These values are plotted in Fig. 5.5o.
As discussed in the problem statement, it is possible that the P recovered from the distillation could be sold, thus it is desirable to recover P in a state of reasonably high purity (say, 0.98 mole fraction). Therefore, drawing a line joining 0.98 distillate composition and the vapor composition in equilibrium with the feed in Fig. 5.5a produces a y intercept of 0.647. Therefore, minimum reflux ratio is, from Eq. (5.20)
yint 0.647
Selecting a reasonable actual reflux ratio (say, 1.3 x ,ยก,'1
Drawing a line connecting this point with xD in Fig. 5.56 and stepping off theoretical stages shows that only three stages are required.
Mole fraction, P in liquid (b)
Figure 5.5 Separation of P from R in case history. (a-f) McCabe-Thiele diagram, <* = 30.8, for separation at progressively higher reflux ratios.
Mole fraction, P in liquid (b)
Figure 5.5 Separation of P from R in case history. (a-f) McCabe-Thiele diagram, <* = 30.8, for separation at progressively higher reflux ratios.
Figura 5.5 (Continued) Separation of P from R in case history. ia-f) McCabe-Thiele diagram, a = 30.8, for separation at progressively higher reflux ratios.
Mole fraction, P in liquid (')
Figure 5.5 (Continued) Separation of P from R in case history. a-f) McCabe-Tbiele diagram, a = 30.8, for separation at progressively higher reflux ratios.
Mole fraction, P in liquid (')
Figure 5.5 (Continued) Separation of P from R in case history. a-f) McCabe-Tbiele diagram, a = 30.8, for separation at progressively higher reflux ratios.
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