Pressure temperature diagram

In addition to the three principal polymorphs of siUca, three high pressure phases have been prepared keatite [17679-64-0] coesite, and stishovite. The pressure—temperature diagram in Figure 5 shows the approximate stabiUty relationships of coesite, quart2, tridymite, and cristobaUte. A number of other phases, eg, siUca O, siUca X, sihcaUte, and a cubic form derived from the mineral melanophlogite, have been identified (9), along with a stmcturaHy unique fibrous form, siUca W. 

Fig. 5. Pressure—temperature diagram for the more familiar Si02 polymorphs (43). To convert MPa to atm, divide by 0.101.

Pressure—temperature diagrams for the coesite—quart2 equilibrium have been summari2ed (23). Coesite has been found ia nature ia the meteor crater ia Ari2ona. 

Eig. 1. Schematic pressure—temperature diagram for a pure material showing the supercritical fluid region, where is the pure component critical point... 

Proved that the liquid vapour (L-V) equilibrium line in a one component system must always have a positive slope on a pressure-temperature diagram ... 

Fig. 6. Qualitative pressure—temperature diagrams depicting critical curves for the six types of phase behaviors for binary systems, where Ca or C corresponds to pure component critical point G, vapor L-, liquid U, upper critical end point and U, lower critical end point. Dashed curves are critical lines or phase boundaries (5). (a) Class I, the Ar—Kr system (b) Class II, the C02—C8H18 system (c) Class III, where the dashed lines A, B, C, and D correspond to the H2-CO, CH4-H2S, He-H2, and He-CH4 system, respectively (d) Class IV, the CH4 C6H16 system (e) Class V, the C2H6 C2H5OH...

Blockages of valves and pipes can also occur by gas hydrates. Such adducts can be formed by a number of gases with water. In Fig. 7.1-5 the pressure-temperature diagram of the system propane/water with an excess of propane is presented. The line, (g), shows the vapour-pressure curve of propane. Propane hydrate can be formed at temperatures below 5.3°C. At pressures below the vapor pressure of propane a phase of propane hydrate exists in equilibrium with propane gas (Fig. 7.1-5, area b). At higher pressures above the vapor pressure of propane and low temperatures a propane hydrate- and a liquid propane phase were found (area d). In order to exclude formation of gas hydrates these areas should be avoided handling wet propane and other compounds like ethylene, carbon dioxide [14], etc. 

Figure 7.1-5. Pressure-temperature diagram of the system propane/water [13]. a, Propane gas/water b, propane gas/propane hydrate c, propane liquid/water d, propane liquid/propane hydrate e, propane gas/ice f, hydrate curve g, vapor pressure curve of propane.

Use the data given in Figure 2-20 to prepare a pressure-temperature diagram of a 52.4 weight percent n-heptane in n-pentane mixture. 

FIGURE 4.2 Pressure-temperature diagrams, (a) Methane + water or nitrogen + water system in the hydrate region, (b) Hydrocarbon + water systems with upper quadruple points, (c) Multicomponent natural gas + water systems, (d) Hydrocarbon + water systems with upper quadruple points and inhibitors. 

Pressure-Temperature Diagrams for Multicomponent Natural Gas Systems... 

Pressure-Temperature Diagrams for Systems with Inhibitors... 

The pressure-temperature diagram for structure H has both similarities and differences from those diagrams shown above. Because the new hydrate was discovered... 

Figure 4.4 Pressure-temperature diagram for Xenon + Neo-hexane. (Reproduced from Makogon T.Y., Mehta, A.P., Sloan, E.D., J. Chem. Eng. Data, 41, 315 (1996). With permission from the American Chemical Society.)...

The projection of the three-dimensional surface on the pressure-temperature plane gives the familiar pressure-temperature diagram of a one component system. The projection for only the solid, liquid, and vapor phases... 

Figure 5. Pressure-temperature diagram for the naphthalene-CC system. and K are the critical points of pure carbon dioxide ana naphthalene, respectively. The...

Figure 12.6 Pressure/temperature diagram for the ethane/heptane system. (Reproduced by permission from F. H. Barr-David, AIChE 2 426, I9S6.)...

These data are represented5 m the pressure-temperature diagram (fig. 42) by the fusion curve AB, which is steep, but curved towards the abscissa,6 as the results in the last column of the above table clearly demand. This curve represents the equilibrium between ordinary ice or ice I and water, the triple point A representing the condition of equilibrium of water-vapour, liquid water, and ice I. Under a pressure of 2200 kilograms, corresponding to the point B in the figure, there is a break in the fusion curve, a new form of ice appearing, known as ice III,... 

Phi. 42.—The pressure-temperature diagram for water, ice, and water-vapour. 

Figure 2. Quantitave pressure-temperature diagram for carbon dioxide-water-1-propanol O, exp. ternary critical points, this work O four-phase equilibria, this work x four-phase equilibria, Fleck et al. [5]...

Pressure-temperature diagrams offer a useful way to depict the phase behaviour of multicomponent systems in a very condensed form. Here, they will be used to classify the phase behaviour of systems carbon dioxide-water-polar solvent, when the solvent is completely miscible with water. Unfortunately, pressure-temperature data on ternary critical points of these systems are scarcely published. Efremova and Shvarts [6,7] reported on results for such systems with methanol and ethanol as polar solvent, Wendland et al. [2,3] investigated such systems with acetone and isopropanol and Adrian et al. [4] measured critical points and phase equilibria of carbon dioxide-water-propionic acid. In addition, this work reports on the system with 1-propanol. The results can be classified into two groups. In systems behaving as described by pattern I, no four-phase equilibria are observed, whereas systems showing four-phase equilibria are designated by pattern II (cf. Figure 3). 

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