Gas entrainment and holdup characteristics in a modified gas–liquid–solid down flow three-phase contactor

Sivaiah, Mekala; Parmar, Rajeev; Majumder, Subrata Kumar

doi:10.1016/j.powtec.2011.10.062

Cited by 11 publications

(5 citation statements)

References 27 publications

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“…A competing hypothesis was put forth that a gas‐continuous headspace exists from which gas is pulled downward alongside each micro‐jet into annular filaments surrounding each micro‐jet, subsequently these filaments eventually break apart into microbubbles. This sequence of events is the same as hypothesized in an impinging‐jet reactor or ejector reactor . However, our γ ‐beam measurements in Table confirm that, for most operating conditions, no gas‐continuous headspace layer exists below the pore plate.…”

Section: Resultssupporting

confidence: 80%

“…This sequence of events is the same as hypothesized in an impinging-jet reactor or ejector reactor. [55][56][57][58][59][60][61] However, our γ-beam measurements in Table 6 confirm that, for most operating conditions, no gas-continuous headspace layer exists below the pore plate. Only at very high gas injection rate does a gas layer develop.…”

Section: Spatial Distributions Of Gas Fraction and Bubble Diametermentioning

confidence: 74%

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A micro‐jet array for economic intensification of gas transfer in bioreactors

Turney

Ansari

Kalaga

et al. 2018

Biotechnology Progress

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Bioreactors are of interest for gas‐to‐liquid conversion of stranded or waste industrial gases, such as CO, CH4, or syngas. Process economics requires reduction of bioreactor cost and size while maintaining intense production via rapid delivery of gases to the liquid phase (i.e., high kLa). Here, we show a novel bioreactor design that outperforms all known technology in terms of gas transfer energy efficiency (kLa per power density) while operating at high kLa (i.e., near 0.8 s−1). The reactor design uses a micro‐jet array to break feedstock gas into a downward microbubble flow. Hydrodynamic and surfactant measurements show the reactor's advanced performance arises from its bubble breakage mechanism, which limits fluid shear to a thin plane located at an optimal location for bubble breakage. Power dissipation and kL are shown to scale with micro‐jet diameter rather than reactor diameter, and the micro‐jet array achieves improved performance compared to classical impinging‐jets, ejector, or U‐loop reactors. The hydrodynamic mechanism by which the micro‐jets break bubbles apart is shown to be shearing the bubbles into filaments then fragmentation by surface tension rather than “cutting in half” of bubbles. Guided by these hydrodynamic insights, strategies for industrial design are given. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2710, 2019

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Section: Resultssupporting

confidence: 80%

Section: Spatial Distributions Of Gas Fraction and Bubble Diametermentioning

confidence: 74%

A micro‐jet array for economic intensification of gas transfer in bioreactors

Turney

Ansari

Kalaga

et al. 2018

Biotechnology Progress

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“…Details of the operational procedure are provided elsewhere. 28 2.2. Physical Properties of the System.…”

Section: Methodsmentioning

confidence: 99%

“…The ranges of variables covered in the present study are listed in Table . Details of the operational procedure are provided elsewhere …”

Section: Methodsmentioning

confidence: 99%

Mass Transfer and Mixing in an Ejector-Induced Downflow Slurry Bubble Column

Sivaiah

Majumder

2013

Ind. Eng. Chem. Res.

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The downflow slurry bubble column reactor is gaining importance as a simple and inexpensive means of achieving efficient multiphase contact and mass-transfer operations. Knowledge about the effects of solids on gas–liquid–solid systems is minimal in the literature. In the present work, the effect of the presence of solids on the mass-transfer characteristics for gas–liquid–solid system is experimentally investigated in a downflow slurry bubble column with an internal diameter of 0.05 m. The mass-transfer coefficient was evaluated using the electroreduction of ferricyanide ions as the model reaction. The effects of superficial slurry velocity, gas velocity, slurry viscosity, and gas holdup on the mass-transfer coefficient were analyzed. The experimental results showed that the mass-transfer coefficient in the column is influenced more by the superficial slurry velocity than the superficial gas velocity. In this work, the mass-transfer efficiency in the gas–liquid–solid downflow bubble column reactor was analyzed for different concentrations of the slurry (0.1–1.0 wt %) and different sizes of the particles (2.21–96.0 μm). Empirical correlations were developed for the downflow slurry system with the different variables to interpret the mass-transfer phenomena. The developed correlation for mass-transfer efficiency as a function of quality of mixedness was also interpreted by the information entropy theory. The present analysis on mass-transfer characteristics and models for predicting the mass-transfer coefficient can provide insight into a further understanding of multiphase reactors in industrial applications.

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“…Current research on the gas and liquid entrainment mainly focused on the rectification, fluid mechanics, froth flotation. and other relevant fields . Krishna et al .…”

Section: Introductionmentioning

confidence: 99%

Study on droplet entrainment in the composite scrubbing–cooling chamber

Wang

Yan

Guo

et al. 2017

Asia-Pacific J Chem Eng

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A cold model experimental device was established for studying droplet entrainment in the composite scrubbing-cooling chamber. The effect of the superficial gas velocity, the initial liquid flow velocity of the nozzle, and the radial position of nozzles on droplet entrainment was investigated. The experimental results show that the droplet entrainment increases with the increase of the superficial gas velocity and the flow rate of falling film, but its profile is quite mean in the radial direction in the chamber. The droplet entrainment decreases by about 40% when the number of nozzles increases from two to four. Increasing the nozzle number can make the droplet well distributed and reduce droplet entrainment. Based on the experiment data, an empirical correlation for droplet entrainment fraction is also obtained, as E ∝ Re 1.92 ·We 0.52 . The optimization study for the structure of the scrubbing-cooling chamber can provide some guidance for the industrial application.

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Gas entrainment and holdup characteristics in a modified gas–liquid–solid down flow three-phase contactor

Cited by 11 publications

References 27 publications

A micro‐jet array for economic intensification of gas transfer in bioreactors

A micro‐jet array for economic intensification of gas transfer in bioreactors

Mass Transfer and Mixing in an Ejector-Induced Downflow Slurry Bubble Column

Study on droplet entrainment in the composite scrubbing–cooling chamber

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