基于MATLAB的双液系汽液平衡模型构建及其相图绘制

汽液相平衡数据的测量及热力学模型的研究是化学工程中的重要内容之一。本文借助MATLAB软件计算平台,将在乙醇-环已烷互溶双液系中测定的汽液相平衡实验数据,代入选定的汽液相平衡数学模型Wilson方程,通过程序设计自动完成该关联方程的最小二乘求解,得到其配偶参数;随后,借由回归的Wilson方程计算各实验观测点汽相组成的热力学模型预测值,并与实验值协同统计学方法执行热力学一致性检验。应用结果表明构建的Wilson汽液相平衡模型通过热力学一致性检验,且恒沸点温度及组成数据的预测精度高,整个MATLAB操作过程直观、方便与快捷,绘制的相图美观,符合实验要求。     

碳酸二乙酯-草酸二乙酯二元体系汽液平衡数据的测定与关联

测定了碳酸二乙酯草酸二乙酯二元体系常压汽液平衡数据，利用二元体系的汽液平衡实验数据，运用Visual Basic计算机语言，采用EOS γ法分别用Wilson和NRTL方程模拟计算了碳酸二乙酯-草酸二乙酯二元体系在常压下的汽液平衡并进行了关联，其平均偏差分别为0．0309和0．0201，并进行了热力学一致性检验，两种不同模型的计算结果与实验值都较为吻合，其中以NRTL拟合结果为更好。     

UNIFAC-SRK模型应用范围的进一步拓展

根据HV混合规则,利用UNIFAC模型、SRK状态方程及相关热力学函数,推导出UNIFAC-SRK模型的逸度系数方程。根据Nelder-Meand法,采用FORTRAN编程,估算出了18对新的基团交互作用参数,扩大了该模型的应用范围。根据估算出的基团参数对35个二元汽液平衡体系的泡点压力和汽相组成进行了预测,预测值和实验值吻合良好。     

丁酮-醋酸异丙烯酯等压汽液平衡数据的测定和关联

为了给醋酸异丙烯酯异构化制乙酰丙酮工艺的产物分离提供基础热力学数据,用改进的埃利斯(Ellis)平衡蒸馏器测定了常压下丁酮-醋酸异丙烯酯体系的汽液平衡数据。结果表明,实验数据经Herington面积法热力学一致性检验。采用活度模型Wilson方程和NRTL方程对实验数据进行了关联,计算结果与实验数据均较为吻合。同时关联得到了两方程的模型参数,可满足工程设计的需要。     

甲酸-水-N-甲基吡咯烷酮体系等压汽液平衡的研究

在常压下测试甲酸-水、甲酸-N-甲基吡咯烷酮、水-甲酸-N-甲基吡咯烷酮的汽液平衡数据。考虑甲酸在汽相中的缔合效应,用维里方程和Hayden-O'connell关联式修正了汽相的非理想性,并用非线性最小二乘法关联前2对二元体系的汽液平衡数据,得NRTL和Wilson方程的模型参数。以NRTL模型参数预测三元体系汽液平衡数据,温度平均偏差为1.76℃,甲酸的汽相平均偏差为0.032 2,水的汽相平均偏差为0.040 4;以Wilson模型参数预测三元体系汽液平衡数据,温度平均偏差为1.66℃,甲酸的汽相平均偏差为0.027 5,水的汽相平均偏差0.011 6,可见2个模型预测值均与实验值吻合良好,而Wilson模型的关联精度较高。     

二甲醚-甲醇二元体系汽液平衡的测定与计算

在0～1.45MPa压力范围内,测定了293．15K、323．15K、353．15K、373．15K温度下二甲醚-甲醇二元体系的汽液相平衡数据。利用气相色谱检测汽液相组成,对测定数据进行了热力学计算,采用PR方程计算气相各组分的逸度系数,利用NRTL和UNIFAC法计算液相活度系数。两种不同模型计算值与实验值符合良好,汽液相平衡数据经Herington面积法校验满足热力学一致性检验。     

常压下丙醛-水-甘油体系汽液平衡测定与关联

采用单循环汽液平衡釜测定了常压条件下丙醛-水的二元以及丙醛-水-甘油三元汽液平衡数据。运用MATLAB中求解非线性最小二乘法问题的函数Lsqnonli,结合丙醛-水的二元汽液平衡实验据,迭代出了Margules、Vanlaar、Wilson和UNIQAC四个方程的二元模型参数。通过计算值和实验值的比较,Wilson方程的相对误差均小于5%,故选择Wilson方程为本体系的适合模型。将测定的丙醛-水-甘油三元汽液平衡数据与模型参数带入Wilson方程求得的三元汽液平衡数据相比较,相对误差均小于5%,由此验证了本文Wilson模型参数的可靠性。本文的测定结果和计算结果为丙醛-水-甘油体系的萃取精馏模拟选择了合适的模型,关联得到的Wilson模型参数,为萃取精馏过程的模拟计算打下基础,同时也为丙醛和水混合液的有效分离提供了一定基础数据。     

101.33kPa下N-甲基乙酰胺+醋酸+水汽液相平衡研究

用改进式Rose釜测定了101.33kPa下N-甲基乙酰胺 醋酸二元体系和N-甲基乙酰胺 醋酸 水三元体系的汽液平衡数据。对N-甲基乙酰胺 醋酸体系VLE数据进行了面积法热力学一致性检验,用NRTL、Wilson、UNIQUAC模型关联得到了相应的模型参数。最后用二元体系的NRTL模型参数推算了所测N-甲基乙酰胺 醋酸 水三元体系的汽液平衡数据。推算结果中,温度的平均偏差为0.94℃,水在汽相中的平均偏差为0.0137。     

乙酸乙酯-乙醇-水与甘油体系的液液平衡数据测定及关联

液液平衡数据的测定及热力学模型的研究是化学工程中的重要内容之一,虽然目前已有大量的液液平衡数据发表,但仍有很多物系的相平衡数据有待于人们来测定和研究.本研究选取甘油作为乙酸乙酯液液萃取分离的萃取剂.采用色谱法测定乙醇在甘油中的无限稀释活度系数,并采用单参数法关联UMQUAC方程中的模型参数;采用液液平衡釜测定乙酸乙酯-水、乙酸乙酯-甘油二元体系和乙酸乙酯-乙醇-甘油、乙酸乙酯-水-甘油、乙酸乙酯-乙醇-水三元体系LLE数据,采用最小方差法关联UNIQUAC方程中的模犁参数,并关联二元及三元LLE数据;利用六对模型参数模拟四元LLE数据,并与实验值相比较,实验与计算误差均小于5%.实验值与模拟值吻合较好,精度满足要求,从而可以为液液萃取的工艺改进模拟计算提供可靠的热力学基础数据.另外该体系的液液相平衡数据对于乙酸乙酯的提纯有实际的应用价值.     

低压下甲苯二胺同分异构体的气液平衡及应用

采用汽液双循环法测定甲苯二胺(TDA)间位和邻位同分异构体在低压下(50 mmHg和100 mmHg)的VLE数据,用热力学一致性检验所测得的数据进行,用Wilson热力学回归了模型的二元交互作用参数。将该模型用于TDA同分异构体分离塔的模拟计算中,结果与生产数据基本相吻合,表明所得的TDA同分异构体的气液平衡关系以及由此建立的热力学模型在工业生产中确是实用有效的,可用于实际的工业生产中。     

NH3—CO2—H2O体系的相平衡计算及图形输出

针对含化学反应的ＮＨ３－ＣＯ２－Ｈ２Ｏ弱电解质体系的复杂相平衡计算问题，以Ｅｄｗａｒｄｓ（１９７８）的模型为基础，采用液相内的化学平衡与汽液相平衡分计计算的思想，成功地编制了在较宽的温度和压力范围内的计算机程序，除了可用于实工业生产的模拟计算，还设计了图形输出块，通过计算机自动绘制汽液平衡相图，可直接与实验结果进行比较。     

Experimental investigation and modeling of vapor-liquid equilibria for Bi–Zn and Bi–Sn–Zn systems at 10 Pa

For the Bi–Zn and Bi–Sn–Zn systems, vacuum distillation experiments were carried out at 10 Pa. The results show that the content of Zn for the Bi–Zn system in the vapor phase could reach more than 0.999 mol fraction in vacuum distillation. The VLE (vapor-liquid equilibrium) data were correlated using the Tsuboka-Katayama's modification of the Wilson equation (T-K-Wilson). The correlation showed good agreement with experimental data. Thermodynamic consistency tests of experimental data for the binary and ternary systems were presented by the Van Ness method. The results demonstrate that VLE phase diagram is reliable for predicting the process of vacuum distillation for the systems. It provides an efficient way to guide the separation and purification of crude Zn in vacuum metallurgy     

乙酸乙酯-乙醇-水-甘油体系中三元及四元体系的汽液平衡数据测定及推算

设计了液液平衡釜,测定乙酸乙酯-乙醇-甘油、乙酸乙酯-水-甘油及乙醇-水-甘油三元体系的VLE数据;以Wilson方程为平衡模型,由两对二元模型和三元体系的VLE实验数据关联第三对模型参数;测定乙酸乙酯-乙醇-水-甘油体系的VLE数据,由二元模型参数及三元体系的VLE实验数据计算乙酸乙酯-乙醇-水-甘油体系的VLE数据并与实验数据比较;本文测定结果及计算结果为乙酸乙酯-乙醇-水、乙酸乙酯-乙醇体系的萃取分离模拟计算及试验提供基础数据。     

Genetic programming based models for prediction of vapor-liquid equilibrium

The design, operation, and control of chemical separation processes heavily rely on the knowledge of the vapor-liquid equilibrium (VLE). Often, conducting experiments to gain an insight into the separation behavior becomes tedious and expensive. Thus, standard thermodynamic models are used in the VLE prediction. Sometimes, exclusively data-driven models are also used in VLE prediction although this method too possesses drawbacks such as a trial and error approach in specifying the data-fitting function. For overcoming these difficulties, this paper employs a machine learning (ML) formalism namely “genetic programming (GP)” possessing certain attractive features for the VLE prediction. Specifically, three case studies have been performed wherein GP-based models have been developed using experimental data, for predicting the vapor phase composition of a ternary, and a group of non–ideal binary systems. The inputs to models consists of three pure component attributes (acentric factor, critical temperature, and critical pressure), and as many intensive thermodynamic parameters (liquid phase composition, pressure, and temperature). A comparison of the VLE prediction and generalization performance of the GP-based models with the corresponding standard thermodynamic models reveals that the former class of models possess either superior or closely comparable performance vis-a-vis thermodynamic models. Noteworthy features of this study are: (i) a single GP-based model can predict VLE of a group of binary systems, and (ii) applicability of a GP-based model trained on an alcohol-acetate series data for its higher homolog. The VLE modeling approach exemplified here can be gainfully extended to other ternary and non-ideal binary systems, and for designing corresponding experiments in different pressure and temperature ranges.     

甲基三氯硅烷-二甲基二氯硅烷-苯体系中二元体系的汽液平衡数据推算

在预测卤化硅烷体系性能时,通过改变溶液的混合规则来确定预测方案。估算了甲基三氯硅烷、二甲基二氯硅烷、苯相互之间组成的二元体系在恒压101.325 kPa下的相互作用参数,这种估算是基于把汽相看成理想溶液来实现的,而且采用matlab优化工具箱中的非线性最小二乘法用Wison模型关联了实验数据,预测结果比文献更逼近实验数据。这些二元体系汽液平衡数据为卤硅烷的生产提供了理论依据。     

Assessment of numerical optimization algorithms for the development of molecular models

In the pursuit to study the parameterization problem of molecular models with a broad perspective, this paper is focused on an isolated aspect: It is investigated, by which algorithms parameters can be best optimized simultaneously to different types of target data (experimental or theoretical) over a range of temperatures with the lowest number of iteration steps. As an example, nitrogen is regarded, where the intermolecular interactions are well described by the quadrupolar two-center Lennard-Jones model that has four state-independent parameters. The target data comprise experimental values for saturated liquid density, enthalpy of vaporization, and vapor pressure. For the purpose of testing algorithms, molecular simulations are entirely replaced by fit functions of vapor-liquid equilibrium (VLE) properties from the literature to assess efficiently the diverse numerical optimization algorithms investigated, being state-of-the-art gradient-based methods with very good convergency qualities. Additionally, artificial noise was superimposed onto the VLE fit results to evaluate the numerical optimization algorithms so that the calculation of molecular simulation data was mimicked. Large differences in the behavior of the individual optimization algorithms are found and some are identified to be capable to handle noisy function values.     

碳酸二甲酯—甲醇二元体系汽液平衡数据的推算与关联

利用共沸点数据,分别用Wilson,NRTL和UNIFAC方程模拟计算了碳酸二甲酯－甲醇二元体系在常压下的汽液平衡,3种不同模型的计算结果与实验值都较为吻合,其中以UNIFAC方程的拟合结果为最好。