FRRo - I+D+i - Artículos en Revistas
Permanent URI for this collectionhttp://48.217.138.120/handle/20.500.12272/1297
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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.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 FabiánThis 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.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 FabiánA 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.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 FabiánOptimal 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.Item A risk– based design of ammonia refrigeration systems in food manufacturing plants.(2019-01) Biscotti, Paola Silvina; Reinheimer, María Agustina; Scenna, Nicolás JoséThis paper presents a risk-based design procedure of ammonia based refrigeration processes taking into account the allocation of the manufacturing plant and the surrounding environment vulnerability at early stages of process design. In addition, the proposed design framework allows the integration of a process simulator with vulnerability assessment packages. As a case study, the design of the refrigeration system for a surimi manufacturing plant is presented.Item Obtención de correlaciones convexas para el análisis de los efectos causados por xxplosiones Tipo BLEVE : estimación de distancias de seguridad en función de niveles de vulnerabilidad especificados.(2020-12-01) Kraft, Romina Alejandra; Mores, Patricia Liliana; Scenna, Nicolás JoséEn los últimos años, debido al gran número de accidentes catastróficos en el sector industrial, la obtención de una metodología cuya aplicación contribuya a la mitigación de los daños causados ha adquirido gran importancia. En este trabajo, se obtienen dos correlaciones que describen el comportamiento de un evento específico (explosión tipo BLEVE) por medio de una combinación lineal de funciones convexas simples entre las principales variables: energía interna total del sistema al momento de la explosión, distancia y nivel de daño/tipo de receptor. La primera permite estimar la distancia de seguridad frente a una explosión de cualquier sustancia peligrosa y la segunda, el nivel de daño (expresado en términos de sobrepresión) ocasionado a un receptor ubicado a una cierta distancia del evento catastrófico. En trabajos futuros, se pretende emplear las mismas en la optimización de diseño inherentemente seguro de layout.Item BLEVE : estimación de distancias seguras basándose en variables de diseño.(2022-03-11) Kraft, Romina Alejandra; Mores, Patricia Liliana; Scenna, Nicolás JoséEntre los eventos accidentales más peligrosos se encuentran las explosiones BLEVE. Las graves consecuencias ocasionadas por la onda expansiva generada hacen indispensable su análisis. Los modelos matemáticos disponibles son complejos en cuanto a la cantidad de datos y esfuerzo computacional requeridos para su resolución. En este trabajo, se presenta un modelo simple y directo para la estimación de distancias seguras entre una fuente de explosión y un receptor caracterizado por el nivel de vulnerabilidad. La obtención del mismo se lleva a cabo mediante la selección de variables de diseño convenientes y el análisis de su influencia en los resultados brindados por un modelo matemático con fundamento teórico (modelo base), la formulación de una única expresión matemática con parámetros a determinar (modelo simple) y la resolución de un problema de optimización en el que se maximiza el R2 que resulta de la comparación entre ambos modelos. Finalmente, se demuestra una muy buena performance del modelo propuesto, permitiendo la obtención confiable de distancias seguras desde las primeras etapas del diseño.