An extended formulation for the flexible short-term scheduling of multiproduct semicontinuous plants / Elisabet Capon-Garcia in Industrial & engineering chemistry research, Vol. 48 N°4 (Février 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - p. 2009–2019 Titre : An extended formulation for the flexible short-term scheduling of multiproduct semicontinuous plants Type de document : texte imprimé Auteurs : Elisabet Capon-Garcia, Auteur ; Sergio Ferrer-Nadal, Auteur ; Moisès Graells, Auteur Année de publication : 2009 Article en page(s) : p. 2009–2019 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Semicontinuous plants Flexible environments Résumé : Chemical plants are moving toward more-flexible environments, to adapt faster to market changes. For the sake of this flexibility, batch and continuous units might be integrated and operated along the same processing route in a semicontinuous mode, featured by production campaigns of finite duration. Constant production rates for the entire operation have been usually considered. Thus, production adjustments were achieved through storage resources, production line stops, and multiple product campaigns. The objective of this work is to improve the production schedules by developing a new concept for flexible manufacturing, which allows one to program production rate profiles within each semicontinuous operation campaign. Hence, the extended formulation presented allows to address the tradeoff between the opportunities that may arise when adjusting processing rates and the storage needs and opportunities. Finally, several case studies show that the proposed adjustment of the processing rates leads to less storage utilization and more-efficient production performance. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800539f [article] An extended formulation for the flexible short-term scheduling of multiproduct semicontinuous plants [texte imprimé] / Elisabet Capon-Garcia, Auteur ; Sergio Ferrer-Nadal, Auteur ; Moisès Graells, Auteur . - 2009 . - p. 2009–2019. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - p. 2009–2019 Mots-clés : Semicontinuous plants Flexible environments Résumé : Chemical plants are moving toward more-flexible environments, to adapt faster to market changes. For the sake of this flexibility, batch and continuous units might be integrated and operated along the same processing route in a semicontinuous mode, featured by production campaigns of finite duration. Constant production rates for the entire operation have been usually considered. Thus, production adjustments were achieved through storage resources, production line stops, and multiple product campaigns. The objective of this work is to improve the production schedules by developing a new concept for flexible manufacturing, which allows one to program production rate profiles within each semicontinuous operation campaign. Hence, the extended formulation presented allows to address the tradeoff between the opportunities that may arise when adjusting processing rates and the storage needs and opportunities. Finally, several case studies show that the proposed adjustment of the processing rates leads to less storage utilization and more-efficient production performance. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800539f

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Material Transfer Operations in Batch Scheduling / Sergio Ferrer-Nadal in Industrial & engineering chemistry research, Vol. 47 N°20 (Octobre 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N°20 (Octobre 2008) . - P. 7721-7732 Titre : Material Transfer Operations in Batch Scheduling : a critical modeling issue Type de document : texte imprimé Auteurs : Sergio Ferrer-Nadal, Auteur ; Elisabet Capon-Garcia, Auteur ; Carlos A. Méndez, Auteur ; Puigjaner, Luis, Auteur Année de publication : 2008 Article en page(s) : P. 7721-7732 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Batch Scheduling mixed-integer linear programming (MILP) Résumé : An effective short-term scheduling formulation must simultaneously deal with several problem difficulties commonly arising in batch processes operations. One of the key features to be considered is the representation of the material transfer operations between process stages. A nonzero time as well as certain conditions and resources are always required to move the material from one processing stage to the next one according to the specified product recipe. The transfer task consumes a period of time during which a proper synchronization of the equipment units supplying and receiving the material is enforced. Synchronization implies that during the execution of the transfer task, one unit will be supplying the material whereas the other one will be receiving it and consequently, no other task can be simultaneously performed in both units. Most of the existing mixed-integer linear programming (MILP) optimization approaches have traditionally dealt with the batch scheduling problem assuming zero transfer times, and consequently no synchronization, between consecutive processing stages. Simplification relying on negligible transfer times may work properly for the scheduling of multiproduct batch plants with similar product recipes; however, it is demonstrated in this work that ignoring the important role of transfer times may seriously compromise the feasibility of the scheduling whenever shared units and storage tanks, material recycles, or bidirectional flows of products are to be considered. To overcome the serious limitations of current MILP-based scheduling approaches, a general precedence-based framework accounting for nonzero transfer times is introduced. Also, two alternative methods that avoid generating unfeasible schedules are proposed and tested in different case studies. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800075u [article] Material Transfer Operations in Batch Scheduling : a critical modeling issue [texte imprimé] / Sergio Ferrer-Nadal, Auteur ; Elisabet Capon-Garcia, Auteur ; Carlos A. Méndez, Auteur ; Puigjaner, Luis, Auteur . - 2008 . - P. 7721-7732. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°20 (Octobre 2008) . - P. 7721-7732 Mots-clés : Batch Scheduling mixed-integer linear programming (MILP) Résumé : An effective short-term scheduling formulation must simultaneously deal with several problem difficulties commonly arising in batch processes operations. One of the key features to be considered is the representation of the material transfer operations between process stages. A nonzero time as well as certain conditions and resources are always required to move the material from one processing stage to the next one according to the specified product recipe. The transfer task consumes a period of time during which a proper synchronization of the equipment units supplying and receiving the material is enforced. Synchronization implies that during the execution of the transfer task, one unit will be supplying the material whereas the other one will be receiving it and consequently, no other task can be simultaneously performed in both units. Most of the existing mixed-integer linear programming (MILP) optimization approaches have traditionally dealt with the batch scheduling problem assuming zero transfer times, and consequently no synchronization, between consecutive processing stages. Simplification relying on negligible transfer times may work properly for the scheduling of multiproduct batch plants with similar product recipes; however, it is demonstrated in this work that ignoring the important role of transfer times may seriously compromise the feasibility of the scheduling whenever shared units and storage tanks, material recycles, or bidirectional flows of products are to be considered. To overcome the serious limitations of current MILP-based scheduling approaches, a general precedence-based framework accounting for nonzero transfer times is introduced. Also, two alternative methods that avoid generating unfeasible schedules are proposed and tested in different case studies. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800075u

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