Diagrams For Binary Systems

To analyze a given two-component system, a physical property model must be selected. Aspen Physical Property System has a large number of built-in binary parameters for a number of models. The Txy, yx, and other binary plots can easily be generated in Aspen with the calculation of the phase equilibrium relationship all hidden. 

At the bottom of the window showing binary analysis results, you can click Plot Wizard to generate a yx plot or other plots such as activity coefficient or K value versus mole fraction. The predicted Txy and yx plots by the model can be compared to the experimental data in the literature so that you can have confidence using the Aspen built-in parameters in 

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At first sight there is a problem in drawing phase diagrams for binary systems there are three state variables (p, T and Xg). 

For our purposes, there are shortcut equations or it is fairly easy to produce a McCabe-Thiele diagram for binary systems. It helps to have a rough feel for the answer even if a computer program is to be run. For many splits, a McCabe-Thiele diagram is a real help in seeing how the system behaves. 

Figure 15.4. Phase diagrams for binary systems (E - eutectic, L - liquid)...

Hgure 1.6 Common types of equilibrium diagrams for binary systems. (From J, R Fair. Distillation, in R, W, Rousseau, Handbook of Separation Process Technology, copyright 1987 by John Wiley Sons, New York. Reprinted by permission of John Wiley 4 Sons Inc.)... 

Figure 6 is selected using the classification by Scott Konijnenburg (7), which describes only six different basic types of phase diagrams for binary systems. In Figure 4 a minimum can be observed at high pressure in the 70wt% fat isopleth, which corresponds to convergence of the isotherms in Figure 5. This is a clear indication of type III phase behavior, which is represented in Figure 6. A liquid-liquid phase split is in general typical for a type III system (9).

FIGURE 5.2-5 Common types of equilibrium diagrams for binary systems. 

Figure 5.2-5 shows equilibrium diagrams for binary systems containing maximum boiling (acetone-chlorofotm) and nunimum boiling (ethanol-water) azeotropes. It also shows an example of an azeotrope which, when condensed, forms two liquid phases (n-butanol-water) this is called a heterogeneous azeotrope. 

Figure 1-43 shows characteristic diagrams for binary systems with explanations given in the caption. 

We shall consider in detail some versions of p-V-T-x curve methods using schemes of typical isothermal and isobaric sections (Figure 1.10) of phase diagrams for binary systems. 

To obtain die systematic classification of complete phase diagrams for binary systems the method of continuous topological transformation was used (Valyashko, 1990a,b 2002a,b). This method is based on the following two main principles ... 

Similarly to the phase diagrams for binary systems, the main types for fluid phase diagrams of ternary mixtures should not have an intersection of critical curves and inunis-cibUity regions with a crystallization surface in them. Combination of four main types of binary fluid phase behavior la, lb, Ic and Id (Figure 1.2) for constituting binary subsystems gives six major classes of ternary fluid mixtures with one volatile component, two binary subsystems (with volatile component) complicated by the immiscibility phenomena and the third binary subsystem (consisted from two nonvolatile components) of type la with a continuous solid solutions. These six classes of ternary fluid mixtures can be referred as ternary class I (with binary subsystems Ib-lb-la), ternary class II (with binary subsystems Ic-lc-la), ternary class III (with binary subsystems Id-ld-la), or ternary class IV (with binary subsystems Ib-ld-la), ternary class V (with binary subsystems Ib-lc-la) and ternary class VI (with binary subsystems Ic-ld-la). 

Construct phase diagrams for binary systems in vapor-liquid equilibria (VLE), liquid-liquid equilibria (LLE), vapor-liquid-liquid equilibria (VLLE), solid-liquid equilibria (SLE), solid-solid equilibria (SSE), and solid-solid-liquid equilibria (SSLE), correcting for nonideal behavior in the vapor, liquid, or solid phases using fugacity coefficients and activity coefficients. 

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