6.8. Absorption of acetone from air. Ninety-five percent of the acetone vapor in an 85 vol%...

 

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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 20C and 101 kPa. Equilibrium data for acetone-water at these conditions are: Mole-percent acetone in water 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 HO/mol air; (b) Nt, using a value of L'/V' of 1.25 times the minimum; and (c) the concentration of acetone in the exit water. From Table 5.2 for N connected equilibrium stages, there are 2N+2C+5 degrees of freedom. Specified in this problem are: Stage pressures (101 kPa) Stage temperatures (20C) Feed stream composition Water stream composition Feed stream T, P Water stream, T, P Acetone recovery L/V N N C-1 C-1 22 2 1 1 2N+2C+4 The last specification is the gas feed rate at 100 kmol/h. 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 20C and 101 kPa. Equilibrium data for acetone-water at these conditions are: Mole-percent acetone in water 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 HO/mol air; (b) Nt, using a value of L'/V' of 1.25 times the minimum; and (c) the concentration of acetone in the exit water. From Table 5.2 for N connected equilibrium stages, there are 2N+2C+5 degrees of freedom. Specified in this problem are: Stage pressures (101 kPa) Stage temperatures (20C) Feed stream composition Water stream composition Feed stream T, P Water stream, T, P Acetone recovery L/V N N C-1 C-1 22 2 1 1 2N+2C+4 The last specification is the gas feed rate at 100 kmol/h.