RobbieOByrne
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Is it possible and how?
Collecting CO2 from fermentation
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It's fairly easy to collect it at atmospheric pressure, and with a little more effort you could collect it at about 2X atmospheric pressure. More than that your going to need so fancy equipment. So do you want details on low pressure collection? And how pure do you want it to be?
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RobbieOByrne
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Yes please. If I'm using it for kegs does purity matter and how would you make it pure? I heard a rumor of local brewery providing CO2...
https://www.homebrewtalk.com/forum/threads/co2-scincey-type-stuff-questions
Long story short, carbonate in the keg naturally if you want, push the beer with purchased gas.
Long story short, carbonate in the keg naturally if you want, push the beer with purchased gas.
There’s information to ferment under pressure in corny kegs. Consider using a fermenting corny keg with a spunding valve slightly above serving pressure and then a T-connector to the finished beer thats been carbonated with sugar. Given you only have a few days during active fermentation to use the CO2, but if you planned your brew day to coincide with heavy keg use days then it could make a difference.
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RobbieOByrne
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I’m asking about how to collect CO2 from fermentation not keg carbonating thanks though.
bierhaus15
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It is is not feasible for home brewing. Commercial systems use a bevy of equipment that both cleans, dehydrates, and concentrates the C02 for re-usual. If serious, contact Pentair/Haffmans, but I do not know of any system that does this on a small scale.
You can easily collect it over water (fill a carboy with water to the very brim and invert it in a pan also filled with water, place a hose from the fermenter into the neck of the carboy). The gas in the carboy after the water is displaced will be saturated with water vapor and also contain volatiles from the fermentation. Those can be removed by passing the gas over water absorbing compounds and over GAC. This obviously will require pumps and pressure vessels to pump the gas into.
For natural carbonation just load the beer into the kegs a bit shy of terminal gravity. The last 1 - 2 °P will carbonate the beer - just the way you used to do with priming sugar when you got started in all of this. You will, of course, have yeast sediment in the kegs but if you don't move them who cares? In fact they will keep the beer in the reduced state which prevents diacetyl formation and staling. You can always rack some off against counter pressure if you want to take beer to a party for example.
For natural carbonation just load the beer into the kegs a bit shy of terminal gravity. The last 1 - 2 °P will carbonate the beer - just the way you used to do with priming sugar when you got started in all of this. You will, of course, have yeast sediment in the kegs but if you don't move them who cares? In fact they will keep the beer in the reduced state which prevents diacetyl formation and staling. You can always rack some off against counter pressure if you want to take beer to a party for example.
That's cool and all. But you will have what, slightly more than a mol of mixed gas? Gonna take a whole lot more than that once the co2 is condensed to have any applicable use whatsoever.
The issue you have is your fermenter needs to be a pressure vessel, and you bleed off container needs to be a pressure vessel. Cool, now you have a whole lot more mixed gas, stored at a high pressure, great. Only problem, you are now fermenting at very high pressure. Similar to the concerns of osmotic pressure due to high sugar content wort.
His intended use is to carbonate his beer. Who cares about the moles? What matters is the volume. If he ferments at atmospheric and collects two carboy's full he will have 1 volume in the beer remaining in the fermenter and two to add back to get 3 volumes.
Not really. You do need to seal it but the maximum pressure level will be 20 some inWC.
Again, no but you will need a pump to get the gas in the collection vessels up to high enough pressure to force the gas through the GAC filter (no need to remove the water for this application).
No, not at all unless you consider 20 IWC high pressure.
Brewers do have to watch pressure effects on yeast but this is a concern where fermenters are 60 feet high (a couple of bars hydrostatic pressure), not where a cylindroconical is spunded to a bar or so.
I am not saying that what OP proposes to do is in any sense practical for the home brewer. If a home brewer wants natural carbonation his best bet is to let the beer ferment down to a few degrees from terminal, let the last few degrees extract take it to the pressure level required for the dissolved volume and/or use priming sugar or wort to carbonate the beer after it has been allowed to reach to close to terminal.
We are making a similar argument, the part you seem to be not understanding is how to achieve a useful product.
So I understand, you say max pressure is 20 inches, 0.72psi? I sure hope that's Gage, and not absolute....
Jesus Christ no, you pump your "CO2" out of your inverted fermentor. Now you've pulled a strong vacuum within the fermenter. How does this not require a pressure vessel???
60' of hydrostatic is otherwise known as 26psi. You're gonna lose all that pressure just about the moment you open the canister, unless of course your pulling from a volume around the size of a retired coal mine.
The op asked how to harvest co2, if he wants to do that, it's gonna have to be fermented st a higher pressure at the homebrew scale.
This, I certainly agree with.
Actually I don't recall seeing what the OP wants to do with the collected co2 specifically. "For kegs." Can mean a few things. The question was if collection was possible. Answer is yes and how is a lot of ways including displacing a container full of water or filling an expandable bladder.
What to do with this co2 at low pressure? Not much. Purging other vessels perhaps? Hack an air compressor to compress it?
Long story short.... You have to buy a co2 tank for most practical uses and get it filled regularly.
What to do with this co2 at low pressure? Not much. Purging other vessels perhaps? Hack an air compressor to compress it?
Long story short.... You have to buy a co2 tank for most practical uses and get it filled regularly.
I stated quite plainly how you could make a useful product. It's not clear what "useful" means to OP. He first asks how one would purify the gas for keging and then in a later post says that's not what he want's it for.
If you have an inverted carboy with 20" of water in it and someone says the pressure in a tube in its mouth is 20 IWC, how could you think absolute was meant?
Amida Butsu yes. The fermenter is never inverted. The gas is collected over water in an inverted container of some sort. The gas is then pumped out of this container, through the filters and into a pressure vessel. As the gas is pumped out the pressure inside the headspace of the inverted bottle is lowered and the water rises to take it's place. The vacuum in the bottle never goes much lower than 20" WC unless you have a humungous pump (a carpenters air compressor with an additional oil filter in the line would do). I'll leave figuring out whether that's gauge or absolute as an exercise for the reader.
I know this was typed in the later hours of the day and perhaps the beverage we are focused on here may have been involved but hydrostatic, while in general can refer to any fluid, in the context here clearly refers to 60' of beer in one of the huge cylindro conicals used by the mega breweries. At the bottoms of those the cerivisastatic pressure is, if the fermenter is full to a height of 60', a bit over 60 feet water column plus whatever the head pressure is. If you open a valve at the bottom to ambient the beer does come rushing out and it is a very sad thing (I've done it but with cylindro conicals a lot less impressive than 60') but it takes long enough that most of the beer can be saved if you reclose the valve as soon as you see your mistake. If you use an empty cylindroconical to collect your CO2 and have pumped it up to a couple bars and then accidentally open a valve to ambient you aren't "gonna" lose all your gas in an instant. But you will lose a lot of it which, given all the trouble you have gone to is also a tragedy.
It has been explained by a couple of people here that a couple IWC is the highest pressure needed for the collection phase. When I collect CO2 over water the pressure gauge on the fermenter doesn't even move off the peg.
After my post the OP said that it’s not for carbonating his beer. My guess even though he doesn’t explicitly say so is that he would like to collect the gas, fill CO2 tanks and sell them. It’s a good idea too, but the cost of the equipment needed would probably not balance with the relatively small amount of CO2 produced.
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RobbieOByrne
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So no one is confused the first question was for everyone, “collecting CO2 from fermentation, is it possible and how”. Then Doug asked if I wanted more details, to which I said yes to Doug specifically. I want to know the full process for every way possible. Usage of CO2 doesn’t matter... the collection of CO2 is the primary question. Secondary questions are address to individuals who bring up additional processes. IE how to purify CO2.
OK. Here's an idea I had on how to collect gas and carbonate/serve beer with no CO2 cylinder. I think it would work. Maybe. I never went ahead with this because it's less hassle to just buy gas. But since you asked...
Firstly you need to pressure ferment. In cornys or whatever. Your beer comes out carbonated saving you gas right there. But that's only part 1.
Part 2. While you ferment, you daisy-chain say 3 spare sanitised kegs to your fermentor.
Like this...
Fermentor gas -> keg1 liquid.
keg1 gas -> keg2 liquid.
keg2 gas -> keg3 liquid.
keg3 gas -> spunding valve.
Ferment at whatever pressure you like but make sure you tighten the spunding valve to finish at 20psi.
Now you have 3 empty kegs at 20psi. Crash cool your fermentor and you have a fermentor of cold carbonated beer at around 10-12psi.
On your kegorator you buy one of those secondary regulator things designed for connecting to your main reg that lets you set a specific keg to a different (lower) pressure. Rig up that secondary regulator input to go to a grey gas disconnect and the output goes into your kegorator for serving.
Now you connect one of the gassed up corny kegs to the regulator input via the gas disconnect. This feeds 20psi into the reg which outputs at 12psi. This will serve your beer normally until the input gets down to 12psi.
When this happens you need to swap over to the next 20psi input keg. Hopefully 3 kegs at 20psi is enough to serve 1 keg worth of beer at 12psi. I have no idea if it is, I'm sure there's some science that can confirm one way or another.
In theory, this gives you free serving CO2 with a bit of extra faffing around and a requirement for 3 extra kegs and a regulator. I don't know if it's an issue to use gas from one fermentation in another brew - maybe - but I'm always purging kegs with fermentation gas and haven't had any infections etc.
I'd be interested to hear what other people think about this idea. I'm not looking to implement, more of an academic thing.
Firstly you need to pressure ferment. In cornys or whatever. Your beer comes out carbonated saving you gas right there. But that's only part 1.
Part 2. While you ferment, you daisy-chain say 3 spare sanitised kegs to your fermentor.
Like this...
Fermentor gas -> keg1 liquid.
keg1 gas -> keg2 liquid.
keg2 gas -> keg3 liquid.
keg3 gas -> spunding valve.
Ferment at whatever pressure you like but make sure you tighten the spunding valve to finish at 20psi.
Now you have 3 empty kegs at 20psi. Crash cool your fermentor and you have a fermentor of cold carbonated beer at around 10-12psi.
On your kegorator you buy one of those secondary regulator things designed for connecting to your main reg that lets you set a specific keg to a different (lower) pressure. Rig up that secondary regulator input to go to a grey gas disconnect and the output goes into your kegorator for serving.
Now you connect one of the gassed up corny kegs to the regulator input via the gas disconnect. This feeds 20psi into the reg which outputs at 12psi. This will serve your beer normally until the input gets down to 12psi.
When this happens you need to swap over to the next 20psi input keg. Hopefully 3 kegs at 20psi is enough to serve 1 keg worth of beer at 12psi. I have no idea if it is, I'm sure there's some science that can confirm one way or another.
In theory, this gives you free serving CO2 with a bit of extra faffing around and a requirement for 3 extra kegs and a regulator. I don't know if it's an issue to use gas from one fermentation in another brew - maybe - but I'm always purging kegs with fermentation gas and haven't had any infections etc.
I'd be interested to hear what other people think about this idea. I'm not looking to implement, more of an academic thing.
Just a few issues with your idea, in decreasing order of relevance:
- your kegs are filled with air (21% O2) and will need to be purged. If you let the fermentation CO2 purge them you'll end up with very high residual O2, a lot more than what you would have in even the lowest grade CO2 you can purchase. After all, with this setup your headspace is over three times your beer volume, which is quite unusual.
- fermentation CO2 is itself contaminated with fermentation by-products. Lager ferms are particulary affected and can have, especially at the beginning, quite a foul smell. Without treatment you'll be trapping those smells and pushing them back into the serving keg and possibly your beer.
- your CO2 will be saturated with water vapor. The stainless keg won't mind but the regulator might suffer from it.
- you have to conduct all your fermentations under pressure. This will systematically change the character of all your beers, albeit not necessarily for the worst. It's just another variable that you'll introduce.
- without a compressor you'll waste almost two thirds of collected CO2 as you'll need to switch CO2 keg as soon as pressures equalize, but you'll probably still have enough CO2 to serve all your beer.
- you need 4 times the number of kegs you would otherwise need, this can become quite space-consuming if you have several kegs in maturation/on tap.
- you'll probably only save a fraction of a dollar per batch, which means it'll take you dozens of years to recover the cost of the additional hardware.
- your kegs are filled with air (21% O2) and will need to be purged. If you let the fermentation CO2 purge them you'll end up with very high residual O2, a lot more than what you would have in even the lowest grade CO2 you can purchase. After all, with this setup your headspace is over three times your beer volume, which is quite unusual.
- fermentation CO2 is itself contaminated with fermentation by-products. Lager ferms are particulary affected and can have, especially at the beginning, quite a foul smell. Without treatment you'll be trapping those smells and pushing them back into the serving keg and possibly your beer.
- your CO2 will be saturated with water vapor. The stainless keg won't mind but the regulator might suffer from it.
- you have to conduct all your fermentations under pressure. This will systematically change the character of all your beers, albeit not necessarily for the worst. It's just another variable that you'll introduce.
- without a compressor you'll waste almost two thirds of collected CO2 as you'll need to switch CO2 keg as soon as pressures equalize, but you'll probably still have enough CO2 to serve all your beer.
- you need 4 times the number of kegs you would otherwise need, this can become quite space-consuming if you have several kegs in maturation/on tap.
- you'll probably only save a fraction of a dollar per batch, which means it'll take you dozens of years to recover the cost of the additional hardware.
Have you actually calculated the residual O2? The answer might surprise you. I did just that for purging a single keg, and the residual O2 came out at 5 ppb (yes parts per billion.) It would obviously be higher for more than one keg. By starting with liquid filled kegs, and letting the ferm chamber headspace purge prior to connecting the kegs, the residual O2 could be brought down significantly.
I'm curious just what the volatile ferm byproducts are, and when they come off during fermentation. If most of them come off early in the fermentation, then this could probably be worked around, but if significant byproducts come off later in the fermentation, then they can't be passively flushed. Can anyone recommend any references on this topic.
Personally, I don't see any useful purpose for CO2 collection other than CO2 purging of kegs, and preventing O2 suck back during cold crashing.
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doug293cz
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Two options for collecting significant amounts of CO2 (@ajdelange & @Sadu) have been presented. My suggestion would have been very similar to Sadu's.
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RobbieOByrne
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Sorry if I came off as rude, not my intention at all.
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