Documents disponibles écrits par cet auteur

Oxy - fuel combustion modeling / Stefan Hjartstam in Industrial & engineering chemistry research, Vol.51 N° 31 (Août 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol.51 N° 31 (Août 2012) . - pp. 10327–10337 Titre : Oxy - fuel combustion modeling : Performance of global reaction mechanisms Type de document : texte imprimé Auteurs : Stefan Hjartstam, Auteur ; Fredrik Normann, Auteur ; Klas Andersson, Auteur Année de publication : 2012 Article en page(s) : pp. 10327–10337 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Reaction  mechanism  Modeling  Combustion  Fuel Résumé : Three global reaction mechanisms derived for oxy-fuel combustion and one global reference mechanism are investigated and compared under gaseous oxy-fuel combustion conditions. The aim is to evaluate their prediction of major in-flame species and temperature by comparison with a detailed reaction mechanism (validated for oxy-fuel conditions) and experimental data. The evaluation is performed using a 1D plug flow reactor (PFR) method and 3D CFD calculations. Through the PFR calculations, it is found that the global mechanisms all predict a too early onset of fuel oxidation compared to the detailed mechanism. Furthermore, the global reference mechanism predicts gas concentrations more in line with the detailed mechanism than the oxy-fuel mechanisms, which yield incorrect reaction sequences. In the CFD analysis, significant differences in the predicted gas concentrations and temperature fields between the global mechanisms show that the choice of reaction mechanism strongly influences the results. In summary, the global reference mechanism is a preferable alternative to represent the combustion chemistry when modeling oxy-fuel combustion using CFD, if the use of a detailed reaction mechanism is prohibited due to computational limitations. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26234063 [article] Oxy - fuel combustion modeling : Performance of global reaction mechanisms [texte imprimé] / Stefan Hjartstam, Auteur ; Fredrik Normann, Auteur ; Klas Andersson, Auteur . - 2012 . - pp. 10327–10337. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol.51 N° 31 (Août 2012) . - pp. 10327–10337 Mots-clés : Reaction  mechanism  Modeling  Combustion  Fuel Résumé : Three global reaction mechanisms derived for oxy-fuel combustion and one global reference mechanism are investigated and compared under gaseous oxy-fuel combustion conditions. The aim is to evaluate their prediction of major in-flame species and temperature by comparison with a detailed reaction mechanism (validated for oxy-fuel conditions) and experimental data. The evaluation is performed using a 1D plug flow reactor (PFR) method and 3D CFD calculations. Through the PFR calculations, it is found that the global mechanisms all predict a too early onset of fuel oxidation compared to the detailed mechanism. Furthermore, the global reference mechanism predicts gas concentrations more in line with the detailed mechanism than the oxy-fuel mechanisms, which yield incorrect reaction sequences. In the CFD analysis, significant differences in the predicted gas concentrations and temperature fields between the global mechanisms show that the choice of reaction mechanism strongly influences the results. In summary, the global reference mechanism is a preferable alternative to represent the combustion chemistry when modeling oxy-fuel combustion using CFD, if the use of a detailed reaction mechanism is prohibited due to computational limitations. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26234063

Reburning in oxy - fuel combustion / Fredrik Normann in Industrial & engineering chemistry research, Vol. 49 N° 19 (Octobre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 19 (Octobre 2010) . - pp. 9088–9094 Titre : Reburning in oxy - fuel combustion : A parametric study of the combustion chemistry Type de document : texte imprimé Auteurs : Fredrik Normann, Auteur ; Klas Andersson, Auteur ; Filip Johnsson, Auteur Année de publication : 2010 Article en page(s) : pp. 9088–9094 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Nitrogen  oxides  Oxy  fuel  combustion Résumé : The present work investigates reburning reduction of nitrogen oxides in oxy-fuel combustion by means of a detailed reaction mechanism applied to a plug-flow reactor. Reburning reactions, which are known to convert NOx into N2, are of special interest in oxy-fuel combustion because of extensive recirculation of flue gases, including NOx, to the flame. Furthermore, the high concentration of carbon dioxide in oxy-fuel combustion is known to influence the radical pool (H/O/OH), which is critical to the combustion chemistry. In the present work, it is shown how the changes in the radical pool alter the nitrogen chemistry both directly and indirectly by influencing the formation and oxidation of hydrocarbon radicals. It is shown that reburning is more sensitive to the combustion temperature but is less affected by the combustion stoichiometry under oxy-fuel compared to air conditions. The main reasons are the impact of increased CO2 concentration on hydrocarbon oxidation and the increased importance of CH3 as a reactant in oxy-fuel combustion. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101192a [article] Reburning in oxy - fuel combustion : A parametric study of the combustion chemistry [texte imprimé] / Fredrik Normann, Auteur ; Klas Andersson, Auteur ; Filip Johnsson, Auteur . - 2010 . - pp. 9088–9094. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 19 (Octobre 2010) . - pp. 9088–9094 Mots-clés : Nitrogen  oxides  Oxy  fuel  combustion Résumé : The present work investigates reburning reduction of nitrogen oxides in oxy-fuel combustion by means of a detailed reaction mechanism applied to a plug-flow reactor. Reburning reactions, which are known to convert NOx into N2, are of special interest in oxy-fuel combustion because of extensive recirculation of flue gases, including NOx, to the flame. Furthermore, the high concentration of carbon dioxide in oxy-fuel combustion is known to influence the radical pool (H/O/OH), which is critical to the combustion chemistry. In the present work, it is shown how the changes in the radical pool alter the nitrogen chemistry both directly and indirectly by influencing the formation and oxidation of hydrocarbon radicals. It is shown that reburning is more sensitive to the combustion temperature but is less affected by the combustion stoichiometry under oxy-fuel compared to air conditions. The main reasons are the impact of increased CO2 concentration on hydrocarbon oxidation and the increased importance of CH3 as a reactant in oxy-fuel combustion. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101192a

SO3 formation under oxyfuel combustion conditions / Daniel Fleig in Industrial & engineering chemistry research, Vol. 50 N° 14 (Juillet 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 14 (Juillet 2011) . - pp. 8505–8514 Titre : SO3 formation under oxyfuel combustion conditions Type de document : texte imprimé Auteurs : Daniel Fleig, Auteur ; Klas Andersson, Auteur ; Fredrik Normann, Auteur Année de publication : 2011 Article en page(s) : pp. 8505–8514 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Oxyfuel  combustion Résumé : The sulfur chemistry in oxyfuel combustion systems has received growing attention lately. The formation of SO3 is of special concern, because of the elevated SO2 concentrations found in oxyfuel, compared to air-fuel conditions. The present study focuses on the gas-phase chemistry and examines the impact of different combustion parameters and atmospheres on the formation of SO3 in oxyfuel and air-fuel flames, using a detailed gas-phase model. The work also includes a summary of the presently available SOx data from experiments in laboratory and pilot-scale combustors. The reviewed experimental data, as well as the modeling results, show significantly increased SO3 concentrations in oxyfuel, compared to air-fuel conditions. The modeling results reveal a complex behavior of the SO3 formation, which is influenced by direct and indirect effects of the SO2, O2, NOx, and CO content in the flue gas. One of the main contributors to the increased SO3 concentration in oxyfuel, compared to air-fuel conditions, is the high concentration of SO2 in oxyfuel combustion. The modeling also shows that the stoichiometry, residence time, and flue-gas cooling rate are critical to the SO3 formation. Thus, in addition to the stoichiometry of the flame, the flue-gas recycling conditions are likely to influence the formation of SO3 in oxyfuel combustion. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2005274 [article] SO3 formation under oxyfuel combustion conditions [texte imprimé] / Daniel Fleig, Auteur ; Klas Andersson, Auteur ; Fredrik Normann, Auteur . - 2011 . - pp. 8505–8514. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 14 (Juillet 2011) . - pp. 8505–8514 Mots-clés : Oxyfuel  combustion Résumé : The sulfur chemistry in oxyfuel combustion systems has received growing attention lately. The formation of SO3 is of special concern, because of the elevated SO2 concentrations found in oxyfuel, compared to air-fuel conditions. The present study focuses on the gas-phase chemistry and examines the impact of different combustion parameters and atmospheres on the formation of SO3 in oxyfuel and air-fuel flames, using a detailed gas-phase model. The work also includes a summary of the presently available SOx data from experiments in laboratory and pilot-scale combustors. The reviewed experimental data, as well as the modeling results, show significantly increased SO3 concentrations in oxyfuel, compared to air-fuel conditions. The modeling results reveal a complex behavior of the SO3 formation, which is influenced by direct and indirect effects of the SO2, O2, NOx, and CO content in the flue gas. One of the main contributors to the increased SO3 concentration in oxyfuel, compared to air-fuel conditions, is the high concentration of SO2 in oxyfuel combustion. The modeling also shows that the stoichiometry, residence time, and flue-gas cooling rate are critical to the SO3 formation. Thus, in addition to the stoichiometry of the flame, the flue-gas recycling conditions are likely to influence the formation of SO3 in oxyfuel combustion. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2005274