Design and control of pressure-swing distillation for separating ternary systems with three binary minimum azeotropes

The separation of ternary nonideal systems with multi-azeotrope is very important because they are often found in the waste of chemical and pharmaceutical industries, which is much more difficult due to the formation of multi-azeotrope and distillation boundary. We propose a systematic procedure for design and control of a triple-column pressure-swing distillation for separating ternary systems with three binary minimum azeotropes. This procedure involves thermodynamic insights, a two-step optimization method, and effective control strategy. The separation of tetrahydrofuran (THF)/ethanol/water is used to illustrate the capability of the proposed procedure. It is found that the pressure limits in columns can be determined through the analysis of residue curve maps, distillation boundary, and isovolatility curves. The optimal triple-column pressure-swing distillation is generated with the minimum total annual cost (TAC) of $2.181 × 10⁶ in sequence A. The operating conditions are well controlled approaching their desired specifications in an acceptable time when disturbances occur. © 2019 American Institute of Chemical Engineers AIChE J, 65: 1281–1293, 2019     

Statistical analysis of the kinds of vapor-liquid equilibrium diagrams of three-component systems with binary and ternary azeotropes

The kinds of K-ordered region diagrams have been established for 3962 three-component systems containing only binary azeotropes and for 402 three-component systems containing ternary azeotropes. The number of diagrams of each kind and the number of kinds having common features have been determined. The diagrams have been analyzed statistically in terms of their types, the number and kinds of azeotropes, and types of singular points.     

Determination of concentration regions of existence of ternary azeotropes: Systems showing mixed deviations from ideal behavior

Regions of possible existence of ternary azeotropes are located in three-component systems whose binary liquid phases show mixed deviations from ideal behavior.     

Determination of concentration regions of existence of ternary azeotropes: 1. Systems showing like deviations from ideal behavior

The regions of possible ternary azeotropes can be determined by analysis of the concentration dependences of activity coefficient complexes at infinite dilution, which reflect the deviations of the phases from the Raoult—Dalton law. The case of like deviations of the binary constituents from this law is considered.Translated from Teoreticheskie Osnovy Khimicheskoi Tekhnologii, Vol. 38, No. 6, 2004, pp. 683–692.Original Russian Text Copyright © 2004 by Raeva, Serafimov.     

Determination of concentration regions of existence of ternary azeotropes: II. Systems showing unlike deviations from ideal behavior

Regions of the possible existence of ternary azeotropes in systems showing unlike deviations of binary constituents from the Raoult-Dalton law are revealed by analyzing the concentration dependence of complexes of the activity coefficients at infinite dilution.     

预测共沸物的同伦-牛顿联合方法

为了更有效地预测共沸系统,文内提出了同伦-牛顿联合算法,首先利用具有全局收敛性的同伦算法产生较好的初值,然后利用收敛速度快的牛顿算法求解共沸方程。应用联合方法预测了多个二元和三元非理想性物系的共沸点,结果表明,同伦-牛顿联合方法有较大的收敛范围,较高的迭代过程稳定性,较快的收敛速度。     

三元互溶混合液体闪点预测研究

闪点是评价易燃液体火灾危险性重要指标。文中基于定量结构-性质相关性(QSPR)原理对三元互溶混合液体的闪点与其结构信息间的内在定量关系(M-QSPR)开展了理论研究。从结构信息角度计算混合物描述符,并采用Kay's mixing rule混合规则对混合液体的结构特征进行表征,应用遗传-多元线性回归(GA-MLR)算法,优化筛选出与混合体系闪点最密切的结构参数作为输入参数,分别采用多元线性回归(MLR)和支持向量机(SVM)算法建立三元互溶混合液体闪点的理论预测模型,并将其与文献已有模型比较。研究结果表明:预测模型不仅有较好的预测能力,还可揭示影响三元互溶混合液体闪点的主要结构因素及其影响规律。     

Prediction of equilibrium liquid compositions from dew-point measurements for ternary systems

A simple calculation procedure is developed which permits the prediction of bubble-point compositions from dew-point measurements for ternary systems at low pressures.The proposed method is equally applicable to isothermal and isobaric data. It does not require any calculation of liquid activity coefficients and their correlation by means of an integrated Gibbs-Dubem equation, nor does it require any supporting physical properties of the pure components constituting the ternary system.Calculation of the bubble-point compositions from the dew-point data for the ternary system methyl ethyl ketone-n-heptane-toluene at 760 torr is carried out to serve as an illustration of the proposed method.     

Prediction of ternary liquid-liquid equilibria using the NRTL and the UNIQUAC models

The Experimental binodal curve, tie line data, plait point data and the tie lines and plit point, calculated by liquid models for foil wing six ternary liquid liquid equilibria systems: monochlorobenzene-water-acetone, cyclohexane-water-acetone, cyclohexane-water-acetone. chlorform-water-acetone. methylisobutylketone-water-acetone, and n-hexane-water-acetone were reported at 10°C Experimental tie line data were correlated to test consistency with Othmer-Tobias equation [15] And those data were also correlated with the NRTL the UNIQUAC, and the modified UNIQLAC models respectively and the parameters in each model were estimated to predict the value of tie lines by least squares methods.     

三元可燃性液体水溶液闪点的理论预测

为了预测三元互溶可燃性液体水溶液的闪点,分析确定了影响混合溶液闪点的主要因素,如沸点、相对分子质量、相对密度、饱和蒸汽压、表面张力等。将这些因素作为输入变量,应用支持向量机算法对混合溶液闪点与其对应理化参数之间的内在定量相关性进行了研究,建立了三元互溶可燃性液体水溶液闪点的理论预测模型。对预测模型进行了验证,讨论了模型的有效性和可靠性;解释了模型反映的机制,明确了混合溶液闪点的主要影响因素及其重要程度。     

Dynamic behaviour of side-stream distillation columns for the separation of binary azeotropes mixtures

In the last years, the interest for dynamic modelling and simulation has increased. However, the studies have been restricted to two-column products. A side-stream distillation column may replace two simple columns for some applications, saving energy and investment. Intuitively, the side-stream should primarily contain middle-boiling point from a multicomponent mixture. Using the residue curves, we can define new separation sequences and new configurations for old processes. The principal proposal of this work is to analyse the dynamic behaviour of side-stream extractive distillation column, a new configuration for extractive distillation process, and to compare it with the conventional one used for the same objective. It is observed that the dynamic behaviour of side-stream column is very fast and the operating performance of the column is nearly the same of the conventional one.     

Batch extractive distillation as a hybrid process: separation of minimum boiling azeotropes

The batch extractive distillation is compared with the hybrid process (absorption+distillation) by feasibility studies and rigorous simulation. A new method is presented for the assessment of feasibility of the hybrid batch extractive distillation. The limiting values of the operational parameters are determined. Calculations are presented for the separation of the minimum boiling azeotropic mixtures of acetone-methanol and ethanol-water by the application of water and ethylene glycol as heavy solvents, respectively.     

UNIFAC模型与PRSV方程相结合预测二元及三元系统汽液相平衡

采用Ｗｏｎｇ和Ｓａｎｄｌｅｒ混合规则，将ＰＲＳＶ立方型状态方程与ＵＮＩＦＡＣ活度系数模型相结合，给出一种预测混合物相平衡热力学性质的方法，并用５４个二元体系和９个三元体系的实验数据做了检验，结果表明，该法可以较好地预测二元及三元体系的汽液相平衡。     

Systematic design of an extractive distillation for maximum‐boiling azeotropes with heavy entrainers

Extractive distillation is one of the most attractive approaches for separating azeotropic mixtures. Few contributions have been reported to design an extractive distillation for separating maximum‐boiling azeotropes and no systematic approaches for entrainer screening have been presented. A systematic approach to design of two‐column extractive distillation for separating azeotropes with heavy entrainers has been proposed. A thermodynamic feasibility analysis for azeotropes with potential heavy entrainers was first conducted. Then, five important properties are selected for entrainer evaluation. Fuzzy logic and develop membership functions to calculate attribute values of selected properties have been used. An overall indicator for entrainer evaluation is proposed and a ranking list is generated. Finally, the top five entrainers from the ranking list have been selected and use process optimization techniques to further evaluate selected entrainers and generate an optimal design. The capability of the proposed method is illustrated using the separation of acetone–chloroform azeotropes with five potential entrainers. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3898–3910, 2015     

PP/POE/PA6三元共混物相形态的预测及受混炼顺序的影响

引言对聚合物进行共混是改善其性能的重要方法,多元聚合物共混物结合了多种聚合物的优点,具有更多独特的性能,因此对多元尤其是三元共混物的研究越来越多[1-5]。聚合物共混物的相形态对其性能有着决定性的影响[6-9],因而相形态是共混物研究的一个非常重要的方面[9-12]。     

带共沸的乙醇/乙酸乙酯/2-丁酮三元物系变压精馏分离过程及其参数优化

提出了一种带两股循环的三塔变压精馏结构用于分离乙醇（C₂H₅OH）/乙酸乙酯（C₄H₈O₂-3）/2-丁酮（C₄H₈O-3）三元混合物。由该三元混合物的剩余曲线图（RCM）可知,在大气压下该混合物的每一对组元均形成二元最低共沸物,且乙醇/乙酸乙酯二元共沸物组成随压力变化敏感。三个最低共沸物的同时存在形成了精馏边界线夹紧点现象,而通常压力下的精馏塔无法跨越,以至于传统变压精馏无法应用。通过对精馏塔压力的最优化克服了这一困难,提出了新的分离流程,并对过程进行严格稳态模拟。针对初分塔（T1）塔压不同的6种流程,采用序贯迭代法对各塔的塔板数、进料板位置、回流比等参数进行了优化。通过对比6种流程的经济评价和比较,得到了T1塔的最优压力,并经过能量集成使得过程的年度总费用降低了14.88%。     

Reliable computation of binary homogeneous azeotropes of multi-component mixtures at higher pressures through equation of states

A method to compute binary homogeneous azeotropes in multi-component mixtures at elevated pressures through the equation of state approach is developed. The method is capable of predicting the homogeneous azeotropes and is in close agreement with experimental data. At higher pressures, vapor and liquid phase non-idealities are incorporated using vapor and liquid phase fugacity coefficients from Peng-Robinson-Stryjek-Vera equation of state with Wong-Sandler mixing rules. The method is also capable of predicting the exact value of bifurcation pressure where homogeneous azeotropes may appear or disappear. The method can predict the azeotropes at elevated pressures and is independent of equation of state and mixing rules. The method is also capable of predicting the double azeotropy in binary mixtures. The method is tested with Ethanol-Water, Isopropanol-Water, Carbon dioxide-Ethane-Ethylene and Ammonia-R-125 systems. The highly non-linear system of equations is solved by homotopy continuation approach.