VAPOR-LIQUID EQUILIBRIA FOR PROPYLENE -METHANOL-WATER SYSTEM

In this article VLE data for a ternary system (propylene-methanol-water) under 30～60 C,0. 3～0. 9 MPa with a mass ratio of methanol to water of 9:1, 8: 2, 7: 3 were determined with a static equilibrium still, and were correlated by using Peng-Robinson model. The average relative error ofpropylene concentration in liquid phase is 1. 46 %. The results indicate that the models are very suitablefor the ternary system and the data are reliable.

VAPOR-LIQUID EQUILIBRIA FOR MIXTURES OF TOLUENE AND POLYSTYRENE WITH DIFFERENT MOLECULAR WEIGHTS

An experimental system for measuring the VLE of polymer solutions based on the staticvapor-pressure method has been established,VLE data for mixtures of toluene and polystyrene withdifferent molecular weight covering a wide range from 2.98×10~3 to 3.84×10~6 were obtained at 35℃.The reduced pressure p/p°versus weight fraction W plot is found to be independent on the molecularweight of the polymer within the experimental error.Calculated activity coefficients are also independenton the molecular weight.However,for the Flory-Huggins interaction parameter x,not only a strongconcentration dependence is observed,but also the molecular weight of the polymer exerts definiteinfluence.Generally,the parameter x slightly increases as the molecular weight of the polymer decreasesespecially when the molecular weight is low.The dependence of the parameter x on the molecularweight can be neglected when the molecular weight of polymer is greater than 1.00×10~4.

Vapor-Liquid Equilibria for Water+Hydrochloric Acid+Magnesium Chloride and Water+Hydrochloric Acid+Calcium Chloride Systems at Atmospheric Pressure

Vapor-liquid equilibria for water+hydrochloric acid+magnesium chloride and water+hydrochloric acid+calcium chloride systems at atmospheric pressure were measured using a Othmer-type equilibrium still. The experimental data are correlated using a modified Meissner’s method. Satisfactory agreements are obtained between the experimental and the calculated results.

The Performance of EOS Models in the Prediction of Vapor-Liquid Equilibria in Asymmetric Natural Gas Mixtures

The aim of this work is to apply cubic equations of state(EOS)to vapor-liquid equilibriacalculations of gas-heavy hydrocarbon systems,which are asymmetric in molecular size and areusually found in natural gases.Investigation has been done to test the validity of the original PSRKand the cubic simplified perturbed hard-chain(CSPhC)models for global phase diagrams.Thecalculation results show that both equations overpredict vapor pressure in the near critical region.In the prediction of the solubilities of high molecular weight(MW)hydrocarbons in the naturalgas,the PSRK model gives good agreement for the dew point pressure-vapor composition diagrams.Adjustment of the pure component parameters of the CSPHC EOS for heavy components to fit thevapor-liquid equilibrium(VLE)data has been proved to give significant promoting in predictionaccuracy.However,further improvement of a van der Waals EOS,such as SRK,PT and DG modelsfor the asymmetric systems by adjusting the three pure component properties,T_c, p_c and ?

A G^E/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.

VAPOR-LIQUID EQUILIBRIA BY EXTENDED SOAVE EQUATION OF STATE

The Soave[1]equation of state is extensively accepted because of its accuracy andsimplicity.In 1988,Tan et al.[2]suggested a modification by introducing atemperature-dependent factor to parameter"b"on the basis of statistical meaning,anda good accuracy was obtained for supercritical fluids as well as fluids approaching criti-cal conditions but not for mixtures.In the previous work,an extended Soave equa-tion of state[3]has been proposed to improve the prediction of liquid density.In thispaper,the extended equation is used to calculate vapor-liquid equilibria of mixtures atsubcritical conditions.

Measurement and Correlation of Vapor-Liquid Equilibria for Hexamethyl Disiloxane+Vinyl Acetate System at 101.3 kPa

Vapor-liquid equilibrium data of hexamethyl disiloxane+vinyl acetate system at 101.3kPa were measured by using double circulating vapor-liquid equilibrium still.The thermodynamic consistency of the VLE data was examined by Herrington method.Experimental data was correlated by non-random two-liquid(NRTL),Wilson and universal quasichemical(UNIQUAC)parameter models.All the models satisfactorily correlated with the VLE data.The result showed that the NRTL model was the most suitable one to represent experimental data satisfactorily.The system had a minimum temperature azeotrope at 345.71 K and the mole azeotropic composition was 0.0541.

Extension of LCVM-type mixing rule to three-parameter equations of state for vapor-liquid equilibria of mixtures

In this paper, the LCVM mixing rule is extended to the multi-parameter equations of state by combining infi- nite-pressure and zero-pressure mixing rule models. The new LCVM-type mixing rule, coupled with Patel-Teja equation of state (EOS) is applied for vapor-liquid equilibria of different polar and non-polar systems in which the NRTL activity coefficient model is used to calculate the excess Gibbs free energy. The tested results agree well with existing experimental data within a wide range of temperatures and pressures. In comparison with the Van der Waals mixing rule, the new mixing rule gives much better corre- lations for the vapor-liquid equilibria of non-polar and polar systems.

Modeling analysis of cobalt-based Fischer-Tropsch catalyst particles

The influences of particle size,shape,and catalyst distribution on the reactivity and hydrocarbon product selectivity of a cobalt-based catalyst for Fischer-Tropsch synthesis were investigated in the present work.A self-consistent kinetic model for Fischer-Tropsch reaction proposed here was found to correlate experimental data well and hence was used to describe the consumption rates of reactants and formation rates of hydrocarbon products.The perturbed-chain statistical associating fluid theory equation of state was used to describe vapor-liquid equilibrium behavior associated with Fischer-Tropsch reaction.Local interaction between intraparticle diffusion and Fischer-Tropsch reaction was investigated in detail.Results showed that in order to avoid the adverse influence of intraparticle diffusional limitations on catalyst reactivity and product selectivity,the use of small particles is necessary.Large eggshell spherical particles are shown to keep the original catalyst reactivity and enhance the selectivity of heavy hydrocarbon products.The suitable layer thickness for a spherical particle with a diameter of 2 mm is nearly 0.15 mm.With the same outer diameter of 2 mm,the catalyst reactivity and heavy product selectivity of hollow cylindrical particles with a layer thickness of 0.25 mm are found to be larger than eggshell spherical particles.From the viewpoint of catalytic performance,hollow cylindrical particles are a better choice for industrial applications.

N-甲酰吗啉-烷烃-芳烃间汽液平衡的研究

近年,采用N-甲酰吗啉溶剂回收芳烃在焦化行业中受到极大重视,但可资利用的基础数据却极为贫乏。今用改进的Junghans流动式鼓泡平衡釜测定了常压、三个温度(65.2, 72.5, 79.5℃)下苯-NFM二元体系和苯-环己烷-NFM、苯-正庚烷-NFM及苯-甲基环己烷-NFM三个三元体系共12组汽液平衡数据; 对所有三元体系, 分别以实测数据及苯-NFM的固定能量参数对,用NRTL和UNIQUAC模型进行了关联,结果均较为满意。研究结果填补了该项数据空白,完全能满足芳烃回收工程设计的需要。

新的N-甲酰吗啉UNIFAC基团相互作用参数

There are limited Vapor-Liquid Equilibrium（VLE） data in cluding N-formylmorpholine（NFM） for the design of the extractive distil lation process using NFM as solvent.The new interaction parameters of UNIFAC mo del were fitted with experimental data between CH2,ACH and NFM which was rega rded as a main group.Comparison of the prediction results of VLE data and infin ite dilution activity coefficients with other published methods of group divisio n for NFM, indicated more satisfying results with the interaction parameters of this paper. The four methods of group division for NFM were discussed based on the group division for ring molecule and group charge distribution. The group c harge distribution at the minimum energy state was calculated by the AM1 method in Chem3D Pro. The good theoretical basis was presented for the group division of NFM.

2个含异戊烯醇二元体系的减压汽液平衡

采用改进的Rose平衡釜测定了2-甲基-3-丁烯-2-醇+异戊烯醇、3-甲基-3-丁烯-1-醇+异戊烯醇体系在压力51.2和81.9 kPa下的汽液平衡数据,并通过热力学一致性检验。用Wilson和NRTL模型分别对实验数据进行了关联,获得了相应的二元交互作用参数。模型预测结果与实验数据吻合较好,2-甲基-3-丁烯-2-醇+异戊烯醇体系泡点温度和汽相组成的最大绝对偏差分别为0.4℃和0.0021,3-甲基-3-丁烯-1-醇+异戊烯醇体系泡点温度和汽相组成的最大绝对偏差分别为0.2℃和0.0031。热力学模型拟合结果满足工程设计的需要。

碳酸二甲酯-苯甲醇体系汽液平衡的研究

试验测定了碳酸二甲酯-苯甲醇体系在常压下的汽液平衡数据,采用Herrington法对数据进行了热力学一致性检验,结果表明所测数据符合热力学一致性。同时依据测定的汽液平衡数据计算出碳酸二甲酯及苯甲醇的无限稀释活度系数,求出Wilson活度系数模型参数,并计算了该体系于413.15 K的汽液平衡数据。

苯甲醇-甲醇与苯甲醇-乙醇二元体系汽液平衡

实验测定了苯甲醇-甲醇、苯甲醇-乙醇体系在常压下的汽液平衡数据,采用Herrington法对数据进行了热力学一致性检验,结果表明所测数据符合热力学一致性。同时依据测定的汽液平衡数据计算出苯甲醇及甲醇、乙醇的无限稀释活度系数,求出W ilson活度系数模型参数,并计算了苯甲醇-甲醇、苯甲醇-乙醇体系于303.15 K的汽液平衡数据。

苯-烷烃-NMP体系汽液平衡

用改进的Ｒｏｓｅ釜测定了１０１３ｋＰａ下苯烷烃ＮＭＰ体系的汽液平衡数据，对所测二元体系ＶＬＥ数据进行了热力学一致性积分和微分检验，用ＮＲＴＬ和ＵＮＩＱＵＡＣ方程进行关联，并用ＮＲＴＬ和ＵＮＩＱＵＡＣ方程的配偶参数推算出三元体系ＶＬＥ数据，与实测值比较，吻合良好。

New solvent blends for post-combustion CO2 capture

In the current work five different solvent blends are experimentally studied and the reboiler duties are calculated using the so-called short-cut method.Tertiary amines,2-(diethylamino)ethanol(DEEA),3-(Diethylamino)-1,2-propanediol(DEA-12PD),2-[2-(Diethylamino)ethoxy]ethanol(DEA-EO),1-(2-Hydroxyethyl)piperidine(12HE-PP)are blended with 3-(Methylamino)propylamine(MAPA)and ethanolamine(MEA).The first results from simple solvent screening are given and the cyclic capacities are calculated based data at 40℃ and 80℃.Then,five solvent systems are chosen for vapor–liquid equilibrium characterization.The vapor–liquid equilibrium data are then used to estimate cyclic capacities at more realistic temperatures,between 40℃ and 120℃ and by using a short-cut method proposed in the literature the reboiler duties of the characterized solvents are estimated.Finally,the potential of the studied systems is discussed.Several of the characterized blends showed reboiler duties around 2.5 MJ kgCO2^-1.

Theoretical research on vacuum separation of Au-Ag alloy

To provide an accurate prediction of the product component dependence of temperature and pressure in vacuum distillation and give convenient and efficient guidance for the designing of the process parameters of industrial production, according to the molecular interaction volume model(MIVM), the separation coefficient(β) and vapor-liquid equilibrium composition of Au-Ag alloy at different temperatures are calculated. Combined with the vapor-liquid equilibrium(VLE) theory, the VLE phase diagrams, including the temperature-composition(T-x) and pressure-composition(p-x) diagrams of Au-Ag alloy in vacuum distillation are plotted. The triple points and condensation temperatures of gold and silver vapors are calculated as well. The results show that the β decreases and the contents of gold in vapor phase increase with the distillation temperature increasing. Low pressures have positive effect on the separation of Ag and Au. The difference between the condensation temperatures of gold and silver is about 450 K in the pressure range of 1-10 Pa.

Estimation and Test of Interaction Parameters in the UNIFAC Model of Group-OCOO-with Group-CH_3,ACH, CH_3OH and CH_3COO-

Isobaric vapor-liquid equilibria (VLE) are experimentally measured for the binary systems of dimethyl carbonate (DMC)+ ethylene carbonate and methanol + ethylene carbonate at 101.325kPa. The thermodynamic consistency of these experimental data is tested with an available statistic method. Interaction parameters of the carbonate group -OCOO- with the group -CH3, ACH, CH3OH and CH3COO- in UNIFAC model are determined using the experimental and literature VLE data. The results show that the calculated VLE data using the new UNIFAC parameters agree excellently with the experimental data in this work and in literature. These results are useful in the research on DMC and diphenyl carbonate synthesis by transesterification in design of reactor and distillation tower.

Needs of thermodynamic properties measurements and modeling in the frame of new regulations on refrigerants

In 1987, the Montreal Protocol prohibited the worldwide use and production of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) and hydro fluorocarbons (HFCs) were proposed as alternative refrigerants. Unfortunately, HFCs have non negligible global warning potential and therefore new refrigerants must be proposed or old refrigerants must be used associated with HFC. Accurate experimental thermodynamic data and predictive techniques are required for better under-standing of the performance of the newly proposed refrigerants. In this communication, experimental techniques based on either analytic or synthetic methods are first described. Data are reported. Then two newly developed predictive models based on thermodynamic approach with the isofugacity criterion and artificial neural network method are presented. The results can provide better evaluation of refrigerants, especially with the aim of studying global warning effects.

A four parameter cubic equation of state with temperature dependent covolume parameter

A four-parameter, Ghoderao–Dalvi–Narayan 2 cubic equation of state(GDN2 CEOS), is presented which incorporates the following: 1. The experimental value of the critical compressibility factor has been used as a fixed input parameter for calculations;2. All the parameters(a, b, c, d) of CEOS are temperature dependent functions in the subcritical region and are temperature independent functions in the supercritical region and;3. A new α function is introduced with two compound specific parameters which are estimated by matching saturated vapor pressure at two fixed temperature points Tr= 0.5, 0.7. Our formalism enables us to cast three of the four parameters of the CEOS as a function of the remaining parameter. The proposed CEOS is used to predict properties of 334 pure compounds, including saturated vapor pressure and liquid density, compressed liquid density, heat capacities at the constant pressure and volume, enthalpy of vaporization, sound velocity. To calculate thermodynamic properties of a pure compound, the present CEOS require the critical temperature, the critical pressure, the Pitzer’s acentric factor, the critical compressibility factor, and two parameters of the alpha function. The saturated liquid density predictions for pure fluids are very accurate when compared with GDN1(Ghoderao–Dalvi–Narayan 1),MPR(Modified Peng–Robinson), and PT(Patel–Teja) equations of state. Unlike MPR EOS, the proposed temperature dependent covolume parameter b in the present work satisfies all the constraints mentioned in the literature to avoid thermodynamic inconsistencies at the extreme temperature and pressure. Using van der Waals one-fluid mixing rule, the present CEOS is further used to predict bubble pressure and the vapor mole fraction of binary mixtures.