Documents disponibles écrits par cet auteur

Adapting process unit relations in experimental data weighting procedures / Ngigi, Geoffrey K. in Industrial & engineering chemistry research, Vol. 49 N° 4 (Fevrier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1975–1981 Titre : Adapting process unit relations in experimental data weighting procedures : a phase equilibrium case study Type de document : texte imprimé Auteurs : Ngigi, Geoffrey K., Auteur ; Diane Hildebrandt, Auteur ; David Glasser, Auteur Année de publication : 2010 Article en page(s) : pp 1975–1981 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Weighting  method  Phase  equilibrium. Résumé : A data weighting method derived from analysis of the distillation column design relation(s) is used on several experimental vapor−liquid equilibrium (VLE) sets of data for estimating the interaction pair parameters of two local-composition models (NRTL and Wilson). It is shown that process equations can provide insights on the requisite objective function(s) to obtain parameters more suited to a particular design intent. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801987j [article] Adapting process unit relations in experimental data weighting procedures : a phase equilibrium case study [texte imprimé] / Ngigi, Geoffrey K., Auteur ; Diane Hildebrandt, Auteur ; David Glasser, Auteur . - 2010 . - pp 1975–1981. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1975–1981 Mots-clés : Weighting  method  Phase  equilibrium. Résumé : A data weighting method derived from analysis of the distillation column design relation(s) is used on several experimental vapor−liquid equilibrium (VLE) sets of data for estimating the interaction pair parameters of two local-composition models (NRTL and Wilson). It is shown that process equations can provide insights on the requisite objective function(s) to obtain parameters more suited to a particular design intent. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801987j

Complex column design by application of column profile map techniques / Simon T. Holland in Industrial & engineering chemistry research, Vol. 49 N° 1 (Janvier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 1 (Janvier 2010) . - pp. 327–349 Titre : Complex column design by application of column profile map techniques : sharp-split petlyuk column design Type de document : texte imprimé Auteurs : Simon T. Holland, Auteur ; Ronald Abbas, Auteur ; Diane Hildebrandt, Auteur Année de publication : 2010 Article en page(s) : pp. 327–349 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Complex--Column--Design--Application--Column  Profile--Map  Techniques--Sharp-Split--Petlyuk--Column  Design Résumé : Currently employed short-cut design techniques have a tendency to be configuration-specific. Few can be applied to complex distillation configurations. In this work, we will demonstrate, in detail, the use of column profile maps (CPMs) for the comprehensive analysis and design of complex distillation systems by applying the CPM technique to the design of the fully thermally coupled (Petlyuk) distillation column at sharp-split conditions. It is shown that, for set product composition specifications and a set reflux ratio, only a small region of key parameters (vapor and liquid split ratios) result in feasible separations. These results—and, hence, the CPM design procedure—are validated by the work of Halvorsen in his 2001 Ph.D. thesis. It is also shown that the minimum reflux solution can be found using this methodology. The results are valid for all zeotropic separation syntheses. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801752r [article] Complex column design by application of column profile map techniques : sharp-split petlyuk column design [texte imprimé] / Simon T. Holland, Auteur ; Ronald Abbas, Auteur ; Diane Hildebrandt, Auteur . - 2010 . - pp. 327–349. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 1 (Janvier 2010) . - pp. 327–349 Mots-clés : Complex--Column--Design--Application--Column  Profile--Map  Techniques--Sharp-Split--Petlyuk--Column  Design Résumé : Currently employed short-cut design techniques have a tendency to be configuration-specific. Few can be applied to complex distillation configurations. In this work, we will demonstrate, in detail, the use of column profile maps (CPMs) for the comprehensive analysis and design of complex distillation systems by applying the CPM technique to the design of the fully thermally coupled (Petlyuk) distillation column at sharp-split conditions. It is shown that, for set product composition specifications and a set reflux ratio, only a small region of key parameters (vapor and liquid split ratios) result in feasible separations. These results—and, hence, the CPM design procedure—are validated by the work of Halvorsen in his 2001 Ph.D. thesis. It is also shown that the minimum reflux solution can be found using this methodology. The results are valid for all zeotropic separation syntheses. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801752r

Efficient combustion / Baraka Celestin Sempuga in Industrial & engineering chemistry research, Vol. 51 N° 26 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 9061-9077 Titre : Efficient combustion : A process synthesis approach to improve the efficiency of coal - fired power stations Type de document : texte imprimé Auteurs : Baraka Celestin Sempuga, Auteur ; Bilal Patel, Auteur ; Diane Hildebrandt, Auteur Année de publication : 2012 Article en page(s) : pp. 9061-9077 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Coal  Combustion Résumé : Much of our energy reserves are locked in the chemical potential of chemicals such as fossil fuels. The majority of CO2 emissions caused by human activities come from the combustion of these fuels. Typically, the fuel is burned with oxygen (air), and heat is released. This heat is then used to drive power cycles to produce, for example, electricity in a power plant or motion in the motor car engine. Often, the performance of these processes is assessed in term of thermal efficiency (ηth), which considers how much of the energy released in the combustion process is turned into work. This is not a good representation of how efficient the process is, however, as an idealized Carnot engine, which takes heat from a heat source at a temperature TH and rejects heat to a heat sink at the reference temperature To = 298.15 K, is reversible and thus takes all of the work potential (exergy) of heat and converts this to work. Thus, the Carnot engine might have only 40% efficiency in terms of converting heat to work (ηth), but because it is fully reversible, it generates no entropy, and therefore, it is 100% efficient in terms of recovering the work potential of heat. However, there is a much more fundamental efficiency that should be considered, namely, how much of the chemical potential of the fuel is turned into work. When combustion processes are considered in this way, it becomes clear that some of the major inefficiencies are in the chemical transformations that produce heat, rather than in the power cycles that convert heat to work. A very important question remains: Is it possible to do these transformations more efficiently and thereby conserve the work potential or chemical potential in fuel? This article shows, from a fundamental thermodynamic analysis, that it is not possible to combust carbon-based materials efficiently, that is, that the process of combustion of carbon-based materials is irreversible and that a considerable amount of the chemical potential of the fuel is lost during the combustion process. However, other substances or chemistries are explored in this work, and it is shown that some of these have the potential for more reversible combustion. These options are explored, and their potential implementation is examined by considering a coal-based power plant as an example. In particular, it is shown that CO2 emissions could be significantly reduced by using different chemical pathways to do the combustion and by combining power and chemical production. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26107463 [article] Efficient combustion : A process synthesis approach to improve the efficiency of coal - fired power stations [texte imprimé] / Baraka Celestin Sempuga, Auteur ; Bilal Patel, Auteur ; Diane Hildebrandt, Auteur . - 2012 . - pp. 9061-9077. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 9061-9077 Mots-clés : Coal  Combustion Résumé : Much of our energy reserves are locked in the chemical potential of chemicals such as fossil fuels. The majority of CO2 emissions caused by human activities come from the combustion of these fuels. Typically, the fuel is burned with oxygen (air), and heat is released. This heat is then used to drive power cycles to produce, for example, electricity in a power plant or motion in the motor car engine. Often, the performance of these processes is assessed in term of thermal efficiency (ηth), which considers how much of the energy released in the combustion process is turned into work. This is not a good representation of how efficient the process is, however, as an idealized Carnot engine, which takes heat from a heat source at a temperature TH and rejects heat to a heat sink at the reference temperature To = 298.15 K, is reversible and thus takes all of the work potential (exergy) of heat and converts this to work. Thus, the Carnot engine might have only 40% efficiency in terms of converting heat to work (ηth), but because it is fully reversible, it generates no entropy, and therefore, it is 100% efficient in terms of recovering the work potential of heat. However, there is a much more fundamental efficiency that should be considered, namely, how much of the chemical potential of the fuel is turned into work. When combustion processes are considered in this way, it becomes clear that some of the major inefficiencies are in the chemical transformations that produce heat, rather than in the power cycles that convert heat to work. A very important question remains: Is it possible to do these transformations more efficiently and thereby conserve the work potential or chemical potential in fuel? This article shows, from a fundamental thermodynamic analysis, that it is not possible to combust carbon-based materials efficiently, that is, that the process of combustion of carbon-based materials is irreversible and that a considerable amount of the chemical potential of the fuel is lost during the combustion process. However, other substances or chemistries are explored in this work, and it is shown that some of these have the potential for more reversible combustion. These options are explored, and their potential implementation is examined by considering a coal-based power plant as an example. In particular, it is shown that CO2 emissions could be significantly reduced by using different chemical pathways to do the combustion and by combining power and chemical production. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26107463

Fischer − tropsch synthesis using H2 / CO / CO2 syngas mixtures over a cobalt catalyst / Yali Yao in Industrial & engineering chemistry research, Vol. 49 N° 21 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 11061-11066 Titre : Fischer − tropsch synthesis using H2 / CO / CO2 syngas mixtures over a cobalt catalyst Type de document : texte imprimé Auteurs : Yali Yao, Auteur ; Diane Hildebrandt, Auteur ; David Glasser, Auteur Année de publication : 2011 Article en page(s) : pp. 11061-11066 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Catalyst  Synthesis  gas  Carbon  dioxide  Fischer  Tropsch  synthesis Résumé : The effect of CO2 on Fischer−Tropsch synthesis (FTS) on a cobalt based catalyst had been investigated in a fixed-bed microreactor. Two feed gases, H2:CO:CO2 = 2:1:0 and H2:CO:CO2 = 3:0:1, were mixed in various proportions thus varying the ratio of CO, CO2, and H2 stoichiometrically. The results show that CO and CO2 mixtures can be used as feed to a cobalt catalyst. Comparison of the FTS using different syngas mixtures (CO2/H2, CO2/CO/H2, and CO/H2) shows that: (1) CO2 can be hydrogenated along with CO in the FT reactor over cobalt catalyst, especially in the case of high content of CO2. (2) Hydrogenation of CO2 or CO/CO2 mixture leads to a typical Anderson−Schulz−Flory (ASF) distribution. These could support the hypothesis that CO2 hydrogenation processes might occur with the formation of CO as intermediate. (3) CO feed exhibit the typical two-alpha distribution while CO2 and CO2 rich feeds only exhibit a single-alpha distribution. This may also help us to understand the mechanisms that lead to product distributions in FT with single- and dual-alpha distributions. In spite of the fact that cobalt catalysts are not water−gas shift active, it is shown the rate of hydrocarbon production is maximized at an intermediate composition of the CO/CO2/H2 mixture. The results could have implications for the design of XTL (anything-to-liquids is a process that converts carbon and energy containing feedstock to high quality fuels and products, such as coal-to-liquids, biomass-to-liquids and gas-to-liquids) using cobalt catalysts in that it might be advantageous to keep some carbon dioxide in the syngas feed to the FTS process. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23448002 [article] Fischer − tropsch synthesis using H2 / CO / CO2 syngas mixtures over a cobalt catalyst [texte imprimé] / Yali Yao, Auteur ; Diane Hildebrandt, Auteur ; David Glasser, Auteur . - 2011 . - pp. 11061-11066. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 11061-11066 Mots-clés : Catalyst  Synthesis  gas  Carbon  dioxide  Fischer  Tropsch  synthesis Résumé : The effect of CO2 on Fischer−Tropsch synthesis (FTS) on a cobalt based catalyst had been investigated in a fixed-bed microreactor. Two feed gases, H2:CO:CO2 = 2:1:0 and H2:CO:CO2 = 3:0:1, were mixed in various proportions thus varying the ratio of CO, CO2, and H2 stoichiometrically. The results show that CO and CO2 mixtures can be used as feed to a cobalt catalyst. Comparison of the FTS using different syngas mixtures (CO2/H2, CO2/CO/H2, and CO/H2) shows that: (1) CO2 can be hydrogenated along with CO in the FT reactor over cobalt catalyst, especially in the case of high content of CO2. (2) Hydrogenation of CO2 or CO/CO2 mixture leads to a typical Anderson−Schulz−Flory (ASF) distribution. These could support the hypothesis that CO2 hydrogenation processes might occur with the formation of CO as intermediate. (3) CO feed exhibit the typical two-alpha distribution while CO2 and CO2 rich feeds only exhibit a single-alpha distribution. This may also help us to understand the mechanisms that lead to product distributions in FT with single- and dual-alpha distributions. In spite of the fact that cobalt catalysts are not water−gas shift active, it is shown the rate of hydrocarbon production is maximized at an intermediate composition of the CO/CO2/H2 mixture. The results could have implications for the design of XTL (anything-to-liquids is a process that converts carbon and energy containing feedstock to high quality fuels and products, such as coal-to-liquids, biomass-to-liquids and gas-to-liquids) using cobalt catalysts in that it might be advantageous to keep some carbon dioxide in the syngas feed to the FTS process. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23448002

Fischer – tropsch synthesis using H2 / CO / CO2 syngas mixtures over an iron catalyst / Yali Yao in Industrial & engineering chemistry research, Vol. 50 N° 19 (Octobre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 19 (Octobre 2011) . - pp. 11002-11012 Titre : Fischer – tropsch synthesis using H2 / CO / CO2 syngas mixtures over an iron catalyst Type de document : texte imprimé Auteurs : Yali Yao, Auteur ; Xinying Liu, Auteur ; Diane Hildebrandt, Auteur Année de publication : 2011 Article en page(s) : pp. 11002-11012 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Catalyst  Synthesis  gas  Carbon  dioxide  Fischer  Tropsch  synthesis Résumé : A series of low-temperature Fischer―Tropsch synthesis (FTS) experiments using a wide range of H2/CO/CO2 syngas mixtures have been performed to provide further insight into the effect of the CO2 on an iron-based catalyst during FTS. In comparison with CO hydrogenation, the reactivity for CO2 hydrogenation was lower and produced more CH4-rich short chain paraffins. Based on the correlation between the experimental results and the thermodynamic equilibrium calculations for the water gas shift (WGS) reaction, although the WGS reaction is far from the thermodynamic equilibrium under low-temperature FTS conditions, its equilibrium constraints determine the pathways and in particular whether CO is converted to CO2 or CO2 to CO. It is possible for CO2 to convert to hydrocarbons only when the composition of co-fed CO2 has a value higher than that set by the equilibrium constraints. A remarkable feature of our experimental results was that when the FTS system was not consuming but forming CO2, the reaction rates of both the FT and the WGS reactions were independent of the partial pressures of CO and CO2. Furthermore, with a decrease in the ratio of CO2/(CO+CO2) in the feed gas, it was observed that the hydrocarbon product formation rate reached a maximum and then maintained this value, even at a very high concentration of CO2 in the H2/CO/CO2 feed mixture. These results could justify the inclusion of CO2 in the syngas feed to the iron-based catalyst FTS processes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24573296 [article] Fischer – tropsch synthesis using H2 / CO / CO2 syngas mixtures over an iron catalyst [texte imprimé] / Yali Yao, Auteur ; Xinying Liu, Auteur ; Diane Hildebrandt, Auteur . - 2011 . - pp. 11002-11012. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 19 (Octobre 2011) . - pp. 11002-11012 Mots-clés : Catalyst  Synthesis  gas  Carbon  dioxide  Fischer  Tropsch  synthesis Résumé : A series of low-temperature Fischer―Tropsch synthesis (FTS) experiments using a wide range of H2/CO/CO2 syngas mixtures have been performed to provide further insight into the effect of the CO2 on an iron-based catalyst during FTS. In comparison with CO hydrogenation, the reactivity for CO2 hydrogenation was lower and produced more CH4-rich short chain paraffins. Based on the correlation between the experimental results and the thermodynamic equilibrium calculations for the water gas shift (WGS) reaction, although the WGS reaction is far from the thermodynamic equilibrium under low-temperature FTS conditions, its equilibrium constraints determine the pathways and in particular whether CO is converted to CO2 or CO2 to CO. It is possible for CO2 to convert to hydrocarbons only when the composition of co-fed CO2 has a value higher than that set by the equilibrium constraints. A remarkable feature of our experimental results was that when the FTS system was not consuming but forming CO2, the reaction rates of both the FT and the WGS reactions were independent of the partial pressures of CO and CO2. Furthermore, with a decrease in the ratio of CO2/(CO+CO2) in the feed gas, it was observed that the hydrocarbon product formation rate reached a maximum and then maintained this value, even at a very high concentration of CO2 in the H2/CO/CO2 feed mixture. These results could justify the inclusion of CO2 in the syngas feed to the iron-based catalyst FTS processes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24573296

A Graphical method of improving the production rate from batch reactors / David Ming in Industrial & engineering chemistry research, Vol. 51 N° 42 (Octobre 2012) 

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Making sense of the fischer − tropsch synthesis reaction / Xiaojun Lu in Industrial & engineering chemistry research, Vol. 49 N° 20 (Octobre 2010) 

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A new way to look at fischer−tropsch synthesis using flushing axperiments / Xiaojun Lu in Industrial & engineering chemistry research, Vol. 50 N° 8 (Avril 2011) 

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On column profile maps / Daniel A. Beneke in Industrial & engineering chemistry research, Vol. 50 N° 10 (Mai 2011) 

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A Revised method of attainable region construction utilizing rotated bounding hyperplanes / David Ming in Industrial & engineering chemistry research, Vol. 49 N° 21 (Novembre 2010) 

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A Thermodynamic approach to olefin product distribution in fischer–tropsch synthesis / Xiaojun Lu in Industrial & engineering chemistry research, Vol. 51 N° 51 (Décembre 2012) 

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Work to chemical processes / Baraka Celestin Sempuga in Industrial & engineering chemistry research, Vol. 50 N° 14 (Juillet 2011) 

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