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[Title changed from _Vacuum Brewing of Beer_. The idea changes in the annotations, with ethanol production the new goal.]
Partly inspired by _The strongest beer ever_ (see link).
As has been noted elsewhere, the yeast used for fermenting beer tends to die when the alcohol level gets too high.
Brewers have been trying to breed more tolerant yeasts, with some success.
This idea is simply to put the entire brew pot, yeast and all, in a partial vacuum so the alcohol vaporizes off while the temperature stays at a level the yeast like. The vacuum would be maintained with a pump, using roughly the same energy as that needed to vaporize the alcohol in a heat-type distiller.
The assumption here is that the yeast critters can endure a partial vacuum while immersed in a proper-temperature liquid. The CO2 they produce might erupt more violently, making them dead, or might be more easily produced, making them happier. (The vacuumed-off CO2 could be separated from the alcohol easily, if desired.)
Vacuum fermentation of beer could be used in two ways. One is as a method of continuous-batch whiskey distilling, with the beer pot as the perpetual mash of the whiskey, and fresh ingredients added through a pressure lock. The beer-making method is to accumulate the alcohol and CO2, then dump them back into the brew pot, killing the yeast, and process as any other beer, producing what is technically not a fortified beer.
The strongest beer ever
The_20strongest_20beer_20ever
Breeding the yeast. [baconbrain, Mar 26 2008]
Elimination of alcohol by vacuum distillation
http://ejeafche.uvi...ask=doc_view&gid=28
[ldischler, Mar 28 2008]
Very similar patent
http://www.freepate...ne.com/4009075.html
[daseva, Mar 28 2008]
Google Patent Search
http://www.google.com/ptshp?tab=pt
Gives patent images and better information. [baconbrain, Mar 28 2008]
The effect of low pressure on cell respiration
http://www.jgp.org/...reprint/14/1/55.pdf
[ldischler, Mar 28 2008]
Vapor pressure and distillation
https://eee.uci.edu...em/RDGbpdistill.pdf
you will still get some water in the distillate but not much [afinehowdoyoudo, Mar 29 2008]
Vapor pressure of ethanol
http://www.s-ohe.com/Ethanol_cal.html
for those with numerical proclivities [afinehowdoyoudo, Mar 29 2008]
& Water
http://www.s-ohe.com/Water_cal.html
[afinehowdoyoudo, Mar 29 2008]
[link]
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I can't see any reason why this wouldn't work, which is a good start. |
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There is a problem here in that the alcohol and water form a solution that does not readily seperate, as such it is really quite difficult to vacuum distill the alcohol of(it is possible but a lot harder than is seems) |
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The trick would be to raise the vapor pressure of the alcohol by a mixture of warming and vacuum. |
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The yeast can probably manage quite well up to 35C - just less than blood heat - maybe even warmer, without the proteins de-nauturing and killing the yeast cells. |
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At the top of Everest, water "boils" at about 70C. |
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A phase diagram for a water/ethanol/sugar mixture should yield interesting results; in fact, this could be the basis fo a continuous-process reactor, where sugar and yeast nutruents are constantly added, the alcohol and CO2 flashed off, and dead yeast strained out. |
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So a heat distiller is getting both water and alcohol vapors and condensing them separately? This could do the same, then, and feed only the water back in, maybe? |
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Dead yeast? I'll drink to them. Yeah, a continuous process--that's what I should have Googled for. |
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<Googles> Ow! Continuous brewing was invented by Morton W. Coutts fairly recently. "High gravity" beer has lots of alcohol and is desired. Vacuum brewing was not found, and might still (heh-heh) work. New processes are possible, I'd say. |
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I'm out of my field of knowledge, though. I'm going to go Google some more. |
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I found some vacuum stills for home-made alcohol. They don't vacuum the yeast as it's fermenting, but the technology is there. |
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Yeah, it has been interesting. My further research finds that the low-pressure fermentation concept is out there, but obscure. Which may mean it doesn't work. |
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Nobody seems to have tried it for ethanol production, which is where the money is these days. I'm looking further into it, and dusting off an old distillation idea based on pulling a vacuum. |
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I thought about deleting this, and hiding in my basement to cackle over my plans. But I thought of this in the Halfbakery, and posted it in the Halfbakery. I'll leave it up, and update if I get any more info. |
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I'm guessing they wouldn't be able to live in a vacuum, but with a continuous injection of CO2, perhaps. |
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It's a partial vacuum. Which is why I should change the title to low-pressure. |
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I think yeasticles give off CO2, not consume it. |
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Thanks for the links. The wine PDF gives some good hints, though the process is applied to finished wines. "Vacuum stripping", there's a new term. My head hurts. 4009075 is similar, but not quite, and may be as close as this could get to working. |
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I looked it up in Google Patents, which I like (see link). A Google search on a topic often finds Free Patents, which give a patent number to put in Google Patents. Which gives more info. |
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Oh right, re: CO2 production. Also, wouldn't the cells rupture under low pressure? |
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No, only if there is an abrupt change of pressure. In a homeostatic environment, they won't be aware of what the pressure actually is, until it starts to impinge on the osmotic gradient across the cell membrane. |
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There's also the possibility of utilizing gradients in temperature and pressure. Make the tank deep enough, and the alcohol would just boil at the top--which doesn't do anything for the yeasts at the bottom, of course. I'm going to have to think about that . . . probably tonight while I'm trying to sleep. |
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There's a chance that the cells would pop if the alcohol boils internally. Also something to learn about. Thanks, [8th]. Where can I learn more about that? I happen to be reading about cell evolution, but not about cell function. I should just make a little unit see what happens--a cell test cell. |
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(Good God! This idea is showing up in Google searches already.) |
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Yeast requires some oxygen - agitating your beer at the beginning is encouraged, and that's the only point in the process that it is. |
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So it's possible that a vacuum may draw off some of the gas that the yeast like, making them less efficient. |
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And a high enough sugar environment to allow the yeast to continue to party (eat sugar, pee alcohol, have sex, and fart CO2 - what a life cycle) may have it's own side effects as well. |
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Yeah, this is pretty far out of my mechanical specialties. I just read about azeotrope mixtures (which may be what [jhomrighaus] referred to), and then bailed out of twenty pages on yeasts. I'm learning. Thanks. |
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//eat sugar, pee alcohol, have sex, and fart // |
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[globaltourniquet], yeast //have sex// with themselves.. |
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"The anaerobic respiration (carbon dioxide production) of yeast is not at all affected by low pressures." |
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That looks good. Thanks much, [ldischler]. |
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[iron_horse], thanks, too. |
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I'm thinking I'll use a refrigerator coil in the condenser, and pump the heat back into the fermentation tank to maintain temperature. I may be able to freeze the water out of the condensate to aid separation. (I'll perhaps cool and capture the CO2.) |
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In theory you could possibly use this method to create a low alcohol beer or that mysterious beer concentrate... |
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// cool and capture the CO2 // |
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Best to do it as liquid, so you'll need a compressor to get it up above its critical pressure. CO2 is usually shipped as a liquid in equilibrium with its saturated vapor, at ambient temperature (on Earth). |
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[rcarty], apologies to those procreative yeast whose reputation I've impugned |
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The CO2 will be somewhat cooled as part of condensing the ethanol and water out. Then the CO2 will be compressed with a pump, and the heat of compression run back into the fermentation pot. |
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According to Wikipedia, the best temperature for the best ethanol yeast is 30 degrees C. |
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According to the vapor pressure calculator (thanks, [iron_horse]) at 30 degrees C, ethanol has vapor pressure of 78.47 mmHg, while water is at 31.82 mmHg. After punching in other temperatures, I think that the percentage difference between the two increases with lower temperature. Which works in favor of this idea, I think. |
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Distillation using a vacuum allows use of lower temperatures and attain. At about 6 percent of atmospheric pressure the temperature of the still need only be 35° C at the upper range for conventional yeast but workable. However this low pressure makes it hard to condense the vapor, since there is a smaller temperature difference between the vapor and the condenser (whether air or water). But this pressure would work if you could get your fermentation to maintain the 35° C.
A pressure below 1/10 atmosphere must be maintained or azeotropic binding destroys all efficiency. Additionally the difference in volatility between the water and the alcohol is still very small, requiring a high reflux (condenser return) ratio. The amount of energy consumed is around 15000 BTU per pound etoh produced. |
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Alternately if the beer is at
0° F a 3% atmosphere would be enough that the etoh would skip the azetrophic binding and boil straight away reducing the energy cost to about 6000 BTU per lb. The height of the still however, would have to be very large to accommodate the large volume of very rarified vapor. Vacuum distillation appears uncompetitive with conventional distillation for any bulk purpose IMHO. |
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The other problem may be your vacuum pumps - watch out for the lubricant. You're going to be pumping a gas stream laden with water and alcohol. Many of the oils used in rotary vacuum pumps aren't exactly approved for food contact, being based on phosphates, silicone, or halogenated hydrocarbons. |
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Is there an FDA-approved vacuum pump oil on the market ? |
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There's a lot to learn here. Thanks, [WcW]. |
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As for pumps, I think I'll give up on them for condensation purposes. |
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For the ethanol and water, I plan to just have a refrigerated area and do surface condensation. The area may need to be larger than I thought, as the vapor will not be very dense, as [WcW] makes clear. The heat extracted will go back to the ferment tank. |
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The condensates will collect in standpipes, which will make a liquid column tall enough to reach normal room pressure at the bottom, so a simple valve will allow collection. No pump needed. |
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Condensing will be done with the aim of getting ethanol and water separately, but both liquids will condense to some extent in both places, making a range of mixtures. The liquids will be separated further down the line using standard procedures. |
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As for distillation efficiency--improvements over other methods are not the goal for this idea. A roughly comparable efficiency is acceptable. Pumping heat from the condensers back into the ferment tanks may be helpful. |
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The crux of this idea is that the yeast ferment need never be stopped, and can run as a continuous process. I'll see if I can detail how many steps that will save over normal procedures. It may not be worth the losses in other areas. |
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Ok so we have some issues: We have a lot of gas to remove all the time (CO2). We have to maintain a very high (ok, for process purposes) vacuum. The yeast will need some 02 to reproduce which it will have a very hard time getting unless we have a lot of oxidized compounds around. While evacuation of CO2 and Alcohol will speed fermentation it will also make the environment more desirable for aggressive spoilers.
The setup that would work, a piston action pump feeding into a condenser with parasitic fractional return (the water and replacement sugar are sucked back into the chamber by a feed valve) is so inefficient that, even though it requires no heat input, it consumes twice as much energy as is in the alcohol itself (pump and cooler working at impossible efficiency). At the end of the day its a neat but impractical idea. Further it is already baked in bio-pharma applications where reverse osmosis is impractical. |
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Ok so we have some issues: We have a lot of gas to remove all the time (CO2). We have to maintain a very high (ok, for process purposes) vacuum. The yeast will need some 02 to reproduce which it will have a very hard time getting unless we have a lot of oxidized compounds around. While evacuation of CO2 and Alcohol will speed fermentation it will also make the environment more desirable for aggressive spoilers.
The setup that would work, a piston action pump feeding into a condenser with parasitic fractional return (the water and replacement sugar are sucked back into the chamber by a feed valve) is so inefficient that, even though it requires no heat input, it consumes twice as much energy as is in the alcohol itself (pump and cooler working at impossible efficiency). At the end of the day its a neat but impractical idea. Further it is already baked in bio-pharma applications where reverse osmosis is impractical. Condensers are cold, not hot. Condensation warms surfaces, evaporation cools them (thermodynamics). All the heat we would want comes from the yeast (fermentation temperature distillation, remeber). There is no way to make this function without pumping. Further we will need some active cooling on the condenser side otherwise the process will rapidly grind to a halt. |
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Fermentation of sugar to alcohol is an
anaerobic process, shirley? |
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Yes, it is, but the thermodynamics are still vicious, as [wcw] points out. You need to keep vaccing out the Co2, even if you condense the ethanol and water (fractionally, so you need 2 regions with active cooling and close temeprature control) |
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//a neat but impractical idea // |
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<points meaningfully at sign saying "halfbakery"> |
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//a neat but impractical idea // |
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This has been educational for me. Thanks, all. |
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What's so impractical about it ?... doesn't strike me as being fast, but basically you just need a glucose drip on one side and a condenser on the other. Put it on a windowsill (in summer) for evaporation and keep the condenser tube in the shade. Every once-in-awhile come by and pump out the CO2, renewing the vacuum. |
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Might one of those little misters help (sound vaporiser) |
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Vacuum fermentation already exists. It is a form of extractive fermentation. As far as the azeotrope goes, reducing the pressure will change the compostion (I don't remember if it enchinches or depletes). As for condensing, the suction side of a vacuum pump is under vacuum, yes; but the outlet is under pressure, so the vapor should (depending on the vacuum/temperature) condense as it passes through the pump. |
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Tactical Nuclear Penguin. |
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