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Analysis of the acceleration region in a circulating fluidized bed riser operating above fast fluidization velocities / Esmail R. Monazam 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. 8423–8429 Titre : Analysis of the acceleration region in a circulating fluidized bed riser operating above fast fluidization velocities Type de document : texte imprimé Auteurs : Esmail R. Monazam, Auteur ; Lawrence J. Shadle, Auteur Année de publication : 2008 Article en page(s) : p. 8423–8429 Note générale : Chmical engineering Langues : Anglais (eng) Mots-clés : Analysis  of  the  acceleration Résumé : In commercial circulating fluidized bed (CFB) processes the acceleration zone greatly contributes to solids mixing, gas and solids dispersion, and particle residence times. A new analysis was developed to describe the relative gas−solids concentration in the acceleration region of a transport system with air as the fluidizing agent for Geldart-type B particles. A theoretical expression was derived from a drag relationship and momentum and continuity equations to describe the evolution of the gas−solids profile along the axial direction. The acceleration zone was characterized using nondimensional analysis of the continuum equations (balances of masses and momenta) that described multiphase flows. In addition to acceleration length, the boundary condition for the solids fraction at the bottom of the riser and the fully developed regions were measured using an industrial scale CFB of 0.3 m diameter and 15 m tall. The operating factors affecting the flow development in the acceleration region were determined for three materials of various sizes and densities in core annular and dilute regimes of the riser. Performance data were taken from statistically designed experiments over a wide range of Fr (0.5−39), Re (8−600), Ar (29−3600), load ratio (0.2−28), riser to particle diameter ratio (375−5000), and gas to solids density ratio (138−1381). In this one-dimensional system of equations, velocities and solid fractions were assumed to be constant over any cross section. The model and engineering correlations were compared with literature expressions to assess their validity and range of applicability. These expressions can be used as tools for simulation and design of a CFB riser and can also be easily coupled to a kinetics model for process simulation. [article] Analysis of the acceleration region in a circulating fluidized bed riser operating above fast fluidization velocities [texte imprimé] / Esmail R. Monazam, Auteur ; Lawrence J. Shadle, Auteur . - 2008 . - p. 8423–8429. Chmical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8423–8429 Mots-clés : Analysis  of  the  acceleration Résumé : In commercial circulating fluidized bed (CFB) processes the acceleration zone greatly contributes to solids mixing, gas and solids dispersion, and particle residence times. A new analysis was developed to describe the relative gas−solids concentration in the acceleration region of a transport system with air as the fluidizing agent for Geldart-type B particles. A theoretical expression was derived from a drag relationship and momentum and continuity equations to describe the evolution of the gas−solids profile along the axial direction. The acceleration zone was characterized using nondimensional analysis of the continuum equations (balances of masses and momenta) that described multiphase flows. In addition to acceleration length, the boundary condition for the solids fraction at the bottom of the riser and the fully developed regions were measured using an industrial scale CFB of 0.3 m diameter and 15 m tall. The operating factors affecting the flow development in the acceleration region were determined for three materials of various sizes and densities in core annular and dilute regimes of the riser. Performance data were taken from statistically designed experiments over a wide range of Fr (0.5−39), Re (8−600), Ar (29−3600), load ratio (0.2−28), riser to particle diameter ratio (375−5000), and gas to solids density ratio (138−1381). In this one-dimensional system of equations, velocities and solid fractions were assumed to be constant over any cross section. The model and engineering correlations were compared with literature expressions to assess their validity and range of applicability. These expressions can be used as tools for simulation and design of a CFB riser and can also be easily coupled to a kinetics model for process simulation.

Performance and kinetics of a solid amine sorbent for carbon dioxide removal / Esmail R. Monazam in Industrial & engineering chemistry research, Vol. 50 N° 19 (Octobre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 19 (Octobre 2011) . - pp. 10989–10995 Titre : Performance and kinetics of a solid amine sorbent for carbon dioxide removal Type de document : texte imprimé Auteurs : Esmail R. Monazam, Auteur ; Lawrence J. Shadle, Auteur ; Ranjani Siriwardane, Auteur Année de publication : 2011 Article en page(s) : pp. 10989–10995 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Kinetics  Solid  amine  sorbent Résumé : The kinetics of the reaction between CO2 and amine/bentonite particle were estimated over the range of 303–363 K from adsorption data obtained by TGA. The weight percent of amine, reaction temperature, and particle diameter were considered as experimental variables. The sorbent maximum or equilibrium CO2 uptake was found to be linearly dependent on temperature; decreasing with increasing temperature when tested in a 100% CO2 environment. Reactivity data for amine/bentonite particle with CO2 were presented and discussed. On the basis of the isothermal TGA results, reaction order and the value of activation energy have been obtained. These kinetic parameters are similar to those reported for MEA and DEA in aqueous solutions. The kinetic model was used to predict the fractional conversion at different temperature exhibiting good agreement with experimental data. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201214q [article] Performance and kinetics of a solid amine sorbent for carbon dioxide removal [texte imprimé] / Esmail R. Monazam, Auteur ; Lawrence J. Shadle, Auteur ; Ranjani Siriwardane, Auteur . - 2011 . - pp. 10989–10995. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 19 (Octobre 2011) . - pp. 10989–10995 Mots-clés : Kinetics  Solid  amine  sorbent Résumé : The kinetics of the reaction between CO2 and amine/bentonite particle were estimated over the range of 303–363 K from adsorption data obtained by TGA. The weight percent of amine, reaction temperature, and particle diameter were considered as experimental variables. The sorbent maximum or equilibrium CO2 uptake was found to be linearly dependent on temperature; decreasing with increasing temperature when tested in a 100% CO2 environment. Reactivity data for amine/bentonite particle with CO2 were presented and discussed. On the basis of the isothermal TGA results, reaction order and the value of activation energy have been obtained. These kinetic parameters are similar to those reported for MEA and DEA in aqueous solutions. The kinetic model was used to predict the fractional conversion at different temperature exhibiting good agreement with experimental data. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201214q