The production of sugars from lignocellulosic biomass is the key to a sustainable, renewable chem... more The production of sugars from lignocellulosic biomass is the key to a sustainable, renewable chemical industry. Glucose, xylose and other monosaccharides can be easily produced by hydrolyzing cellulose and hemicellulose, the primary polysaccharides in biomass. However, the hydrolysis of biomass generates byproducts that, together with the mineral acid normally added in the hydrolysis step, have to be removed before the downstream conversion processes. In this work, the recovery of monosaccharides from lignocellulosic hydrolysates by means of Ion Exclusion Chromatography (IEC) has been studied. The analyzed process relies on new pretreatment and hydrolysis steps, involving the neutralization of the hydrolysate with sodium hydroxide. The adsorption behavior of the main components involved in the separation has been experimentally investigated. Pulse tests at the high loading encountered in preparative conditions have been performed for a selected group of model components found in the...
ABSTRACT Production of synthetic liquid fuels via Fischer-Tropsch (FT)-based technologies is a va... more ABSTRACT Production of synthetic liquid fuels via Fischer-Tropsch (FT)-based technologies is a valuable way to obtain clean fuels from several raw materials. The hydrocracking process to which the waxes must be subjected has the aim to increase the yield in middle distillates and to improve the fuel cold flow properties. In this paper a mechanistically informed pathways-level kinetic model for the hydrocracking process is proposed. The model, generated by means of the INGen software, is a molecular pathway-type model that can be considered a good compromise between a detailed enough description of the system and a certain degree of simplicity that allows the application of this kind of model to complex feedstocks such as those typical of FT wax hydrocracking. In this case it may be necessary to further reduce the model equations and thus a proposal of a relumping strategy for the obtained reaction network is also shown.
Industrial Engineering Chemistry Research, Jun 29, 2007
ABSTRACT A correlation between lumped isomerization equilibrium constants (Keq) and the number of... more ABSTRACT A correlation between lumped isomerization equilibrium constants (Keq) and the number of carbon atoms in paraffinic chains has been developed. The aim of the work is to check the meaningfulness from a chemico-physical point of view of previously estimated values of Keq in order to improve the performances of a simulation model for the isomerization/hydrocracking of Fischer−Tropsch (F−T) waxes, a mixture made up of normal paraffins covering a wide range of molecular weights. Owing to the lack of experimental data for paraffins with more than ten carbon atoms, a procedure has been developed to determine equilibrium constants extrapolating the thermodynamical data of low carbon number paraffins. Since in our case the hydrocracking simulation model considers lumped classes of isomers (i.e., monobranched and multibranched), the equilibrium data do not take into account single isomerization reactions but those from a n-paraffin to the lump of its monobranched isomers and from the lump of monobranched isomers to the lump of multibranched ones. The coherence of the estimated constants has been verified by comparison with the little data available in the literature on lumped equilibrium constants. The analysis of equilibrium constants at different temperatures has shown that isomerization becomes endothermic from a number of carbon atoms equal to about 13−14 onward; this result is also supported by enthalpy data.
ABSTRACT A pathway-level kinetic model for the hydrocracking process of the Fischer-Tropsch waxes... more ABSTRACT A pathway-level kinetic model for the hydrocracking process of the Fischer-Tropsch waxes is presented. In particular, some thermodynamic and kinetic aspects are discussed. Form a thermodynamic point of view, critical properties of heavy paraffins have been computed in order to introduce the VLE calculation in the kinetic model. Moreover a new function for the equilibrium constants for isomerization reactions has been developed. For which concerns kinetics, a breakage probability function for the C-C bonds has been used instead of the assumption of the breakage in the middle of the chain. It is shown how, by correctly accounting for both thermodynamic and kinetic effects, reliable results can be obtained in modeling the hydrocracking of a complex feedstock (n-C5–C70 mixture).
... 1 , Simone Gamba 1 , Vincenzo Calemma 2 , and Susi Bonomi 2 . (1) Dipartimento di Chimica, Ma... more ... 1 , Simone Gamba 1 , Vincenzo Calemma 2 , and Susi Bonomi 2 . (1) Dipartimento di Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano, Piazza Leonardo da Vinci, 32, Milano, Italy, (2) Divisione Refining & Marketing - Centro Ricerche di San Donato Milanese, Eni ...
► The similarities between our approach and that by Péneloux are limited to the application of th... more ► The similarities between our approach and that by Péneloux are limited to the application of the classical quadratic mixing rules. ► We used the mixing rules developed by Huron and Vidal and Wilson's theory of group solutions. ► Our approach and that by Jaubert and Privat diverge in applying the group contribution method.
1997 1st International Conference, Control of Oscillations and Chaos Proceedings (Cat. No.97TH8329), 1997
... bifureat ion theory Cristina Tablino-Possio Dept. of Material Science University of Milan via... more ... bifureat ion theory Cristina Tablino-Possio Dept. of Material Science University of Milan via Emanueli, 15, 20126 Milano, Italy TablinoQvmimat .mat .unimi.it Abstract ... 967-985, 1974. [9] LBKoppel, “Input multiplicity in nonlinear, multivariable control systems,” A. I. Ch. EJ vol. ...
The Fischer-Tropsch process allows to obtain heavy hydrocarbons from synthesis gas. However, owin... more The Fischer-Tropsch process allows to obtain heavy hydrocarbons from synthesis gas. However, owing to the intrinsic characteristics of the process and the nature of the products, the FT wax need to be subjected to a catalytic hydroconversion stage in order to improve both yields and quality of middle distillate cuts. It was found that the performance of this process and the quality of products are strongly affected by the vapor-liquid equilibrium inside the catalytic reactor, so that it becomes very important to be able to accurately model this equilibrium. To do this, the Soave-Readlich-Kwong equation of state was chosen, for which reliable characterization procedures are available to describe the heavy normal paraffin behavior. In order to fully attain the objective, two more steps were necessary: (i) a way to estimate the binary interaction parameters between hydrogen and paraffins and (ii) a characterization procedure of iso-paraffins. For the first item, a literature relationsh...
Various coals, including the complete set of Argonne Premium Coal Samples, have been characterize... more Various coals, including the complete set of Argonne Premium Coal Samples, have been characterized using pyrolysis—gas chromatography/mass spectrometry (Py-GC/MS). The addition of the GC step to Py-MS was found to significantly improve the separation, identification and quantitation of volatile pyrolysis products. The analytical results were found to be independent of the storage condition of the sample, since the Py-GC/MS results obtained from three samples (two coals from Poland and Colombia and a lignite from North Dakota, USA), that were not stored under controlled conditions, fit very well all the other data.A good correlation is shown between Py-GC/MS data and both carbon content and degree of aromaticity, which in turn represent the coal rank.Although high molecular weight and highly polar fragments are undetectable in these experimental conditions, the pyrogram consitutes a fingerprint for a given coal, containing information about its macromolecular structure.
This work relates to a comparison between process solutions for the production of H2 and the copr... more This work relates to a comparison between process solutions for the production of H2 and the coproduction of H2 and energy by means of a zero emission biomass integrated gasification and a combined cycle (BIGCC) power plant. The energy production is 10 MWe, in agreement with the Small Renewable Energy Power Plant (SREP) Program, promoted by the Government of Malaysia. H2 is obtained by supercritical water gasification (SCWG), a technology of interest for the processing of biomass with high moisture content. An economic analysis has been carried out in order to demonstrate the feasibility of the process solutions and to compare their convenience. The feedstock is 280,000 t/y of Empty Fruit Bunch (EFB), a biomass obtained in the Palm Oil Industry. The location of the site is Teluk Intak District in the State of Perak (Malaysia). The processes are designed with Aspen Plus® V7.2. The aim of this work is to develop detailed process flow diagrams for the supercritical water gasification t...
Biomethane is a renewable energy source that can be used, e.g., for transportation or injection i... more Biomethane is a renewable energy source that can be used, e.g., for transportation or injection in the natural gas grids. It is obtained from proper biogas treatment. Biogas is a mixture of mainly methane and CO2 that can be produced from livestock effluents, municipal and industrial sewage sludge, energy crops, agro-industrial wastes, MSW landfills (in this case the gas is commonly called “landfill gas”) etc. In order to obtain biomethane, CO2 and other compounds must be removed from biogas. The type and the amount of pollutants depend upon the biogas source and determine which cleaning and upgrading techniques are the most suitable for gas purification. “Cleaning” is referred to as the pretreatment that allows the removal of all pollutants but carbon dioxide, while “upgrading” is the treatment for CO2 removal. Since there are no clear guidelines for choosing among different upgrading techniques, this work analyzes two of the most commonly used processes: the water scrubbing and th...
In this paper correlations that allow to compute the critical constants for heavy linear and bran... more In this paper correlations that allow to compute the critical constants for heavy linear and branched hydrocarbons are presented. The critical temperatures of alkanes are correlated to their normal boiling points and the critical pressures and the acentric factors are adjusted to reproduce the boiling point at 10 mmHg and 760 mmHg by the Soave-Redlich-Kwong equation of state (SRK-EoS). The above-mentioned method, originally proposed for C7÷C40 hydrocarbons, is here extended to C100 and also branched paraffins’ properties are esteemed only knowing their normal boiling points.
CO2 capture from exhaust gas of power plants, natural gas and refinery gas can be successfully ac... more CO2 capture from exhaust gas of power plants, natural gas and refinery gas can be successfully achieved by chemical absorption with alkanolamines. CO2 capture from exhaust gas is often obtained by absorption with monoethanolamine (MEA) which is the most frequently used solvent for this purpose. Thermodynamics, kinetics and mass transfer influence the chemical absorption process. Acidic gases and amines are weak electrolytes, which partially dissociate in the aqueous phase: the high non-ideality of the liquid phase must be properly taken into account, by employing a γ/φ method. Kinetics and mass transfer can be described using two different approaches: the “equilibrium-based stage efficiency” model or the “rate-based” one. ASPEN Plus® uses the rate-based model, but the prediction of mass transfer coefficients is based on the film theory by Lewis and Whitman, while other theories can more conveniently be used, i.e. the Eddy Diffusivity theory. Since ASPEN Plus® simulator is suitable t...
This work relates to a zero emission biomass integrated gasification and combined cycle (BIGCC) p... more This work relates to a zero emission biomass integrated gasification and combined cycle (BIGCC) power plant, designed to produce 10 [MWe], in agreement with the Small Renewable Energy Power Plant (SREP) Program, promoted by the Government of Malaysia, and 11.67 [kt/y] of pure hydrogen. Hydrogen is obtained by supercritical water gasification (SCWG), a technology of interest for processing biomass with high moisture content. An economic analysis has been carried out in order to demonstrate the feasibility of the process. The plant is fed with 280000 [t/y] of Empty Fruit Bunch (EFB), a biomass obtained in the Palm Oil Industry. The location of the site is Teluk Intak District in the State of Perak (Malaysia). The process is designed with Aspen Plus® V7.2. The designed plant is able to supply hydrogen and power with zero emissions and all wastes are used as value added products.
A thermodynamic model, suitable for an accurate description of phase equilibrium of strongly non-... more A thermodynamic model, suitable for an accurate description of phase equilibrium of strongly non-ideal mixtures, is fundamental for the simulation and, consequently, the process optimization of the extractive distillation of the azeotropic ethanol–water mixture, using ethylene glycol as entrainer. Aspen PLUS® has been used to simulate the process for the concentration and dehydration of the hydro-alcoholic solution, coming from agricultural biomass fermentation, to obtain high purity ethanol. The application of the proposed thermodynamic model (that belongs to the class of the direct methods) leads to more reliable results and thus allows the correct choice of the best alternative for energy saving in order to make the production of bioethanol industrially competitive.
The production of sugars from lignocellulosic biomass is the key to a sustainable, renewable chem... more The production of sugars from lignocellulosic biomass is the key to a sustainable, renewable chemical industry. Glucose, xylose and other monosaccharides can be easily produced by hydrolyzing cellulose and hemicellulose, the primary polysaccharides in biomass. However, the hydrolysis of biomass generates byproducts that, together with the mineral acid normally added in the hydrolysis step, have to be removed before the downstream conversion processes. In this work, the recovery of monosaccharides from lignocellulosic hydrolysates by means of Ion Exclusion Chromatography (IEC) has been studied. The analyzed process relies on new pretreatment and hydrolysis steps, involving the neutralization of the hydrolysate with sodium hydroxide. The adsorption behavior of the main components involved in the separation has been experimentally investigated. Pulse tests at the high loading encountered in preparative conditions have been performed for a selected group of model components found in the...
ABSTRACT Production of synthetic liquid fuels via Fischer-Tropsch (FT)-based technologies is a va... more ABSTRACT Production of synthetic liquid fuels via Fischer-Tropsch (FT)-based technologies is a valuable way to obtain clean fuels from several raw materials. The hydrocracking process to which the waxes must be subjected has the aim to increase the yield in middle distillates and to improve the fuel cold flow properties. In this paper a mechanistically informed pathways-level kinetic model for the hydrocracking process is proposed. The model, generated by means of the INGen software, is a molecular pathway-type model that can be considered a good compromise between a detailed enough description of the system and a certain degree of simplicity that allows the application of this kind of model to complex feedstocks such as those typical of FT wax hydrocracking. In this case it may be necessary to further reduce the model equations and thus a proposal of a relumping strategy for the obtained reaction network is also shown.
Industrial Engineering Chemistry Research, Jun 29, 2007
ABSTRACT A correlation between lumped isomerization equilibrium constants (Keq) and the number of... more ABSTRACT A correlation between lumped isomerization equilibrium constants (Keq) and the number of carbon atoms in paraffinic chains has been developed. The aim of the work is to check the meaningfulness from a chemico-physical point of view of previously estimated values of Keq in order to improve the performances of a simulation model for the isomerization/hydrocracking of Fischer−Tropsch (F−T) waxes, a mixture made up of normal paraffins covering a wide range of molecular weights. Owing to the lack of experimental data for paraffins with more than ten carbon atoms, a procedure has been developed to determine equilibrium constants extrapolating the thermodynamical data of low carbon number paraffins. Since in our case the hydrocracking simulation model considers lumped classes of isomers (i.e., monobranched and multibranched), the equilibrium data do not take into account single isomerization reactions but those from a n-paraffin to the lump of its monobranched isomers and from the lump of monobranched isomers to the lump of multibranched ones. The coherence of the estimated constants has been verified by comparison with the little data available in the literature on lumped equilibrium constants. The analysis of equilibrium constants at different temperatures has shown that isomerization becomes endothermic from a number of carbon atoms equal to about 13−14 onward; this result is also supported by enthalpy data.
ABSTRACT A pathway-level kinetic model for the hydrocracking process of the Fischer-Tropsch waxes... more ABSTRACT A pathway-level kinetic model for the hydrocracking process of the Fischer-Tropsch waxes is presented. In particular, some thermodynamic and kinetic aspects are discussed. Form a thermodynamic point of view, critical properties of heavy paraffins have been computed in order to introduce the VLE calculation in the kinetic model. Moreover a new function for the equilibrium constants for isomerization reactions has been developed. For which concerns kinetics, a breakage probability function for the C-C bonds has been used instead of the assumption of the breakage in the middle of the chain. It is shown how, by correctly accounting for both thermodynamic and kinetic effects, reliable results can be obtained in modeling the hydrocracking of a complex feedstock (n-C5–C70 mixture).
... 1 , Simone Gamba 1 , Vincenzo Calemma 2 , and Susi Bonomi 2 . (1) Dipartimento di Chimica, Ma... more ... 1 , Simone Gamba 1 , Vincenzo Calemma 2 , and Susi Bonomi 2 . (1) Dipartimento di Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano, Piazza Leonardo da Vinci, 32, Milano, Italy, (2) Divisione Refining & Marketing - Centro Ricerche di San Donato Milanese, Eni ...
► The similarities between our approach and that by Péneloux are limited to the application of th... more ► The similarities between our approach and that by Péneloux are limited to the application of the classical quadratic mixing rules. ► We used the mixing rules developed by Huron and Vidal and Wilson's theory of group solutions. ► Our approach and that by Jaubert and Privat diverge in applying the group contribution method.
1997 1st International Conference, Control of Oscillations and Chaos Proceedings (Cat. No.97TH8329), 1997
... bifureat ion theory Cristina Tablino-Possio Dept. of Material Science University of Milan via... more ... bifureat ion theory Cristina Tablino-Possio Dept. of Material Science University of Milan via Emanueli, 15, 20126 Milano, Italy TablinoQvmimat .mat .unimi.it Abstract ... 967-985, 1974. [9] LBKoppel, “Input multiplicity in nonlinear, multivariable control systems,” A. I. Ch. EJ vol. ...
The Fischer-Tropsch process allows to obtain heavy hydrocarbons from synthesis gas. However, owin... more The Fischer-Tropsch process allows to obtain heavy hydrocarbons from synthesis gas. However, owing to the intrinsic characteristics of the process and the nature of the products, the FT wax need to be subjected to a catalytic hydroconversion stage in order to improve both yields and quality of middle distillate cuts. It was found that the performance of this process and the quality of products are strongly affected by the vapor-liquid equilibrium inside the catalytic reactor, so that it becomes very important to be able to accurately model this equilibrium. To do this, the Soave-Readlich-Kwong equation of state was chosen, for which reliable characterization procedures are available to describe the heavy normal paraffin behavior. In order to fully attain the objective, two more steps were necessary: (i) a way to estimate the binary interaction parameters between hydrogen and paraffins and (ii) a characterization procedure of iso-paraffins. For the first item, a literature relationsh...
Various coals, including the complete set of Argonne Premium Coal Samples, have been characterize... more Various coals, including the complete set of Argonne Premium Coal Samples, have been characterized using pyrolysis—gas chromatography/mass spectrometry (Py-GC/MS). The addition of the GC step to Py-MS was found to significantly improve the separation, identification and quantitation of volatile pyrolysis products. The analytical results were found to be independent of the storage condition of the sample, since the Py-GC/MS results obtained from three samples (two coals from Poland and Colombia and a lignite from North Dakota, USA), that were not stored under controlled conditions, fit very well all the other data.A good correlation is shown between Py-GC/MS data and both carbon content and degree of aromaticity, which in turn represent the coal rank.Although high molecular weight and highly polar fragments are undetectable in these experimental conditions, the pyrogram consitutes a fingerprint for a given coal, containing information about its macromolecular structure.
This work relates to a comparison between process solutions for the production of H2 and the copr... more This work relates to a comparison between process solutions for the production of H2 and the coproduction of H2 and energy by means of a zero emission biomass integrated gasification and a combined cycle (BIGCC) power plant. The energy production is 10 MWe, in agreement with the Small Renewable Energy Power Plant (SREP) Program, promoted by the Government of Malaysia. H2 is obtained by supercritical water gasification (SCWG), a technology of interest for the processing of biomass with high moisture content. An economic analysis has been carried out in order to demonstrate the feasibility of the process solutions and to compare their convenience. The feedstock is 280,000 t/y of Empty Fruit Bunch (EFB), a biomass obtained in the Palm Oil Industry. The location of the site is Teluk Intak District in the State of Perak (Malaysia). The processes are designed with Aspen Plus® V7.2. The aim of this work is to develop detailed process flow diagrams for the supercritical water gasification t...
Biomethane is a renewable energy source that can be used, e.g., for transportation or injection i... more Biomethane is a renewable energy source that can be used, e.g., for transportation or injection in the natural gas grids. It is obtained from proper biogas treatment. Biogas is a mixture of mainly methane and CO2 that can be produced from livestock effluents, municipal and industrial sewage sludge, energy crops, agro-industrial wastes, MSW landfills (in this case the gas is commonly called “landfill gas”) etc. In order to obtain biomethane, CO2 and other compounds must be removed from biogas. The type and the amount of pollutants depend upon the biogas source and determine which cleaning and upgrading techniques are the most suitable for gas purification. “Cleaning” is referred to as the pretreatment that allows the removal of all pollutants but carbon dioxide, while “upgrading” is the treatment for CO2 removal. Since there are no clear guidelines for choosing among different upgrading techniques, this work analyzes two of the most commonly used processes: the water scrubbing and th...
In this paper correlations that allow to compute the critical constants for heavy linear and bran... more In this paper correlations that allow to compute the critical constants for heavy linear and branched hydrocarbons are presented. The critical temperatures of alkanes are correlated to their normal boiling points and the critical pressures and the acentric factors are adjusted to reproduce the boiling point at 10 mmHg and 760 mmHg by the Soave-Redlich-Kwong equation of state (SRK-EoS). The above-mentioned method, originally proposed for C7÷C40 hydrocarbons, is here extended to C100 and also branched paraffins’ properties are esteemed only knowing their normal boiling points.
CO2 capture from exhaust gas of power plants, natural gas and refinery gas can be successfully ac... more CO2 capture from exhaust gas of power plants, natural gas and refinery gas can be successfully achieved by chemical absorption with alkanolamines. CO2 capture from exhaust gas is often obtained by absorption with monoethanolamine (MEA) which is the most frequently used solvent for this purpose. Thermodynamics, kinetics and mass transfer influence the chemical absorption process. Acidic gases and amines are weak electrolytes, which partially dissociate in the aqueous phase: the high non-ideality of the liquid phase must be properly taken into account, by employing a γ/φ method. Kinetics and mass transfer can be described using two different approaches: the “equilibrium-based stage efficiency” model or the “rate-based” one. ASPEN Plus® uses the rate-based model, but the prediction of mass transfer coefficients is based on the film theory by Lewis and Whitman, while other theories can more conveniently be used, i.e. the Eddy Diffusivity theory. Since ASPEN Plus® simulator is suitable t...
This work relates to a zero emission biomass integrated gasification and combined cycle (BIGCC) p... more This work relates to a zero emission biomass integrated gasification and combined cycle (BIGCC) power plant, designed to produce 10 [MWe], in agreement with the Small Renewable Energy Power Plant (SREP) Program, promoted by the Government of Malaysia, and 11.67 [kt/y] of pure hydrogen. Hydrogen is obtained by supercritical water gasification (SCWG), a technology of interest for processing biomass with high moisture content. An economic analysis has been carried out in order to demonstrate the feasibility of the process. The plant is fed with 280000 [t/y] of Empty Fruit Bunch (EFB), a biomass obtained in the Palm Oil Industry. The location of the site is Teluk Intak District in the State of Perak (Malaysia). The process is designed with Aspen Plus® V7.2. The designed plant is able to supply hydrogen and power with zero emissions and all wastes are used as value added products.
A thermodynamic model, suitable for an accurate description of phase equilibrium of strongly non-... more A thermodynamic model, suitable for an accurate description of phase equilibrium of strongly non-ideal mixtures, is fundamental for the simulation and, consequently, the process optimization of the extractive distillation of the azeotropic ethanol–water mixture, using ethylene glycol as entrainer. Aspen PLUS® has been used to simulate the process for the concentration and dehydration of the hydro-alcoholic solution, coming from agricultural biomass fermentation, to obtain high purity ethanol. The application of the proposed thermodynamic model (that belongs to the class of the direct methods) leads to more reliable results and thus allows the correct choice of the best alternative for energy saving in order to make the production of bioethanol industrially competitive.
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