Page 219 - Separation process engineering

The external balance equations for the column shown in Figure 5-1 are easily developed. These are the
overall balance equation,
Table 5-1. Specified design variables for ternary distillation

(5-1)

the component balance equations,

(5-2)

and the overall energy balance,

(5-3)

Since we are using mole fractions, the mole fractions must sum to 1.

(5-4a)

(5-4b)

For a ternary system, Eqs. (5-2) can be written three times, but these equations must add to give Eq. (5-1).
Thus, only two of Eqs. (5-2) plus Eq. (5-1) are independent.
For a single feed column, we can solve any one of Eqs. (5-2) simultaneously with Eq. (5-1) to obtain
results analogous to the binary Eqs. (3-3) and (3-4).

(5-5)