Gas-liquid mass transfer in cyclohexane oxidation process using gas-inducing and surface-aeration agitated reactors

Tekie, Zeru; Li, Jianjun; Morsi, Badie I.; Chang, Min-Yan

doi:10.1016/s0009-2509(96)00502-7

Cited by 33 publications

(24 citation statements)

References 27 publications

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“…The experimental setup used in this study, schematically shown in Figure 1, is similar to that employed by Tekie et al (1997a) and Fillion and Morsi (2000). It consists of a 4-liter ZipperClave reactor (0.1247-m ID), which is equipped with two sight-windows (Jerguson windows), four symmetrically located baffles, a cooling coil, a specially designed heating jacket, a thermo-well and an agitator with a six flat blades impeller and a hollow shaft (0.01-m OD).…”

Section: Methodsmentioning

confidence: 99%

Hydrodynamic and Mass Transfer Parameters in Agitated Reactors Part I: Critical Mixing Speed, Induced Gas Flow Rate, and Wavy Surface in SARs and GIRs

Lemoine¹,

Fillion²,

Morsi³

2004

International Journal of Chemical Reactor Engineering

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The critical mixing speed for gas entrainment (NCRE), for gas induction (NCRI), induced gas flow rate (QGI) as well as the wavy gas-liquid interfacial area (aWave) of N2 and air were measured in pure toluene and three mixtures of organic liquids (toluene-benzoic acid-benzaldehyde mixtures) under wide ranges of temperatures, T (300-453K), pressures, P (1-15 bar), mixing speeds, N (13.3-23.3Hz) and liquid heights, H (0.171-0.268m) using a 4-liter, see-through agitated autoclave operating as a surface-aeration reactor (SAR) and gas-inducing reactor (GIR).NCRE and NCRI as well as aWave were estimated by analyzing the videos taken with an on-line high-speed Phantom camera through the reactor's Jerguson windows. In the GIR, QGI was determined using a highly sensitive Coriolis mass flow meter. The Central Composite Statistical Design and analysis technique was used to study the effect of operating conditions on these hydrodynamic parameters.NCRE and NCRI appeared to increase with liquid height and decrease with temperature, whereas, the pressure and gas nature did not significantly affect both parameters. The liquid physicochemical properties were found to strongly affect NCRE and NCRI, and QGI. Increasing mixing speed or decreasing liquid height increased QGI. Increasing temperature or decreasing liquid viscosity initially increased and then decreased QGI. Increasing pressure or gas density on the other hand decreased QGI. Increasing mixing speed and temperature or decreasing liquid height significantly enhanced aWave, as compared to the flat liquid surface. At high pressures, however, lower values of aWave were obtained. Empirical and statistical correlations were also developed to accurately predict NCRE, NCRI, Brought to you by | University of North Dakota Authenticated Download Date | 5/29/15 6:27 AM QGI and aWave.

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Section: Methodsmentioning

confidence: 99%

Hydrodynamic and Mass Transfer Parameters in Agitated Reactors Part I: Critical Mixing Speed, Induced Gas Flow Rate, and Wavy Surface in SARs and GIRs

Lemoine¹,

Fillion²,

Morsi³

2004

International Journal of Chemical Reactor Engineering

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“…Atypical trends have, however, been pinpointed for the k L a-pressure relationship for some particular organic liquids and temperatures in flat-interface vessels where, in principle, a is only geometry-dependent (Chang et al, 1991;Morsi, 1991a,b, 1992;Mizan et al, 1994;Koneripalli et al, 1994). The different trends of k L a dependencies were attributed to possible variation of k L with pressuredependent liquid diffusion coefficient, liquid viscosity, and surface tension (Tekie et al, 1997). Nevertheless, as the mass-transfer coefficient k L was not measured directly and independently, there is no clear evidence in favor of a k L depending on pressure.…”

Section: Introductionmentioning

confidence: 99%

Gas−Liquid Interfacial Mass Transfer in Trickle-Bed Reactors at Elevated Pressures

Larachi

Cassanello

Laurent

1998

Ind. Eng. Chem. Res.

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A phenomenological description and a semiempirical two-zone model are proposed for the gasliquid interfacial areas and the volumetric liquid-side mass-transfer coefficients in cocurrent downflow trickle-bed reactors operated at elevated pressure. Gas-liquid interfacial areas, a, and volumetric liquid-side mass-transfer coefficients, k L a, are measured in the trickle flow regime at high nitrogen pressure (0.3-3.2 MPa). Use is made of diethanolamine carbamation in aqueous viscous and organic model solutions in which fast and slow absorptions of carbon dioxide occur. In order to extract genuine mass-transfer parameters, a rigorous thermodynamic model is established to account for liquid and gas nonidealities. The influence of pressure, gas and liquid superficial velocities, liquid viscosity, and packing size on the gas-liquid interfacial mass transfer is examined. At constant gas and liquid superficial velocities, increasing the reactor pressure improves the gas-liquid interfacial mass transfer at the expense of increased two-phase pressure drop and gas holdup. At high pressure, the gas-liquid flow may be viewed as a two-zone flow pattern: (i) a liquid-free gas continuous phase which delineates a macroscopic gas-liquid interface (ii) and a gas-liquid film emulsion comprised of tiny bubbles which form in the films and delineate a microscopic gas-liquid interface. Taylor's theory of fluid-fluid sheared emulsions is used to quantify the microscopic interface via the effect of pressure on the size of bubbles in the trickling film. A bubble Sauter diameter is related to viscous shear stress and surface tension force, the two competing forces that determine bubble size. The model is also extended to estimate volumetric gas-liquid mass-transfer coefficients under high-pressure conditions.

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“…Unfortunately, despite the fact that these investigators recognized the importance of the kinetics and gasliquid mass transfer, most of them, except Suresh et al (1988b), either neglected the effect of mass transfer or used predictions from literature correlations developed for an air-water system under ambient conditions. This is not surprising, since available literature data on mass transfer in liquid-phase cyclohexane oxidation process are actually scarce (Tekie et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

“…For an oxygen-cyclohexane system, reaction free mass transfer parameters were measured within the induction period (Suresh et al, 1988c;Tekie et al, 1997) which lasted about 20-30 min depending on the rate of mass transfer and temperature used. The original liquid volume in the reactor was varied to ensure the desired liquid level as set by the experimental design.…”

mentioning

confidence: 99%

Mass Transfer Parameters of O₂ and N₂ in Cyclohexane under Elevated Pressures and Temperatures: A Statistical Approach

Tekie

Morsi

1997

Ind. Eng. Chem. Res.

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The solubility, volumetric mass transfer coefficient, gas−liquid interfacial area, mass transfer coefficient, gas holdup, and bubble Sauter mean diameter for O2 and N2 in liquid cyclohexane were obtained in 4-L gas-inducing and surface-aerated agitated reactors. The modified Peng−Robinson equation of state and the transient gas absorption and photographic techniques were employed. The experiments were statistically designed and the results were statistically correlated with a 95% confidence level. The solubilities for O2 and N2 showed an increase with pressure and temperature, and Henry's law adequately modeled the values. All mass transfer parameters obtained were found to be higher in the gas-inducing than those in the surface-aerated reactor. Mixing speed and liquid height significantly affected the volumetric mass transfer coefficients and gas holdup in both reactors. The pressure and temperature slightly affected the volumetric mass transfer coefficients whereas the bubbles Sauter mean diameter for both gases remained constant at about 0.76 mm.

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Gas-liquid mass transfer in cyclohexane oxidation process using gas-inducing and surface-aeration agitated reactors

Cited by 33 publications

References 27 publications

Hydrodynamic and Mass Transfer Parameters in Agitated Reactors Part I: Critical Mixing Speed, Induced Gas Flow Rate, and Wavy Surface in SARs and GIRs

Hydrodynamic and Mass Transfer Parameters in Agitated Reactors Part I: Critical Mixing Speed, Induced Gas Flow Rate, and Wavy Surface in SARs and GIRs

Gas−Liquid Interfacial Mass Transfer in Trickle-Bed Reactors at Elevated Pressures

Mass Transfer Parameters of O₂ and N₂ in Cyclohexane under Elevated Pressures and Temperatures: A Statistical Approach

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Gas-liquid mass transfer in cyclohexane oxidation process using gas-inducing and surface-aeration agitated reactors

Cited by 33 publications

References 27 publications

Hydrodynamic and Mass Transfer Parameters in Agitated Reactors Part I: Critical Mixing Speed, Induced Gas Flow Rate, and Wavy Surface in SARs and GIRs

Hydrodynamic and Mass Transfer Parameters in Agitated Reactors Part I: Critical Mixing Speed, Induced Gas Flow Rate, and Wavy Surface in SARs and GIRs

Gas−Liquid Interfacial Mass Transfer in Trickle-Bed Reactors at Elevated Pressures

Mass Transfer Parameters of O2 and N2 in Cyclohexane under Elevated Pressures and Temperatures: A Statistical Approach

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Mass Transfer Parameters of O₂ and N₂ in Cyclohexane under Elevated Pressures and Temperatures: A Statistical Approach