Determination of the overall volumetric mass transfer coefficient kLa, by a temperature dependent change of gas solubility

Eriksen, Niels Thomas; Iversen, Jens

doi:10.1007/bf00154317

Cited by 3 publications

(3 citation statements)

References 9 publications

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“…It is difficult to apply in this method the model represented by (4), because the value of saturation concentration of dissolved oxygen S C is usually unknown or difficult to estimate unless the nonlinear regression method is used as described in subsection C. Thus the transformed model represented by (9) is used in this case. Integrating of this model gives the following result:…”

Section: E Numerc Integral a K L Identification Methodsmentioning

confidence: 99%

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Probe dynamics influence on determination of volumetric oxygen transfer coefficient

Niedzwiedz

Laszczyk

2014

2014 19th International Conference on Methods and Models in Automation and Robotics (MMAR)

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This paper deals with practical aspects of volumetric oxygen transfer coefficient determination. The attention was paid to influence of dissolved oxygen probe dynamics on measurements. A new identification method of volumetric oxygen transfer coefficient was developed. This method involves numerical integral calculation. The new method and three other methods (graphical, logarithmic and regression) of determining volumetric oxygen transfer coefficient value were applied. The comparative simulation research was done using dissolved oxygen concentration model. All four methods were finally aplied to real biotechnological wastewater process with the activated sludge.

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Section: E Numerc Integral a K L Identification Methodsmentioning

confidence: 99%

“…The influence of different factors such as temperature, pressure, stirrer rotation speed and microorganisms concentration on K L a identification results are widely discussed and investigated [6,8,9,10,11]. The influence of the probe lag was also one of the research topic.…”

Section: Introductionmentioning

confidence: 99%

Probe dynamics influence on determination of volumetric oxygen transfer coefficient

Niedzwiedz

Laszczyk

2014

2014 19th International Conference on Methods and Models in Automation and Robotics (MMAR)

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“…In separate experiments, a rapid increase in temperature [11] was implemented manually from 15 to 25°C followed by a period of constant temperature under automatic control (Fig. 2).…”

Section: Mass Transfer Measurementsmentioning

confidence: 99%

Influence of impeller type on mass transfer in fermentation vessels

Junker

Stanik

Barna

et al. 1998

Bioprocess Engineering

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Radial¯ow Rushton impellers were compared qualitatively with axial¯ow hydrofoil impellers (Max¯o T and A315) at the pilot scale. Six types of impellers were compared for qualitative differences in mass transfer. Measurements were conducted using three model systems: water, glycerol and Melojel (soluble starch). Power measurements were obtained using watt transducers, which although limited in accuracy and prone to interferences, were able to provide useful qualitative monitoring results. While there was little effect of impeller type on mass transfer as measured by the rapid pressure increase technique, signi®cant qualitative differences were observed using the rapid temperature increase technique speci®cally for the Melojel and glycerol model systems. The Miller correlation, relating gassed-to-ungassed power, was used effectively to qualitatively evaluate the power drop upon gassing for both the model systems and a Streptomyces fermentation for the various impeller types.A high oxygen demand Streptomcyes fermentation then was conducted in fermenters possessing each type of impeller. Performance was not adequate with the A315 impellers pumping upwards and the small diameter Max¯o T impellers. Peak titers and pro®les of the estimated apparent broth viscosity varied depending upon the impeller type. Mass transfer rates generally declined with higher viscosities when other fermentation operating conditions where held constant. Overall, values for OUR, k L a, P g /V L and other calculated mass transfer and power input quantities for the A315 pumping upwards and undersized Max¯o T (D T /D I 2.3) impellers were at the lower end of the range obtained for the larger Max¯o T (D T /D I 1.8± 2.0) and A315 impellers pumping downwards. Rushton impellers generally behaved qualitatively similar to hydrofoil impellers based on these calculated quantities. List of symbolsa surface area per unit volume of bubbles, cm A1 g gravitational constant, m/s 2 k¯uid consistency index k L mass transfer coef®cient n power law index t m mixing time, s v b bulk velocity, m/s v s super®cial velocity of sparged air based on tank diameter, m/s A cross-sectional area of the tank, m 2 D I impeller diameter (tip to tip), m D T fermenter vessel diameter, m D oi diffusivity of oxygen in water (w), glycerol (g) andMelojel (m), cm 2 /s N impeller speed, s A1 N A aeration or¯ow number, Q/ND 3 I N Fr Froude number, N 2 /D I g N m Mixing number, 1/t m N N P Newton or power number, P 0 /(qN 3 D 5 I ) N Q generalized pumping number, Q P /ND 3 I N Re Reynold's number for impeller, ND 2 I q/l N Sc Schmidt number, l/qD oi P 0 ungassed power draw, kW P g gassed power draw, kW Q volumetric gas¯owrate, m 3 /s Q P volumetric pumping rate, v b A, m 3 /s V L ungassed liquid volume of tank, m 3 q liquid density, g/cm 3 l viscosity, mPa á s l a apparent viscosity, mPa á s c T average shear rate in stirred tank, s A1 r surface tension, dynes/cm 1 Introduction For aerobic fermentations, oxygen management is about 15±20% of all operating costs. Consequently, a modest impr...

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On-line determination of respiration rates of aquatic organisms in a mono-phase oxystat at steady-state dissolved oxygen tensions

Eriksen¹,

Iversen²

1997

Marine Biology

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Determination of the overall volumetric mass transfer coefficient kLa, by a temperature dependent change of gas solubility

Cited by 3 publications

References 9 publications

Probe dynamics influence on determination of volumetric oxygen transfer coefficient

Probe dynamics influence on determination of volumetric oxygen transfer coefficient

Influence of impeller type on mass transfer in fermentation vessels

On-line determination of respiration rates of aquatic organisms in a mono-phase oxystat at steady-state dissolved oxygen tensions

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