Semi-Continuous Cryogenic Ethanol Process Flow Diagram

Hello All,

I think this is my first original post…can’t remember…

At any rate, I’ve been working with a chemical engineer (shoutout to Gokberk for all his help in generating this!) to develop a PFD (process flow diagram) of what a semi-continuous cryogenic ethanol extraction lab would look like.

I say semi-continuous because the plant material input it batch. Everything else is written as continuous flow (even the carbon filtering!).

A couple of points before we get started:

  1. I know there are other ways to extract/filter/distill, not everyone likes ethanol
  2. I plan to create more of these documents for other types of extraction in the future (butane, propane, CO2, etc).
  3. It is possible to create beautiful, water-clear distillate without carbon washing or bleaching. I am merely illustrating a very popular method for clarifying.
  4. This model is meant to illustrate a very popular, scalable method of extraction to distillation, NOT to say this is the “Best” way to do things.
  5. I chose to mark the ethanol from de-solvation as “Waste” due to the cumbersome task of integrating a fractional distillation recovery system in the current market.
  6. This is a QUALITATIVE PFD. That means it doesn’t have all the nitty gritty for a proper simulation. Quantitative to come!

I hope we’ll get some constructive feedback on the PFD and suggestions for improvement.

Kind regards,



Wow, beautiful stuff as always Lilibel.

couple notes
-removing all particulate and semi-solubles is important for max decolorization efficiency, normally at least. Im sure you meant it, but I would put a secondary separation step between 1 and 2
-Holding vessels in between each step
-Bulk evaporation isnt limited to falling film. (splitting hairs I know)
-Secondary solvent stripping step, bulk evaps more fun when you can run it quicker and have a secondary device to pull lasting solvent
-post distillation procedures eg. liquid separation, filtration, decoloraization


This looks very similar to mine, only much more detailed and well laid out - mine stops at basically the evaporation step as everything after that is designed to be a separate process in our setup.

Decolorization shouldn’t really be necessary with -86 EtOH? Though filtration of some form will likely be necessary.

I like the LN2 cooling vs the chiller/heat exchanger setup we’re currently planning on using. Much simpler, all things considered.

@Psilisophical has a good point with the holding tanks (and everything else), that’s something I’ve missed in mine as well.

1 Like

Looks like my diagrams but mine have valves, spec reference sheets, and all the other little details that are needed to actually piece out a build.

Then again I charge anywhere from $350-500/hr per consult and almost always require either some equity deal or advisor role.

These PFD’s are often borderline P&ID’s and play hand in hand with laying out large process scale facilities. With most jurisdictions requiring closed systems, it is becoming more and more common that I have to develop diagrams for fire marshals, for my various clients CUP and final planning phases.

Looks good to me, somewhat vague, but nicely laid out, though!


@Cannachem This is a qualitative PFD. We are planning a quantitative one as well. Our hourly rate starts at $700 for the first hour followed by $500 for each remaining hour. I will add that to the preliminary comments thank you!



Thanks you brought some points I was musing on last night…especially about the holding tanks.

I think I’ll add holding tanks between all the steps, but for between falling film and de-solvation, add a stirred holding tank (jacketed heated) to aid in the degassing and decarb. What do you think?

Bulk evaporation- any other suggestions? Falling film seems to be very popular these days. Ace has ideas for a super sonic “spray-vap” (but not spray vap) style insta-desolve…

Secondary solvent- So did you mean something prior to the first stage of the triple-distillation?


You’re probably right, decolorization should be an optional aspect, but that filtration should be a step of some sort.

I suppose it could be changed to a holding tank with stirring and reaction ports just in case its desired to apply adsorbent.

If you have a 3 stage distillation isn’t the 1st stage for volatiles anyway
Edit : it even says that lol

1 Like

Decarb tank is key since its suvh a time dependant reaction, od place it after total solvent removal

Rising films work well for evap, rising/falling series ftw

Secondary solvent meaning a mixing tank and filters for something like alkane-assisted polishing of the first pass distillate


Yeah I definitely need a decarb tank in there; I’ve used falling film, desolve—>terp strip passes to decarb before and its been alright, but I think (theres some math to be had here)…some things to consider are:

  1. Is the residence time in the falling film, 1st stage of distillation (volatile), and terp strip, enough to decarb fully and if SO… is that time shorter than a holding tank that is stirred under vacuum with heat?

  2. Or perhaps the falling film ----> stirred reactor can decarb and take care of residual solvents at the same time? There would be a huge gas load and it would take “longer” however it wouldn’t be moving from tank to tank. I like the idea of desolvating on a thin film to avoid pockets that get “stuck,” if you will.

Rising falling film I found:

Something like that^^?

Secondary Solvent

This is a good one…I’ve got a lot of ideas here.

  1. There could be a reactor section for slurry pesticide removal and polishing in alkanes.

In your scenario of polishing this is what I’m seeing:

1st pass distillate—>Reaction vessel, alkane solvent and adsorbent w/ option for liquid liquid extraction----> Filtration—>Settling tank ---->liquid separator----->drying process, possible reactor with adsorbent (MgSO4 or Zeolite) slurry or Zeolite packed column -----> Filtration---->solvent recovery-----2nd Pass Distillate.

1 Like

As @Cannachem mentioned, it probably looks like many of our initial PFD’s. I recommend including the heating and cooling loops as well - though it makes it tougher on the eye to look at. A lot of people will totally forget you need hot/cold sources no matter how many times you verbally mentioned it. This PFD might lead someone to believe that all the major components are accounted for - though none of the heaters/chillers are represented (besides the initial LN2).

Agreed. I am working on a buildout right now that is likely incorporating more rising film evaporation than falling film. I think rising film will have better thermal transfer, but with slightly slower flow rates - given that all other factors of heat exchange remain the same. In other words - it will cost less but will take longer to operate per volume of solution.


I’ll be adding more detail into the quantitative version.

1 Like

Wait till you see the SF spot lol

what brand zeolite and Å size?

Hi @Lilibel, this is a great PFD. I know this is from ProII Simsci simulator. I’m trying to simulated the process. I made the molecules of cannabinoids by using unifac structure. But to get a better simulation I wanna khow if you simulated the whole plant. Also, I have the kinetics of the descarb to put it in a reactor.