Comparative Study of Mass Transfer and Bubble Hydrodynamic Parameters in Bubble Column Reactor: Physical Configurations and Operating Conditions

Sastaravet, Prajak; Chuenchaem, Chomthisa; Thaphet, Nawaporn; Chawaloesphonsiya, Nattawin; Painmanakul, Pisut

doi:10.4491/eer.2014.s1.013

Cited by 13 publications

(7 citation statements)

References 12 publications

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“…The same pitch area with a different number of orifices was used to evaluate the influent of the number of orifices. All five different diffusers are arranged for having different orifice diameters such as F-sand and C-sand orderly have a nominal pore size of fine and coarse orifice size approximately range 0.08-0.15 mm and 0.20-0.25 mm [13], respectively. Orifice diameters of H-0.3, H-0.6, and H-1.2 diffusers are 0.3, 0.6, and 1.2 mm, respectively.…”

Section: Gas Diffusersmentioning

confidence: 99%

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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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Section: Gas Diffusersmentioning

confidence: 99%

“…The tank-in-series model is also used to analyze the mixing performance of the column. The number of tank-in-series (N Tank ) was calculated using Equation (13). When the N Tank is unity, it indicates the perfect mixing flow regime in the column.…”

Section: Residence Time Distribution (Rtd) Techniquementioning

confidence: 99%

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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“…The low terminal rising velocity with solid media addition was directly associated with the smaller air bubble caused by the bubble break-up mechanism and the bubble captured with additional media. The condition with solid media possibly increased the bubble interfacial area (a) [23]. Therefore, this part aimed to determine bubble interfacial area in both reactors for selected solid media.…”

Section: Bubble Interfacial Area (A)mentioning

confidence: 99%

Relative Effect of Additional Solid Media on Bubble Hydrodynamics in Bubble Column and Airlift Reactors towards Mass Transfer Enhancement

et al. 2020

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Many researchers have focused on multi-phase reactor development for improving mass transfer performance. However, solid particle addition in gas–liquid contactor for better oxygen mass transfer performance is still limited. Hence, this study aims to analyze the relative effect of different types of local solid media on the bubble hydrodynamic characteristics towards mass transfer enhancement in bubble columns (BCR) and airlift reactors (ALR). This was investigated by varying solid media types (ring, sphere, cylinder, and square), solid loadings (0%–15%), and superficial gas velocities (Vg) (2.6–15.3 × 10−3 m/s) in terms of the bubble hydrodynamic and oxygen mass transfer parameters. The result showed that bubble size distribution in BCR and ALR with additional plastic media was smaller than that without media addition, approximately 22%–27% and 5%–29%, respectively, due to the increase of the bubble breaking rate and the decrease of the bubble rising velocity (UB). Further, adding media in both reactors significantly decreased the UB value. Since media increased flow resistance, resulting in decreased liquid velocity, it can also be the moving bed to capture or block the bubbles from free rising. Therefore, oxygen mass transfer performance was investigated. The oxygen transfer coefficient (KLa) in BCR with solid media addition was enhanced up to 31%–56% compared to a non-addition case, while this enhancement was greater at higher solid loading due to its higher effective surface, resulting in a higher bubble break-up rate compared to the lower loading. In ALR, up to 38.5% enhanced KLa coefficient was archived after adding plastic media over the non-addition case. In conclusion, ring and cylinder media were found to be the most significant for improving KLa value in BCR and ALR, respectively, without extra energy.

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“…The comparison of the bubble column results of Sastaravet et al [20] with the kLa from membrane type A is depicted in Fig. 7.…”

Section: Comparison the Kla Between Hollow Fiber Membrane Contactor Amentioning

confidence: 99%

“…7. Comparison of the kLa between the membrane contactor and the cylindrical bubble column [20] in the different gas superficial velocity.…”

Section: Comparison the Kla Between Hollow Fiber Membrane Contactor Amentioning

confidence: 99%

Study of Aeration and CO2 Absorption Using Filtration Membranes in Terms of Physical Properties and Mass Transfer Parameters

Phanpa¹,

Wongwailikhit²,

Dammee³

et al. 2018

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Hollow fiber membrane contactor is nowadays one of the alternative absorption processes for the conventional bubble column. In this work, the performances of microporous hollow fiber membranes for aeration and CO2 absorption were investigated and compared with a conventional bubble column. The membranes used in this work were adapted from filtration membranes which are significantly cheaper than conventional absorption membranes. The effects of operating variables such as average pore sizes, gas flow rates, liquid flow rates, number of hollow fiber membrane, and concentrations of chemical solution on the gas-liquid absorption rate were determined. For oxygen-water absorption, the overall mass transfer coefficient (kLa), which corresponding to the absorption rate, increased with the increase of membrane porous diameter. The kLa was also enhanced with the increase of the liquid flow rate and the number of membranes while the gas flow rate was rarely influent. For carbon dioxide absorption, the increase in liquid flow rate and the carbon dioxide concentration resulted in higher mass transfer rate. Moreover, adding sodium carbonate in absorbent improved the kLa value up to 2.2 folds, comparing with physical absorption. The comparison between the membrane contractor and a bubble column indicated that the utilization of filtration membranes had more efficiency comparing to bubble column due to its high surface area and adaptability when operating with the same size especially when using lower gas velocity rate.

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Comparative Study of Mass Transfer and Bubble Hydrodynamic Parameters in Bubble Column Reactor: Physical Configurations and Operating Conditions

Cited by 13 publications

References 12 publications

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

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

Relative Effect of Additional Solid Media on Bubble Hydrodynamics in Bubble Column and Airlift Reactors towards Mass Transfer Enhancement

Study of Aeration and CO2 Absorption Using Filtration Membranes in Terms of Physical Properties and Mass Transfer Parameters

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