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Hydrodynamics of electrostatic charge in polypropylene fluidized beds / Piyawan Tiyapiboonchaiya a in Industrial & engineering chemistry research, Vol. 51 N° 25 (Juin 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 25 (Juin 2012) . - pp. 8661-8668 Titre : Hydrodynamics of electrostatic charge in polypropylene fluidized beds Type de document : texte imprimé Auteurs : Piyawan Tiyapiboonchaiya a, Auteur ; Dimitri Gidaspow, Auteur ; Somsak Damronglerd, Auteur Année de publication : 2012 Article en page(s) : pp. 8661-8668 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Fluidized  bed  Fluidization  Electrostatic  charge  Hydrodynamics Résumé : Experiments were performed in a double jacket gas―solid fluidized bed to investigate the process and degree of electrification in polypropylene fluidized beds. Five copper rings attached to the inner column wall were connected to a picoammeter for measuring the electrical current at the different vertical levels. It was found that both positive and negative electrical currents were traced in the whole bed. The magnitude of positive current value was observed at the bottom of the bed while at the top part of the bed the magnitude of negative current value was found The influence of initial bed height, fluidization velocity, and gas temperature on the degree of electrification was investigated. The effect of gas temperature played a significant role in the charge dissipation. Also, the degree of electrification increased with initial bed height and gas velocity. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26066793 [article] Hydrodynamics of electrostatic charge in polypropylene fluidized beds [texte imprimé] / Piyawan Tiyapiboonchaiya a, Auteur ; Dimitri Gidaspow, Auteur ; Somsak Damronglerd, Auteur . - 2012 . - pp. 8661-8668. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 25 (Juin 2012) . - pp. 8661-8668 Mots-clés : Fluidized  bed  Fluidization  Electrostatic  charge  Hydrodynamics Résumé : Experiments were performed in a double jacket gas―solid fluidized bed to investigate the process and degree of electrification in polypropylene fluidized beds. Five copper rings attached to the inner column wall were connected to a picoammeter for measuring the electrical current at the different vertical levels. It was found that both positive and negative electrical currents were traced in the whole bed. The magnitude of positive current value was observed at the bottom of the bed while at the top part of the bed the magnitude of negative current value was found The influence of initial bed height, fluidization velocity, and gas temperature on the degree of electrification was investigated. The effect of gas temperature played a significant role in the charge dissipation. Also, the degree of electrification increased with initial bed height and gas velocity. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26066793

Kinetic theory explanation of a circulating fluidized bed ring structure near choking / Mehmet Tartan in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 326-329 Titre : Kinetic theory explanation of a circulating fluidized bed ring structure near choking Type de document : texte imprimé Auteurs : Mehmet Tartan, Editeur scientifique ; Dimitri Gidaspow, Editeur scientifique ; Veeraya Jiradilok, Editeur scientifique Année de publication : 2009 Article en page(s) : P. 326-329 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Kinetic  theory  Ring  structure  Fluidized  catalytic  cracking  (FCC) Résumé : The objective of this technical note is to give an alternate explanation of the ring structure behavior for the flow of fluidized catalytic cracking (FCC) particles in a riser recently obtained in L. S. Fan’s laboratory. Their recent explanation of this phenomenon is due to the low velocity at the center. While indeed this is one of the causes of the high concentration near the center, we show that an additional driving force for the higher concentration at the center is the low granular temperature caused by the dissipation of random kinetic energy at the center of the riser. An approximate analytical solution applied to the flow of FCC particles obtained in Fan’s laboratory again produces a dip in the granular temperature in the center and hence a rise in the particle concentration. This phenomenon occurs as a result of the constancy of solids pressure in the developed region of the riser. It is the so-called shear-induced diffusion effect well-known for neutrally buoyant particles in liquids. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8007192 [article] Kinetic theory explanation of a circulating fluidized bed ring structure near choking [texte imprimé] / Mehmet Tartan, Editeur scientifique ; Dimitri Gidaspow, Editeur scientifique ; Veeraya Jiradilok, Editeur scientifique . - 2009 . - P. 326-329. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 326-329 Mots-clés : Kinetic  theory  Ring  structure  Fluidized  catalytic  cracking  (FCC) Résumé : The objective of this technical note is to give an alternate explanation of the ring structure behavior for the flow of fluidized catalytic cracking (FCC) particles in a riser recently obtained in L. S. Fan’s laboratory. Their recent explanation of this phenomenon is due to the low velocity at the center. While indeed this is one of the causes of the high concentration near the center, we show that an additional driving force for the higher concentration at the center is the low granular temperature caused by the dissipation of random kinetic energy at the center of the riser. An approximate analytical solution applied to the flow of FCC particles obtained in Fan’s laboratory again produces a dip in the granular temperature in the center and hence a rise in the particle concentration. This phenomenon occurs as a result of the constancy of solids pressure in the developed region of the riser. It is the so-called shear-induced diffusion effect well-known for neutrally buoyant particles in liquids. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8007192

Measurements of dispersion coefficients for FCC particles in a free board / Mayank Kashyap in Industrial & engineering chemistry research, Vol. 50 N° 12 (Juin 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 12 (Juin 2011) . - pp. 7549-7565 Titre : Measurements of dispersion coefficients for FCC particles in a free board Type de document : texte imprimé Auteurs : Mayank Kashyap, Auteur ; Dimitri Gidaspow, Auteur Année de publication : 2011 Article en page(s) : pp. 7549-7565 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Dispersion Résumé : Particle image velocimetry (PIV) experiments were performed noninvasively in the Illinois Institute of Technology (IIT) two-dimensional circulating fluidized bed (2-D CFB) of fluid catalytic cracking (FCC) particles to measure laminar and turbulent properties, near the front wall in the z-direction; at the center and near the right and left walls in the x-direction; and in the free board region in the y-direction. The PIV measurements were obtained simultaneously in the y- and x-axes, using a charge-coupled device (CCD) camera, with the aid of a colored rotating transparency. The instantaneous and hydrodynamic velocities were used to obtain laminar properties for particles and turbulent properties for clusters, respectively. Laminar and turbulent properties for solids conveyed anisotropy. The y-axis solids velocities, power spectral densities of hydrodynamic velocities, and granular temperatures were highest at the center in the x-direction. The mixing was on the level of particles. The y- and x-axes solids dispersion coefficients were several orders of magnitude lower than the literature values, because of the low particle velocities in the free board. However, total granular temperatures were reasonably close to the literature values. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24239072 [article] Measurements of dispersion coefficients for FCC particles in a free board [texte imprimé] / Mayank Kashyap, Auteur ; Dimitri Gidaspow, Auteur . - 2011 . - pp. 7549-7565. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 12 (Juin 2011) . - pp. 7549-7565 Mots-clés : Dispersion Résumé : Particle image velocimetry (PIV) experiments were performed noninvasively in the Illinois Institute of Technology (IIT) two-dimensional circulating fluidized bed (2-D CFB) of fluid catalytic cracking (FCC) particles to measure laminar and turbulent properties, near the front wall in the z-direction; at the center and near the right and left walls in the x-direction; and in the free board region in the y-direction. The PIV measurements were obtained simultaneously in the y- and x-axes, using a charge-coupled device (CCD) camera, with the aid of a colored rotating transparency. The instantaneous and hydrodynamic velocities were used to obtain laminar properties for particles and turbulent properties for clusters, respectively. Laminar and turbulent properties for solids conveyed anisotropy. The y-axis solids velocities, power spectral densities of hydrodynamic velocities, and granular temperatures were highest at the center in the x-direction. The mixing was on the level of particles. The y- and x-axes solids dispersion coefficients were several orders of magnitude lower than the literature values, because of the low particle velocities in the free board. However, total granular temperatures were reasonably close to the literature values. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24239072