Modeling and Simulation of Hydrodynamic Bubble‐Liquid Turbulent Flows in Bubble‐Column Reactors

Li, Xiangli; Li, Guohui

doi:10.1002/ceat.201600074

Cited by 8 publications

(5 citation statements)

References 43 publications

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“…Second, the small‐orifice sparger provided higher gas holdup than the large‐orifice one . This corresponded to the different diameters of bubbles produced by the orifices : small bubbles rose to the liquid surface more slowly than large bubbles and eventually stayed longer in the column.…”

Section: Resultsmentioning

confidence: 99%

Gas Sparger Orifice Sizes and Solid Particle Characteristics in a Bubble Column – Relative Effect on Hydrodynamics and Mass Transfer

et al. 2017

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The relative effects of the size of gas sparger orifices and properties of solid particles on gas-liquid mass transfer are not yet fully understood. Here, the impact of sparger orifice sizes, solid particle shapes, and their loading amounts in a bubble column reactor on the absorption of oxygen in tap water was investigated. Their influence on the mass transfer coefficient and bubble hydrodynamic parameters was evaluated. The results show that the addition of solid particles can have both positive and negative effects on hydrodynamics and mass transfer, depending on the orifice size of the gas sparger. The introduction of ring-shaped solid particles can improve the mass transfer rate by up to 28 % without requiring any significant additional power.

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Section: Resultsmentioning

confidence: 99%

Gas Sparger Orifice Sizes and Solid Particle Characteristics in a Bubble Column – Relative Effect on Hydrodynamics and Mass Transfer

et al. 2017

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“…It is due to the size of bubbles generated by those air diffusers. H-1.2 diffuse has the largest orifice size, while F-sand has the smallest one, which resulted in the smallest bubble size, 3.14-4.90 mm, as discussed by previous studies [4,27]. Similar trends were noted in ALR for small orifice diffusers, F-sand, C-sand, and H-0.3, higher Vg resulted in larger bubbles, 3.27-6.27 mm (see Figure 3b).…”

Section: Bubble Diameter (D 32 ) and Rising Velocity (U B )mentioning

confidence: 51%

“…Figure 3 illustrated the bubble size as Sauter's mean value at different investigated diffusers and gas velocity (Vg) in both BCR and ALR. In BCR, it can be observed that the air bubbles distribute between 3.14 and 11.28 mm, while larger bubbles were obtained in the higher gas flow, regardless of diffuser classes due to the bubble coalesce and high-pressure promotion at a higher flow (see Figure 3a) [24,27]. In general observation, smaller bubbles were observed from the use of a smaller orifice size diffuser (see Table 1) through the bubble formation phenomena.…”

Section: Bubble Diameter (D 32 ) and Rising Velocity (U B )mentioning

confidence: 82%

Effective Analysis of Different Gas Diffusers on Bubble Hydrodynamics in Bubble Column and Airlift Reactors towards Mass Transfer Enhancement

et al. 2021

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Even bubble column reactors (BCR) and airlift reactors (ALR) have been developed in terms of various related aspects towards mass transfer enhancement, the effective analysis of gas diffuser types on mass transfer and gas–liquid hydrodynamic characteristics is still limited. Therefore, the present study aims to analyze the relative effect of different types of air diffusers on bubble hydrodynamics and mass transfer performance to understand their behaviors and define the best type. The experiments were conducted by varying different diffuser types, reactor types (BCR and ALR), and superficial gas velocity (Vg) (0.12 to 1.00 cm/s). Five air diffusers including commercial fine sand (F-sand) and coarse sand (C-sand) diffusers, and acrylic perforated diffusers with orifice sizes of 0.3 mm (H-0.3), 0.6 mm (H-0.6), and 1.2 mm (H-1.2), were used in this study. For every condition, it was analyzed in terms of bubble hydrodynamics and oxygen mass transfer coefficient (KLa). Lastly, the selected diffusers that provided the highest KLa coefficient were evaluated with a solid media addition case. The results of both reactor classes showed that F-sand, the smallest orifice diffuser, showed the smallest air bubbles (3.14–4.90 mm) compared to other diffusers, followed by C-sand, which larger about 22–28% on average than F-sand. ALR exhibited a better ability to maintain smaller bubbles than BCR. Moreover, F-sand and C-sand diffusers showed a slower rising velocity through their smaller bubbles and the tiny bubble recirculation in ALR. Using F-sand in ALR, the rising velocity is about 1.60–2.58 dm/s, which is slower than that in BCR about 39–54%. F-sand and C-sand were also found as the significant diffusers in terms of interfacial area and gas hold-up. Then, the KLa coefficient was estimated in every diffuser and reactor under the varying of Vg. Up to 270% higher KLa value was achieved from the use of F-sand and C-sand compared to other types due to their smaller bubbles generated/maintained and longer bubble retention time through slower rising velocity. After adding 10% ring shape plastic media into the reactors with F-sand and C-sand diffusers, a better performance was achieved in terms of KLa coefficient (up to 39%) as well as gas hold-up and liquid mixing. Lastly, ALR also had a larger portion of mixed flow pattern than BCR. This eventually promoted mass transfer by enhancing the mixed flow regime.

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“…Bubble columns are widely employed in the industry to conduct gas‐liquid and gas‐liquid‐solid catalytic reactions in view of their merits compared to stirred‐tank reactors which suffer from problems such as high power consumption per unit volume, shaft sealing at high pressures, shaft eccentric rotation in tall reactors, and high shear rates which cause damage to the shear‐sensitive cultures involved in biochemical reactions 1–3. Bubble columns exhibit excellent mass and heat transfer characteristics, besides their high mixing efficiencies, simple design (no moving parts), and uniform temperature distribution 4–7. Despite the above favorable attributes of bubble‐column reactors, attempts have been going on to improve their performance furthermore by: (i) improving their productivity via increasing the rate of slow diffusion‐controlled liquid‐solid reaction step involved in gas‐liquid‐solid reactions; (ii) raising the rate of heat removal in case of highly exothermic reactions to avoid the adverse effects of high temperatures.…”

Section: Introductionmentioning

confidence: 99%

Intensification of the Rate of Heat and Liquid‐Solid Mass Transfer at the Wall of a Bubble‐Column Reactor by Turbulence Promoters

et al. 2021

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Rates of heat and liquid‐solid mass transfer in a square bubble column with semicylindrical turbulence promoters at its wall were measured using the electrochemical technique in the bubbly flow regime. Turbulence promoters enhanced the wall liquid‐solid mass or analogous heat transfer coefficients and the corresponding volumetric mass transfer coefficients by factors up to 2.36 and 3.76, respectively, depending on the working conditions. The rate of liquid‐solid mass transfer was improved with increasing superficial gas velocity and decreasing turbulence promoter diameter. The importance of the turbulence promoters as a catalyst support and a built‐in cooler was highlighted. Power consumption measurements revealed that the gas‐sparged reactor outperforms the mechanically stirred reactor.

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Modeling and Simulation of Hydrodynamic Bubble‐Liquid Turbulent Flows in Bubble‐Column Reactors

Cited by 8 publications

References 43 publications

Gas Sparger Orifice Sizes and Solid Particle Characteristics in a Bubble Column – Relative Effect on Hydrodynamics and Mass Transfer

Gas Sparger Orifice Sizes and Solid Particle Characteristics in a Bubble Column – Relative Effect on Hydrodynamics and Mass Transfer

Effective Analysis of Different Gas Diffusers on Bubble Hydrodynamics in Bubble Column and Airlift Reactors towards Mass Transfer Enhancement

Intensification of the Rate of Heat and Liquid‐Solid Mass Transfer at the Wall of a Bubble‐Column Reactor by Turbulence Promoters

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