Dear All,

I need to estimate the vapor composition of the vapors coming from the methanol tank.

Operating data are as below:

Op Pressure: 10 mmAq(almost Atmospheric Tank)=101.423kPa

Op Temp(max.): 40 degC

Tank is provided with N2 blanketing to keep the positive pressure in the tank. Vapor coming from the tank shall be fed to the Vent Gas Canister and then finally to the ATM.

In the vapor space it will be Nitrogen and Methanol Vapor. I would like to know the method to determine the composition of the vapor going to the Vent Canister. The Canister replacement frequency will depend on this composition.

My approach is as below:

Considering the Dalton law, I made this equation:

X*MeOH Vapor Pressure @ 40 deg C+ (1-X)*N2 inlet pressure to tank= 101.423

Where X= mole fraction of methanol in the vapor

Vapor Pressure of Methanol @ 40 degC=32.011 kPa

The problem is we have two variable (N2 Press. and Mole fraction) but have only one equation. So there are many possibilities.

Kindly let me know if my approach is correct or not. What will be 2nd equation to determine the both variables(mole fraction, N2 Pressure) correctly. Also if there is any other method to determine the composition then let me know as well.

Regards

JKM

**Edited by JKM, 26 January 2018 - 12:33 AM.**