四种活度系数模型在汽-液平衡和精馏计算中的应用和比较

作者将最近十余年来发展的四种活度系数模型（Wilson、NRTL、McCann和UNIFAC）与维里方程及三对角矩阵法相结合,成功地应用于各类非理想溶液精馏过程的严格计算。所编的NIDISTL精馏计算程序曾先后对33个精馏系统进行过百余次考核运算。 为对这些活度系数模型作一平行的比较,本文选取了18组二元汽-液平衡实验数据,用非线性最小二乘法分别确定Wilson、NRTL和McCann方程中各对二元参数值。所得参数值被应用于预测18组二元系和8组由此导出的多元系泡点汽-液平衡数据,并与UNIFAC官能团模型的预测结果及实验数据作比较。 通过四个精馏计算的示例,可以说明采用下同活度系数模型时的收敛特性和计算结果是一致的。本文对各模型所算得的温度、流量和组成分布作了比较,并就某些情况下可能出现较大偏离的原因进行了讨论。     

聚甲醛二甲醚体系汽液平衡数据的测定与关联

通过改进的Rose汽液平衡釜在常压条件下测定了PODE₂-PODE₃二元体系的汽液平衡数据,对所测得的实验数据进行热力学一致性检验,结果表明所测汽液平衡可通过热力学一致性检验。使用Aspen Plus v8.8 模拟软件,分别对NRTL、Wilson、UNIQUAC活度系数模型进行关联,通过回归得到对应的二元交互作用参数,并将三种模型拟合所得到的汽液平衡数据与实验所得的数据相对比,得到拟合值与实验值的温度和气相组成的平均绝对偏差均不大于0.37 K和0.0044,表明3种模型的拟合结果与实验数据吻合均较好,偏差均在合理范围内。这些工作为化工数据库增添了精馏的基础数据,也为含PODE₂和PODE₃体系的精馏设计与工程设计的进一步深入研究奠定了基础。     

The Distillation Process Design for the Ternary System 1,2-Butanediol + 1,4-Butanediol + 2,3-Butanediol

The isobaric vapor-liquid equilibrium data for distillation have been measured for three binary systems of (1,2-butanediol(BD)+1,4-BD), (1,2-BD+2,3-BD), and (1,4-BD+2,3-BD) and for the ternary system of (1,2+BD+1,4-BD+2,3-BD) at 101.3 kPa. The thermodynamic properties of the vapor phase have been calculated with the Hayden-O’Connell equation in consideration of nonideality. The liquid activity coefficients have been satisfactorily correlated with the Wilson, NRTL and UNIQUAC models. The corresponding binary interaction parameters of the three models were calculated. Based on all the preceding results, a two-column distillation process was designed to obtain the required products with purity of 98% for industrial use.     

丙酮-异丙醇-甲基烯丙醇体系气液平衡数据测定及关联

采用双循环气液平衡釜,测定了常压(101.3 kPa)下丙酮-甲基烯丙醇和异丙醇-甲基烯丙醇二元体系以及部分丙酮-异丙醇-甲基烯丙醇三元体系的气液平衡数据。二元气液平衡数据经Herington面积检验法检验,符合热力学一致性。用Wilson和NRTL液相活度系数方程对两个二元体系的气液平衡数据进行关联,效果良好。由关联得到的两个二元体系的Wilson和NRTL模型参数,及Aspen Plus数据库中的丙酮-异丙醇体系的Wilson和NRTL模型参数预示部分三元体系的气液平衡数据,与实验值相比,丙酮、异丙醇和甲基烯丙醇气相摩尔分率平均绝对偏差分别小于0.0137、0.0113、0.0117。实验数据和关联结果为该三元体系的精馏分离提供了一定的基础数据。     

二乙氧基甲烷-乙醇-水-甘油体系部分组分液液平衡

用液液平衡釜测定了二乙氧基甲烷-水、二乙氧基甲烷-甘油2组二元和二乙氧基甲烷-水-甘油、二乙氧基甲烷-乙醇-甘油、二乙氧基甲烷-水-乙醇3组三元体系常温、常压下的液液平衡数据。用NRTL和UNIQUAC方程对所测二元体系的平衡数据进行了处理。采用单参数法关联了乙醇-甘油体系的模型参数。结合三元体系的液液平衡数据,用NRTL和UNIQUAC方程关联出了三元体系中的第3对模型参数。确定了二乙氧基甲烷-乙醇-水-甘油体系合适的模型及参数,为含二乙氧基甲烷体系的实际分离过程提供了依据。     

水-乙酸-乙酸丁酯体系汽液平衡研究

用改进Rose釜测定了乙酸-乙酸丁酯、水-乙酸-乙酸丁酯(完全互溶区)体系在101.33 kPa下的汽液平衡数据。考虑乙酸的缔合效应,利用维里方程和Hayden-O'Connell(HOC)模型计算各组分的汽相逸度系数,校正汽相的非理想性,液相的非理想性全部归结到液相活度系数中予以校正。用NRTL,UNIQUAC模型对乙酸-乙酸丁酯的汽液平衡数据进行关联,并得到相应的模型参数、温度偏差和汽相组成偏差。比较二元体系的关联结果,用NRTL模型参数预测了三元汽液平衡数据,计算值与实验值吻合良好,预测精度较好,说明采用的模型参数是可靠的,能够为精馏的设计和模拟计算提供基础热力学数据。     

基于离子液体的合成氨驰放气中氨回收工艺模拟计算

设计并模拟优化了以[C4mim]BF4离子液体为吸收剂的吸收与多级闪蒸回收氨的工艺,采用NRTL活度系数模型对氨和甲烷在[C4mim]BF4中的气液平衡数据进行拟合,结果表明,该模型能很好地关联和预测含离子液体的二元体系气液平衡. 应用Aspen Plus软件灵敏度分析模块,对吸收剂流量、温度进行了灵敏度分析和优化,结果表明,增大流量和降低温度有利于[C4mim]BF4对氨的吸收,优化操作条件为流量2000 kg/h、温度30℃. 该回收工艺净化气和再生气中氨摩尔浓度分别为32.4′10-6和95.2%,满足设计要求,标准煤耗预计为940 kg/t,比传统工艺节能200 kg/t.     

用于描述三元水醇系统汽液平衡的活度系数模型

In this study, three semipredictive activity coefficient models: Wilson, non-random-two liquid model (NRTL), and universal quasi-chemical model (UNIQUAC), have been used for modeling vapor-liquid equilibrium properties of ternary mixtures that include substances found in alcoholic distillation processes of wine and musts. In particular, vapor-liquid equilibrium in ternary mixtures containing water + ethanol + congener has been modeled using parameters obtained from binary and ternary mixture data. The congeners are substances that although present in very low concentrations, of the order of part per million, are important enological parameters. The results given by these different models have been compared with literature data and conclusions about the accuracy of the models studied are drawn, recommending the best models for correlating and predicting phase equilibrium properties of this type of mixtures.     

丙酮-水-丙酮连氮体系汽液平衡测定与关联

采用汽液双循环平衡釜,在常压（101.3 kPa）下测定了丙酮-丙酮连氮二元组分物系以及部分丙酮-水-丙酮连氮三元组分物系的汽液平衡数据。实验数据经Herington面积积分法检验符合热力学一致性。通过化工过程模拟软件,分别采用Wilson、NRTL、UNIQUAC 活度系数模型对丙酮-丙酮连氮二元组分物系实验数据进行关联得到模型参数。并对汽液平衡的计算值与实验值进行比较,3种模型都吻合良好,其中由NRTL方程关联得到的计算结果最为适合,平均温度偏差和汽相组成偏差分别为0.0639 K和0.0048。从三元汽液相平衡数据中拟合出了丙酮-丙酮连氮、丙酮-水、水-丙酮连氮之间的NRTL方程相互作用参数。为验证数据及其二元相互作用参数的可靠性,利用关联出的丙酮-丙酮连氮模型参数计算出汽相组成与丙酮-丙酮连氮的二元数据比较,二者符合较好。实验和关联的结果为精馏分离丙酮-水-丙酮连氮汽液平衡体系提供了一定的基础数据。     

乙酸异戊酯+异戊醇和乙酸异戊酯+正己醇体系汽液平衡

在50.00和101.33 kPa下,采用改进的Rose汽液平衡釜测量乙酸异戊酯+异戊醇和乙酸异戊酯+正己醇体系的汽液平衡数据。乙酸异戊酯+异戊醇在50.00 kPa下形成最低共沸物。使用Herington法对汽液平衡数据进行热力学一次性检验,结果表明测得的汽液平衡数据符合热力学一致性。对实验数据使用NRTL、Wilson和UNIQUAC活度系数模型进行关联,回归获得相应的二元交互参数,模型计算的温度和组成与实验值相比均方差小于0.20 K和0.0050,表明3种模型的拟合结果与实验数据吻合较好。通过Wilson模型预测乙酸异戊酯+异戊醇体系在98.4 kPa时共沸点消失。为化工数据库增添了内容,为乙酸异戊酯体系的工程设计和进一步深入研究奠定了基础。     

N-甲酰吗啉与苯的二元等压汽液平衡

石化系统、焦化行业,采用N-甲酰吗啉（NFM）溶剂精制芳烃受到极大重视,但可资利用的基础数据却极为贫乏,尚无等压汽液平衡数据。用改进的EC-2型汽液平衡釜,测定了常压下苯-NFM、甲苯-NFM二元体系汽液平衡数据,并用 NRTL 和 UNIQUAC 模型对实验数据进行了关联,得到了模型相应的二元交互参数。经Herington 面积法检验,上述数据满足热力学一致性要求,结果较为满意。研究结果填补了该项数据空白,完全能满足N-甲酰吗啉溶剂精制芳烃工程设计的需要。     

CALCULATION OF THE BINARY INTERACTION AND NONRANDOMNESS PARAMETERS OF NRTL,NRTL1, AND NRTL2 MODELS USING GENETIC ALGORITHM FOR TERNARY IONIC LIQUID SYSTEMS

One of the most important applications of thermodynamics is the accurate prediction of fluid phase equilibria problems related to real chemical engineering processes. Various equations of state as well as activity coefficient models have been developed for such calculations with many interaction, size, and randomness parameters, which should be optimized based on powerful and effective computational methods. Leading to globally optimal values, genetic algorithm (GA) as a powerful and effective tool can be used for prediction of the interaction parameters of thermodynamic models in complex liquid-liquid equilibrium (LLE) systems. It requires only lower and upper bounds for the interaction parameters and the necessary initial guesses are produced automatically. In the present work, based on the GA method, a global optimization procedure is introduced for calculation of the binary interaction and nonrandomness parameters of NRTL, NRTL1, and NRTL2 activity coefficient models for 20 ternary aromatic extraction systems containing 16 different ionic liquids at various temperatures. The values of the parameters along with the root-mean-square deviations (rmsd) are reported. The results, in terms of rmsd for NRTL, NRTL1, and NRTL2 models, are very satisfactory, with global values of 0.0031, 0.0020, and 0.0053 for 187 tie-lines respectively. The obtained rmsd values for the NRTL model using the GA method are better than those reported in the literature. The rmsd results for the three studied models show that NRTL1 can handle the LLE calculations with more accuracy than the original NRTL and NRTL2 activity coefficient models.     

Thermodynamic modeling of vapor-liquid equilibrium of binary systems ionic liquid + supercritical {CO2 or CHF3} and ionic liquid + hydrocarbons using Peng-Robinson equation of state

Vapor-liquid equilibrium (VLE) data from literature for binary systems involving several ionic liquids were correlated. The Peng-Robinson equation of state, coupled with the van der Waals and Wong-Sandler mixing rules, was used as the thermodynamic model to evaluate the fugacity coefficients. The UNIQUAC and NRTL models were used to calculate the excess Gibbs free energy in the Wong-Sandler mixing rule. A molecular modeling strategy using the software ChemOffice was used to calculate the volume and surface area parameters of ionic liquids for UNIQUAC, while the binary interaction energy parameters for UNIQUAC and NRTL models, as well as the binary interaction parameter of the van der Waals and Wong-Sandler mixing rules were estimated through a method based on the genetic algorithm. The results show that, as expected, the Wong-Sandler mixing rules represented better the data, with both activity coefficient models showing high accuracy. However, in one case, NRTL predicted an erroneous azeotropic condition, while UNIQUAC was able to correlate the data without this error.     

甲醇、碳酸二甲酯、草酸二甲酯二元体系汽液平衡测定与关联

采用液上气相色谱法测定了一氧化碳低压气相催化合成碳酸二甲酯过程中3组二元物系甲醇-碳酸二甲酯、甲醇-草酸二甲酯、碳酸二甲酯-草酸二甲酯的等温汽液平衡数据。选用W ilson、NRTL、UNIQUAC活度系数方程进行了关联,利用关联出的模型参数计算相应的汽相组成,并与实验值比较,二者符合较好。     

醋酸脱水过程中对二甲苯+(醋酸,醋酸甲酯,醋酸正丙酯)和醋酸甲酯+醋酸正丙酯的二元汽液相平衡(英文)

The vapor-liquid equilibrium data of four binary systems (acetic acid +p-xylene, methyl acetate +n-propyl acetate, n-propyl acetate +p-xylene and methyl acetate +p-xylene) are measured at 101.33 kPa with Ellis equilibrium still, and then both the NRTL and UNIQUAC models are used in combination with the HOC model for correlating and estimating the vapor-liquid equilibrium of these four binary systems. The estimated binary VLE results using correlated parameters agree well with the measured data except the methyl acetate +p-xylene system which easily causes bumping and liquid rushing out of the sampling tap due to their dramatically different boiling points. The correlation results by NRTL and UNIQUAC models have little difference on the average absolute deviations of temperature and composition of vapor phase, and the results by NRTL model are slightly better than those by UNIQUAC model except for the methyl acetate +n-propyl acetate system, for which the latter gives more accurate correlations.     

加压下甲醇-水二元体系汽液平衡数据的测定及关联

用加压静态平衡釜测定了甲醇-水二元体系在353.15、373.15、388.15和403.15K下的汽液平衡数据。除373.15K外,其他3个温度点的数据未见文献报道,实验数据用含第二维里系数的截尾维里方程和5个活度系数方程关联。结果表明,所选计算模型均能很好地拟合实验数据,尤以维里方程加上Margules方程拟合精度最高。     

一种新的WS型混合法则

立方形状态方程被广泛应用于相平衡计算中．绝大多数状态方程是结合简单的van der Waals混合法则来进行VLE数据关联的．然而对于应用这些方程关联高度非理想混合物的复杂的相行为,仅用van der waals单维流体混合法则是不够的．甚至在van der Waals混合法则引入另外一个参数都不能够精确地关联含有极性物质的混合物．     

Vapor-liquid equilibria in the system of glycidol synthesis products

Vapor-Liquid equilibrium (VLE) data have been calculated for systems made up by glycidol synthesis products and have been compared with data available from the literature. The VLE data reported for the systems have been optimized using the NRTL and UNIQUAC models, and the model parameters and their accuracy have been estimated. The VLE in binary and multicomponent systems has been simulated.     

Extractive Distillation of p-Cresol/2,6-Xylenol Mixtures in the Presence of Alkanolamines

Abstract

The separation of p-cresol/2,6-xylenol mixtures has been investigated by extractive distillation in the presence of alkanolamines. The interaction parameters of liquid phase models, such as Wilson, NRTL, and UNIQUAC, have been estimated from binary vapor-liquid equilibrium data. The predicted relative volatility values for the p-cresol/2,6-xylenol mixtures in the presence of the alkanolamines were compared with experimental data.     

甲醇-甲醛-聚甲氧基二甲醚三元体系汽液平衡

聚甲氧基二甲醚(PODE_n)是一种含氧量较高的化合物,近年来更是发展为一种优质的柴油添加剂。在101.3 kPa恒定压力下,使用改进的汽液平衡双循环Rose釜测定了甲醇-甲醛-PODE₂三元体系汽液平衡数据。运用最大似然原理,在Aspen Plus软件中,分别采用NRTL、Wilson以及UNIQUAC三种活度系数模型对测定的三元汽液平衡数据进行回归,分别得到三个模型所对应的二元交互参数以及模拟计算值。通过对比模拟值与实验值,得到温度和气相组成的平均绝对偏差,分别小于1.10 K、0.0250和0.0240。三个模型的关联结果均适用于此体系,得到的二元交互参数能够应用于甲醇-甲醛-PODE₂三元体系的精馏设计,为相关物系的工业分离优化奠定了数据基础。