Carbon Dioxide Absorption in Water

percent recovery of

CO

2

92

Consider a mixture of 90 mole% nitrogen and 10 mole% carbon dioxide.

CO

2

is absorbed into water using an absorption column. The water intake at the top of the absorption column occurs at 5°C. The column operates at 10 atm. Operation is assumed isothermal due to the presence of cooling coils. The flow rate of the gas mixture entering at the bottom of the column is equal to 1 kmole/hr. This Demonstration lets you set the percent recovery of

CO

2

and displays the number of required equilibrium stages. For this problem, the solubility of

CO

2

in water is low. Indeed, the equilibrium relation is

y=87.6x

, where

y

and

x

are the mole fraction of

CO

2

in the gas and liquid. Thus, the gas phase concentration is considerably greater than its liquid counterpart. The liquid flow rate required for physical absorption would be too large, thus chemical absorption, analogous to that using ethanolamine, is a better method.