Page 82 - Separation process engineering

2.6 Multicomponent Flash Distillation

Equations (2-27) and (2-28) are solved along with the stoichiometric equations (2-31), the overall mass
balance Eq. (2-5), the component mass balances,

(2-36)

and the energy balance, Eq. (2-7). Equation (2-36) is very similar to the binary mass balance, Eq. (2-6).
Usually the feed flow rate, F, and the feed mole fractions z for C – 1 of the components will be specified.
i
If p drum and T drum or one liquid or vapor composition are also specified, then a sequential procedure can

be used. That is, the mass balances, stoichiometric equations, and equilibrium equations are solved
simultaneously, and then the energy balances are solved.

Now consider for a minute what this means. Suppose we have 10 components (C = 10). Then we must
find 10 K’s, 10 x’s, one L, and one V, or 32 variables. To do this we must solve 32 equations [10 Eq. (2-
27), 10 Eq. (2-31), and 10 independent mass balances, Eq. (2-36)] simultaneously. And this is the simpler