Axial dispersion in a pulsed plate column

Baird, M. H. I.

doi:10.1002/cjce.5450520608

Cited by 30 publications

(15 citation statements)

References 12 publications

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“…An earlier study by Baird (1974) had examined singlephase axial mixing in a 15 cm diameter pulsed column equipped with a stack of coarse baffles in the form of halfcircular plates. In this case, The ratio EIuf tended to decrease at higher plate spacings and increase at higher operating amplitudes, within the above range.…”

Section: Axial Dispersionmentioning

confidence: 99%

Axial mixing in a 15 cm diameter reciprocating plate bubble column

Baird

Rao

1998

Can J Chem Eng

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Axial dispersion coefficients (E) in the liquid phase have been measured by unsteady tracer response methods in a 15 cm internal diameter reciprocating plate bubble column, using air and water in countercurrent and cocurrent flow. The operating variables studied were amplitude (0.6-1.27 cm) and frequency (0-5 Hz) of reciprocation, and the superficial velocities of the liquid and gas phases and the spacing between plates. Three types of plate were studied; conventional Karr-type plates with perforation diameters 1.43 cm, plates with smaller (0.635 cm) perforations, and single-perforation (doughnut) plates with internal diameter 7 cm. Measured values of E ranged from about 1 cm2/s to a maximum of 116 cm2/s. In general, the plates with 0.635 cm perforations gave the smallest values of E while the largest values of E were obtained with the doughnut plates, due to vortex ring shedding. The single liquid phase data for the three types of plate were approximately consistent with the correlation of Stevens and Baird (1990). The gas-liquid flow results were interpreted in terms of several different hydrodynamic effects.On a mesurC des coefficients de dispersion axiale (E) dans la phase liquide par des mCthodes de rCponse des traceurs en rigime non stationnaire dans une colonne B bulles B plateaux reciproques de 15 cm de diamktre intCrieur, en utilisant I'air et l'eau en Ccoulement ii contrecourant et B cocourant. Les variables de fonctionnement CtudiCes comprennent l'amplitude (0,6-1,27 cm) et la friquence (0-5 Hz) de rtciprociti, ainsi que les vitesses superficielles des phases liquide et gazeuse et I'espacement entre les plateaux. Trois types de plateaux ont Ct C CtudiCs: des plateaux de type Karr classiques avec des diamktres de perforation de 1,43 cm, des plateaux aux perforations plus petites (0,635 cm) et des plateaux h perforation unique (style ccbeignetr) d'un diamktre intkrieur de 7 cm. Les valeurs mesuries de E sont comprises entre environ 1 cm2/s et 116 cm2/s au maximum. En g6nCra1, les plateaux aux perforations de 0,635 cm donnent les valeurs de E les plus petites, tandis que les plus grandes valeurs de E sont obtenues avec les plateaux de style abeigneta, en raison de la nappe turbulente du vortex annulaire. Les donnies de la phase liquide unique pour les trois types de plateaux concordent de manikre approximative avec la corrClation de Stevens et Baird (1990). Les rCsultats de I'6coulement gaz-liquide sont interprCtCs en fonction de plusieurs effets hydrodynamiques.

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Section: Axial Dispersionmentioning

confidence: 99%

Axial mixing in a 15 cm diameter reciprocating plate bubble column

Baird

Rao

1998

Can J Chem Eng

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“…This can be done by a modification of the indicator color change technique which was originally developed by Baird (1974) for measurement of axial mixing.…”

Section: Mass Transfermentioning

confidence: 99%

Mass transfer and pressure drop in a cocurrent reciprocating plate extraction column

Noh

Baird

1984

AIChE Journal

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A 5‐cm‐diameter reciprocating plate extraction column has been operated in cocurrent flow. The pressure drop for water flow, and the local and average mass transfer products for the system acetic acid/kerosene/aqueous sodium hydroxide have been measured. Under well‐agitated conditions, the mass average transfer product is predictable by a model, which is also applicable to data reported earlier by Karr for a 2.54‐cm‐diameter column.

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“…Most of the investigations indicated that axial mixing increased with phase velocities as well as oscillatory motion expressed in terms of a x f with x varying between 1 and 2. Among such investigations is the work of Baird (1974) for single-phase axial…”

Section: Previous Workmentioning

confidence: 99%

Analysis of Axial Mixing in a Gas-Liquid Reciprocating Plate Column

Gomaa

Al‐Taweel

2007

Chemical Engineering Communications

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Axial mixing in the continuous phase in a Landau reciprocating-plate column (LRPC) has been investigated for both single-phase and two-phase gas-liquid flow conditions. A hydrodynamic model is proposed in which axial mixing is described as a process consisting of a backflow through the plate plus longitudinal mixing within the stage. The region in the proximity of the plates is almost perfectly mixed, beyond which there is a low-intensity mixing zone that varies in height and degree of mixing depending on phase velocities as well as the plates design and oscillation velocity. The presence of the dispersed phase affects axial mixing in both the well-and poorly mixed regions of each stage in two opposite ways: it decreases the backflow between the stages due to the hindrance effect caused by the presence of gas bubbles, and it increases the axial dispersion coefficient in the second stage by increasing the turbulence and phase entrainment caused by circulation and bubbles rising. The model adjustable parameters were determined from an experimentally measured dispersion coefficient over a wide range of operating conditions using the transient tracer injection method. The predictions of the model compare favorably with experimental data and can be applied for describing axial mixing in the continuous phase in an LRPC with AE14% accuracy.

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Axial dispersion in a pulsed plate column

Cited by 30 publications

References 12 publications

Axial mixing in a 15 cm diameter reciprocating plate bubble column

Axial mixing in a 15 cm diameter reciprocating plate bubble column

Mass transfer and pressure drop in a cocurrent reciprocating plate extraction column

Analysis of Axial Mixing in a Gas-Liquid Reciprocating Plate Column

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