You want to flow low pressure Co2 counter current to the crude. At below 400psi the liquid Co2 will only remove the lighter compounds from the crude. At the same time the heavy less soluble compounds will drift to the lower portions of the reaction vessel.
The lower portions of the reaction vessel will contain the less soluble heavier more polar compounds (ie THC-A).
By removing the lower portions of the reaction vessel through a filter using rapidly decompression you will quickly crash out the THC-A and create snowflake crystals. The key to high purity is to insure the crude is fully dewaxed before the reaction. Any wax will fall with the THC-A in the counter current flow and end up crashing with the THC-A in the filter. You can clean up the percipitate by flushing liquid Co2 through the filter to wash them of impurities. Ideally this is done at pressures below 600psi.
Waxes crash out at pressures below 650psi, just like with the THC but at higher pressures. If you decompress through a filter the waxes can be removed inline. This only works with a CXE solvent mixture. Pure Co2 will just clog the filter and make a mesa.
1% to 3% ratio ethanol to Co2 during extraction and 10% to 30% ration ethanol to Co2 during the dewaxing filtration. The delta P comes into play also, the JT cooling of the CXE mixture is responsible for the rapid percipitation of waxes. Having a higher pressure vessel to expand lower pressure vessel using a needle valve can cool the CXE solvent mixture to below -20f in seconds.
The ethanol at this point is no longer a modifier but a process solvent and the co2 left in the CXE mixture is a antisolvent.
Are you saying you dissolve the extracted material in the 10-30% EtOH in CO2 then allow it to rapidly decompress and through the JT cooling effect the waxes percipitate and you filter that now largely EtOH solution for a mixture that is ready to have THCa crashed out of it??
No I extract at low moles and then recover most of the Co2 until I get the desired ratio in the CXE mixture. Then I simply use a delta P to create flow through a needle valve and then a filter.
Okay thank you, I believe I am clear on this part now. So after you’ve dropped pressure significantly through needle valve and filtered you are left with your filtered extract in mostly ethanol. From here how do you get the THCa to crash out as you were mentioning before?
The only way I use CO2 is in its’ supercritical state, and I can reliably produce crystals with just that.
Edit: The key is phase change, rapidly decrease pressure on a solution containing THCa and the phase change will cause the THCa to crash. Doing this multiple times equals larger formations.
Not at the moment… I’m in the process of contacting a couple of engineers to try and develop an inline crystallization vessel. If that doesn’t work out I’ll dump all of my info on here.