Experimental study of bubbly swirling flow in a vertical tube using ultrasonic velocity profiler (UVP) and wire mesh sensor (WMS)

Hamdani, Ari; Ihara, Takeshi; Tsuzuki, Nobuyoshi; Kikura, Hiroshige

doi:10.1007/s12206-016-0801-6

Cited by 11 publications

(4 citation statements)

References 21 publications

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“…Although a helical swirl element is usually used as a static mixer, in the case of gas-liquid flows where the density difference among those two phases are quite large, the helical swirl element can also act as a separator. This fact can be concluded from the experimental studies in References [5,14]. They used a single helical swirl element and found that the gas can be separated downwards of the element.…”

Section: Introductionmentioning

confidence: 90%

Comparison of Gas–Liquid Flow Characteristics in Geometrically Different Swirl Generating Devices

et al. 2019

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The gas–liquid flow characteristics for blade, single, and the double-helical swirl elements were numerically investigated and compared in this work. The Euler–Euler model assuming bi-modal bubble size distributions was used. The experiment, conducted in a vertical pipe equipped with a static blade swirl element, was used as the basis for the computational fluid dynamics (CFD) simulations. In the experiment, high-resolution gamma-ray computed tomography (HireCT) was used to measure the gas volume fractions at several planes within the blade swirl element. The resulting calculated profiles of the pressure, liquid and gas velocities as well as the gas fraction showed a large influence of the swirl elements’ geometry. The evolution and characteristics of the calculated gas–liquid phase distributions in different measurement planes were found to be unique for each type of swirl element. A single gas core in the center of the pipe was observed from the simulation of the blade element, while multiple cores were observed from the simulations of the single and double helix elements. The cross-sectional gas distribution downstream of the single and double helical elements changed drastically within a relatively short distance downstream of the elements. In contrast, the single gas core downstream of the blade element was more stable.

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Section: Introductionmentioning

confidence: 90%

Comparison of Gas–Liquid Flow Characteristics in Geometrically Different Swirl Generating Devices

et al. 2019

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“…In the case of the recycle pan, this could be achieved by increasing liquid residence time and/or promoting bubble coalescence to produce larger bubbles that disengage faster. Hamdani et al 29 showed that twisted tape inserts, which induce swirling flow, could enhance bubble coalescence, albeit with air−water at atmospheric pressure. Enhancing bubble coalescence is certainly a greater challenge operating at high pressure with surface-active agents, where the extra energy input could potentially further reduce the bubble sizealthough similar solutions have been proposed for gas− liquid separation by Chan and Colvert.…”

Section: Resultsmentioning

confidence: 99%

Fluid Dynamics Modeling of a Commercial Ebullated Bed Hydroprocessor

Mach

Donaldson

Haelssig

et al. 2020

Ind. Eng. Chem. Res.

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A new multiphase fluid dynamics model for a commercial ebullated bed hydroprocessor was developed. The impact of the gas–liquid distribution system is now explicitly included through new submodels for bubble size distribution and drag coefficients. The size distribution submodel is coupled with the existing gas–liquid separation submodel to better predict recycled gas and liquid flow rates. Either the mass of the catalyst inventory or recycle pump curve can be specified as inputs to converge the model; the former is not always well known during operation in which case the latter can be used after making a few assumptions. A sensitivity analysis was performed to study the impact of fresh treat gas velocity, catalyst mass, phase properties, and reactor internals on recycled gas and liquid flow rates, bubble size distribution, and bed liquid holdup. A 0.2 mm shift in bubble size distribution toward larger sizes was found to significantly increase bed liquid holdup, suggesting that distributor modification/redesign could help improve the capacity of the hydroprocessor.

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“…However, mixing of liquid and gas which have a large density difference is a challenging process. The studies of gas-liquid mixing inside the static mixer either experimental or numerical is still limited [3][4][5] As pointed out by [4] [6], the static mixer in some conditions may act as a separator instead of a mixer as shown in the experiment of [4] [7] which both using a helical static mixer inside a pipe. Using advance measurement technique of ultrafast electron beam X-ray tomography [4] observed that the centrifugal force generated by the static mixer element leads to the formation of a swirling flow where the gas is accumulated towards the center of the pipe while the liquid towards the pipe wall.…”

Section: Introductionmentioning

confidence: 99%

Mixing Characteristics Of Gas-Liquid Flow In A Static Mixer: A Numerical Study

Putra

2020

Angkasa

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Mixing characteristics of gas-liquid co-current upward flow inside a vertical pipe equipped with a helical static mixer element were numerically investigated. The results from computational fluid dynamics (CFD) simulations with Euler-Euler model of three different length to diameter ratio (L/D) of the static mixer elements were compared. All simulated static mixers provide a better mixing condition in the comparison with the one without a static element. The sudden increase of rotational strength indicated by the liquid velocity curl was observed once the gas-liquid flows enter the static-mixer element zone. The smallest L/D static mixer provides the highest liquid velocity curl in the smallest axial distance providing the most effective mixing process among the tested elements. The best mixing characteristics shown by radial gas distribution was achieved with the static mixer with a smallest L/D.

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Experimental study of bubbly swirling flow in a vertical tube using ultrasonic velocity profiler (UVP) and wire mesh sensor (WMS)

Cited by 11 publications

References 21 publications

Comparison of Gas–Liquid Flow Characteristics in Geometrically Different Swirl Generating Devices

Comparison of Gas–Liquid Flow Characteristics in Geometrically Different Swirl Generating Devices

Fluid Dynamics Modeling of a Commercial Ebullated Bed Hydroprocessor

Mixing Characteristics Of Gas-Liquid Flow In A Static Mixer: A Numerical Study

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