I am running a 6" Chinese-made wiped film distillation unit for CBD distillation. The first crude we ran through it ran like a dream. A bit of tinkering with the settings and with 183C evaporator, 70C internal condensor, and a 15ml/min feed rate we were able to get 75+% yields of ~85% CBD honey-colored distillate on the first pass. We pulled over 96% of the CBD in the crude to the distillate. The pressure while running was about 90 mTorr.
We then got some crude that was extracted with CO2. This material required 5-6 passes of the crude/waste fraction to get a decent yield of distillate. The lowest pressure we could get on the first runs were over 300 mTorr. The pressure decreases with subsequent runs. We chalked it up to an issue with the crude.
However, we got some new crude this week and things have gotten worse. The pressure in the unit is high while running and our distillate yield on the first pass was about 5%.
My best guess is that the crude isn’t completely decarbed and that the CO2 that is offgassing it raising the pressure, thus interfering with the distillation. @Munkdooligan had some of the previous crude tested after I sold it to him and it came back as having 6.5% CBDa. I only have a GC and I haven’t tried derivitization with it yet, so I can’t test for CBDa content. I sent some of the new crude off to the lab.
Today we ran a bit of the crude left over from the first batch, the distillate came out darker than before (like very light maple syrup), but otherwise it ran like it did originally, ruling out any hardware problems.
Could CBDa releasing CO2 be the problem with my system? Anybody have any other ideas?
CO2 crude generally requires 2 passes through wiped film units. CO2 extracts have water and monoterpenes that have to be stripped in the first pass, then cannabinoid distillation happens in the second pass.
The old crude was ethanol extracted. The second batch of stuff was CO2 extracted. We found that we had to run it through once at a higher feed rate and lower temperature to remove terpenes and acetic acid. That run isn’t even counted in the 5-6 passes.
We figured that the new crude would work much better because it is also ethanol crude. However, it is exhibiting even greater problems.
It is dewaxed. It is supposedly decarbed (although at least the last stuff wasn’t completely decarbed). I don’t think the first crude we used was completely dewaxed. It made a mess in the evaporator, but it distilled well. Haven’t messed with the pH. I didn’t know that the pH was a relevant variable.
Are you going straight from crude to distillate without doing a terpene strip first? First pass in a WFE is usually a terpene pass and only pulls terpenes. Its done at a lower temp to not pull any cannabinoids. If youre not doing this thats your problem. Your purity is really low for a WFE which makes me believe youre not hitting proper vacuum level because youre not stripping terpenes first
For the in first batch of crude we didn’t strip terpenes. We just ran it and it worked out great. We ran the CO2 batch through the WPE at 150-160C. This pulled pretty much all of the terpenes out. The most recent crude didn’t get special has been run through the unit at 183C three times, some terps came out the first pass, but by the third batch of crude, there weren’t any more terpenes being collected and the problem persisted.
What temps are you running on your evaporator? You shouldnt need 3 passes, 2 max. Are you running the same temps all 3 passes? Usually when i run the root science VTA we decarb in a reactor under vacuum at 150c till no bubbles are present. Then we do a terpene pass at around 152 c on the evaporator. After that the thc pass is around 172 c on the evaporator. Do you have a difussuon pump on your system? Are you using it only second pass?
