Bow-Tie Regions

FKiURE 2.13 Bow tie region bounded by the direct and indirect mass balance lines for the benzene// xylene/toluene system at P = 1 atm for an arbitrary feed composition. 

Graphical representations of these shaip splits are shown in Rgure 2.13. 

An interesting observation in azeotropic systems (that hence exhibit multiple distillation regions) is that while the feed composition may lie in one region, the 

FKJURE 2.14 An example of feasible designs at infinite reflux fcx- (a) the acetone/ methanol/chloroform system and (b) the acetone/benzene/chloroform system both operating at P = 1 atm. 

Example 2,2 Suppose an acetone/ethanol/methanol mixture of composition [0.3,0.3] is to be fed to a distillation column for separation. Determine 

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Consider the recovery of MIPK from an MEK-MlPK-water mixture. The approximate bow tie regions of product compositions for three different feeds are shown in Fig 13-81. From feed F3, which is situated in a different distillation region than the desired product, pure MIPK cannot be obtained at all. Feed F2 is more favorable, with the upper edge of the bow tie region along the MEK-MIPK (water-free) face of the composition triangle and part of the lower... 

We can then backmix whatever is taken off in either product with the other to reach any compositions that lie between the product compositions. Thus, we can reach any product in the shaded bow-tie region on this figure. 

FKiURK 2.15 RCM for the acetone/ethanol/medianol system, showing the unique disdlla tion regions and a bow tie region. 

Figure 5.2. Construction of bow-tie regions in RCM. Remark feasible residue curves must go through both shaded areas, so that top and bottom compositions line on a material balance line passing through the feed.

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