holdup is 77.14%, the oxygen volumetric mass transfer coefficient is 175.38%. When the fuel load varies from 35 to 80%, the maximum change of descent rate of dissolved oxygen concentration is 21.15%, the gas holdup is 49.54%, the oxygen volumetric mass transfer coefficient is 44.57%. These results provide a better understanding of the gas and liquid mass transfer characteristics of aviation fuel scrubbing in aircraft fuel tanks and can promote the optimal design of fuel scrubbing inerting systems.

Mass Transfer Coefficients during Steel Decarburization in a RH Degasser

2008 ◽  
Vol 273-276 ◽  
pp. 679-684
Author(s):  
Roberto Parreiras Tavares ◽  
André Afonso Nascimento ◽  
Henrique Loures Vale Pujatti
Keyword(s):  
Mass Transfer ◽  
Reynolds Number ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Gas Flow ◽  
Vacuum Chamber ◽  
Volumetric Mass Transfer Coefficient ◽  
Gas Flow Rate ◽  
Rh Process ◽  
Kinetics Of

The RH process is a secondary refining process that can simultaneously attain significant levels of removal of interstitial elements, such as carbon, nitrogen and hydrogen, from liquid steel. In the RH process, the decarburization rate plays a very important role in determining the productivity of the equipment. The kinetics of this reaction is controlled by mass transfer in the liquid phase. In the present work, a physical model of a RH degasser has been built and used in the study of the kinetics of decarburization. The effects of the gas flow rate and of the configurations of the nozzles used in the injection of the gas have been analyzed. The decarburization reaction of liquid steel was simulated using a reaction involving CO2 and caustic solutions. The concentration of CO2 in the solution was evaluated using pH measurements. Based on the experimental results, it was possible to estimate the reaction rate constant. A volumetric mass transfer coefficient was then calculated based on these rate constants and on the circulation rate of the liquid. The logarithm of the mass transfer coefficient showed a linear relationship with the logarithm of the gas flow rate. The slope of the line was found to vary according to the relevance of the reaction at the free surface in the vacuum chamber. A linear relationship between the volumetric mass transfer coefficient and the nozzle Reynolds number was also observed. The slopes of the lines changed according to the relative importance of the two reaction sites, gas-liquid interface in the upleg snorkel and in the vacuum. At higher Reynolds number, the reaction in the vacuum chamber tends to be more significant.

Volumetric mass transfer coefficient in the fermenter agitated by Rushton turbines of various diameters in coalescent batch

2019 ◽  
Vol 130 ◽  
pp. 968-977 ◽  
Author(s):  
Radim Petříček ◽  
Tomáš Moucha ◽  
Tomáš Kracík ◽  
František Jonáš Rejl ◽  
Lukáš Valenz ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Volumetric Mass Transfer Coefficient

scholarly journals The Influence of Optic and Polarographic Dissolved Oxygen Sensors Estimating the Volumetric Oxygen Mass Transfer Coefficient (KLa)

2016 ◽  
Vol 10 (8) ◽  
pp. 142 ◽  
Author(s):  
Gustavo Andrés Baquero-Rodríguez ◽  
Jaime A. Lara-Borrero
Keyword(s):  
Mass Transfer ◽  
Wastewater Treatment ◽  
Dissolved Oxygen ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Oxygen Transfer ◽  
Airflow Rate ◽  
Oxygen Probe ◽  
Aeration System ◽  
Oxygen Measurement

Aeration is usually the most energy intensive part of the wastewater treatment process. Optimizing the aeration system is essential for reducing energy costs. Field tests oriented to estimate parameters related to oxygen transfer are a common approach to compare aeration systems. The aim of this research is to assess the effect of dissolved oxygen probe lag on oxygen transfer parameter estimation. Experimental procedures regarding to process automation and control were applied to quantify dissolved oxygen probe lag. We have measured oxygen transfer in clean water, under a wide range of conditions (airflow rate, diffuser characteristics and diffuser density), with optic and polarographic sensors for dissolved oxygen measurement. The oxygen transfer was measured as per ASCE Standard procedures. Nonparametric statistical tests were used to compare the estimated volumetric mass transfer coefficient KLa with different sensors. According to the results, there is not significant influence of the probe lag (also known as time constant) or probe characteristics on the parameters used to assess oxygen transfer efficiency. This fact has great relevance in common practice of aerobic process for wastewater treatment because dissolved oxygen monitoring is used as an input for decision making related to the energy optimization in the aeration system. Findings from these tests contradict previous studies which claim that lag time in polarographic sensors for the dissolved oxygen measurement can bias estimate KLa.

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