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

ParamIni_LL_NRTL: Graphical User Interface (GUI) for the Selection of NRTL Initial Parameters for the Correlation of Ternary Liquid-Liquid Equilibrium Data (Type I, II, III and 0 (LL island), i.e. with 1, 2, 3 or 0 binary pairs partially miscibles)

The correlation of liquid-liquid equilibrium data is still currently a problem not fully resolved, especially for complex systems such as, those involving ionic liquid, where the high nonlinearity and non-convexity of the equations involved produce convergence problems, with a strong dependence on the initialization values used of the obtained solution. To avoid this situation, for the NRTL model, we have analyzed more than 200 LLE ternary systems (including type I, II, III and 0 or island, following the Treybal classification, Figure 1) in order to obtain a good representation of the different possible binodal curves and tie triangles that this model can reproduce satisfactorily, in a wide enough interval of values of the different parameters (taui,j, taui,j). All these systems have been parametrized regarding the main characteristics of the corresponding LLE, such as the number of binary subsystems partially miscible, the size and middle point of the binary tie-lines, the slope of the tie-lines, the location of the plate point, etc. With this parametrization, we have created a database and a new graphical user interface, GUI, that allows loading a set of liquid-liquid experimental data to obtain, using optimization algorithms and machine learning techniques, a consistent set of initial NRTL parameters that predicts a parametrized LLE near the experimental one. This set of parameters can be used now in any correlation data algorithm (using the corresponding equilibrium condition: isoactivity, minimum of the global Gibbs energy of mixing, or the Gibbs energy of mixing minor common tangent plane) to obtain the final rigorous solution. We believe that the present work can help researchers, professionals and students, in the task of correlating experimental liquid-liquid equilibrium data, in order to obtain consistent binary interaction parameters, taking into account that the correct calculation of the phase equilibrium is a key point in the optimal (efficient and sustainable) design of the corresponding processes and equipment. Related references: *Should we trust all the published LLE correlation parameters in phase equilibria? Necessity of their Assessment Prior to Publication. Fluid Phase Equilibria. 2017, 433, 243-252 (http://dx.doi.org/10.1016/j.fluid.2016.11.009). *GE Models and Algorithms for Condensed Phase Equilibrium Data Regression in Ternary Systems: Limitations and Proposals. The Open Thermodynamics Journal. 2011, 5, (Suppl 1-M5) 48-62 (http://dx.doi.org/10.2174/1874396X01105010048). * Checking Liquid-Liquid Critical Point Conditions and their Application in Ternary Systems. Industrial & Engineering Chemistry Research. 2012, 51(13), 5098-5102 (http://dx.doi.org/10.1021/ie202793r). *LLE data correlation using NRTL model for different types of binary systems: UCST, LCST and closed miscibility loops. Industrial & Engineering Chemistry Research. 2020, 59(17), 8469-8479 (https://doi.org/10.1021/acs.iecr.0c00141). * GMcal_TieLinesLL: Graphical User Interface (GUI) for Topological Analysis of Calculated GM Surfaces and Curves, including Tie-Lines, Hessian Matrix, Spinodal Curve, Plait Point Location, Miscibility Boundaries, etc. for Binary and Ternary Liquid-Liquid Equilibrium (LLE) Data. RUA 2015-2022. http://hdl.handle.net/10045/51725. *GMcal_TieLinesVL: Graphical User Interface (GUI) for the Topological Analysis of Experimental and Calculated GM Functions for Binary and Ternary (isobaric or isothermal) Vapor-Liquid Equilibrium (VLE) Data (including Tie-Lines, Derivatives, Distillation Boundaries, etc.). RUA 2022. http://hdl.handle.net/10045/122857. * Boundaries_LL_NRTL Graphical User Interface (GUI) for the Characterization of the NRTL model: Binary Spinodal Surfaces (in the tau(i,j)-tau(j,i)-xi space), LLE Maps and Miscibility Boundaries. RUA 2022 (http://hdl.handle.net/10045/121471). * What does the NRTL model look like? Determination of boundaries for different fluid phase equilibrium regions. AIChE Journal. 2022, e17805 (https://dx.doi.org/10.1002/aic.17805).University of Alicante y Ministerio de Ciencia e Innovación. PID2021-124139NB-C21: SUS4Energy, 2022/00666/001 (AEI)

Structural considerations in zeotropic distillation sequences with multiple feeds

The separation of multiple feed streams with some common components using sequences of distillation columns produces a rich space of alternatives that must be considered. In this work, we present the main structural characteristics of sequences generated when we want to take advantage of the synergies of common components in multiple feed streams to reduce both, energy consumption and the total number of distillation columns. In general, the sequence of separation tasks of the whole system can be obtained from the sequences of separation tasks of each one of the feeds. However, the integration in actual columns is not so straightforward and we must consider aspects like the optimal location of feeds in multiple-feed columns; and the alternatives of integration of common sub-mixtures (when possible) in actual columns. Besides, the optimal sequence of separation tasks for each feed is not necessarily the same when all of them are considered simultaneously. We show that the minimum number of actual columns, without considering further intensification, depends on the number of components in each feed and on the possibilities of integration of common sub-mixtures, so we extend the concepts of regular and basic column sequences to deal with these new situations. The examples show the potential savings in energy and number of columns compared to maintain isolated each feed; mixing the feed streams or an incorrect integration.The authors acknowledge financial support to the “Generalitat Valenciana” under project PROMETEO 2020/064

Graphical User Interface (GUI): ParamIni_LL_NRTL

33rd European Symposium on Computer Aided Process Engineering (ESCAPE33), June 18-21, 2023, Athens, Greece (Theme 8. Education and knowledge transfer: Poster 43,Board 107).In the present work, the NRTL model has been analyzed to obtain a good representation of the different ternary liquid-liquid equilibria that this thermodynamic model can reproduce satisfactorily. To do that, the main characteristics of different possible binary subsystems, ternary binodal curves (location in the composition diagram, size, tie-lines orientation, and plait point location), and LLLE tie triangles have been evaluated. With more than two hundred systems studied, the different behaviors have been parametrized to create, as the main objective of the present work, a database and a graphical user interface associated (ParamIni_LL_NRTL, Labarta et al. 2022. RUA: http://hdl.handle.net/10045/130017). This resource (publicly available for teaching and research uses) allows, given a set of ternary experimental LLE data to obtain by comparison with the elements of the database, a consistent set of initial NRTL parameters (taui,j, alfai,j) to start the corresponding correlation data procedure with enough guarantees.The authors gratefully acknowledge the financial support by the Ministry of Science and Innovation from Spain, under the project PID2021-124139NB-C21: SUS4Energy, 2022/00666/001 (AEI)

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

Improving some thermodynamic consistency tests for VLE data evaluation

Thermodynamics Conference 2013 (Statistical Mechanics and Thermodynamics Group of the Royal Society of Chemistry), The University of Manchester, 3-6 September 2013.The fundamental Gibbs-Duhem equation is the most widely referenced condition for consistency of the experimental VLE data, leading to a variety of thermodynamic consistency tests (TC tests). TC tests should be applied rigorously because deviations between the test results and VLE experimental data are usually attributed to the doubtful quality of the experimental data. Nevertheless, in many instances are the rough approximations involved in the applications of such TC tests the responsible of the bad results provided by a given experimental data set. In the present paper a method is suggested to calculate the term depending on the excess enthalpy (HE) that is rarely available and impedes rigorous calculation of the area test and the point (or differential) test in isobaric conditions. A relevant example of this problem is that the NIST algorithm uses the area test with the empirical Herington equation to estimate the term depending of HE, despite having been invalidated, and the point test is exclusively applied to isothermal and not to isobaric conditions. The comparison of the method proposed in this work with the standard procedures and data theoretically calculated demonstrates its capacity and validates experimental data sets otherwise improperly questioned.Financial support by means of the projects: MINECO. MAT2011-24991 and PROMETEO/2012/015

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

The understanding of the three-dimensional graphical behavior of the L-L-S phase equilibrium as a valuable tool to avoid spurious or incoherent experimental data

The complexity and variety of possible behaviors of the quaternary liquid-liquid, liquid-liquid-solid equilibrium at constant temperature are very high and, sometimes, are not well understood. It is not difficult to find references in literature where important misinterpretations and mistakes are committed as a consequence of applying a non-adequate experimental methodology and a lack of the spatial point of view. Thus, the objective of the present paper is to show several examples where special behaviors are selected to clarify some aspects concerning the experimental determination and graphical representation of liquid-liquid-solid equilibrium data, and emphasize the importance of the knowledge and consideration of the qualitative expected behavior of the system under study, obtained from the binaries.Universidad de Alicant