Chilling the internal coil on my Solvent Tank

I’m running a small CLS with nitrogen push and a CRC. I have a 50# solvent tank with an internal coil and a vacuum jacket. I plumbed the internal coil for chilled water, using a 500 gph submersible pond pump, filled a big cooler with ice and water, and let it run. Monitoring the return water temp it got down to 33.7F. That’s as cold as I’d ever expected with just plain water and ice. As I thought about it I wondered. With this is running while I’m recovering from my coil, which’s in dry ice and acetone, the returning solvent is going to be below freezing. Two things are going to happen. The water will freeze or the solvent will warm up. Neither is good. If the water freezes it could burst the coil, cross-contaminating the butane with chiller water. If it warms the solvent, the thermodynamics of heat moving to the colder will be stalled.

Am I overthinking this?

What’s the proper way to best use this tank? I bought it from a friend that wasn’t using it. He was clueless. Now I feel the same.

Your analysis is correct. Freezing that coil in your solvent tank is potentially catastrophic. circulate a glycol mix, or an alcohol slurry.

Most folks put a chiller on that task. And aim in the -40C range or below.

I believe we have a report around here somewhere of those coils rupturing simply because the ends were left open to atmosphere. Water accumulated and froze…


A tiny wee bit of ln2 would work, as well. You’ll have to be careful about freezing the butane, but it’ll get the job done. Cost about the same, or less, as lc02/dry ice, overall.

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Typically we add inhibited propylene glycol to the water baths that need to get colder without freezing.

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Put just denatured alcohol in a bucket with your pump. Plumb an automotive power steering cooler in line before the tank coil and drop the power steering cooler into your injection coil slurry. You probably have everything you need accept the power steering cooler. Napa $30.


@Midnightoil for the win!!!

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Anything involving a $30 auto part dropped sounds freaking cool to me. NAPA Know-How. Let me see if I got this straight.

So, one of these:


In the cooler, with denatured alcohol/dry ice slurry with the submersible pond pump. Can the pond pump take that cold? It’s a Little Giant 500 gph Wuhan special. Seems super sketchy to plug that in and drop it in alcohol. I’m not scared. I’m just a little frightened. Won’t stop me if it works safely in the end.


If you do not have a good pump for alcohol just mix up some antifreeze / propylene glycol it will work for you and is not flammable .


with dry ice?

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You could use two coolers even one with the intercooler in acetone and dry ice for chilling the intercooler . Then a second one to hold the pump and antifreeze for circulating your antifreeze mix . Using this technique you get the best thermal transfer by using acetone and dry ice . As well as not have to pump flammable liquids because you are pumping the antifreeze Pg mixture


I like this a lot. The intercooler/cooler with dry ice and acetone can be in the extraction booth and all the electrical can be outside pushing antifreeze mix around. The intercooler could even go in a cooler with the injection coil I want to add. Clean with only two buckets to stoke with dry ice during runs.

I did not expect such an elegant solution, once again this forum and its members comes through with a win, keep us posted once you get this set up, should speed recovery along nicely


You know what’s worse that contaminating your tane with water?
Blasting tane through a pond pump…which is what would happen if the coil ruptured.
Now its a flame thrower.

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it IS…

However; you need fuel, air, AND an ignition source to achieve ignition.

you’re waaaay below the flash point of the solvent, the part(s) that might act as your ignition source are sequestered from oxygen…a) by the same seals that keep water out of the electrickery and b) by the fact that the electrickery is submerged…so while it probably qualifies as a Bad IdeaTM, nobody has reported the damn things catching fire…unlike some of the hydrocarbon recovery pumps we used to use…


I get it. I’ve seen shedtek that nearly made my head explode, but weren’t unsafe in actual operation. The fire triangle is pretty hard to complete with gases as long as there’s lots of ventilation. I run a 3000cfm explosion proof fan in an 1100 cubic foot space. It’d be pretty hard to hit the LEL for butane or acetone in this environment. Which was the whole idea of the extraction booth.


Apparently there are “seal less” mag drive pumps for pumping volatile liquids:


Did u build your booth @tdrommond? Can u show us?

This is the best thread yet, people aren’t being rude and egotistical, just good’ol fashion problem solving. Here’s my two sense, go buy a Costco deep freezer, mine bottoms out at -47 F. Rip the whole thing apart, turn it into either a cooler plate, or, plumb that into your tank chiller. Stick the heat exchanger into dry ice… Or another chest freezer full of acetone. Creating thermal mass, even if it’s cold, is super helpful for for reducing temperature fluctuation. And any decent HVAC guy can help you out, and you can plumb the thing into another whole room and just run insulated lines. Bonus to this idea is if you did have a catastrophic fail in the tank, the system is already set to handle high pressure and refrigerant. I’m fucking rambling, thanks for reading this brain vomit.

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Now I’m sitting here like… Is there a market for making chiller plates from chest freezer?:thinking::face_with_monocle::thinking:. Fucking green tax is so out of control, is there room for an industrious cash money bag boiiiiiiiiii?


If you wanna get real saucy, plumb the deep freezer refrigerant system directly to the coil.