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CO2 Capture and Hydrogen Production in an Integrated Fluidized Bed Reformer-Regenerator System / Zhongxiang Chen in Industrial & engineering chemistry research, Vol. 50 N° 8 (Avril 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 8 (Avril 2011) . - pp. 4716–4721 Titre : CO2 Capture and Hydrogen Production in an Integrated Fluidized Bed Reformer-Regenerator System Type de document : texte imprimé Auteurs : Zhongxiang Chen, Auteur ; John R. Grace, Auteur ; C. Jim Lim, Auteur Année de publication : 2011 Article en page(s) : pp. 4716–4721 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : CO2  capture  hydrogen  Regenerator  system Résumé : Thermodynamic analysis of CO2 capture and hydrogen production for steam methane reforming was carried out using ASPEN simulation software. The integrated reaction system is composed of a sorbent-enhanced fluidized bed reformer coupled with a fluidized bed sorbent regenerator (calciner) where fine CaO-based sorbents (100 μm mean particle diameter) were used. The system performance is evaluated as a function of a number of operating parameters for both the reformer and regenerator. The results indicate that the optimum operating parameters for reformer are temperatures from 550 to 600 °C, low pressure, steam-to-carbon molar feed ratio of 3.5, and sorbent circulation flow rate exceeding the minimum stoichiometric feed rate of active sorbent. For the sorbent regenerator, the optimum conditions are temperatures above 850 °C, low pressure, and enough sweep gas flow to completely calcine CaCO3. On the basis of thermodynamics, it should be possible to achieve a hydrogen purity of 98% and a CO2 purity in excess of 99% after condensing sweep steam downstream. The predicted hydrogen purity is consistent with previous experiments. The high-concentration CO2 should be suitable for sequestration or for industrial use. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101360x [article] CO2 Capture and Hydrogen Production in an Integrated Fluidized Bed Reformer-Regenerator System [texte imprimé] / Zhongxiang Chen, Auteur ; John R. Grace, Auteur ; C. Jim Lim, Auteur . - 2011 . - pp. 4716–4721. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 8 (Avril 2011) . - pp. 4716–4721 Mots-clés : CO2  capture  hydrogen  Regenerator  system Résumé : Thermodynamic analysis of CO2 capture and hydrogen production for steam methane reforming was carried out using ASPEN simulation software. The integrated reaction system is composed of a sorbent-enhanced fluidized bed reformer coupled with a fluidized bed sorbent regenerator (calciner) where fine CaO-based sorbents (100 μm mean particle diameter) were used. The system performance is evaluated as a function of a number of operating parameters for both the reformer and regenerator. The results indicate that the optimum operating parameters for reformer are temperatures from 550 to 600 °C, low pressure, steam-to-carbon molar feed ratio of 3.5, and sorbent circulation flow rate exceeding the minimum stoichiometric feed rate of active sorbent. For the sorbent regenerator, the optimum conditions are temperatures above 850 °C, low pressure, and enough sweep gas flow to completely calcine CaCO3. On the basis of thermodynamics, it should be possible to achieve a hydrogen purity of 98% and a CO2 purity in excess of 99% after condensing sweep steam downstream. The predicted hydrogen purity is consistent with previous experiments. The high-concentration CO2 should be suitable for sequestration or for industrial use. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101360x

Computational fluid dynamic investigation of change of volumetric flow in fluidized-bed reactors / Tingwen Li 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 6780–6789 Titre : Computational fluid dynamic investigation of change of volumetric flow in fluidized-bed reactors Type de document : texte imprimé Auteurs : Tingwen Li, Auteur ; Andrés Mahecha-Botero, Auteur ; John R. Grace, Auteur Année de publication : 2010 Article en page(s) : pp 6780–6789 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Fluid  Dynamic  Volumetric  flow. Résumé : The modeling and characterization of fluidized-bed reactors is challenging due to the variety of interrelated phenomena during the fluidization process. A key feature affecting gas−solid fluidized-bed reactors is the distribution of gas flow between phases. To address this flow distribution, conventional reactor modeling and computational fluid dynamics have been proposed in the literature. However, very little attention has been given to cases where the fluid volume changes due to factors such as variation in the total molar flow due to reaction, change of phase, utilization of membranes, and changes in temperature and pressure. This article investigates change in volumetric flow based on computational fluid dynamics. It is shown that a decrease in volumetric flow can profoundly influence the hydrodynamics, especially for smaller particles, whereas an increase in volumetric flow is accommodated with limited consequences, especially for larger particles. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901676d [article] Computational fluid dynamic investigation of change of volumetric flow in fluidized-bed reactors [texte imprimé] / Tingwen Li, Auteur ; Andrés Mahecha-Botero, Auteur ; John R. Grace, Auteur . - 2010 . - pp 6780–6789. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6780–6789 Mots-clés : Fluid  Dynamic  Volumetric  flow. Résumé : The modeling and characterization of fluidized-bed reactors is challenging due to the variety of interrelated phenomena during the fluidization process. A key feature affecting gas−solid fluidized-bed reactors is the distribution of gas flow between phases. To address this flow distribution, conventional reactor modeling and computational fluid dynamics have been proposed in the literature. However, very little attention has been given to cases where the fluid volume changes due to factors such as variation in the total molar flow due to reaction, change of phase, utilization of membranes, and changes in temperature and pressure. This article investigates change in volumetric flow based on computational fluid dynamics. It is shown that a decrease in volumetric flow can profoundly influence the hydrodynamics, especially for smaller particles, whereas an increase in volumetric flow is accommodated with limited consequences, especially for larger particles. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901676d

Effects of pressure, temperature, and gas velocity on electrostatics in gas-solid fluidized beds / Wajeeh O. Moughrabiah 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. 320-325 Titre : Effects of pressure, temperature, and gas velocity on electrostatics in gas-solid fluidized beds Type de document : texte imprimé Auteurs : Wajeeh O. Moughrabiah, Editeur scientifique ; John R. Grace, Editeur scientifique ; Xiaotao T. Bi, Editeur scientifique Année de publication : 2009 Article en page(s) : P. 320-325 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Effects  of  Pressure  Temperature  Electrostatics  Gas−Solid Résumé : The influences of operating pressure, temperature, and gas velocity on the degree of electrification in a fluidized bed of glass beads and different grades of polyethylene resin were investigated in a fluidization column of 150-mm inner diameter and 2.0-m height. Eight collision ball probes at different levels and radial positions measured the degree of electrification in the bed. Faraday cups also measured the charge density in the bed by taking samples from three different online sampling ports at different levels. The degree of electrification increased as pressure increased from 1.0 to 8.0 bar, probably due to an increase in bubble rise velocity, frequency, and volume fraction. The maximum static charges were found at approximately two-thirds of the bed height and near the axis. As the pressure increased, particle−particle and particle−wall collisions near the distributor and wall contributed heavily to static charge generation. At higher temperatures (up to 75 °C), the bed exhibited smoother fluidization. Temperature played a significant role in determining electrostatic charging. As the superficial gas velocity increased from 0.23 to 0.40 m/s, the degree of electrification increased. However, at higher gas velocities, the polarity in the freeboard region was opposite to that in the bed, indicating that fines entrained from the column carried charges, resulting in a net charge of polarity opposite to that inside the bed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800556y [article] Effects of pressure, temperature, and gas velocity on electrostatics in gas-solid fluidized beds [texte imprimé] / Wajeeh O. Moughrabiah, Editeur scientifique ; John R. Grace, Editeur scientifique ; Xiaotao T. Bi, Editeur scientifique . - 2009 . - P. 320-325. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 320-325 Mots-clés : Effects  of  Pressure  Temperature  Electrostatics  Gas−Solid Résumé : The influences of operating pressure, temperature, and gas velocity on the degree of electrification in a fluidized bed of glass beads and different grades of polyethylene resin were investigated in a fluidization column of 150-mm inner diameter and 2.0-m height. Eight collision ball probes at different levels and radial positions measured the degree of electrification in the bed. Faraday cups also measured the charge density in the bed by taking samples from three different online sampling ports at different levels. The degree of electrification increased as pressure increased from 1.0 to 8.0 bar, probably due to an increase in bubble rise velocity, frequency, and volume fraction. The maximum static charges were found at approximately two-thirds of the bed height and near the axis. As the pressure increased, particle−particle and particle−wall collisions near the distributor and wall contributed heavily to static charge generation. At higher temperatures (up to 75 °C), the bed exhibited smoother fluidization. Temperature played a significant role in determining electrostatic charging. As the superficial gas velocity increased from 0.23 to 0.40 m/s, the degree of electrification increased. However, at higher gas velocities, the polarity in the freeboard region was opposite to that in the bed, indicating that fines entrained from the column carried charges, resulting in a net charge of polarity opposite to that inside the bed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800556y

Gas back-mixing in a two-dimensional baffled turbulent fluidized bed / Yongmin Zhang in Industrial & engineering chemistry research, Vol. 47 n°21 (Novembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8484–8491 Titre : Gas back-mixing in a two-dimensional baffled turbulent fluidized bed Type de document : texte imprimé Auteurs : Yongmin Zhang, Auteur ; Chunxi Lu, Auteur ; John R. Grace, Auteur Année de publication : 2008 Article en page(s) : p. 8484–8491 Note générale : chemical engineering Langues : Anglais (eng) Mots-clés : Turbulent  fluidized Résumé : The effect of louver baffles on gas back-mixing was investigated in a large-scale two-dimensional fluidized bed of fluid catalytic cracking (FCC) particles with helium as tracer gas. The axial gas dispersion coefficient of the baffle-free fluidized bed first increased with increasing superficial gas velocity and then decreased after reaching a maximum near the onset of the turbulent flow regime. “Gulf streaming” of emulsion flow in the baffle-free bed determined the lateral profiles of tracer gas concentration. Solids back-mixing flux was greatly reduced by the addition of a layer of louver baffles, while solids mixing above the baffle layer was enhanced. The modified baffled fluidized bed with multilayer louver baffles not only provided a high efficiency of gas−solids contacting but also greatly suppressed the back-mixing of both gas and solids. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800906n [article] Gas back-mixing in a two-dimensional baffled turbulent fluidized bed [texte imprimé] / Yongmin Zhang, Auteur ; Chunxi Lu, Auteur ; John R. Grace, Auteur . - 2008 . - p. 8484–8491. chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8484–8491 Mots-clés : Turbulent  fluidized Résumé : The effect of louver baffles on gas back-mixing was investigated in a large-scale two-dimensional fluidized bed of fluid catalytic cracking (FCC) particles with helium as tracer gas. The axial gas dispersion coefficient of the baffle-free fluidized bed first increased with increasing superficial gas velocity and then decreased after reaching a maximum near the onset of the turbulent flow regime. “Gulf streaming” of emulsion flow in the baffle-free bed determined the lateral profiles of tracer gas concentration. Solids back-mixing flux was greatly reduced by the addition of a layer of louver baffles, while solids mixing above the baffle layer was enhanced. The modified baffled fluidized bed with multilayer louver baffles not only provided a high efficiency of gas−solids contacting but also greatly suppressed the back-mixing of both gas and solids. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800906n

Limestone Particle Attrition in High-Velocity Air Jets / Gang Xiao in Industrial & engineering chemistry research, Vol. 51 N° 1 (Janvier 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 1 (Janvier 2012) . - pp. 556-560 Titre : Limestone Particle Attrition in High-Velocity Air Jets Type de document : texte imprimé Auteurs : Gang Xiao, Auteur ; John R. Grace, Auteur ; C. Jim Lim, Auteur Année de publication : 2012 Article en page(s) : pp. 556-560 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Air  jet  Attrition Résumé : Experiments were carried out with limestone particles of several narrow size intervals (125―180, 250―300, 355―425, 500―600, 600―710, 710―850, and 850―1037 μm) for times ranging from 0.5 to 144 h in a high-velocity jet apparatus to provide a more comprehensive understanding of jet attrition. The theory of cumulative damage for fatigue is applied to explain the particle attrition mechanisms and to build an attrition model. Fines generation processes differed for limestone particles of different initial sizes, especially in the initial stage, because of the effects of rough surfaces and cumulative damage needed for attrition. In the model, the fines generation rates in the initial stage was well fitted by an exponential function with an index inversely proportional to the particle volume until stable stages were reached, whereas the rate of fines generation during the stable stage appeared to be constant for narrowly sized limestone particles. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25476501 [article] Limestone Particle Attrition in High-Velocity Air Jets [texte imprimé] / Gang Xiao, Auteur ; John R. Grace, Auteur ; C. Jim Lim, Auteur . - 2012 . - pp. 556-560. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 1 (Janvier 2012) . - pp. 556-560 Mots-clés : Air  jet  Attrition Résumé : Experiments were carried out with limestone particles of several narrow size intervals (125―180, 250―300, 355―425, 500―600, 600―710, 710―850, and 850―1037 μm) for times ranging from 0.5 to 144 h in a high-velocity jet apparatus to provide a more comprehensive understanding of jet attrition. The theory of cumulative damage for fatigue is applied to explain the particle attrition mechanisms and to build an attrition model. Fines generation processes differed for limestone particles of different initial sizes, especially in the initial stage, because of the effects of rough surfaces and cumulative damage needed for attrition. In the model, the fines generation rates in the initial stage was well fitted by an exponential function with an index inversely proportional to the particle volume until stable stages were reached, whereas the rate of fines generation during the stable stage appeared to be constant for narrowly sized limestone particles. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25476501

Modeling of a fluidized bed membrane reactor for hydrogen production by steam reforming of hydrocarbons / Mohammad A. Rakib in Industrial & engineering chemistry research, Vol. 50 N° 6 (Mars 2011) 

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