Example 8.4: Flash Separator
When the pressure of a compressed liquid is brought between the bubble point and the dew point, the liquid "flashes," that is, it partially evaporates, creating a vapor that is enriched in the more volatile components and a
liquid that is enriched in the heavier components. This simple process provides partial separation of the components.
A mixture of heptane/decane at 1.8 bar, 120 °C contains 80% by mol heptane. At what pressure should it be flashed to obtain a stream that is 90% rich in heptane? What are the composition of the liquid and the amounts of the two phases?