The area bounded by the bubble point and dew point curves on the phase diagram of a multicomponent mixture defines the conditions for gas and liquid to exist in equilibrium. This was discussed in Chapter 2. The quantities and compositions of the two phases vary at different points within the limits of this phase envelope. [Pg.347]

Referring to Fig. 2.1, at any point on the dew point curve the summation of each component divided by its respective K value at that point is equal to 1.0. Putting this statement in a mathematical term, [Pg.45]

Since in the critical point the bubble point curve (l+g—tf) and the dew-point curve (l+g-+g) merge at temperatures between 7C and 7 , an isotherm will intersect the dew-point curve twice. If we lower the pressure on this isotherm we will pass the first dew-point and with decreasing pressure the amount of liquid will increase. Then the amount of liquid will reach a maximum and upon a further decrease of the pressure the amount of liquid will decrease until is becomes zero at the second dew-point. The phenomenon is called retrograde condensation and is of importance for natural gas pipe lines. In supercritical extraction use is made of the opposite effect. With increasing pressure a non-volatile liquid will dissolve in a dense supercritical gas phase at the first dew point. [Pg.29]

Draw a p-T chart for water. Label the following clearly vapor-pressure curve, dew-point curve, saturated region, superheated region, subcooled region, and triple point. Show where evaporation, condensation, and sublimation take place by arrows. [Pg.297]

In areas surrounding the phase envelope, the system exists as a single phase. Below the dew point curve and at higher temperatures, it is a superheated vapor, while areas above the bubble point curve and to the left of it represent a sub-cooled liquid. In areas above the phase envelope between the sub-cooled liquid and the superheated vapor, the mixture is a dense or supercritical fluid, with properties changing gradually from those typical of a liquid to those typical of a vapor. [Pg.77]

The condition at which the liquid just begins to form is called the dew point. The condition at which the vapor just begins to form is called the bubble point. A curve can be plotted showing the temperature and pressure at which a mixture just begins to liquefy. Such a curve is called a dew-point curve or dew-point locus. A similar curve can be constructed for the bubble point. The phase envelope is the combined loci of the bubble and dew points, which intersect at a critical point. The phase envelope maps out the regions where the various phases exist. [Pg.73]

Figure 3.2 shows a phase envelope for an acid gas mixture. Note that the locus at lower pressure is the dew-point curve, whereas the one at higher pressure is the bubble-point curve. In fact, any point inside the phase envelope is a two-phase point. [Pg.73]

When the two components are mixed together (say in a mixture of 10% ethane, 90% n-heptane) the bubble point curve and the dew point curve no longer coincide, and a two-phase envelope appears. Within this two-phase region, a mixture of liquid and gas exist, with both components being present in each phase in proportions dictated by the exact temperature and pressure, i.e. the composition of the liquid and gas phases within the two-phase envelope are not constant. The mixture has its own critical point C g. [Pg.100]

Figure 10. Phase Diagram for Explaining the Difference between Analytical and Industrial Furfural Processes D and D Dew Point Curves E and E Boiling Point Curves |

In conventional vapor phase molecular sieve operations, the operating temperature must be even higher and the operating pressure must be even lower than that required by the dew point curve for the high boiling constituents. These extra requirements are needed to prevent capillary condensation. Condensa- [Pg.225]

Figure 3.3 Vapor-liquid equilibria of mixtures of cyclohexane and toluene (a) Txy diagram at a pressure of 1 atm, and (b) pxy diagram at a temperature of 50°C. The filled symbols denote the bubble point curves (saturated liquid), and the open symbols denote the dew point curves (saturated vapor). Data taken from F Rivenq, Bull. Soc. Chim. Fr. 9, 3034 (1969). |

In Fig. 3.3a, we present the Txy diagram for binary mixtures of cyclohexane and toluene at a pressure of 1 atm, which is below the critical pressure of both pure species. Point A denotes the boiling temperature of pure toluene, and point C is the boiling temperature of pure cyclohexane. Connecting these two points are two curves that form the two-phase envelope. The upper curve (with the open symbols) is the dew point curve, and the lower curve (with the filled symbols) is the bubble point line. [Pg.27]

Sometimes the liquid-vapor volume distribution in the two-pbaae region is also indicated on P-T diagrams. This can be accomplished by a series of curves each of which represents a certain percentage by volume of liquid. Thus the dotted curves XC, YC, and ZC represent 25%, 50%, and 75% by volume of liquid, respectively. In the isothermal compression described above, the point K would represent 50% liquid and 50% vapor by volume. Obviously, the dew-point curve and the bubble-point curve represent 0% and 100% liquid, respectively. [Pg.60]

If a mixture of benzene and toluene is heated in a vessel, closed in such a way that the pressure remains atmospheric and no material can escape and the mole fraction of the more volatile component in the liquid, that is benzene, is plotted as abscissa, and the temperature at which the mixture boils as ordinate, then the boiling curve is obtained as shown by ABCJ in Figure 11.5. The corresponding dew point curve ADEJ shows the temperature at which a vapour of composition y starts to condense. [Pg.544]

See also in sourсe #XX -- [ Pg.433 ]

See also in sourсe #XX -- [ Pg.85 ]

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