A column is required to recover acetone from an aqueous solution. The feed contains 5 mol per cent acetone. A product purity of 99.5 per cent w/w is required and the effluent water must contain less than 100 ppm acetone.

The feed temperature will range from 10 to 25 °C. The column will operate at atmospheric pressure. For a feed of 7500 kg/h, compare the designs for a sieve plate and packed column, for this duty. Use a reflux ratio of 3. Compare the capital and utility cost for the two designs.

No reboiler is required for this column; live steam can be used. Equilibrium data for the system acetone–water is given in Example 11.2.

Data from example 11.2

Acetone is to be recovered from an aqueous waste stream by continuous distillation. The feed contains 10 mol% acetone.  Acetone of at least 95 mol% purity is wanted, and the aqueous effluent must not contain more than 1 mol% acetone. The feed will be a saturated liquid. Estimate the number of ideal stages required.