Rotovap

grim

Did this for a gelato guy once too, he was trying to make a bourbon gelato, and he was reducing and dealcoholizing bourbon on the stove. I didn't love the stovetop product, the de-alc/de-water version was much better. Kept the heads fraction separate for this one, and I believe he used an eye-dropper to add it back in when they were freezing it back down (whatever that's called, not an ice cream guy).

jbierling

@grim said: Did a few bottles of bourbon for "dry January" for friends. Not necessarily zero alc, as you need to distill off a 'heads' fraction first, and add that back in after removing the bulk of the ethanol.

The time I tried this, the de-alc remainder was very cloudy. How did you turn that into something that looked remotely clear like bourbon? Were the heads enough to clear it up a little? Adding water to bring back to volume didn't help.

@grim said: You absolutely can not do this at atmospheric, the higher temperature will absolutely destroy numerous flavor compounds, you need to do this under deep vacuum at very low temperatures, and have a chiller that can support the temp ranges you need (we run around -10c or -20c depending on the time of year).

That's probably an argument for keeping bottles out of the sunlight too.

grim

We tried adding back water to reduce the concentration as well, but that killed stability and shelf life. I don't know that I really cared much about the appearance.

Found it just easier to adjust cocktail recipes and use the dilution from the ice instead. An old fashioned for example, really helped mask.

I don't think this is at all a path to a non-alcoholic whiskey. Could be part of the puzzle, but I doubt this is going to be economical enough to make sense.

Kind of related? We've played around a bit with quillaja as an emulsifier, it's used in high oil content clear beverages. The stuff has been out for a while, but seems to have exploded as an ingredient with the cannabis beverages - as they need to hold higher amounts of oils and terpenes. Hoped we could make a wicked concentrated gin, but it's not solubility in ethanol is a problem at anything more than minuscule quantities. It also foams to high heaven when shaken - which may be a plus or minus depending. This may be an answer to non-alc gin though, it absolutely works as a clear emulsifier in water-based. I would almost guarantee some non-alc gins are using this. I'll need to rotovap another bottle to see if it works to improve stability/quality of the non-alc bourbon, never thought of that. Again, this is basically screwing around, and screwing around for friends.

I don't think filtering is the option either, usually I'm pretty outspoken that filtration's impact on flavor tends to be smaller than many expect, but given the solubility issues here, filtration is going to suck out flavor.

grim

These guys did all the legwork to get approvals/gras/etc:

Q-NATURALE® high-efficiency emulsifier @ Ingredion

This wasn't the product we'd played around with. Looking at the page they talk about alcohol solubility, so curious if they've refined or extracted a more specific set of saponins from Quillaja that are more soluble.

grim

Much of the motivation here was being able to use vermouth or some other oddball mixers we can't produce ourselves, in our tasting room, which isn't permitted here.

Some may look at de-alc'ing Antica as heresy, but it 100% works.

jbierling

@grim said: I don't think filtering is the option either, usually I'm pretty outspoken that filtration's impact on flavor tends to be smaller than many expect, but given the solubility issues here, filtration is going to suck out flavor.

I did have the thought that the TCW Graver GFC Haze Pre-Filters might help since I've had good luck before with them for things that I really wanted to sell at 80 proof (instead of mid 90s).

@grim said: Much of the motivation here was being able to use vermouth or some other oddball mixers we can't produce ourselves, in our tasting room, which isn't permitted here.

Does NJ have some particular restrictions? We're a winery and distillery, I haven't lost any sleep mixing the two for a cocktail (vermouth).

jbierling

Looking at the rotovaps on eBay it is striking that almost all of them don't include glass -- which is the main reason I hate glass. Its not if it is going to break, its when.

Obviously glass is useful in a still for a lot of reasons, but it makes me wonder why more components aren't made out of vacuum rated stainless. Also, the typical small size of the openings into the evaporator and condenser glass is a PITA.

grim

Yeah, these things are not production devices, even the larger R-220 with the thicker glass is fragile.

Always wondered if you could reverse engineer the thin-film evaporators you see in industrial settings. Similar approach as a rotovap, but they don't rely on trying to spin glass.

DonalF

Not a rotovap question but a vacuum still question. Does anyone know if the dragonstill pots (specifically the 380 L pot) can work under negative pressures (i.e. under vacuum) and if so, how low can the vacuum go before there's a risk of impolsion? Any idea what thickness of the 304 stainless steel in the wall of the vessel is?

jbierling

@DonalF said: Not a rotovap question but a vacuum still question. Does anyone know if the dragonstill pots (specifically the 380 L pot) can work under negative pressures (i.e. under vacuum) and if so, how low can the vacuum go before there's a risk of impolsion? Any idea what thickness of the 304 stainless steel in the wall of the vessel is?

I'm sure @Smaug will answer, but the answer is likely to never run them under any sort of vacuum.

Smaug

The kettles are rated for 15 psi.

EDIT: 15 psi positive pressure. I have no idea if there is a negative pressure rating. Our factory does not test for negative pressure.

grim

The minute you pull vacuum on a vessel in a commercial setting, you enter the same territory as running a high pressure vessel (in the US anyway, though would imagine similar in Europe). This means your vacuum vessels are going to need to carry a certification (ASME in the US), a nameplate with design limits, and usually annual testing that your local government, and probably insurance company, will want. Generally if a tank is going to be under partial vacuum, it's prudent to design it to operate under Full Vacuum (usually indicated as FV on the nameplate), to avoid catastrophic damage if full vacuum is accidentally pulled, which is usually pretty easy.

Just because a tank can support # psi pressure, does not mean it can support the same differential as vacuum. There is no rule that works to convert a pressure rating to a vacuum rating.

Good example is a soda can, which is designed to hold anywhere from 90-120 psi pressure, but pull even a small vacuum and it fails catastrophically.

Might a tank that isn't rated work once or twice? Sure, maybe. 50 times? Maybe, maybe not.

Cue obligatory vacuum catastrophe video:

https://www.youtube.com/watch?v=Zz95_VvTxZM

grim

The vacuum rating would also need to apply to the collection vessel, and any associated piping.

Though the piping is probably the least worrisome part of this.

Column diameters do need to be upsized for vacuum use, as the vapor speeds are far higher, and flooding becomes a major issue.

Realistically, you'd probably need a 12" or 18" column on a 380l tank to keep vapor speed in check. Or settle with pot-still only.

DonalF

Thanks for your help folks. Much appreciated.

jbierling

Seeing as that the unicorn stainless rotovap still doesn't exist I might need to settle.

There are some large rotovap systems out there, but maintaining precise control over the distillation concerns me. Take this 50L system for instance.

How proprietary is the Buchi stuff? Could you use the v8XX vacuum controller and v7X0 pump to run this? @Grim, it looks like you use other brand pump & controller to control your Buchi, but what about the other way around?

jbierling

@CothermanDistilling, you have the fancy Buchi stuff. How easy is it to use with a generic vacuum still? I'm trying to make sense of all the connections and wires on the v700/V850. Does the controller work just connected to the pump? I suppose with the programming on the 855, it needs a temp sensor too. How does that hook up? Are you using a cold trap before the pump to protect it?

jbierling

I did a thing today. Fun doing something new for a change.

My little tiny vacuum pump gets to .5 mbar so that needs an upgrade. The 20L system takes a while to even get to that.

Now to move this into a closet so no one drops anything on it.

grim

Man, someone was dumping two buchi 215/855 full setups on FB Marketplace for $300. Must have been a scrapper clearing out a building. I missed them by 15 minutes. They had zero idea what they were, what they were worth, they didn't care.

jbierling

@CothermanDistilling said: It just seems the vacuum loves sucking out neutral... water, not so much....

I'm finding this out first hand. Water is difficult.

Well, think one problem is that my free very old Buchi B171 has real trouble getting below 90 mbar. And I have two other analog gauges both of which read less (and different) of a vacuum, so maybe it might be as high as 125. Reminds me of thermometers, where if you have three of them, you have three different temps.

Any insight on how low to go to really get water distilling with a bath <130F? Vapor temps are around 115F. My water is cold (51F) right now, but I'm guessing glycol is going to be needed at some point too? I have three condensers so I might plumb the top one before the vacuum takeoff (and maybe the middle) with glycol.

How much of a vacuum can you realistically pull with your pumps?

grim

On the stainless rotovap setup.

Keep in mind, you don’t need to “roto”.

Rotation requires fancy seals.

You could just as easily rock back and forth and get the same effect. The goal is to get a thin film forming on the wall, which evaporates faster than just boiling. I could imagine a 6x48” that teeter totters work very well.

Or, there has been a lot of work on ultrasound assisted evaporation. Bolting a sonicator to the wall of the boiler vessel would probably work well too.

On the Buchi stuff, you’d need to get the controller pin outs and build an adapter cable. The fancier 855 is going to be more difficult, as it connects back to the rotovap controller in addition to the vac pump.

Try pulling a vacuum without rotation, see how low you can go with the rotation off and empty. This can sometimes show if your seals are shot. Not being able to pull a low vac is a leak issue, or a bad vac pump.

grim

My third-party vacuum controller was easy because I was using a third-party pump. The accuracy and function is identical. Sure, I don’t get the autodist capabilities, but getting there is pricy. From the pump, the controller, the glass, and the incredibly expensive temperature probe (that I’ve never ever seen on eBay).

jbierling

@grim said: On the stainless rotovap setup. You could just as easily rock back and forth and get the same effect. The goal is to get a thin film forming on the wall, which evaporates faster than just boiling. I could imagine a 6x48” that teeter totters work very well.

I am gaining an appreciation for the glass of the boiling vessel allowing you see what's going on. Boiling "over" in a vacuum can happen almost in the blink of an eye and the glass allows you to see that. Probably 100x faster than an atmospheric distillation. I just want transparent stainless.

Or, there has been a lot of work on ultrasound assisted evaporation. Bolting a sonicator to the wall of the boiler vessel would probably work well too.

Sounds complicated ;)

On the Buchi stuff, you’d need to get the controller pin outs and build an adapter cable. The fancier 855 is going to be more difficult, as it connects back to the rotovap controller in addition to the vac pump.

I think I've given up on that.

Try pulling a vacuum without rotation, see how low you can go with the rotation off and empty. This can sometimes show if your seals are shot. Not being able to pull a low vac is a leak issue, or a bad vac pump.

Or in this case, leaking through the pump. I rigged up a valve that opens when the pump turns on to stop it leaking when it's not running which helped a lot. Still leaks maybe a mbar every 10 seconds, which is acceptable I think for a 20L system, but 80 mbar is probably the lowest it will go running full time with this pump. The diaphragms are probably just too old/stiff/worn.

My third-party vacuum controller was easy because I was using a third-party pump. The accuracy and function is identical. Sure, I don’t get the autodist capabilities, but getting there is pricy. From the pump, the controller, the glass, and the incredibly expensive temperature probe (that I’ve never ever seen on eBay).

I think you're using a three stage/chamber diaphragm pump? How low is it able to pull? Is <80 useful? I'm trying to decide whether to look at getting something else... I can probably wire up my pump's controller to start another pump too.

jbierling

Correction (not that it really matters, but I actually measured it), I'm leaking 1 mbar every 20 seconds.

jbierling

Have I mentioned I hate glass?

I'm playing around with replacing/supplementing my glass boiling flask with stainless. On my rotovap system, a 3" triclamp flange fits pretty tight and seals, so the world is my oyster connecting stuff to that.

The problem is that there are almost no ratings I can find about triclamp fittings holding up to vacuum. You can find a lot of cheap stainless vacuum degassing chambers (even one big enough for a 5 gallon bucket for $90!) so it seems this should work fine, but it's impossible to find one with a proper locking triclamp lid. So if you try to build something similar out of triclamp fittings, what is the max practical size before things get sketchy?

Falling film evaporators seem to use a lot of standard triclamp type fittings, but I assume at some size, you would run into problems.

3" to 8" bowl reducer connected to a 8"x8" spool section and then a cap. That's a pretty bombproof boiling flask isn't it?

What about inline sight glasses? Yes, I hate glass, but these things are pretty tough compared to standard lab glass. But again, I don't see any that say they're rated for vacuum.

punkin

I'd be looking at the pharmaceutical applications. Pharmaceutical, dairy and brewery share our triclamp system.

Smaug

I can't imagine there would be any cause for concern when putting ss tri clamp assemblies under vaccum for your purposes?

The Wall thickness on an inline site glass chimney glass is like 8 mm thick on average. And its round.

jbierling

I didn't think so either, but didn't want to miss something.

I wonder whether there is there any size/type of standard triclamp fitting that would collapse under high vacuum.

I did find a reference to some standard sight glasses regarding gaskets leaking, I imagine perhaps a gasket could get sucked in a bit if it wasn't supported from the inside.

I just want to avoid doing an OceanGate impression.

richard

It has very little or none to do with a tri-clamp fitting but more about the sphere volume and its wall thickness

Smaug

Tri-Clamp Fittings Burst Pressure and Temperature Ratings @ Sanitary Fittings

jbierling

That led me to Theoretical Bursting & Collapsing Pressures For Pipe Stainless Steel (ASTM-A-312) @ Tubeweb and ASTM A312 Stainless Steel Pipes - Bursting and Collapsing Pressures @ The Engineering ToolBox.

Too bad that stops at 6" and at 6" the collapse pressure is nose-diving. Seems like 8" spool might be iffy?

Also, end to end collapse should probably be considered at some point too.

Another: ASTM A213 Tubing Pressure Rating @ Guanyu Tube