Vapour-liquid and vapour-liquid-liquid equilibria in ternary and quaternary systems of n-hexadecane,benzene, water and hydrogen,at elevated temperatures and pressures

Phase equilibria in the n-hexadecane-water-hydrogen and n-hexadecane-benzene-water-hydrogen systems were determined experimentally at temperatures between 200 and 350°C and pressures between 100 and 300 bar. At high water concentrations, three-phase equilibria were observed. Two-phase regions could be correlated with a modified Redlich-Kwong equation of state. The influence of interaction parameters on the calculated miscibility gaps was investigated. On application of mean interaction parameters, it is possible to calculate phase equilibria at different pressures or temperatures with the same set of parameters. In the ternary system, the three-phase regions could be calculated from the correlated binodal curves of two-phase regions. In the quaternary system, cross-sections through the vapour-liquid miscibility gap could be successfully correlated.     

Stability of acetylene/methane and acetylene/hydrogen/methane gas mixtures at elevated temperatures and pressures

Hydrogen-enriched natural gas (HENG) containing a mixture of acetylene, hydrogen, and methane is produced from natural gas feedstock in our plasma dissociation process. Storage of this HENG fuel at pressures up to 4000 psig is required for rapid vehicle refueling. Little information on the stability of acetylene mixtures at elevated pressures is presently available; therefore we have performed stability testing on gas mixtures that simulate our HENG fuel. This report describes the stability testing of binary gas mixtures of acetylene and methane containing up to 10%(v) acetylene, and a ternary gas mixture of 4%(v) acetylene, 20%(v) hydrogen, and 76%(v) methane, at pressures up to 3600 psig and temperatures up to 200 °C. The mixtures tested were found to be stable to rapid spontaneous decomposition at all test conditions; however, some degree of hydrogenation of acetylene to ethylene may have occurred in an intermediate mixture of acetylene and hydrogen while preparing the highest pressure ternary test mixture.     

Hydrogen mass transfer in liquid hydrocarbons at elevated temperatures and pressures

The mass transfer rate of hydrogen in tetralin and hydrogenated SRC II liquid was studied in a stirred vessel at 606–684 K and 7.0–13.5 MPa. Experiments were carried out using a newly developed in-situ hydrogen probe made of semi-permeable nickel membrane. The effects of stirrer speed, liquid height to vessel diameter ratio, temperature and pressure on mass transfer rate coefficients were investigated. The experimentally determined $\text{K}{}_{\mathrm{<mtext>l</mtext>}}\text{a}$ values were correlated in terms of power input per unit volume of liquid and liquid height to vessel diameter ratio as follows: $\text{k}{}_{\mathrm{<mtext>L</mtext>}}\text{a = 3.43 × 10}{}^{\mathrm{?4}}\text{(}\text{P}\text{V}\text{)}{}^{0.8}\text{(}\text{H}\text{D}{}_{\mathrm{<mtext>T</mtext>}}\text{)}{}^{\mathrm{?1.9}}$ Furthermore, the liquid-phase mass transfer coefficient, $\text{k}{}_{\mathrm{<mtext>l</mtext>}}$, was found to be of the order of 10^?5 m s^?1 for low agitator speeds.     

The role of hydrogen in coal particle disintegration at elevated temperatures

Coal particle size is considered to be a variable of secondary importance in coal/oil co-processing and coal liquefaction. This finding is inconsistent with the proposed mechanism for coal particle disintegration, and product yields realized in previous large scale dissolution experiments. Coal particles are shown to break up as a consequence of hydrogen-coal interactions occurring during preheating. The proposed mechano-chemical mechanism for coal particle disintegration was identified through direct observation of disintegrating coal particles at elevated temperatures and pressures. Implications for the design of preheaters for coal/oil co-processing and coal liquefaction are discussed.     

Minimum fluidization velocity at elevated temperatures and pressures

A procedure based on the Ergun equation to predict the minimum fluidization velocity at elevated temperatures and pressures and for different gaseous fluidizing agents has been discussed and shown to be applicable for practical purposes.     

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.     

Activated diffusion of methane from coals at elevated pressures

Diffusion of methane from three coals ranging in rank from anthracite to HVA bituminous has been studied at initial methane pressures up to about 2.76 MPa (400 psi). Unsteady-state diffusion conditions existed, the methane pressure within the coal particle decreasing with time while the methane pressure outside the particles remained at atmospheric. The diffusion parameter $\text{D}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{r}{}_0$ increased with increasing methane concentration at high values of methane sorption. Diffusion was activated but the exact magnitude of the activation energy is uncertain owing to the suspected contribution of the heat of sorption to the temperature coefficient. $\text{D}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{r}{}_0$ increased with decreasing particle size of coal studied, but r₀ is clearly less than the particle radius.     

Kinetics of coal char gasification at elevated pressures

The effects of temperature, pressure, steam flow rate and CO₂/H₂O ratio of gasifying agent on the pressurized gasification of Linnancang coal char were investigated. A correlation of kinetic data was developed for coal chars from coals of different ranks at 30 kg cm ⁻² and 950 °C. The catalytic effects of Ca, Na and Fe catalysts on the gasification activity, activation energy and methane recovery were studied.     

Vapour-liquid equilibria for the systems: Methylcyclohexane-n-butanol and toluene-n-butanol

Isobaric and isothermal vapour-liquid equilibria have been determined for the binary systems: methylcyclohexane-n-butanol and toluene-n-butanol at 760 mm Hg total pressure and 90° using a modified Colburn still. The activity coefficients data were satisfactorily tested for their thermodynamic consistency by the method of Herington and a satisfactory correlation was also obtained through Wohl's three-suffix Margules equations for both conditions of restraint in the case of both systems. Azeotropes were observed for both systems and both conditions of restraint.     

煤炭直接液化体系高温高压气液相平衡研究进展及模型选择

笔者从气液相平衡基础理论展开并综述了高温高压相平衡计算研究进展，介绍了状态方程法、混合模型法、超额Gibbs自由能-状态方程模型法，并重点介绍了超额Gibbs自由能-状态方程模型法的思路及应用特点。针对煤炭直接液化物系高温、高压、强不对称、强极性、完全非理想体系等特点，与结合传统混合规则的状态方程法及混合模型法相比较，采用超额Gibbs自由能-状态方程模型法能够在更大范围内准确计算和预测煤液化气液相平衡。     

Solvent extraction of fatty acids from natural oils with liquid water at elevated temperatures and pressures

The use of liquid water at elevated temperatures and pressures as an extractive solvent for separating mixtures of compounds which occur in natural oils has been studied. A southern pine tall oil and a distillate from the deodorization of soybean oil were extracted with liquid water at temperatures from 298 to 312°C and pressures between 103 and 121 bar. Results indicate that water can be used to extract fatty and resin acids from crude tall oil to obtain a product with a high acid content that produces less pitch during distillation. The process can also be used to extract fatty acids from vegetable oil deodorizer distillate.     

Viscosity of coal tar pitch at elevated temperatures

At temperatures up to about 200 ° the viscosity of pitch, of approximately 100 °C Ring and Ball Softening Point, follows a predictable variation with temperature. Above 200 °C, variations occur depending on the source of the pitch, although a minimum viscosity is always achieved between 320 and 400 °C, followed by a rise. On heat treating at a constant temperature of 400 °C the viscosity rises. Although some preliminary work on two low-temperature pitches indicates a different regime, the work on coke-oven pitches shows a clear relation between viscosity rise and the formation of toluene- and quinoline-insolubles by what appears to be consecutive reactions from tar oils, during which the rheological behaviour becomes increasingly pseudoplastic.     

Vapor-liquid equilibria of carbon dioxide and nonionic surfactant system at elevated pressures

Aqueous solutions of the polyoxyethylene nonionic amphiphiles have been extensively investigated at atmospheric pressure, but only a few data of nonionic amphiphile — carbon dioxide system are available at elevated pressures. Isothermal vapor-liquid equilibrium data for the binary ethylene glycol propyl ether (C3E1) — carbon dioxide system at 313.15 K, 323.15 K were measured at elevated pressures. We used two-phase circulating type equipment with a view cell. Modeling of the experimental data has been performed using the Peng-Robinson equation of state, statistical associating fluid theory (SAFT) and Sanchez-Lacombe equation of state.     

Adsorption of methane/ethane mixtures on dry coal at elevated pressure

The binary adsorption characteristics of methane and ethane on dry coal to 40 atm pressure have been calculated from pure-component isotherms. In some coal seams, pressures exceeding 40 atm have been recorded and the methane sampled from the virgin coal often shows a few percent of ethane. The binary adsorption characteristics were calculated by employing the ideal adsorbed solution theory of Myers and Prausnitz, and experimentally-determined (Type I) pure gas isotherms at 0, 30 and 50 °C. The coal used in this investigation was high-volatile ‘A’ bituminous (hvab) from the Pennsylvania Pittsburgh seam. Gas nonideality was accounted for by replacing pressure with fugacity. Adsorption of methane on dry coal is purely physical; the isosteric heat of adsorption does not exceed 2.4 kcal/mol^* at 30 °C on the above coal. Isobars on the resulting binary equilibrium diagram exhibited an unexpected phenomenon of intersecting each other which might be attributable to the above nonideality considerations. The region of a few percent of ethane, which is of practical importance from the viewpoint of coal seams, was expanded and reduced to an equation: V(CH₄) = −21.52 + 7.18(VF) + 16.88(VF)² −0.395(P) − 0.00661(P)² + 0.824(T) − 0.00030(T)² + 0.928(VF)(P) − 0.858(VF)(T). V(Total) = 25.9 − 23.6(VF) + 0.655(P) − 0.00875(P)² − 0.795(T) + 0.743(VF)(T) where V(CH₄) and V(Total) = cm³(STP)CH₄ and total gas respectively adsorbed per g dry coal; VF = vol. fraction of methane as analysed at 1 atm (0.94 VF 1.0); P = seam pressure, atm (0 P 40); T=seam temperature, °C(−10 T 50).     

Adsorption of methane on dry coal at elevated pressure

Methane equilibrium adsorption isotherms were determined on Illinois No.6 (Herrin seam), Oklahoma Hartshorne, Pennsylvania Pittsburgh, and Virginia Pocahontas No.3 United States coal seams, using a volumetric method and an equation of state for methane: the amount of methane adsorbed on crushed and dried coal was measured as a function of pressure. Isotherms were measured at 30 °C for the Illinois coal and at 0, 30 and 50 °C for the others. Most measurements were made to 150 atm pressure, but a few to 240 atm. The data were correlated by the Langmuir and the Polanyi adsorption models. The methane—coal system, uncorrected for adsorbate density, adhered well to the Langmuir model up to 150 atm pressure, but Polanyi behaviour could not be demonstrated satisfactorily, with or without a correction for adsorbate density. Monolayer volumes at 30 °C from the Langmuir equation were 28, 24, 19 and 20cm³ (STP)/g coal respectively for the four coals studied (the range for several investigators was 13 to 39 cm³/g and for the Langmuir constant b 0.03 to 0.23 atm^?1). Isosteric heats of adsorption at zero coverage and 30 °C were 4.2, 2.4 and 5.3 kcal/mol for the Hartshorne, Pittsburgh and Pocahontas coals, which indicate that the adsorption is physical. No effect of particle size on equilibrium adsorption was observed in the U.S. mesh range 6–325.     

An experimental investigation of minimum fluidization velocity at elevated temperatures and pressures

Minimum fluidization data at elevated temperatures and pressures are relatively scarce in the literature. This study was undertaken to provide some new data under these conditions. Minimum fluidization velocities at temperatures up to 800°K and pressures up to 5 MPa were measured for uniformly-sized glass beads with diameters between 0.2 mm and 4 mm in beds ranging in diameter from 30 mm to 50 mm. The experimental results are compared with a number of empirical correlations from the literature to determine the validity of the correlations under these elevated temperature and pressure conditions.     

Viscosity of organic liquids at elevated temperatures and the corresponding vapour pressures

This work involved the measurement of the viscosities of pure organic liquids at temperatures ranging from 353.15 K to 463.15 K and at the corresponding vapour pressures. A rolling ball viscometer was used where considerable emphasis was given to achieve simplicity and rapidity in obtaining results, without sacrificing the accuracy. Considering the forces affecting the motion of the ball inside the viscometer tube, an equation for the calibration of the viscometer at the same working temperature was derived. The constants of this equation were determined using benzene as the reference liquid, and the dependency of the constants on the temperature was also established. Comparing the derived equation with published ones demonstrated its adequacy in both the streamline and transition flow conditions. The liquids studied were toluene, methanol and n-hexane. In some cases, the results compared reasonably well with published data while in others, deviations of up to 15% were found. Nine equations were tested with the experimental results for the prediction of the viscosity of these liquids. It was found that the 3-constant Agrawal and Thodos empirical equation gave the least average deviation.     

Saturated thermodynamic properties for the air-water system at elevated temperatures and pressures

A new thermodynamic model is proposed to calculate the thermodynamic properties for the air-water system in which the dry air was assumed to be a mixture of nitrogen and oxygen with the mole fractions of 0.7812 and 0.2188, respectively. For the vapor phase, fugacity coefficients were calculated with the modified Redlich-Kwong equation of state in which a new interaction parameter of oxygen and water was correlated from the experimental data of oxygen-water system. The dissolved gas followed Henry's law. Henry's constant of nitrogen was calculated with the Helgeson equation of state and that for oxygen was correlated from the experimental data of oxygen-water system. The proposed model was verified by comparing the calculated results with the available experimental data. It is shown that the proposed model is suitable for predicting saturated thermodynamic properties for the air-water system up to 300°C and . Furthermore, the prediction results of the proposed model are better than those calculated with the model of Rabinovich and Beketov (Moist Gases, Thermodynamic Properties. Begell: House, 1995), and the application range is wider than that of the model of Hyland and Wexler (ASHRAE Trans. 89(2A) (1983a, b) 500-519, 520-535) which are among the best of today's models.     

Raman and infrared spectroscopic study of kerogen treated at elevated temperatures and pressures

Kerogen was treated for 24 h at temperatures of 250–700 °C and pressures of 500–1500 bar. Raman spectroscopic study of the run products documented systematic changes in both the first- and second-order spectral features with temperature and pressure. The micro-FTIR analysis of the kerogen treated showed that the presence of hydrogenated functional groups and importance of aromatic rings in the structures of the kerogen increased with temperature. An abrupt change in the chemical composition and structural state of the kerogen treated occurred at ∼500 °C.     

Catalytic partial “oxidation of methane to syngas” at elevated pressures

In this work we demonstrate catalytic partial oxidation of methane into syngas at pressures up to 0.8 MPa, power densities up to 15 MW/L and selectivity greater than 85%. The product composition profiles indicate high initial selectivity to CO and low initial selectivity to H₂, suggesting direct partial Oxidation of methane primarily into CO and water, while most hydrogen is produced in the consecutive steam reforming of methane.