Stochastic analysis of bubble and particle motions in a 2-D three-phase reactor.

Kikuchi, Ryuji; Tsutsumi, Atsushi; Yoshida, Kunio

doi:10.1252/jcej.30.202

“…In the transition and churn‐turbulent regimes, the lumped hindering effect of another transport mechanism (‘lifting’ the particle by the bubble via its liquid layer, a larger contraction of cross‐sectional area for particle movement) began to play an important role that resulted in V rel being approximately equal to or lower than U p . These findings are in an agreement with the results of visual and power spectral analysis by Kikuchi et al 30 They observed in bubbly flow that the bubbles exerted a wobbling motion, avoiding any encounters with the tracer particle, whereas in the churn‐turbulent flow, larger coalescing bubbles moved upwards faster and more straightforward. In the churn‐turbulent regime, a mechanism of direct particle–bubble collisions was evident, which hindered the particle settling.…”

Section: Resultssupporting

confidence: 92%

Motion of a magnetic flow follower in two‐phase flow — application to the study of airlift reactor hydrodynamics

Klein

¹

,

Godó

²

,

Teixeira

³

2006

J of Chemical Tech & Biotech

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A low-cost and simple magnetic particle tracer method was adapted to characterize the hydrodynamic behavior of an internal-and an external-loop airlift reactor (ALR). The residence time distribution of three magnetic particles differing in diameter (5.5, 11.0 and 21.2 mm) and with a density very close to that of water was measured in individual reactor sections. The measured data were analyzed and used to determine the velocity of the liquid phase. Validation of the experimental results for liquid velocity was done by means of the data obtained by an independent reference method. Furthermore, analysis of the differences found in the settling velocity of the particle in single-liquid and gas-liquid phases was carried out, using a simplified 3D momentum transfer model. The model considering particle-bubble interaction forces resulting from changes in the liquid velocity field due to bubble motion was able to predict satisfactorily the increase in the particle settling velocity in the homogeneous bubbly regime. The effective drag coefficient in two-phase flow was found to be directly dependent on particle Reynolds number to the power of −2 but independent of gas flow-rate for all particle diameters studied. Based on the experimental and theoretical investigations, the valid exact formulation of the effective buoyancy force necessary for the calculation of the correct particle settling velocity in two-phase flow was done. In addition, recommendations concerning the use of flow-following particles in internal-loop ALRs for liquid velocity measurements are presented.  2006 Society of Chemical IndustryKeywords: multiphase flow; airlift reactors; hydrodynamics; momentum transfer; solid mechanics, flow followerRe p Reynolds number of particle

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“…Local probe signal from optical probes (e.g. Bakshi, Zhong, Jiang, & Fan, 1995), optical transmittance probes (Kikuchi, Tsutsumi, & Yoshida, 1997), temperature probes (Thimmapuram, Rao, & Saxena, 1992), hot lm anemometry (e.g. Magaud, 1999), electrochemical probes (Vial, 2000) can give information of ow regime.…”

Section: Measurement and Analysis Of Signal Uctuationsmentioning

confidence: 99%

Measuring Techniques in Gas—Liquid and Gas—Liquid—Solid Reactors

Boyer¹,

Duquenne²,

Wild³

2003

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This article oers an overview of the instrumentation techniques developed for multiphase ow analysis either in gas/liquid or in gas/liquid/solid reactors. To characterise properly such reactors, experimental data have to be acquired at dierent space scale or time frequency. The existing multiphase ow metering techniques described give information concerning reactor hydrodynamics such as pressure, phases holdups, phases velocities, ow regime, size and shape of dispersed inclusions, axial diusion coecients. The measuring techniques are presented in two groups: the non-intrusive techniques that deliver global, cross-section-averaged or local data, and the intrusive probes that are dedicated to local measurements. Eventually some examples of multiphase instrumentation development are reported (trickle-bed and slurry bubble column at semi-industrial scale) in the renery or petrochemical area.

show abstract

Measuring techniques in gas–liquid and gas–liquid–solid reactors

Boyer¹,

Duquenne

²

,

Wild

³

2002

Chemical Engineering Science

View full text Add to dashboard Cite

This article oers an overview of the instrumentation techniques developed for multiphase ow analysis either in gas/liquid or in gas/liquid/solid reactors. To characterise properly such reactors, experimental data have to be acquired at dierent space scale or time frequency. The existing multiphase ow metering techniques described give information concerning reactor hydrodynamics such as pressure, phases holdups, phases velocities, ow regime, size and shape of dispersed inclusions, axial diusion coecients. The measuring techniques are presented in two groups: the non-intrusive techniques that deliver global, cross-section-averaged or local data, and the intrusive probes that are dedicated to local measurements. Eventually some examples of multiphase instrumentation development are reported (trickle-bed and slurry bubble column at semi-industrial scale) in the renery or petrochemical area.

show abstract

Stochastic analysis of bubble and particle motions in a 2-D three-phase reactor.

Cited by 6 publications

References 11 publications

Motion of a magnetic flow follower in two‐phase flow — application to the study of airlift reactor hydrodynamics

Motion of a magnetic flow follower in two‐phase flow — application to the study of airlift reactor hydrodynamics

Measuring Techniques in Gas—Liquid and Gas—Liquid—Solid Reactors

Measuring techniques in gas–liquid and gas–liquid–solid reactors

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