Documents disponibles écrits par cet auteur

Efficient optimization-based design of distillation processes for homogeneous azeotropic mixtures / Korbinian Kraemer in Industrial & engineering chemistry research, Vol. 48 N° 14 (Juillet 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6749–6764 Titre : Efficient optimization-based design of distillation processes for homogeneous azeotropic mixtures Type de document : texte imprimé Auteurs : Korbinian Kraemer, Auteur ; Sven Kossack, Auteur ; Marquardt, Wolfgang, Auteur Année de publication : 2009 Article en page(s) : pp. 6749–6764 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Complex  distillation  processes  Azeotropic  multicomponent  mixture  Outstanding  robustness Résumé : Rigorous optimization is a valuable tool that can support the engineer to tap the full economic potential of a distillation process. Unfortunately, the solution of these large-scale discrete-continuous optimization problems usually suffers from a lack of robustness, long computational times, and a low reliability toward good local optima. In this paper, the rigorous optimization of complex distillation processes for azeotropic multicomponent mixtures is achieved with outstanding robustness, reliability, and efficiency through progress on two levels. First, the integration within a process synthesis framework allows a reduction of the complexity of the optimization superstructure and provides an excellent initialization by shortcut evaluation with the rectification body method. Second, the reformulation as a purely continuous optimization problem enables a solution with reliable and efficient NLP solvers. Moreover, the continuous reformulation considers a particular tight column model formulation such that the introduction of special nonlinear constraints to force integer decisions could be largely avoided. A careful initialization phase and a stepwise solution procedure with gradually tightened bounds facilitate a robust and efficient solution. Different superstructures for the tray optimization of distillation columns are tested. The methods are illustrated by three demanding case studies. The first case study considers the conceptual design as well as the rigorous optimization of a curved boundary process for the complete separation of an azeotropic four-component mixture. The rigorous optimization of a pressure swing process for the separation of a highly nonideal five component mixture is presented in the second case study. Finally, the third case study covers the rigorous optimization of an extractive separation within a complex column system. All case studies could be robustly solved due to the favorable initialization phase. The continuously reformulated problems required significantly less computational time and identified local optima of better quality as compared to the mixed-integer nonlinear programming techniques (MINLP) solution. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900143e [article] Efficient optimization-based design of distillation processes for homogeneous azeotropic mixtures [texte imprimé] / Korbinian Kraemer, Auteur ; Sven Kossack, Auteur ; Marquardt, Wolfgang, Auteur . - 2009 . - pp. 6749–6764. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6749–6764 Mots-clés : Complex  distillation  processes  Azeotropic  multicomponent  mixture  Outstanding  robustness Résumé : Rigorous optimization is a valuable tool that can support the engineer to tap the full economic potential of a distillation process. Unfortunately, the solution of these large-scale discrete-continuous optimization problems usually suffers from a lack of robustness, long computational times, and a low reliability toward good local optima. In this paper, the rigorous optimization of complex distillation processes for azeotropic multicomponent mixtures is achieved with outstanding robustness, reliability, and efficiency through progress on two levels. First, the integration within a process synthesis framework allows a reduction of the complexity of the optimization superstructure and provides an excellent initialization by shortcut evaluation with the rectification body method. Second, the reformulation as a purely continuous optimization problem enables a solution with reliable and efficient NLP solvers. Moreover, the continuous reformulation considers a particular tight column model formulation such that the introduction of special nonlinear constraints to force integer decisions could be largely avoided. A careful initialization phase and a stepwise solution procedure with gradually tightened bounds facilitate a robust and efficient solution. Different superstructures for the tray optimization of distillation columns are tested. The methods are illustrated by three demanding case studies. The first case study considers the conceptual design as well as the rigorous optimization of a curved boundary process for the complete separation of an azeotropic four-component mixture. The rigorous optimization of a pressure swing process for the separation of a highly nonideal five component mixture is presented in the second case study. Finally, the third case study covers the rigorous optimization of an extractive separation within a complex column system. All case studies could be robustly solved due to the favorable initialization phase. The continuously reformulated problems required significantly less computational time and identified local optima of better quality as compared to the mixed-integer nonlinear programming techniques (MINLP) solution. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900143e

Incremental global parameter estimation in dynamical systems / Michalik, Claas in Industrial & engineering chemistry research, Vol. 48 N° 11 (Juin 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 11 (Juin 2009) . - pp. 5489–5497 Titre : Incremental global parameter estimation in dynamical systems Type de document : texte imprimé Auteurs : Michalik, Claas, Auteur ; Benoît Chachuat, Auteur ; Marquardt, Wolfgang, Auteur Année de publication : 2009 Article en page(s) : pp. 5489–5497 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Dynamical  system  Efficient  computational  method  Software  packages  Incremental  identification Résumé : Estimating the parameters of a dynamical system based on measurements is an important task in industrial and scientific practice. Since a model’s quality is directly linked to its parameter values, obtaining globally rather than locally optimal values is especially important in this context. In practice, however, local methods are used almost exclusively. This is mainly due to the high computational cost of global dynamic parameter estimation, which limits its application to relatively small problems comprising no more than a few equations and parameters. In addition, there is still a lack of software packages that allow global parameter estimation in dynamical systems without expert knowledge. Therefore, we propose an efficient computational method for obtaining globally optimal parameter estimates of dynamical systems using well-established, user-friendly software packages. The method is based on the so-called incremental identification procedure, in combination with deterministic global optimization tools for nonlinear programs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8015472 [article] Incremental global parameter estimation in dynamical systems [texte imprimé] / Michalik, Claas, Auteur ; Benoît Chachuat, Auteur ; Marquardt, Wolfgang, Auteur . - 2009 . - pp. 5489–5497. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 11 (Juin 2009) . - pp. 5489–5497 Mots-clés : Dynamical  system  Efficient  computational  method  Software  packages  Incremental  identification Résumé : Estimating the parameters of a dynamical system based on measurements is an important task in industrial and scientific practice. Since a model’s quality is directly linked to its parameter values, obtaining globally rather than locally optimal values is especially important in this context. In practice, however, local methods are used almost exclusively. This is mainly due to the high computational cost of global dynamic parameter estimation, which limits its application to relatively small problems comprising no more than a few equations and parameters. In addition, there is still a lack of software packages that allow global parameter estimation in dynamical systems without expert knowledge. Therefore, we propose an efficient computational method for obtaining globally optimal parameter estimates of dynamical systems using well-established, user-friendly software packages. The method is based on the so-called incremental identification procedure, in combination with deterministic global optimization tools for nonlinear programs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8015472

Optimal experimental design for discriminating numerous model candidates / Michalik, Claas in Industrial & engineering chemistry research, Vol. 49 N° 2 (Janvier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 2 (Janvier 2010) . - pp 913–919 Titre : Optimal experimental design for discriminating numerous model candidates : the AWDC criterion Type de document : texte imprimé Auteurs : Michalik, Claas, Auteur ; Stuckert, Maxim, Auteur ; Marquardt, Wolfgang, Auteur Année de publication : 2010 Article en page(s) : pp 913–919 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Optimal  experimental  Discriminating  numerous. Résumé : While model-based optimal experimental design (OED) strategies aiming at maximizing the parameter precision are regularly applied in industry and academia, only a little attention has been payed to OED techniques for model discrimination in practical applications. A broader use of these techniques is mainly hindered by two drawbacks: (i) The use of such techniques is desirable in an early model identification phase, where only a little knowledge on the process is available. The known methods, however, rely on good estimates of the parameters of all candidate model structures. (ii) The available methods are tailored to few (ideally two) model candidates and do not work well if numerous candidate structures are taken into account. In this work we propose a novel design criterion for model-based OED for model discrimination in the case of multiple model candidates. The resulting OED method is thus well-suited for designing experiments in an early stage of the model identification process to efficiently reduce the number of model candidates, thereby reducing the overall cost for model identification. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900903u [article] Optimal experimental design for discriminating numerous model candidates : the AWDC criterion [texte imprimé] / Michalik, Claas, Auteur ; Stuckert, Maxim, Auteur ; Marquardt, Wolfgang, Auteur . - 2010 . - pp 913–919. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 2 (Janvier 2010) . - pp 913–919 Mots-clés : Optimal  experimental  Discriminating  numerous. Résumé : While model-based optimal experimental design (OED) strategies aiming at maximizing the parameter precision are regularly applied in industry and academia, only a little attention has been payed to OED techniques for model discrimination in practical applications. A broader use of these techniques is mainly hindered by two drawbacks: (i) The use of such techniques is desirable in an early model identification phase, where only a little knowledge on the process is available. The known methods, however, rely on good estimates of the parameters of all candidate model structures. (ii) The available methods are tailored to few (ideally two) model candidates and do not work well if numerous candidate structures are taken into account. In this work we propose a novel design criterion for model-based OED for model discrimination in the case of multiple model candidates. The resulting OED method is thus well-suited for designing experiments in an early stage of the model identification process to efficiently reduce the number of model candidates, thereby reducing the overall cost for model identification. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900903u

Process analysis by means of focused beam reflectance measurements / Norbert Kail in Industrial & engineering chemistry research, Vol. 48 N° 6 (Mars 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2936–2946 Titre : Process analysis by means of focused beam reflectance measurements Type de document : texte imprimé Auteurs : Norbert Kail, Auteur ; Marquardt, Wolfgang, Auteur ; Heiko Briesen, Auteur Année de publication : 2009 Article en page(s) : pp. 2936–2946 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Process  analytical  technology  In  situ  particle  characterization  Focused  Beam  Reflectance  Measurement  Chord-length  distribution  Particle  size  distribution Résumé : Especially for the production of active pharmaceutical ingredients, the use of process analytical technology (PAT) is highly encouraged by the U.S. Food and Drug Administration. In crystallization and granulation processes, in situ particle characterization is the most important PAT. The technique of Focused Beam Reflectance Measurement (FBRM) is very well-suited for in situ particle characterization. A large community of users successfully applies FBRM technology for monitoring, fault detection, and quality control of dynamic processes. However, FBRM measurements are not easy to interpret, because the measured chord-length distribution (CLD) is different from any type of particle size distribution (PSD). For monitoring purposes, moments of the PSD are usually correlated empirically to moments of the CLD. Alternatively, process phenomena such as secondary nucleation and particle growth can be attributed to the time evolution of the number of chords detected in a length interval. To the authors’ knowledge, no publication has examined the accuracy of such correlations or presented a methodology to set the boundaries for the chord-length intervals. In this work, a mathematical method is presented with which a set of measured CLDs can be reduced to a small number of chord length classes, so that the class boundaries are chosen in an optimal way. A reconstruction of PSDs from FBRM data is not used for process monitoring in this work, because such a reconstruction may lack accuracy, as shown in earlier work [Kail et al. Chem. Eng. Sci. 2009]. The method presented in this work relies either on a simulation using the optical FBRM model presented in earlier work [Kail et al. Powder Technol. 2008, 185 (3), 211−222] or on reference experiments. With the presented methods, a batch crystallization of α-lactose monohydrate is analyzed. In addition, measurement artifacts observed in FBRM data are explained and discussed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800839s [article] Process analysis by means of focused beam reflectance measurements [texte imprimé] / Norbert Kail, Auteur ; Marquardt, Wolfgang, Auteur ; Heiko Briesen, Auteur . - 2009 . - pp. 2936–2946. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2936–2946 Mots-clés : Process  analytical  technology  In  situ  particle  characterization  Focused  Beam  Reflectance  Measurement  Chord-length  distribution  Particle  size  distribution Résumé : Especially for the production of active pharmaceutical ingredients, the use of process analytical technology (PAT) is highly encouraged by the U.S. Food and Drug Administration. In crystallization and granulation processes, in situ particle characterization is the most important PAT. The technique of Focused Beam Reflectance Measurement (FBRM) is very well-suited for in situ particle characterization. A large community of users successfully applies FBRM technology for monitoring, fault detection, and quality control of dynamic processes. However, FBRM measurements are not easy to interpret, because the measured chord-length distribution (CLD) is different from any type of particle size distribution (PSD). For monitoring purposes, moments of the PSD are usually correlated empirically to moments of the CLD. Alternatively, process phenomena such as secondary nucleation and particle growth can be attributed to the time evolution of the number of chords detected in a length interval. To the authors’ knowledge, no publication has examined the accuracy of such correlations or presented a methodology to set the boundaries for the chord-length intervals. In this work, a mathematical method is presented with which a set of measured CLDs can be reduced to a small number of chord length classes, so that the class boundaries are chosen in an optimal way. A reconstruction of PSDs from FBRM data is not used for process monitoring in this work, because such a reconstruction may lack accuracy, as shown in earlier work [Kail et al. Chem. Eng. Sci. 2009]. The method presented in this work relies either on a simulation using the optical FBRM model presented in earlier work [Kail et al. Powder Technol. 2008, 185 (3), 211−222] or on reference experiments. With the presented methods, a batch crystallization of α-lactose monohydrate is analyzed. In addition, measurement artifacts observed in FBRM data are explained and discussed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800839s