Liquid CO2?

[Thanat0s]

You may have just set a record for off-topic-edness.

Still not totally clear here, but you could mix liquid CO2 with liquid sorbet under high pressure. At these high pressures, the CO2 can be at equilibrium as a liquid. Then supercool the liquid to solidify the sorbet. At this point, the CO2 is dissolved in the liquid. As it melts, the CO2 would come out of equilibrium and make the sorbet appear to boil. I am not totally sure if it will work, but it is sound in theory. (I do know the same process is used with plastic and when heated to a softening point, the plastic bubbles up. Unfortunately, sorbet isn't particularly rigid and may be near its softening point at freezer temps. You may have to store it in especially cold freezers...like Dippin' Dots! Probably couldn't sell it in the supermarket, though, because it would likely soften on the way home.)

Good luck in your endeavors and be careful.

You raise fair points!
Also, I was considering doing that with mixing them, but the only problem is that I would think that would use too much liquid CO2 at once. Go back 1-2 pages and read the MIT study on carbonated ice cream.

 

[Thanat0s]

Also, could I use a Venturi chamber to mix the liquids?

 

[freisste]

You raise fair points!
Also, I was considering doing that with mixing them, but the only problem is that I would think that would use too much liquid CO2 at once. Go back 1-2 pages and read the MIT study on carbonated ice cream.

I think it would use as much as you meter into the mixing chamber. I read the MIT thing last night, so I don't remember exactly what it said. I think a 1:1 ratio was optimal. Not sure if that was a mass ratio or volume ratio, but you should probably experiment to find the optimal point for your application. At any rate, you should be able to dictate the ratio in your system. It would be easy in a batch process. In a continuous process it would be more complicated but likely not impossible.

 

[freisste]

Also, could I use a Venturi chamber to mix the liquids?

Possibly, but keep in mind venturis rely on a low pressure area caused by movement of material. "Low pressure" is a relative term here as it will all have to be high pressure. I think you would be better off with a batch process where you added a certain amount of material to a mixing chamber, sealed the chamber, pressurized (maybe with an initial charge of CO2, but more economically with a mechanical press - almost like a hydraulic cylinder works), then forced liquid CO2 into the system before mixing. Then cool the entire chamber, release the pressure, and remove the carbonated block of frozen goodness.

That's my best off-hand idea, anyway. You are still probably better off with nitrogen. With nitrogen, you don't have to worry about the high pressure cylinders and you can pour little bits on yourself and coworkers. It freaks people out, but really isn't as dangerous as it seems. (Man I miss the days in the chemistry lab)

 

[Nonyaz]

Another concern is the pressure referenced in the mit article is 576 psi. I would be greatly worried about the pressure vessel becoming supercooled and having its elasticity drop to about the level of a saltine and shattering/exploding in a spectacular fashion. I would suggest you have an engineering firm design that part along with any fittings attached to it. That way you have a PE signing his name to a piece of equipment that he/she guarantees to operate in a specified temperature range/pressure.

 

[RobertRGeorge]

I'm very late to this conversation but I must say that while many people oftentimes want to be helpful if they can, this is a heck of a bad place to be getting detailed engineering consulting for the design of a device that seems to have the potential to be extremely lethal. Just my opinion.

 

[Thanat0s]

Possibly, but keep in mind venturis rely on a low pressure area caused by movement of material. "Low pressure" is a relative term here as it will all have to be high pressure. I think you would be better off with a batch process where you added a certain amount of material to a mixing chamber, sealed the chamber, pressurized (maybe with an initial charge of CO2, but more economically with a mechanical press - almost like a hydraulic cylinder works), then forced liquid CO2 into the system before mixing. Then cool the entire chamber, release the pressure, and remove the carbonated block of frozen goodness.

That's my best off-hand idea, anyway. You are still probably better off with nitrogen. With nitrogen, you don't have to worry about the high pressure cylinders and you can pour little bits on yourself and coworkers. It freaks people out, but really isn't as dangerous as it seems. (Man I miss the days in the chemistry lab)

I don't think I have the resources to create an intensely high pressure vessel to compress the mixture.
What do you mean by Venturis relying on low pressure? I just need to spray the liquids together to mix them.

 

[wolfstar]

You're not getting it. Liquid CO2 won't come out. Gaseous CO2 and solid CO2 will come out and the solid will be a VERY small amount...and will almost instantly sublime (its like evaporating, but it is solid to gas instead of liquid I gas).

It only goes from one tank to another as a liquid because both tanks are pressurized.

Also, someone said that soda fountains are water, CO2, and syrup, but I'm pretty sure they are carbonated water and syrup...

I said that. The soda fountain at your local fast food joint is hooked up to 4 things, tap water, a co2 tank, a bag of syrup (bag-in-the-box),and electricity.

The water is carbonated in the machine (but the water comes from a municipal supply line) , and is then mixed with the syrup right before it leaves the nozzle and enters your cup.

 

[freisste]

Hmm. I must have misunderstood how they worked. I always thought that they were carbonated water tanks, not CO2 tanks.

This isn't a first, I doubt it will be the last.

 

[wolfstar]

You may have just set a record for off-topic-edness.

Still not totally clear here, but you could mix liquid CO2 with liquid sorbet under high pressure. At these high pressures, the CO2 can be at equilibrium as a liquid. Then supercool the liquid to solidify the sorbet. At this point, the CO2 is dissolved in the liquid. As it melts, the CO2 would come out of equilibrium and make the sorbet appear to boil. I am not totally sure if it will work, but it is sound in theory. (I do know the same process is used with plastic and when heated to a softening point, the plastic bubbles up. Unfortunately, sorbet isn't particularly rigid and may be near its softening point at freezer temps. You may have to store it in especially cold freezers...like Dippin' Dots! Probably couldn't sell it in the supermarket, though, because it would likely soften on the way home.)

Good luck in your endeavors and be careful.

Good post...I would expect it to blow up like a frozen marshmallow under vaccum if he gets the co2 dissolved enough.

 

[Cambone]

Why do I feel like this thread is one elaborate troll?

 

[wolfstar]

I don't think I have the resources to create an intensely high pressure vessel to compress the mixture.
What do you mean by Venturis relying on low pressure? I just need to spray the liquids together to mix them.

You realise of course that the quantity of actual liquid co2 you will need for a palatable amount of carbonation is extremely small in relation to the quantity of your product. If you think about it, a 5 pound co2 tank is good for about 20 5 gallon kegs of beer, give or take a few depending on style and other factors.

You might be better off carbonating your mixture by traditional means while it is still liquid, then freezing it under pressure to keep the co2 in solution.

 

[BrewThruYou]

Get a samarai sword (Hanzo hopefully) and chop the co2 tank in half and pour out all that liquid co2 goodness from the bottom half.

 

[Thanat0s]

Hm. I don't think I have the resources to create a pressure vessel as described. I'd rather not do it in batches.
I suppose I'll go find an engineer for advice. If anyone has anything else to contribute, let me know!

 

[porcupine73]

Not sure if this helps, but there is information about there about using liquid co2 to do drycleaning. Obviously they have to keep the pressure high enough to prevent it from solidifying, but maybe you pick up one of those machines secondhand and modify it for your purposes?

 

[mattd2]

Well, I'm essentially going for some sort of carbonated sorbet. The MIT project that was posted has the same application - liquid CO2 being sprayed/mixed against the mixture to carbonate and freeze it.
How do I do it, then?

What is a carbonated sorbet?All I can image is a mess with bubbling slushy popping all over the place
As to how to do it, if you don't know how to do it yourself you need to find someone who can - either a professional proces engineer ($$$$$$$) or go to you local Universities engineering school and try and find some process engineering student (warning they could potentially know as much as you)

If I had to guess I would imagine it to look something like this (with controls to get the flowrate of the liquid to match what the CO2 is doing / CO2 flowrate fixed by designing the oriface appropriatly):

 

[Gabba]

Why do I feel like this thread is one elaborate troll?

Either a troll or an interesting obituary in the making

 

[Thanat0s]

I'm actually completely serious. But it would be an amazing obituary, I have to admit.
"MAN KILLED BY DELICIOUS DESSERT"
As for the above diagram, that's what I envisioned too, I just need to figure out the details of effectively combining the liquids.

 

[Thanat0s]

You might be better off carbonating your mixture by traditional means while it is still liquid, then freezing it under pressure to keep the co2 in solution.

Right, but would the carbonation be efficiently contained? That's my concern.

 

[Thanat0s]

I think part of the appeal to doing this with liquid co2 is the interesting mouth feel that it creates.

 

[Camping57]

The entire process needs to be conducted in pressure vessel in order to carbonate the sorbet. It would need to be similar to a sorbet keg! The slushee stufff needs to be able to absorb the CO2 and then not immediately lose all of the carbonation. You will have to maintain the finished mix under pressure until it is served in order to keep any dissolved co2 in the mix.
With the correct cryogenic alloys your mixing equipment won't blow up, but then those alloys aren't cheap either.

 

[Thanat0s]

The entire process needs to be conducted in pressure vessel in order to carbonate the sorbet. It would need to be similar to a sorbet keg! The slushee stufff needs to be able to absorb the CO2 and then not immediately lose all of the carbonation. You will have to maintain the finished mix under pressure until it is served in order to keep any dissolved co2 in the mix.
With the correct cryogenic alloys your mixing equipment won't blow up, but then those alloys aren't cheap either.

Hm. MIT disagrees.
I have to conduct further research.

 

[freisste]

I think part of the appeal to doing this with liquid co2 is the interesting mouth feel that it creates.

Obviously this is an opinion, but Guinness uses nitrogen which (IMHO) is more interesting than carbon dioxide. It is going to be basically boiling either way ...

 

[mattd2]

Obviously this is an opinion, but Guinness uses nitrogen which (IMHO) is more interesting than carbon dioxide. It is going to be basically boiling either way ...

I think you meant to say, Guinness pour through a stout tap or with a widget in the can/bottle....

 

[Thanat0s]

Obviously this is an opinion, but Guinness uses nitrogen which (IMHO) is more interesting than carbon dioxide. It is going to be basically boiling either way ...

How do they carbonate it without carbon dioxide?

 

[freisste]

My understanding was that they used nitrogen instead of CO2. What's the difference? It is a gas dissolved in a liquid which is in equilibrium under pressure, but when the pressure is released (when you open the bottle, can, or pour from a keg) the gas comes out of solution.

I don't know.... Maybe they use CO2, I was just under the impression that they used N2.

 

[mattd2]

AFAIK most kegs are purged after cleaning with nitrogen (again it is cheaper than CO2), beer is CARBonated with CO2. When the keg arrives at the pub they hook it up and push the beer out with beer gas, a mix of CO2 and N2. Most pubs need to use beer gas anyway since the lines from the keg cooler to the bar are so long they require the head pressure on the keg to be above the normal carbonating pressure. What the bee gas does is allow for the high pressure but since it is only partly CO2 the beer only "sees" part of the total pressure as CO2 (so you can have the pressure up at 50 PSI but the beer only sees 12 PSI of CO2 on it). Nitrogen will not disolve into water as easily as CO2. Stout facuats have restritor plates in them which intentionally breaks the CO2 out of solution (it's like when you drink Coke with a straw - it is more fizzy), the downside is you need a high pressure to push the beer through the stout tap = you need beer gas.
The widgets are another tech story which involves them droping a bit of liquid nitrogen into the can/bottle just before the seal it up.

 

[freisste]

Cool. Thanks.

 

[RobertRGeorge]

Hm. MIT disagrees.
I have to conduct further research.

You know Thantos, I'm beginning to wonder if that may be your real name. Again, just my opinion but it seems to me that this is probably not the kind of research one would reasonably want to do on the cheap.

 

[mattd2]

Hm. MIT disagrees.
I have to conduct further research.

I skimmed the MIT paper and I would say that they actually agree with Camping57!