CO2 gathering

so it occurred to me the other day that I am going to be buying CO2 (I just started kegging), and I was producing plenty of the stuff when I was fermenting my beer. Now I understand its impossible (read to damn expensive) for me to reproduce the amount of pressure I would get when I buy the co2 from the store (I believe its something like 830 psi until the liquid CO2 is depleted), but I thought It would be novel and I just don't like the thought of throwing away something only to buy the same exact thing.

The thought I had was this:

I collect the CO2 over water by piping the carboy into a C02 "reservoir" and then pumping it into an air compressor that I have had vacuum pumped (to remove nearly all the air). The C02 reservoir would have a float switch which kicked the compressor on and off. it would also have a port to the water reservoir, which would allow the water to escape the co2 reservoir when displaced. The water reservoir would have to be weighted on a see saw like thing so that as it filled with water it would fall as to keep the whole system zero pressure.


any obvious shortcomings?

I have absolutely no idea if what you are trying to do is plausible but I will tell you this..... I pay $15 for a years supply of CO2.

ajwillys said:

I have absolutely no idea if what you are trying to do is plausible but I will tell you this..... I pay $15 for a years supply of CO2.

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+1 DIY is fun, but eventually reality comes comes crashing down on the practical side.

If you want to do it just to say you did it, but if the sole reason is money saving on Co2 costs, See above.

The reservoir will have to be at least 15-20 psi to be useful for carbonating and serving. Collecting over water and relying on the water column to provide pressure, you're looking at a 40-50 foot tall tank.

david_42 said:

The reservoir will have to be at least 15-20 psi to be useful for carbonating and serving. Collecting over water and relying on the water column to provide pressure, you're looking at a 40-50 foot tall tank.

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err... not what I meant.

the water reservoir falls as the co2 reservoir fills making sure that the co2 enters the co2 reservoir at almost 0 psi because if the pressure where too high it would inhibit fermentation.

the air compressor would take co2 out of the co2 reservoir and store it in its tank, by doing so the water reservoir would rise and the co2 reservoir would fill back up with water.

I wonder if instead of using an air compressor if you could just use city water pressure to get you up to 60 PSI or so.

Also wouldn't there be other gasses besides Co2 mixed in from yeast production?

One idea I had once to save the carbonation was to replace the airlock in the fermenter with an adjustable pressure relief valve. You could set the valve at 12 psi and then the fermenting beer would already be carbonated when it was done. I'm sure there's something wrong with this plan though. You're idea is certainly interesting.

Shortcomings:

Lack of CO2 volume produced by the fermentation process, it would take years to produce the volume required to force carb even one cornie

The process of evacuating your entire system of air prior to the introduction of CO2 from the fermentation process would be very costly

A compressor would more than likely bleed in air to your process and would more than likely require oil to run thus contaminating your gas

Basically a very costly and inefficient method of producing something you can buy for dirt cheap

pressurized fermentation. You'll start with carbed beer and only have to push it.

sigmund said:

Shortcomings:

Lack of CO2 volume produced by the fermentation process, it would take years to produce the volume required to force carb even one cornie

...

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While I agree with the rest of your points, I disagree with this one. Enough CO2 is produced during the consumption of 5 oz of dextrose to carb 53 bottles, there certainly is enough CO2 produced during fermentation to carb the batch. ajwillys' comment is the low cost way to do it, just build a spunding valve and ferment under pressure.

Racking carbonated beer is going to be a messy task.

EdWort said:

Racking carbonated beer is going to be a messy task.

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you transfer from one pressurized vessel to another, pushing with CO2. There's a whole thread on here where a guy has a set up with sankes and does this.

Why couldn't you just make a jumper hose with some tubing and two black liquid quick disconnects? Then you could just hook the fermetation keg up to the serving keg, you'll get some foaming at first until the pressure equalizes, but then you can let off pressure slowly in the serving keg (pressure relief valve, or the spunding valve). You still may need to set the fermentation keg above the serving keg so that you let it siphon the last bit out (as pressure will have decreased dramatically in that keg)

(all of this to avoid pushing with Co2, because if you are doing that... how are you saving Co2 by using the fermentation process to carbonate your beer then pushing it out with Co2)

https://www.homebrewtalk.com/f13/closed-system-pressurized-fermentation-technique-44344/

Closed-system pressurized fermentation - Home Brewing Wiki

sigmund said:

Shortcomings:

1.)Lack of CO2 volume produced by the fermentation process, it would take years to produce the volume required to force carb even one cornie

2.)The process of evacuating your entire system of air prior to the introduction of CO2 from the fermentation process would be very costly

3)A compressor would more than likely bleed in air to your process and would more than likely require oil to run thus contaminating your gas

4)Basically a very costly and inefficient method of producing something you can buy for dirt cheap

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(I added numbers for ease of reference)

1.) its already been covered but remember to raise the psi to ~15 you need only double the volume of the head space. that's because the pressure bearing down on us all the time is about 14.7 psi.

2.) not necessarily. if you filled a corny with water, sealed it and displaced the co2 your keg would be devoid of air. then you pour in the wort via the diptube side of the corny and collect the co2 again.

3.) perhapes. I like the idea of using water pressure to drive the co2 pressure up though. Its cheap and "elegant." I might try it that way.

4.) I don't think It'd be expensive, but inefficient surely.

One problem you might not have considered is co2 absorption into the water in the storage container, might not have any free co2 after trying to capture the gas, it would absorb into the water instead.

Good point, you may want to use a bladder tank to hold your Co2 so that it is separate from the water, but still gets the pressure from there.

kladue said:

One problem you might not have considered is co2 absorption into the water in the storage container, might not have any free co2 after trying to capture the gas, it would absorb into the water instead.

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While I am sure you are right, if it is at room temp the water will have a hard time holding onto the pressure. As you release the co2 into the keg the pressure will drop. Then the co2 in the water will escape because it is no longer under as much pressure. I just don't think you would loose that much. Of course if you can figure out an easy bladder then there is no reason not to.

I really like the idea of using water pressure from the tap as the pressurizer. I might try this for a kick. Maybe daisy chain a few corny kegs together.

Anyone know the volume (at normal air pressure) of co2 you would need to capture. It has to be huge.

Although it is a crude (i am work so I can not spend all day playing it MSpaint) Here is a quick pic to explain my idea.



If i remember right co2 is heavier than most of the normal air around us. So as it fills it will make the O2 and other unwanted gasses rise. Those gasses will be forced into the next keg and then to the next. you will have to vent the last in the chain to get rid of the normal air. Not sure how you know when to stop venting.

Then replace the carboy with a water faucet. It should fill up at least 1 if not 3 with water. I would remove these kegs filled with water.

I am not sure 4 kegs is enough. They will only lightly pressurized before the addition of water pressure so there is not that much co2 in them.

I am not sure how you would then control the pressure. Without building a water tower to get the exact amount of pressure from the water, you will need to have an inline regulator (either on the water or the co2.) But that costs money.

In the end throwing some priming sugar in a keg seems much easier for carbonating. And if you want to go through the trouble of this you could use it to dispense.

I do not intend to do this.

Add priming sugar to your keg. Near-free carbonation and all you have to do is push it with added CO2.

madewithchicken said:

Although it is a crude (i am work so I can not spend all day playing it MSpaint) Here is a quick pic to explain my idea.

If i remember right co2 is heavier than most of the normal air around us. So as it fills it will make the O2 and other unwanted gasses rise. Those gasses will be forced into the next keg and then to the next. you will have to vent the last in the chain to get rid of the normal air. Not sure how you know when to stop venting.

Then replace the carboy with a water faucet. It should fill up at least 1 if not 3 with water. I would remove these kegs filled with water.

I am not sure 4 kegs is enough. They will only lightly pressurized before the addition of water pressure so there is not that much co2 in them.

I am not sure how you would then control the pressure. Without building a water tower to get the exact amount of pressure from the water, you will need to have an inline regulator (either on the water or the co2.) But that costs money.

In the end throwing some priming sugar in a keg seems much easier for carbonating. And if you want to go through the trouble of this you could use it to dispense.

I do not intend to do this.

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I like how you think with this! You won't have co2 absorbed into the water since it is in contact for so little time.

If I were to do this I'd connect them with clear tubing, use 4 kegs (at least to start) and turn the water on, then when you see water about to go into the last keg (meaning all your Co2 is now concentrated there) you could stop it and then hook that keg up to a regulator, you'd have something like 45 PSI I think in there.

Yeah i thought of that too, but I was trying to keep my post short.

I have to admit that I am tempted to do this. But I don't want to buy 8 extra keg connectors. I could use the ones I have already, but I am using them and that sounds like a lot of work.

Also the CO2 place is on my way home from work. So it is real easy for me to just stop and get CO2.

True, and I pay a fairly high price (I think) for my water, so this might actually cost money in the end. Either priming the kegs or just buying a 20# tank for co2 is probably a lot more economical.

madewithchicken said:

Anyone know the volume (at normal air pressure) of co2 you would need to capture. It has to be huge.

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in short twice the volume that you want to use.

because

Boyle's Law said:

For a fixed amount of an ideal gas kept at a fixed temperature, P [pressure] and V [volume] are inversely proportional

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&

http://www.tpub.com/content/engine/14105/css/14105_18.htm said:

atmospheric pressure at sea level is approximately 14.7 psi.

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which also means that to pressurize the co2 to 15lbs you would want to fill half of your storage container with water and then pour the same amount of water in as beer out.

If I reinforced two 5 gallon buckets, connect them and allow them fill them with water, then allowed the co2 to displace the water, then pump the water back into one of the buckets I'd have a pressure of about 15 psi. I could use this

944play said:

LDPE and PP Drum Liners - US Plastic Corporation

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for bladders.

does it mean I'm going to? not necessarily but it is nice mind candy

not to beat a dead horse but I had another idea



use three corny kegs, one high pressure, one gathering vessle, on for pressurising. open the valve for C02 in and let the gathering tube displace the water that it was filled to the brim with.

when it is full close the in valve and the valves on the pressurizing keg now filled with water, open up the valve between the gathering and the high pressure, connect either water pressure or air pressure to the pressurizing keg, and drive the water back into the gathering keg and compressing the co2

when the gathering keg is full of water close the valve between it and the high pressure keg open the valve to the one way valve and let what little ambiant pressure there exist find an equailbrum. open the in valve, rinse and repeat.

water pressure should be able to pressurize the high pressure keg to ~ 45 psi which is enough pressure to drive two kegs.

if you use air pressure via a compressor it would not be unreasonable to assume ~120 psi which is 4 kegs. if you want to be able to drive more kegs you can attach more kegs to the high pressure keg with two manifolds, in to in out to out.

its just my latest brain storm, if I had the spare kegs I would do it