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CO2 capture from simulated syngas via cyclic carbonation/calcination for a naturally occurring limestone / Robert T. Symonds in Industrial & engineering chemistry research, Vol. 48 N° 18 (Septembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8431–8440 Titre : CO2 capture from simulated syngas via cyclic carbonation/calcination for a naturally occurring limestone : pilot-plant testing Type de document : texte imprimé Auteurs : Robert T. Symonds, Auteur ; Dennis Y. Lu, Auteur ; Robin W. Hughes, Auteur Année de publication : 2010 Article en page(s) : pp. 8431–8440 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : CO2  capture  Fuidized  bed  reactor  system  Calcination  Cyclic  carbonation Résumé : Experiments were performed using a dual fluidized bed reactor system, operated in a batch mode, in order to investigate the effects of steam and simulated syngas on CO2 capture and sorbent conversion efficiency for a naturally occurring Polish calcitic limestone. In addition, the effect of high partial pressures of CO2 on the calcination process was examined using either oxygen-enriched air or oxy-fuel combustion in the calciner. As expected, calcination under oxy-fuel conditions resulted in decreased carbonation conversion due primarily to particle sintering and pore pluggage. On average there was a decrease in carbonation conversion of approximately 36.5 and 33.4% for carbonation with steam and steam/simulated syngas, respectively, compared to similar experiments using oxygen-enriched air. However, during the carbonation of the limestone with steam present in the feed gas, it was observed that the high CO2 capture efficiency period was significantly extended compared to carbonation with only CO2 present. This resulted in increased CaO conversion from approximately 16.1 to 29.7% for the initial carbonation cycle. A further increase in carbonation conversion, from 29.7 to 46.9%, was also observed when simulated syngas conditions (CO, H2) were used in the carbonator. Analysis of the outlet gases also confirmed that the calcined limestone catalyzes the water gas shift reaction, which we believe results in enhanced CO2 concentration levels at the grain surfaces of the sorbent. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900645x [article] CO2 capture from simulated syngas via cyclic carbonation/calcination for a naturally occurring limestone : pilot-plant testing [texte imprimé] / Robert T. Symonds, Auteur ; Dennis Y. Lu, Auteur ; Robin W. Hughes, Auteur . - 2010 . - pp. 8431–8440. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8431–8440 Mots-clés : CO2  capture  Fuidized  bed  reactor  system  Calcination  Cyclic  carbonation Résumé : Experiments were performed using a dual fluidized bed reactor system, operated in a batch mode, in order to investigate the effects of steam and simulated syngas on CO2 capture and sorbent conversion efficiency for a naturally occurring Polish calcitic limestone. In addition, the effect of high partial pressures of CO2 on the calcination process was examined using either oxygen-enriched air or oxy-fuel combustion in the calciner. As expected, calcination under oxy-fuel conditions resulted in decreased carbonation conversion due primarily to particle sintering and pore pluggage. On average there was a decrease in carbonation conversion of approximately 36.5 and 33.4% for carbonation with steam and steam/simulated syngas, respectively, compared to similar experiments using oxygen-enriched air. However, during the carbonation of the limestone with steam present in the feed gas, it was observed that the high CO2 capture efficiency period was significantly extended compared to carbonation with only CO2 present. This resulted in increased CaO conversion from approximately 16.1 to 29.7% for the initial carbonation cycle. A further increase in carbonation conversion, from 29.7 to 46.9%, was also observed when simulated syngas conditions (CO, H2) were used in the carbonator. Analysis of the outlet gases also confirmed that the calcined limestone catalyzes the water gas shift reaction, which we believe results in enhanced CO2 concentration levels at the grain surfaces of the sorbent. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900645x

Pilot - scale study of CO2 capture by CaO - based sorbents in the presence of steam and SO2 / Robert T. Symonds in Industrial & engineering chemistry research, Vol. 51 N° 21 (Mai 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 21 (Mai 2012) . - pp. 7177-7184 Titre : Pilot - scale study of CO2 capture by CaO - based sorbents in the presence of steam and SO2 Type de document : texte imprimé Auteurs : Robert T. Symonds, Auteur ; Dennis Y. Lu, Auteur ; Vasilije Manovic, Auteur Année de publication : 2012 Article en page(s) : pp. 7177-7184 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Water  vapor  Carbon  dioxide Résumé : Calcium looping cycles require an oxy-fired calciner burning coal for sorbent regeneration. Thus, in addition to O2 and CO2, the flue gases will include both steam and SO2, and similarly, carbonation of real flue-gases will occur in the presence of steam. However, to date, most research has been done without either of these two gaseous components present. Here, batch combustion experiments were performed in a pilot-scale fluidized-bed reactor to study the effects of steam and SO2 addition on CO2 capture by limestone-based sorbents calcined under oxygen-enriched air and oxy-fuel conditions. The initial fast kinetically controlled CO2 capture stage was dramatically reduced when the sorbent was calcined at realistic temperatures in the presence of SO2. This is attributed to both greater sintering due to higher local 2calcination temperatures required by high CO2 concentrations and CaSO4 formation. By contrast, steam in the synthetic flue gas during carbonation extended the initial, high-efficiency CO2 capture period compared with that observed during carbonation with dry synthetic flue gases. A comparison between pilot-scale fluidized-bed combustion (FBC) and thermogravimetric analysis (TGA) results showed that sorbent reactivity was considerably lower during pilot-scale FBC testing, as anticipated given the higher calcination temperatures employed in the FBC reactor and the presence of the other feed gases. The enhanced CO2 capture efficiency in FBC reactors with steam present was also confirmed by TGA tests. These results are important because they demonstrate how sorbent deactivation effects seen in realistic FBC calcium-looping operation can be successfully reduced by the presence of steam in the carbonator. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25948458 [article] Pilot - scale study of CO2 capture by CaO - based sorbents in the presence of steam and SO2 [texte imprimé] / Robert T. Symonds, Auteur ; Dennis Y. Lu, Auteur ; Vasilije Manovic, Auteur . - 2012 . - pp. 7177-7184. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 21 (Mai 2012) . - pp. 7177-7184 Mots-clés : Water  vapor  Carbon  dioxide Résumé : Calcium looping cycles require an oxy-fired calciner burning coal for sorbent regeneration. Thus, in addition to O2 and CO2, the flue gases will include both steam and SO2, and similarly, carbonation of real flue-gases will occur in the presence of steam. However, to date, most research has been done without either of these two gaseous components present. Here, batch combustion experiments were performed in a pilot-scale fluidized-bed reactor to study the effects of steam and SO2 addition on CO2 capture by limestone-based sorbents calcined under oxygen-enriched air and oxy-fuel conditions. The initial fast kinetically controlled CO2 capture stage was dramatically reduced when the sorbent was calcined at realistic temperatures in the presence of SO2. This is attributed to both greater sintering due to higher local 2calcination temperatures required by high CO2 concentrations and CaSO4 formation. By contrast, steam in the synthetic flue gas during carbonation extended the initial, high-efficiency CO2 capture period compared with that observed during carbonation with dry synthetic flue gases. A comparison between pilot-scale fluidized-bed combustion (FBC) and thermogravimetric analysis (TGA) results showed that sorbent reactivity was considerably lower during pilot-scale FBC testing, as anticipated given the higher calcination temperatures employed in the FBC reactor and the presence of the other feed gases. The enhanced CO2 capture efficiency in FBC reactors with steam present was also confirmed by TGA tests. These results are important because they demonstrate how sorbent deactivation effects seen in realistic FBC calcium-looping operation can be successfully reduced by the presence of steam in the carbonator. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25948458

Reactivation of CaO-based sorbents for CO2 capture / John Blamey in Industrial & engineering chemistry research, Vol. 50 N° 17 (Septembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 17 (Septembre 2011) . - pp. 10329–10334 Titre : Reactivation of CaO-based sorbents for CO2 capture : mechanism for the carbonation of Ca(OH)2 Type de document : texte imprimé Auteurs : John Blamey, Auteur ; Dennis Y. Lu, Auteur ; Paul S. Fennell, Auteur Année de publication : 2011 Article en page(s) : pp. 10329–10334 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Sorbents  CO2 Résumé : Calcium looping is an emerging technology for CO2 capture that uses a regenerable CaO-based sorbent. Here, a novel hydration-based reactivation strategy for spent sorbent, proposed by Industrial Research Limited of New Zealand, is investigated. They have called the process Ca(OH)2 “superheating” and suggested that Ca(OH)2 becomes more chemically stable under CO2, allowing release of steam at an elevated temperature (“superheated dehydration”). To investigate this, Ca(OH)2 powder and pellets and hydrated calcined limestone and dolomite have been heated in various different atmospheres in a thermogravimetric analyzer with a mass spectrometer performing online gas analysis of the off-gas. The “superheated dehydration” effect was observed for Ca(OH)2 pellets and hydrated calcined limestone, but not for Ca(OH)2 powder or hydrated calcined dolomite. These findings are consistent with a mechanism involving formation of an impermeable carbonate layer, which prevents H2O diffusion until rupture. The carbonate layer has a critical thickness that is not reached in the case of the Ca(OH)2 powder, but is in the case of the Ca(OH)2 pellets and hydrated calcined limestone. The network of MgO in the dolomitic particles results in CaO grains that are not large enough to accommodate the impermeable carbonate layer. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200912s [article] Reactivation of CaO-based sorbents for CO2 capture : mechanism for the carbonation of Ca(OH)2 [texte imprimé] / John Blamey, Auteur ; Dennis Y. Lu, Auteur ; Paul S. Fennell, Auteur . - 2011 . - pp. 10329–10334. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 17 (Septembre 2011) . - pp. 10329–10334 Mots-clés : Sorbents  CO2 Résumé : Calcium looping is an emerging technology for CO2 capture that uses a regenerable CaO-based sorbent. Here, a novel hydration-based reactivation strategy for spent sorbent, proposed by Industrial Research Limited of New Zealand, is investigated. They have called the process Ca(OH)2 “superheating” and suggested that Ca(OH)2 becomes more chemically stable under CO2, allowing release of steam at an elevated temperature (“superheated dehydration”). To investigate this, Ca(OH)2 powder and pellets and hydrated calcined limestone and dolomite have been heated in various different atmospheres in a thermogravimetric analyzer with a mass spectrometer performing online gas analysis of the off-gas. The “superheated dehydration” effect was observed for Ca(OH)2 pellets and hydrated calcined limestone, but not for Ca(OH)2 powder or hydrated calcined dolomite. These findings are consistent with a mechanism involving formation of an impermeable carbonate layer, which prevents H2O diffusion until rupture. The carbonate layer has a critical thickness that is not reached in the case of the Ca(OH)2 powder, but is in the case of the Ca(OH)2 pellets and hydrated calcined limestone. The network of MgO in the dolomitic particles results in CaO grains that are not large enough to accommodate the impermeable carbonate layer. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200912s