Making Dry Ice from scratch
1,573,059
Published 2023-03-09
as liquid to form ice.
There are several ways to produce CO2 - a few of these are:
-Reacting acid with baking soda
-Cooling and collecting exhaust from combustion of hydrocarbons
-Capturing exhaust from yeast as it consumes sugar
-Capturing human breath
-Dissolving atmospheric CO2 in water and extracting it under vacuum
-Reacting atmospheric CO2 with Calcium Hydroxide, creating Calcium Carbonate, then decomposing the Calcium Carbonate to release CO2 and Calcium Oxide. The Calcium Oxide is later regenerated back into Calcium Hydroxide with sodium hydroxide.
Once the CO2 is captured, it has to be stored. In theory, large gas bags could be used, but that's not very practical, so i used a fridge compressor to force the captured gas into a compressed air tank at ~160 PSI (about 12 bar). Using a 10 gallon (38L) tank, i stored approximately 1.8 lb (0.82kg) of CO2 gas.
However, to freeze CO2, it first has to be liquified by either high pressure, very low temperatues, or both. To liquify at room temperature around 25C requires about 60 bar of pressure (~867 psi), but my compressor was only capable of producing about 400 psi (about 28 bar). In order to liquify the CO2 at this pressure, i had to put the tank in an ice bath at 0C.
Even this wasn't quite enough, though, so to get a little bit of extra pressure, i fed the output from the 12 bar tank into the suction side of my compressor, allowing it to produce close to 600 PSI at the discharge side. In the ice bath, this was enough pressure to liquify the CO2, but it took a little over an hour to transfer and condense the CO2 from the 12 bar tank. I collected about 500 grams of liquid CO2 in the high pressure tank.
Once I had the liquid CO2, i turned my high pressure tank upside down so that the liquid would come out first, and discharged it. Liquid CO2 can't exist at 1 atmosphere of pressure, so as soon as it comes out of the tank, it flash freezes to dry ice at -79C.
The tricky part is capturing the frozen CO2, since most of it blasts out into the atmosphere. The container being used to capture the ice needs to be vented to work properly, but not vented too much, or else all the CO2 will be lost. To do this, I tried a sock (effectively a porous container), which probably collected less than 20% of the CO2 from the tank as ice, and came out in a fine powder, meaning it didn't last long. The second approach used a mold with velt holes, but i only recovered about ~2% of the CO2 this way.
I think the key to creating a block of dry ice is to discharge relatively slowly into a mold. I had my valve full open, and I think instead of allowing ice to collect and settle in the mold, the flow was blasting it out.
Ultimately, the time and cost of producing the dry ice from scratch make it impractical as a pre-cooler for liquid nitrogen generation.
Music Used:
Kevin MacLeod - Lobby Time
Kevin MacLeod - George Street Shuffle
Kevin MacLeod - Groove Groove
All Comments (21)
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For those who are curious, the "KSP Soundtrack" is "Groove Groove" by Kevin MacLeod. Kerbal Space Program used several Kevin MacLeod tracks for their music in early development because they're royalty free, and left them in the game even after they started producing their own soundtrack music.
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I used a very simple dry ice puck maker designed for special effects use. It was two disks of wood with velcro hook strips glued and stapled on them, and a pipe connector tapped into one the disks. In use, a larger velcro strap was applied around the two disks with a gap for the puck of dry ice to form inside. Then liquid CO2 was blown in until the puck started making slight creaking noises. When the velcro was undone there was a nice solid puck of dry ice inside. That was an impressive way of making enough CO2. I wonder if the first compressor was angry about being started under pressure, since they aren't really designed for that.
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"It could eeeasily be lethal... Anyway" Stay safe!
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I love the carefully included humour and educational value of your content.
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It is always surprising how we tend to overthink things. My friend runs a bug killing business and we were trying to think of a safer way to kill the bed bugs (zero chemicals) and not make his insurance jump through the roof (Heat Treatment). Bed Bugs are attracted to the CO2 we produce and are mostly nocturnal. They cannot grip certain surfaces. So, we could easily find a dog bowl and scuff up the sides of it so the bugs can get in. Put a cylinder of dry ice/CO2 making stuff in the middle with a small bit of water to further help trap the nasty bugs. A simple drip mechanism of Vinegar into Baking soda will do just that. Slowly create CO2 so the trap can be run for extended periods of time.
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This is so underrated. C'mon, this stuff is much better that all of pop-science channels put together
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Your DIY chemical engineering is so awesome and inspiring. I’ve studied this stuff in school, yet between all the thermodynamics, transport phenomena and kinetics classes, I can’t think of a better way to demonstrate the spirit of engineering than what you’re doing right now. Keep up the good work!
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3:32 - You need to add an air stone diffuser to your bubbler/scrubber to reduce sloshing and improve absorption of fumes and such. The sloshing is depleting your desiccant capacity too quickly as can be seen with the dripping into your drier. Also add some salt to your ice bath for a few extra degrees of cooling. You can get down to -21C with enough salt, reducing your pressure requirement for condensation down to just 19 bar.
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I am so used to watching Nile Red and all of his proper glassware and then I find you... I sub'd the second I saw the gatorade bottles as test equipment. Now I know we are about to learn some sketchy fun stuff. This is how I experiment in my garage too. Sometimes you just want to learn but don't have every single part so you just make it out of normal household goods.
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I work at a big box store in the plumbing department. Sometimes we get people trying to do such creative projects. I'm glad that you understand the danger. Thank you for allowing us to live vicariously with your videos! Stay safe!
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I remember seeing in a science equipment catalog, maybe Edmund back in the day, a dry ice sock, the use of which I never explored. I hadn't thought about that in probably 20 years or more until you tied the sock to the outlet. "Hey, so that's how it works!"
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As someone who fills cryogenic liquids, the lack of ppe is both realistic and terrifying 😂
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you’re level of ingenuity is inspiring!! definitely got yourself a new subscriber!🤘🏽
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Seems to me like you chose the grippiest material to gather dry ice onto. Thin pillowcases perform much better and its easier to get the dry ice out of them, also dry ice packs rly nice, so u dont have to go straight into pellets. I also think a 3D printed nozzle of some kind could help with creating more snow.
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Testing the co2 by extinguishing flames is essentially the mechanism by which welding gas works. Keeps the oxygen out to keep the metal from burning and reacting with atmosphere making oxides and shit. Argon does that also but also assists in maintaining an arc.
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Your Embraco is a R134 refrigerant. In order to reach high pressure you should use a R404 or R410 refrigerant type of compressor. Danfoss series SC12CC or SC15CC. Also preferably look for a "medium back pressure" as they are suited for higher current through the stator. Putting current through the stator without the rotor running results in no counter EMF (Electro Magnetic Force). Every stator will burn if you do what you did. Notice that all hermetic compressors are protected with a bi-metal current limiter. So the click you heard probably is the over current protection, which will reset itself automatically. When you start experimenting with ethylene, make sure the first trap is at least -30'C, otherwise pressure will be too high. Use preferably R410 in your first stage. For the second stage you will be unable to find an expension valve. You can only run this stage using capillary. It is a long way to get a two stage system working from scracttch or know-how. You can reach me via linked-in, Roland van Hall - Tamson Instruments.
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At a guess, motors often have lower torque starting up than when running, the compressor got to a high enough pressure that while it could still run, the load was too high for the motor to be able to start again, it stalled and instantly burned out.
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I was fearing another silly video with no redeemable science - but instead got physical chemistry and a wealth of information about bodged together pressure fittings! Now, all you needed to do was add some salt to the ice to further lower the temperature below 0C and you would have made my day! Thanks for sharing this! (btw, I'm a p chemist by training - very well done!)
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Those little compressors are usually cooled by "cold/cool" refrigerant in the return/suction. It was probably working so hard windings got hot and shorted. Like others have said, lubrication is important too.
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Utterliy fascinating project! Thank you for going through all that and sharing this with the world!
