Documents disponibles écrits par cet auteur

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

Effect of change in fluidizing gas on riser hydrodynamics and evaluation of scaling laws / Naoko Ellis 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. 4697–4706 Titre : Effect of change in fluidizing gas on riser hydrodynamics and evaluation of scaling laws Type de document : texte imprimé Auteurs : Naoko Ellis, Auteur ; Min Xu, Auteur ; C. Jim Lim, Auteur Année de publication : 2011 Article en page(s) : pp. 4697–4706 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Fluidizing  Gas Résumé : Riser hydrodynamics in a circulating fluidized bed are investigated experimentally and numerically by changing the composition of the fluidizing gas. Helium gas is added to air in the range of 0 to 96 vol % for fluidizing FCC particles 78 μm in size and density of 1560 kg/m3. Increasing He concentration decreases the fluidizing gas density and viscosity. The effect of change in gas composition is measured through the change in voidage along the riser from the pressure drop and the solids circulation rate, while analyzed by changes in slip velocity and particle Reynolds number. Numerical simulations using Computational Fluid Dynamics (CFD) have successfully predicted the experimental measurements over the entire range of fluidizing gas densities investigated. Simulations have also revealed that interphase momentum exchange in the bottom, accelerated region of the riser is dominated by cluster formation, while individual particle drag was dominant in the upper, more dilute regions. Given that CFD simulations have successfully reproduced these results, a scaling scheme is investigated whereby a hot model unit is simulated keeping either the Archimedes number or the density ratio of particle to gas constant. The results indicated better agreement between experimental and numerical voidage profiles for the density ratio scaling. Using the full set of scaling laws produced excellent prediction of the upper, fully developed region of the riser, but failed in the bottom regions. The scaling error in the bottom region was attributed to the momentum interaction in this region being dominated by cluster formation and not by the drag force on individual particles for which the scaling laws were derived. CFD has shown to be an effective tool in evaluation of scaling laws in risers. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101141f [article] Effect of change in fluidizing gas on riser hydrodynamics and evaluation of scaling laws [texte imprimé] / Naoko Ellis, Auteur ; Min Xu, Auteur ; C. Jim Lim, Auteur . - 2011 . - pp. 4697–4706. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 8 (Avril 2011) . - pp. 4697–4706 Mots-clés : Fluidizing  Gas Résumé : Riser hydrodynamics in a circulating fluidized bed are investigated experimentally and numerically by changing the composition of the fluidizing gas. Helium gas is added to air in the range of 0 to 96 vol % for fluidizing FCC particles 78 μm in size and density of 1560 kg/m3. Increasing He concentration decreases the fluidizing gas density and viscosity. The effect of change in gas composition is measured through the change in voidage along the riser from the pressure drop and the solids circulation rate, while analyzed by changes in slip velocity and particle Reynolds number. Numerical simulations using Computational Fluid Dynamics (CFD) have successfully predicted the experimental measurements over the entire range of fluidizing gas densities investigated. Simulations have also revealed that interphase momentum exchange in the bottom, accelerated region of the riser is dominated by cluster formation, while individual particle drag was dominant in the upper, more dilute regions. Given that CFD simulations have successfully reproduced these results, a scaling scheme is investigated whereby a hot model unit is simulated keeping either the Archimedes number or the density ratio of particle to gas constant. The results indicated better agreement between experimental and numerical voidage profiles for the density ratio scaling. Using the full set of scaling laws produced excellent prediction of the upper, fully developed region of the riser, but failed in the bottom regions. The scaling error in the bottom region was attributed to the momentum interaction in this region being dominated by cluster formation and not by the drag force on individual particles for which the scaling laws were derived. CFD has shown to be an effective tool in evaluation of scaling laws in risers. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101141f

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) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 6 (Mars 2011) . - pp. 3110–3129 Titre : Modeling of a fluidized bed membrane reactor for hydrogen production by steam reforming of hydrocarbons Type de document : texte imprimé Auteurs : Mohammad A. Rakib, Auteur ; John R. Grace, Auteur ; C. Jim Lim, Auteur Année de publication : 2011 Article en page(s) : pp. 3110–3129 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Membrane  reactor  Hydrogen  production Résumé : A bubbling fluidized bed membrane reactor (FBMR) is modeled to estimate and predict the steam reforming of hydrocarbons. A two-phase fluidization model is used, with both the bubble and dense phases in plug flow. Diffusional mass transfer, as well as bulk convective mass flow between the phases, is incorporated to account for reactions occurring predominantly in the dense phase and increases in molar flow due to the reaction. Steam reforming of higher hydrocarbons is limited by the thermodynamic equilibrium of the methane steam reforming and water−gas shift reactions. The model predicts flexible feedstock capabilities, showing that most of the reactor does not actually see the higher hydrocarbon feed. With a single fitted constant to account for membrane effectiveness in the fluidized bed relative to that in the absence of particles, good agreement is obtained between model predictions and reactor performance of the reforming of methane, propane, and heptane. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100954a [article] Modeling of a fluidized bed membrane reactor for hydrogen production by steam reforming of hydrocarbons [texte imprimé] / Mohammad A. Rakib, Auteur ; John R. Grace, Auteur ; C. Jim Lim, Auteur . - 2011 . - pp. 3110–3129. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 6 (Mars 2011) . - pp. 3110–3129 Mots-clés : Membrane  reactor  Hydrogen  production Résumé : A bubbling fluidized bed membrane reactor (FBMR) is modeled to estimate and predict the steam reforming of hydrocarbons. A two-phase fluidization model is used, with both the bubble and dense phases in plug flow. Diffusional mass transfer, as well as bulk convective mass flow between the phases, is incorporated to account for reactions occurring predominantly in the dense phase and increases in molar flow due to the reaction. Steam reforming of higher hydrocarbons is limited by the thermodynamic equilibrium of the methane steam reforming and water−gas shift reactions. The model predicts flexible feedstock capabilities, showing that most of the reactor does not actually see the higher hydrocarbon feed. With a single fitted constant to account for membrane effectiveness in the fluidized bed relative to that in the absence of particles, good agreement is obtained between model predictions and reactor performance of the reforming of methane, propane, and heptane. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100954a