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Electrostatics generation in a small cyclone separator / Zhongxiang Chen 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. 185-190 Titre : Electrostatics generation in a small cyclone separator Type de document : texte imprimé Auteurs : Zhongxiang Chen, Editeur scientifique ; Hsiaotao T. Bi, Editeur scientifique Année de publication : 2009 Article en page(s) : p. 185-190 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Electrostatics Résumé : Experiments were conducted in a small cyclone separator (50 mm inner diameter) with two grades of commercial polyethylene particles, to study the electrostatic charge generation during the gas−solid transportation and separation. Results show clearly that the charges generated in the cyclone test unit were quite reproducible. When solid particles were fed to the cyclone, there was an abrupt change in the current flow and a quick increase of (negative) charge generation for both types of polyethylene particles. Both the charge density and the charge generation rate were always higher for the particles of higher density and smaller mean size. For both types of polyethylene, the (negative) charge density increased almost linearly with the gas velocity. When the solid feed rate or initial solid loading increased, the magnitude of the charge density decreased because there were fewer particle−wall collisions at higher solids feeding rate or higher solids concentration, due to shielding effects. Results indicate that the pipe section contributed <10% of the total charge generation for both grades of polyethylene, with charge generation being dominated by the interaction between the particles and the cyclone internal surface. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071502p [article] Electrostatics generation in a small cyclone separator [texte imprimé] / Zhongxiang Chen, Editeur scientifique ; Hsiaotao T. Bi, Editeur scientifique . - 2009 . - p. 185-190. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - p. 185-190 Mots-clés : Electrostatics Résumé : Experiments were conducted in a small cyclone separator (50 mm inner diameter) with two grades of commercial polyethylene particles, to study the electrostatic charge generation during the gas−solid transportation and separation. Results show clearly that the charges generated in the cyclone test unit were quite reproducible. When solid particles were fed to the cyclone, there was an abrupt change in the current flow and a quick increase of (negative) charge generation for both types of polyethylene particles. Both the charge density and the charge generation rate were always higher for the particles of higher density and smaller mean size. For both types of polyethylene, the (negative) charge density increased almost linearly with the gas velocity. When the solid feed rate or initial solid loading increased, the magnitude of the charge density decreased because there were fewer particle−wall collisions at higher solids feeding rate or higher solids concentration, due to shielding effects. Results indicate that the pipe section contributed <10% of the total charge generation for both grades of polyethylene, with charge generation being dominated by the interaction between the particles and the cyclone internal surface. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071502p

Study on void behavior in a turbulent fluidized bed with catalyst powders / Xiaoping Zhang in Industrial & engineering chemistry research, Vol. 49 N° 15 (Août 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6862–6869 Titre : Study on void behavior in a turbulent fluidized bed with catalyst powders Type de document : texte imprimé Auteurs : Xiaoping Zhang, Auteur ; Hsiaotao T. Bi, Auteur Année de publication : 2010 Article en page(s) : pp 6862–6869 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Fluidized  bed  Turbulent  Catalyst  powders. Résumé : Turbulent fluidized beds have been recognized as very effective gas−solids contacting devices because of their outstanding performance in gas−solids contact, heat transfer, and mass transfer. To characterize the void behavior, which governs the hydrodynamics and the efficiency of operation of turbulent fluidized beds, an optical fiber probe with a separation distance of 5 mm between the two measuring tips has been used to measure the axial and radial profiles of the bubble/void parameters in a turbulent fluidized bed over a gas velocity range of 0.4−1.0 m/s. Experiments were carried out in a Plexiglas column with an inner diameter of 0.19 m and a height of 5.5 m. Fluid cracking catalyst (FCC) powders with a mean size of 78 μm were used as bed particles, and air was used as the fluidizing gas. Signals from the optical fiber probe were used to obtain the rise velocity and the chord length of voids at various spatial positions and superficial gas velocities. The results show that, in the turbulent fluidization regime, the void size and the void rise velocity have a relatively uniform distribution along the radial direction in the bed. Based on the assumption that bubble splitting is dominant over bubble coalescence at high superficial gas velocities, a modified bubble coalescence−splitting balance model was found to give reasonable agreement with the measured void size profiles. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901715z [article] Study on void behavior in a turbulent fluidized bed with catalyst powders [texte imprimé] / Xiaoping Zhang, Auteur ; Hsiaotao T. Bi, Auteur . - 2010 . - pp 6862–6869. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6862–6869 Mots-clés : Fluidized  bed  Turbulent  Catalyst  powders. Résumé : Turbulent fluidized beds have been recognized as very effective gas−solids contacting devices because of their outstanding performance in gas−solids contact, heat transfer, and mass transfer. To characterize the void behavior, which governs the hydrodynamics and the efficiency of operation of turbulent fluidized beds, an optical fiber probe with a separation distance of 5 mm between the two measuring tips has been used to measure the axial and radial profiles of the bubble/void parameters in a turbulent fluidized bed over a gas velocity range of 0.4−1.0 m/s. Experiments were carried out in a Plexiglas column with an inner diameter of 0.19 m and a height of 5.5 m. Fluid cracking catalyst (FCC) powders with a mean size of 78 μm were used as bed particles, and air was used as the fluidizing gas. Signals from the optical fiber probe were used to obtain the rise velocity and the chord length of voids at various spatial positions and superficial gas velocities. The results show that, in the turbulent fluidization regime, the void size and the void rise velocity have a relatively uniform distribution along the radial direction in the bed. Based on the assumption that bubble splitting is dominant over bubble coalescence at high superficial gas velocities, a modified bubble coalescence−splitting balance model was found to give reasonable agreement with the measured void size profiles. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901715z