2,494 research outputs found

    Vapour reactive distillation process for hydrogen production by hi decomposition from hi-i2-h2o solutions

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    In this contribution, a sequential and hierarchical approach for the feasibility analysis and the preliminary design of reactive distillation columns is extended to systems involving vapour phase chemical reaction and is successfully applied to the HI vapour phase decomposition to produce H2. The complex phase and physico chemical behaviour of the quaternary HI-H2-I2-H2O system is represented by the Neumann’s thermodynamic model and instantaneous vapour phase chemical equilibrium is assumed. Then, from minimal information concerning the physicochemical properties of the system, three successive steps lead to the design of the unit and the specification of its operating conditions: the feasibility analysis, the synthesis and the design step. First, the analysis of reactive condensation curve map method (rCCM), assuming infinite internal liquid and vapour flow rate and infinite reflux ratio, is used to assess the feasibility of the process. It determines the column structure and estimates the attainable compositions. These results are used as inputs data for the synthesis step. Based on the boundary value design method (BVD), considering finite internal liquid and vapour flow rate and finite reflux ratio while neglecting all thermal effects and assuming a constant heat of vaporisation, the synthesis step provides more precise information about the process configuration (minimum reflux ratio, number of theoretical stages, localisation and number of reactive plates, position of the feed plate). Finally, the BVD method results are used to initialise rigorous simulations, based on an equilibrium stage model with energy balance, to estimate the reflux ratio taking into account thermal effect on the process. The resulting design configuration consists in a single feed and entirely reactive distillation column. The column operates under a pressure of 22 bars. The feed of the reactive distillation column, coming from the Bunsen reaction section [xHI=0.10; xI2=0.39 xH2O=0.51], is at its boiling temperature. The residue consists in pure iodine. Water and produced hydrogen are recovered at the distillate. The column operates at a reflux ratio of 5 and is composed of 11 theoretical plates including the reboiler and the partial condenser with the feed at the stage 10 (counted downwards). The obtained HI dissociation yield is 99.6%

    Study of the reactive distillation in the production of isobutyl acetate

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    This work presents a study of a reactive distillation process for the production of Isobutyl acetate, from the fundamentals of the operation like the phase equilibria and the reaction kinetics, to the conceptual design. Experimental phase equilibrium data was evaluated, and the quaternary mixture interactions were accurately described using an activity coefficients model for the liquid phase, and a viral equation of state for the vapor phase as described in Chapter one. In Chapter two a mole-based kinetic expression was adjusted to describe the esterification process using an heterogeneous catalyst. Then, a conceptual design of the reactive distillation process, coupling the phase equilibria and the reaction kinetics, was done in order to obtain a suitable configuration for an industrial scale process to produce Isobutyl acetate. Finally, rigorous simulations and optimization enabled to obtain the best operating conditions of the reactive distillation process for isobutyl acetate production at the industrial scale presented in Chapter three.Este trabajo presenta un estudio del proceso de producción de Isobutil acetato por medio de destilación reactiva, desde los fundamentos de la operación como el equilibrio de fases y la cinética de reacción, hasta el diseño conceptual. Se evaluó información experimental del equilibrio de fases y las interacciones de la mezcla cuaternaria se describieron adecuadamente usando un modelo de coeficientes de actividad para la fase liquida y una ecuación de estado para la fase vapor. Una expresión cinética con base en fracciones molares fue desarrollada para describir el proceso de esterificación usando un catalizador heterogéneo. Posteriormente, se desarrolló el diseño conceptual del proceso de destilación reactiva empleando simultáneamente el equilibrio de fases y la cinética previamente obtenidos. Finalmente, con base en simulación rigurosa y optimización del proceso de destilación reactiva se obtuvieron las condiciones de operación masa adecuadas para la producción de Isobutil acetato por destilación reactiva a escala industriade esta tesis se publicaron 3 articulos cientificos: Martínez, A.F., Sánchez, C.A., Orjuela, A., Rodríguez, G. 2020. Isobutyl acetate production by reactive distillation. Non-reactive phase equilibrium and topological analysis. Fluid Phase Equilibria. 516: 112612. DOI: 10.1016/j.fluid.2020.112612 Martínez, A. F., Sánchez, C. A., Orjuela, A., Gil, I. D., Rodríguez, G. 2020. Isobutyl acetate by reactive distillation. Part II. Kinetic study. Chem. Eng. Res. Des. 160: 447-453. DOI: 10.1016/j.cherd.2020.06.023. Martínez, A. F., Rodríguez, J.S., Sánchez, C. A., Orjuela, A., Rodríguez, G. 2020. Isobutyl acetate by reactive distillation. Part III. Conceptual design, simulation and optimization. Chem. Eng. Process. Vol.155:  108059. DOI: 10.1016/j.cep.2020.108059.Maestrí

    Preliminary Design of Reactive Distillation Columns

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    A procedure that combines feasibility analysis, synthesis and design of reactive distillation columns is introduced. The main interest of this methodology lies on a progressive introduction of the process complexity. From minimal information concerning the physicochemical properties of the system, three steps lead to the design of the unit and the specification of its operating conditions. Most of the methodology exploits and enriches approaches found in the literature. Each step is described and our contribution is underlined. Its application is currently limited to equilibrium reactive systems where degree of freedom is equal to 2 or less than 2. This methodology which provides a reliable initialization point for the optimization of the process has been applied with success to different synthesis. The production of methyl-tert-butyl-ether (MTBE) and methyl acetate are presented as examples

    On the integration of reaction and separation in a batch extractive distillation column with a middle vessel

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    In this work, the integration of reaction and separation in a batch extractive distillation column with a middle vessel/reactor is analyzed for azeotrope-forming mixtures. This equipment configuration has the potential to promote the complete conversion of reactants; therefore, the main process characteristics are investigated. A mixture showing several azeotropes and involving an esterification reaction was selected as an academic example. The first part of the paper deals with the phase-equilibrium analysis of the mixture. The nodes (pure components and azeotropes) and the distillation regions of the multicomponent mixture are obtained. The analysis of the topology of the residue-curve map is used to select one of the reagents as entrainer. Feasibility of the combined operation is studied based on the phase-equilibrium analysis and the investigation of the feasible cuts at infinite separation power. The second part of the contribution focuses on the different steps of the process. The influence of operating and process parameters on the operation performance is studied with the aid of a process simulator. Physical explanations are given for the results. Results show the advantages of integrating reaction and separation to enhance both reagents conversion and product separation.Fil: Espinosa, Hector Jose Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo y Diseño. Universidad Tecnológica Nacional. Facultad Regional Santa Fe. Instituto de Desarrollo y Diseño; Argentin

    VISUALIZATION METHODS FOR EVALUATION OF FEASIBLE SEPARATIONS OF AZEOTROPIC MIXTURES

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    In this study the visualization system AVS (Application Visualization System) is applied. This tool is provided with a module library for userfriendly modelling of systems under study. Three data viewers are implemented: Image Viewer, Graph Viewer and Geometry Viewer allowing the graphical representation of multidimensional data fields as the boiling and dew temperatures as a function of the composition. By using special modules the graphical representations can be characterized by colours, brightness and other effects; by the zoom module the scale can be varied; there are also possibilities for the animation of the objects under study, the representation of isolines, for example of temperature or driving forces, as well as the calculation and representation of vector fields. The last option makes it possible to construct representation combining information about the residue curve map and the temperature surface

    Development of a robust algorithm to compute reactive azeotropes

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    In this paper, a novel approach for establishing the route for process intensification through the application of two developed softwares to characterize reactive mixtures is presented. A robust algorithm was developed to build up reactive phase diagrams and to predict the existence and the location of reactive azeotropes. The proposed algorithm does not depend on initial estimates and is able to compute all reactive azeotropes present in the mixture. It also allows verifying if there are no azeotropes, which are the major troubles in this kind of programming. An additional software was developed in order to calculate reactive residue curve maps. Results obtained with the developed program were compared with-the. published in the literature for several mixtures, showing the efficiency and robustness of the developed softwares.23339540

    Extractive distillation: recent advances in operation strategies

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    Extractive distillation is one of the efficient techniques for separating azeotropic and low-relativevolatility mixtures in various chemical industries. This paper first provides an overview of thermodynamic insight covering residue curve map analysis, the application of univolatility and unidistribution curves, and thermodynamic feasibility study. The pinch-point analysis method combining bifurcation shortcut presents another branch of study, and several achievements have been realized by the identification of possible product cut under the following key parameters: reflux ratio, reboil ratio, and entrainer-feed flow rate ratio. Process operation policies and strategy concerning batch extractive distillation processes are summarized in four operation steps. Several configurations and technological alternatives can be used when extractive distillation processes take place in a continuous or batch column, depending on the strategy selected for the recycle streams and for the main azeotropic feeds

    A systematic framework for assessing the applicability of reactive distillation for quaternary mixtures using a mapping method

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    Reactive distillation (RD) is a useful process intensification technique used in the chemical process industries as it offers important advantages such as energy and cost savings, relative to conventional technologies. However, industrial application of RD is still limited by the complexity of designing and understanding such a complex process. While simple, robust shortcut design methods that require only basic information (such as the relative volatility of components) exist for conventional distillation, such methods for evaluating the applicability of RD are not yet established. This work fills this gap by presenting a new systematic framework for assessing the RD applicability based on a mapping method. The method enables RD designs to be screened using only relative volatilities and chemical equilibrium constant as input data. The evaluation focuses on reactions involving four components (A + B ⇌ C + D) with various boiling point orders, which are of most industrial importance. The proposed systematic framework is validated through its application to five case studies, (trans-)esterifications presenting various separation challenges due to the formation of azeotropes. This novel approach offers a valuable aid for engineers in taking an educated go/no-go decision in the very initial stages of conceptual design, before performing any rigorous simulations of RD flowsheets
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