Using a McCabe-Thiele diagram for a binary system, show why increasing \(\mathrm{N}\) may not be sufficient to keep purity constant compared to the base case if the diameter balancing method in Figure 10-17A (base case is a saturated vapor feed) or 10-18A (base case is a saturated liquid feed) is used to reduce the column volume. Although this demonstration is for a binary system, the logic is true for multicomponent systems also.

Figure 10-17A

A F, vapor