N_2，H_2，Ar在正辛醇中高压溶解度的测定

测定了温度范围在０～４５℃，压力达到８４．６×１０￣５ｐａ时，Ｎ＿２，Ｈ＿２，Ａｒ在正辛醇中的７５点高压气体溶解度数据，并提出一个由高压实验数据回归常压溶解度的方法。     

Solubility of isobutane and propane in polyethylene at high temperatures and low pressures

A novel procedure was developed to measure the solubility of isobutane and propane in both low and high-density polyethylene at temperatures to 500°F (260°C) and vapor pressures from 1 to 1500 torr (33 psia). These measurements represent the first known solubility measurements at these combined extremes of pressure and temperature. Excellent agreement was found when our data were extrapolated to higher pressures and compared with data from another source. In the temperature and pressure regions of interest in this work, the linear isotherms were fit with a form of the Flory–Huggins equation. With the equation in that form we can now estimate the ratio of solubilities of two solutes in a given polymer from pure solute data only. We can also predict the absolute solubility of nonpolar solutes in polyethylene at various temperatures and pressures using only critical temperatures and acentric factors of the solutes.     

Solubility and diffusivity of cyclohexane in high density polyethylene

The diffusivity and solubility of cyclohexane in a high density polyethylene, HDPE, were studied using a gravimetric, quartz‐spring, sorption balance. Solvent concentrations up to a weight fraction of 0.15 over a temperature range of 90 to 160°C were measured. Diffusion coefficients in the range of 10^?6 to 10^?7 were determined. Two types of polymer samples were used: a commercial bead form and flat sheets prepared by melting the polymer. Within the experimental error no differences were observed between the two forms indicating that there were no significant effects caused by the melting and compression. The solubility of cyclohexane in the HDPE as a function of the activity of the cyclohexane was linear. Above the melt temperature the solubility data were predicted better by the group‐contribution, lattice‐fluid equation of state (GCLF‐EoS) than by the van der Waals free‐volume (UNIFAC‐vdw‐FV) model. Below the melt temperature a correction factor for the elasticity significantly improved the predictions for both models. Although the HDPE has a crystallinity of 77.6%, the experimental data and the Vrentas‐Duda free‐volume theory indicated no significant tortuosity effects. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Solubility of methane in glycols at elevated pressures

The solubility of methane in ethylene glycol and in diethylene glycol has been determined at temperatures in the range 25 to 125 °C at pressures up to 20.4 MPa. The experimental results were correlated by the Peng-Robinson (1976) equation of state, and interaction parameters have been obtained for these systems. Henry's constants were derived for comparison with data from the literature.     

高压氮气在正庚烷中溶解度的数学模型

采用R-K状态方程和正规溶液理论推导出高压氮气在正庚烷中的溶解度模型为lnX=lnP B1P B2P2 B3,并通过实验测定了其理论模型参数分别为:B1=-2.64 8.92×10-3T-5.06×10-6T2,B2=3.61×10-2 6.91×10-4T-2.18×10-6T2,B3=3.92-3.92×10-2T 5.20×10-5T2;在温度0~100℃与压力0~12 MPa范围内,经实验验证该模型计算值与实测数据平均相对偏差为-3.6%,因此该模型可以作为高压氮气在正庚烷中溶解度的适宜计算公式。     

固体在超临界二氧化碳中溶解度的关联与计算

精确的溶解度数据是超临界流体萃取工艺设备设计和操作条件选择的关键 ,本文采用Peng -Robinson状态方程对 15种固体在超临界CO2 中的溶解度数据进行了关联计算 ,溶解度的计算值与文献的实验值符合很好 ,其平均相对偏差均小于 10 %。     

A single crystal of polyethylene crystallized under high pressure

A single crystal of polyethylene about 2 μm thick has for the first time been obtained through high pressure crystallization and studied by X-ray diffraction and scanning electron microscopy. A band of a few μm thickness observed on the fractured surface of high pressure crystallized polyethylene is identified as a single crystal at least several tens of μm wide. Furthermore, a bulk composed of several bands stacked approximately parallel gives hexagonal symmetry in an X-ray oscillation photograph, the oscillation axis being parallel to the end surface of the bands. On the basis of these observations, it is concluded that a thick single crystal in the hexagonal phase splits into several bands on the transition from the hexagonal to the orthorhombic phase; 〈110〉 or 〈010〉 of each band in the orthorhombic phase corresponds to one of three possible a-axes in the hexagonal phase.     

Solubility study for the purification of hydrogen from high pressure hydrocracker off-gas by an absorption-stripping process

Experiments were carried out to identify a solvent which has a high solubility and selectivity for methane relative to hydrogen at 295 K and pressures from 13.88 to 20.78 MPa. Binary solubilities with pure hydrogen and methane, and ternary solubilities with 73 mol% H₂ and 27 mol% CH₄ were measured at 295 K and for pressures from 6.99 to 20.78 MPa in various organic solvents. This gas mixture simulates hydrocracker and hydrotreater off-gases which are candidates for purification with an absorption-stripper. Of the solvents tested, 2,2,4-trimethylpentane (iso-octane), which showed very high methane solubility and a reasonable selectivity, and methylcyclohexane, which showed a very high selectivity and a reasonable solubility, are the best solvents for methane absorption. Correlations for hydrogen and methane as a function of pressure and solvent solubility parameter were developed with the experimental solubilities. Binary interaction parameters for Peng-Robinson (Peng and Robinson, 1976) and Soave-Redlich-Kwong (Soave, 1972) equations of state were calculated with experimental solubility results. Prediction of gas solubility in a ternary system was compared with experimental and found to be satisfactory when experimental binary interaction parameters were used.     

阿昔洛韦在超临界CO2中的溶解度与关联

药物微粒化可改善其溶出度,提高生物利用度。为应用超临界流体技术制备阿昔洛韦(Acyclovir)微粒,用静态法测定了在313．15～413．15K,10．0～30．0MPa下阿昔洛韦在超临界CO2中的溶解度。阿昔洛韦的溶解度较小,在10^-5～10^-7(摩尔分率)之间,溶解度随着温度和压力的升高而增大,不存在文献报道的反向区。采用P-R方程对溶解度数据进行关联,平均相对误差为10．0％。     

Laboratory testing of dispersant effectiveness at high pressures

Oil spills remain a serious environmental problem, and can have significant economic and ecological consequences. Despite the advantages, accidental deep-sea oil releases during offshore exploration or production activities are of particular concern as the potential for such incidents increases significantly as we move to deeper waters. Dispersants are important mitigation tools as they have the capability to disperse the oil into a cloud of tiny oil droplets that can be readily degraded by hydrocarbon degraders if suitable environmental conditions prevail. In the case of an offshore incident, the dispersant is injected near the point of crude oil release so that dispersion is more effective. Given that our experience with subsea dispersant use is limited, the effect of pressure on the effectiveness of the dispersant has not been established, and hence, the composition and amount of dispersant to be injected has not been optimized. For typical surface oil spills, dispersant effectiveness is experimentally measured under laboratory conditions by the US-Environmental Protection Agency (EPA) baffled flask test, which was later adapted as ASTM standard method F3251. Despite its extended use, this test cannot be used for testing dispersants at elevated pressures. In order to see whether pressure affects dispersant effectiveness, we developed a simple laboratory test protocol using a high-pressure reactor (HPR). In addition, the effectiveness of five commercially available dispersants (COREXIT™ EC9500A, COREXIT™ EC9500B and COREXIT™ EC9527A, Marichem™, and Oiler 60) applied to a dead light crude oil has been determined at various pressures for the first time, and these values have been related to the standard baffled flask test (BFT) at atmospheric pressure. It is shown that pressure increase adversely affects dispersant effectiveness; however, the effect varies from a few percent to nearly a 50% decrease for a pressure increase of 100 bar depending on the particular dispersant used.     

超临界水中硫酸钠溶解度研究

研究硫酸钠在超临界水中的溶解度。在实验范围内 (4 0 0 5 0 0℃ ,2 2 .5 30MPa)测得溶解度均小于40× 10 -6g/g。随温度降低和压力升高 ,硫酸钠溶解度增大。关联了溶解度模型 ,表明同一温度下的硫酸钠溶解度对数与水密度对数呈线性关系。     

溶解度参数法计算超临界流体的溶解度

溶质在超临界流体中的溶解度计算方法有热力学模型和经验公式2种,其中经验公式法形式简单,精度接近甚至高于热力学模型,应用广泛。以往的经验公式多用超临界流体密度来关联溶解度,文中选择以溶解度参数为变量,用3个与温度无关的可调参数,建立了超临界流体溶解度计算的经验公式。计算的11种固体在超临界CO2、乙烷和乙烯中溶解度与实验数据的平均相对误差在10%左右。与密度相比,溶剂与溶质的溶解度参数差更能直观地反映出超临界流体对物质的溶解能力,且具有明确的理论基础,应该引起足够的重视和推广。     

A practical equation of state for non‐spherical and asymmetric systems for application at high pressures. Part 2: Extension to mixtures

In part I of this series the pure component PHCT‐DNSK equation of state (EOS) was presented. In this paper the EOS is extended to describe mixtures, particularly asymmetric mixtures containing one or more low molecular weight spherical compound together with one or more high molecular weight chain‐like compound. The EOS utilises theoretically correct mixing rules and is generally able to predict the correct trends quantitatively for binary mixtures, and in most cases outperform other EOSs. With the use of a small, temperature independent, interaction parameter the EOS is able to predict the phase behaviour of the investigated systems qualitatively. The EOS is able to predict the phase behaviour of a multi‐component system containing one or more light components and a range of heavy hydrocarbons with improved accuracy compared to other EOSs at reduced computational times. © 2011 Canadian Society for Chemical Engineering     

我国高密度聚乙烯进口情况分析

从高密度聚乙烯(HDPE)的进口量、贸易方式、进口来源和价格等方面分析了我国近几年HDPE的进口情况和变化趋势。我国HDPE的进口量呈快速增长态势。在不同贸易方式中,以一般贸易方式进口HDPE为主,且每月进口HDPE的量波动很大;从进口来源上看,中东国家对我国的出口量增长很快。我国进口HDPE品种全且牌号多,涉及到HDPE应用的各个方面;从中东和东南亚等低成本地区主要进口通用型牌号,而从欧洲、日本、韩国和美国等主要进口高附加值产品。最后,对我国HDPE生产企业提出了相关建议。     

Nitrogen solubilities in low-density polyethylene at high temperatures and high pressures

An apparatus for the determination of the solubility of gases in polymers at high pressure and high temperature is described. The solubilities of nitrogen in low-density polyethylene (PE800E) at 394–450 K at pressures between 10 and 125 atm are reported. Empirical correlations are obtained which represent the Flory–Huggins interaction parameter χ, solubility coefficient K_H, and activity coefficient of dissolved gas Ω₂ as functions of temperature and pressure for the above system. © 1995 John Wiley & Sons, Inc.     

Anomalous heat capacity of high‐density polyethylene melts at high temperature

The first measurements of heat capacity of high‐density polyethylene have been obtained for melts in the high‐temperature region of 180–260°C. A heat‐flow twin calorimeter was used. Abrupt transitions are noticed at 212 and 228°C, analogous to transitions seen earlier with rheological and surface tension measurements. Possible explanations for these phenomena are offered. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A practical equation of state for non‐spherical and asymmetric systems for application at high pressures. Part 1: Development of the pure component model

A practical, mathematically and computationally simple, equation of state (EOS) has been developed to accurately describe pure component phase behaviour of spherical and chain‐like molecules. The EOS consists of a newly developed hard sphere model and a perturbation term based on the Barker and Henderson approach using the Chen and Kreglewski intermolecular potential model and a double constrained summation as a mathematical expression thereof. The perturbed hard chain theory (PHCT) approach is used to extend the EOS to non‐spherical molecules. The EOS compares well with other more complex models such as the simplified perturbed hard chain theory (SPHCT) and statistically associating fluid theory (SAFT) models and will be extended to describe mixtures in Part 2 of this series. © 2011 Canadian Society for Chemical Engineering     

高温下对苯二甲酸在醋酸-水溶液中的溶解度预测

在醋酸摩尔分数0.73,温度130～270℃的范围内利用UNIFAC模型估算了对苯二甲酸在醋酸 水溶液中的溶解度,估算值与文献值的平均相对误差7.74%,表明本文所建方法在缺乏实验数据的情况下可以用来预测高温下TA在醋酸 水溶液中的溶解度。因此,用该方法预测了130～270℃范围内60%～90%醋酸 水溶液中的TA的溶解度,给出了不同组成下的溶解度 温度图。     

Solubility of fatty acids in supercritical carbon dioxide

The solubilities of lauric, linoleic, myristic, oleic, palmitic and stearic acid in supercritical carbon dioxide (SC-CO₂) at different pressures and temperatures were measured. The solubility values obtained in this work were compared with previously published data, and possible causes for observed discrepancies were discussed. The solubilities of the six fatty acids were modeled by Chrastil’s equation, and estimated model parameters were used to plot the solubility isotherms of fatty acids at 313, 323 and 333°K (40, 50 and 60°C) as a function of SC-CO₂ density. The comparison of solubility isotherms of fatty acids and vegetable oil suggests that separation of fatty acids from triglycerides might be possible by using SC-CO₂ at densities less than 700 kg/m³. From the effect of temperature on fatty-acid and vegetable-oil solubility, it seems that the extraction yield could be increased without sacrificing the selectivity of SC-CO₂ for fatty acids by choosing a higher operating temperature. The data also suggest that fractionation of certain fatty acids might be possible by manipulating the processing conditions. Given the values of the constants, Chrastil’s equation could serve as a guideline for choosing appropriate processing conditions and predicting the effect of pressure and temperature of SC-CO₂ on solute solubility.     

Solubility / retention relationships in supercritical-fluid chromatography

The effects of temperature, pressure and supercritical fluid density on solubility-retention relationship of solutes in supercritical fluid partition chromatography are investigated. New retention data for naphthalene and phenanthrene are obtained as a function of pressure at different temperatures. The mobile-phase partial molar volumes of the solutes are determined from infinite-dilution fugacity coefficients and used to model the pressure dependence of solute retention that reveals the nature of interactions between the stationary phase and the solute. Relationships between pressure and temperature dependence of solubility and retention of solutes are also illustrated.