I am using a large scale CO2 extraction machine to extract CBG from hemp. Lately i have been having issues with dry ice forming in our vessels ( where we put or biomass) and the extracted crude freezing in our separator ( where we actually pull the material out).
So far, during the extraction run i can pull crude out of the separator through our needle valve up to about the 75% completion mark. Im confused on how were freezing the crude up while its dropping out into the separator. We have a second separator for our light fractions which has not had an issue with freezing, only the first heavy fraction separate.
Our temps are about 40C and our pressure is well over the amount needed to reach a supercritical state. At first I thought it was an issue with depressurizing but im at a loss now.
I recently did an ethanol clean and ran about 40 gallons though to clean out any built up residues and have been having issues following that. I thought maybe some water was in the machine still from the ethanol being cut with it but I think most of its gone. Could it be as simple as water still trapped in it or could it be the CBG? I ran lots of CBD without issues but that was before my big clean as well.
Any input or suggestions would be greatly appreciated.
Where do you think it’s freezing up?
What machine are you using?
Dry ice formation is generally caused by too dramatic of temperature/pressure change. If you have warm/hot liquid CO2 that rapidly decompresses it will turn to dry ice because of the associated temperature change.
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Its a 2x360 liter extraction vessel.
That was my first thought but it seems to happen part of the way through the run without any large changes so i figured it had to be something else.
Its getting from the extraction vessels all the way to the separator before freezing so I guess its got to be at some point while it sits in the separator before we get it out.
what temperatures and pressures are your extraction vessels at during the run? if you say youre in the supercritical state, than the only way you are forming dry ice is if theres a leak. like @ExTek90 said, big pressure drop.
what temperatures are your collection cyclones? those are certainly liable to clog, especially late in the run as you are seeing, thats primarily due to the fact that in the beginning you had a lot more terpenes (read: co-solvent) helping move things along.
water ice is definitely a possibility, especially with cbg (wet?) material, but obviously not 40c lol.
can you run a bit hotter? that will almost certainly fix your problem.
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Either your regulator is icing up (always a possibility) or your cyclone vessels are too small for the amount of extract you’re producing. Dry ice likely is forming from the start of your extraction, but it’s not at a critical mass to impact flow until later in the run.
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What pressure and temperatures are your extraction vessel and first collection vessel at? Also, your material should be dried to 5-10% water content if possible. If you’re actually in the supercritical state, the solution should be too hot for wet or dry ice to form.
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Interesting. That makes a lot of sense.