Documents disponibles écrits par cet auteur

Coupling exothermic and endothermic reactions in plug-flow reactor-separation-recycle systems / Pietro Altimari in Industrial & engineering chemistry research, Vol. 47 N°17 (Septembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6685–6697 Titre : Coupling exothermic and endothermic reactions in plug-flow reactor-separation-recycle systems Type de document : texte imprimé Auteurs : Pietro Altimari, Auteur ; Costin Sorin Bildea, Auteur Année de publication : 2008 Article en page(s) : p. 6685–6697 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Plug-flow  reactor-separation-recycle  systems  Exothermic  reaction  Endothermic  reaction Résumé : The nonlinear behavior of plug-flow reactor−separation−recycle systems, where the endothermic first-order reaction A → R + Q and the exothermic second-order reaction B + Q → P simultaneously take place, is investigated. As the physical properties of the species involved vary, possible flowsheets are identified and feasible control strategies are suggested. Bifurcation analysis of the reactor−separation−recycle system is performed by choosing set-point variables as bifurcation parameters. Steady state multiplicity is invariably detected leading to complex behavior. Implications on plantwide control are thoroughly discussed and guidelines are provided which enable to select values of set-point variables in a way that guarantees safe operation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071367g [article] Coupling exothermic and endothermic reactions in plug-flow reactor-separation-recycle systems [texte imprimé] / Pietro Altimari, Auteur ; Costin Sorin Bildea, Auteur . - 2008 . - p. 6685–6697. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°17 (Septembre 2008) . - p. 6685–6697 Mots-clés : Plug-flow  reactor-separation-recycle  systems  Exothermic  reaction  Endothermic  reaction Résumé : The nonlinear behavior of plug-flow reactor−separation−recycle systems, where the endothermic first-order reaction A → R + Q and the exothermic second-order reaction B + Q → P simultaneously take place, is investigated. As the physical properties of the species involved vary, possible flowsheets are identified and feasible control strategies are suggested. Bifurcation analysis of the reactor−separation−recycle system is performed by choosing set-point variables as bifurcation parameters. Steady state multiplicity is invariably detected leading to complex behavior. Implications on plantwide control are thoroughly discussed and guidelines are provided which enable to select values of set-point variables in a way that guarantees safe operation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071367g

Formation of thermal wave trains in loop reactors / Pietro Altimari in Industrial & engineering chemistry research, Vol. 51 N° 28 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 28 (Juillet 2012) . - pp. 9609-9619 Titre : Formation of thermal wave trains in loop reactors : Stability limits and spatiotemporal structure for reversible reactions Type de document : texte imprimé Auteurs : Pietro Altimari, Auteur ; Erasmo Mancusi, Auteur ; Silvestro Crescitelli, Auteur Année de publication : 2012 Article en page(s) : pp. 9609-9619 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Reversible  reaction  Stability  Reactor  Thermal  wave Résumé : Networks of fixed bed reactors with periodically switched inlet and outlet sections are studied with reference to equilibrium limited reactions. The methanol synthesis is selected as representative reaction example and the mechanisms governing the emergence of periodic regimes corresponding to trains of traveling thermal waves are analyzed. Analytical approximations, accounting for the influence of the implemented switching strategy and in satisfactory agreement with numerical simulation, are derived for the switch time stability limits in terms of temperature fronts velocities. Large and sudden variations in the switch time stability range of any wave train solution are demonstrated to occur when the sum of the velocities of declining temperature fronts exceeds the sum of the velocities of rising temperature fronts. The illustrated results provide indications on how to design and operate the network so as to generate thermal wave trains with desired number of waves and stability limits. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26163298 [article] Formation of thermal wave trains in loop reactors : Stability limits and spatiotemporal structure for reversible reactions [texte imprimé] / Pietro Altimari, Auteur ; Erasmo Mancusi, Auteur ; Silvestro Crescitelli, Auteur . - 2012 . - pp. 9609-9619. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 28 (Juillet 2012) . - pp. 9609-9619 Mots-clés : Reversible  reaction  Stability  Reactor  Thermal  wave Résumé : Networks of fixed bed reactors with periodically switched inlet and outlet sections are studied with reference to equilibrium limited reactions. The methanol synthesis is selected as representative reaction example and the mechanisms governing the emergence of periodic regimes corresponding to trains of traveling thermal waves are analyzed. Analytical approximations, accounting for the influence of the implemented switching strategy and in satisfactory agreement with numerical simulation, are derived for the switch time stability limits in terms of temperature fronts velocities. Large and sudden variations in the switch time stability range of any wave train solution are demonstrated to occur when the sum of the velocities of declining temperature fronts exceeds the sum of the velocities of rising temperature fronts. The illustrated results provide indications on how to design and operate the network so as to generate thermal wave trains with desired number of waves and stability limits. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26163298

Optimal Reference Trajectory Shaping and Robust Gain-Scheduling for Transition Control of Nonlinear Processes / Pietro Altimari in Industrial & engineering chemistry research, Vol. 48 N° 20 (Octobre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 20 (Octobre 2009) . - pp. 9128–9140 Titre : Optimal Reference Trajectory Shaping and Robust Gain-Scheduling for Transition Control of Nonlinear Processes Type de document : texte imprimé Auteurs : Pietro Altimari, Auteur ; Lucia Russo, Auteur ; Erasmo Mancusi, Auteur Année de publication : 2010 Article en page(s) : pp. 9128–9140 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Nonlinear  processes  Transition  control  Gain  scheduling Résumé : A novel method for transition control of nonlinear processes is presented. Gain scheduling is implemented to ensure stability and desired output behavior over the operating region of interest while transition between the initial and the final steady state is achieved by predictive reference control (or reference governor). In this framework, the search of a feasible reference input sequence is performed so that the closed-loop system moves along an optimal curve of steady states. This curve is constructed off-line so that its points lie far from the border of the process constraint set and correspond to satisfactory controllability properties of the uncontrolled plant. Moreover, bifurcation analysis of the closed-loop system is performed by varying the reference signal according to the selected curve. In this way, regions of state multiplicity and/or instability are identified enabling the choice of the controller parameters values preventing transitions to undesired solution regimes. The method is validated on a simulated problem of start-up control of a jacketed continuous stirred tank reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9001553 [article] Optimal Reference Trajectory Shaping and Robust Gain-Scheduling for Transition Control of Nonlinear Processes [texte imprimé] / Pietro Altimari, Auteur ; Lucia Russo, Auteur ; Erasmo Mancusi, Auteur . - 2010 . - pp. 9128–9140. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 20 (Octobre 2009) . - pp. 9128–9140 Mots-clés : Nonlinear  processes  Transition  control  Gain  scheduling Résumé : A novel method for transition control of nonlinear processes is presented. Gain scheduling is implemented to ensure stability and desired output behavior over the operating region of interest while transition between the initial and the final steady state is achieved by predictive reference control (or reference governor). In this framework, the search of a feasible reference input sequence is performed so that the closed-loop system moves along an optimal curve of steady states. This curve is constructed off-line so that its points lie far from the border of the process constraint set and correspond to satisfactory controllability properties of the uncontrolled plant. Moreover, bifurcation analysis of the closed-loop system is performed by varying the reference signal according to the selected curve. In this way, regions of state multiplicity and/or instability are identified enabling the choice of the controller parameters values preventing transitions to undesired solution regimes. The method is validated on a simulated problem of start-up control of a jacketed continuous stirred tank reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9001553