Simulation modeling of the phase behavior of palm oil-supercritical carbon dioxide

The phase behavior of crude palm oil (CPO) with supercritical CO₂ was successfully modeled in an Aspen Plus^® 10.2.1 commercial simulator (Aspen Technology Inc., Cambridge, MA) using the Redlich-Kwong-Aspen (RKA) equation of state thermodynamic model. The modeling procedure involved estimating pure component vapor pressures and critical properties and computing a regression of phase equilibrium behavior. The interaction parameters for the RKA model were obtained from the regression of experimental phase equilibrium data for a binary system of palm oil components-supercritical CO₂ available in the literature. The distribution coefficients and solubilities of palm oil components obtained from this simulation showed good agreement with experimental data obtained from the literature. The model provides an efficient and cost-effective alternative for the preliminary design and optimization of a supercritical fluid extraction process involving a complex CPO-supercritical CO₂ system.     

A multi-fluid nonrandom lattice fluid model: Mixtures

A multi-fluid nonrandom lattice fluid model with no temperature dependence of close packed volumes of a mer, segment numbers and energy parameters of pure systems and its consistent method for phase equilibrium calculation were presented in the previous paper. In this work, the model was extended to mixtures by using consistent method for phase equilibrium calculation with fugacity coefficients derived from the present equation of state and it was applied to vapor-liquid equilibrium. We consistently tested the present model on 17 phase equilibrium data sets of vapor-liquid equilibria and compared it with the MF-NLF model and the SAFT model. The present model (3 pure parameters for pure component and one binary interaction parameter) showed better results for most systems than the MF-NLF model (6 adjustable pure parameters and one binary interaction parameter) and the SAFT model (3 pure parameters and one binary interaction parameter).     

EOS状态下基于多相流有规栅格理论的水-碳氢化合物两相体系的临界轨迹关系

Quantitative representation of complicated behavior of fluid mixtures in the critical region by any of equation-of-state theories remains as a difficults thermodynamic topics to date.In the present work,a computational efforts were made for representing various types of critical loci of binary water with hydrocarbon systems showing Type Ⅱ and Type Ⅲ phase behavior by an elementary equation of state[called multi-fluid nonrandom lattice fluid EOS(MF-NLF EOS)]based on the lattice statistical mechanical theory.The model EOS requires two molecular parameters which representing molecular size and interaction energy for a pure component and single adjustable interaction energy parameter for binary mixtures.Critical temperature and pressure data were used to obtain molecular size parameter and vapor pressure data were used to obtain interaction energy parameter.The MF-NLF EOS model adapted in the present study correlated quantitatively well the critical loci of various binary water with hydrocarbon systems.     

Calculation of complex phase equilibria in the critical region of fluid mixture based on multi-fluid lattice equation of state

Quantitative correlation of critical loci and multiphase behaviors has received considerable attention because the increased industrial importance of processes operating within the high-pressure region such as supercritical fluid extraction. However, in the critical region, classical thermodynamic models such as equations of state (EOS) frequently fail to correlate phase equilibrium properties. Recently, the present authors proposed a new lattice-hole EOS based on the multi-fluid approximation of the nonrandom lattice theory. The model requires only two molecular parameters reflecting size and interaction energy for a pure fluid and one additional interaction parameters for a binary mixture. In this work, the reliable applicability of the EOS was demonstrated to various phase equilibria of complex mixtures in the critical region. Demonstration of the EOS was made to calculate multiphase behaviors such as solid-liquidvapor (SLV) equilibria and critical loci of binary complex mixtures at high pressure. For P-T, P-x, and T-ρ phase diagrams tested, the model agrees well with experimental data. This paper was presented at the 8th APCChE (Asia Pacific Conferation of Chemical Engineering) Congress held at Seoul between August 16 and 19, 1999.     

Phase equilibria of mixtures containing CO2 and organic acids using the UMR-PRU model

The UMR-PRU model, which has been successfully tested in the past to the predictions of different type of phase equilibrium and thermodynamic properties in binary and multicomponent systems, is applied in this work to phase equilibria in mixtures containing CO₂ and organic acids. New interaction parameters are determined by fitting only binary vapor–liquid equilibrium data and then they are used to predict the vapor–liquid, solid–gas and solid–liquid–gas equilibria in CO₂/organic acid systems. Furthermore, the UMR-PRU model with the newly derived interaction parameters is applied to the prediction of the phase equilibrium in ternary mixtures consisting of CO₂, organic acids and water. Satisfactory results are obtained in all cases.     

用密度泛函理论研究非极性混合流体表面性质

应用密度泛函理论研究了二元非极性混合流体的表面性质.分子作为球形链处理,不同分子内的两链节相互作用以硬核Yukawa势能表示.为了避免计算中势能作用数值积分截断导致的误差,采用了合理的长程校正方法.根据微扰理论建立了流体的状态方程以计算汽液相平衡.从纯流体汽液相平衡数据回归得分子的链节作用参数ε/k、d和m_s,这些参数预测纯流体表面张力时可获得较好结果.继而引入混合参数k_ij表示不同分子链节作用情况,计算了6种非极性混合流体的汽液相平衡、表面张力、表面密度剖面.结果表明,本方法应用于二元非极性流体混合物时汽液表面张力计算值与实验值符合良好,同时显示某些二元混合流体表面区可能出现组分的相对富集现象.     

基于Eyring绝对速率理论的流体混合物黏度推算

为了建立起一个统一的、可同时应用于纯质与混合物高压黏度计算的绝对速率理论模型,基于此前已有的纯质黏度模型,提出了相应的混合法则,将其扩展至对混合流体的计算当中。为验证模型精度,首先选取了27种纯质流体,通过拟合其黏度数据得到模型参数。随后,对27种二元混合物以及3种三元混合物的黏度进行了计算。其中,对于二元混合物,仍需要引入额外的二元交互参数,可通过拟合混合体系黏度数据得到。结果表明,该黏度模型对所选纯质、二元混合物和三元混合物的黏度均有着较高的计算精度,其相对偏差的平均绝对值分别为1.54%、2.35%和3.86%,最大偏差为8.62%、12.9%和19.7%。最后,将本文模型与自由体积模型进行了比较,其对高黏度和互缔合流体的计算精度均高于后者。     

AN EQUATION OF STATE FOR AQUEOUS ELECTROLYTE SYSTEMS——Prediction of The Solubility of Natural Gas in Formation Water

A new equation of state(PHSMSA EOS)based on perturbation theory is developed for calculating high-pressure phase equilibria of aqueous electrolyte systems containing supercritical gases,light hydrocarbons andpolar components.The binary interaction parameters are determined:for ion-ion pairs by regression of ionicactivity coefficient data;for molecule-molecule pairs by fitting the VLE data of binary nonelectrolyte mixtures;and for ion-molecule pairs by fitting the gas solubility data of ternary gas-water-salt systems.The new EOShas been tested on the prediction of solubilities of methane,nitrogen and natural gas mixtures in brine.Sat-isfactory agreement with the experimental data measured by authors and other investigators is observed.     

N,N-二甲基甲酰胺+醇二元混合物的黏度测定与关联

在288.15~313.15 K和常压下,利用乌氏黏度计测定了N,N-二甲基甲酰胺（DMF）分别与乙醇、丙醇、乙二醇和1,2-丙二醇组成的二元系全浓度范围内的黏度,计算了过量黏度△η和过量流动活化自由能△G^*E。用Redlich-Kister方程对过量黏度进行了关联;用黏度模型如Frenkel方程,Grunberg-Nissan方程,Katti-Chaudhari方程和McAllister方程对实验黏度数据进行了关联和预测,并利用Eyring理论方法计算了流动活化自由能、活化焓和活化熵等热力学函数。结果表明,4个二元系的过量黏度和过量流动活化自由能均为负值,且都随温度降低而偏差增大。过量黏度最低值均发生在DMF摩尔分数约为0.3处。McAllister模型对黏度数据的关联结果最好,预测值与实验值的平均相对偏差最小。比较并分析了DMF与一元醇和二元醇之间分子相互作用的差异。。     

Densities and viscosities for ionic liquids [BMIM][BF4] and [BMIM][Cl] and their binary mixtures at various temperatures and atmospheric pressure

The density and viscosity of 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF₄] and 1-butyl-3-methylimidazolium chloride [BMIM][Cl] and their binary mixtures within the temperatures from 303.15 K to 323.15 K and at ambient pressure were determined in this work. The temperature dependences of density and viscosity were satisfactorily described with the linear model and the Vogel-Tammann-Fulcher type equation, respectively. The molar volume and viscosity of binary IL mixtures were predicted through ideal mixing rules showing that almost null deviations for IL mixtures were observed and their mixing was remarkably close to linear ideal behavior in the molar volumes, while comparatively large errors in viscosity occurred. Additionally, the molar volume of the investigated pure ILs and their mixtures could well be predicted by a predictive model presented by Valderrama et al. (Fluid Phase Equilib., 275 (2009) 145).     

The isolation of pyrolysis oil from castor seeds via a Low Temperature Conversion (LTC) process and its use in a pyrolysis oil-diesel blend

A Low Temperature Conversion (LTC) process carried out on a sample of castor seeds, Ricinus communis, generated fractions of pyrolysis oil, pyrolitic char, gas and aqueous extracts in the following relative amounts, respectively: 50%, 28%, 10% and 12% [w/w]. The pyrolysis oil was added at loadings of 2%, 5%, 10%, 20% and 30% [w/w] to commercial diesel. The density, viscosity, sulfur content, glow point, volatility and cetane index of these mixtures were determined. The results indicate that the addition of pyrolysis oil to commercial diesel results in fuel mixtures within the norms of ANP diesel directive no 15, made on 19. 7. 2006, with the exception of the 20% mixture (which has an unfavorable viscosity) and the 30% mixture (which has an unfavorable viscosity and volatility).     

Unified equation of state based on the lattice fluid theory for phase equilibria of complex mixtures part II. Application to complex mixtures

In part I of the present article [Yoo et al., 1995], new rigorous and simplified lattice-fluid equations of state (EOS) were derived and their characteristic features of the molecular thermodynamic foundation were discussed by applying to pure fluids. In this part II, both EOSs were extended to various phase equilibrium properties of mixtures. Comparison of the models with experimental mixture data ranges from density, to equilibria of vaporliquid, vapor-solid and liquid-liquid phases for nonpolar/nonpolar, nonpolar/polar, polar/polar mixtures. Both models were also applied to supercritical fluid phase equilibria and activities of solvents in polymer solutions. With two temperature dependent parameters for pure compounds and one temperature-independent binary interaction energy parameter for a binary mixtures, results obtained to date illustrated that both EOSs are quantitatively applicable to versatile phase equilibria of mixtures over a wide range of temperatures, pressures and compositions.     

Orientation effect on sign and magnitude of excess thermodynamic functions of non electrolyte solutions at different temperatures (303.15 K, 308.15 K,and 313.15K)

Experimental values of the density and viscosity have been measured for binary mixtures of N-ethylaniline with isomeric butanols (1-butanol, 2-butanol, 2-methyl-1-propanol and 2-methyl-2-propanol) at 303.15, 308.15 and 313.15 K over the entire mole fraction range. These data, the excess molar volumes, and deviation viscosity for the binary systems at the above-mentioned temperatures were calculated and fitted to Redlich-Kister equation to determine the fitting parameters and the root-mean-square deviations. The excess molar volumes, deviation viscosity and excess Gibbs energy of activation of viscous flow have been analyzed in terms of acid-base interactions, hydrogen bond, and dipole-dipole interaction between unlike molecules. The results obtained for dynamic viscosity of binary mixtures were used to test the semi-empirical relations of Grunberg-Nissan, Katti-Chaudhri, and Hind et al. equations.     

垂直上升管内气体扰动油水两相乳化液流动特性

气体 -油水乳化液的管内流动是原油开采、油气输运以及许多化工领域中经常遇到的工程现象 ,正确认识油水乳化液在气体扰动下的动力特性对圆管内油、气、水多相流的理论建模具有重要的工程应用和学术价值 .本文通过垂直上升管内油气水三相弹状流的实验研究 ,提出了垂直上升弹状流中油水乳化液黏度计算模型 .基于此模型 ,油水乳化液在气体掺入下的流动特性可表现为气体扰动变稠的非牛顿流体特性和气体扰动变稀的非牛顿流体特性 .     

状态方程模拟醇胺系统的密度和汽液相平衡

通过考虑醇胺分子间的缔合作用,结合先前开发的非缔合变阱宽链流体状态方程(SWCF-VREOS)建立了一个缔合方阱链流体状态方程,并利用方程模拟了醇胺系统的密度和汽液相平衡。通过关联不同温度下醇胺的饱和蒸气压和液体体积得到了18种醇胺流体的分子参数,新方程计算的饱和蒸气压和液体密度总的平均误差分别为0.94%和0.88%。结合简单的混合规则,将此方程扩展到混合系统。研究发现,建立的方程可预测二元和三元醇胺混合物的密度。当引入一个与温度无关的可调参数时,方程能满意关联二元系统的汽液相平衡数据,并可进一步预测多元混合系统的汽液相平衡,预示着新方程可模拟醇胺系统的相行为。     

MOLECULAR PRINCIPLE OF CORRESPONDING STATES FOR VISCOSITY AND THERMAL CONDUCTIVITY OF FLUID MIXTURES

Conformal solution theory is developed for the viscosity and thermal conductivity of fluid mixtures. The procedure involves expanding the transport coefficient for the mixture about the value for an ideal solution, using groupings of the potential parameters and molecular mass as expansion coefficients. The parameters for the ideal solution are chosen so as to annul the first-order term in this expansion, thus encouraging rapid convergence. This yields mixing rules (similar to those of the van der Waals 1 theory for thermodynamic properties) for the potential parameters and molecular mass of the reference fluid. Reference fluid properties are obtained from pure fluid corresponding states correlations

By making calculations for dilute gas mixtures and comparing with Chapman-Enskog theory, it is found that the first-order theory works well for mixtures of quite widely different energy parameters (ε) and molecular masses; it is more sensitive to the size difference of the molecular components, however. For cryogenic liquid mixtures composed of simple liquids good results are obtained using two-parameter corresponding states for the reference fluid. For polyatomic fluids it is necessary to use a three-parameter corresponding states approach for the pure fluids. A method of introducing a third parameter, while retaining the simplicity of having only two independent variables, is used for such fluids. Good results are obtained for a variety of binary mixtures. The method is of particular value for multicomponent fluids. Thus, without fitting any parameters from ternary data the theory predicts viscosities for the system carbon tetrachloride/n-hexane/benzene over the full composition range with a standard deviation of only 1.69%.     

FLOW CHARACTERISTICS OF GAS-OIL-WATER EMULSION IN PIPES

气体 -油水乳化液的管内流动是原油开采、油气输运以及许多化工领域中经常遇到的工程现象 ,正确认识油水乳化液在气体扰动下的动力特性对圆管内油、气、水多相流的理论建模具有重要的工程应用和学术价值 .本文通过垂直上升管内油气水三相弹状流的实验研究 ,提出了垂直上升弹状流中油水乳化液黏度计算模型 .基于此模型 ,油水乳化液在气体掺入下的流动特性可表现为气体扰动变稠的非牛顿流体特性和气体扰动变稀的非牛顿流体特性 .     

CF_4和惰性气体混合物的输运性质的计算

The present work is concerned with determining the viscosity, diffusion, thermal diffusion factor and thermal conductivity of five equimolar binary gas mixtures including: CF_4-He, CF_4-Ne, CF_4-Ar, CF_4-Kr, CF_4-Xe from the principle of corresponding states of viscosity by the inversion technique. The Lennard-Jones (12-6) model potential is used as the initial model potential. The calculated interaction potential energies obtained from the inversion procedure is employed to reproduce the viscosities, diffusions, thermal diffusion factors, and thermal conductivities. The accuracies of the calculated viscosity and diffusion coefficients were 1% and 4%, respectively.