SRK方程结合超额Gibbs自由能规则预测汽液平衡

SRK方程结合范德华混合规则应用于极性体系会产生较大误差,而结合超额Gibbs自由能(GE)型混合规则能得较好的结果。Wong-Sandler(WS型)混合规则是基于无穷大压力的GE型混合规则,文中对提出一种基于常压的改进型WS(MWS型)混合规则,利用SRK方程分别结合WS型和MWS型混合规则对多个二元极性体系汽液平衡进行预测。比较结果表明,采用SRK方程结合MWS型混合规则预测汽液平衡结果一般优于WS型混合规则。     

SRK方程α的改进及其在汽-液相平衡预测中的应用

Based on results of saturated vapor pressures of pure substances calculated by SRK equation of state,the factor α in attractive pressure term was modified. Vapor-liquid equilibria of mixtures were calculated by original and modified SRK equation of state combined with MHV1 mixing rule and UNIFAC model, respectively. For 1447 saturated pressure points of 37 substance including alkanes; organics containing chlorine, fluorine, and oxygen; inorganic gases and water, the original SRK equation of state predicted pressure with an average deviation of 2.521% and modified one 1.673%. Binary vapor-liquid equilibria of alcohols containing mixtures and water containing mixtures also indicated that the SRK equation of state with the modified α had a better precision than that with the original one.     

Gibbs-Duhem方程与前传网的集成方法及其在汽液相平衡中的应用

提出了以Gibbs-Duhem方程为基架,引入前传网,由此将机理方程与神经网络这两种不同类的方法相集成,用以求解化工热力学的汽液相平衡问题,以克服经典的机理方法或单一神经元方法的欠缺与不足。将这种集成方法应用于恒温、恒压二元体系,由液相组成确定汽相组成,效果良好。应用实例表明该法计算简便,预测精度高,且稳定性好,显示出胜于两种单一方法的优越性。     

SRK状态方程用于聚合物体系的汽液和气液平衡

A simple extension of cubic equations of state （EOS） to polymer systems has been proposed. The Soave-Redlich-Kwong （SRK） EOS was taken as a prototype to be used to describe the PVT behavior of polymer melts in a wide temperature and pressure range. Combined with a modified Huron-Vidal gE-mixing rule it was applied for modeling vapor-liquid equilibria of polymer-solvent solutions and the solubility of supercritical gases in polymer melts. Satisfactory results are obtained.     

含辛烯醛体系的液液、汽液相平衡研究

测定了水-辛烯醛、水-正丁醇二元系在常压下的液液平衡数据及26.66kPa下的正丁醇-辛烯醛二元系和水-正丁醇-辛烯醛三元系的汽液平衡数据.由测定的3对二元数据求取了NRTL常数及有规参数,并与三元数据进行拟合,计算值与实验值符台良好,液液平衡与汽液平衡得到了统一的关联.     

异戊醇-乙二醇体系等压汽液相平衡研究

利用双循环汽液平衡釜测定 10 1.3kPa下异戊醇 乙二醇体系的汽液平衡数据x y t,并运用该实验结果 ,进一步获得组分的液相活度系数。实验数据经Herrington方法检验 ,表明符合热力学一致性。用Wil son模型对该实验数据进行处理 ,计算结果与实验值的平均绝对偏差为 0 .0 0 6 3,取得满意的效果。     

苯、间二甲苯-水二元体系汽液相平衡

采用改进的Partt釜测定了在0.1013MPa下,苯-水和间二甲苯-水二元部分互溶体系的汽液相平衡数据,经热力学一致性检验表明,测定数据可靠。     

碳酸二甲酯-乙醇体系等压汽液相平衡

采用双循环汽液平衡釜测定了碳酸二甲酯-乙醇在100 kPa下的汽液平衡数据。实验数据经Herington面积积分法校验符合热力学一致性。运用M atlab中的非线性最小二乘法程序,对二元汽液平衡的W ilson模型进行参数计算,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,其平均绝对偏差为0.002 8,表明二者符合良好,这为建立碳酸二甲酯和乙醇的精馏分离数学模型提供了基础数据。     

MHVOS混合规则在高压汽液相平衡中的应用

为改进HVOS混合规则应用于非对称体系汽液平衡的能力,将混合规则能量参数表达式中的结合项与活度系数模型UNIFAC结合项中的Flory-Huggins部分进行相互抵消,并相应地修改交叉体积参数项。利用改进后的混合规则MHVOS,结合Peng-Robinson状态方程及UNIFAC模型对14种二元体系的高压气液相平衡进行预测,并与HVOS和MHV1混合规则比较。结果表明,对于小分子且相对分子质量相近的极性或烷烃类二元体系MHVOS混合规则预测能力并未得到提高。而针对相对分子质量差距较大非对称性强的烷烃类二元体系,HVOS和MHV1混合规则的预测精度均明显下降,MHVOS混合规则的预测精度反而有所提高。     

PR方程与SRK方程在计算水露点中的比较与应用

水露点是天然气管道输送安全的一个重要指标。介绍了PR方程与SRK方程,利用两个方程的不同混合法则及相平衡计算,通过编写程序,计算出在相同条件下,不同方程之间计算出的水露点的差异,得出利用PR方程计算出的水露点较SRK方程计算的结果偏低。     

由修正的SRK方程推算HF饱和蒸汽压

对ＳＲＫ方程吸力项温度依变参数作了修正，使之能精确的推算了ＨＦ体系的饱和蒸汽压。     

A Modification of α in SRK Equation of State and Vapor-Liquid Equilibria Prediction

1 INTRODUCTION Equations of state (EOS), especially, cubic equa-tions of state are frequently used in modeling phase equi-librium for chemical process of designing. Among cubic equations of state, SRK[1] equation of state and PR[2] equation of state are the most commonly used. These two equations of state are similar in form. They are also similar in the correction factor of parameter a. When phase equilibria of mixtures were calculated, equations of state must be combining with mixing…     

A GE/Equation of State Mixing Rule for Vapor-Liquid Equilibria

A new excess Gibbs free energy/equation of state type mixing 0rule was derived byremoving the infinite pressure boundary condition imposed by Wong and Sandler.The mixing rulewas extensively tested in terms of a comprehensive data base,consisting of 52 simple nonpolar-nonpolar,carbon dioxide containing,hydrocarbon-hydrocarbon,CFC,polar-polar,nonpolar-polarbinary and multicomponent systems.Focused on the complete predictive capability,a comparisonbetween the Wong-Sandler and the mixing rule proposed was conducted.The results indicate that thenew mixing rule is in general superior to the Wong-Sandler's,and the binary interaction parameteras required by the latter is removed,which reduces computing effort and is reliable in predictions ofvapor-liquid equilibria from low pressures to high pressures.     

运用方程预测汽液平衡下的饱和蒸汽压

运用Antoine方程、Lee-Kesler对比态方程和PR状态方程预测异丁烷的饱和蒸汽压,结果表明三个方程都有较好的精度。其中Lee-Kesler对比态方程计算更为简洁,适用的温度范围广等特点。     

应用PSRK状态方程预测高压汽液平衡

为预测高压汽液平衡,将过量吉布斯自由能混合规则和UNIFAC活度系数模型与SRK状态方程相结合,建立基团贡献状态方程PSRK。利用该状态方程对5个体系在不同压力和温度下的汽液平衡数据进行了关联实验测定的汽相压力和汽相组成与计算结果相比所得的相对平均偏差分别为2．16％和1．01％。结果表明,PSRK状态方程可以成功地预测高压下汽液平衡,其精度高于MHV1和MHV2模型。     

A GE/Equation of State Mixing Rule for Vapor-Liquid Equilibria

A new excess Gibbs free energy/equation of state type mixing 0rule was derived by removing the infinite pressure boundary condition imposed by Wong and Sandler. The mixing rule was extensively tested in terms of a comprehensive data base, consisting of 52 simple nonpolar-nonpolar, carbon dioxide containing, hydrocarbon-hydrocarbon, CFC, polar-polar, nonpolar- polar binary and multicomponent systems. Focused on the complete predictive capability, a comparison between the Wong-Sandler and the mixing rule proposed was conducted. The results indicate that the new mixing rule is in general superior to the Wong -Sandler’s, and the binary interaction parameter as required by the latter is removed, which reduces computing effort and is reliable in predictions of vapor-liquid equilibria from low pressures to high pressures.     

改进SRK方程提高正构烷烃饱和蒸气压和液体体积预测精度

<正>引言 在化学工程和油藏工程的相平衡和其他热力学性质计算中,两参数立方型SRK方程应用最为广泛。然而,在某些情况下由SRK方程预测的饱和蒸气压出预测的液体体积偏差较大,无法满足工程计算的需要,必须改进方程,提高其预测精度。1 饱和蒸气压的改进 SRK方程可以写为 p=RT/（V-b）-(a(T)）/V(V+b) （1）     

A New Approach to Investigation of vdW Type of Equations of State

A new approach to the investigation ofvdW type of equations of state (EOS) is developed by embedding a vapor pressure equation and a saturated liquid volume equation into vdW type EOS, which resuits in a new function A^s(T). The A^s(T) possesses the properties of an attractive parameter A(T), and if an EOS is accurate in the whole PVT space, then its numerical wahie equal8 A(T). As a useful tool for investigating EOS, the A^s(T) has been used to make comparisons among RKS, PRSVII, PT and ALS EOS, and to indicate where the shortcomings of the EOS are coming from. Based or. the A^s(T), a possible way to develop at real predictive equation of state is also suggested.     

立方型+缔合状态方程模拟离子液体的pVT性质和汽液平衡(英文)

Combining Peng-Robinson (PR) equation of state (EoS) with an association model derived from shield-sticky method (SSM) by Liu et al., a new cubic-plus-association (CPA) EoS is proposed to describe the ther-modynamic properties of pure ionic liquids (ILs) and their mixtures. The new molecular parameters for 25 ILs are obtained by fitting the experimental density data over a wide temperature and pressure range, and the overall aver-age deviation is 0.22%. The model parameter b for homologous ILs shows a good linear relationship with their mo-lecular mass, so the number of model parameters is reduced effectively. Using one temperature-independent binary adjustable parameter kij, satisfactory correlations of vapor-liquid equilibria (VLE) for binary mixtures of ILs + non-associating solvents and + associating solvents are obtained with the overall average deviation of vapor pressure 2.91% and 7.01%, respectively. In addition, VLE results for ILs + non-associating mixtures from CPA, lattice-fluid (LF) and square-well chain fluids with variable range (SWCF-VR) EoSs are compared.