Two pressure systems

The two-pressure system is also used for the separation of acetonitrile-water, tetrahydrofuran-water, methanol-MEK, and methanol-acetone tFrank. 19971. In the latter application the second column is at 200 torr. Realize that these applications are rare. For most azeotropic systems the shift in the azeotrope with pressure is small, and use of the system shown in Figure 8-6 will involve a very large recycle stream This causes the first column to be rather large, and costs become excessive. 

C4. Sketch the McCabe-Thiele diagram for a two-pressure system similar to that of Figure 8-6. 

D14. We plan to use a two-pressure system (similar to Figure 8-6 to separate a feed that is 15.0 mol% benzene and 85.0 mol% ethanol. The feed rate is 100.0 kmol/h, and is a saturated liquid. The two columns will be at 101.3 kPa and 1333 kPa. We desire an ethanol product that is 99.2 mol% ethanol and a benzene product that is 99.4 mol% benzene. Assume the two distillate products are at the azeotrope concentrations. 

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