Calculate the number of ideal stages for the system described in Example 20.1 if the conditions are changed to the following: 

Acetone in entering gas, 25 mole percent 

Acetone in entering oil, 1.5 mole percent 

Acetone in bottoms liquor, 8 mole percent 

Acetone absorbed, 90 percent

Example 20.1

By means of a plate column, acetone is absorbed from its mixture with air in a nonvolatile absorption oil. The entering gas contains 30 mole percent acetone, and the entering oil is acetone-free. Of the acetone in the air 97 percent is to be absorbed, and the concentrated liquor at the bottom of the tower is to contain 10 mole percent acetone. The equilibrium relationship is y_e = 1.9x_e. Plot the operating line and determine the number of ideal stages.