A gas stream comprising of air and  vapour of an organic compound is to be scrubbed in an absorption tower for  separation of organic compound by absorption in oil. The operation is  countercurrent. 

Given: Mol. wt. of oil: 250 kg/kmol; Inlet  concentration of vapour of organic compound in gas stream: 5% (by volume);  Targeted (or desired) removal of organic vapour: 95%; Flow rate of gas stream:  1000 m3/h at 1.2 bar and 30ºC; Mol wt of organic vapour: 80 kg/kmol and vapour  pressure of organic vapour at 30ºC is 0.125 bar. You can assume that the system  obeys Raoult’s law. If the inlet oil to the absorption column does not contain  any trace of organic vapour initially: 

Calculate  the minimum flow rate of oil to the column for desired removal of organic vapour.  

Calculate  the number of theoretical stages using Kremser’s equation if the absorption  factor A = L/mG = 1.4. 

If the inlet oil to the  absorption column contains 0.5% by mass of organic compound initially, answer  the following: 

•  Calculate the number of theoretical stages of the absorption factor L/mG = 1.4.