Enhanced mass transfer in a novel external‐loop airlift reactor with self‐agitated impellers

Lukić, Nataša; Šijački, Ivana M.; Kojić, Predrag; Popović, Sanja; Tekić, Miodrag N.; Petrović, Dragan Lj.

doi:10.1016/j.bej.2016.11.014

Cited by 22 publications

(8 citation statements)

References 44 publications

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“…Plus, Zhiyong Zheng et al [25] improved K L a value by installing helical sieve plate, while Nataša Lj. Lukić [9] added self-agitated impellers for better K L a performance.…”

Section: Discussionmentioning

confidence: 99%

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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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“…Plus, Zhiyong Zheng et al [25] improved K L a value by installing helical sieve plate, while Nataša Lj. Lukić [9] added self-agitated impellers for better K L a performance.…”

Section: Discussionmentioning

confidence: 99%

“…Nikakhtari and Hill [7] developed ALR by inserting nylon mesh packing in the riser, which resulted in a better K L a coefficient compared to an unpacked one. Lukić et al [8,9] also worked on ALR development by installing a self-agitated impeller in the riser to improve its performance.…”

Section: Introductionmentioning

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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“…The concentration of n-butanol was chosen according to the critical concentrations reported by Keitel (9). The experimental procedure for determining surface tensions and surface tension gradients along with the main physical properties of the employed liquid phases can be found in our previous work (10). One of four restriction orifices (70, 50, 30 or 10% free orifice area) was mounted at the top of the downcomer to alter liquid circulation resistance and, consequently, obtain lower liquid recirculation rates for the same superficial gas velocity.…”

Section: Methodsmentioning

confidence: 99%

Influence of the geometry on the riser gas holdup in an external-loop airlift reactor: empirical and neural network modelling

Lj.

Aleksandar

2018

ACTA PERIOD TECHN

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Experimental studies on the effect of geometrical characteristics (restriction orifice free area and sparger configuration) on the riser gas holdup of an external-loop airlift reactor have been conducted in this paper. The impact of the addition of non-coalescing media, such as n-butanol, was also investigated. In general, the decrease in the restriction orifice free area led to a substantial increase (up to 90%) in the riser gas holdup. The addition of n-butanol effected gas holdup to a lesser extent, as it increased the gas holdup in the range of 4-15%, depending on the restriction orifice free area. On the other hand, the impact of the sparger type was observed only at lower gas velocities, for which the sinter plate increased the gas holdup up to 20% in comparison to the single orifice. The paper also presents an empirical correlation for the estimation of the riser gas holdup with an average relative error of 7%. Finally, a neural network model with an average relative error of 2.4% was proposed.

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“…Various pressures were measured during the tests to estimate the power consumption of the aeration. The oxygenation efficiency was compared with that of the available operational units equipped with different sparger types-namely, airlift reactor, bubble column, stirred tank, draft tube stirred reactor [34][35][36][37]. The specific volumetric power consumed during the aeration process was estimated, taking into account the power air supply and mixing power consumption.…”

Section: Comparison To Other Aeration Systemsmentioning

confidence: 99%

Auto-Aspirated DAF Sparger Study on Flow Hydrodynamics, Bubble Generation and Aeration Efficiency

et al. 2020

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A novel auto-aspirated sparger is examined experimentally in a closed-loop reactor (CLR) at lab scale using particle image velocimetry, high-speed camera and oxygen mass transfer rate measurements. State-of-the-art 3D printing technology was utilized to develop the sparger design in stainless steel. An insignificant change in the bubble size distribution was observed along the aerated flow, proving the existence of a low coalescence rate in the constraint domain of the CLR pipeline. The studied sparger created macrobubbles evenly dispersed in space. In pure water, the produced bubble size distribution from 190 to 2500 μm is controlled by liquid flow rate. The bubble size dynamics exhibited a power-law function of water flow rate approaching a stable minimum bubble size, which was attributed to the ratio of the fast-growing energy of the bubble surface tension over the kinetic energy of the stream. Potentially, the stream energy can efficiently disperse higher gas flow rates. The oxygen transfer rate was rapid and depended on the water flow rate. The aeration efficiency below 0.4 kW/m3 was superior to the commonly used aerating apparatuses tested at lab scale. The efficient gas dissolution technology has potential in water treatment and carbon capture processes applications.

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Enhanced mass transfer in a novel external‐loop airlift reactor with self‐agitated impellers

Cited by 22 publications

References 44 publications

Relative Effect of Additional Solid Media 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

Influence of the geometry on the riser gas holdup in an external-loop airlift reactor: empirical and neural network modelling

Auto-Aspirated DAF Sparger Study on Flow Hydrodynamics, Bubble Generation and Aeration Efficiency

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