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A Combined numerical and experimental study of hydrodynamics for an air-water external loop airlift reactor / Law, Deify in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 08 p. Titre : A Combined numerical and experimental study of hydrodynamics for an air-water external loop airlift reactor Type de document : texte imprimé Auteurs : Law, Deify, Auteur ; Jones, Samuel T., Auteur ; Heindel, Theodore J., Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Airlift  reactor  Bubbly  flows  Computational  fluid  dynamics  Gas  holdup  Hydrodynamics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The external loop airlift reactor (ELALR) is a modified bubble column reactor that is composed of two vertical columns that are interconnected with two horizontal tubes and is often preferred over traditional bubble column reactors because they can operate over a wider range of conditions. In the present work, the gas-liquid flow dynamics in an ELALR was simulated using an Eulerian–Eulerian ensemble-averaging method in two-dimensional (2D) and three-dimensional (3D) coordinate systems. The computational fluid dynamics (CFD) simulations were compared to experimental measurements from a 10.2 cm diameter ELALR for superficial gas velocities ranging from 1 cm/s to 20 cm/s. The effect of specifying a mean bubble diameter to represent the gas phase in the CFD modeling was investigated, and 2D and 3D simulations were found to be in good agreement with the experimental data. The ELALR flow regimes were compared for the reactor operating in bubble column, closed vent, and open vent modes, and the 2D simulations qualitatively predicted the behavior of bubble growth in the downcomer. However, it was found that 3D simulations were necessary to capture the physics of the ELALR for gas holdup, bulk density differences, and riser superficial liquid velocity. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] A Combined numerical and experimental study of hydrodynamics for an air-water external loop airlift reactor [texte imprimé] / Law, Deify, Auteur ; Jones, Samuel T., Auteur ; Heindel, Theodore J., Auteur . - 2011 . - 08 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 2 (Fevrier 2011) . - 08 p. Mots-clés : Airlift  reactor  Bubbly  flows  Computational  fluid  dynamics  Gas  holdup  Hydrodynamics Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The external loop airlift reactor (ELALR) is a modified bubble column reactor that is composed of two vertical columns that are interconnected with two horizontal tubes and is often preferred over traditional bubble column reactors because they can operate over a wider range of conditions. In the present work, the gas-liquid flow dynamics in an ELALR was simulated using an Eulerian–Eulerian ensemble-averaging method in two-dimensional (2D) and three-dimensional (3D) coordinate systems. The computational fluid dynamics (CFD) simulations were compared to experimental measurements from a 10.2 cm diameter ELALR for superficial gas velocities ranging from 1 cm/s to 20 cm/s. The effect of specifying a mean bubble diameter to represent the gas phase in the CFD modeling was investigated, and 2D and 3D simulations were found to be in good agreement with the experimental data. The ELALR flow regimes were compared for the reactor operating in bubble column, closed vent, and open vent modes, and the 2D simulations qualitatively predicted the behavior of bubble growth in the downcomer. However, it was found that 3D simulations were necessary to capture the physics of the ELALR for gas holdup, bulk density differences, and riser superficial liquid velocity. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]

Comparisons of annular hydrodynamic structures in 3D fluidized beds using x-ray computed tomography imaging / Joshua B. Drake in Transactions of the ASME . Journal of fluids engineering, Vol. 134 N° 8 (Août 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 08 p. Titre : Comparisons of annular hydrodynamic structures in 3D fluidized beds using x-ray computed tomography imaging Type de document : texte imprimé Auteurs : Joshua B. Drake, Auteur ; Heindel, Theodore J., Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : annular  flow;  fluidized  bed;  gas  holdup;  hydrodynamic  structure;  x-ray  computed  tomography Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Fluidized beds are common equipment in many process industries. Knowledge of the hydrodynamics within a fluidized bed on the local scale is important for the improvement of scale-up and process efficiencies. This knowledge is lacking due to limited observational technologies at the local scale. This paper uses X-ray computed tomography (CT) imaging to describe the local time-average gas holdup differences of annular hydrodynamic structures that arise through axisymmetric annular flow in a 10.2 cm and 15.2 cm diameter cold flow fluidized bed. The aeration scheme used is similar to that provided by a porous plate and hydrodynamic results can be directly compared. Geldart type B glass bead, ground walnut shell, and crushed corncob particles were studied at various superficial gas velocities. Assuming axisymmetry, the local 3D time-average gas holdup data acquired through X-ray CT imaging was averaged over concentric annuli, resulting in a 2D annular and time-average gas holdup map. These gas holdup maps show that four different types of annular hydrodynamic structures occur in the fluidized beds of this study: zones of (1) aeration jetting, (2) bubble coalescence, (3) bubble rise, and (4) particle shear. Changes in the superficial gas velocities, bed diameters, and bed material densities display changes in these zones. The 2D gas holdup maps provide a benchmark that can be used by computational fluid dynamic (CFD) users for the direct comparisons of 2D models, assuming axisymmetric annular flow. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...] [article] Comparisons of annular hydrodynamic structures in 3D fluidized beds using x-ray computed tomography imaging [texte imprimé] / Joshua B. Drake, Auteur ; Heindel, Theodore J., Auteur . - 2012 . - 08 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 134 N° 8 (Août 2012) . - 08 p. Mots-clés : annular  flow;  fluidized  bed;  gas  holdup;  hydrodynamic  structure;  x-ray  computed  tomography Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Fluidized beds are common equipment in many process industries. Knowledge of the hydrodynamics within a fluidized bed on the local scale is important for the improvement of scale-up and process efficiencies. This knowledge is lacking due to limited observational technologies at the local scale. This paper uses X-ray computed tomography (CT) imaging to describe the local time-average gas holdup differences of annular hydrodynamic structures that arise through axisymmetric annular flow in a 10.2 cm and 15.2 cm diameter cold flow fluidized bed. The aeration scheme used is similar to that provided by a porous plate and hydrodynamic results can be directly compared. Geldart type B glass bead, ground walnut shell, and crushed corncob particles were studied at various superficial gas velocities. Assuming axisymmetry, the local 3D time-average gas holdup data acquired through X-ray CT imaging was averaged over concentric annuli, resulting in a 2D annular and time-average gas holdup map. These gas holdup maps show that four different types of annular hydrodynamic structures occur in the fluidized beds of this study: zones of (1) aeration jetting, (2) bubble coalescence, (3) bubble rise, and (4) particle shear. Changes in the superficial gas velocities, bed diameters, and bed material densities display changes in these zones. The 2D gas holdup maps provide a benchmark that can be used by computational fluid dynamic (CFD) users for the direct comparisons of 2D models, assuming axisymmetric annular flow. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA4000134000008 [...]

Effect of electrolytes on CO-water mass transfer / Haiyang Zhu in Industrial & engineering chemistry research, Vol. 48 N° 6 (Mars 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3206–3210 Titre : Effect of electrolytes on CO-water mass transfer Type de document : texte imprimé Auteurs : Haiyang Zhu, Auteur ; Brent H. Shanks, Auteur ; Heindel, Theodore J., Auteur Année de publication : 2009 Article en page(s) : pp. 3206–3210 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Electrolytes  CO-water  mass  transfer  Mass-transfer  coefficient  MCM41  nanoparticles Résumé : The influence of various electrolytes such as sulfate, nitrate, and chloride on CO−water mass transfer was investigated in this study. The results indicate that the enhancement in the CO−water volumetric mass-transfer coefficient ranged from 1.5 to 4.7 times that of a baseline system without electrolytes, depending on electrolyte type and concentration. For those electrolytes with the same anions, copper-containing electrolytes provided stronger enhancement, whereas for those electrolytes with the same cations, sulfate-containing electrolytes showed stronger enhancement. By measuring both the CO−water volumetric mass-transfer coefficient (kLa) and the mass-transfer coefficient (kL), it was found that the electrolytes inhibit gas bubble coalescence. This leads to an increase in the gas−liquid interfacial area, resulting in CO−water mass-transfer enhancement. In contrast, when MCM41 nanoparticles with or without functionalized mercaptopropyl groups were added to water, the mass-transfer coefficient and CO−water interfacial area were both increased. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8012924 [article] Effect of electrolytes on CO-water mass transfer [texte imprimé] / Haiyang Zhu, Auteur ; Brent H. Shanks, Auteur ; Heindel, Theodore J., Auteur . - 2009 . - pp. 3206–3210. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3206–3210 Mots-clés : Electrolytes  CO-water  mass  transfer  Mass-transfer  coefficient  MCM41  nanoparticles Résumé : The influence of various electrolytes such as sulfate, nitrate, and chloride on CO−water mass transfer was investigated in this study. The results indicate that the enhancement in the CO−water volumetric mass-transfer coefficient ranged from 1.5 to 4.7 times that of a baseline system without electrolytes, depending on electrolyte type and concentration. For those electrolytes with the same anions, copper-containing electrolytes provided stronger enhancement, whereas for those electrolytes with the same cations, sulfate-containing electrolytes showed stronger enhancement. By measuring both the CO−water volumetric mass-transfer coefficient (kLa) and the mass-transfer coefficient (kL), it was found that the electrolytes inhibit gas bubble coalescence. This leads to an increase in the gas−liquid interfacial area, resulting in CO−water mass-transfer enhancement. In contrast, when MCM41 nanoparticles with or without functionalized mercaptopropyl groups were added to water, the mass-transfer coefficient and CO−water interfacial area were both increased. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8012924

Enhancing CO-water mass transfer by functionalized MCM41 nanoparticles / Haiyang Zhu in Industrial & engineering chemistry research, Vol. 47 N°20 (Octobre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°20 (Octobre 2008) . - P. 7881-7887 Titre : Enhancing CO-water mass transfer by functionalized MCM41 nanoparticles Type de document : texte imprimé Auteurs : Haiyang Zhu, Auteur ; Brent H. Shanks, Auteur ; Heindel, Theodore J., Auteur Année de publication : 2008 Article en page(s) : P. 7881-7887 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : CO-Water  Gas Résumé : Organic groups are grafted to ∼250-nm-diameter MCM41 nanoparticles with a spherical morphology to enhance the CO−water volumetric mass-transfer coefficient (kLa) for synthesis gas fermentation. The results indicate that (i) ∼250-nm MCM41 nanoparticles show a higher kLa value than large silica particles (1.4 and 7 μm), (ii) surface hydroxyl groups on MCM41 nanoparticles play an important role in mass-transfer enhancement, (iii) organic groups grafted to MCM41 modify the mass-transfer enhancement, and (iv) mercaptan groups grafted to MCM41 show the most mass-transfer enhancement of ∼1.9 times that of no nanoparticle addition. The CO−water mass-transfer enhancement depends on the interaction between the nanoparticles and the CO molecules, which is influenced by the hydrophobicity of the nanoparticles and the functional group on the nanoparticles. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800238w [article] Enhancing CO-water mass transfer by functionalized MCM41 nanoparticles [texte imprimé] / Haiyang Zhu, Auteur ; Brent H. Shanks, Auteur ; Heindel, Theodore J., Auteur . - 2008 . - P. 7881-7887. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°20 (Octobre 2008) . - P. 7881-7887 Mots-clés : CO-Water  Gas Résumé : Organic groups are grafted to ∼250-nm-diameter MCM41 nanoparticles with a spherical morphology to enhance the CO−water volumetric mass-transfer coefficient (kLa) for synthesis gas fermentation. The results indicate that (i) ∼250-nm MCM41 nanoparticles show a higher kLa value than large silica particles (1.4 and 7 μm), (ii) surface hydroxyl groups on MCM41 nanoparticles play an important role in mass-transfer enhancement, (iii) organic groups grafted to MCM41 modify the mass-transfer enhancement, and (iv) mercaptan groups grafted to MCM41 show the most mass-transfer enhancement of ∼1.9 times that of no nanoparticle addition. The CO−water mass-transfer enhancement depends on the interaction between the nanoparticles and the CO molecules, which is influenced by the hydrophobicity of the nanoparticles and the functional group on the nanoparticles. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800238w

Hydrodynamic considerations in an external loop airlift reactor with a modified downcomer / Jones, Samuel T. in Industrial & engineering chemistry research, Vol. 49 N° 4 (Fevrier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1931–1936 Titre : Hydrodynamic considerations in an external loop airlift reactor with a modified downcomer Type de document : texte imprimé Auteurs : Jones, Samuel T., Auteur ; Heindel, Theodore J., Auteur Année de publication : 2010 Article en page(s) : pp 1931–1936 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Gas  Hydrodynamic  Loop  airlift  reactor. Résumé : Gas holdup and superficial liquid velocity in the downcomer and riser are studied for an external loop airlift reactor with a downcomer-to-riser area ratio of 1:16. Two downcomer configurations are investigated over a range of superficial gas velocities (0.5 ≤ UG ≤ 20 cm/s) using three aeration plate open area ratios (A = 0.62, 0.99, and 2.22%). These results are compared to a bubble column operated with similar operating conditions. Gas holdup in both the riser and downcomer are found to increase with increasing superficial gas velocity. Results show that riser gas holdup varies slightly with downcomer configuration, while a considerable variation is observed for downcomer gas holdup. The superficial liquid velocity varies considerably for the two downcomer configurations and is a function of superficial gas velocity and flow conditions in the downcomer. Observed variations are independent of aeration plate open area ratio. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901311r [article] Hydrodynamic considerations in an external loop airlift reactor with a modified downcomer [texte imprimé] / Jones, Samuel T., Auteur ; Heindel, Theodore J., Auteur . - 2010 . - pp 1931–1936. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1931–1936 Mots-clés : Gas  Hydrodynamic  Loop  airlift  reactor. Résumé : Gas holdup and superficial liquid velocity in the downcomer and riser are studied for an external loop airlift reactor with a downcomer-to-riser area ratio of 1:16. Two downcomer configurations are investigated over a range of superficial gas velocities (0.5 ≤ UG ≤ 20 cm/s) using three aeration plate open area ratios (A = 0.62, 0.99, and 2.22%). These results are compared to a bubble column operated with similar operating conditions. Gas holdup in both the riser and downcomer are found to increase with increasing superficial gas velocity. Results show that riser gas holdup varies slightly with downcomer configuration, while a considerable variation is observed for downcomer gas holdup. The superficial liquid velocity varies considerably for the two downcomer configurations and is a function of superficial gas velocity and flow conditions in the downcomer. Observed variations are independent of aeration plate open area ratio. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901311r