Flooding and axial dispersion in reciprocating plate extraction columns

Hafez, M. M.; Baird, M. H. I.; Nirdosh, I.

doi:10.1002/cjce.5450570205

Cited by 53 publications

(43 citation statements)

References 15 publications

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“…This trend which was also noted by Hafez et al (1979) and by Karr et al (1987) is due to the observed tendency of the water flow to distribute poorly across the column (fingering). Distribution is improved by moderate agitation; at the highest agitation levels, E is approximately proportional to uh and the relationship is represented approximately by Equation…”

Section: Single Phase (Liquid) Flowmentioning

confidence: 60%

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: Single Phase (Liquid) Flowmentioning

confidence: 60%

Axial mixing in a 15 cm diameter reciprocating plate bubble column

Baird

Rao

1998

Can J Chem Eng

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“…G. Gomaa and A. M. Al Taweel dispersion in a pulsed column equipped with plates similar to those used in a KRPC, in which the axial dispersion coefficient was found to increase with a 2 f , and that of Kim and Baird (1976) in a 0.05 m diameter KRPC, where a similar relation was noted in which E increased with a 1:8 f . The work of Hafez et al (1979) and Baird and Rama Rao (1988) for axial mixing in a 0.15 m and 0.05 m diameter KRPC, respectively, showed a somewhat different trend in which axial dispersion varied linearly with af . Other investigations using different types of columns also showed an increase in dispersion coefficient with the oscillation frequency and amplitude but with different powers (Parthasarathy et al, 1984;Rama Rao et al, 1986).…”

mentioning

confidence: 87%

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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“…It optimizes two parameters, the MRT and Pe. This model calculates the RTD response of a system to an arbitrary pulse of tracer by convoluting the input function with impulse response of the model [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. It uses the least square curve fitting method to fit the model RTD function (Eq.…”

Section: Epj Web Of Conferencesmentioning

confidence: 99%

“…Effect of various geometrical and operating parameters on the axial mixing of continuous phase has been reported in these investigations [5][6][7][8][9]. Most of these studies have been carried out using visual method after injecting a dye tracer or a conventional method by injecting a non-radioactive tracer and measurements were made by a conductivity probe.…”

Section: Introductionmentioning

confidence: 99%

Radiotracer investigations to study the hydrodynamic characteristics of continuous phase in a pulsed sieve plate extraction column

Din

Khan

Chughtai

et al. 2013

EPJ Web of Conferences

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Abstract. The present investigations are focused to study the hydrodynamic characteristics of continuous phase in a pulsed sieve plate extraction column using 68 Ga in the form of gallium chloride from an industrial radionuclide generator ( 68 Ge/ 68 Ga). Labeling of water with the subject radiotracer in water-kerosene environment was evaluated. Experiments for Residence Time Distribution (RTD) analysis were carried out for a range of dispersed phase superficial velocities in a liquid-liquid extraction pulsed sieve plate column operating in the emulsion regime with water as continuous and kerosene as dispersed phase. Axial Dispersion Model (ADM) was used to simulate the hydrodynamic characteristics of continuous phase. It has been observed that the axial mixing in the continuous phase decreases and slip velocity increases with increase in superficial velocity of dispersed phase while the holdup of continuous phase was found to decrease with increase in superficial velocity of dispersed phase. ADM with open-open boundary condition was found to be a suitable model for the subject system.

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Flooding and axial dispersion in reciprocating plate extraction columns

Cited by 53 publications

References 15 publications

Axial mixing in a 15 cm diameter reciprocating plate bubble column

Axial mixing in a 15 cm diameter reciprocating plate bubble column

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

Radiotracer investigations to study the hydrodynamic characteristics of continuous phase in a pulsed sieve plate extraction column

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