Details

The equilibrium line is calculated using Henry's law:

,

,

where is Henry's constant (atm), is pressure (atm), is Henry's constant at (atm), is the ideal gas constant (J/mol K), and is temperature (K).

The operating line is calculated from a mass balance around the stripper:

,

which rearranges to:

.

The operating line is:

,

where is the liquid solvent molar flow rate (Mmol/h), is the vapor molar flow rate (Mmol/h), is the mole ratio of the impurity in the inlet liquid solvent stream (ppm), is the mole ratio of the impurity in the inlet vapor stream (ppm), is the mole ratio of the impurity in the outlet liquid solvent stream (ppm) and is the mole ratio of the impurity in the outlet vapor stream (ppm).

To count off stages, start at on the operating line (, ) and draw a horizontal line to the equilibrium line , ). Then draw a vertical line down to the operating line. Repeat these steps until is reached.

The outlet liquid mole ratio is calculated from the mass balance:

.

Reference

[1] P. C. Wankat, Separation Process Engineering: Includes Mass Transfer Analysis, 3rd ed., Upper Saddle River, NJ: Prentice Hall, 2012.