Facultad Regional Rosario
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Item Modelado matemático, validación y análisis del proceso de extracción de antocianinas en harina de orujos tintos a diferentes temperaturas.(2018-07) Bonfigli, Mónica Beatriz; Chiandoni, Florencia Soledad; Kraft, Romina Alejandra; Reinheimer, María AgustinaLa extracción sólido-líquido es una operación unitaria ampliamente utilizada para extraer compuestos biológicos de interés de diversas matrices alimentarias. En el presente trabajo se ha desarrollado un modelo matemático para el análisis del proceso de extracción de antocianinas en orujos tintos. El modelo está formado tanto por ecuaciones algebraicas como diferenciales y fue desarrollado en el software de optimización GAMS (General Algebraic Modeling System). Para la implementación de las ecuaciones a derivadas parciales en el modelo se utilizó el método implícito de discretización. Para la validación del modelo, se llevaron a cabo corridas a diferentes temperaturas de extracción (25, 45 y 65 ºC), utilizando como solvente extractor una mezcla hidro-alcohólica (50:50). Se observó un buen ajuste entre los valores óptimos obtenidos y experimentales, observándose que se obtiene una mayor eficiencia de extracción a 45 ºC.Item Optimal management policies for the economic optimal dispatch of a hydrothermal power grid.(2016-06) D' Emanuele Ares, Carolina; Godoy, Ezequiel; Scenna, Nicolás JoséPresentación en diapositivas realizada en : EngOpt 2016, 19 al 23 de Junio de 2016, Foz de Iguazú, Brasil.Item Economic implications when considering availability in the optimal design and operation of a NGCC power plant.(2012-09) Godoy, Ezequiel; Benz, Sonia Judith; Scenna, Nicolás José- Traditionally, power plants are designed to fulfll a pre-specified external demand, usually by oversizing the existing equipment, which implies excessive capital costs and might even result in designs that cannot satisfy demands for certain situations. Therefore, in order to avoid large economic penalties if power demand is not satisfied, the design and operation of such systems need to consider the effect of reliability considerations and maintenance funds allocation on the system design and operative characteristics. In the present work, a MINLP formulation is developed to address the design and operation of power plants while considering the implications of a statespace availability modeling approach and of a comprehensive maintenance funds allocation policy. Then, the decision variables are optimized simultaneously throughout several maintenance and failure situations that configure difeerent scenarios, in order to ensure that the plant will be able to cope with them while meeting the expected requirements at minimum cost.Item Implications of a state-space approach for the economic optimal design of a NGCC power plan.(2014-10) Godoy, Ezequiel; Benz, Sonia Judith; Scenna, Nicolás JoséA detailed state-space approach is here embedded in the optimization model for the economic design of a new natural gas combined cycle (NGCC) power plant. This proposal comprehensively quantifies the impact of different adopted values for two critical parameters: the number of simultaneously and independently failed components, and the number of simultaneous events. The former depicts the maximum number of components (gas turbines, steam turbine, HRSGs, auxiliary services, etc.) that seem feasible to fail because of independent causes at the same time. The latter describes the maximum number of transitions between operating conditions, which is directly linked to the amount of available maintenance resources (personnel, parts, etc). Implications of a wide array of values for these two parameters over the economic optimal solutions are thoroughly discussed, where it is observed that more accurate and detailed estimations of the expected economic performance for the project are attained.Item Development of optimization models for food processing operations with focus on adding value to by products.(2018-09) Reinheimer, María Agustina; Godoy, Ezequiel; Balzarini, María Florencia; Accoroni, CeciliaDevelopment of optimization models for food processing operations with focus on adding value to by products.. (Resumen)Item Strategy for optimization of CCGT power plants by solving a simple nonlinear equations system and constraint equations.(2010-07) Godoy, Ezequiel; Benz, Sonia Judith; Scenna, Nicolás JoséA strategy for the solution of the optimization problem of minimum cost of combined cycle gas turbine power plants is presented. Specific relationships, valid at the optimal solution, among selected decision variables are used to introduce new constraints to the optimization problem. Then, the feasible region is reduced to a “single point”, and the resolution strategy becomes equivalent to solving the resultant set of non-linear equations system and constraint equations so achieved to optimize the system. This approach can also be used to achieve reduced models for real time optimization problems.Item Optimal design of a two-stage membrane system for hydrogen separation in refining processes.(2018-10-31) Arias, Ana Marisa; Mores, Patricia Liliana; Scenna, Nicolás José; Caballero, José Antonio; Mussati, Sergio Fabián; Mussati, Miguel CeferinoThis paper fits into the process system engineering field by addressing the optimization of a two-stage membrane system for H2 separation in refinery processes. To this end, a nonlinear mathematical programming (NLP) model is developed to simultaneously optimize the size of each membrane stage (membrane area, heat transfer area, and installed power for compressors and vacuum pumps) and operating conditions (flow rates, pressures, temperatures, and compositions) to achieve desired target levels of H2 product purity and H2 recovery at a minimum total annual cost. Optimal configuration and process design are obtained from a model which embeds different operating modes and process configurations. For instance, the following candidate ways to create the driving force across the membrane are embedded: (a) compression of both feed and/or permeate streams, or (b) vacuum application in permeate streams, or (c) a combination of (a) and (b). In addition, the potential selection of an expansion turbine to recover energy from the retentate stream (energy recovery system) is also embedded. For a H2 product purity of 0.90 and H2 recovery of 90%, a minimum total annual cost of 1.764 M$·year−1 was obtained for treating 100 kmol·h−1 with 0.18, 0.16, 0.62, and 0.04 mole fraction of H2, CO, N2, CO2, respectively. The optimal solution selected a combination of compression and vacuum to create the driving force and removed the expansion turbine. Afterwards, this optimal solution was compared in terms of costs, process-unit sizes, and operating conditions to the following two suboptimal solutions: (i) no vacuum in permeate stream is applied, and (ii) the expansion turbine is included into the process. The comparison showed that the latter (ii) has the highest total annual cost (TAC) value, which is around 7% higher than the former (i) and 24% higher than the found optimal solution. Finally, a sensitivity analysis to investigate the influence of the desired H2 product purity and H2 recovery is presented. Opposite cost-based trade-offs between total membrane area and total electric power were observed with the variations of these two model parameters. This paper contributes a valuable decision support tool in the process system engineering field for designing, simulating, and optimizing membranebased systems for H2 separation in a particular industrial case; and the presented optimization resultsprovide useful guidelines to assist in selecting the optimal configuration and operating mode.Item Membrane-based processes: optimization of hydrogen separation by minimization of power, membrane area, and cost.(2018-11-12) Mores, Patricia Liliana; Arias, Ana Marisa; Scenna, Nicolás José; Caballero, José Antonio; Mussati, Sergio Fabián; Mussati, Miguel CeferinoThis work deals with the optimization of two-stage membrane systems for H2 separation from off-gases in hydrocarbons processing plants to simultaneously attain high values of both H2 recovery and H2 product purity. First, for a given H2 recovery level of 90%, optimizations of the total annual cost (TAC) are performed for desired H2 product purity values ranging between 0.90 and 0.95 mole fraction. One of the results showed that the contribution of the operating expenditures is more significant than the contribution of the annualized capital expenditures (approximately 62% and 38%, respectively). In addition, it was found that the optimal trade-offs existing between process variables (such as total membrane area and total electric power) depend on the specified H2 product purity level. Second, the minimization of the total power demand and the minimization of the total membrane area were performed for H2 recovery of 90% and H2 product purity of 0.90. The TAC values obtained in the first and second cases increased by 19.9% and 4.9%, respectively, with respect to that obtained by cost minimization. Finally, by analyzing and comparing the three optimal solutions, a strategy to systematically and rationally provide ‘good’ lower and upper bounds for model variables and initial guess values to solve the cost minimization problem by means of global optimization algorithms is proposed, which can be straightforward applied to other processes.Item Cost-based comparison between membrane systems and chemical absorption processes for CO2 capture from flue gas.(2019-05-09) Arias, Ana Marisa; Mores, Patricia Liliana; Scenna, Nicolás José; Caballero, José Antonio; Mussati, Miguel Ceferino; Mussati, Sergio FabiánAn optimization study of membrane-based separation systems for carbon dioxide capture from flue gas of power plants is conducted, considering the possibility of employing up to four stages and using diverse options to create the required driving force. By proposing a superstructure-based model, the number of stages, recycle options, use of feed compression and/or permeate vacuum, driving force distribution along each membrane stage, operating conditions and equipment sizes are simultaneously optimized in order to minimize the total annual cost at high capture ratios and purity targets. Thus, different optimal arrangements are obtained and the total cost is reduced in about 20% compared without employing vacuum. Besides the optimal number of stages diminishes with decreasing purity, but it is independent of the capture ratio. Also, the total cost decreases with the increase of the membrane permeance requiring lower values of operating pressure and membrane areas. Permeance values higher than 2400 GPU lead to lower number of stages and recycles for the same separation target. By contrast, a sensitivity analysis shows that the total cost increases with the increase of the electricity price, capacity factor, and capital recovery factor, which are the more influential parameters in the objective function. Despite new optimal operating and design conditions are obtained when these parameters vary, no modifications in the optimal arrangement are observed.Item Optimization of the design, operating conditions, and coupling configuration of combined cycle power plants and CO2 capture processes by minimizing the mitigation cost.(2017-10-04) Mores, Patricia Liliana; Manassaldi, Juan Ignacio; Scenna, Nicolás José; Caballero, José Antonio; Mussati, Miguel Ceferino; Mussati, Sergio FabiánThis paper deals with the optimization of the coupling between a natural gas combined cycle (NGCC plant and a post-combustion CO2 capture process by minimizing the mitigation cost – defined as the ratio between the cost of electric power generation and the amount of CO2 emitted per unit of total net electric power generated – while satisfying the design specifications: electric power generation capacity and CO2 capture level. Three candidate coupling configurations, which differ in the place where the steam is extracted from, are optimized using detailed and rigorous models for both the NGCC and the CO2 capture plants. By comparing the mitigation cost of each configuration, the optimal integration configuration and the corresponding optimal sizes and operating conditions of all process units (steam turbines, gas turbines, heat recovery steam generators HRSGs, absorption and regeneration columns, reboilers and condensers, and pumps) are provided. In the computed optimal solution, the steam required by the CO2 capture plant is extracted from both the steam turbine and the HRSG (evaporator operating at low pressure), and the mitigation cost is 90.88 $/t CO2. The optimal solution is compared with suboptimal solutions corresponding to the other two candidate coupling schemes. These solutions are compared in detail regarding capital investment.