Converting passive closed loop system to (semi) active system + CRC

Hash and Stuff Solvent Recovery
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Hi,

i recently aquired a passive closed loop system for bho extraction, works like a charm, even better i also got a 2nd System for free.

But since dry ice is quite hard to get here and i can only work with ice + salts, i would like to convert it into an (semi) active closed loop system, to speed up the recovery (and as a bonus maybe be able a loop).

According to this graph:
https://encyclopedia.airliquide.com/butane#properties

Butane @3 bars should allready condens at ~302k, @2 bars it should condens at about 291 k, which is also quite near to the Clausius-Clayperon equiation result and this calculator:
https://www.omnicalculator.com/chemistry/boiling-point

I’m not looking to modify the system to a 300 psi system, but rather a hybrid system, keeping the collection vessel in a cold bath (salt/ice), and apply a pressure ~3 bars to the recovery vessel to speed up the recovery time to about <30 min.

I was thinking about using a small piston pump for this, any idea which one to use, or better use a diaphragm one, or what specs to look out for?

Alternativly i could imagine, to just connect an air compressor to the system, and pressurize the whole system.

Also i would like to add a CRC collum to the system, can i just pack silica/activated charcoal under the bud or do i really need to add an extra colum? Any experience on how it does on dewaxing, or do i really need to dewax with dry ice in the jacketed colum/winterisation?

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All those questions have answers on this forum. You might need A air compressor for the pump but some nitrogen might help you as well.

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My advice would be to just stay passive and look into nitrogen assist.

No need to keep the collection cold, you can have it warm and recover/inject simultaneously.

Chill your recovery vessel and condenser if you have enough dry ice. You can also get by with only using dry ice on an injection coil, and use another coil or shotgun condenser with dry ice for recovery. You’ll save a lot of dry ice if you’re only using it on coils, rather than trying to chill the whole solvent tank.

Sounds like a bomb waiting to happen. Using an air compressor for a recovery or Venturi pump, sure. Not to pressurize the whole system. Use N2.

No need for a separate column, but it would increase throughput and make things easier if you have multiple runs.

Depends on temp, soak time, and how your filtration is set up. If you’re not running with dry ice or a chiller, you’re going to pick up a considerable amount of fats. You’ll also need to use a lot more media to achieve the same color running at that warmer temp, and the product won’t be nearly as good (if at all) in the end.

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Any pictures of ur system

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Hi, yes here is a picture of the system:

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No need to keep the collection cold, you can have it warm and recover/inject simultaneously.

Chill your recovery vessel and condenser if you have enough dry ice. You can also get by with only using dry ice on an injection coil, and use another coil or shotgun condenser with dry ice for recovery. You’ll save a lot of dry ice if you’re only using it on coils, rather than trying to chill the whole solvent tank.

Yes, here we we’re talking about the same thing, i meant the recovery vessel, not the collection vessel.

ATM the recovery vessel, is also the condensator, but well shouldn’t be the problem to weld something up, or just use the jacketed extraction colum from the 2nd extraction set like a liebig condenser.

Sounds like a bomb waiting to happen. Using an air compressor for a recovery or Venturi pump, sure. Not to pressurize the whole system. Use N2.

Well i don’t think it will act like a bomb, due to the wrong ratio of fuel/CO2, but i fully understand your concerns. N2 is not at hand, but CO2 or Argon are at Hand, i would go with those.

No need for a separate column, but it would increase throughput and make things easier if you have multiple runs

Depends on temp, soak time, and how your filtration is set up. If you’re not running with dry ice or a chiller, you’re going to pick up a considerable amount of fats. You’ll also need to use a lot more media to achieve the same color running at that warmer temp, and the product won’t be nearly as good (if at all) in the end

Ok, thanks for that answer and calrification that my go thought was ok, i see your point with the temperature and ammount of dirt beeing collected. Propably I will just stay with winterizing and filtration using EtOH.

From what i understood now, the best option propably would be to start by adding a 2nd intake to the butane starting tank (marked red).(Does it need a downpipe ?).

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Process woud be connect it to the frozen (?) extraction column, put the recovery tank in a cold bath, evacuate the whole system, open the valves for the butane. Wait until the butane left the starting tank. Then add the pressurizing gas (n2/Ar/CO2) to the butane reservoir, pressirizing the whole system slighltly and forcing the
butane into the recovery system. One recovery is done, vent the system and frozen recovery tank from gas.

I will post pics of the assembled system later, so we talk about same thing.

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Hi, sry for not answering, but had a little tick bite, that gave me borelliosis, not to fun.

I‘ve modified the system like you guys suggested, have my 2nd Jacketed tube now on top of the reclaim vessel. Collection vessel not cooled.

When starting the collection, i pressurized the system to +2 bars using CO2.

Recovery time now is down to about 2 hours, heating the collection chamber to 36C.

Revovery rate is about 85%.

Since i‘ve no dry ice, i need to refine the cruse bho. For that i will dissolve in EtOH and CRC using Silica gel/activated carbon as a medium

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Ethanol as a solvent for decolorizing with adsorbents doesn’t perform nearly as well as alkanes do. Also, removing the ethanol, unless you have a rotovap, requires such high temperatures and long residence times due to its high boiling point that you’re going to degrade your end product and be forced to completely sacrifice your aromatics fraction.

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Hi,

ok good to know.

Then i propably try pentane next.

But a Rotovap is there.

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Honestly with either of those solvents you’ll likely need to discard your aromatics. You might be able to separate them from the solvent sufficiently through distillation though.

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So which solvent wiuld you recommend?

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Do you want your aromatics or are you only after the cannabinoids?

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Maybe defining your goals would help.

Sure, winterizing in ethanol will remove some of the stuff you didn’t mean to extract (fats/waxes).

Yes, you can also get some color improvement (in ethanol) using the right absorbents. See Eg: TheLostBiologist Bucket and Post Processing Tek for Golden Extract

…but you’re gonna loose many of the lighter volatiles when recovering/removing the ethanol.

Does that matter? Depends on where you are and what your plans are.

You won’t win any competitions with room temp BHO that has been winterized in ethanol, but 10+ years ago it was absolutely possible to extract at -30C, winterize, and achieve shatter that placed here in Oregon.

In your locale you might still be able to outshine anything else available.

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I want to make BHO that is the best quality possible, with what is available. Focus is not on the cannabinoids, rather sacrificing some to keep some Terps inside.

For reference standard BHO available here is open blasted and normally even not vacuum purged, then there also is a lot of ISO extracts, where you can be happy if they don’t fully taste of ISO, top shelf is Rosin, but washing doesn’t work with my favorite strains.

Also thanks for the link, i will read it, looks very promising.

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If you’ve got a pump, look into how @IlluminatedExtractor’s are cooling and heating their systems…

(Presumably you’ve noticed you can achieve 0C just by evaporating solvent at atmospheric)

You can absolutely get (some of) your solvent down to -40 by using a recovery pump to move (some of) it into another tank.

You’ll also generate heat. Which you will need to dump (or use productively) to make this work.

I’ve only ever used this trick to cool down my extraction columns (and generate pressure to move solvent around), so I don’t have data on what percent of your solvent you’d need to recover to achieve a 60C temp drop, but if you poke around on engineeringtoolbox.com you might be able to math your way there.

Were it my problem, I’d look at how much “heat” I’d need to pull to drop 10kg of solvent by 60C, then calculate how much solvent I’d need to evaporate to achieve that number.

Or just try it and see…

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Thank you, yes well -20 is easy with Salt/Ice further with other salts.

Got no pump for moving solvent, but vacuum pumps (Oil/Diaphragm) are there.

An other question would liquid nitrogen work, instead of dry ice? That i can actually get quite easy, since we always have it in use at work. We dump about 5L each friday that could be used

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This system is so small you won’t be able to achieve significant temp drops via evaporation before you’ve run out of solvent to evaporate.

-20 is still not cold enough to completely avoid fats during extraction, but if you don’t soak it will produce decent extract. If you aren’t going to add a second column for filtration add your media to the bottom of your column. You will need some filter felt(lookup tampon tek) and patience or a sintered disc you can put below your column to keep media out of your finished product.

At your temps I recommend clay at about 10% and silica at 5-10% by weight to material. This will allow you to preserve your aromatics.

My adsorbent company ships worldwide, but we don’t currently carry silica.

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Well i can machine myself an extra colum, thats not the problem, Tru-Clamp weld on flanges are readly available, got a lathe and TIG in the workshop too.

If that is the best way, i will just add a short column

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Then where does “active” come into your CLS?

Yep. Some linked here

Tell is you can even manage -40

I would agree that sans pump, evaporation won’t get you there… however, if you treat it as a refrigeration cycle, then it’s not about how much solvent you’ve got, or how big the system is. More how well you can optimize and/or minimize (unwanted) heat exchange.

I still like to see understand the math (@Zack_illuminated?), because I’m almost certain it’s not as trivial as

because, over the range of pressures and temps we’re talking about, the thermophysical “constants” aren’t…

[insert graphic I imagine @Zack_illuminated will post :shushing_face:]

The pilfered graphic below suggests pulling the evaporator down to ~ 0.175 bar (~25in.Hg) will get you into the -40C range.

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Which implies you could use a water cooled CMEPOL (ultimate vac 29+”) and make cold solvent by making hot water.

Maybe. Start here: Has Anyone Used Liquid Nitrogen to Chill columns, diamond miners, etc?

With appropriate metering, direct (controlled) cooling has certainly been explored by a number of folks. Others have just opened the valve and let her rip.

The leidenfrost effect will not work in your favor.

I’d looking into using a solvent + liq N2 cooling bath. I don’t see the right combo listed on the link given upthread, but it might exist…

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It’s not as straightforward as pressure in vs. pressure out, or just latent heat removal.

Atmospheric pressure (0 psig / 14.7 psia) corresponds to -44 °C for propane, but that doesn’t translate to 25" Hg (-12.3 psig / 2.4 psia / about -65c).

Traditionally, cooling capacity is limited by the mass of solvent boiled. My patented tech bypasses that assumption—it’s capable of generating more cooling capacity than the vaporized mass would normally permit. That shouldn’t be possible… but it is. There are subtle thermodynamic factors at play that shift the entire behavior of the system once you step outside traditional design constraints.

I’ve actually submitted this technology to NASA for a suborbital flight test as a cryogenic refrigeration system. Our 90-second proposal video had a 120% view rate and nearly a full hour of watch time—so it’s definitely generating serious attention.

As the system gets colder, it requires less power to keep cooling, while the same mass of refrigerant continues performing work at progressively lower temperatures.

Hope that helps—at least conceptually.

Heating (especially in this context) isn’t as trivial as it sounds either. The moment you need precise thermal control, stable phase boundaries, or synchronized energy exchange across working fluids, the whole system complexity ramps up fast. It’s not just “make hot water, get cold solvent” — it’s how, where, and under what constraints that defines whether the result is useful… or just warm water and lost time.

By traditional refrigeration math:

Heat to remove: 1020 kJ

Solvent to evaporate to achieve this: ~2.87 kg of propane

I’ve personally measured 32 kW of cooling at -40 °C by comparing inlet and outlet mass / temperature of extraction solvent over time.

The compressor in that setup was only moving 1.2 kW of vapor, yet the cooling output far exceeded what traditional models would predict.

So yeah—definitely not trivial.
It’s something new. Possibly even paradigm-shifting. :flexed_biceps:

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Well Ethyl Acetate is readly available, quite safe for humans and give -81 C. Looks like a good combo to me.

Also why no pump? Well the Idea was to convert the passive system into an active one. But seems that the biggest problem for this is, that my system is way to small.