Hybrid cycles to purify concentrated feeds containing a strongly adsorbed impurity with a nonlinear isotherm / Pradeep K. Sharma in Industrial & engineering chemistry research, Vol. 48 N° 13 (Juillet 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. 6405–6416 Titre : Hybrid cycles to purify concentrated feeds containing a strongly adsorbed impurity with a nonlinear isotherm : the PSA−TSA supercycle Type de document : texte imprimé Auteurs : Pradeep K. Sharma, Auteur ; Phillip C. Wankat, Auteur Année de publication : 2009 Article en page(s) : pp. 6405–6416 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Adsorption process Non- or weakly adsorbing gas PSA−  TSA supercycle Résumé : A new adsorption process is developed to remove a strongly adsorbing gaseous impurity that has a very nonlinear isotherm from a non- or weakly adsorbing gas. This process, a number of pressure-swing cycles with low purge ratios followed by thermal regeneration, is called a PSA−TSA supercycle because it consists of thermal cycles on top of PSA cycles. The PSA cycles never reach cyclic steady state by themselves, although the supercycle does reach cyclic steady state. A water/nitrogen mixture with zeolite 13X is taken as model system because water exhibits strongly nonlinear adsorption characteristics. At low feed concentrations (1000 ppm water), PSA works well and is the preferred method. At intermediate feed concentrations (4000 ppm water), TSA is the preferred method. The PSA−TSA supercycle is better than PSA and TSA in handling high solute concentrations in the feed (40 000 ppm water) and producing high-purity product (1 ppm water). PSA fails to meet this purity, and TSA has low productivity. The new hybrid cycle is promising for highly nonlinear systems with high solute concentrations in the feed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801661w [article] Hybrid cycles to purify concentrated feeds containing a strongly adsorbed impurity with a nonlinear isotherm : the PSA−TSA supercycle [texte imprimé] / Pradeep K. Sharma, Auteur ; Phillip C. Wankat, Auteur . - 2009 . - pp. 6405–6416. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. 6405–6416 Mots-clés : Adsorption process Non- or weakly adsorbing gas PSA−  TSA supercycle Résumé : A new adsorption process is developed to remove a strongly adsorbing gaseous impurity that has a very nonlinear isotherm from a non- or weakly adsorbing gas. This process, a number of pressure-swing cycles with low purge ratios followed by thermal regeneration, is called a PSA−TSA supercycle because it consists of thermal cycles on top of PSA cycles. The PSA cycles never reach cyclic steady state by themselves, although the supercycle does reach cyclic steady state. A water/nitrogen mixture with zeolite 13X is taken as model system because water exhibits strongly nonlinear adsorption characteristics. At low feed concentrations (1000 ppm water), PSA works well and is the preferred method. At intermediate feed concentrations (4000 ppm water), TSA is the preferred method. The PSA−TSA supercycle is better than PSA and TSA in handling high solute concentrations in the feed (40 000 ppm water) and producing high-purity product (1 ppm water). PSA fails to meet this purity, and TSA has low productivity. The new hybrid cycle is promising for highly nonlinear systems with high solute concentrations in the feed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801661w

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Solvent recovery by steamless temperature swing carbon adsorption processes / Pradeep K. Sharma in Industrial & engineering chemistry research, Vol. 49 N° 22 (Novembre 2010)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11602–11613 Titre : Solvent recovery by steamless temperature swing carbon adsorption processes Type de document : texte imprimé Auteurs : Pradeep K. Sharma, Auteur ; Phillip C. Wankat, Auteur Année de publication : 2011 Article en page(s) : pp. 11602–11613 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Solvent Adsorption Processes Résumé : Adsorption with activated carbon followed by regeneration with steam is the most common technique for solvent recovery from gas streams. The resulting steam−solvent gaseous mixture when condensed can result in either two separate layers (immiscible) or a single liquid phase (miscible or miscible with an azeotrope). For miscible systems that form azeotropes, the downstream distillation system can easily be more expensive than the adsorbers. An alternative is to use hot nitrogen instead of steam for desorption. By adding a short oxygen/water removal step to the adsorption cycle, the need for distillation is avoided. The model system studied for the azeotropic case was recovery of 0.5 mol % isopropanol (IPA) from air with hot nitrogen for regeneration. Since the nitrogen cost dominates, nitrogen should be recovered and recycled as much as possible. Two- and four-bed adsorption schemes were studied, and the four-bed system, which recovers almost all of the nitrogen, was best. A preliminary total cost comparison showed that solvent recovery of IPA with steam regeneration has total costs that are 14% higher than for IPA recovery with hot nitrogen regeneration if the nitrogen is recovered and recycled. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1008019 [article] Solvent recovery by steamless temperature swing carbon adsorption processes [texte imprimé] / Pradeep K. Sharma, Auteur ; Phillip C. Wankat, Auteur . - 2011 . - pp. 11602–11613. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11602–11613 Mots-clés : Solvent Adsorption Processes Résumé : Adsorption with activated carbon followed by regeneration with steam is the most common technique for solvent recovery from gas streams. The resulting steam−solvent gaseous mixture when condensed can result in either two separate layers (immiscible) or a single liquid phase (miscible or miscible with an azeotrope). For miscible systems that form azeotropes, the downstream distillation system can easily be more expensive than the adsorbers. An alternative is to use hot nitrogen instead of steam for desorption. By adding a short oxygen/water removal step to the adsorption cycle, the need for distillation is avoided. The model system studied for the azeotropic case was recovery of 0.5 mol % isopropanol (IPA) from air with hot nitrogen for regeneration. Since the nitrogen cost dominates, nitrogen should be recovered and recycled as much as possible. Two- and four-bed adsorption schemes were studied, and the four-bed system, which recovers almost all of the nitrogen, was best. A preliminary total cost comparison showed that solvent recovery of IPA with steam regeneration has total costs that are 14% higher than for IPA recovery with hot nitrogen regeneration if the nitrogen is recovered and recycled. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1008019

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