Question

When molasses is fermented to produce a liquor containing ethanol, a CO2-rich vapor

containing a small amount of ethanol is evolved. The alcohol will be recovered by

countercurrent absorption with water in a packed-bed tower. The gas will enter the tower at a

rate of 180 kmol/h, at 303 K and 110 kPa. The molar composition of the gas is 98% CO2 and

2% ethanol. The required recovery of the alcohol is 97%. Pure liquid water at 303 K will enter

the tower at the rate of 151.5 kmol/h. Estimate the packed height required to recover 97% of

the alcohol. The system ethanol-CO2-water at the given temperature and pressure obeys

Henry’s law with m=0.57. The diameter of the tower is 0.738 m and ky’a=0.191 kmol/m3 and

3 kx’a=0.402 kmol/m .

Answer 1