Isobaric vapor-liquid equilibrium for methyldichlorosilane-methyltrichlorosilane-dimethyldichlorosilane system

This paper describes measurement of vapor-liquid equilibrium (VLE) data of methyldichlorosilane-methyltrichlorosilane-dimethyldichlorosilane system and that of the three binary systems at 101.325 kPa with a new pump-ebulliometer. The equilibrium composition of the vapor phase was calculated from pTx by indirect method. The model parameters of the liquid activity coefficient of the Wilson, NRTL, Margules and van Laar equations was corrected by the least square method. The ternary system VLE data were predicted by the Wilson equation, with the calculated boiling points showing good agreement with the experimental data.     

Isobaric vapor-liquid equilibrium for toluene, 3-methylthiophene and N-formylmorpholine at 101.33 kPa

Isobaric vapor-liquid equilibrium(VLE)data were measured for binary mixtures of toluene+N-formylmorpholine,toluene+3-methylthiophene and 3-methylthiophene+N-formylmorpholine at 101.33 kPa.The VLE data ...     

减压下N，N-二甲基乙酰胺-水二元汽液平衡数据的测定与关联

采用改进的Ellis汽液平衡釜,在35kPa压力下,测定了N,N-二甲基乙酰胺一水二组分物系的汽液平衡数据．利用Herington面积检验法对实验数据进行了热力学一致性检验,结果表明,所测定的汽液平衡数据满足热力学一致性．分别用VanLaar和Wilson活度系数方程关联了实验数据,两者结果较接近．汽相组成和泡点温度的平均绝对误差分别为0．0041,1．622l℃（VanLaar）和0．0076,1．6057℃（wilson）．实验数据和关联结果为减压精馏分离N,N-二甲基乙酰胺和水的过程开发提供了基础数据．     

Measurement and Correlation of Isobaric Vapor-Liquid Equilibrium of Three Binary Systems Containing Chlorobenzene at 50.00 and 101.33 kPa

Isobaric vapor-liquid equilibrium(VLE) data for three binary systems, chlorobenzene + N,N-dimethylformamide, chlorobenzene + furfural, and chlorobenzene + benzaldehyde, were measured at 50.00 and 101.33 kPa using a modified Rose-Williams still. Gas chromatography was used to analyze the compositions of the samples and no azeotropic behavior was found. All of the measured VLE values were checked by the semi-empirical method proposed by Herington and the point-to-point Van Ness test method modified by Fredenslund. The experimental data were correlated by using the Wilson, the non-random two-liquid and universal quasi-chemical activity coefficient models. The corresponding parameters for the three models were obtained.     

Vapor-liquid equilibrium simulation of binary and ternary mixtures of CH4, C2H4 and iso-C4H10

The vapor-liquid equilibrium（VLE） properties for the binary and ternary mixtures of CH4,C2H4 and isoC4H10 are of great importance in the recovery of ethylene from mixture containing CH4 and C2H4 with iso-C4H10 as solvent.Hence,Gibbs ensemble Monte Carlo（GEMC） simulations were used to estimate vapor-liquid equilibrium for the binary and ternary mixtures of CH4,C2H4 and iso-C4H10 with the united atom potential NERD model.The selected simulation conditions are based on the experiment in the literature.The results of this work were shown to be in satisfactory agreement with available experimental data and predictions of Peng-Robinson equation of state.The structure of simulated liquid phase is also characterized by radial distribution function（RDF）,which contributes to further understanding of the VLE curve of these systems.RDF is not sensitive to the pressure and temperature range.With the increase of pressure or the decrease of temperature,the molecules tend to gather together.     

High Pressure Vapor-Liquid Equilibrium of Supercritical Carbon Dioxide ＋ n-Hexane System

Vapor-liquid equilibrium data are important forthe design, development, and operation of supercriti-cal fluid separation processes[1].The main method forobtaining phase equilibrium data is experimentation.Most published articles on high-pressure fluid-phaseequilibrium experimental methods focus on supercriti-cal (SC) carbon dioxide because of its low criticaltemperature and pressure, nontoxicity, and lowcost. A feature of SC fluids is that their densities anddensity-dependentproperties are s…     

DMF-CHCl_3体系汽液相平衡数据的测定与关联

为获得二甲基甲酰胺(DMF)与氯仿(CHCl3)精馏分离的基础热力学数据,实验采用改进型的Rose平衡釜测定了DMF-CHCl3体系在760mmHg下的汽液相平衡数据,并分别用NRTL和Margules模型对实验数据进行关联。结果表明:实验数据满足热力学一致性的检验,且NRTL和Margules模型的计算结果与实测结果偏差小,平均绝对误差分别为0.0026和0.0010,平均相对误差分别为1.81%和1.23%,可满足工业精馏工艺过程设计的需要。     

Calculation of the Phase Equilibrium of CO_2–Hydrocarbon Binary Mixtures by PR-BM EOS and PR EOS

The phase equilibrium data of CO_2 –hydrocarbon binary mixtures are important for the design and operation of CO_2 flooding, coal liquefaction, and supercritical extraction processes. Numerous pieces of binary phase equilibrium data have been obtained. Thus, models for the accurate calculation of binary and multicomponent mixtures must be developed on the basis of existing data. In this work, 3578 vapor–liquid phase equilibrium data points for 10 CO_2 –hydrocarbon binary mixtures, including CO_2 –butane, CO_2 –pentane, CO_2 –isopentane, CO_2 –hexane, CO_2 –benzene, CO_2 –heptane, CO_2 –octane, CO_2 –nonane, CO_2 –decane, and CO_2 –undecane, were collected. The PR and PR-BM equations of state(EOS) in combination with relevant mixing rules were used to calculate the phase equilibrium data of the CO_2 –hydrocarbon binary mixtures. The binary interaction parameter k ij in the PR EOS was temperature independent, whereas parameters in the PR-BM EOS were functions of temperature. Thus, the phase equilibrium data and other thermodynamic properties of the binary and multicomponent mixtures at different temperatures and pressures can be calculated by using the parameters obtained in this work. The PR-BM EOS performed better than the PR EOS, and the average absolute deviations over the temperature range of 255.98–408.15 K calculated by the PR EOS and PR-BM EOS were less than 5.74% and 3.36%, respectively. The results calculated by the two EOS were compared with those calculated by other models, such as PPR78, PR + LCVM + UNIFAC, KIE + PR EOS + HV, and PSRK. The phase equilibrium data of CO_2 –butane–decane, CO_2 –hexane–decane, and CO_2 –octane–decane ternary mixtures were calculated by the two EOS. The average overall deviations for the CO_2 mole fractions calculated by the two EOS were less than 7.66%.     

非分析方法研究水-甲醇二元系的汽液相平衡

在101.325kPa下,用新型泵式沸点仪测定了水-甲醇二元系在不同液相组成时的沸点,并用非分析法由tpx推算了与之平衡的汽相组成y.用最小二乘法分别求出了甲醇-水二元体系的液相活度系数Wilson、NRTL、Margules和Van Laar模型参数,由这些模型参数推算的此二元系的泡点与实验值能很好的吻合.这些模型参数求得的结果,用面积检验法检验得到很好的热力学一致性.     

二元混合物相平衡和临界曲线的计算(英文)

利用一个从微扰理论出发得到的含有斥力项和引力项的状态方程计算６个二元系统的临界曲线,这些曲线一直延伸到很高的压力和温度．分子间力采用方阱模型,在势能计算的混合规则中仅需３个可调节参数．计算结果表明,运用状态方程预测的临界曲线、临界压力－组成关系以及摩尔体积与实验结果有很好的一致性．     

固体碱催化固定床法生产生物柴油的工艺研究(英文)

对固体碱催化剂催化固定床法工业化生产生物柴油进行了模拟.顺利进行了小试实验,并建立了生物柴油合成的酯交换反应的动力学模型,该模型能较为准确地描述酯交换反应.通过对文献中的气液平衡数据的回归得到了生物柴油的安托因方程.选择NRTL模型对脂肪酸甲酯(FAME)-甲醇-甘油体系进行描述,得到了体系NRTL的二组分参数,利用Aspen Plus对该体系液液平衡数据(LLE)的回归得到了三组分相图.为了预测固定床工艺生产在工业规模放大1 000倍后的效果,Aspen Plus对2个流程进行了仿真模拟,预测物料和能量消耗.模拟结果表明,与先前文献报道的数据相比,每小时生产每吨生物柴油至少可以减少350.42 kW的能量消耗.     

Vapour–Liquid Equilibrium for N,N-Dimethylformamide + Benzene + Thiophene via Gibbs Ensemble Molecular Simulation

The selection and design of an optimal solvent for extractive distillation require reliable vapour-liquid phase equilibrium data and knowledge of extraction mechanisms.Compared with time-consuming experiments,molecular simulation presents great potential in research on the properties of fluids.Therefore,in this work,Gibbs ensemble Monte Carlo was applied to successfully predict the vapour-liquid phase equilibrium data of binary and ternary systems containing benzene,thiophene and N,Ndimethylformamide(DMF) at P=101.3 kPa.The explicit hydrogen version of the transferable potentials for phase equilibria potential model was chosen for benzene and thiophene,whereas the OPLS potential model was selected for DMF.The predicted phase diagrams were compared with experimental data and the UNIQUAC thermodynamic model.A good agreement was obtained,which corroborated the validity of the potential models.In addition,the extraction mechanism was explored by radial distribution function(RDF) of the liquid-phase structure.The RDFs showed that thiophene and benzene shared a similar liquidphase structure because of the intermolecular interaction.The distinct difference between the RDFs of DMF/benzene and those of DMF/thiophene is that the oxygen atom of DMF is more associated with hydrogen atoms of thiophene than that of benzene,which may be responsible for the extraction effect of DMF.     

Calculation of gas-liquid critical curves for binary systems containing methane

The critical curves for binary systems of methane combined with nitrogen, carbon monoxide, carbon dioxide, ethane, propane, butane and water at temperatures from 125 K to 650 K and pressures from 3.5 MPa to 250 MPa were calculated by using Heilig-Franck equation of state. This equation of state contains a repulsion term and an attraction term for intermolecular interaction. With pairwise combination rules for these potentials, three adjustable parameters are needed. The results showed that the critical curves of the former six binary systems belonged to type I, and CH₄+H₂O system belonged to type III. The calculated data were compared with the experimental data, which yielded good results for the pressure-temperature, pressure-composition and temperature-composition behaviors of the seven systems. Moreover, the values of the adjustable parameters were obtained from the calculation of the critical curves. They can also be used for other relevant calculation.     

液体饱和蒸汽压测定实验的改进

针对目前静态法测定液体饱和蒸汽压实验中饱和蒸汽压数值读取不合理,汽液两相未充分平衡等问题,改变传统的调整U型管两端液面等高后再读取数字压力计的方法。改进后的实验装置只需在U型管的两侧标上刻度,待系统恒温、汽-液充分平衡后,读取数字压力计的数值、温度以及U型管两端液面的高度差就可得到该温度下的液体饱和蒸汽压。该方法可解决静态法测定液体饱和蒸汽压实验中调整U型管两端液面等高耗时,空气容易倒灌的问题。     

冷库制冷系统垂直上升回汽管液塞形成及消除

基于垂直上升立管汽液两相流型理论和冷负荷与压力(蒸发压力PZ、立管排液压力Pin)关系曲线两个角度,推理了制冷系统垂直上升回汽管内液塞形成过程,用于具体案例的液塞判断,并通过运行操作实践来消除液塞,由此验证推理和判断的合理性和适应性。分析了生产中加大压缩机载荷和热汽加压排液等措施的弊端,提出一种双罐轮流消除液塞的制冷工艺优化方案,可为液泵供液制冷系统工艺设计和运行管理提供指导。     

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 infinite-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 correlations for the vapor-liquid equilibria of non-polar and polar systems.     

Vapour–Liquid Equilibrium for <Emphasis Type="Italic">N</Emphasis>, <Emphasis Type="Italic">N</Emphasis>-Dimethylformamide + Benzene + Thiophene via Gibbs Ensemble Molecular Simulation

The selection and design of an optimal solvent for extractive distillation require reliable vapour–liquid phase equilibrium data and knowledge of extraction mechanisms. Compared with time-consuming experiments, molecular simulation presents great potential in research on the properties of fluids. Therefore, in this work, Gibbs ensemble Monte Carlo was applied to successfully predict the vapour–liquid phase equilibrium data of binary and ternary systems containing benzene, thiophene and N, N-dimethylformamide (DMF) at P = 101.3 kPa. The explicit hydrogen version of the transferable potentials for phase equilibria potential model was chosen for benzene and thiophene, whereas the OPLS potential model was selected for DMF. The predicted phase diagrams were compared with experimental data and the UNIQUAC thermodynamic model. A good agreement was obtained, which corroborated the validity of the potential models. In addition, the extraction mechanism was explored by radial distribution function (RDF) of the liquid-phase structure. The RDFs showed that thiophene and benzene shared a similar liquid-phase structure because of the intermolecular interaction. The distinct difference between the RDFs of DMF/benzene and those of DMF/thiophene is that the oxygen atom of DMF is more associated with hydrogen atoms of thiophene than that of benzene, which may be responsible for the extraction effect of DMF.     

基于扩展Miedema模型预测Zr-Al-Cu合金的非晶形成范围

为预测Zr-Al-Cu三元合金的非晶形成范围,运用扩展的Miedema模型计算了Zr-Al、Zr-Cu和Al-Cu二元合金的形成焓,结合Toop几何模型,并以Zr为非对称组元,计算了Zr-Al-Cu三元合金的形成焓值.计算结果表明,利用ΔHamor-ΔHss≤-2可以较好地预测该体系的非晶形成范围,而且预测的结果与实验结果能较好地吻合.     

卤代甲烷的沸点与分子结构之间的定量关系

探讨了卤代甲烷的沸点与其分子结构之间的关系 ,发展了一种既能计算卤代甲烷沸点、又能预测未知卤代甲烷沸点的方法 .对卤代甲烷的计算结果表明 ,沸点计算值与实验值的一致性令人满意 ,平均误差 1 75 % ,优于文献方法 .