Hold plot feature

Figure 12.29 shows the fraction of and of as a function of stage number for the three-component separation example of Table 12.13. Characteristic features of this plot are as follows (1) The composition gradient is nearly linear on a semilog scale. This feature holds only for low- U and low- U fractions. (2) The composition gradient of is about two-thirds that of on a semilog scale. (3) The plot has a noticeable discontinuity in slope at the feed point and is noticeably curved upward in each section. (4) The content of the cascade at the feed point is substantially higher than the content of the feed. 

For non-reversible processes and those involving coupled chemical reactions Equation (6.56) wiU no longer hold however, Saveanl and coworkers [43-46] have derived similar linear plots of logarithmic functions of F t) as a function of E to enable kinetic parameters to be determined. Some examples of these functions are given in Table 6.9 others can be found in the literature. One important feature of all these functions is that they are independent of sweep rate, and therefore plots at various values of v ought to superimpose. This is a very useful test of whether the correct mechanism has been chosen. 

For mixtures, the pressure-volume plot differs from that of pure substances a schematic of a P-V plot for mixtures is shown in Fig. 3.5. The main differences between Figs. 3.4 and 3.5 are (1) and V of Fig. 3.5 do not represent the equilibrium states and (2) the critical points have different features. For a pure substance, (3P/3V ) = = 0 at the critical point. For a mixture, these two equations do not hold (see Figs. 3.1 and 3,5). The Z-factors in Fig. 3.4 of the equilibrium gas and liquid phases always meet the condition < Z. However, for mixtures, when gas and liquid phases are at equilibrium, Z might be smaller or larger than Z. At equilibrium, the mass density of the liquid phase is higher than the mass density of the gas phase,... 

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