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Equilibrium theory analysis of a pressure swing adsorption cycle utilizing a favorable langmuir isotherm / D. Jason Owens in Industrial & engineering chemistry research, Vol. 51 N° 41 (Octobre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 41 (Octobre 2012) . - pp. 13454–13462 Titre : Equilibrium theory analysis of a pressure swing adsorption cycle utilizing a favorable langmuir isotherm : Approach to periodic behavior Type de document : texte imprimé Auteurs : D. Jason Owens, Auteur ; Armin D. Ebner, Auteur ; James A. Ritter, Auteur Année de publication : 2012 Article en page(s) : pp. 13454–13462 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Analyse  Adsorption  Isotherm Résumé : An isothermal equilibrium theory analysis of a simple two-step pressure-swing adsorption (PSA) process utilizing an adsorbate–adsorbent system that exhibits a favorable Langmuir isotherm was carried out. Analytic expressions, either simple or recursive, were obtained that describe process operation and process performance during the approach to periodicity. These expressions are a function of cycle number and various process parameters. A recursive relationship for the dimensionless penetration depth for each cycle was determined and, although no closed form is readily available (and likely does not exist), the recursive relationship is easily applicable in any spreadsheet program. All other expressions were derived as functions of the penetration depth, thus lending a full analysis to the capabilities of a spreadsheet program. The analysis is primarily focused on the case of no breakthrough, because of the fact that breakthrough forces the system prematurely to periodicity and is therefore trivial for the approach analysis. The resulting expressions were used to examine process performance upon the approach to periodicity for several hypothetical systems, and the effects of various parameters on the number of cycles required to reach a periodic, or virtually periodic, state were examined. From an understanding or educational point of view, this analysis clearly shows how the so-called “heel in the bed”, i.e., the adsorbate loading remaining in the bed after the end-of-purge step, forms on the very first cycle and continues to increase cycle after cycle until periodicity is attained. This buildup of the heel in the bed is characteristic of all PSA processes, with a slower buildup resulting from a more nonlinear isotherm or a smaller purge-to-feed ratio. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie301395y [article] Equilibrium theory analysis of a pressure swing adsorption cycle utilizing a favorable langmuir isotherm : Approach to periodic behavior [texte imprimé] / D. Jason Owens, Auteur ; Armin D. Ebner, Auteur ; James A. Ritter, Auteur . - 2012 . - pp. 13454–13462. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 41 (Octobre 2012) . - pp. 13454–13462 Mots-clés : Analyse  Adsorption  Isotherm Résumé : An isothermal equilibrium theory analysis of a simple two-step pressure-swing adsorption (PSA) process utilizing an adsorbate–adsorbent system that exhibits a favorable Langmuir isotherm was carried out. Analytic expressions, either simple or recursive, were obtained that describe process operation and process performance during the approach to periodicity. These expressions are a function of cycle number and various process parameters. A recursive relationship for the dimensionless penetration depth for each cycle was determined and, although no closed form is readily available (and likely does not exist), the recursive relationship is easily applicable in any spreadsheet program. All other expressions were derived as functions of the penetration depth, thus lending a full analysis to the capabilities of a spreadsheet program. The analysis is primarily focused on the case of no breakthrough, because of the fact that breakthrough forces the system prematurely to periodicity and is therefore trivial for the approach analysis. The resulting expressions were used to examine process performance upon the approach to periodicity for several hypothetical systems, and the effects of various parameters on the number of cycles required to reach a periodic, or virtually periodic, state were examined. From an understanding or educational point of view, this analysis clearly shows how the so-called “heel in the bed”, i.e., the adsorbate loading remaining in the bed after the end-of-purge step, forms on the very first cycle and continues to increase cycle after cycle until periodicity is attained. This buildup of the heel in the bed is characteristic of all PSA processes, with a slower buildup resulting from a more nonlinear isotherm or a smaller purge-to-feed ratio. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie301395y

New approach for modeling hybrid pressure swing adsorption – distillation processes / James A. Ritter in Industrial & engineering chemistry research, Vol. 51 N° 27 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 27 (Juillet 2012) . - pp. 9343-9355 Titre : New approach for modeling hybrid pressure swing adsorption – distillation processes Type de document : texte imprimé Auteurs : James A. Ritter, Auteur ; Fan Wu, Auteur ; Armin D. Ebner, Auteur Année de publication : 2012 Article en page(s) : pp. 9343-9355 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Distillation  Pressure  swing  adsorption  Modeling Résumé : A new methodology for modeling hybrid pressure swing adsorption (PSA)―distillation processes has been developed. This new approach involves two parts. Part I determines if energy savings are possible. It can be done easily with sufficient knowledge of distillation process design, but with only minimal knowledge of PSA process design. Part I is carried out using a distillation process simulator such as Chemsep to model a distillation column connected to a PSA unit that is treated as a "black box" with an assumed process performance. In this way, a hybrid PSA―distillation process can be analyzed simply by performing mass balances around these units and running Chemsep to determine if energy savings are possible compared to a reference (commercial) process. Once an energy savings hybrid "black box" PSA―distillation process is found in part I, part II determines if an "actual" PSA process exists that mimics its performance. Part II is carried out using a rigorous PSA process simulator such as Adsim from AspenTech; thus, it requires significant knowledge of PSA process design. The outcome of part II is a hybrid PSA―distillation process that has the potential to be more energy efficient than the reference process. This new approach was successfully demonstrated using the commercial hybrid PSA―distillation process developed for fuel grade ethanol production as the reference case. This two-part analysis found several, more energy efficient designs than the reference case. All of them had proportionately reduced internal vapor and liquid flows in the distillation column, a direct effect of reducing condenser or reboiler duty. These results illustrated that the new methodology should be very useful for quickly accessing the utility of hybrid PSA―distillation processes for a variety of other applications, with many possibilities for achieving significant energy savings and/or throughput debottlenecking. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26132271 [article] New approach for modeling hybrid pressure swing adsorption – distillation processes [texte imprimé] / James A. Ritter, Auteur ; Fan Wu, Auteur ; Armin D. Ebner, Auteur . - 2012 . - pp. 9343-9355. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 27 (Juillet 2012) . - pp. 9343-9355 Mots-clés : Distillation  Pressure  swing  adsorption  Modeling Résumé : A new methodology for modeling hybrid pressure swing adsorption (PSA)―distillation processes has been developed. This new approach involves two parts. Part I determines if energy savings are possible. It can be done easily with sufficient knowledge of distillation process design, but with only minimal knowledge of PSA process design. Part I is carried out using a distillation process simulator such as Chemsep to model a distillation column connected to a PSA unit that is treated as a "black box" with an assumed process performance. In this way, a hybrid PSA―distillation process can be analyzed simply by performing mass balances around these units and running Chemsep to determine if energy savings are possible compared to a reference (commercial) process. Once an energy savings hybrid "black box" PSA―distillation process is found in part I, part II determines if an "actual" PSA process exists that mimics its performance. Part II is carried out using a rigorous PSA process simulator such as Adsim from AspenTech; thus, it requires significant knowledge of PSA process design. The outcome of part II is a hybrid PSA―distillation process that has the potential to be more energy efficient than the reference process. This new approach was successfully demonstrated using the commercial hybrid PSA―distillation process developed for fuel grade ethanol production as the reference case. This two-part analysis found several, more energy efficient designs than the reference case. All of them had proportionately reduced internal vapor and liquid flows in the distillation column, a direct effect of reducing condenser or reboiler duty. These results illustrated that the new methodology should be very useful for quickly accessing the utility of hybrid PSA―distillation processes for a variety of other applications, with many possibilities for achieving significant energy savings and/or throughput debottlenecking. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26132271

Temperature dependence of the nonequilibrium kinetic model that describes the adsorption and desorption behavior of CO2 in K-promoted HTlc / Hai Du in Industrial & engineering chemistry research, Vol. 49 N° 7 (Avril 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 7 (Avril 2010) . - pp. 3328–3336 Titre : Temperature dependence of the nonequilibrium kinetic model that describes the adsorption and desorption behavior of CO2 in K-promoted HTlc Type de document : texte imprimé Auteurs : Hai Du, Auteur ; Armin D. Ebner, Auteur ; James A. Ritter, Auteur Année de publication : 2010 Article en page(s) : pp. 3328–3336 Note générale : Industrial Chemestry Langues : Anglais (eng) Mots-clés : Temperature  Kinetic  Nonequilibrium  Mod  Behavior  CO2  K-Promoted  HTlc Résumé : A nonequilibrium kinetic model developed previously by the authors to describe the reversible adsorption and desorption behavior of CO2 in a K-promoted hydrotalcite-like compound (HTlc) was extended to account for temperature effects. This model involves three steps and four phases that reversibly undergo adsorption or reaction with CO2 in the structure. The model parameters were obtained by fitting it to experimental adsorption and desorption cycling data carried out with in-house-synthesized K-promoted HTlc at 11 temperatures ranging from 300 to 500 °C. A single adsorption (in CO2 at 1 atm) and desorption (in He at 1 atm) cycle having a 700 min half-cycle time was obtained at each temperature and fitted successfully to the model. Then, using the same set of parameters, the model was used to successfully predict similar shorter cycle time experiments carried out with a 60 min half-cycle time for eight cycles at each temperature. For both the long and short cycle time data, the model captured all three kinetic regimes, the absolute CO2 capacity, the CO2 working capacity, the periodic behavior, and their temperature dependence. The deviations that did occur between the model and experiments were generally due to irreversible losses observed with the short cycle time runs at 480 and 500 °C that could not be predicted by the model; they were thus considered to be inconsequential. Both the model and experiments showed that temperature played an important role, with optimum temperatures being in the 380−420 °C range. Overall, this new model further validated that CO2 uptake and release in K-promoted HTlc is associated with a combination of completely reversible adsorption, diffusion, and reaction phenomena, through a three-step, four-phase process that has a strong temperature dependence. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901210y [article] Temperature dependence of the nonequilibrium kinetic model that describes the adsorption and desorption behavior of CO2 in K-promoted HTlc [texte imprimé] / Hai Du, Auteur ; Armin D. Ebner, Auteur ; James A. Ritter, Auteur . - 2010 . - pp. 3328–3336. Industrial Chemestry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 7 (Avril 2010) . - pp. 3328–3336 Mots-clés : Temperature  Kinetic  Nonequilibrium  Mod  Behavior  CO2  K-Promoted  HTlc Résumé : A nonequilibrium kinetic model developed previously by the authors to describe the reversible adsorption and desorption behavior of CO2 in a K-promoted hydrotalcite-like compound (HTlc) was extended to account for temperature effects. This model involves three steps and four phases that reversibly undergo adsorption or reaction with CO2 in the structure. The model parameters were obtained by fitting it to experimental adsorption and desorption cycling data carried out with in-house-synthesized K-promoted HTlc at 11 temperatures ranging from 300 to 500 °C. A single adsorption (in CO2 at 1 atm) and desorption (in He at 1 atm) cycle having a 700 min half-cycle time was obtained at each temperature and fitted successfully to the model. Then, using the same set of parameters, the model was used to successfully predict similar shorter cycle time experiments carried out with a 60 min half-cycle time for eight cycles at each temperature. For both the long and short cycle time data, the model captured all three kinetic regimes, the absolute CO2 capacity, the CO2 working capacity, the periodic behavior, and their temperature dependence. The deviations that did occur between the model and experiments were generally due to irreversible losses observed with the short cycle time runs at 480 and 500 °C that could not be predicted by the model; they were thus considered to be inconsequential. Both the model and experiments showed that temperature played an important role, with optimum temperatures being in the 380−420 °C range. Overall, this new model further validated that CO2 uptake and release in K-promoted HTlc is associated with a combination of completely reversible adsorption, diffusion, and reaction phenomena, through a three-step, four-phase process that has a strong temperature dependence. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901210y