Gas holdup and volumetric liquid-phase mass transfer coefficient in bubble column with draught tube and with gas dispersion into tube.

Koide, Kozo; Kurematsu, Katsumi; Iwamoto, Satoshi; Iwata, Yutaka; Horibe, Kazuyoshi

doi:10.1252/jcej.16.413

Cited by 63 publications

(28 citation statements)

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“…Thus, it can be generally assumed that the reactor scale can significantly influence the two-phase gas-liquid flow, especially in the heterogeneous regime. To provide higher values of circulation (11) and (12) specific air flow rate (vvm) constant in Eqs. (19) and (20) velocity (shorter mixing times) and better distribution of the gas phase (higher gas hold-up), it is suitable to use larger reactor volumes to avoid unfavorable influences of the gas hold-up reduction due to wall effects.…”

Section: Introductionmentioning

confidence: 99%

Oxygen transfer in three scales of concentric tube airlift bioreactors

Cerri

Badino

2010

Biochemical Engineering Journal

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Section: Introductionmentioning

confidence: 99%

Oxygen transfer in three scales of concentric tube airlift bioreactors

Cerri

Badino

2010

Biochemical Engineering Journal

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“…Base: In the vast majority of airlift designs, the bottom connection zone between the riser and downcomer is very simple. The design of this section may sometimes influence gas holdup, liquid velocity, and solid phase flow (3,4).…”

Section: Reactor Morphologymentioning

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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“…However, studies on AR_ALRs are quite scarce [15]- [18] although Koide et al [17], [18] have shown in their experimental studies that AR_ALRs have in fact higher gas holdups and mass transfer rates than CR_ALRs, especially for liquid phase systems which have frothing properties. The anti-frothing ability of the AR_ALRs is higher than CR_ALRs due to much more bubbles being entrained into the downcomer.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamics and Mass Transfer Performance of Annulus-Rising Airlift Reactor — The Effect of Reactor Scale

Han¹,

Лаари²,

Koiranen³

2017

IJCEA

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Abstract-Hydrodynamic and mass transfer characteristics of an annulus-rising airlift reactor (AR_ALR) were investigated with experimental and CFD simulation methods. An Eulerian model with two bubble phases was developed to simulate the AR_ALR in three circulation flow regimes. 3D steady state CFD simulations were performed under different gas superficial velocities (U g ). Good agreements on gas holdup and volumetric mass transfer coefficient were obtained over the range of the studied U g . The simulated averaged liquid velocities in AR_ALR with different scales were compared and accounted for the influence of reactor scale on gas holdup. The three flow regimes in AR_ALR were captured well and are similar to those observed in experiments. The developed CFD model can be used to predict the hydrodynamics and mass transfer in AR_ALRs with different scales.Index Terms-Annulus-rising airlift reactor, CFD, mass transfer, scale-up effect. I. INTRODUCTIONAirlift loop reactors (ALRs) have received more and more attention in chemical, petrochemical and biochemical industries. They are used in fermentation, waste water purification, hydrogenation and exhaust-gas treatment [1], [2]. ALRs have some advantages over bubble columns such as enhanced mixing, mass and heat transfer, and suspension of particles with low energy consumption. The mild and constant shear environment in ALRs, contrary to mixing tanks, is preferable for bioprocesses with fragile particles [3].ALRs usually are composed of a riser with a gas feed, and a downcomer where the liquid phase flows downwards. An enlarged expansion, called gas separator, is often placed on the top of the column in order to achieve good separation of gas and liquid phases. Generally, two types of ALRs, an internal-loop airlift reactor (IL-ALR) and an external-loop airlift reactor (EL-ALR), are classified according to the arrangement of the riser and the downcomer. For IL-ALR, two operating modes can be used which are the gas-feeding in the draft tube (center-rising airlift reactor, CR_ALR) and the gas feeding in the annulus (annulus-rising airlift reactor, AR_ALR) modes.A large number of studies on CR_ALRs have been reported and great achievements have been obtained with experimental [4]- [8] AR_ALRs have in fact higher gas holdups and mass transfer rates than CR_ALRs, especially for liquid phase systems which have frothing properties. The anti-frothing ability of the AR_ALRs is higher than CR_ALRs due to much more bubbles being entrained into the downcomer. Moreover, most of the studies, typically in bioprocesses, have been performed in bench-scale (1 -10 L) ALRs [15] and are limited to the specified aeration rates [2]. The yield of desired products may be lower than expected even in pilot-scale applications [19] due to the effects of the reactor scale, aeration and agitation. It is therefore necessary to investigate the effect of aeration and scale on hydrodynamics and mass transfer in AR_ALR so that the performance of the reactor would satisfy the process needs as well as pos...

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Gas holdup and volumetric liquid-phase mass transfer coefficient in bubble column with draught tube and with gas dispersion into tube.

Cited by 63 publications

References 0 publications

Oxygen transfer in three scales of concentric tube airlift bioreactors

Oxygen transfer in three scales of concentric tube airlift bioreactors

Bioreactors: Airlift Reactors

Hydrodynamics and Mass Transfer Performance of Annulus-Rising Airlift Reactor — The Effect of Reactor Scale

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