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 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.Item Membrane superstructure optimization for carbon capture from cement plants. Water content influence on optimal solution.(2023) Arias, Ana Marisa; Scenna, Nicolás José; Mores, Patricia LilianaA four-membrane superstructure, embedding different connection alternatives and driving force generation options, was extended to consider a four-component wet flue gas mixture. Three case scenarios were assessed for treating a flue gas stream from a cement plant. By minimizing the specific total annual cost (sTAC), each case converged to a distinct local optimal arrangement, achieving the same separation target (90% CO2 recovery and 95% CO2 purity on the concentrated stream), thus highlighting the versatility of the model. In terms of the same superstructure and cost model, the optimal solution for capturing CO2 from wet flue gases is approximately 1.5 times higher than that of a dry mixture. A commonly published optimal two membrane-stage configuration fails to achieve high separation targets, even with low water content. The most cost-effective approach is to eliminate water at the beginning of the process. The energy consumed for CO2 pumping and compression is offset by energy generated during retentate expansion, resulting in a surplus that reduces the overall energy consumption to drive the process.Item Evaluation of solar thermal energy capture and storage alternatives for indirect steam generation: a case study.(2023-03-26) Zoratti, G.; Mores, Patricia Liliana; Godoy, EzequielThis study analyses the integration of a solar thermal plant for indirect steam generation in a typical industrial process with thermal energy requirements. Solar irradiation is computed using a validated predictive model in Santa Fe province, Argentina. Three configurations are proposed, consisting of parabolic trough collectors and thermal storage tanks. Performance indicators, such as generated energy, resulting solar fraction (the fraction of the industrial process' thermal requirements met by solar energy), and necessary solar field area, are evaluated for each configuration. A specific energy map is generated, showing the solar generation potential at each location. For required solar fractions of 20-25%, incorporating a thermal storage system does not provide any benefits as the solar plant does not produce enough energy to contribute to the industrial process during winter months. For required solar fractions of 30-35%, the resulting solar fraction can be increased to 42-45% with additional capture area and thermal storage capacity. For required solar fractions of 37-40%, the thermal storage improves the efficiency of the solar plant, resulting in a solar fraction of 50-60%, allowing the industrial process to receive energy for at least 6 hours a day throughout the year. It is concluded that these configurations are suitable for providing a portion of the industrial process' thermal requirements.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 JoséFossil 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.