One thing I think people miss alot when talking about increasing the amount of biomass in an extraction vessel is the cycle time should increase as the available compounds do. The cycle time is based on the amount of available compounds that you are targeting. If you fit 50% more of the same biomass in an extractor it should have 50% more Co2 cycled through it.
Understanding this also explains why a Liquid Co2 extraction is faster than supercritical. The Liquid Co2 does not seek Fats, Waxes, Lipids, Water and plant pigments whereas SCFE does. This increases the targeted compounds by 100-200%. When the Co2 is pulling up to 3x the compounds it takes 3x the Co2 to pass through the material, and 3x the time. This is the minimum amount, as the Co2 doesn’t return to the extraction vessel in pure form. SCFE as the systems available today perform it, leaves VOCs entrained in the gas phase to the condenser for liquid pumps and to the pump on gas pumps. Co2 entering the extraction vessel that is already partially loaded with compounds can not extract as much per pass as pure Co2. These VOC also act as a co-solvent and effect the process.
Imagine that Co2 is a subway train. The subway station needs to move 100 people and each train holds 50 people. The train that comes to the station empty each time will only take two trips. A train arriving half full to the station each time will take 4 trips. Twice as long to move the same mass. Using the same analogy, what if there was 100 targeted people, and another 200 non targeted people to move (ie. wax, water and plant pigments). The train that only allows the targeted people, is far more efficient. Still 2 trips for the “empty / targeted” train, and 8-12 trips for the “loaded / non-targeted” train.
The Separator on SCFE systems is to separate the extracted compounds from the Co2, so the Co2 can be reintroduced to the start of the process. Ask yourself this. If separator 1 worked, why would separator 2 have anything in it? If separator 1 didn’t completely work did #2 or #3.
You can say Co2 does or doesn’t work. However you should really talk about individual Co2 processes and their effectiveness. This has been a mute point as most the systems on the market are a copy of the same copy.