Ethanol-Water Vaccum Distillation

[zamu2010]

Hi folks,
I have a Ethanol-Water solution containing 3 vol% of Ethanol.
I am looking into the possibilities to do the vaccum distillation in order to concentrate it to 90 vol% Ethanol.
Can someone suggest how to see the effect of vaccum on the boiling point of the solution? and how the distillation unit can be sized for that....
Thanks in advance for your comments on this.
Br
ZAMU

 

[StoneCold]

ZAMU
Vacuum is your enemy in distillation. Unless you have a waste heat stream that you are going to use on the reboiler you should go with atmospheric distillation.

Regards
StoneCold

 

[zamu2010]

Thanks for your reply Stone Cold.
The CAPEX and OPEX are not justifed against the amount of ethanol recovered for atmospheric distillation. Vaccum distillation or flashing under vaccum might be a better solution. Though I have a feeling with vaccum distillation the CAPEX would be higher due to bigger diameter column required and Opex will be lower as compared to atmospheric distillation.

 

[StoneCold]

ZAMU
Your recovery will probably be lower under vacuum than at atmospheric, due to losses to the vacuum unit, and the separation is harder because the boiling points converge under vacuum. The CAPEX and OPEX will be higher for vacuum distillation unless you have a waste heat stream to use. So if this project is a loser at atmospheric, changing the pressure will not help you out. Maybe pervaporation would help you, I don't know the relative costs on that.

Regards
StoneCold

 

[25362]

It seems that adding water soluble ionic compounds can increase ethanol's relative volatility. Would you care to try it?