Exercise

1. An aqueous stream F of 0.11 kg/s comprises pyridine and water in

equal weights. This stream should be purified in a countercurrent

extraction process (see Figure 1). The concentration of pyridine in

the raffinate RN should be reduced to 5 wt% (or less). Pure benzene

is to be used as solvent S. The ternary equilibrium diagram of

water-pyridine-benzene is given in Figure 2.

a) Calculate the minimum solvent stream, Smin

b) The solvent stream Sis chosen to be 0.11 kg/s. Determine the value of flow

E₁

c)

d)

Determine the number of equilibrium separation stages, N.

Determine the size and composition of the extract leaving the second

stage, E₂,

17 ke/s. (c) Nr. = 3, (d) X