Falling Film Evaporator

Falling film evaporator is very fast at recovering ethanol after extractions, however, there are a lot of details I can’t seem to find an answer for.

  1. DeltaSeparations claims to recover up to 90% solvent. What happens to the rest 10%? Does it evaporate through an outlet in the pump, or does it remain in the crude extract?
  2. I know that for ethanol extractions we acquire water from cannabis, which is not desired. Can FFE evaporate only ethanol (at best 95% pure ethanol), or will all the collected water from cannabis result in recovered solvent?
  3. And lastly, (assuming no solvent remains in crude after FFE) how do we remove the oil from FFE without breaking vacuum?

Thank you!

  1. The last 10% stays in the crude, since that model (as are most others) is a single stage evaporator. If you take 100% out, moving the crude gets extremely difficult. Most guys finish in a roto or in their decarb reactor. Big boys finish in a second FFE or use a multi staged one.

  2. Water forms an azsotrope with the ethanol, eventually watering down that ethanol so much it starts pulling excessive chlorophyll and need sto be reproofed or replaced

  3. Gear Pumps, typically.


Thank you!

As for 2., yeah, it is azstrope, but in theory you could pull 95% pure ethanol if the temperature is set right. Is it not achievable in practice?

It’s a combination of temp and vac that will increase its efficiency. (Less ethanol left behind)

Pretty sure you need more than just temp to break the azeotrope at a certain point, let’s get some chemist input?

I know a lot of reproofing stills use zeolite for this

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You need a third substance like benzene to break the azeotrope
at 95.6 % they are inseparable by distillation of any kind

something about raults law

chem e not a chemist…


I always thought proofing up was more important for extraction efficiency then for chlorophyll and sugars

I was always told alcohol starts loosing its extraction efficiency once you get more then 5% water in there

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This isnt true

Membranes ftw

We’re proofing up ethanol from 93-99% using membranes

Look up vapor pervaporation

membrane science is so cool I have been following ur journey on insta.

we had a engineer come in from fair life when i was in school, they separate every portion of milk with membranes and then they mix back as desired!

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Tbh if I wasn’t in hemp / cannabis I’d probably do nano filtration

Shits beyond interesting to me

I wonder if that’s a factor of cannabinoid solubility or if it’s more of a solvent saturation issue (the chlorophyll is taking up space that otherwise would have been filled with cannabinoids)?

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Membrane desalination is likely going to be world changing


The membrane company im working with has figured out a way to improve RO filtration to efficiencies above 95% from 42% using membrane distillation

Pretty much you take the waste stream from RO and do something called membrane distillation which is where you distill the water through a special hydrophilic membrane that won’t let anything else through.

We use to just throw the waste stream of RO away because it’s so dirty, this allows us to save that precious water and utilize it while using solar energy to do it (yes, that’s right SOLAR)

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That same company has also figured out a way to coat steel with there membrane coatings so we can have sintered disc membranes…

Imagine a membrane sintered disc before your crc to do all the heavy lifting…

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Or how about making h2 using water and methane using a ceramic membrane coated with palladium?

Imagine being able to do dehydrogenation reactions on thc inline using a membrane xD



A small portable membrane I could piss in to reclaim my own water, for survival scenarios?


They already make that straw thing, the one that Matt Damon gives out in Africa

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azeotrope is at 95%EtOH/5% water, and you can break it with molecular sieves.


If you’re freezing biomass before extraction and keeping ethanol sufficiently cold before & during extraction you’ll pull considerably less water than extraction at room temps. Over time doing room temp extraction with reused ethanol will result in lower proof as it continues to pull water from the biomass and ambient moisture in the air.

The amount of ethanol left over in the output crude after the FFE is dependent on a bunch of factors, not the least of which are design of the FFE, vac level, ethanol mix injection temperature & atomization, FFE hot side loop & process temp and cold side loop & process temp. Within reason we usually adjust the hot side loop temp and vac level to achieve a desired output viscosity, as Future said moving pure crude is a pain in the ass, as well there isn’t an FFE on the market I’m aware of that has sufficient residence time with heat to fully decarb your crude in a single pass, without the decarb step it makes distillation a real headache.


molecular sieves ftw