Browsing by Author "Mussati, Sergio Fabián"

Filter results by typing the first few letters
Now showing 1 - 12 of 12
  • Thumbnail Image
    Item
    A NGCC power plant with a CO2 post-combustion capture option : optimal economics for different generation/capture goals
    (Elsevier, 2013-11-13) Mores, Patricia Liliana; Godoy, Ezequiel; Mussati, Sergio Fabián; Scenna, Nicolás José
    Fossil fuel power plants are one of the major sources of electricity generation, although invariably release greenhouse gases. Due to international treaties and countries regulations, CO2emissions reduction is increasingly becoming key in the generators’ economics. NGCC power plants constitute a widely used generation technology, from which CO2capture through a post-combustion and MEA absorption option constitutes a technological challenge due to the low concentration of pollutants in the flue gas and the high energy requirements of the sequestration process. In the present work, a rigorous optimization model is developed to address the design and operation of power plants coupled to capture systems. The equations-oriented modeling strategy here utilized can address greenfield designs in which design and operating variables are simultaneously optimized, in order to ensure that the system will be able to meet process requirements at minimum cost. Then, an analysis of the electricity cost, CO2avoidancecost, energy penalties, as well as the optimal values of decision variables is thoroughly pursued. Different economic tradeoffs are comprised at the optimal solutions for the joint project, as given by the different discrete and continuous decisions that the designer needs to weight in order to achieve the desired generation and capture goals, including the number of parallel capture trains, the inherent efficiency of each recovery unit, and the overall emissions reduction rate. In this context, the joint optimization of the NGCC power plant with the amine-based capture option results in a novel configuration where 731 MW are optimally generated for supplying both the external demand and the capture plant energy requirements, and achieving an overall CO2emissions reduction rate of 82.1% by means of a three capture trains arrangement, where 13.4% of the flue gas stream is bypassed and 94.8% of the CO2gets recovered at each unit. This new generation/capture project features optimal values of its economic performance indicators, with an avoidance cost of 81.7 US$ per tonne of CO2 captured, which can Ministerio de Educación y Deportes Universidad Tecnológica Nacional Facultad Regional Rosario Universidad Tecnológica Nacional – Facultad Regional Rosario Zeballos 1341, Rosario, Santa Fe, Argentina only be secured by simultaneously optimizing the design and operating variables of both systems on a start-of-the-art optimization algorithm.
  • Thumbnail Image
    Item
    Aplicación de técnicas de programación matemática y métodos de integración de procesos para determinar la síntesis y el diseño óptimo de una planta de cogeneración de ciclo combinado
    (2017-03-29) Manassaldi, Juan Ignacio; Mussati, Sergio Fabián; Scenna, Nicolás José
    La presente tesis trata sobre el modelado matemático, simulación y optimización de ciclos combinados operando en forma desacoplada y acoplada a otros procesos, como por ejemplo, sistemas de utility y planta de captura de CO2. Precisamente, la tesis presenta modelos matemáticos utilizando programación matemática y metodologías “alternativas” para optimizar la configuración y el diseño de sistemas de cogeneración de vapor y electricidad. El planteamiento del problema de optimización se resolverá postulando una superestructura de configuraciones alternativas considerando la posibilidad de intercambios de calor en paralelo, serie y serie-paralelo entre la corriente de gas que abandona la turbina de gas y el fluido circulante del ciclo de vapor. De esta manera, la superestructura embebe numerosas alternativas para la configuración de los equipos las cuales son tenidas en cuenta simultáneamente por el algoritmo de optimización. La ventaja principal de este tipo de planteo es que al modificar las especificaciones de diseño permite determinar en forma automática la configuración óptima correspondiente. Durante el desarrollo de la tesis, se proponen y resuelven diferentes problemas de optimización considerando diferentes funciones objetivos y considerando fija la demanda de electricidad, según se detalla a continuación: 1) minimización del área total de transferencia de calor, 2) minimización del consumo de combustible, 3) minimización del costo total (inversión y costo de operación). Los modelos y metodologías de solución se aplican a la optimización de la configuración, diseño y operación de un sistema de cogeneración acoplado a distintos procesos, por ejemplo a un proceso de captura de CO2 utilizando aminas. Finalmente, la metodología es aplicada también para optimizar la síntesis y diseño de plantas de “utility” (configuración del ciclo combinado y configuración del sistema de turbinas y válvulas) considerando diferentes niveles de demandas de potencia y vapor. Las metodologías de solución se componen de procedimientos sistemáticos basados en el empleo de técnicas de Programación Mixta Entera No Lineal (MINLP), utilizando variables binarias para imponer restricciones de diseño de tipo estructural (configuración de los equipos) y variables continúas relacionadas con las condiciones de operación. Los resultados encontrados son comparados con los obtenidos por otros resolvedores tradicionales para modelos MINLP.
  • Thumbnail Image
    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 Fabián
    An 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.
  • Thumbnail Image
    Item
    Development of extrinsic functions for optimal synthesis and design : application to distillation-based separation processes.
    (2019-04-09) Manassaldi, Juan Ignacio; Mussati, Miguel Ceferino; Scenna, Nicolás José; Mussati, Sergio Fabián
    This work deals with the development and implementation of mathematical models in the General Algebraic Modeling System (GAMS) environment for optimization purposes, involving extrinsic functions that are executed outside GAMS from dynamic-link libraries (DLL) implemented in the programming language C. Three DLL libraries are developed to calculate thermodynamic properties: the Raoult's law for vapor-liquid equilibrium, the Non-Random Two-Liquid (NRTL) model, and the Peng–Robinson equation of state. A detailed description on how GAMS and DLL libraries interact is presented. Case studies dealing with the optimal design of multi-component distillation columns with increasing complexity levels are discussed. For the proposed case studies, the obtained results show that the usage of the proposed extrinsic functions allows to significantly enhance the model implementation compared to the traditional model implementation approach, and to considerably reduce the model size as well as the computational time required by the optimization algorithms.
  • Thumbnail Image
    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 Ceferino
    This 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.
  • Thumbnail Image
    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 Ceferino
    This 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.
  • Thumbnail Image
    Item
    Optimización de Plantas de Generación de Energía Eléctrica incluyendo Sistemas de Captura de CO2.
    (2015-03-20) Mores, Patricia Liliana; Mussati, Sergio Fabián; Scenna, Nicolás José
    La demanda de energía eléctrica se encuentra en constante crecimiento en el mundo actual, lo que exige la concreción de nuevas opciones de generación que resulten competitivas, en vista del amplio abanico de tecnologías que se encuentran disponibles para tal fin. Por otra parte, la reducción de emisiones de sustancias contaminantes (material particulado, gases con efecto invernadero) constituye un aspecto clave en la aprobación de nuevos proyectos, debido a la sanción de tratados internacionales y regulaciones ambientales progresivamente más restrictivas. Debido a la necesidad de satisfacer tanto la creciente demanda de energía como la reducción de las emisiones de CO2 a la atmósfera, se están realizando enormes esfuerzos para mejorar la performance de los sistemas de captura y compresión de CO2 acoplados a sistemas de generación de energía eléctrica. Específicamente, la integración de estos procesos es objeto de estudio en diferentes áreas de investigación. El presente trabajo de tesis propone modelar y optimizar procesos de captura de CO2 para el tratamiento de gases de combustión generados en plantas de producción de energía alimentadas por combustibles fósiles. Mediante el empleo de técnicas basadas en programación matemática, se pretende realizar el estudio del proceso global, considerando en la etapa de diseño preliminar tanto las variables operativas como las de dimensionamiento de cada uno de los equipos presentes. En función de lo expresado, se plantean los siguientes objetivos: Objetivo General: Contribuir en la búsqueda de soluciones tecnológicas conducentes a la disminución de emisiones gaseosas generadas en plantas de producción de vapor y electricidad, teniendo como meta principal una producción de energía eléctrica más limpia, de manera tal de no alterar el medioambiente. Objetivos Específicos: Generar un modelo matemático de optimización que permita abordar la síntesis y el diseño de plantas nuevas de cogeneración de vapor y electricidad incluyendo el tratamiento de sus emisiones gaseosas. Proponer una estrategia de solución para el modelo resultante, que garantice la obtención de soluciones óptimas al variar los principales parámetros del proceso. Se pondrá especial énfasis en la convergencia del modelo, evitando en lo posible soluciones óptimas locales, definiendo un procedimiento eficiente de inicialización de las variables. Estudiar y comparar, desde un punto de vista energético, económico y ambiental, la integración de la planta de producción de energía eléctrica con la planta de captura de CO2. El consumo de servicios auxiliares de ambos procesos es significativo, lo que implica elevados costos de operación. En consecuencia, es indispensable proponer un proceso integrado eficiente con el fin de disminuir el costo total anual, teniendo en cuenta los niveles umbrales permitidos de emisión de gases de efecto invernadero. Finalmente, a partir del planteo de diferentes casos de estudio y distintas funciones objetivo, se evaluará la performance del sistema captura de CO2 y del sistema “captura de CO2+generación” desde un punto de vista termodinámico y también económico.
  • Thumbnail Image
    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 Fabián
    This 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.
  • Thumbnail Image
    Item
    Optimization of triple-pressure combined-cycle power plants by generalized disjunctive programming and extrinsic functions.
    (2021-02-01) Manassaldi, Juan Ignacio; Mussati, Miguel Ceferino; Scenna, Nicolás José; Mussati, Sergio Fabián
    A new mathematical framework for optimal synthesis, design, and operation of triple-pressure steamreheat combined-cycle power plants (CCPP) is presented. A superstructure-based representation of the process, which embeds a large number of candidate configurations, is first proposed. Then, a generalized disjunctive programming (GDP) mathematical model is derived from it. Series, parallel, and combined series-parallel arrangements of heat exchangers are simultaneously embedded. Extrinsic functions executed outside GAMS from dynamic-link libraries (DLL) are used to estimate the thermodynamic properties of the working fluids. As a main result, improved process configurations with respect to two reported reference cases were found. The total heat transfer areas calculated in this work are by around 15% and 26% lower than those corresponding to the reference cases. This paper contributes to the literature in two ways: (i) with a disjunctive optimization model of natural gas CCPP and the corresponding solution strategy, and (ii) with improved HRSG configurations.
  • Thumbnail Image
    Item
    Process optimization and revamping of combined-cycle heat and power plants integrated with thermal desalination processes.
    (2021-06-06) Manassaldi, Juan Ignacio; Mussati, Miguel Ceferino; Scenna, Nicolás José; Morosuk, Tatiana; Mussati, Sergio Fabián
    Optimal revamping, sizing, and operation of an existing gas-turbine combined-cycle dual-purpose power/desalination plant – simultaneous electricity and freshwater generation – which operates with a heat recovery steam generation with one-pressure level (1P-HRSG) and a multi-stage flash desalination process, is addressed. The sizes and configurations of the gas turbine and desalination unit are kept the same as in the existing plant through the study. However, the 1P-HRSG is conveniently extended to twoor three-pressure levels with different exchanger arrangements, including steam reheating. To this end, a superstructure-based representation of the HRSG simultaneously embedding several candidate structures was proposed and a mixed-integer nonlinear programming model was derived from it. One revamping case consisted in maximizing the ratio between the freshwater production rate and the heat transfer area of HRSG, keeping unchanged the electricity generation rate (around 73 MW). It was found that the inclusion of a 3P-HRSG resulted in an increase of 13.782 kg⋅s−1 in the freshwater production, requiring 22753 m2 of heat transfer area less in the HRSG. Another revamping case consisted in maximizing the profit, contemplating the possibility to sell extra amounts of electricity and freshwater. Sale prices, for which producing extra electricity and freshwater is beneficial, were determined.
  • Thumbnail Image
    Item
    Reducción de las emisiones de gases con efecto invernadero (GEIs) en el sector energético mediante tecnologías no convencionales
    (2017-03-27) Arias, Ana Marisa; Mussati, Sergio Fabián; Scenna, Nicolás José
    Históricamente, en la provincia de Santa Fe las demandas de electricidad se satisfacen importando energía generada en otras provincias ya que carece de una matriz energética propia. Se conoce que en Argentina el 52 % de la electricidad se produce en centrales térmicas, que funcionan a gas o diesel; el 43 % en usinas hidroeléctricas, y apenas el 4 % es energía nuclear. A partir del año 2003 las demandas eléctricas en la mayoría de las provincias, incluyendo Santa Fe, se incrementaron fuertemente como consecuencia del crecimiento económico experimentado en diferentes sectores productivos tales como el agro, la construcción y la industria. Esto obligó tanto al gobierno nacional como provincial a impulsar un nuevo plan estratégico con el principal objetivo de aumentar la producción de electricidad y así poder reducir los efectos negativos de la crisis energética que afecta a todo el territorio nacional. A pesar de que las centrales de ciclo combinado operan con gas natural y en consecuencia son las que menos contaminan respecto a plantas que operan con carbón, requieren que los gases de combustión generados deban ser tratados necesariamente antes de ser emitidos al ambiente. La corriente de gases exhaustos contiene uno de los principales responsables del calentamiento global, el CO2. Diferentes estudios revelan que para las próximas décadas la concentración de CO2 en el ambiente aumentaría a ritmos más acelerados en caso que no se adopten las medidas y acciones necesarias tendientes a disminuir dichas emisiones. De este modo resulta evidente la imperiosa necesidad de investigar y proponer soluciones efectivas para reducir las emisiones de gases con efecto invernadero. Algunas de las acciones tendientes a reducir las emisiones de CO2 procedentes de la combustión de combustibles fósiles para la producción de energía, debieran apuntar a: 1) uso racional de la energía generada (aumento de la eficiencia en los procesos de conversión), 2) utilizar combustibles que tengan menores emisiones (energías renovables, gas natural), 3) captura y almacenamiento del CO2 procedente de la combustión. En este sentido, esta tesis se enmarca en el punto 3) ya que se propone investigar y desarrollar procesos eficientes para tratar las emisiones generadas en las plantas de producción de energía eléctrica que contribuyen al efecto invernadero, en especial el CO2.
  • Thumbnail Image
    Item
    Renewable energy-water nexus: optimal design of an integrated system including a single flash geothermal plant, kalina cycle and reverse Osmosis desalination unit
    (2023-12) Manassaldi, Juan Ignacio; Mussati, Miguel Ceferino; Incer-Valverde, Jimena; Morosuk, Tatiana; Mussati, Sergio Fabián
    Resumen de artículo presentado en la Conferencia. This paper addresses the optimization of a dual-purpose desalination system based on a geothermal flash cycle, Kalina cycle, and a reverse osmosis seawater desalination plant. A nonlinear mathematical programming (NLP) optimization is developed and implemented in GAMS – general algebraic modeling system – which is a high-level modeling environment widely used in Process System Engineering PSE. CONOPT, which is a derivate-based optimization algorithm, is used as an NLP solver. Also, dynamic-link libraries (DLLs) are developed and implemented in the programming code C with the aim of rigorously calculating the thermodynamic properties of all process streams. The DLLs are systematically called from the GAMS environment. In addition, a solution strategy has been developed to facilitate model convergence. In this approach, several models are sequentially solved, starting with the simplest model progressing to solving a more complex model. As a result, the optimal sizing and operating conditions of all process units are simultaneously obtained. Finally, a sensitivity analysis of the key model parameters, electrical power, and freshwater demands on the optimization criterion is discussed. The proposed mathematical model is a powerful decision-making tool for the design and synthesis of integrated geothermal power and desalination processes, which can be used as either a simulator or an optimizer, depending on the number of freedom degrees specified by the user.