Documents disponibles écrits par cet auteur

Analysis of optimal control problems and plant debottlenecking for urea granulation circuits / Ivana M. Cotabarren in Industrial & engineering chemistry research, Vol. 50 N° 21 (Novembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 21 (Novembre 2011) . - pp. 11996-12010 Titre : Analysis of optimal control problems and plant debottlenecking for urea granulation circuits Type de document : texte imprimé Auteurs : Ivana M. Cotabarren, Auteur ; Diego Bertín, Auteur ; Juliana Pina, Auteur Année de publication : 2011 Article en page(s) : pp. 11996-12010 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Granulation  Optimal  control Résumé : The optimal control of a complete urea granulation circuit is studied in this work. The dynamic circuit operation is modeled by means of population, mass, and energy balances for the equipment of an industrial urea granulation flowsheet. The objective for the optimal control of the granulation circuit is to drive the process from a given steady-state (corresponding to the nominal capacity of a large-scale plant) to another one, by maximizing the throughput during the transient To this aim, realistic operating constraints are taken into account and, based on an analysis of the active physical limitations, different optimal control variables are selected (i.e., urea melt flow rate, granulator discharge area, and granulator fluidization air temperature and mass flow rate). The results provide new promising operating points, which can be achieved by tracking the calculated optimal time-trajectories for the selected control variables, and give insights into the main plant bottlenecks. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24697520 [article] Analysis of optimal control problems and plant debottlenecking for urea granulation circuits [texte imprimé] / Ivana M. Cotabarren, Auteur ; Diego Bertín, Auteur ; Juliana Pina, Auteur . - 2011 . - pp. 11996-12010. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 21 (Novembre 2011) . - pp. 11996-12010 Mots-clés : Granulation  Optimal  control Résumé : The optimal control of a complete urea granulation circuit is studied in this work. The dynamic circuit operation is modeled by means of population, mass, and energy balances for the equipment of an industrial urea granulation flowsheet. The objective for the optimal control of the granulation circuit is to drive the process from a given steady-state (corresponding to the nominal capacity of a large-scale plant) to another one, by maximizing the throughput during the transient To this aim, realistic operating constraints are taken into account and, based on an analysis of the active physical limitations, different optimal control variables are selected (i.e., urea melt flow rate, granulator discharge area, and granulator fluidization air temperature and mass flow rate). The results provide new promising operating points, which can be achieved by tracking the calculated optimal time-trajectories for the selected control variables, and give insights into the main plant bottlenecks. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24697520

Dynamic simulation and optimization of a urea granulation circuit / Ivana M. Cotabarren in Industrial & engineering chemistry research, Vol. 49 N° 14 (Juillet 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 14 (Juillet 2010) . - pp. 6630–6640 Titre : Dynamic simulation and optimization of a urea granulation circuit Type de document : texte imprimé Auteurs : Ivana M. Cotabarren, Auteur ; Diego Bertín, Auteur ; José Romagnoli, Auteur Année de publication : 2010 Article en page(s) : pp. 6630–6640 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Granulation  circuit Résumé : A dynamic model for a complete urea granulation circuit is presented in this work. The flowsheet includes a fluidized bed granulator, a cooling unit, a vibrating double-deck screen, and a double-roll crusher. This contribution is based on mathematical models for all the equipments, some of them previous validated against industrial data. All the units are modeled by means of the population balance equation (PBE). In addition, the granulator energy and mass balances for urea and air (used as a cooling medium and fluidization agent) are solved simultaneously with the PBE to properly represent the unit dynamics. Furthermore, mass, energy, and population balances are developed for the cooler. The individual units are successfully integrated under the gPROMS Model Builder Environment, which allows one to have a powerful tool for the circuit simulation and optimization. A sensitivity analysis is performed by running several dynamic and steady-state gPROMS simulations in order to evaluate the influence of different operating variables on the particle size distributions and mass flow rates of the circuit streams, as well as the mass holdup and thermal conditions in the granulator and cooler. The results indicate that both screen deck apertures, together with the crusher lower gap, are the variables that most affect the circuit performance. The circuit stability is also analyzed. Finally, different optimization scenarios are carried out to determine the values of the selected manipulated variables that maximize production on specification, minimize the recycle fraction, and allow a plant revamping. The urea granulation process simulator (including mass, energy, and population balances) constitutes a powerful tool to study the circuit responses under different disturbances, determine the optimal combination of operating and design variables in order to meet the production requirements and explore new process flow diagrams. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901885x [article] Dynamic simulation and optimization of a urea granulation circuit [texte imprimé] / Ivana M. Cotabarren, Auteur ; Diego Bertín, Auteur ; José Romagnoli, Auteur . - 2010 . - pp. 6630–6640. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 14 (Juillet 2010) . - pp. 6630–6640 Mots-clés : Granulation  circuit Résumé : A dynamic model for a complete urea granulation circuit is presented in this work. The flowsheet includes a fluidized bed granulator, a cooling unit, a vibrating double-deck screen, and a double-roll crusher. This contribution is based on mathematical models for all the equipments, some of them previous validated against industrial data. All the units are modeled by means of the population balance equation (PBE). In addition, the granulator energy and mass balances for urea and air (used as a cooling medium and fluidization agent) are solved simultaneously with the PBE to properly represent the unit dynamics. Furthermore, mass, energy, and population balances are developed for the cooler. The individual units are successfully integrated under the gPROMS Model Builder Environment, which allows one to have a powerful tool for the circuit simulation and optimization. A sensitivity analysis is performed by running several dynamic and steady-state gPROMS simulations in order to evaluate the influence of different operating variables on the particle size distributions and mass flow rates of the circuit streams, as well as the mass holdup and thermal conditions in the granulator and cooler. The results indicate that both screen deck apertures, together with the crusher lower gap, are the variables that most affect the circuit performance. The circuit stability is also analyzed. Finally, different optimization scenarios are carried out to determine the values of the selected manipulated variables that maximize production on specification, minimize the recycle fraction, and allow a plant revamping. The urea granulation process simulator (including mass, energy, and population balances) constitutes a powerful tool to study the circuit responses under different disturbances, determine the optimal combination of operating and design variables in order to meet the production requirements and explore new process flow diagrams. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901885x

Modeling of an industrial vibrating double-deck screen of a urea granulation circuit / Ivana M. Cotabarren 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. 3187–3196 Titre : Modeling of an industrial vibrating double-deck screen of a urea granulation circuit Type de document : texte imprimé Auteurs : Ivana M. Cotabarren, Auteur ; José Rossit, Auteur ; Verónica Bucalá, Auteur Année de publication : 2009 Article en page(s) : pp. 3187–3196 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Double-deck  screens  Urea  granulation  circuit  Screening  performance Résumé : A reliable mathematical model to predict the performance of double-deck screens from an industrial urea granulation circuit is provided in this work. The classification in each deck was described by the empirical model reported by Karra [Karra, V. K.Development of a Model for Predicting the Screening Performance of a Vibrating Screen. CIM Bull. 1979, 72, 804.] for the mining industry. The estimation of model parameters was based on industrial data collected from two large-scale double-deck screens belonging to a urea granulation plant. Prior to parameter fitting, data reconciliation of the solid streams was performed, with the aim of determining the unmeasured mass flows and the reconciled particle size distributions that fulfill the material balances for every size class. The results indicate that the fitted model reproduces in an accurate way the performance of the urea granules classification device. Thus, the screen mathematical representation can be used as a module of a plant simulator for many existing urea granulation circuits, which (independently of the technology) have similar industrial vibrating double-deck screens to attain the marketable product granulometry. In addition, the fitted model allows finding the optimal screen apertures to achieve the desired product attributes and recycle ratios. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800968y [article] Modeling of an industrial vibrating double-deck screen of a urea granulation circuit [texte imprimé] / Ivana M. Cotabarren, Auteur ; José Rossit, Auteur ; Verónica Bucalá, Auteur . - 2009 . - pp. 3187–3196. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3187–3196 Mots-clés : Double-deck  screens  Urea  granulation  circuit  Screening  performance Résumé : A reliable mathematical model to predict the performance of double-deck screens from an industrial urea granulation circuit is provided in this work. The classification in each deck was described by the empirical model reported by Karra [Karra, V. K.Development of a Model for Predicting the Screening Performance of a Vibrating Screen. CIM Bull. 1979, 72, 804.] for the mining industry. The estimation of model parameters was based on industrial data collected from two large-scale double-deck screens belonging to a urea granulation plant. Prior to parameter fitting, data reconciliation of the solid streams was performed, with the aim of determining the unmeasured mass flows and the reconciled particle size distributions that fulfill the material balances for every size class. The results indicate that the fitted model reproduces in an accurate way the performance of the urea granules classification device. Thus, the screen mathematical representation can be used as a module of a plant simulator for many existing urea granulation circuits, which (independently of the technology) have similar industrial vibrating double-deck screens to attain the marketable product granulometry. In addition, the fitted model allows finding the optimal screen apertures to achieve the desired product attributes and recycle ratios. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800968y