## Publicaciones

## 1995 |

J. Espinosa, P.A. Aguirre, G. Pérez Some aspects in the design of multicomponent reactive distillation columns including nonreactive species (Artículo de revista) Chemical Engineering Science, 50 (3), pp. 469-484, 1995, (cited By 25). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Espinosa1995469, title = {Some aspects in the design of multicomponent reactive distillation columns including nonreactive species}, author = { J. Espinosa and P.A. Aguirre and G. Pérez}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0029251343&partnerID=40&md5=6703250f6b2df063aac5dc484738fe40}, doi = {10.1016/0009-2509(94)00258-S}, year = {1995}, date = {1995-01-01}, journal = {Chemical Engineering Science}, volume = {50}, number = {3}, pages = {469-484}, abstract = {Some aspects related to the design of reactive distillation columns are addressed in this paper. A new set of transformed composition variables is proposed for mixtures including one or more components that are inert under the process conditions. This set corresponds to an extension of that suggested by Barbosa and Doherty (1988a, Chem. Engng Sci. 43, 1523-1537) and allows to compute by means of any traditional procedure, the concentration profiles along the column and therefore, the minimum reflux ratio. The compositions of product streams of a reactive distillation column are subject to constraints of thermodynamic nature that can be determined before any attempt to design the column. These thermodynamic constraints do not have a counterpart in conventional distillation and become an essential piece of information in order to select the design variables and specify their values. A parametric analysis of the simultaneous chemical reaction and liquid-vapor equilibrium is suggested as a very useful instrument to select thermodynamically feasible design specifications. In this work, we also present an initial discussion about possible columns sequences to obtain the reaction product free of inert species. The selection and calculation of the relevant variables that are common in the first steps of the design and synthesis of reactive distillation processes are discussed through examples. Finally, throughout the entire paper several interesting physical and operational conclusions regarding inert components in reactive distillation are given. The main conclusion is that the inerts play a key role in the design of a reactive column. © 1995.}, note = {cited By 25}, keywords = {}, pubstate = {published}, tppubtype = {article} } Some aspects related to the design of reactive distillation columns are addressed in this paper. A new set of transformed composition variables is proposed for mixtures including one or more components that are inert under the process conditions. This set corresponds to an extension of that suggested by Barbosa and Doherty (1988a, Chem. Engng Sci. 43, 1523-1537) and allows to compute by means of any traditional procedure, the concentration profiles along the column and therefore, the minimum reflux ratio. The compositions of product streams of a reactive distillation column are subject to constraints of thermodynamic nature that can be determined before any attempt to design the column. These thermodynamic constraints do not have a counterpart in conventional distillation and become an essential piece of information in order to select the design variables and specify their values. A parametric analysis of the simultaneous chemical reaction and liquid-vapor equilibrium is suggested as a very useful instrument to select thermodynamically feasible design specifications. In this work, we also present an initial discussion about possible columns sequences to obtain the reaction product free of inert species. The selection and calculation of the relevant variables that are common in the first steps of the design and synthesis of reactive distillation processes are discussed through examples. Finally, throughout the entire paper several interesting physical and operational conclusions regarding inert components in reactive distillation are given. The main conclusion is that the inerts play a key role in the design of a reactive column. © 1995. |

## 1994 |

J. Espinosa, E.C. Martínez, G. Perez Dynamic behavior of reactive distillation columns. Equilibrium systems (Artículo de revista) Chemical Engineering Communications, 128 , pp. 19-42, 1994, (cited By 13). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Espinosa199419, title = {Dynamic behavior of reactive distillation columns. Equilibrium systems}, author = { J. Espinosa and E.C. Martínez and G. Perez}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0028166689&partnerID=40&md5=b38f91217d2f9f9db183bb92850d48cb}, year = {1994}, date = {1994-01-01}, journal = {Chemical Engineering Communications}, volume = {128}, pages = {19-42}, abstract = {This paper deals with the dynamic behavior of simultaneous reaction-separation systems which operate at or near the chemical equilibrium in the liquid phase. The process under study comprises a whole set of 'instantaneous', and very fast reversible reactions where the difference in volatilities favors both the progress of reaction and product separation. The main aim of our study is to gain a deeper understanding of the dynamic behavior of distillation columns by using a model that is simple and efficient, yet informative. This kind of model is outstanding for synthesis and design of control schemes which require a careful modelling and understanding of process response to different changes in the environment. We use a suitable transformation of variables (after Barbosa and Doherty, 1988b) in order to define a new set of state variables; as a result, the balance equations become identical to those for conventional distillation. Also, an efficient physicochemical algorithm that can handle both the original and new state variables is used. Thus, a composition-holdup dynamic model is simulated in the 'transformed field' using a stage-by-stage approach. To further reduce computational time, the transformed problem has also been solved by means of a reduction procedure based on approximating by orthogonal polynomials the transformed composition and flow profiles in the column. The performance of the two proposed methods are compared by using the top section of a quaternary reactive column. The results obtained shown that reactive distillation dynamics has certain peculiarities derived from superimposing reaction and separation phenomena.}, note = {cited By 13}, keywords = {}, pubstate = {published}, tppubtype = {article} } This paper deals with the dynamic behavior of simultaneous reaction-separation systems which operate at or near the chemical equilibrium in the liquid phase. The process under study comprises a whole set of 'instantaneous', and very fast reversible reactions where the difference in volatilities favors both the progress of reaction and product separation. The main aim of our study is to gain a deeper understanding of the dynamic behavior of distillation columns by using a model that is simple and efficient, yet informative. This kind of model is outstanding for synthesis and design of control schemes which require a careful modelling and understanding of process response to different changes in the environment. We use a suitable transformation of variables (after Barbosa and Doherty, 1988b) in order to define a new set of state variables; as a result, the balance equations become identical to those for conventional distillation. Also, an efficient physicochemical algorithm that can handle both the original and new state variables is used. Thus, a composition-holdup dynamic model is simulated in the 'transformed field' using a stage-by-stage approach. To further reduce computational time, the transformed problem has also been solved by means of a reduction procedure based on approximating by orthogonal polynomials the transformed composition and flow profiles in the column. The performance of the two proposed methods are compared by using the top section of a quaternary reactive column. The results obtained shown that reactive distillation dynamics has certain peculiarities derived from superimposing reaction and separation phenomena. |

O.A. Iribarren, M.F. Malone, H.E. Salomone Heuristic approach for the design of hybrid batch-continuous processes (Artículo de revista) Chemical Engineering Research and Design, 72 (A3), pp. 295-306, 1994, (cited By 1). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Iribarren1994295, title = {Heuristic approach for the design of hybrid batch-continuous processes}, author = { O.A. Iribarren and M.F. Malone and H.E. Salomone}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0028427205&partnerID=40&md5=4f044977d8f59d0cb8b8675bc9cf3d47}, year = {1994}, date = {1994-01-01}, journal = {Chemical Engineering Research and Design}, volume = {72}, number = {A3}, pages = {295-306}, abstract = {This paper presents a procedure for the selection of batch or continuous type stages in single product chemical processes, highlighting the effects of the production rate. Batch designs allow the merging of conformable tasks (reactions or separations) in single units, and this becomes attractive economically for small size equipment for which the economy of scale is stronger. The procedure is heuristic, and consists of a sequence of decisions that reduces the number of alternatives to be searched to find a good design. At each step of the search, more compact batch designs are considered (designs with a smaller number of stages). The unconstrained optimization of all batch alternatives over the process decision variables, provides information which can be used to eliminate many alternatives and point out attractive mergings. The procedure is illustrated for a process to produce butadiene sulfone.}, note = {cited By 1}, keywords = {}, pubstate = {published}, tppubtype = {article} } This paper presents a procedure for the selection of batch or continuous type stages in single product chemical processes, highlighting the effects of the production rate. Batch designs allow the merging of conformable tasks (reactions or separations) in single units, and this becomes attractive economically for small size equipment for which the economy of scale is stronger. The procedure is heuristic, and consists of a sequence of decisions that reduces the number of alternatives to be searched to find a good design. At each step of the search, more compact batch designs are considered (designs with a smaller number of stages). The unconstrained optimization of all batch alternatives over the process decision variables, provides information which can be used to eliminate many alternatives and point out attractive mergings. The procedure is illustrated for a process to produce butadiene sulfone. |

H.E. Salomone, J.M. Montagna, O.A. Iribarren Dynamic simulations in the design of batch processes (Artículo de revista) Computers and Chemical Engineering, 18 (3), pp. 191-204, 1994, (cited By 26). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Salomone1994191, title = {Dynamic simulations in the design of batch processes}, author = { H.E. Salomone and J.M. Montagna and O.A. Iribarren}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0028144097&partnerID=40&md5=f0d99a3da98dbaed6197c19889077b77}, doi = {10.1016/0098-1354(94)85008-9}, year = {1994}, date = {1994-01-01}, journal = {Computers and Chemical Engineering}, volume = {18}, number = {3}, pages = {191-204}, abstract = {This paper presents a conceptual procedure for the modeling of batch plants with posynomial expressions, and a resolution strategy for the optimization of the process decision variables, where dynamic simulation provides the parameters for the analytical posynomial expressions. With this resolution sequence, the optimization of the process decision variables remains affordable and trouble-free. © 1994.}, note = {cited By 26}, keywords = {}, pubstate = {published}, tppubtype = {article} } This paper presents a conceptual procedure for the modeling of batch plants with posynomial expressions, and a resolution strategy for the optimization of the process decision variables, where dynamic simulation provides the parameters for the analytical posynomial expressions. With this resolution sequence, the optimization of the process decision variables remains affordable and trouble-free. © 1994. |

J.M. Montagna, O.A. Iribarren, F.C. Galiano Design of multiproduct batch plants with process performance models (Artículo de revista) Chemical Engineering Research and Design, 72 (A6), pp. 783-791, 1994, (cited By 13). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Montagna1994783, title = {Design of multiproduct batch plants with process performance models}, author = { J.M. Montagna and O.A. Iribarren and F.C. Galiano}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0028539761&partnerID=40&md5=7c324f9c7c25eb9d3c7c63e3e59220d2}, year = {1994}, date = {1994-01-01}, journal = {Chemical Engineering Research and Design}, volume = {72}, number = {A6}, pages = {783-791}, abstract = {A model is presented for the optimal design of multiproduct batch plants, which uses process performance information. The process description resembles the familiar posynomial model for sizes and cycle times. While the former approaches considered constant values for the size and cycle time factors, they are considered here as functions of a set of process variables. The results obtained show significantly improved solutions with this model, when typical chemical engineering unit operations are involved. Operating costs are naturally included.}, note = {cited By 13}, keywords = {}, pubstate = {published}, tppubtype = {article} } A model is presented for the optimal design of multiproduct batch plants, which uses process performance information. The process description resembles the familiar posynomial model for sizes and cycle times. While the former approaches considered constant values for the size and cycle time factors, they are considered here as functions of a set of process variables. The results obtained show significantly improved solutions with this model, when typical chemical engineering unit operations are involved. Operating costs are naturally included. |

## 1993 |

N.J. Scenna, P.A. Aguirre Thermodynamic methodology for process synthesis and its application to dual-purpose desalination plants. Entraction vs. back pressure turbines (Artículo de revista) Chemical Engineering Research and Design, 71 (A1), pp. 77-84, 1993, (cited By 2). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Scenna199377, title = {Thermodynamic methodology for process synthesis and its application to dual-purpose desalination plants. Entraction vs. back pressure turbines}, author = { N.J. Scenna and P.A. Aguirre}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0027333856&partnerID=40&md5=92d9aaac5c0647f5d3a60d9de10734be}, year = {1993}, date = {1993-01-01}, journal = {Chemical Engineering Research and Design}, volume = {71}, number = {A1}, pages = {77-84}, abstract = {A set of thermodynamically non-ideal optimal solutions is obtained for each amount of investment determined by the items used (heat transfer areas, turbines efficiencies and capacities, etc.) when either a back pressure and a condensation turbine or an extraction-condensation turbine coupled to a desalination process in analysed. The procedure to obtain optimal structures and operating conditions is based on the synthesis theory presented in previous papers. The solutions obtained form a basis for the selection of those alternatives which satisfy economical optimum and process functional criteria.}, note = {cited By 2}, keywords = {}, pubstate = {published}, tppubtype = {article} } A set of thermodynamically non-ideal optimal solutions is obtained for each amount of investment determined by the items used (heat transfer areas, turbines efficiencies and capacities, etc.) when either a back pressure and a condensation turbine or an extraction-condensation turbine coupled to a desalination process in analysed. The procedure to obtain optimal structures and operating conditions is based on the synthesis theory presented in previous papers. The solutions obtained form a basis for the selection of those alternatives which satisfy economical optimum and process functional criteria. |

J.M. Montagna Problem-oriented modules for process simulation. Resolution strategies for simulation and optimization (Artículo de revista) Canadian Journal of Chemical Engineering, 71 (4), pp. 634-641, 1993, (cited By 1). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Montagna1993634, title = {Problem-oriented modules for process simulation. Resolution strategies for simulation and optimization}, author = { J.M. Montagna}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0027643121&partnerID=40&md5=ae9d0a376c7211b2c31dc739b1e7f224}, year = {1993}, date = {1993-01-01}, journal = {Canadian Journal of Chemical Engineering}, volume = {71}, number = {4}, pages = {634-641}, abstract = {A new resolution strategy is presented to overcome short-comings of the sequential modular process flowsheeting. Following a logic flow of information, different from the material flow of streams in the flowsheet, changes the mathematical structure of the system of equations that models the units. New programs have been generated, very different from traditional modules. Deciding an appropriate resolution strategy usually leads to a dramatic reduction in required CPU times and to an increased flexibility to handle different problems. The simulation convergence and process optimization can be approached from a different perspective.}, note = {cited By 1}, keywords = {}, pubstate = {published}, tppubtype = {article} } A new resolution strategy is presented to overcome short-comings of the sequential modular process flowsheeting. Following a logic flow of information, different from the material flow of streams in the flowsheet, changes the mathematical structure of the system of equations that models the units. New programs have been generated, very different from traditional modules. Deciding an appropriate resolution strategy usually leads to a dramatic reduction in required CPU times and to an increased flexibility to handle different problems. The simulation convergence and process optimization can be approached from a different perspective. |

F.C. Galiano, J.M. Montagna Optimal allocation of intermediate storage in multiproduct batch chemical plants (Artículo de revista) Mathematical and Computer Modelling, 18 (9), pp. 111-129, 1993, (cited By 3). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Galiano1993111, title = {Optimal allocation of intermediate storage in multiproduct batch chemical plants}, author = { F.C. Galiano and J.M. Montagna}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-3042999327&partnerID=40&md5=f8cfcb63921a9bbd8c9212baa883b35e}, doi = {10.1016/0895-7177(93)90147-Q}, year = {1993}, date = {1993-01-01}, journal = {Mathematical and Computer Modelling}, volume = {18}, number = {9}, pages = {111-129}, abstract = {A procedure is presented for the preliminary design of multiproduct batch chemical processes that takes into account the provision of intermediate storage. It finds the position where the storage tanks have to be placed, which may change depending on the product being produced at each time, and the sizes of production units and tanks that minimize the plant investment cost. Two approaches are used: a rigorous algorithm that resorts to integer programming, and a heuristic approach with quite a good performance. Results obtained with a low computational effort show significant reductions in the investment cost if the storage tanks are properly allocated, depending on the product being processed. © 1993.}, note = {cited By 3}, keywords = {}, pubstate = {published}, tppubtype = {article} } A procedure is presented for the preliminary design of multiproduct batch chemical processes that takes into account the provision of intermediate storage. It finds the position where the storage tanks have to be placed, which may change depending on the product being produced at each time, and the sizes of production units and tanks that minimize the plant investment cost. Two approaches are used: a rigorous algorithm that resorts to integer programming, and a heuristic approach with quite a good performance. Results obtained with a low computational effort show significant reductions in the investment cost if the storage tanks are properly allocated, depending on the product being processed. © 1993. |

## 1992 |

E.C. Martínez, L. Beltramini, H.P. Leone, C.A. Ruiz, E. Huete Knowledge elicitation and structuring for a real-time expert system for monitoring a butadiene extraction system (Artículo de revista) Computers and Chemical Engineering, 16 (1), pp. S345-S352, 1992, (cited By 0). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Martinez1992, title = {Knowledge elicitation and structuring for a real-time expert system for monitoring a butadiene extraction system}, author = { E.C. Martínez and L. Beltramini and H.P. Leone and C.A. Ruiz and E. Huete}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0026459132&partnerID=40&md5=e096c0f6099c74c901527e1ec1cd6443}, year = {1992}, date = {1992-01-01}, journal = {Computers and Chemical Engineering}, volume = {16}, number = {1}, pages = {S345-S352}, abstract = {A real-time expert system for monitoring a butadiene purification process it has been developed using ONSPEC™ data acquisition and data processing capabilities. In this paper, the monitoring activities are focused on the two core columns: an extractive distillation column and a solvent stripping column working together in a highly integrated manner through material recycling and energy recovery. The paper emphasizes the steps followed during knowledge elicitation and organization, as well as the interrelation with the expert during these processes. The knowledge elicitation methodology has been mostly devised in a top-down style using HAZOP (HAZard and OPerability analysis), CCA (Cause and Consequence Analysis) and FMEA (Failure Mode and Effect Analysis) techniques. These methodologies provide an efficient means for motivating the experts to think aloud, from a more abstract to a more detailed level of process state understanding, about operational problems and actions or recommendations to restore control and performance. The knowledge acquired has been chunked into sets of rules which are coordinated by a core chunk using a "token-ring" style. This architecture proved to be successful for working in a real-time environment and from the point of view of the expert system expansion. A monitoring real-time expert system has been developed. It consists at present, in around 70 detection blocks (mainly operator recommendations and warnings) and 90 rules, a few number of simplified material and energy balances based on real time data and plant operational manual displayed on-line. During the development of this system, reliability engineering techniques, like HAZOP and FMEA, proved to be very useful tools in the stages of knowledge elicitation, conceptualization and formalization. Issues related to expert knowledge organization in a real-time environment were also discussed. In particular, a time-scale hierarchy permits a well-balanced workload on the monitoring activities. Also, token-ring coordination for different subjects of knowledge takes care of process interactions. © 1992.}, note = {cited By 0}, keywords = {}, pubstate = {published}, tppubtype = {article} } A real-time expert system for monitoring a butadiene purification process it has been developed using ONSPEC™ data acquisition and data processing capabilities. In this paper, the monitoring activities are focused on the two core columns: an extractive distillation column and a solvent stripping column working together in a highly integrated manner through material recycling and energy recovery. The paper emphasizes the steps followed during knowledge elicitation and organization, as well as the interrelation with the expert during these processes. The knowledge elicitation methodology has been mostly devised in a top-down style using HAZOP (HAZard and OPerability analysis), CCA (Cause and Consequence Analysis) and FMEA (Failure Mode and Effect Analysis) techniques. These methodologies provide an efficient means for motivating the experts to think aloud, from a more abstract to a more detailed level of process state understanding, about operational problems and actions or recommendations to restore control and performance. The knowledge acquired has been chunked into sets of rules which are coordinated by a core chunk using a "token-ring" style. This architecture proved to be successful for working in a real-time environment and from the point of view of the expert system expansion. A monitoring real-time expert system has been developed. It consists at present, in around 70 detection blocks (mainly operator recommendations and warnings) and 90 rules, a few number of simplified material and energy balances based on real time data and plant operational manual displayed on-line. During the development of this system, reliability engineering techniques, like HAZOP and FMEA, proved to be very useful tools in the stages of knowledge elicitation, conceptualization and formalization. Issues related to expert knowledge organization in a real-time environment were also discussed. In particular, a time-scale hierarchy permits a well-balanced workload on the monitoring activities. Also, token-ring coordination for different subjects of knowledge takes care of process interactions. © 1992. |

H.E. Salomone, O.A. Iribarren Posynomial modeling of batch plants: A procedure to include process decision variables (Artículo de revista) Computers and Chemical Engineering, 16 (3), pp. 173-184, 1992, (cited By 26). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Salomone1992173, title = {Posynomial modeling of batch plants: A procedure to include process decision variables}, author = { H.E. Salomone and O.A. Iribarren}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0026833195&partnerID=40&md5=cad2be9456bac58e2364c4b13190999d}, doi = {10.1016/0098-1354(92)85004-R}, year = {1992}, date = {1992-01-01}, journal = {Computers and Chemical Engineering}, volume = {16}, number = {3}, pages = {173-184}, abstract = {A general procedure for the generation of posynomial models of batch plants is presented. Posynomial models describe process stages with size factors and cycle times, allowing the synthesis and sizing of batch plants through well-established literature developments. Starting from modular process design equations, proper algebraic manipulation defines size factors and cycle times which are functions of process decision variables. A performance index optimization on those variables, with a decoupling level of intermediate storage, provides a posynomial model for the process. A citric acid fermentative process is modeled as an example. © 1992.}, note = {cited By 26}, keywords = {}, pubstate = {published}, tppubtype = {article} } A general procedure for the generation of posynomial models of batch plants is presented. Posynomial models describe process stages with size factors and cycle times, allowing the synthesis and sizing of batch plants through well-established literature developments. Starting from modular process design equations, proper algebraic manipulation defines size factors and cycle times which are functions of process decision variables. A performance index optimization on those variables, with a decoupling level of intermediate storage, provides a posynomial model for the process. A citric acid fermentative process is modeled as an example. © 1992. |

J. Koehler, P.A. Aguirre, E. Blass Evolutionary thermodynamic synthesis of zeotropic distillation sequences (Artículo de revista) Gas Separation and Purification, 6 (3), pp. 153-167, 1992, (cited By 17). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Koehler1992153, title = {Evolutionary thermodynamic synthesis of zeotropic distillation sequences}, author = { J. Koehler and P.A. Aguirre and E. Blass}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0000784538&partnerID=40&md5=581beeae6cda6fea3684cd8a23ab29e3}, doi = {10.1016/0950-4214(92)80015-B}, year = {1992}, date = {1992-01-01}, journal = {Gas Separation and Purification}, volume = {6}, number = {3}, pages = {153-167}, abstract = {The objective of this paper is to present a new evolutionary strategy for the synthesis of simple and complex distillation sequences. The initial flowsheet is the reversible multicomponent distillation scheme, which includes as the thermodynamically optimum superstructure many of the possible separation configurations. Assumptions with respect to ideal boiling behaviour or constant molar overflow are not required, but azeotropic systems are excluded. The computation time requirement is extremely low, because only flash-type calculations and no rigorous column simulations are involved. In this approach columns and heat exchangers are successively removed from the initial flowsheet by using thermodynamic information on splits. In this way not only simple sequences, but also sidestream withdrawals, sidestream strippers and sidestream enrichers can be created. The evolutionary strategy and the underlying modification criteria will be illustrated by several examples. Some comments on common heuristic rules and heat-integration possibilities are made in conclusion. © 1992.}, note = {cited By 17}, keywords = {}, pubstate = {published}, tppubtype = {article} } The objective of this paper is to present a new evolutionary strategy for the synthesis of simple and complex distillation sequences. The initial flowsheet is the reversible multicomponent distillation scheme, which includes as the thermodynamically optimum superstructure many of the possible separation configurations. Assumptions with respect to ideal boiling behaviour or constant molar overflow are not required, but azeotropic systems are excluded. The computation time requirement is extremely low, because only flash-type calculations and no rigorous column simulations are involved. In this approach columns and heat exchangers are successively removed from the initial flowsheet by using thermodynamic information on splits. In this way not only simple sequences, but also sidestream withdrawals, sidestream strippers and sidestream enrichers can be created. The evolutionary strategy and the underlying modification criteria will be illustrated by several examples. Some comments on common heuristic rules and heat-integration possibilities are made in conclusion. © 1992. |

## 1991 |

M.R. Galli, J. Cerdá Synthesis of flexible heat exchanger networks-III. Temperature and flowrate variations (Artículo de revista) Computers and Chemical Engineering, 15 (1), pp. 7-24, 1991, (cited By 19). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Galli19917, title = {Synthesis of flexible heat exchanger networks-III. Temperature and flowrate variations}, author = { M.R. Galli and J. Cerdá}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0025824943&partnerID=40&md5=1531738ef5d9b06de495de8e3f823fc2}, doi = {10.1016/0098-1354(91)87002-Q}, year = {1991}, date = {1991-01-01}, journal = {Computers and Chemical Engineering}, volume = {15}, number = {1}, pages = {7-24}, abstract = {A general algorithmic approach to the synthesis of flexible heat exchanger networks which explicitly accounts for prespecified uncertainties in both supply temperatures and flowrates is presented. The synthesis procedure includes four major steps: (1) an LP transshipment problem is developed to discover a usually small discrete set of dominant pinch points controlling the network design; (2) knowledge of the dominant pinch set permits to derive an MILP formulation that provides an optimal network at the level of units. An iterative scheme is not necessary because the proposed mathematical modelling includes explicit flexibility constraints; (3) the set of design conditions for the synthesis of the whole network at the level of structure is established through the use of an MILP pinch-"jump" test. Appropriate design points, usually a single one, are assigned to each subnetwork; and (4) the structure of every subnetwork is sequentially found by often using a synthesis technique for fixed stream conditions (Floudas et al., AIChE Jl 32, 276; 1986). Selection of heat exchanger areas is not addressed in this paper. Four examples involving temperature and flowrate disturbances have been successfully solved in a short computer time. No deterioration in the computational efficiency of the algorithm has been observed as the number of uncertainties increases. © 1991.}, note = {cited By 19}, keywords = {}, pubstate = {published}, tppubtype = {article} } A general algorithmic approach to the synthesis of flexible heat exchanger networks which explicitly accounts for prespecified uncertainties in both supply temperatures and flowrates is presented. The synthesis procedure includes four major steps: (1) an LP transshipment problem is developed to discover a usually small discrete set of dominant pinch points controlling the network design; (2) knowledge of the dominant pinch set permits to derive an MILP formulation that provides an optimal network at the level of units. An iterative scheme is not necessary because the proposed mathematical modelling includes explicit flexibility constraints; (3) the set of design conditions for the synthesis of the whole network at the level of structure is established through the use of an MILP pinch-"jump" test. Appropriate design points, usually a single one, are assigned to each subnetwork; and (4) the structure of every subnetwork is sequentially found by often using a synthesis technique for fixed stream conditions (Floudas et al., AIChE Jl 32, 276; 1986). Selection of heat exchanger areas is not addressed in this paper. Four examples involving temperature and flowrate disturbances have been successfully solved in a short computer time. No deterioration in the computational efficiency of the algorithm has been observed as the number of uncertainties increases. © 1991. |

O.A. Iribarren, O.J. Chiotti Simplified analytical prediction of distillation column startup time at total reflux (Artículo de revista) Canadian Journal of Chemical Engineering, 69 (1), pp. 377-382, 1991, (cited By 1). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Iribarren1991377, title = {Simplified analytical prediction of distillation column startup time at total reflux}, author = { O.A. Iribarren and O.J. Chiotti}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0026108794&partnerID=40&md5=5c45a0aa9031e437878be3ec59097da6}, year = {1991}, date = {1991-01-01}, journal = {Canadian Journal of Chemical Engineering}, volume = {69}, number = {1}, pages = {377-382}, abstract = {A short-cut explicit expression is presented for distillation at total reflux that predicts the time it takes to shift the reboiler composition from an initial charge composition to the final steady state composition. The prediction is of interest when handling low relative volatility mixtures, as in isomeric or isotopic distillations, where the startups involve times in the order of a day or more.}, note = {cited By 1}, keywords = {}, pubstate = {published}, tppubtype = {article} } A short-cut explicit expression is presented for distillation at total reflux that predicts the time it takes to shift the reboiler composition from an initial charge composition to the final steady state composition. The prediction is of interest when handling low relative volatility mixtures, as in isomeric or isotopic distillations, where the startups involve times in the order of a day or more. |

O.J. Chiotti, O.A. Iribarren Simplified models for binary batch distillation (Artículo de revista) Computers and Chemical Engineering, 15 (1), pp. 1-5, 1991, (cited By 10). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Chiotti19911, title = {Simplified models for binary batch distillation}, author = { O.J. Chiotti and O.A. Iribarren}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0025921369&partnerID=40&md5=a2f112621041e3d3805e6d6dcff53047}, doi = {10.1016/0098-1354(91)87001-P}, year = {1991}, date = {1991-01-01}, journal = {Computers and Chemical Engineering}, volume = {15}, number = {1}, pages = {1-5}, abstract = {The material balances of batch distillation with intermediate cuts to be recycled involve an iterative procedure until reaching a "steady operation" balance. Thus, the rigorous simulation approach to batch distillation optimization is computationally expensive. This work presents approximate models to expedite computer optimization of batch distillations with intermediate cuts, resorting to conventional NLP codes. The operations modeled are rectification and stripping with recycle of the intermediate cut. © 1991.}, note = {cited By 10}, keywords = {}, pubstate = {published}, tppubtype = {article} } The material balances of batch distillation with intermediate cuts to be recycled involve an iterative procedure until reaching a "steady operation" balance. Thus, the rigorous simulation approach to batch distillation optimization is computationally expensive. This work presents approximate models to expedite computer optimization of batch distillations with intermediate cuts, resorting to conventional NLP codes. The operations modeled are rectification and stripping with recycle of the intermediate cut. © 1991. |

N.J. Scenna, P.A. Aguirre Optimal thermodynamic synthesis of dual-purpose desalination plants. Extraction vs. back pressure turbines (Artículo de revista) Desalination, 81 (1-3), pp. 419-436, 1991, (cited By 3). (Enlaces | BibTeX | Etiquetas: ) @article{Scenna1991419, title = {Optimal thermodynamic synthesis of dual-purpose desalination plants. Extraction vs. back pressure turbines}, author = { N.J. Scenna and P.A. Aguirre}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0026191901&partnerID=40&md5=e0d05fc9cfdc48940083280a1e246201}, doi = {10.1016/0011-9164(91)85074-5}, year = {1991}, date = {1991-01-01}, journal = {Desalination}, volume = {81}, number = {1-3}, pages = {419-436}, note = {cited By 3}, keywords = {}, pubstate = {published}, tppubtype = {article} } |

J. Koehler, P.A. Aguirre, E. Blass Minimum reflux calculations for nonideal mixtures using the reversible distillation model (Artículo de revista) Chemical Engineering Science, 46 (12), pp. 3007-3021, 1991, (cited By 71). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Koehler19913007, title = {Minimum reflux calculations for nonideal mixtures using the reversible distillation model}, author = { J. Koehler and P.A. Aguirre and E. Blass}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0026360562&partnerID=40&md5=3f7c936dcd58c93f7b2a7b823652ef90}, doi = {10.1016/0009-2509(91)85005-I}, year = {1991}, date = {1991-01-01}, journal = {Chemical Engineering Science}, volume = {46}, number = {12}, pages = {3007-3021}, abstract = {A new approach for calculating minimum flows in simple distillation columns is presented. Unlike most previous work, no assumptions concerning ideal boiling or enthalpy behavior are required. The computation time is low, because neither rigorous simulation runs nor column iteration procedures are involved, and the method is suited for the evaluation of a large number of distillation sequences in terms of energy consumption at early stages of process design. The basic idea is the description of a distillation column under minimum reflux conditions by means of the reversible distillation model, which will be introduced briefly. The new method has been applied successfully to nonideal and azeotropic systems. Several calculations are illustrated with comparisons both to a rigorous and to the Underwood method. It will also be explained and demonstrated that the prediction and determination of tangent pinch points is a logical extension of the reversible distillation model. © 1991.}, note = {cited By 71}, keywords = {}, pubstate = {published}, tppubtype = {article} } A new approach for calculating minimum flows in simple distillation columns is presented. Unlike most previous work, no assumptions concerning ideal boiling or enthalpy behavior are required. The computation time is low, because neither rigorous simulation runs nor column iteration procedures are involved, and the method is suited for the evaluation of a large number of distillation sequences in terms of energy consumption at early stages of process design. The basic idea is the description of a distillation column under minimum reflux conditions by means of the reversible distillation model, which will be introduced briefly. The new method has been applied successfully to nonideal and azeotropic systems. Several calculations are illustrated with comparisons both to a rigorous and to the Underwood method. It will also be explained and demonstrated that the prediction and determination of tangent pinch points is a logical extension of the reversible distillation model. © 1991. |

N.J. Scenna, P.A. Aguirre Optimal thermodynamic synthesis of dual-purpose desalination plants. Extraction vs. back pressure turbines (Conferencia) 1 (125), 1991, (cited By 1). (Resumen | Enlaces | BibTeX | Etiquetas: ) @conference{Scenna1991419b, title = {Optimal thermodynamic synthesis of dual-purpose desalination plants. Extraction vs. back pressure turbines}, author = { N.J. Scenna and P.A. Aguirre}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0025814077&partnerID=40&md5=bb1d907702506ecedfe8f04cec2c9a21}, year = {1991}, date = {1991-01-01}, journal = {Institution of Chemical Engineers Symposium Series}, volume = {1}, number = {125}, pages = {419-436}, abstract = {The aim of this paper is to apply and adapt the theoretical knowledge of the synthesis theory to dual-purpose desalination systems. If for each amount of investment determined by the items used (heat transfer areas, turbines efficiencies, etc.) it is possible to determine the optimum solution characterized by a maximum thermodynamic efficiency, then a set of thermodynamically non-ideal optimal solutions is obtained, which constitutes a basis for the designer's selection of those which satisfy economical optimum and process functional criteria. This feature is important because the relationship between better energy usage and larger investment costs is a function of geographical and contingent factors, whereas the thermodynamic relationships are not, thus having a general validity.}, note = {cited By 1}, keywords = {}, pubstate = {published}, tppubtype = {conference} } The aim of this paper is to apply and adapt the theoretical knowledge of the synthesis theory to dual-purpose desalination systems. If for each amount of investment determined by the items used (heat transfer areas, turbines efficiencies, etc.) it is possible to determine the optimum solution characterized by a maximum thermodynamic efficiency, then a set of thermodynamically non-ideal optimal solutions is obtained, which constitutes a basis for the designer's selection of those which satisfy economical optimum and process functional criteria. This feature is important because the relationship between better energy usage and larger investment costs is a function of geographical and contingent factors, whereas the thermodynamic relationships are not, thus having a general validity. |

J.M. Montagna, N.J. Scenna, T. Melli Some theoretical aspects in simulation of multiple stage desalination systems (Artículo de revista) Desalination, 81 (1-3), pp. 437-448, 1991, (cited By 7). (Enlaces | BibTeX | Etiquetas: ) @article{Montagna1991437, title = {Some theoretical aspects in simulation of multiple stage desalination systems}, author = { J.M. Montagna and N.J. Scenna and T. Melli}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0026191897&partnerID=40&md5=4f3789a6e890b322d7900c11617d6f7e}, doi = {10.1016/0011-9164(91)85075-6}, year = {1991}, date = {1991-01-01}, journal = {Desalination}, volume = {81}, number = {1-3}, pages = {437-448}, note = {cited By 7}, keywords = {}, pubstate = {published}, tppubtype = {article} } |

J.M. Montagna, N.J. Scenna, T. Melli Some theoretical aspects in simulation of multiple stage desalination systems (Conferencia) 1 (125), 1991, (cited By 0). (Resumen | Enlaces | BibTeX | Etiquetas: ) @conference{Montagna1991437b, title = {Some theoretical aspects in simulation of multiple stage desalination systems}, author = { J.M. Montagna and N.J. Scenna and T. Melli}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0025888237&partnerID=40&md5=7ba558a6359f3d485e12ce7ef4243f3f}, year = {1991}, date = {1991-01-01}, journal = {Institution of Chemical Engineers Symposium Series}, volume = {1}, number = {125}, pages = {437-448}, abstract = {In this work new methodologies are analyzed in order to solve simulation problems of desalination processes. The basic targets are two: on one hand, reduce the computation effort (time consumption) and on the other hand, achieve high flexibility to solve design and optimization problems, and to handle different structural configurations of the process. It is shown that it is possible to reduce the time of computation n-1 times choosing appropriately the tear set. It is also shown that with a new methodology it is possible to reduce again this time drastically. In fact, it is possible to reduce the number of tear streams from n to one. Obviously, this is a more important result according to the value of n. Although the MSF system is used as example, these conclusions are valid for any multi-stage desalination system.}, note = {cited By 0}, keywords = {}, pubstate = {published}, tppubtype = {conference} } In this work new methodologies are analyzed in order to solve simulation problems of desalination processes. The basic targets are two: on one hand, reduce the computation effort (time consumption) and on the other hand, achieve high flexibility to solve design and optimization problems, and to handle different structural configurations of the process. It is shown that it is possible to reduce the time of computation n-1 times choosing appropriately the tear set. It is also shown that with a new methodology it is possible to reduce again this time drastically. In fact, it is possible to reduce the number of tear streams from n to one. Obviously, this is a more important result according to the value of n. Although the MSF system is used as example, these conclusions are valid for any multi-stage desalination system. |

## 1990 |

E.C. Martínez, L.J. Beltramini Lumping upon time-scales: Modeling upon topological factors (Artículo de revista) Chemical Engineering Science, 45 (8), pp. 2103-2108, 1990, (cited By 2). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Martinez19902103, title = {Lumping upon time-scales: Modeling upon topological factors}, author = { E.C. Martínez and L.J. Beltramini}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0025631320&partnerID=40&md5=f39f5b318b028829811221d7fdabb395}, doi = {10.1016/0009-2509(90)80083-Q}, year = {1990}, date = {1990-01-01}, journal = {Chemical Engineering Science}, volume = {45}, number = {8}, pages = {2103-2108}, abstract = {Many properties of reaction mechanisms favoring chemical lumping can be easily deduced from certain patterns of their topology. This is particularly the case when lumping is practised upon the time-scales of reaction dynamics. This paper develops an approach to lumping based on the presence of sparse and dense connections between species through elementary reactions. A lumped model of the mechanism is constructed based on the fundamental relationship between the notion of weak boundaries induced by topological factors and the presence of multitime-scales. Weakness of pseudospecies boundaries are analytically expressed by means of a singular perturbation parameter. Lumping upon topological factors are then formalized by the singular perturbation method. According to the actual strength of pseudospecies boundaries the lumped model can be iteratively improved. © 1990.}, note = {cited By 2}, keywords = {}, pubstate = {published}, tppubtype = {article} } Many properties of reaction mechanisms favoring chemical lumping can be easily deduced from certain patterns of their topology. This is particularly the case when lumping is practised upon the time-scales of reaction dynamics. This paper develops an approach to lumping based on the presence of sparse and dense connections between species through elementary reactions. A lumped model of the mechanism is constructed based on the fundamental relationship between the notion of weak boundaries induced by topological factors and the presence of multitime-scales. Weakness of pseudospecies boundaries are analytically expressed by means of a singular perturbation parameter. Lumping upon topological factors are then formalized by the singular perturbation method. According to the actual strength of pseudospecies boundaries the lumped model can be iteratively improved. © 1990. |

J. Cerdá, M.R. Galli, N. Camussi, M.A. Isla Synthesis of flexible heat exchanger networks-I. Convex networks (Artículo de revista) Computers and Chemical Engineering, 14 (2), pp. 197-211, 1990, (cited By 21). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Cerdá1990197, title = {Synthesis of flexible heat exchanger networks-I. Convex networks}, author = { J. Cerdá and M.R. Galli and N. Camussi and M.A. Isla}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0025388133&partnerID=40&md5=5503840eee047c27699d261709e33de5}, doi = {10.1016/0098-1354(90)87078-4}, year = {1990}, date = {1990-01-01}, journal = {Computers and Chemical Engineering}, volume = {14}, number = {2}, pages = {197-211}, abstract = {A new methodology for the optimal synthesis of structurally flexible heat exchanger networks is presented. Since the stream supply temperatures are specified by ranges rather than fixed values, the sought network design must be able to reach the target temperatures for any realization of the uncertain parameters. Moreover, it should always require a minimum utility consumption. To this end, an optimal heat recovery strategy is derived by using the notion of transient and permanent process streams. Based on it, a novel version of the heat cascade which assumes a continuous pinch behavior is developed to determine: (i) the heat recovery targets to be achieved by the network; and (ii) the dominant pinch temperatures constraining the heat exchanges and defining the problem subnetworks. They constitute the building blocks of an MILP mathematical formulation through which a structurally flexible network featuring the least number of units is found. Unlike prior attempts, a feasibility condition handled as a model restriction eliminates the need for flexibility tests. A couple of examples involving convex pinch domains have been successfully solved in a short computer time. This shows a slight increase with the number of uncertainties. The method has been extended to the synthesis of nonconvex networks in Part II. © 1990.}, note = {cited By 21}, keywords = {}, pubstate = {published}, tppubtype = {article} } A new methodology for the optimal synthesis of structurally flexible heat exchanger networks is presented. Since the stream supply temperatures are specified by ranges rather than fixed values, the sought network design must be able to reach the target temperatures for any realization of the uncertain parameters. Moreover, it should always require a minimum utility consumption. To this end, an optimal heat recovery strategy is derived by using the notion of transient and permanent process streams. Based on it, a novel version of the heat cascade which assumes a continuous pinch behavior is developed to determine: (i) the heat recovery targets to be achieved by the network; and (ii) the dominant pinch temperatures constraining the heat exchanges and defining the problem subnetworks. They constitute the building blocks of an MILP mathematical formulation through which a structurally flexible network featuring the least number of units is found. Unlike prior attempts, a feasibility condition handled as a model restriction eliminates the need for flexibility tests. A couple of examples involving convex pinch domains have been successfully solved in a short computer time. This shows a slight increase with the number of uncertainties. The method has been extended to the synthesis of nonconvex networks in Part II. © 1990. |

J. Cerdá, M.R. Galli Synthesis of flexible heat exchanger networks-II. Nonconvex networks with large temperature variations (Artículo de revista) Computers and Chemical Engineering, 14 (2), pp. 213-225, 1990, (cited By 15). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Cerdá1990213, title = {Synthesis of flexible heat exchanger networks-II. Nonconvex networks with large temperature variations}, author = { J. Cerdá and M.R. Galli}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0025386665&partnerID=40&md5=1e302c7db8910abef0883ab6ccd5634a}, doi = {10.1016/0098-1354(90)87079-5}, year = {1990}, date = {1990-01-01}, journal = {Computers and Chemical Engineering}, volume = {14}, number = {2}, pages = {213-225}, abstract = {New features have been incorporated to the systematic algorithmic approach presented in Part I to make it capable of solving nonconvex HENS problems with large temperature disturbances. They permit detection of pinch-jumps and evaluate the intermediate temperatures at which the discontinuities arise. At pinch-jump conditions, a pair of simultaneous pinch temperatures are observed, requiring further units to reach maximum energy recovery. Additional partitioning of the process streams at such temperatures make it possible to reach the energy target everywhere. Application of the method to the solution of several nonconvex examples yields networks comprising the fewest number of units to always minimize the utility usage. Because they are built-in, feasibility tests are not required. The efficiency of the method remains remarkable even for a seven-stream problem. © 1990.}, note = {cited By 15}, keywords = {}, pubstate = {published}, tppubtype = {article} } New features have been incorporated to the systematic algorithmic approach presented in Part I to make it capable of solving nonconvex HENS problems with large temperature disturbances. They permit detection of pinch-jumps and evaluate the intermediate temperatures at which the discontinuities arise. At pinch-jump conditions, a pair of simultaneous pinch temperatures are observed, requiring further units to reach maximum energy recovery. Additional partitioning of the process streams at such temperatures make it possible to reach the energy target everywhere. Application of the method to the solution of several nonconvex examples yields networks comprising the fewest number of units to always minimize the utility usage. Because they are built-in, feasibility tests are not required. The efficiency of the method remains remarkable even for a seven-stream problem. © 1990. |

G. Stephanopoulos, G. Henning, H.P. Leone MODEL.LA. A modeling language for process engineering-II. Multifaceted modeling of processing systems (Artículo de revista) Computers and Chemical Engineering, 14 (8), pp. 847-869, 1990, (cited By 35). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Stephanopoulos1990847, title = {MODEL.LA. A modeling language for process engineering-II. Multifaceted modeling of processing systems}, author = { G. Stephanopoulos and G. Henning and H.P. Leone}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0025466868&partnerID=40&md5=3aee35410a3f7c67b1ccb5829b47dd41}, doi = {10.1016/0098-1354(90)87041-M}, year = {1990}, date = {1990-01-01}, journal = {Computers and Chemical Engineering}, volume = {14}, number = {8}, pages = {847-869}, abstract = {Multifaceted (multiview, multicontext, multilevel) modeling of processing systems is a central requirement for further automation of process engineering tasks. This paper describes how the formal framework of MODEL.LA., established in Part I, is being used to construct multifaceted models of processing systems. More specifically, it shows how MODEL.LA. (a) can access multiple views of a model; (b) generate contextual models; and (c) establish consistency among multiple, concurrent models developed at different levels of abstraction. The procedures carrying out these operations are described and a series of illustrations is used to clarify the various concepts. © 1990.}, note = {cited By 35}, keywords = {}, pubstate = {published}, tppubtype = {article} } Multifaceted (multiview, multicontext, multilevel) modeling of processing systems is a central requirement for further automation of process engineering tasks. This paper describes how the formal framework of MODEL.LA., established in Part I, is being used to construct multifaceted models of processing systems. More specifically, it shows how MODEL.LA. (a) can access multiple views of a model; (b) generate contextual models; and (c) establish consistency among multiple, concurrent models developed at different levels of abstraction. The procedures carrying out these operations are described and a series of illustrations is used to clarify the various concepts. © 1990. |

G. Stephanopoulos, G. Henning, H.P. Leone MODEL.LA. A modeling language for process engineering-I. The formal framework (Artículo de revista) Computers and Chemical Engineering, 14 (8), pp. 813-846, 1990, (cited By 89). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Stephanopoulos1990813, title = {MODEL.LA. A modeling language for process engineering-I. The formal framework}, author = { G. Stephanopoulos and G. Henning and H.P. Leone}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0025467263&partnerID=40&md5=83aaf099f506afb11bd3853ca0c49572}, doi = {10.1016/0098-1354(90)87040-V}, year = {1990}, date = {1990-01-01}, journal = {Computers and Chemical Engineering}, volume = {14}, number = {8}, pages = {813-846}, abstract = {A modeling language (MODEL.LA.) has been constructed for the interactive or automatic definition of models for processing systems. It is based on six modeling elements and 11 semantic relationships obeying basic axioms of transitivity, monotonicity, commutativity and merging. Its syntax can be described by an extended BNF (Backus-Naur Form). The structure of process models is depicted by specific digraphs, which are symbolically constructed by algorithmic procedures driven by the context of the modeling activity. MODEL.LA. can generate models of processing systems: (a) at various levels of abstraction; (b) capturing qualitative, semiquantitative and quantitative knowledge; (c) with complete documentation of the modeling context (assumptions, simplifications, process engineering task). Its object-oriented modularity makes it extensible and easily maintainable. Although a large part of MODEL.LA. is domain-independent, its vocabulary and syntax is specific to process engineering activities such as: process development, design, control and operations. A language for modeling processing systems, called MODEL.LA., has been presented. Realizing the limitations of the previous procedural attempts, it is based on an object-oriented, declarative approach. The language has been designed to be capable of: (i) expressing all points of interest assumed to be needed in modeling processing systems; (ii) representing processing systems at any level of detail; (iii) generating automatically the set of basic mathematical relationships that are describing the model components; and (iv) offering explicit documentation of all the assumptions that give rise to a particular model. It can be viewed as a very high-level special-purpose language, that moves the user several levels away from the inherent programming language (e.g. LISP, as in this case, Pascal or C). MODEL.LA. complies with all the requirements that were proposed for its design. Its basic strengths are its modularity and its inherent capability of controlling complexity by breaking down complex systems into smaller, less complex pieces. In fact, the specification of a model-class involves the subsequent specification and characterization of all its components. This idea is recursively applied throughout the definition process. Thus, it is very similar to what we usually do when we describe processing systems in natural languages. Another important feature of this language is its extensibility. At a very simple level, the ability to characterize a processing system can be extended by incorporating a richer terminal vocabulary. Also, its modularity makes possible the incorporation of new blocks in the definition of a class; blocks that may describe other aspects, that presently are not considered. If the incorporation of new modeling points of view requires the definition of new classes of modeling elements, it can be done in a straightforward manner. © 1990.}, note = {cited By 89}, keywords = {}, pubstate = {published}, tppubtype = {article} } A modeling language (MODEL.LA.) has been constructed for the interactive or automatic definition of models for processing systems. It is based on six modeling elements and 11 semantic relationships obeying basic axioms of transitivity, monotonicity, commutativity and merging. Its syntax can be described by an extended BNF (Backus-Naur Form). The structure of process models is depicted by specific digraphs, which are symbolically constructed by algorithmic procedures driven by the context of the modeling activity. MODEL.LA. can generate models of processing systems: (a) at various levels of abstraction; (b) capturing qualitative, semiquantitative and quantitative knowledge; (c) with complete documentation of the modeling context (assumptions, simplifications, process engineering task). Its object-oriented modularity makes it extensible and easily maintainable. Although a large part of MODEL.LA. is domain-independent, its vocabulary and syntax is specific to process engineering activities such as: process development, design, control and operations. A language for modeling processing systems, called MODEL.LA., has been presented. Realizing the limitations of the previous procedural attempts, it is based on an object-oriented, declarative approach. The language has been designed to be capable of: (i) expressing all points of interest assumed to be needed in modeling processing systems; (ii) representing processing systems at any level of detail; (iii) generating automatically the set of basic mathematical relationships that are describing the model components; and (iv) offering explicit documentation of all the assumptions that give rise to a particular model. It can be viewed as a very high-level special-purpose language, that moves the user several levels away from the inherent programming language (e.g. LISP, as in this case, Pascal or C). MODEL.LA. complies with all the requirements that were proposed for its design. Its basic strengths are its modularity and its inherent capability of controlling complexity by breaking down complex systems into smaller, less complex pieces. In fact, the specification of a model-class involves the subsequent specification and characterization of all its components. This idea is recursively applied throughout the definition process. Thus, it is very similar to what we usually do when we describe processing systems in natural languages. Another important feature of this language is its extensibility. At a very simple level, the ability to characterize a processing system can be extended by incorporating a richer terminal vocabulary. Also, its modularity makes possible the incorporation of new blocks in the definition of a class; blocks that may describe other aspects, that presently are not considered. If the incorporation of new modeling points of view requires the definition of new classes of modeling elements, it can be done in a straightforward manner. © 1990. |

E.O. Pavani, P.A. Aguirre, H.A. Irazoqui Optimal synthesis of heat-and-power systems: the operating line method (Artículo de revista) International Journal of Heat and Mass Transfer, 33 (12), pp. 2683-2699, 1990, (cited By 4). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Pavani19902683, title = {Optimal synthesis of heat-and-power systems: the operating line method}, author = { E.O. Pavani and P.A. Aguirre and H.A. Irazoqui}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0025591882&partnerID=40&md5=beea5e2f9cf0ad4bc86fbb0f3cff68db}, doi = {10.1016/0017-9310(90)90204-8}, year = {1990}, date = {1990-01-01}, journal = {International Journal of Heat and Mass Transfer}, volume = {33}, number = {12}, pages = {2683-2699}, abstract = {The physical and mathematical models on which the operating line method (OLM) (H. A. Irazoqui, Chem. Engng Sci. 41, 1243-1255 (1986); P. A. Aguirre, E. O. Pavani and H. A. Irazoqui, Chem. Engng Sci. 44, 803-816 (1989)) for the optimal synthesis of heat-and-power systems is built, are discussed in depth. These models include the heat exchange 'modes' allowed and the general features of the type of solution sought in order to reach an optimal scheme for the total energy systems in chemical plants. A thorough development of the mathematical technique used to tackle the optimization problem is also made. This development comprises the derivation of the necessary and sufficient conditions for optimality. © 1990.}, note = {cited By 4}, keywords = {}, pubstate = {published}, tppubtype = {article} } The physical and mathematical models on which the operating line method (OLM) (H. A. Irazoqui, Chem. Engng Sci. 41, 1243-1255 (1986); P. A. Aguirre, E. O. Pavani and H. A. Irazoqui, Chem. Engng Sci. 44, 803-816 (1989)) for the optimal synthesis of heat-and-power systems is built, are discussed in depth. These models include the heat exchange 'modes' allowed and the general features of the type of solution sought in order to reach an optimal scheme for the total energy systems in chemical plants. A thorough development of the mathematical technique used to tackle the optimization problem is also made. This development comprises the derivation of the necessary and sufficient conditions for optimality. © 1990. |

P.A. Aguirre, E.O. Pavani, H.A. Irazoqui Optimal synthesis of heat-and-power systems with multiple steam levels (Artículo de revista) Chemical Engineering Science, 45 (1), pp. 117-129, 1990, (cited By 1). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Aguirre1990117, title = {Optimal synthesis of heat-and-power systems with multiple steam levels}, author = { P.A. Aguirre and E.O. Pavani and H.A. Irazoqui}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0025567642&partnerID=40&md5=67faf63eb17e099e5699116f2030d54a}, doi = {10.1016/0009-2509(90)87086-8}, year = {1990}, date = {1990-01-01}, journal = {Chemical Engineering Science}, volume = {45}, number = {1}, pages = {117-129}, abstract = {In this paper, the extension of the operating line method (Irazoqui, 1986, Chem. Engng Sci. 41, 5) for the optimal synthesis of heat-and-power systems with dominant power load to the more general case of multiple steam levels is made. The thermodynamic meaning of the optimality region, obtained as a necessary condition for optimality, is also uncovered. An interesting feature of the optimal solution for the integration problem with multiple steam levels is that integration gaps arise. The optimal solution is compared to other solutions which appear as natural alternatives to it on the basis of the same value of the total area of heat exchangers and the same total power output. They all show lower values of their efficiencies to generate shaft power. © 1989.}, note = {cited By 1}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this paper, the extension of the operating line method (Irazoqui, 1986, Chem. Engng Sci. 41, 5) for the optimal synthesis of heat-and-power systems with dominant power load to the more general case of multiple steam levels is made. The thermodynamic meaning of the optimality region, obtained as a necessary condition for optimality, is also uncovered. An interesting feature of the optimal solution for the integration problem with multiple steam levels is that integration gaps arise. The optimal solution is compared to other solutions which appear as natural alternatives to it on the basis of the same value of the total area of heat exchangers and the same total power output. They all show lower values of their efficiencies to generate shaft power. © 1989. |

## 1989 |

E.C. Martínez Hidden time-scales in nonlinear systems (Artículo de revista) Mathematical and Computer Modelling, 12 (6), pp. 659-666, 1989, (cited By 1). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Martínez1989659, title = {Hidden time-scales in nonlinear systems}, author = { E.C. Martínez}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0024913137&partnerID=40&md5=3446f1ba4ad32eaefd2fe46aebb980c9}, doi = {10.1016/0895-7177(89)90351-8}, year = {1989}, date = {1989-01-01}, journal = {Mathematical and Computer Modelling}, volume = {12}, number = {6}, pages = {659-666}, abstract = {Many physical and man-made systems have hidden time-scales characterized by two singular perturbation parameters. This form often arises for nonlinear dynamic networks due to the presence of small and large storage elements, such as capacitors, material and energy reservoirs, masses etc., interconnected with small and large resistors, weak and strong springs, admittances etc. In this paper we emphasize the physical situation by examples and also present a manifold-based analysis which permits the construction of a nonsingular transformation for expressing the original problem in an explicit form. The interpretation of these hidden time-scales is based on aggregate conservation and hierarchical equilibrium properties, a refinement of those presented previously. © 1989.}, note = {cited By 1}, keywords = {}, pubstate = {published}, tppubtype = {article} } Many physical and man-made systems have hidden time-scales characterized by two singular perturbation parameters. This form often arises for nonlinear dynamic networks due to the presence of small and large storage elements, such as capacitors, material and energy reservoirs, masses etc., interconnected with small and large resistors, weak and strong springs, admittances etc. In this paper we emphasize the physical situation by examples and also present a manifold-based analysis which permits the construction of a nonsingular transformation for expressing the original problem in an explicit form. The interpretation of these hidden time-scales is based on aggregate conservation and hierarchical equilibrium properties, a refinement of those presented previously. © 1989. |

O.J. Chiotti, O.A. Iribarren An optimization module for batch distillation with intermediate cuts (Artículo de revista) Computers in Industry, 13 (2), pp. 169-180, 1989, (cited By 3). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Chiotti1989169, title = {An optimization module for batch distillation with intermediate cuts}, author = { O.J. Chiotti and O.A. Iribarren}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0024765365&partnerID=40&md5=f47207d62d2040d255c9244061943052}, doi = {10.1016/0166-3615(89)90047-X}, year = {1989}, date = {1989-01-01}, journal = {Computers in Industry}, volume = {13}, number = {2}, pages = {169-180}, abstract = {An optimization module is presented which approximates the optimal value of the design and operation variables of a batch distillation still. The required computation time is very small compared with any rigorous simulation approach. The module implements the strategy by Chiotti (1989) for developing simplified models to represent the behaviour of batch distillations with intermediate cuts that are recycled for reprocessing. This module is useful for preliminary design and screening of the numerous alternative operation policies which arise in multi-component batch distillations. © 1989.}, note = {cited By 3}, keywords = {}, pubstate = {published}, tppubtype = {article} } An optimization module is presented which approximates the optimal value of the design and operation variables of a batch distillation still. The required computation time is very small compared with any rigorous simulation approach. The module implements the strategy by Chiotti (1989) for developing simplified models to represent the behaviour of batch distillations with intermediate cuts that are recycled for reprocessing. This module is useful for preliminary design and screening of the numerous alternative operation policies which arise in multi-component batch distillations. © 1989. |

O.J. Chiotti, N. Scenna A batch distillation module integrated to the process simulator simbad (Artículo de revista) Computers in Industry, 12 (4), pp. 299-306, 1989, (cited By 2). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Chiotti1989299, title = {A batch distillation module integrated to the process simulator simbad}, author = { O.J. Chiotti and N. Scenna}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0024714333&partnerID=40&md5=64df0ef5173bf028edd4b03067ac6c0a}, doi = {10.1016/0166-3615(89)90010-9}, year = {1989}, date = {1989-01-01}, journal = {Computers in Industry}, volume = {12}, number = {4}, pages = {299-306}, abstract = {This paper presents the structure of a dynamic simulation module for batch distillation. For a batch rectification in its simpler version, it consists of an integration module that solves the system of ordinary differential equations describing the reboiler, a steady-state simulation module describing the column, and a physicochemical properties module. The modules interact among each other at each intermediate integration step. The integration module, written in a dynamic simulation language, is the only new one. The main objective of this structure was to obtain a reliable batch simulation package, fully integrated to the already existing modules of the Process Simulator simbad. This makes the structure quite flexible, with the user specifying the operation mode (rectification or stripping), the column solver methodology (Naphtali-Sandholm, Tomich, etc.), the physicochemical properties package (rks, unifac, etc.), besides any other interactive capability already built in the Simulator. For example tray efficiencies in Naphtali-Sandholm may be updated by the hydraulic verification modules, so that its variation with composition can be traced. © 1989.}, note = {cited By 2}, keywords = {}, pubstate = {published}, tppubtype = {article} } This paper presents the structure of a dynamic simulation module for batch distillation. For a batch rectification in its simpler version, it consists of an integration module that solves the system of ordinary differential equations describing the reboiler, a steady-state simulation module describing the column, and a physicochemical properties module. The modules interact among each other at each intermediate integration step. The integration module, written in a dynamic simulation language, is the only new one. The main objective of this structure was to obtain a reliable batch simulation package, fully integrated to the already existing modules of the Process Simulator simbad. This makes the structure quite flexible, with the user specifying the operation mode (rectification or stripping), the column solver methodology (Naphtali-Sandholm, Tomich, etc.), the physicochemical properties package (rks, unifac, etc.), besides any other interactive capability already built in the Simulator. For example tray efficiencies in Naphtali-Sandholm may be updated by the hydraulic verification modules, so that its variation with composition can be traced. © 1989. |

N.J. Scenna, P.A. Aguirre Optimal thermodynamic heat transfer (Artículo de revista) Industrial and Engineering Chemistry Research, 28 (6), pp. 873-875, 1989, (cited By 3). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Scenna1989873, title = {Optimal thermodynamic heat transfer}, author = { N.J. Scenna and P.A. Aguirre}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0024680797&partnerID=40&md5=b6392425458cf9c01bc12ae41b4646d6}, year = {1989}, date = {1989-01-01}, journal = {Industrial and Engineering Chemistry Research}, volume = {28}, number = {6}, pages = {873-875}, abstract = {A set of heuristics are presented which are useful for optimal design of heat-exchange networks and integrated heat and power systems. These heuristics consolidate other approaches reported in the literature in a formalism useful for design purposes.}, note = {cited By 3}, keywords = {}, pubstate = {published}, tppubtype = {article} } A set of heuristics are presented which are useful for optimal design of heat-exchange networks and integrated heat and power systems. These heuristics consolidate other approaches reported in the literature in a formalism useful for design purposes. |

P.A. Aguirre, N.J. Scenna Optimal thermodynamic synthesis of dual-purpose desalination plants (Artículo de revista) Chemical Engineering Science, 44 (2), pp. 283-296, 1989, (cited By 5). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Aguirre1989283, title = {Optimal thermodynamic synthesis of dual-purpose desalination plants}, author = { P.A. Aguirre and N.J. Scenna}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0023701984&partnerID=40&md5=8572d2fb32329d00769c47cda7481627}, doi = {10.1016/0009-2509(89)85065-1}, year = {1989}, date = {1989-01-01}, journal = {Chemical Engineering Science}, volume = {44}, number = {2}, pages = {283-296}, abstract = {A thermodynamic approach to teh synthesis of a dual-purpose desanlination system is developed. In a previous paper (Irazoqui, 1986, Chem. Engng Sci. 41, 1243-1255), it was shown that a minimum for the system entropy generation corresponds, if adequate restrictions were imposed, to an optimum in the thermodynamics performance. In this paper a family of optimal thermodynamic but non-ideal solutions is found by "weighing" the impact of the size of the total heat exchange area on the optimal solution sought. The problem is then solved for each value of the weighing parameter. A non-ideality due to mechanical dissipation is introduced by means of the turbine isoentropic efficiency. Optimal structural and operation variables are obtained, which can be easily shown in a graph. © 1989.}, note = {cited By 5}, keywords = {}, pubstate = {published}, tppubtype = {article} } A thermodynamic approach to teh synthesis of a dual-purpose desanlination system is developed. In a previous paper (Irazoqui, 1986, Chem. Engng Sci. 41, 1243-1255), it was shown that a minimum for the system entropy generation corresponds, if adequate restrictions were imposed, to an optimum in the thermodynamics performance. In this paper a family of optimal thermodynamic but non-ideal solutions is found by "weighing" the impact of the size of the total heat exchange area on the optimal solution sought. The problem is then solved for each value of the weighing parameter. A non-ideality due to mechanical dissipation is introduced by means of the turbine isoentropic efficiency. Optimal structural and operation variables are obtained, which can be easily shown in a graph. © 1989. |

P.A. Aguirre, E.O. Pavani, H.A. Irazoqui Comparative analysis of pinch and operating line methods for heat and power integration (Artículo de revista) Chemical Engineering Science, 44 (4), pp. 803-816, 1989, (cited By 3). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Aguirre1989803, title = {Comparative analysis of pinch and operating line methods for heat and power integration}, author = { P.A. Aguirre and E.O. Pavani and H.A. Irazoqui}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0024927311&partnerID=40&md5=23146ca253d8fbbd607902b3e3cf1f11}, doi = {10.1016/0009-2509(89)85254-6}, year = {1989}, date = {1989-01-01}, journal = {Chemical Engineering Science}, volume = {44}, number = {4}, pages = {803-816}, abstract = {Two methods for approaching the problem of the optimal synthesis of heat-and-power cogeneration systems from a thermodynamic point of view are compared. The first one is the pinch method (Townsend and Linnhoff, 1983,A.I.Ch.E. J. 29, 742-771) which is based on the pinch properties. The second one is the operating line method (Irazoqui, 1986, Chem. Engng Sci. 41, 1243-1255) which considers the heat-and-power cogeneration as a unique, nonseparable problem. Different results for the appropriate placement of power-generating cycles can be derived by applying either method, particularly in the case of a "nose"-shaped grand composite curve. The efficiencies obtained with the operating line method are higher than those calculated with the pinch method, when both are applied to a dominant power load case. © 1989.}, note = {cited By 3}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two methods for approaching the problem of the optimal synthesis of heat-and-power cogeneration systems from a thermodynamic point of view are compared. The first one is the pinch method (Townsend and Linnhoff, 1983,A.I.Ch.E. J. 29, 742-771) which is based on the pinch properties. The second one is the operating line method (Irazoqui, 1986, Chem. Engng Sci. 41, 1243-1255) which considers the heat-and-power cogeneration as a unique, nonseparable problem. Different results for the appropriate placement of power-generating cycles can be derived by applying either method, particularly in the case of a "nose"-shaped grand composite curve. The efficiencies obtained with the operating line method are higher than those calculated with the pinch method, when both are applied to a dominant power load case. © 1989. |

J.M. Montagna, O.A. Iribarren A new strategy for process simulation with the sequential modular approach (Artículo de revista) Computers in Industry, 12 (1), pp. 23-29, 1989, (cited By 1). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Montagna198923, title = {A new strategy for process simulation with the sequential modular approach}, author = { J.M. Montagna and O.A. Iribarren}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0024620168&partnerID=40&md5=6c046c27ef9ccb4eb5cfd393d88abbf9}, doi = {10.1016/0166-3615(89)90028-6}, year = {1989}, date = {1989-01-01}, journal = {Computers in Industry}, volume = {12}, number = {1}, pages = {23-29}, abstract = {The "sequential modular" approach is the most often used approach for process simulation. However, it shows certain pitfalls such as the large computation time required by the resolution and some difficulties to approach design and optimization problems. In order to overcome these difficulties a new resolution strategy has been incorporated to the process simulator simbad. Here, the resolution of modules is not exclusively based on the streams that physically enter it but other stream combinations are considered valid as far as the resolution of the system of equations is feasible. This method has helped solving different examples with a noticeable decrease in the required computation time. © 1989.}, note = {cited By 1}, keywords = {}, pubstate = {published}, tppubtype = {article} } The "sequential modular" approach is the most often used approach for process simulation. However, it shows certain pitfalls such as the large computation time required by the resolution and some difficulties to approach design and optimization problems. In order to overcome these difficulties a new resolution strategy has been incorporated to the process simulator simbad. Here, the resolution of modules is not exclusively based on the streams that physically enter it but other stream combinations are considered valid as far as the resolution of the system of equations is feasible. This method has helped solving different examples with a noticeable decrease in the required computation time. © 1989. |

J.M. Montagna, T. Melli, R. Cerro A strategy for the design and optimization of utilities using a systems simulator (Artículo de revista) Computers in Industry, 12 (2), pp. 153-159, 1989, (cited By 0). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Montagna1989153, title = {A strategy for the design and optimization of utilities using a systems simulator}, author = { J.M. Montagna and T. Melli and R. Cerro}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0024662920&partnerID=40&md5=37f99a641f846ed599d925b94be19193}, doi = {10.1016/0166-3615(89)90057-2}, year = {1989}, date = {1989-01-01}, journal = {Computers in Industry}, volume = {12}, number = {2}, pages = {153-159}, abstract = {A steady-state system simulator has been developed, capable of simulating the performance of a wide variety of systems. One of the most interesting applications of this systems simulator is the analysis of performance of steam and electrical power generating plants when their performance and mode of operation is closely related to the operation of a process plant. An interesting feature of the simulator is the fact that all the information is handled by a Data Base Management System. Another novel feature is the fact that the system modules can be solved for a wide variety of input information. Solving modules for the available input information rather than the customary physical input-output fashion, allows in most cases of interest to solve the network using a resolution sequence without cycles or iterations. The drawback of this approach is the fact that modules are no longer naturally inserted using the output of one module as the input of another. To solve this problem, an ordering algorithm was developed that searches for a cycleless resolution sequence taking into account the different modes of resolution of the modules. © 1989.}, note = {cited By 0}, keywords = {}, pubstate = {published}, tppubtype = {article} } A steady-state system simulator has been developed, capable of simulating the performance of a wide variety of systems. One of the most interesting applications of this systems simulator is the analysis of performance of steam and electrical power generating plants when their performance and mode of operation is closely related to the operation of a process plant. An interesting feature of the simulator is the fact that all the information is handled by a Data Base Management System. Another novel feature is the fact that the system modules can be solved for a wide variety of input information. Solving modules for the available input information rather than the customary physical input-output fashion, allows in most cases of interest to solve the network using a resolution sequence without cycles or iterations. The drawback of this approach is the fact that modules are no longer naturally inserted using the output of one module as the input of another. To solve this problem, an ordering algorithm was developed that searches for a cycleless resolution sequence taking into account the different modes of resolution of the modules. © 1989. |

E.C. Martínez, B. Drozdowicz Multitime-scale approach to real-time simulation of stiff dynamic systems (Artículo de revista) Computers and Chemical Engineering, 13 (7), pp. 767-778, 1989, (cited By 7). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Martinez1989767, title = {Multitime-scale approach to real-time simulation of stiff dynamic systems}, author = { E.C. Martínez and B. Drozdowicz}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0024703981&partnerID=40&md5=5235a78d6ec244aba5a30c83df8e3670}, doi = {10.1016/0098-1354(89)85050-1}, year = {1989}, date = {1989-01-01}, journal = {Computers and Chemical Engineering}, volume = {13}, number = {7}, pages = {767-778}, abstract = {Real-time simulation of stiff dynamic systems plays an important role in many areas of chemical process engineering. Notwithstanding the capabilities of well-known available methods, their implementations in a real-time environment do not seem very promising. To cope with these issues, we use a time-scale decomposition based on the singular perturbation method. On this basis, we elaborate on a class of multirate integration algorithms for approximate simulation of stiff-IVPs. The most attractive aspect of the new procedure is that explicit numerical methods can be used for integrating each one of the subsystems created by time-scale modeling. This is a very appealing feature in real-time programming, where excessive computing time would endanger the validity of the simulation. Implementational details on a real-time training simulator are also discussed. © 1989.}, note = {cited By 7}, keywords = {}, pubstate = {published}, tppubtype = {article} } Real-time simulation of stiff dynamic systems plays an important role in many areas of chemical process engineering. Notwithstanding the capabilities of well-known available methods, their implementations in a real-time environment do not seem very promising. To cope with these issues, we use a time-scale decomposition based on the singular perturbation method. On this basis, we elaborate on a class of multirate integration algorithms for approximate simulation of stiff-IVPs. The most attractive aspect of the new procedure is that explicit numerical methods can be used for integrating each one of the subsystems created by time-scale modeling. This is a very appealing feature in real-time programming, where excessive computing time would endanger the validity of the simulation. Implementational details on a real-time training simulator are also discussed. © 1989. |

## 1988 |

H.P. Leone, N. Scenna, A.R. Vecchietti An iso-propanol distillery revamping using a simbad simulator (Artículo de revista) Computers and Chemical Engineering, 12 (8), pp. 807-819, 1988, (cited By 1). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Leone1988807, title = {An iso-propanol distillery revamping using a simbad simulator}, author = { H.P. Leone and N. Scenna and A.R. Vecchietti}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0013763810&partnerID=40&md5=83856e11ceca73cf56ba7a31c3fea475}, doi = {10.1016/0098-1354(88)80019-X}, year = {1988}, date = {1988-01-01}, journal = {Computers and Chemical Engineering}, volume = {12}, number = {8}, pages = {807-819}, abstract = {A distillation train of pure iso-propanol (99.99%) has been studied to determine new operating conditions, in order to attain an increase in throughput without changes in geometrical parameters. A methodology to obtain the operating pressure for the new production rate is analyzed. The Kister and Doig (1977, 1979) criterion (feed capacity vs operating pressure relationship) has been shown to be a good approximation to the experimental and computational column behavior, though the same authors do not assert its validity when it is applied to mixtures like the one analyzed in this work. A design integrated system mounted on a data base management system (DBMS) is used for the computational analysis. This analysis was done with computer-aided plant design (CAD) software integrated to a DBMS. The CAD software consists of a steady-state process simulator (SSPS), a tray hydraulic design and verification program (HDV) and a physicochemical property estimation system (PPS). SSPS and HDV interact with PPS by requesting estimations of thermodynamic and transport properties. The paper highlights the power of data base integrated software when it is applied to process analysis. Several authors have focused on the stability of the algorithms used for the simulation of azeotropic columns. The Naphtali and Sandholm (1971) convergence method applied to an azeotropic tower coupled with a liquid-liquid separator has proved to be an interesting methodology without convergence troubles in the wide range that was analyzed. Our simulation experience to overcome this kind of drawbacks is described. © 1988.}, note = {cited By 1}, keywords = {}, pubstate = {published}, tppubtype = {article} } A distillation train of pure iso-propanol (99.99%) has been studied to determine new operating conditions, in order to attain an increase in throughput without changes in geometrical parameters. A methodology to obtain the operating pressure for the new production rate is analyzed. The Kister and Doig (1977, 1979) criterion (feed capacity vs operating pressure relationship) has been shown to be a good approximation to the experimental and computational column behavior, though the same authors do not assert its validity when it is applied to mixtures like the one analyzed in this work. A design integrated system mounted on a data base management system (DBMS) is used for the computational analysis. This analysis was done with computer-aided plant design (CAD) software integrated to a DBMS. The CAD software consists of a steady-state process simulator (SSPS), a tray hydraulic design and verification program (HDV) and a physicochemical property estimation system (PPS). SSPS and HDV interact with PPS by requesting estimations of thermodynamic and transport properties. The paper highlights the power of data base integrated software when it is applied to process analysis. Several authors have focused on the stability of the algorithms used for the simulation of azeotropic columns. The Naphtali and Sandholm (1971) convergence method applied to an azeotropic tower coupled with a liquid-liquid separator has proved to be an interesting methodology without convergence troubles in the wide range that was analyzed. Our simulation experience to overcome this kind of drawbacks is described. © 1988. |

J.M. Montagna, O.A. Iribarren Optimal resolution sequence of problems modeled by directed graphs (Artículo de revista) Mathematical and Computer Modelling, 10 (7), pp. 515-521, 1988, (cited By 0). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Montagna1988515, title = {Optimal resolution sequence of problems modeled by directed graphs}, author = { J.M. Montagna and O.A. Iribarren}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-45549114590&partnerID=40&md5=80e69c1a480527d93241f2fa5ff2f578}, doi = {10.1016/0895-7177(88)90080-5}, year = {1988}, date = {1988-01-01}, journal = {Mathematical and Computer Modelling}, volume = {10}, number = {7}, pages = {515-521}, abstract = {Several sciences (engineering, economics etc.) handle problems modeled by directed graphs. The nodes are the sites where the information, transmitted following the arcs, is modified. A formulation to obtain the optimum execution sequence for solving the problem is presented. The constraints requiring that arcs have the same direction as in the actual problem are removed, and the optimal directions for the resolution are the result of an integer linear optimization program. The optimality criterion is to minimize the computer time for the resolution, reducing the iteration levels (inside modules, on recycles, due to optimization loops etc.) of the problem. © 1988.}, note = {cited By 0}, keywords = {}, pubstate = {published}, tppubtype = {article} } Several sciences (engineering, economics etc.) handle problems modeled by directed graphs. The nodes are the sites where the information, transmitted following the arcs, is modified. A formulation to obtain the optimum execution sequence for solving the problem is presented. The constraints requiring that arcs have the same direction as in the actual problem are removed, and the optimal directions for the resolution are the result of an integer linear optimization program. The optimality criterion is to minimize the computer time for the resolution, reducing the iteration levels (inside modules, on recycles, due to optimization loops etc.) of the problem. © 1988. |

J.M. Montagna, O.A. Iribarren Optimal computation sequence in the simulation of chemical plants (Artículo de revista) Computers and Chemical Engineering, 12 (1), pp. 71-79, 1988, (cited By 4). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Montagna198871, title = {Optimal computation sequence in the simulation of chemical plants}, author = { J.M. Montagna and O.A. Iribarren}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0023861205&partnerID=40&md5=40d484c7e2632152e8ab898cc8228d92}, doi = {10.1016/0098-1354(88)85006-3}, year = {1988}, date = {1988-01-01}, journal = {Computers and Chemical Engineering}, volume = {12}, number = {1}, pages = {71-79}, abstract = {A new concept is presented for solving process flowsheeting problems within the sequential modular approach. The solution methodology permits a reduction in the required computation time as a result of the optimal nesting of the iteration loops. The iteration levels that traditionally appear are due to the strict information flow patterns of the sequential modular approach. Differentiating between the material flow in the process and the logic flow in the resolution, the direction of the streams is determined to ease the resolution and to take advantage of available information. © 1988.}, note = {cited By 4}, keywords = {}, pubstate = {published}, tppubtype = {article} } A new concept is presented for solving process flowsheeting problems within the sequential modular approach. The solution methodology permits a reduction in the required computation time as a result of the optimal nesting of the iteration loops. The iteration levels that traditionally appear are due to the strict information flow patterns of the sequential modular approach. Differentiating between the material flow in the process and the logic flow in the resolution, the direction of the streams is determined to ease the resolution and to take advantage of available information. © 1988. |

E.C. Martínez HYBRID CONNECTIONS AND TIME-SCALES IN NON-LINEAR SYSTEMS. (Artículo de revista) International Journal of Systems Science, 19 (8), pp. 1499-1513, 1988, (cited By 0). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Martinez19881499, title = {HYBRID CONNECTIONS AND TIME-SCALES IN NON-LINEAR SYSTEMS.}, author = { E.C. Martínez}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0024065780&partnerID=40&md5=557b5d5211da6ca7c1b473f6633dcde5}, year = {1988}, date = {1988-01-01}, journal = {International Journal of Systems Science}, volume = {19}, number = {8}, pages = {1499-1513}, abstract = {Hidden time-scales arising in hybrid-connected systems are studied by a manifold-based approach. This geometric interpretation of time-scales permits the use of equilibrium and conservation properties to characterize a transformation leading the model to a well-posed form, for which an extensive literature is surveyed. As an illustration we apply a recent stability result. An analytical example is also included to show how to construct aggregate and equilibrium models.}, note = {cited By 0}, keywords = {}, pubstate = {published}, tppubtype = {article} } Hidden time-scales arising in hybrid-connected systems are studied by a manifold-based approach. This geometric interpretation of time-scales permits the use of equilibrium and conservation properties to characterize a transformation leading the model to a well-posed form, for which an extensive literature is surveyed. As an illustration we apply a recent stability result. An analytical example is also included to show how to construct aggregate and equilibrium models. |

B. Drozdowicz, E.C. Martínez Reduced models for separation processes in real-time simulators (Artículo de revista) Computers and Chemical Engineering, 12 (6), pp. 547-560, 1988, (cited By 3). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Drozdowicz1988547, title = {Reduced models for separation processes in real-time simulators}, author = { B. Drozdowicz and E.C. Martínez}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0024027504&partnerID=40&md5=f2d1360f16e9cf8b45479a67ff6c595c}, doi = {10.1016/0098-1354(88)87004-2}, year = {1988}, date = {1988-01-01}, journal = {Computers and Chemical Engineering}, volume = {12}, number = {6}, pages = {547-560}, abstract = {In this work, the real-time dynamic simulation of separation processes is considered, which overcome the inconvenience of the large dimensionality of the mathematical models and takes into consideration of abnormal working conditions. The use of reduced models with an adaptive collocation scheme is suggested. The adaptive collocation scheme is necessary because under failure or abnormal operation, large discrepancies between local conditions at some stages and the overall system may appear. In this case a "perturbation front" moving along the column may be produced during the transient. This behavior may produce a local increase of the steepness in the composition profile. The use of absorption factors is suggested in order to relate the local operative conditions of the column to the local "steepness" of the composition profiles. The proposed procedure has been developed bearing in mind a real-time programming environment. The inclusion of the reduced models in a simulator for operators training is discussed. Different emergency situations of a distillation column are illustrated through an example. © 1988.}, note = {cited By 3}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this work, the real-time dynamic simulation of separation processes is considered, which overcome the inconvenience of the large dimensionality of the mathematical models and takes into consideration of abnormal working conditions. The use of reduced models with an adaptive collocation scheme is suggested. The adaptive collocation scheme is necessary because under failure or abnormal operation, large discrepancies between local conditions at some stages and the overall system may appear. In this case a "perturbation front" moving along the column may be produced during the transient. This behavior may produce a local increase of the steepness in the composition profile. The use of absorption factors is suggested in order to relate the local operative conditions of the column to the local "steepness" of the composition profiles. The proposed procedure has been developed bearing in mind a real-time programming environment. The inclusion of the reduced models in a simulator for operators training is discussed. Different emergency situations of a distillation column are illustrated through an example. © 1988. |

## 1987 |

J.M. Montagna, H.P. Leone, T. Melli, A.R. Vecchietti, R. Cerro SIMBAD: A process simulator linked to a DBMS-I. The executive system (Artículo de revista) Computers and Chemical Engineering, 11 (1), pp. 63-71, 1987, (cited By 5). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Montagna198763, title = {SIMBAD: A process simulator linked to a DBMS-I. The executive system}, author = { J.M. Montagna and H.P. Leone and T. Melli and A.R. Vecchietti and R. Cerro}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0023271561&partnerID=40&md5=3bfbcbb1c7b8556f0fe31da8b0addb04}, doi = {10.1016/0098-1354(87)80006-6}, year = {1987}, date = {1987-01-01}, journal = {Computers and Chemical Engineering}, volume = {11}, number = {1}, pages = {63-71}, abstract = {The data-handling capabilities of a commercial data base management system (DBMS) are used to control the information flow in a sequential modular steady-state process simulator. Thus, a new structure for the execution of this type of simulators is presented, in which executable program using a rigid agenda from a command file are called sequentially to reduce the amount of main memory occupied during the execution. All the executable programs, representing the basic simulation modules, recover information from the data base and return the new information generated through a common procedure. © 1985.}, note = {cited By 5}, keywords = {}, pubstate = {published}, tppubtype = {article} } The data-handling capabilities of a commercial data base management system (DBMS) are used to control the information flow in a sequential modular steady-state process simulator. Thus, a new structure for the execution of this type of simulators is presented, in which executable program using a rigid agenda from a command file are called sequentially to reduce the amount of main memory occupied during the execution. All the executable programs, representing the basic simulation modules, recover information from the data base and return the new information generated through a common procedure. © 1985. |

T. Melli, H.P. Leone, J.M. Montagna, O. Ortiz, N. Scenna, A.R. Vecchietti, R. Cerro A steady state process simulator with a dbms (simbad) (Artículo de revista) Computers in Industry, 8 (1), pp. 13-35, 1987, (cited By 5). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Melli198713, title = {A steady state process simulator with a dbms (simbad)}, author = { T. Melli and H.P. Leone and J.M. Montagna and O. Ortiz and N. Scenna and A.R. Vecchietti and R. Cerro}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0023295779&partnerID=40&md5=5ff4e5b98e8a0a3b155a37c7ee8ca233}, doi = {10.1016/0166-3615(87)90017-0}, year = {1987}, date = {1987-01-01}, journal = {Computers in Industry}, volume = {8}, number = {1}, pages = {13-35}, abstract = {The information handling capability of Data Base Management Programs, together with heat and mass balances programs, has given rise to a new generation of chemical processes simulators. This new generation combines versatility and reliability in the handling of information, with software versions which are both powerful and precise. SIMBAD/INGAR is such a kind of program, highly versatile and able to handle an unlimited variety of chemical components. © 1987.}, note = {cited By 5}, keywords = {}, pubstate = {published}, tppubtype = {article} } The information handling capability of Data Base Management Programs, together with heat and mass balances programs, has given rise to a new generation of chemical processes simulators. This new generation combines versatility and reliability in the handling of information, with software versions which are both powerful and precise. SIMBAD/INGAR is such a kind of program, highly versatile and able to handle an unlimited variety of chemical components. © 1987. |

H.P. Leone, T. Melli, J.M. Montagna, A.R. Vecchietti, R.L. Cerro SIMBAD: A process simulator linked to a DBMS-III. The physicochemical properties package (Artículo de revista) Computers and Chemical Engineering, 11 (3), pp. 217-226, 1987, (cited By 4). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Leone1987217, title = {SIMBAD: A process simulator linked to a DBMS-III. The physicochemical properties package}, author = { H.P. Leone and T. Melli and J.M. Montagna and A.R. Vecchietti and R.L. Cerro}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0023172911&partnerID=40&md5=ab84f364e5b72bcde7399edd295152f1}, doi = {10.1016/0098-1354(87)85003-2}, year = {1987}, date = {1987-01-01}, journal = {Computers and Chemical Engineering}, volume = {11}, number = {3}, pages = {217-226}, abstract = {A system to predict physicochemical and transport properties for a steady state process simulator is presented. The data handling capabilities of the Physicochemical Properties Package are managed by a Data Base Management System. The structure of the physicochemical package is such that it allows access from the simulator as well as from external users without the need to compile and link the particular programs. This is the case of programs for Process Synthesis, Optimization, Equipment Design or simply interactive programs for the prediction of process stream properties. Thus, flexibility of operation is achieved as well as an efficient use of memory. Scope-Easy and prompt access of physicochemical properties has been one of the main problems associated with the design of chemical processes and the evaluation of process equipment performance. Large amounts of research have been done into the experimental determination of the physicochemical properties, as well as in the development of accurate and reliable correlations. The last 2 decades have seen the emergence of large and powerful data bases dedicated to providing a comprehensive treatment of components and mixtures properties as well as more modest, simple and fast systems associated with process simulators. The later type accumulates pure component data (critical constants, normal points, binary interaction parameters, etc.) in order to be able to predict single component and mixed stream properties. The emphasis in the design of the physicochemical package associated with steady state process simulators is efficient computation, flexibility and easiness to update data. Thus, the structure of memory used is of paramount importance in the overall performance of the simulator. Conclusions and Significance-The Physicochemical Properties Package presented here is based on a collection of executable versions of traditional property estimation programs. The system is supported by a physicochemical data base whose structure is defined and maintained by a data base management system of the network type. The structural flexibility achieved by this configuration assures a continuous updating of components as well as of the methods to be used for property estimation. © 1987.}, note = {cited By 4}, keywords = {}, pubstate = {published}, tppubtype = {article} } A system to predict physicochemical and transport properties for a steady state process simulator is presented. The data handling capabilities of the Physicochemical Properties Package are managed by a Data Base Management System. The structure of the physicochemical package is such that it allows access from the simulator as well as from external users without the need to compile and link the particular programs. This is the case of programs for Process Synthesis, Optimization, Equipment Design or simply interactive programs for the prediction of process stream properties. Thus, flexibility of operation is achieved as well as an efficient use of memory. Scope-Easy and prompt access of physicochemical properties has been one of the main problems associated with the design of chemical processes and the evaluation of process equipment performance. Large amounts of research have been done into the experimental determination of the physicochemical properties, as well as in the development of accurate and reliable correlations. The last 2 decades have seen the emergence of large and powerful data bases dedicated to providing a comprehensive treatment of components and mixtures properties as well as more modest, simple and fast systems associated with process simulators. The later type accumulates pure component data (critical constants, normal points, binary interaction parameters, etc.) in order to be able to predict single component and mixed stream properties. The emphasis in the design of the physicochemical package associated with steady state process simulators is efficient computation, flexibility and easiness to update data. Thus, the structure of memory used is of paramount importance in the overall performance of the simulator. Conclusions and Significance-The Physicochemical Properties Package presented here is based on a collection of executable versions of traditional property estimation programs. The system is supported by a physicochemical data base whose structure is defined and maintained by a data base management system of the network type. The structural flexibility achieved by this configuration assures a continuous updating of components as well as of the methods to be used for property estimation. © 1987. |

A.R. Vecchietti, H.P. Leone, T. Melli, J.M. Montagna, R. Cerro Simbad: a process simulator linked to a DBMS-II. the structure of memory (Artículo de revista) Computers and Chemical Engineering, 11 (5), pp. 519-525, 1987, (cited By 2). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Vecchietti1987519, title = {Simbad: a process simulator linked to a DBMS-II. the structure of memory}, author = { A.R. Vecchietti and H.P. Leone and T. Melli and J.M. Montagna and R. Cerro}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0023565803&partnerID=40&md5=c3fb5f041e312558ac450a9c50953a11}, doi = {10.1016/0098-1354(87)80026-1}, year = {1987}, date = {1987-01-01}, journal = {Computers and Chemical Engineering}, volume = {11}, number = {5}, pages = {519-525}, abstract = {A network type Data Base Management System is used to support the data structure of a modular-sequential, steady state process simulator. The DBMS of a standard CODASYL type is based on the definition of records and the set relationships between an owner and a member record. The structure defined, or SCHEMA, responds to the way data is stored and used during the simultations in order to minimize access time, while maintaining flexibility. An example is developed to illustrate the way data is linked for a particular process application. © 1987.}, note = {cited By 2}, keywords = {}, pubstate = {published}, tppubtype = {article} } A network type Data Base Management System is used to support the data structure of a modular-sequential, steady state process simulator. The DBMS of a standard CODASYL type is based on the definition of records and the set relationships between an owner and a member record. The structure defined, or SCHEMA, responds to the way data is stored and used during the simultations in order to minimize access time, while maintaining flexibility. An example is developed to illustrate the way data is linked for a particular process application. © 1987. |

## 1985 |

S. Swami, O.A. Iribarren, M.F. Malone OPTIMAL CYCLE TIMES AND SCHEDULING OF BATCH CHEMICAL PROCESSES. (Conferencia) 1985, (cited By 0). (Resumen | Enlaces | BibTeX | Etiquetas: ) @conference{Swami198561, title = {OPTIMAL CYCLE TIMES AND SCHEDULING OF BATCH CHEMICAL PROCESSES.}, author = { S. Swami and O.A. Iribarren and M.F. Malone}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0022267051&partnerID=40&md5=6845119656110cca0fc932e000e8de3b}, year = {1985}, date = {1985-01-01}, journal = {Proceedings of the Annual Control Engineering Conference}, pages = {61-68}, abstract = {At the initial design stage, the structure of the flowsheet, the stream flows and compositions, and the optimal range of operation for a chemical process are largely unknown. The work described here is focused toward the selection of the optimal structure and flows which often dominate the economic performance of the process. The multipurpose plant produces two or more products at a time; the number of these products is often much larger than in the multiproduct plant and the market for each may be more uncertain. The discussion here is in the context of the first and second of these categories so that the production rates are considered reasonably well-known and the production schedule will occupy all of the available hours per year.}, note = {cited By 0}, keywords = {}, pubstate = {published}, tppubtype = {conference} } At the initial design stage, the structure of the flowsheet, the stream flows and compositions, and the optimal range of operation for a chemical process are largely unknown. The work described here is focused toward the selection of the optimal structure and flows which often dominate the economic performance of the process. The multipurpose plant produces two or more products at a time; the number of these products is often much larger than in the multiproduct plant and the market for each may be more uncertain. The discussion here is in the context of the first and second of these categories so that the production rates are considered reasonably well-known and the production schedule will occupy all of the available hours per year. |

M.F. Malone, O.A. Iribarren SYSTEMATIC PROCEDURE FOR BATCH PROCESS SYNTHESIS. (Conferencia) 1985, (cited By 0). (Resumen | Enlaces | BibTeX | Etiquetas: ) @conference{Malone1985, title = {SYSTEMATIC PROCEDURE FOR BATCH PROCESS SYNTHESIS.}, author = { M.F. Malone and O.A. Iribarren}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0022245483&partnerID=40&md5=cfcf77f918103d2b9574b30c84bf7cef}, year = {1985}, date = {1985-01-01}, journal = {Annual Meeting - American Institute of Chemical Engineers}, abstract = {A procedure for screening flowsheet alternatives and establishing targets for batch processing, primarily for single product plants, is described. The procedure begins with the best continuous flowsheet. Batch flowsheets are generated by replacing continuous units by batch equipment and also by merging tasks into a single batch unit. The procedure points out the role of economy of scale in the economics of the process and the decision between a batch and a continuous process and also among all of the batch flowsheets that can be made. The manufacture of butadiene sulfone from butadiene and sulfur dioxide is discussed as an example.}, note = {cited By 0}, keywords = {}, pubstate = {published}, tppubtype = {conference} } A procedure for screening flowsheet alternatives and establishing targets for batch processing, primarily for single product plants, is described. The procedure begins with the best continuous flowsheet. Batch flowsheets are generated by replacing continuous units by batch equipment and also by merging tasks into a single batch unit. The procedure points out the role of economy of scale in the economics of the process and the decision between a batch and a continuous process and also among all of the batch flowsheets that can be made. The manufacture of butadiene sulfone from butadiene and sulfur dioxide is discussed as an example. |

A. Meystel, E.C. Martínez, C. Isik INTELLIGENT MODULE FOR A MOBILE AUTONOMOUS SYSTEM: STRUCTURE OF LINGUISTICAL CONTROLLER. (Conferencia) 1985, (cited By 0). (Resumen | Enlaces | BibTeX | Etiquetas: ) @conference{Meystel1985154, title = {INTELLIGENT MODULE FOR A MOBILE AUTONOMOUS SYSTEM: STRUCTURE OF LINGUISTICAL CONTROLLER.}, author = { A. Meystel and E.C. Martínez and C. Isik}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0021788237&partnerID=40&md5=4caca392f92e275382b0222e20aaeb94}, year = {1985}, date = {1985-01-01}, journal = {Proceedings of the Hawaii International Conference on System Science}, pages = {154-167}, abstract = {A linguistical structure for a hierarchical intelligent system is described. Languages for a higher and lower level controller are formed in accordance with the knowledge resolution. Interactions between the rule based levels of control are explored.}, note = {cited By 0}, keywords = {}, pubstate = {published}, tppubtype = {conference} } A linguistical structure for a hierarchical intelligent system is described. Languages for a higher and lower level controller are formed in accordance with the knowledge resolution. Interactions between the rule based levels of control are explored. |

## 1984 |

E.C. Martínez, J.M. Tarela, C.D. Prada ERROR CHARACTERIZATION AND DIGITAL SIMULATION OF A PULSE-RATE INTEGRATOR. (Artículo de revista) International Journal of Electronics, 56 (4), pp. 521-531, 1984, (cited By 0). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Martinez1984521, title = {ERROR CHARACTERIZATION AND DIGITAL SIMULATION OF A PULSE-RATE INTEGRATOR.}, author = { E.C. Martínez and J.M. Tarela and C.D. Prada}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0021405311&partnerID=40&md5=07d4c75f69fca329cb223c9b903e3ba7}, year = {1984}, date = {1984-01-01}, journal = {International Journal of Electronics}, volume = {56}, number = {4}, pages = {521-531}, abstract = {The paper analyses the errors characterizing pulse-frequency representation of analogue signals and develops necessary conditions for good performance of these devices. In particular, pulse-frequency integrator (PRI) errors are studied and a digital simulation is accomplished.}, note = {cited By 0}, keywords = {}, pubstate = {published}, tppubtype = {article} } The paper analyses the errors characterizing pulse-frequency representation of analogue signals and develops necessary conditions for good performance of these devices. In particular, pulse-frequency integrator (PRI) errors are studied and a digital simulation is accomplished. |

## 1982 |

E.C. Martínez, J.M. Tarela DESIGN OF COMPUTING CIRCUITS FOR PULSE FREQUENCY CODED SIGNALS. (Artículo de revista) INT J ELECTRON, V 53 (N 5), pp. 401-418, 1982, (cited By 0). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{MARTINEZ1982401, title = {DESIGN OF COMPUTING CIRCUITS FOR PULSE FREQUENCY CODED SIGNALS.}, author = { E.C. Martínez and J.M. Tarela}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0020203988&partnerID=40&md5=98e3b5130fab64ceeb36a00b16f5dca0}, year = {1982}, date = {1982-01-01}, journal = {INT J ELECTRON}, volume = {V 53}, number = {N 5}, pages = {401-418}, abstract = {THIS PAPER DESCRIBES THE REALIZATION OF CIRCUITS WHICH OPERATE ON SIGNALS REPRESENTED IN PULSE-RATE FORM. FOR THIS, ONENEEDS A SERIES OF DIGITAL CIRCUITS SUCH AS THE BINARY RATE MULTIPLIER (BRM), ACCUMULATOR RATE MULTIPLIER (ARM), COUNTERS, FREQUENCY DIVIDERS ETC. TWO CHANNELS HAVE BEEN USED TO REPRESENT THE INFORMATION, ONE WITH A LOGICAL LEVEL INDICATINGTHE SIGN AND THE OTHER WITH THE FREQUENCY OF THE PULSE TRAIN INDICATING THE ABSOLUTE VALUE. FINALLY SOME APPLICATIONS OF THE DEVELOPED CIRCUITS ARE SHOWN.}, note = {cited By 0}, keywords = {}, pubstate = {published}, tppubtype = {article} } THIS PAPER DESCRIBES THE REALIZATION OF CIRCUITS WHICH OPERATE ON SIGNALS REPRESENTED IN PULSE-RATE FORM. FOR THIS, ONENEEDS A SERIES OF DIGITAL CIRCUITS SUCH AS THE BINARY RATE MULTIPLIER (BRM), ACCUMULATOR RATE MULTIPLIER (ARM), COUNTERS, FREQUENCY DIVIDERS ETC. TWO CHANNELS HAVE BEEN USED TO REPRESENT THE INFORMATION, ONE WITH A LOGICAL LEVEL INDICATINGTHE SIGN AND THE OTHER WITH THE FREQUENCY OF THE PULSE TRAIN INDICATING THE ABSOLUTE VALUE. FINALLY SOME APPLICATIONS OF THE DEVELOPED CIRCUITS ARE SHOWN. |

## 0000 |

E.R. Henquín, P.A. Aguirre Phenomenological model-based analysis of lithium batteries: Discharge, charge, relaxation times studies, and cycles analysis (Artículo de revista) AIChE Journal, 61 (1), pp. 90-102, 0000, (cited By 0). (Resumen | Enlaces | BibTeX | Etiquetas: ) @article{Henquín90, title = {Phenomenological model-based analysis of lithium batteries: Discharge, charge, relaxation times studies, and cycles analysis}, author = { E.R. Henquín and P.A. Aguirre}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84920171101&partnerID=40&md5=e5cdb07ed3c01f21cfe07ca1f53adc86}, doi = {10.1002/aic.14618}, journal = {AIChE Journal}, volume = {61}, number = {1}, pages = {90-102}, abstract = {The operation of lithium ion batteries in discharge and charge processes is addressed. A simple phenomenological model is developed to predict all variables values. A set of algebraic and differential equations is derived taking into account salt and lithium balances in electrodes, in the separator, and in particles. Balances are developed for finite volumes and appropriate average values of several variables such as concentrations, current densities, and electrochemical reaction rates are introduced. Definitions of current densities as volume fraction functions are critical issues in the computations. Experimental values taken from the literature for discharge processes are predicted very accurately. Constant salt concentration in the separator can be assumed and consequently, the model can be analytically solved. Charge and discharge times, initial cell capacity, lost capacity, and relaxation times are easily estimated from simple equations and cell parameters. The limiting processes taking place during cell discharge can be determined. Energy efficiency and capacity usage are quantified for cycles. © 2014 American Institute of Chemical Engineers.}, note = {cited By 0}, keywords = {}, pubstate = {published}, tppubtype = {article} } The operation of lithium ion batteries in discharge and charge processes is addressed. A simple phenomenological model is developed to predict all variables values. A set of algebraic and differential equations is derived taking into account salt and lithium balances in electrodes, in the separator, and in particles. Balances are developed for finite volumes and appropriate average values of several variables such as concentrations, current densities, and electrochemical reaction rates are introduced. Definitions of current densities as volume fraction functions are critical issues in the computations. Experimental values taken from the literature for discharge processes are predicted very accurately. Constant salt concentration in the separator can be assumed and consequently, the model can be analytically solved. Charge and discharge times, initial cell capacity, lost capacity, and relaxation times are easily estimated from simple equations and cell parameters. The limiting processes taking place during cell discharge can be determined. Energy efficiency and capacity usage are quantified for cycles. © 2014 American Institute of Chemical Engineers. |