Accurate high - temperature reaction networks for alternative fuels / Kevin M. Van Geem in Industrial & engineering chemistry research, Vol. 49 N° 21 (Novembre 2010)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10399-10420 Titre : Accurate high - temperature reaction networks for alternative fuels : Butanol isomers Type de document : texte imprimé Auteurs : Kevin M. Van Geem, Auteur ; Steven P. Pyl, Auteur ; Guy B. Marin, Auteur Année de publication : 2011 Article en page(s) : pp. 10399-10420 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : High temperature Isomers Résumé : Oxygenated hydrocarbons, particularly alcohol compounds, are being studied extensively as alternatives and additives to conventional fuels due to their propensity of decreasing soot formation and improving the octane number of gasoline. However, oxygenated fuels also increase the production of toxic byproducts, such as formaldehyde. To gain a better understanding of the oxygenated functional group's influence on combustion properties-e.g., ignition delay at temperatures above the negative temperature coefficient regime, and the rate of benzene production, which is the common precursor to soot formation-a detailed pressure-dependent reaction network for n-butanol, sec-butanol, and tert-butanol consisting of 281 species and 3608 reactions is presented. The reaction network is validated against shock tube ignition delays and doped methane flame concentration profiles reported previously in the literature, in addition to newly acquired pyrolysis data. Good agreement between simulated and experimental data is achieved in all cases. Flux and sensitivity analyses for each set of experiments have been performed, and high-pressure-limit reaction rate coefficients for important pathways, e.g., the dehydration reactions of the butanol isomers, have been computed using statistical mechanics and quantum chemistry. The different alcohol decomposition pathways, i.e., the pathways from primary, secondary, and tertiary alcohols, are discussed. Furthermore, comparisons between ethanol and n-butanol, two primary alcohols, are presented, as they relate to ignition delay. ISSN : 0888-5885 En ligne : http://www.mendeley.com/research/accurate-hightemperature-reaction-networks-alte [...] [article] Accurate high - temperature reaction networks for alternative fuels : Butanol isomers [texte imprimé] / Kevin M. Van Geem, Auteur ; Steven P. Pyl, Auteur ; Guy B. Marin, Auteur . - 2011 . - pp. 10399-10420. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10399-10420 Mots-clés : High temperature Isomers Résumé : Oxygenated hydrocarbons, particularly alcohol compounds, are being studied extensively as alternatives and additives to conventional fuels due to their propensity of decreasing soot formation and improving the octane number of gasoline. However, oxygenated fuels also increase the production of toxic byproducts, such as formaldehyde. To gain a better understanding of the oxygenated functional group's influence on combustion properties-e.g., ignition delay at temperatures above the negative temperature coefficient regime, and the rate of benzene production, which is the common precursor to soot formation-a detailed pressure-dependent reaction network for n-butanol, sec-butanol, and tert-butanol consisting of 281 species and 3608 reactions is presented. The reaction network is validated against shock tube ignition delays and doped methane flame concentration profiles reported previously in the literature, in addition to newly acquired pyrolysis data. Good agreement between simulated and experimental data is achieved in all cases. Flux and sensitivity analyses for each set of experiments have been performed, and high-pressure-limit reaction rate coefficients for important pathways, e.g., the dehydration reactions of the butanol isomers, have been computed using statistical mechanics and quantum chemistry. The different alcohol decomposition pathways, i.e., the pathways from primary, secondary, and tertiary alcohols, are discussed. Furthermore, comparisons between ethanol and n-butanol, two primary alcohols, are presented, as they relate to ignition delay. ISSN : 0888-5885 En ligne : http://www.mendeley.com/research/accurate-hightemperature-reaction-networks-alte [...]

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Coke formation in the transfer line exchanger during steam cracking of hydrocarbons / Kevin M. Van Geem in Industrial & engineering chemistry research, Vol. 48 N° 23 (Décembre 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N° 23 (Décembre 2009) . - pp. 10343–10358 Titre : Coke formation in the transfer line exchanger during steam cracking of hydrocarbons Type de document : texte imprimé Auteurs : Kevin M. Van Geem, Auteur ; Inge Dhuyvetter, Auteur ; Serge Prokopiev, Auteur Année de publication : 2010 Article en page(s) : pp. 10343–10358 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Coke Formation--Transfer--Line Exchanger--during Steam--Cracking --Hydrocarbons Résumé : Coke formation under transfer line exchanger conditions, that is, at temperatures from 623 to 873 K and atmospheric pressure, is studied in an electrobalance setup. The coking rate is initially very high (catalytic coking) and drops after a few hours to a constant value. At the studied conditions the observed coking behavior on 15Mo3 alloy pigs can be explained via a catalytic mechanism only, and contributions of the free-radical mechanism and the condensation mechanism are insignificant. Experiments with ethane and naphtha steam cracking effluents and with well-defined reaction mixtures show that the coking rate is independent of the partial pressure of ethene (0−2.7 × 104 Pa), ortho-xylene (0−1.0 × 104 Pa), heavy aromatic hydrocarbons (0−3.0 × 102 Pa), and also 1,3-butadiene (0−2.7 × 104 Pa). The rate of coke deposition depends only on the temperature and the ratio of the partial pressures of water to dihydrogen. The activation energy for initial coke formation was estimated to be ∼90 kJ/mol, a value close to the experimentally determined diffusion energy of carbon in iron. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900124z [article] Coke formation in the transfer line exchanger during steam cracking of hydrocarbons [texte imprimé] / Kevin M. Van Geem, Auteur ; Inge Dhuyvetter, Auteur ; Serge Prokopiev, Auteur . - 2010 . - pp. 10343–10358. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 23 (Décembre 2009) . - pp. 10343–10358 Mots-clés : Coke Formation--Transfer--Line Exchanger--during Steam--Cracking --Hydrocarbons Résumé : Coke formation under transfer line exchanger conditions, that is, at temperatures from 623 to 873 K and atmospheric pressure, is studied in an electrobalance setup. The coking rate is initially very high (catalytic coking) and drops after a few hours to a constant value. At the studied conditions the observed coking behavior on 15Mo3 alloy pigs can be explained via a catalytic mechanism only, and contributions of the free-radical mechanism and the condensation mechanism are insignificant. Experiments with ethane and naphtha steam cracking effluents and with well-defined reaction mixtures show that the coking rate is independent of the partial pressure of ethene (0−2.7 × 104 Pa), ortho-xylene (0−1.0 × 104 Pa), heavy aromatic hydrocarbons (0−3.0 × 102 Pa), and also 1,3-butadiene (0−2.7 × 104 Pa). The rate of coke deposition depends only on the temperature and the ratio of the partial pressures of water to dihydrogen. The activation energy for initial coke formation was estimated to be ∼90 kJ/mol, a value close to the experimentally determined diffusion energy of carbon in iron. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900124z

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Modeling the composition of crude oil fractions using constrained homologous series / Steven P. Pyl in Industrial & engineering chemistry research, Vol. 50 N° 18 (Septembre 2011)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 50 N° 18 (Septembre 2011) . - pp. 10850-10858 Titre : Modeling the composition of crude oil fractions using constrained homologous series Type de document : texte imprimé Auteurs : Steven P. Pyl, Auteur ; Zhen Hou, Auteur ; Kevin M. Van Geem, Auteur Année de publication : 2011 Article en page(s) : pp. 10850-10858 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Crude oil Modeling Résumé : Composition anodeling using coastrained homologous series permits the derivation of the detailed composition of complex mixtures starting from a limited set of mixture bulk properties. By imposing various constraints, the number of unknowns is drastically reduced. Probability density functions are imposed on both the carbon number distribution in each homologous series of components and on the structural attribute distributions. Validation, based on detailed compositional information, shows that the use of gamma distributions to constrain the mixture composition results in an adequate approximation of the experimentally measured composition. The latter was obtained for two middle distillates and a heavy gas oil using advanced analytical techniques. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24523902 [article] Modeling the composition of crude oil fractions using constrained homologous series [texte imprimé] / Steven P. Pyl, Auteur ; Zhen Hou, Auteur ; Kevin M. Van Geem, Auteur . - 2011 . - pp. 10850-10858. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 18 (Septembre 2011) . - pp. 10850-10858 Mots-clés : Crude oil Modeling Résumé : Composition anodeling using coastrained homologous series permits the derivation of the detailed composition of complex mixtures starting from a limited set of mixture bulk properties. By imposing various constraints, the number of unknowns is drastically reduced. Probability density functions are imposed on both the carbon number distribution in each homologous series of components and on the structural attribute distributions. Validation, based on detailed compositional information, shows that the use of gamma distributions to constrain the mixture composition results in an adequate approximation of the experimentally measured composition. The latter was obtained for two middle distillates and a heavy gas oil using advanced analytical techniques. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24523902

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