6.8. Absorption of acetone from air. Ninety-five percent of the acetone vapor in an 85 vol air stream is to be absorbed by countercurrent contact with pure water in a valve-tray column with an expected overall tray efficiency of 50%. The column will operate at 20°C and 101 kPa. Equilibrium data for acetone-water at these conditions are as follows: Acetone in water, mol 3.30 7.20 11.7 17.1 Acetone partial pressure in air, torr 30.00 62.80 85.4 103.0 Calculate (a) the minimum value of L'/V", the ratio mol H₂O/mol air: (b) the total number of equilibrium stages using a value of L'/V' of 1.25 times the minimum; and (c) the concentration of acetone in the exit water. From Table 5.3 for N connected equilibrium stages, there are 2N+ 2C+5 degrees of freedom. The following values are specified in this problem: Stage pressures (101 kPa) Stage temperatures (20°C) Feed stream composition Water stream composition Feed stream, T. P Water stream, T. P Acetone recovery L/V |xx J Juma 1 2N+2C+4 One more specification is needed. Take the gas feed rate at 100 kmol/h.

Fig: 1