Chapter 12, Problem 9P

Chemical/Bio Engineering

A stage extraction process is depicted in Fig. P12.9. In such systems, a stream containing a weight fraction $Y_{in}$ of a chemical enters from the left at a mass flow rate of $F_1$. Simultaneously, a solvent carrying a weight fraction $X_{in}$ of the same chemical enters from the right at a flow rate of $F_2$. Thus, for stage i, a mass balance can be represented as

$F_1{Y}_{i-1}+F_2{X}_{i+1}=F_1{Y}_i+F_2{X}_i$ ( P12.9.1)

At each stage, an equilibrium is assumed to be established between $Y_1$ and $X_1$ as in

$K=\frac{X_i}{Y_i}$ ( P12.9.2)

FIGURE P12.9

A stage extraction process.