Hydrodynamics of a Multi‐Stage Internal Loop Airlift Reactor

Li, Shaoguo; Qi, Tao; Zhang, Yi; Liu, Changhou

doi:10.1002/ceat.200700414

Cited by 10 publications

(5 citation statements)

References 24 publications

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“…[8,20] The hydrodynamics and mass transfer characteristics in ALRs have been extensively studied. [19,[21][22][23][24][25][26][27][28][29][30][31][32][33][34] How to enhance the mass transfer performance of ALRs is becoming an important issue in practical applications. In gas-liquid two-phase flow, the interphase mass transfer is dependent on the mass transfer rate and specific interfacial area.…”

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confidence: 99%

Gas holdup, bubble size distribution, and mass transfer in an airlift reactor with ceramic membrane and perforated plate distributor

et al. 2023

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The airlift reactor is one of the most commonly used gas–liquid two‐phase reactors in chemical and biological processes. The objective of this study is to generate different‐sized bubbles in an internal loop airlift reactor and characterize the behaviours of the bubbly flows. The bubble size, gas holdup, liquid circulation velocity, and the volumetric mass transfer coefficient of gas–liquid two‐phase co‐current flow in an internal loop airlift reactor equipped with a ceramic membrane module (CMM) and a perforated‐plate distributor (PPD) are measured. Experimental results show that CMM can generate small bubbles with Sauter mean diameter d32 less than 2.5 mm. As the liquid inlet velocity increases, the bubble size decreases and the gas holdup increases. In contrast, PPD can generate large bubbles with 4 mm < d32 < 10 mm. The bubble size and liquid circulation velocity increase as the superficial gas velocity increases. Multiscale bubbles with 0.5 mm < d32 < 10 mm can be generated by the CMM and PPD together. The volumetric mass transfer coefficient kLa of the multiscale bubbles is 0.033–0.062 s−1, while that of small bubbles is 0.011–0.057 s−1. Under the same flow rate of oxygen, the kLa of the multiscale bubbles increases by up to 160% in comparison to that of the small bubbles. Finally, empirical correlations for kLa are obtained.

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confidence: 99%

Gas holdup, bubble size distribution, and mass transfer in an airlift reactor with ceramic membrane and perforated plate distributor

et al. 2023

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“…Generally, small bubbles could intensify the mass transfer. Hence, several methods to reduce the bubble diameter have been studied [35][36][37]. Cutting the large bubbles to smaller ones by a wire or wire mesh which is set on the rising path is a convenient and cheap method compared with designing new trays or gas distributors.…”

Section: Bubble Cutting Behaviours With Mass Transfermentioning

confidence: 99%

Interactions between gas–liquid mass transfer and bubble behaviours

et al. 2019

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Interactions between gas–liquid mass transfer and bubble behaviours were investigated to improve the understanding of the relationship between the two sides. The CO 2 /N 2 -water system was applied to study the bubble behaviours based on the volume-of-fluid (VOF) model. The mass transfer conditions were taken into consideration when the fluid field was analysed. The bubble behaviours were compared with and without mass transfer. The results show that the absolute slopes of the curves for mass fraction inside the single rising bubbles, with diameters from 3 to 6 mm, decrease from 0.09325 to 0.02818. It means that small single bubbles have higher mass transfer efficiency. The daughter bubbles of cutting behaviour and initial side-by-side bubbles of coalescence behaviour also perform better than the initial large bubbles and coalesced bubbles, respectively. The bubble behaviours affect the mass transfer process. However, the latter also reacts upon the former. The critical intervals between the side-by-side bubbles decrease from 2.0 to 0.9 mm when the bubble diameter changes from 3 to 7 mm. For the coalescence behaviour without mass transfer, the critical intervals are larger because there is no influence of concentration around the bubbles on the bubble motion. The coalescence of cut daughter bubbles is also influenced by the concentration. It was suggested that the interaction between the gas–liquid mass transfer and bubble behaviours cannot be ignored.

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“…Moreover, the bubble size and gas holdup in the second and third stages were almost radially uniform at low superficial gas velocity. Li et al [18] also measured the local hydrodynamics in a three-stage ILAR using dual electrical resistivity probes and conductivity cells. The Zuber and Findlay drift flux model [19] was used to express the correlation of slip velocity with the total gas-liquid velocity, and it fitted the experimental data very well.…”

Section: Introductionmentioning

confidence: 99%

“…A detailed study of the local hydrodynamic characteristics in each stage, such as bubble size and liquid circulating velocity, can help us better understand the multistage ILAR. The work of Li et al [17,18] provided valuable insight for related research. Behin [20] investigated the mixing performance of a modified airlift loop reactor with a double-draft tube using the classical tracer response technique.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Draft Tubes on the Mass Transfer and Mixing Performance of a Pilot-Scale Internal-Loop Airlift Reactor

Wang,

Cheng,

Yuan

et al. 2023

Processes

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The hydrodynamic characteristics, mass transfer, and mixing performance of three different reactors, a bubble column reactor (BCR), a single-stage internal-loop airlift reactor (SSALR), and a four-stage internal-loop airlift reactor (FSALR), were investigated systematically through cold model experiments to explore the influence of draft tube configurations on the pilot-scale internal-loop airlift reactor (ILAR). The findings indicated that the BCR yielded a higher gas holdup and mass transfer coefficient due to its longer bubble residence time. Segmenting the draft tube improved the gas holdup in both the riser and downcomer, and the overall gas holdup in the downcomer increased by 9%. Compared with the SSALR, the mass transfer coefficient of the FSALR in the riser and downcomer increased by 10.2% and 9.3% on average, respectively. In addition, a higher liquid circulating velocity was obtained with the ILARs due to a higher gas holdup difference between the riser and the downcomer. Specifically, the liquid circulating velocity of the FSALR was 134.1% higher than that of the BCR and 15.8% higher than that of the SSALR. The mixing time of the ILARs was reduced due to more intense overall circulation. The mixing effect of the FSALR was the best. The mixing time was reduced by 70.2% and 51.3% compared with the BCR and SSALR for UG ranging from 4.0 cm/s to 9.1 cm/s, respectively. Empirical correlations were proposed for the gas holdup, liquid circulating velocity, mass transfer coefficient, and mixing time on the superficial gas velocity, and agreement with experimental data was satisfactory.

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Hydrodynamics of a Multi‐Stage Internal Loop Airlift Reactor

Cited by 10 publications

References 24 publications

Gas holdup, bubble size distribution, and mass transfer in an airlift reactor with ceramic membrane and perforated plate distributor

Gas holdup, bubble size distribution, and mass transfer in an airlift reactor with ceramic membrane and perforated plate distributor

Interactions between gas–liquid mass transfer and bubble behaviours

The Influence of Draft Tubes on the Mass Transfer and Mixing Performance of a Pilot-Scale Internal-Loop Airlift Reactor

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