Oxygen mass transfer coefficient with sparged bubble size analysis in stir tank bioreactors

Abstract Bubble size has a key role in gas holdup and mass transfer in bubble column reactors. In order to have small and uniform bubbles, a new structure was designed; the reactor operates in two modes, with vibrating sparger and conventional bubble column in which sparger is fixed. In vibrating mode, the sparger vibrates gently during gas entering. The vibrating sparger performs like a paddle, resulting in a forced recirculation of gas–liquid inside the reactor; moreover, the bubble detachment is accelerated. The superficial gas velocity was between 0.003 and 0.013 ms− 1, and the vibration frequency was changed between 0 and 10.3 Hz. The bubble size was measured at three various positions of the reactor height by photographic method and using MATLAB 7.0.1 software. The mass transfer coefficient was determined by means of the dynamic gassing-out method. The results show that the bubbles were bigger in vibrating mode than those working without vibration. The bubble size decreases with increase in height from sparger. Gas holdup increased with increase in superficial gas velocity and vibration frequency. The effect of vibration increased the gas holdup with an average of 70% for all superficial gas velocities. Volumetric mass transfer coefficient was almost stable as vibration frequency increased.

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Effects of solid mass and size on gas holdup and oxygen mass transfer coefficient of a three‐phase air‐lift reactor

Journal of Environmental Science and Health Part A Environmental Science and Engineering and Toxicology ◽

10.1080/10934529409376175 ◽

1994 ◽

Vol 29 (10) ◽

pp. 2219-2227 ◽

Cited By ~ 1

Author(s):

K.S. Ro ◽

M.K. Singh

Keyword(s):

Mass Transfer ◽

Transfer Coefficient ◽

Mass Transfer Coefficient ◽

Gas Holdup ◽

Oxygen Mass Transfer ◽

Solid Mass ◽

Three Phase ◽

Air Lift Reactor ◽

Air Lift

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Oxygen Mass Transfer Coefficients in a Three-Phase Pulsed Plate Bioreactor

International Journal of Chemical Reactor Engineering ◽

10.2202/1542-6580.2248 ◽

2010 ◽

Vol 8 (1) ◽

Cited By ~ 2

Author(s):

K.V. Shetty ◽

G. Srinikethan

Keyword(s):

Mass Transfer ◽

Transfer Coefficient ◽

Mass Transfer Coefficient ◽

Immobilized Cells ◽

Fixed Bed ◽

Oxygen Mass Transfer ◽

Transfer Coefficients ◽

Mass Transfer Coefficients ◽

Three Phase ◽

Plate Column

Volumetric oxygen mass transfer coefficient is a decisive parameter for the selection of any contactor as an aerobic bioreactor. A pulsed plate column with fixed bed of solids in interplate spaces is a recent innovation in the field of immobilized cell bioreactors. Volumetric oxygen mass transfer coefficients are determined in a three-phase pulsed plate column involving air and water phases and with a fixed bed of glass particles, which can serve as a surface for cell immobilization packed in the interplate spaces. The volumetric mass transfer coefficients obtained in this column range from 0.067 to 0.1495 s-1 in the range of air superficial velocities from 0.011 to 0.047m/s and vibrational velocities from 0.825 to 6cm/s. Volumetric oxygen mass transfer coefficient has increased with the increase in superficial air velocity and vibrational velocity. Empirical correlation relating kLa with these variables was developed. The volumetric oxygen mass transfer coefficient values in the three-phase pulsed plate column are found to be similar or higher than the literature reported values for conventional two-phase pulsed plate columns. The values of volumetric oxygen mass transfer coefficients in the three-phase pulsed plate column are of higher order of magnitude than the literature reported values of volumetric oxygen mass transfer coefficient for many other three-phase gas-liquid-solid reactors. The pulsed plate column with fixed bed of solids is proven to have all the potential to be used as an aerobic bioreactor with immobilized cells due to its better gas-liquid mass transfer characteristics.

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