Resume of the extension of the Ponchon and Savarit method for designing ternary rectification columns

This work presents a summary of the analytical extension of the classical Ponchon and Savarit method for the design of binary distillation columns to ternary systems. For a given feasible separation, convergence is almost always guaranteed in calculation times comparable to those used by commercial simulation packages. However, in this case the total number of stages and the optimal feed location are simultaneously determined. For ternary mixtures it is possible graphical representation keeping all the intuitive characteristics of the original method for binary mixtures. The presented approach include the possibility of approximate (with interpolation, correlation and intersection methods) or rigorous calculations of mass and energy balances and equilibrium relations and the direct calculation of the minimum number of equilibrium stages and the optimum feed point location for a specific product separation with a specified reflux ratio. The distillate flow rate and the reflux ratio can be optimised in an outer loop providing the method a great flexibility.University of Alicante and Institute of Culture Juan Gil Alber

Reacciones de oxidación y reducción (Redox): ecuaciones, diagramas y relaciones con otros equilibrios

Sistemas redox. Aplicación de la ecuación de Nernst a distintos tipos de sistemas. Factores que modifican el potencial redox. Reacciones de transferencia electrónica. Constante de equilibrio y potencial de equilibrio. Representaciones gráficas: Diagrama log C-E y sus aplicaciones al estudio de las reacciones redox. Sistemas redox del agua. Análisis de sistemas-combinación de diagramas.Universidad de Alicant

Aprendizaje de conceptos complejos en Oceanografía a través del diseño de aplicaciones en Matlab: Una estrategia para motivar al alumnado e introducirlo en la programación

Este trabajo pretende resolver un problema detectado en el alumnado de la asignatura Oceanografía Física del Grado en Ciencias del Mar. Dicho problema está relacionado con la dificultad del alumnado actual para sentirse motivado ante el aprendizaje de conceptos complejos en Física, Química y Matemáticas así como adquirir las competencias y capacidades asociadas a dicho concepto. Se ha escogido un concepto complejo: la obtención del flujo geostrófico en el océano. El trabajo presenta un cuestionario inicial de evaluación previa tras la explicación del concepto en una clase magistral, el posterior desarrollo de una sesión de aprendizaje utilizando simulaciones virtuales y programación en Matlab así como un cuestionario final para evaluar el grado de satisfacción así como de adquisición de conocimientos y competencias tras realizar la actividad para así poder extraer conclusiones de su actividad. Aunque los cuestionarios y la sesión no se podrán aplicar hasta el curso académico 2016-17, esperamos que mejore significativamente el aprendizaje en clase, cree un ambiente favorable entre el alumnado para utilizar las nuevas tecnologías y la programación y pueda aplicarse posteriormente a otros conceptos de esta u otras asignaturas.Universidad de Alicant

Analysis of the Zone Connecting Consecutive Sectors in Generalized Distillation Columns by Using the Ponchon-Savarit Method

Ponchon-Savarit is a classical graphical method for the design of binary distillation columns. This method is still widely used, mainly with didactical purposes, though it is also valid for preliminary calculations. Nevertheless, no complete description has been found in books and situations such as different thermal feed conditions, multiple feeds, possibilities to extract by-products or to add or remove heat, are not always considered. In this work we provide, a systematic analysis of the Ponchon-Savarit method by developing generalized equations for the operating lines or difference points, as well as a consistent analysis of what may happen in the zone between two consecutive trays of the corresponding sectors separated by a lateral stream of feed, product, or a heat removal or addition. The graphical interpretation of all situations shown allows a clarifying view of the different possibilities in the rectifying column and completes the existing literature about this method

Mapping Binary Liquid-Vapor or Liquid-Liquid-Vapor Equilibria Regions, including the Different Azeotropic Behaviours, as a Function of the NRTL Binary Parameters

13th Mediterranean Congress of Chemical Engineering (Sociedad Española de Química Industrial e Ingeniería Química, Fira Barcelona, Expoquimia), Barcelona, September 30-October 3, 2014As it is very well know, the synthesis and design of separation processes requires the use of models to represent the phase equilibrium data, which involves the previous correlation of experimental data to obtain the values of the corresponding parameters. In previous works, we have studied the capabilities and limitations of the classical GE models used in phase equilibrium data correlations, such as NRTL model, in representing the behaviour of different LV, LL and LLS equilibrium data. In the preset work, the relations between the binary parameters Aij of the NRTL model and the existence of different equilibrium regions (i.e.: LV, LL or LLV), as well as the different possible azeotropic behaviours are analyzed for different component systems. The Gibbs free enthalpy curve and the corresponding y-x and T-x,y diagrams along a matrix of Aij parameters has been studied within a range including the typical values observed in DECHEMA Chemistry Data Series

Robust program for LLSE data correlation of ternary systems

The existing commercial software packages (like Dechema Data Preparation Package (DPP) and the regression utilities of Chemical Engineering simulators like Chemcad) have been widely used and their extensive capabilities are well-known. Nevertheless, and as long as LLE calculations is concerned, they have been designed for the simplest equilibrium behaviour. For example, for ternary systems it is only possible the correlation of type 1 and type 2 LLE data. None of these applications allows for the correlation of type 0 LLE, type 3 LLLE or type 4 LLSE systems. To enable a possible extension of such software, a robust calculation algorithm to compute phase equilibria among condensed phases for all these more complicated behaviours has been developed.Vicepresidency of Research (University of Alicante) and Generalitat Valenciana (GV/2007/125)

Adoption of improved varieties in adverse climatic conditions: Evidence from Nicaragua

This presentation summarizes the main results of a study made in Nicaragua to estimate the adoption of improved bean varieties (IVs) across different climatic environments, and the yield differences between adopters and non-adopters. We implemented a farmer-level survey representative of the most productive bean regions in the country. The results show that when comparing dry vs. non-dry regions ("corridors"), yields are 10.9% lower in the dry region; 29-31% of farmers have adopted IVs in non-dry and dry regions, respectively; and 28-29% of the bean area was planted to IVs in non-dry and dry regions, respectively. Although IV yields are statistically the same to non-IV yields (farmer-reported use of IVs), in dry regions, improved bean varieties yield 14.7% more than non-IVs, which is enough to feed 6-7 people for a year. This yield advantage (of IVs) dissapears under extreme dry conditions

Bean production systems in Nicaragua: technology adoption in the face of climate adversity

We documented the bean production systems in Nicaragua, focusing on the adoption of improved bean varieties (IVs) under adverse climatic (rainfall) conditions and its economic effect on adopting households. Using data from a representative sample of 589 farmers (341 located in the dry corridor), we demonstrate statistical differences in the socioeconomic characteristics, farm characteristics, and bean management practices between IV adopters and non-adopters, and by region (i.e., dry vs. non-dry corridors). Farmers in the dry corridor obtained significantly lower yields compared to farmers in non-dry areas. Further, 30% of farmers in Nicaragua had adopted at least one improved bean variety in the seasons of interest, and 28.3% of the bean area was grown with IVs. Adopting an IV positively affected yields --farmers obtained 11% higher yields-- but had no statistically significant effect on profits. The results highlight the importance of growing improved bean varieties under adverse rainfall conditions, as farmers who adopted an IV in the dry corridor obtained 13.2% higher yields than non-adopters in the same region. We did not find statistical yield differences between IV adopters and non-adopters in non-dry regions

Correlation of three-liquid-phase equilibria involving ionic liquids

The difficulty in achieving a good thermodynamic description of phase equilibria is finding a model that can be extended to a large variety of chemical families and conditions. This problem worsens in the case of systems containing more than two phases or involving complex compounds such as ionic liquids. However, there are interesting applications that involve multiphasic systems, and the promising features of ionic liquids suggest that they will play an important role in many future processes. In this work, for the first time, the simultaneous correlation of liquid–liquid and liquid–liquid–liquid equilibrium data for ternary systems involving ionic liquids has been carried out. To that end, the phase diagram of the water + [P6 6 6 14][DCA] + hexane system has been determined at 298.15 K and 323.15 K and atmospheric pressure. The importance of this system lies in the possibility of using the surface active ionic liquid to improve surfactant enhanced oil recovery methods. With those and previous measurements, thirteen sets of equilibrium data for water + ionic liquid + oil ternary systems have been correlated. The isoactivity equilibrium condition, using the NRTL model, and some pivotal strategies are proposed to correlate these complex systems. Good agreement has been found between experimental and calculated data in all the regions (one triphasic and two biphasic) of the diagrams. The geometric aspects related to the Gibbs energy of mixing function obtained using the model, together with the minor common tangent plane equilibrium condition, are valuable tools to check the consistency of the obtained correlation results

Simultaneous VLLE data correlation for ternary systems: Modification of the NRTL equation for improved calculations

Simultaneous correlation of vapour–liquid–liquid equilibrium (VLLE) data is hardly ever attempted in literature with one common set of parameters for all the equilibrium regions present in the systems. It is common practice to obtain different sets of parameters for VLE, LLE and VLLE regions when experimental equilibrium data for ternary systems are fitted with a given model (e.g. an activity coefficient model for the liquid phase). Besides, when dealing with the correlation of VLE for ternary systems, it is quite frequent to obtain different sets of parameters for each one of the three binary subsystems from those obtained when exclusively binary VLE data are correlated. In the present work, the simultaneous correlation of all the equilibrium regions in the ternary VLL system is attempted. The objective function and the restrictions of the system are clearly presented. In addition, a simple modification of the NRTL equation for the Gibbs energy of mixing (GM) is proposed including a ternary term and a binary correction based on the Wohl equation. This modification has significantly improved the quality of the results obtained in the simultaneous correlation of different equilibrium regions