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  • 1
    Electronic Resource
    Electronic Resource
    Diffusion coefficients of several aqueous alkanolamine solutions (1993)
    s.l. : American Chemical Society
    Journal of chemical & engineering data 38 (1993), S. 475-480 
    Details
    ISSN: 1520-5134
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/je00011a037
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  • 2
    Electronic Resource
    Electronic Resource
    Physical absorption of CO2 and propene into toluene/water emulsions (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1629-1638 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The physical absorption of CO2 and propene into toluene/water emulsions is studied in a stirred cell and laminar film absorber. Experimentally observed masstransfer rates are compared to an absorption model, based on Higbie's penetration theory describing physical gas absorption into an emulsion. For all absorption experiments in a stirred cell absorber (toluene fractions and stirring rates), experimentally observed mass-transfer rates are considerably higher than the rates predicted by the absorption model. Moreover, the absorption rate decreases with increasing stirring rate, whereas no influence of the stirring rate is predicted by the absorption model. In contradiction to the absorption experiments in a stirred cell absorber, the observed mass-transfer rates in the laminar film absorber agree with the model simulations. Probable existence of a very thin toluene layer is observed on top of the emulsion for the stirred cell experiments, likely due to minor phase separation. Since in the laminar film absorber gas-liquid interface and the gravity force are parallel, this phenomenon does not probably occur significantly for absorption experiments in this absorber. The observed mass-transfer phenomena can be explained, at least qualitatively, from the occurrence of a thin toluene layer.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690401005
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  • 3
    Electronic Resource
    Electronic Resource
    Novel method for noncontact measurement of particle temperatures (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 773-782 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A nonintrusive temperature measurement technique is developed for noncontact measurement of the temperature of single particles with 〈 200 μm dia. It is based on the temperature dependence of the fluorescence spectrum resulting from irradiation of a certain phosphor mixture with UV light by applying a mixture of two phosphors with fluorescence colors (blue and green) and a color shift from green to blue (with temperature increase from 20 to 280°C). An experimental setup is described for temperature measurement of particles based on the fluorescence color, together with the calibration of this system. The fluoroptic technique is applied to measure the temperature decrease of hot particles flowing down a cold chute. The measurements agree very well with thermocouple measurements. This novel technique can be applied to nonintrusive measurement of particle temperatures in (dense) multiparticle systems as encountered in packed and fluidized beds.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690410404
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetics of COS with primary and secondary amines in aqueous solutions (1992)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 38 (1992), S. 244-250 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The reaction between COS and aqueous solutions of primary and secondary amines has been studied by means of the stirred cell technique. Kinetic experiments at temperatures 283 to 333 K were carried out with MEA, DGA, DEA, DIPA, MMEA, AMP, and MOR. All kinetic experiments could be described by a zwitterion reaction mechanism similar to the mechanism proposed by Caplow (1968) for the reaction between CO2 and secondary amines: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} COS + R_2 NH \leftrightarrow R_2 NH^ + COS^ - \\ R_2 NH^ + COS^ - + B \leftrightarrow R_2 NCOS^ - + BH^ + \\ \end{array} $$\end{document}Analysis of concentrated amine solutions at high COS concentrations by various analytical techniques confirmed the conclusions from the kinetic experiments. For all amines except for MEA, the overall reaction rate was found to be determined entirely by the zwitterion deprotonation rate.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690380210
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  • 5
    Electronic Resource
    Electronic Resource
    Letters to the Editor (1993)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 39 (1993), S. 724-726 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690390426
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  • 6
    Electronic Resource
    Electronic Resource
    Kinetics of hydrogen absorption and desorption in LaNi5-xAlx slurries (1993)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 39 (1993), S. 1444-1454 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics of hydrogen absorption and desorption in LaNi4.8Al0.2,LaNi4.9Al0.1 and LaNi5, suspended in cyclohexane and LaNi5 in ethanol have been investigated. The absorption process can be described in terms of mass transfer and reaction resistances in series. The rate-limiting steps for this process are dissolution of hydrogen in the solvent and the reaction of hydrogen with the metal alloy. Over a broad range of hydrogen loadings, the reaction of hydrogen with the metal follows the rate equation:\documentclass{article}\pagestyle{empty}\begin{document}$$ R_{{\rm abs}} = k_a a_s \left({C_{{\rm H}_{2,S}} - C_{{\rm eq,}a}} \right) $$\end{document}This type of kinetic equation indicates that during hydride formation in a slurry a surface process is the rate-determining step, which was confirmed by the observed influence of the solvent. Desorption of hydrogen can be described best with a shrinking core relation:\documentclass{article}\pagestyle{empty}\begin{document}$$ 1 - \left({1 - X} \right)^{1/3} = k_d ln\left({\frac{{P_{eq,d}}}{{P_{H_2}}}} \right)t $$\end{document}The phase transformation at the β/α boundary appears to be the rate-determining step. Alloys with higher aluminum contents produce a lower reaction rate constant.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690390904
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  • 7
    Electronic Resource
    Electronic Resource
    Kinetics of Carbon Dioxide with tertiary Amines in aqueous solution (1990)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 36 (1990), S. 1633-1640 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The reaction of CO2 with TEA, DMMEA, and DEMEA has been studied at 293, 303, 318 and 333 K. All the kinetic experiments were carried out in a stirred cell reactor operated with a flat, smooth and horizontal gas-liquid interface. A numerical method, which describes mass transfer accompanied by reversible chemical reactions, has been applied to infer rate constants from the experimental data. It is argued that the contribution of the CO2 reaction with OH- to the observed reaction rate may have been overstimated in most literature on tertiary amine kinetics as serious depletion of OH- toward the gas-liquid interface usually occurs.For all the amines studied, the reaction order in amine was found to be about one for each temperature investigated. This is in good agreement with the base catalysis mechanism proposed by Donaldson and Nguyen (1980). All kinetic data could be summarized reasonably well in one Brønsted relationship.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690361103
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  • 8
    Electronic Resource
    Electronic Resource
    High-temperature membrane reactor for catalytic gas-solid reactions (1992)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 38 (1992), S. 887-900 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model, based on the dusty-gas model extended with surface diffusion, is presented that describes mass transport owing to molecular diffusion and viscous flow, as well as an instantaneous reversible reaction inside a membrane reactor. The reactants are fed to opposite sides of the membrane, considering masstransfer resistances in the gas phase outside the membrane. The Claus reaction is chosen as a model reaction to study this membrane reactor.The model is used to validate a previously presented simplified model. The simplified model predicts correct molar fluxes when it is very dilute and can therefore be considered a pseudo-binary system. Occurrence of a maximum or a minimum in the pressure profile inside the membrane, in the absence of an overall pressure difference over the membrane, depends not only on the stoichiometry of the reaction but on mobilities of the different species.The Claus reaction is used to verify experimentally the transport model for a nonpermselective membrane reactor with a mean pore diameter of 350 nm. At 493 K and 542 K, molar fluxes experimentally determined are 10 to 20% lower than those predicted by the transport model. Conversions measured at pressures of 220 kPa and 500 kPa demonstrate that surface diffusion occurs as a transport mechanism despite the large pore diameter of the membrane. In the presence of a pressure difference over the membrane, there is a reasonable agreement between experimentally determined molar fluxes and those calculated by the transport model.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690380610
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  • 9
    Electronic Resource
    Electronic Resource
    Numerical calculation of wall-to-bed heat-transfer coefficients in gas-fluidized beds (1992)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 38 (1992), S. 1079-1091 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A computer model for a hot gas-fluidized bed has been developed. The theoretical description is based on a two-fluid model (TFM) approach in which both phases are considered to be continuous and fully interpenetrating. Local wall-to-bed heat-transfer coefficients have been calculated by the simultaneous solution of the TFM conservation of mass, momentum and thermal energy equations. Preliminary calculations suggest that the experimentally observed large wall-to-bed heat-transfer coefficients, frequently reported in literature, can be computed from the present hydrodynamic model with no turbulence. This implies that there is no need to explain these high transfer rates by additional heat transport mechanisms (by turbulence).The calculations clearly show the enhancement of the wall-to-bed heat-transfer process due to the bubble-induced bed-material refreshment along the heated wall. By providing detailed information on the local behavior of the wall-to-bed heat-transfer coefficients, the model distinguishes itself advantageously from previous theoretical models. Due to the vigorous solids circulation in the bubble wake, the local wall-to-bed heat-transfer coefficient is relatively large in the wake of the bubbles rising along a heated wall.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690380711
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  • 10
    Electronic Resource
    Electronic Resource
    Hydrodynamic modeling of gas/particle flows in riser reactors (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1569-1582 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Complex hydrodynamic behavior of circulating fluidized beds makes their scale-up very complicated. In particular, large-scale lateral solids segregation causes a complex two-phase flow pattern which influences significantly their performance. Lateral solids segregation has been attributed to direct collisional interactions between particles as well as to interaction between gas-phase eddies and dispersed particles. However, these phenomena have not been investigated thoroughly.This article discusses an advanced 2-D hydrodynamic model developed for circulating fluidized beds based on the two-fluid concept. Because theory to model the interaction between gas-phase eddies and dispersed particles is not available, turbulence was modeled on a macroscopic scale using a modified Prandtl mixing length model. To model the influence of direct particle-particle collisions the kinetic theory for granular flow was applied based on the Chapman-Enskog theory of dense gases. For model validation purposes, a cold flow circulating fluidized bed was employed in which sand was transported with air as fluidizing agent. The column is equipped with pressure transducers to measure the axial pressure profile and with a reflective optical fiber probe to measure the local solids concentration and axial solids velocity. Theoretically calculated solids concentration and axial solids velocity agree satisfactorily with experiment, especially when one realizes that the model contains no adjustable parameters. In general, however, the model slightly underpredicted the experimentally observed lateral solids segregation and yielded a more peaked velocity profile compared to its experimental counterpart.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420608
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