Mass transfer in a confined plunging liquid jet bubble column

Evans, G. R.; Machniewski, P.

doi:10.1016/s0009-2509(99)00221-3

Cited by 13 publications

(9 citation statements)

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“…At low liquid flow rates as shown in Fig. 3a, the system provided gas (bubble)-liquid dispersion only at the entry region which was highly turbulent with shear, as also found in similar type downflow reactors [11,14,15]. The entry zone (up to 0.25±0.30 m from the top) exhibited a bubble size range of 1±2 mm resulting from the balance of two-phase inlet jet flow and breakup rate of larger bubbles due to the incoming jet.…”

Section: Flow Characteristics In M-dbc Reactorsupporting

confidence: 58%

Operating Characteristics and Performance of a Monolithic Downflow Bubble Column Reactor in Selective Hydrogenation of Butyne‐1,4‐diol

Marvan¹,

Winterbottom

2003

Chem Eng & Technol

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The effects of flow condition, bubble dispersion level, and liquid flow rate on the behavior of a novel monolithic downflow bubble column (M-DBC) were investigated using a reaction model, the palladium-catalyzed hydrogenation of butyne-1,4-diol. The stable and closely packed homogeneous bubble dispersion present in the bulk region of the M-DBC allowed effective introduction of the gas-liquid phase for formation of Taylor flow inside the monolith channels. The condition defined as the minimum level dispersion was required in order to obtain high selectivity towards the intermediate product, cis-2-butene-1,4-diol. Enhanced reaction rates were obtained at increasing the dispersion level and lowering the liquid flow rate. Comparison with the DBC employing 5 % Pd/C powder catalyst and 1 % Pd-on-Raschig-ring revealed a better performance of the M-DBC (1 % Pd loading) with the advantage of smaller reaction volume and intensified reaction rate. As an alternative to conventional three-phase reactors, the M-DBC was so simple due to its inherent characteristic operation and no specially designed device is required.

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Section: Flow Characteristics In M-dbc Reactorsupporting

confidence: 58%

Operating Characteristics and Performance of a Monolithic Downflow Bubble Column Reactor in Selective Hydrogenation of Butyne‐1,4‐diol

Marvan¹,

Winterbottom

2003

Chem Eng & Technol

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“…Moreover, mass transfer in the MZ is typically an order of magnitude higher than for the PFZ, due to the high intensity of mixing and energy dissipation (Mao et al, 1993;Evans and Machniewski, 1999).…”

Section: Theoretical Developmentmentioning

confidence: 99%

“…A bubble will split when the critical Weber number is reached. Evans et al (1992) found that for the CPLJC system, the value of We C was equal to 1.2 and successfully applied Equations [4][5][6] for the prediction of d b,max in the CPLJC. Their system employed a surfactant to inhibit bubble coalescence.…”

Section: Determination Of K L a In The Mixing Zonementioning

confidence: 99%

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Ozone Mass Transfer in the Mixing Zone of a Confined Plunging Liquid Jet Contactor

Jakubowski

Atkinson

Dennis

et al. 2006

Ozone: Science & Engineering

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In a Confined Plunging Liquid Jet Contactor (CPLJC) a jet of liquid is introduced into an enclosed cylindrical column (downcomer) that generates fine gas bubbles that are contacted with the bulk liquid flow. The region where the liquid jet impinges the receiving liquid and expands to the wall of the downcomer is called the Mixing Zone (MZ). In the MZ, the energy of the liquid jet is dissipated by the breakup of the entrained gas into fine bubbles, and the intense recirculation of the two-phase mixture. The study presented here was undertaken to quantify the ozone-water mass transfer performance of the MZ through the determination of the volumetric mass transfer coefficient, k L a (s À1 ), and to produce a model for predicting k L a based on the specific energy dissipation rate. It was found experimentally that k L a in the MZ increased with increasing superficial gas velocity. A maximum experimental k L a value of 0.84 s À1 was achieved which compares well to other contactors used in water treatment. Such a large k L a value combined with the small volume of the reactor, favorable energy requirements and safety features of the system, suggests that the CPLJC provides an attractive alternative to conventional ozone contactors. The relatively large mass transfer rates were found to be a function of the high gas holdup and fine bubble size generated in the MZ, which results in an almost froth-like consistency. A model based on the specific energy dissipation rate of the water jet, E (kg m À1 s À3 ), and MZ bubble size was used to predict k L a in the MZ. Using E, the number average bubble size was predicted which was then used to calculate the liquid phase mass transfer coefficient k L . The bubble size was also used with the predicted mixing zone gas holdup to calculate the specific interfacial area, a (m À1 ), which was then combined with k L to determine a predicted value of k L a. The average deviation between experimental and predicted k L a was 6.2%.

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“…All the reported literature mainly came from the groups in IIT Kharagpur, India (Kundu et al, 1995;Mandal et al, 2003;Majumder et al, 2006), and the one in University of Newcastle, Australia (Evans and Machniewski, 1999;Evans et al, 2001). Though attempts have been made to understand the physics better but complete understanding of hydrodynamics of downflow bubble column is still lacking.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Downflow Bubble Columns: Experiments and Modeling

Upadhyay

Kaim

Roy

2009

J. Chem. Eng. Japan

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In current work, experiments are performed on a laboratory scale downflow bubble column to quantify the effect of operating conditions (gas and liquid flow rates) on gas holdup and its mixing characteristics. Gamma ray densitometry technique is used to find the radial gas holdup profiles in the various sections of column for different operating conditions. Subsequently, residence time distribution (RTD) experiments through conductivity measurements are conducted and the dispersion coefficients are obtained to quantify the mixing behavior. Finally, comparison of experimental results is done against two-fluid Euler-Euler model developed for the downflow bubble column which is studied experimentally.

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Mass transfer in a confined plunging liquid jet bubble column

Cited by 13 publications

References 0 publications

Operating Characteristics and Performance of a Monolithic Downflow Bubble Column Reactor in Selective Hydrogenation of Butyne‐1,4‐diol

Operating Characteristics and Performance of a Monolithic Downflow Bubble Column Reactor in Selective Hydrogenation of Butyne‐1,4‐diol

Ozone Mass Transfer in the Mixing Zone of a Confined Plunging Liquid Jet Contactor

Investigation of Downflow Bubble Columns: Experiments and Modeling

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