Donald B. Robinson

Hydrate formation in systems containing methane, ethane, propane, carbon dioxide or hydrogen sulfide in the presence of methanol

Abstract Experimental measurements have been made on the initial hydrate formation temperatures and pressures in systems containing methane, ethane, propane, carbon dioxide or hydrogen sulfide in the presence of methanol solutions. The methanol solutions were varied from 5 to 20% by weight. The temperature range for hydrate formation was from about −10 to 17°C and the pressure range from 0.8 to 20 MPa. The results were compared with predictions made using the Hammerschmidt equation. Reasonably good agreement was found for the aqueous liquid—hydrate—gas region but poor agreement was found in the aqueous liquid—hydrate-former liquid—hydrate region.

The development of the Peng - Robinson equation and its application to phase equilibrium in a system containing methanol

Abstract The motivation for developing a cubic equation of state model having improved capabilities in the vicinity of the critical region and in predicting liquid densities is reviewed. The reliability of the resulting Peng-Robinson equation for predicting volumetric and phase behavior is illustrated for complex hydrocarbon systems. Modifications to improve the performance of the equation for two- and three-phase systems containing water are described. The reliability of the equation for system containing methanol is illustrated using new data on the methanol - carbon dioxide and methanol - propane systems. The agreement between experimental and calculated results is acceptable only over limited regions.

The equilibrium phase properties of (carbon dioxide + methanol)

Vapour and liquid equilibrium phase compositions were determined at the temperatures (323.2, 352.6, 394.2, and 477.6) K for (carbon dioxide + methanol). Measurements were made at pressures from the vapor pressure of the methanol to the critical region. Equilibrium ratios for each component were calculated at each temperature from the phase compositions. The critical temperatures and corresponding critical pressures were determined graphically and the critical locus was constructed for the binary mixture.

The phase behavior of two mixtures of methane, carbon dioxide, hydrogen sulfide, and water

Abstract The behavior of two mixtures of CH 4 , CO 2 , H 2 S and H 2 O was studied over a temperature range from ≈37.8° to 204°C at pressures in the 0.4–18.5 MPa range. The work was carried out to determine the composition of the equilibrium phases over a range of experimental conditions within the two- or three-phase envelope for each mixture, and to determine the two- and three-phase boundaries for each mixture within the temperature and pressure range of the study. A variable volume equilibrium cell consisting of a transparent sapphire cylinder was used for the experimental measurements and observations.

Three- and four-phase hydrate forming conditions in methane + isobutane + water

Abstract New results on the initial hydrate-formation conditions have been obtained for pure isobutane along the hydrate-water liquid-isobutane liquid locus and for 10 mixtures of methane and isobutane covering a composition range from 0.23 to 63.6 moles per cent of isobutane along the hydrate-water liquid-vapor locus. In addition the four-phase hydrate-water liquid-isobutane liquid-vapor quadruple locus has been determined from pure liquid and vapor phases. This occurred for a mixture containing 19.8 moles per cent of isobutane at a temperature of 298.6 K and a pressure of 11570 kPa. The phase behavior of systems of this type is described in some detail.

Equilibrium phase properties of the hydrogen—methane—carbon dioxide, hydrogen—carbon dioxide—n-pentane and hydrogen—n-pentane systems

Abstract The equilibrium vapor and liquid compositions and phase densities of two hydrogen-containing ternary systems and the hydrogen—n-pentane binary system were measured, and were used in conjunction with published pure - component refractivity data to calculate the molar volumes of each phase. Measurements for the hydrogen—methane—carbon dioxide ternary system were made at three isobars between 6900 and 20 700 kPa at −45.8°C, and at three isobars between 6900 and 27 600 kPa at −15°C. For the hydrogen—carbon dioxide—n-pentane ternary system, measurements were made at three isobars between 6900 and 27 600 kPa at 0 and at 50°C. The hydrogen—n-pentane data were measured at pressures up to 27 600 kPa at 0, 50 and 100°C. A new equilibrium cell, which was used in taking most of the data, is described in some detail.

The equilibrium phase properties of the methanol-hydrogen sulfide binary system

Abstract Leu, A.-D., Carroll, J.J. and Robinson, D.B., 1992. The equilibrium phase properties of the methanol-hydrogen sulfide binary system. Fluid Phase Equilibria, 72: 163-172. Vapor and liquid equilibrium phase compositions were determined at 25.0, 75.0, 125.0 and 175.0°C for the methanol-hydrogen sulfide system. Measurements were made at pressures from the vapor pressure of methanolto pressures in the critical region along each isotherm. Equilibrium ratios for each component were calculated from the phase composition data. The critical pressures and temperatures were determined for mixtures exhibiting the critical phenomena and a portion of the critical locus for the binary was constructed.

The equilibrium phase properties of selected naphthenic binary systems: Carbon dioxide-methylcyclohexane, hydrogen sulfide-methylcyclohexane

Abstract Vapor and liquid equilibrium phase compositions have been determined at temperatures ranging from 310 to 478 K for two binary systems. Measurements were made at 311.0, 338.9, 394.0, and 477.2 K for the carbon dioxide—methylcyclohexane system and at 310.9, 352.6, 394.3 and 477.6 K for the hydrogen sulfide—methylcyclohexane system. At each temperature, pressures ranged from the vapor pressure of methylcyclohexane to the vapor pressure of hydrogen sulfide, or to a pressure near the critical for the system, whichever was higher. The data were used to calculate equilibrium ratios for each component in the binary system.

Critical phenomena in a mixture of methane, carbon dioxide and hydrogen sulfide

Abstract Ng, H.-J., Robinson, D.B. and Leu, A.-D., 1985. Critical phenomena in a mixture of methane, carbon dioxide and hydrogen sulfide. Fluid Phase Equilibria , 19:273-286. The two- and three-phase boundaries for a mixture containing nominally 0.50 mole fraction methane, 0.10 mole fraction carbon dioxide and 0.40 mole fraction hydrogen sulfide were determined experimentally for a range of temperatures from c. 29 to – 83°C at pressures up to c. 13 MPa. The two-phase boundary curve commences with a conventional hydrogen-sulfide-rich liquid dew point locus which passes through an upper retrograde region and terminates at a vapor-hydrogen-sulfide-rich liquid critical point at − 16.9°C and 11.03 MPa. The phase boundary then follows a bubble point locus which terminates at a hydrogen-sulfide-rich liquid-methane-rich liquuid critical point at −45.6°C and 8.79 MPa. After this the boundary turns sharply upwards to higher pressures at lower temperatures. This separates the single phase from a second retrograde-like two-liquid region. The three-phase boundary enclosing a hydrogen-sulfide-rich liquid-methane-rich liquid—vapor region terminates when the methane-rich liquid dew point locus and the three-phase bubble point locus meet at a third critical point occurring at −57.5°C and 6.62 MPa. The measurements and observations were made using a sapphire cylinder as an equilibrium cell. Phase compositions and phase volume percentages were measured under a number of selected conditions in both the two- and three-phase regions.

Experimental measurement and prediction of hydrate forming conditions in the nitrogen-propane-water system

Abstract Experimental data on initial hydrate formation conditions have been obtained for the nitrogen-propane-water system in the L 1 HG , L 1 L 2 H , and L 1 L 2 HG regions, where L 1 is the water rich liquid phase, L 2 is the hydrocarbon rich liquid phase, H is the hydrate and the G is the vapor phase. The measurements covered a range of temperatures from about 275 to 293 K and pressures from about 0.3 to 17.0 MPa. The concentrations covered for the L 1 HG region extended from 0.94 to 75.0 mole percent propane in the gas phase, and for the L 1 L 2 H region they extended from 83.1 to 99.0 mole percent in the condensed liquid phase. Four-phase measurements were made at concentrations of propane from 18.1 to 71.1 mole percent in the gas phase. The experimental data were used to find a fitted binary interaction parameter for predicting hydrate formation in systems containing nitrogen and propane.