Bubble characteristics and mass transfer in an airlift reactor with multiple net draft tubes

Tung, Hung-Ping; Tu, C.-C.; Chang, Y.-Y.; Wu, Wen‐Teng

doi:10.1007/s004490050450

Cited by 24 publications

(4 citation statements)

References 13 publications

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“…At other u sg , no significant differences between the two types of reactors were observed. An increase in the aeration rate from 1 to 1.5 cm s -1 induced liquid circulation rate and mass transfer between gas and liquid phase in the system [12] which facilitated the removal of metabolic gases such as oxygen, preventing the accumulation of such gases, avoiding potential adverse effects on the growth rate [13]. The mixing of liquid caused a more homogeneity between the medium and cell which resulted Airlift system…”

Section: Effect Of Aeration Ratementioning

confidence: 99%

Comparison between Airlift Photobioreactor and Bubble Column for Skeletonema Costatum Cultivation

Monkonsit¹,

Powtongsook²,

Pavasant

2011

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The cultivation of diatom Skeletonema costatum was achieved in airlift photobioreactor and the system performance was compared to that of bubble column. The standard F/2 medium (Guillard’s medium) for typical diatom cultivation could only yield the best growth character when the silicon concentration increased 4 times the normal value. In terms of cell growth, the airlift photobioreactor provided better performance than the bubble column where the maximum cell concentration, specific growth rate, and productivity in the airlift were 4.6 x 106 cell mL-1, 0.07 h-1, and 6.4 x 104 cell s-1 compared with 1.8 x 106 cell mL-1, 0.04 h-1, and 2.2 x 104 cell s-1 in the bubble column of the same size (3L) and operated at the same aeration rate (superficial velocity = 1.5 cm s-1) and light intensity (34 μmol photons m−2 s−1). This was because the airlift photobioreactor allowed circulatory flow in the system which helps prevent cell precipitation and enhance light utilization efficiency. The optimal operating conditions in the airlift system which was found most optimal to cell growth were: the ratio between downcomer and riser cross sectional area (Ad:Ar) of 3.27, superficial gas velocity 1.5 cm s−1 and the light intensity 34 μmol photons m−2 s−1. Preliminary economical assessment on the cultivation of S. costatum in airlift system compared with that in bubble column was carried out, whereas the analysis for nutritional values of the obtained biomass indicated relatively high protein content

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Section: Effect Of Aeration Ratementioning

confidence: 99%

Comparison between Airlift Photobioreactor and Bubble Column for Skeletonema Costatum Cultivation

Monkonsit¹,

Powtongsook²,

Pavasant

2011

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“…In coalescing systems, however, the prevailing bubble size in the dispersion is controlled not by the initial bubble size produced by the sparger, but by an equilibrium between the bubble coalescence and breakage 1, 2. In relatively coalescing fluids, for identical values of the specific power input, the Sauter mean bubble diameter in airlift reactors tends to be smaller than in bubble columns because the rapid circulatory flow of liquid in airlift reactors helps to break up gas bubbles 1, 6. In airlift reactors, the size of the bubbles impact on the design of the gas–liquid separator zone 7.…”

Section: Introductionmentioning

confidence: 99%

Bubble size in a forced circulation loop reactor

Fadavi

Chisti

Chriastel

2007

J of Chemical Tech & Biotech

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BACKGROUND: The bubble size distribution in gas-liquid reactors influences gas holdup, residence time distribution, and gas-liquid interfacial area for mass transfer. This work reports on the effects of independently varied gas and liquid flow rates on steady-state bubble size distributions in a new design of forced circulation loop reactor operated with an air-water system. The reactor consisted of a cylindrical vessel (∼26 L nominal volume, gas-free aspect ratio ≈6, downcomer-to-riser cross-sectional area ratio of 0.493) with a concentric draft tube and an annular riser zone. Both gas and liquid were in forced flow through a sparger that had been designed for minimizing the bubble size.

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“…It therefore makes sense to try to bring into the ALR some of the characteristics of BCs in a controlled fashion. This was done by several authors (368)(369)(370)(371)(372)(373)(374)(375), who tested different perforated draft tubes in a DT-ALR. The perforations in the draft tube facilitated communication between the less-well aerated liquid in the downcomer and the better aerated riser.…”

Section: Alrs Using Mechanically Moved Internalsmentioning

confidence: 99%

Bioreactors: Airlift Reactors

Merchuk

Camacho

2010

Encyclopedia of Industrial Biotechnology

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ALRs are popular in modern bioprocess research and development and, in many cases, they have found industrial uses. The distinctive characteristics of ALRs are conferred by the fluid dynamics of the liquid‐gas or liquid gas‐solid mixtures: holdup, liquid velocity, and mixing in the riser, gas separator, and downcomer. Only a correct understanding of the interconnection of these regions can make possible the scale‐up of a laboratory device, to pilot or industrial size. Several correlations are available in the literature for the prediction of the fluid dynamic characteristics of the reactor and of the mass and heat transfer coefficients, and a selection is presented in this review. Significant progress has been made in the application of modern computational tools to the simulation and design of ALRs. In parallel, innovative and sophisticated methods have been applied to obtain a deeper insight into the mechanisms of fluid motion and the flow patterns in the reactor. However, no single research group has managed to cover all the variables over a wide range. The engineer confronting scale‐up or de novo design of an ALR must analyze the validity of the correlations and computation methods used for the calculations.

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Bubble characteristics and mass transfer in an airlift reactor with multiple net draft tubes

Cited by 24 publications

References 13 publications

Comparison between Airlift Photobioreactor and Bubble Column for Skeletonema Costatum Cultivation

Comparison between Airlift Photobioreactor and Bubble Column for Skeletonema Costatum Cultivation

Bubble size in a forced circulation loop reactor

Bioreactors: Airlift Reactors

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