[dspisak]

Hi, folks. This is my first post here.  I did a search in the forums but did not find an applicable topic.

We plan bubble N2 through various alcohols then add the saturated N2 to an air stream.  The N2 stream may be 3 CFM and the air stream may be as high as 100 CFM.  Here is my question...

Assume the air stream contains 0.015 lb-water/lb-air and the N2 stream contains 0.015 lb-methanol/lb-N2.  In the air/N2 mixture the alcohol content would be about 0.0005 lb-methanol/lb-air.  I think the total vapor content would be 0.015+0.0005=0.0155 lb water+alcohol/lb-air.

Are the amounts of vapors in an air system additive, i.e. does the "humidity" of the air increase or are the completely independent?  Another way of looking at the problem is if the air is at 100% humidity with water can the air absorb the additional alcohol vapor?

Any guidance will be appreciated.  TIA

Dan

[Stepan]

Sounds correct if you take in account all dilutions. Please note that it is hard to gen exact concentration by saturation. Saturation is not perfect, temperature of the vessel drops, micro droplets of alcohol will add significantly to vapour concentration.

Also you may want to consider a different setup where you inject liquid methanol into gas stream. You need only 1-2 mL/min. It would be much easier to operate, maintain and change the flow rate.