1 reply to this topic

[gingerbrew]

We need to remove alcohol from a beer that has 1.5% alcohol and we would like it to be closer to 0.5% or even less. we would like to preserve flavor so we are thinking vacuum. We have two ways we are considering doing this. One is a very simple batch method where we put a 1800 gallon tank with the 1.5% alcohol beer under vacuum and apply some heat so that we drive off the alcohol at a temperature above ambient but not too high to upset the taste. i do not know how to calculate the time needed to extract the alcohol. I would pay someone to do this for us if it is very complex. Or we could create a column and distill of the alcohol. That we have created a test column for and we run it at 28.5 in Hg vacuum and 85 degF. Now we have to scale this up and well that would be expensive. we already have the tanks that we could apply vacuum to. just have to buy a vacuum pump in theory. thanks for your help.

[kkala]

I am not familiar with brewery, though alcohol free bear (max 0.5% alcohol v/v) has been tasted. Following thoughts are presented, for want of more precise data from someone else. Comments on them would be welcomed for a better and more complete picture.
1. Googling "alcohol free bear preparation" (or similar) can reveal interesting info, if not already available; e.g. http://www.tandfonline.com/doi/abs/10.1080/87559129.2010.496022, or http://en.wikipedia.org/wiki/Low-alcohol_beer, etc. Probably critical web investigation by one knowing brewery process could indicate pros and cons of each method / option.
2. The tank -vacuum pump option is a part of a vacuum evaporator system. This could be composed of a vertical evaporator (e.g. from tank modifications), disengagement space above it, then vapor cooling followed by vacuum pump. Due to low alcohol content in the liquid, vapors are judged to be composed mostly of water gas, and boiling point close to that of water at the chosen operating pressure (see Perry 7th edition, Fig 2-10, Enthalpy - concentration diagram for aqueous CH3CH2OH).
Vacuum pump will take out not condensed vapors (most of them will be condensed by cooling) and non condensable gases. The latter include leakages of ambient air into the equipment, which is not easy to predict theoretically. So required vacuum pump capacity is hard to specify.
3. The distillation column will result in condensed vapors out richer in alcohol, but this option is expected to be of higher capital cost. If it concerns a packed tower, scale up criteria could be found in "Pilot plants, models and scale-up methods in chemical engineering" by R E Johnstone and M W Thring (McGraw-Hill, 1957), Chapter 13 (Packed Towers).

Edited by kkala, 03 June 2012 - 10:12 AM.