SD Vacuum Distillation

Moonshine

This discussion was created from comments split from: Thinking about buying a Dash 1.

BenStiller

Unfortunately, gravity is essential for a distillation column to achieve separation!

crozdog

@benstiller vacuum distillation is common.

its use lowers the energy input requirement as at lower pressure, liquids boil at lower temps. Industry uses it as it is concerned with cost efficiency.

but yeah gravity does play a part ;-)

Law_Of_Ohms

gravity and reality

Smaug

Surface tension in space rather than buoyancy or lack their of.

SDeurope

SD Vacuum Distillation -> The Next BIG Thing! :-bd

Law_Of_Ohms

oh great, vacuum still... Lloyd better go on holidays before we start any more projects!!! oops too late...

Lloyd

My head hurts when I think about vacuum distillation. I really just don't get it.
That screams opportunity for the entire community. If simple me don't get it then it stands to reason that the average distiller is also shying away from it too. Break it down into manageable pieces and together we could probably crack this egg and get, what?, 99%+ ABV alcohol? A gin basket that extracts flavor from the botanicals at a lower temperature? A slight increase in fuel efficiency? A faster run? More world peace?

LOO, doesn't the vac hose attach to the parrot? 8-} I just can't seem to get my mind around vac stillin. I saw something on AD about a year ago or so that made sense but didn't explore and now the whole concept is forgotten.

monty

Vacuum distillation? No thanks, I don't want Mrs. Monty near my stillstuff. :D

BenStiller

Gravity and vacuum are two separated concepts. Gravity is required for the liquid to flow down the column and the vapor to flow up the column, otherwise, everything would just sit in place and not much would happen. This is why distillation columns are set up vertically ;)

Vacuum, or rather reduced pressure distillation, is simply distillation occurring at a reduced pressure: something that changes (lowers) the boiling points of the liquid mixtures and can be beneficial because it also changes azeotropic conditions. It is often used to distill mixtures with high boiling points, which are temperature sensitive, or which exhibit problematic azeotropes.

One important thing with Vacuum Distillation : The whole apparatus, including the collection vessel, must be at the same pressure and vacuum must be drawn form the cold side, which means :

1. Using a parrot would be very complicated and impractical
2. Changing collection vessels will require some valves and some complexity.

The good news is that a SD vaccum still should be pretty straighforward and not even very expensive with the current available parts.

SD vacuum still:

Start with a Dash:

1. I would start by changing the bubble tees with straight sections as I would be worried of the mechanical resistance of the windows.
2. Remove everything after the shotgun condenser and install a 2" tee.
3. On the side of the tee, attached a 2" to barb connection.
4. Using a hose, connect the barb to a vacuum source (vacuum pump) It is possible that a water aspirator would be sufficient.
5. Place a (ball) ball valve bellow the tee (for changing vessels)
6. Connect a collection vessel bellow the valve (should be rigid, it could be a 4" or 6" TC pipe section with an end-cap.

It would look like the drawing in the attached file (sorry, I just drew a 2" column instead of a dash because I am lazy). *Added after Lloyd's comment"

I would put a pressure gauge at the top and temperature measurement at the top of the column but it will not be extremely indicative because they would be dependent on operation pressure.

This would have a significant learning curve. One would need to make sure that all parts can sustain vacuum. The pipes and fittings should be fine. I think the gaskets should resist too. I would also think that the keg would be sturdy enough not to implode :D

Lloyd

I hate posts like this without a very simple diagram. I get lost half way through with nothing to reference. I tried to tell you I'm already confused about vac distilling.
Fine, no parrot. Add a vacuum pump (very low vacuum I hope to keep the implosions to a minimum). Just feeling this gets complex quickly.
Help Punkin!!!!

punkin

Not me mate.

1. I'm not smart enough to try and complicate something so simple (that's why i still use my SD pot still)

2. I already carry that much stock it does my head in and still have to whole ranges every 6 months.

3. I think there safety concerns that mean we would have to rate all parts as pressure parts and we have no control over what people use as boilers or what other homemade parts they'll put in like glass cows etc.

Hope that's the help you were looking for? :))

Lloyd

Oh, I see now that @BenStiller did include a drawing. It didn't show up last night.
How do you make cuts? Everything just seem to go into one big collection vessel.

nvnovrts

gravity is constant. the higher the elevation/less air pressure the lower the boiling point of water. Gallo has HUGE (and I mean f;n HUGE) vacuum distillers. all the scientific lab supply places have vacuum pumps. You would just need to be able to attache a vacuum hose to the collection bottle and keep it at a constant bar. Same as running at a higher elevation will lower boiling points. The science is straight forward. I'll let lloyd work out the deets. .... #-o. Total science geek op here.

emptyglass

The splitting of fractions is where it gets complicated. Easy enough to understand, but the hardware poses problems. Manifolds, mutiple collection jars, valves all come into it. I have looked into it a little, but like Smaug said, the surface tension in a vacuum might put perforated plates out of the game, bubble caps might work, but a plain pot design is probably the best place to start. Any alteration to the vacuum pressure (or just plain vacuum) will alter the boil point.

Mountaineer

We vacuum distill our methanol off of our biodiesel at 10 gpm flow and at 45 gpm flow rate. What a lot of people don't think of is the fact that the less ethanol or in our case the less methanol that is in the fuel or water in our cases the higher the temp goes to get the methanol or ethanol off. For example our tower that we have is 24 feet and is 24 inches in diameter the whole system is under vacuum. You pull vacuum from the back side and have you're water ring vac pump elevated above the condenser and surge tank. We all know that methanol comes off at 148.5 degrees f but under vacuum it starts coming off at 95 deg. f. That is at 20 inches of mercury. We make 1 million gallons a month of biodiesel so we are pretty good at this. but to finish getting the methanol off the fuel to get the right flash point we are still under 20 inches of vac and 253deg. f to get it down. So everything has to be vac rated. Also because you're pulling ethanol it has many different alcohols involved and will pull them all off at different temps there for not giving you a very consistent product. heads and tails will be smeared and there won't very much that would be good. now if you built a very precise temp and vac system then I am quite sure that you could do you're very best at making a great product. Don't think that it would be very fun operating that. ours is all computer controlled and we have to have someone at the screen all day every 24 - 7. Anyway hope that you guys can kind of get an idea..

crozdog

I remember doing some reading on the russian forum (via google translate) about continuous distillation & vacuum systems.

A compressor out of a fridge can be used to make a vacuum pump. A mate has used one for years to vacuum bag carbon fibre/foam RC glider components.

Fluxed

Vacuum distillation (VD? lol) definitely has its advantages, but it also eliminates the possibility of fractionating your distillate unless you have some pretty sophisticated plumbing/valves on your output end.

It definitely wouldn't work with a parrot unless we engineered a system with site-glasses as well as the sophisticated plumbing etc.

Typically, VD (dear God) is used to rapidly distill one liquid in order to clean it, or to crudely separate two liquids, in a quick time with less heat input. It would be great for a stripping run though!

It's conceptually like those little glass bulbs that allow you to boil a liquid with just the heat of your hand...

Basically, you have your boiler/column/condenser/collection vessel all rigged together in an air-tight system. It would be like clamping a chamber on to the end of your shotgun where a parrot normally goes.

Then, you apply a vacuum to your system somewhere between the condenser and the collection vessel. Of course, you want to angle the condenser in a way that the vacuum won't suck out the liquid as it flows from the condenser.

These systems usually have the condenser at a 30ish degree angle as opposed to vertical for this reason.

The vac needs to be applied after the condenser because if it's on the reflux side it will just suck out your ethanol vapor.

So, there's a vacuum applied to your system. Because of this, the liquid in the boiler will boil quicker, with less heat required. It goes up through the column as a gas, condenses, and collects in your vessel just like normal.

The upside is very fast distillation.

The downside is that you can't really collect fractions, as you can probably imagine, unless you have some type of fancy rotating collection chamber. Also, I'm pretty sure it compacts your run so you get less resolution overall.

First Post!! Woo-Hoo!!

Fluxed

I somehow missed BenStiller's post, so I apologize for repeating a lot of what's in it.

But yeah...the more I think about it, the more I think that it would be great for stripping runs.

Also wanna stress that the shotgun would have to be much closer to horizontal than the usual vertical position so the vacuum doesn't accidentally suck out your product.

crozdog

i just read about Oxley Gin who are using vacuum distillation to make cold distilled gin....

Oxley Cold Distillation (PDF)

brantoken

I have been working on vacuum distilling for several years, it is not for the impatient. Contrary to popular belief, you can fraction. I have done it. In fact , there are several vacuum based solvent recovery systems ( fractionating column stills actually) out there. It does suffer from very high vapor speeds. I use a hybrid, so convention power is output 94% same system same packing ....etc won't go above 80% under vacuum . The largest problem I have had to date is cooling power, smaller the delta T coolant to ambient, the more fiddly it becomes. I don't have a chiller so I can only work it in the dead of winter. For the same recipe the flavors are quite different, so that is interesting. Also when it is dialed, it is very fast, haven't clocked it officially, too busy fiddling on the controls, it requires more attention.

I have ran it CM, and it certainly will work. Will be working a VM rig this winter. However is is more costly to make it work, I do agree with the guys here on that one. If you don't have some money to throw at it don't waste your time.

You have to want to tinker..... anybody want any more info PM me .

gixxerpilot750

Not trying to dig up an old post, but Aaron Schnell (screen name Schnell) made a number of posts explaining how he would set up a vacuum distillation apparatus over on AD before he passed away. If I recall correctly, he was an industrial chemist and developed a way to use solar powered vaccum stills as a side project. I'm not sure if I'm supposed to include links to AD or not, so mods please remove it if you need to.

Let's talk Vacuum Distillation

punkin

No problem with links to Artisan mate.

Tomer1

@Lloyd said: A gin basket that extracts flavor from the botanicals at a lower temperature? A slight increase in fuel efficiency?

There is a grappa producer from italy who runs a vacuum still, one of the first in the world. He distills muscat and other aromatic verietals at 15-20c. can you imagine the floral punch your getting from such a distilate. its so intense... I have yet to try it.

Tomer1

One of the problems, well not a problem per say but it makes things more heavy and expenssive is the boiler which needs to be made as a sphere with some supporting bars and fairly thick wall thickness to avoid collapse.

DemBones

Hello all,

I have have used a Vacuum pump in my Home Brew setup for many years.

The setup is that I hook a medical vacuum pump to the OUT of a Corny Keg and then hook a Hose to IN of the keg and a racking cane, This lets me Vacuum the beer off the trub and I don't have to worry about siphon or losing siphon.

you could to the same thing for stipping runs if you nixed the parrot and came straight off the still into a container and make the whole thing "air tight ish" as for doing this with sprite runs you would have to get creative with some valves and a manifold to do your cuts but thats more complicated.

the plus is that you can use much less energy for the stiping run becase by lowering the atmosphrice presure in the still you are lowering the boiling point of the liquides

its like a pressure cooker in reverse , under pressure of 15psi the cooker can make WATER 250F, its imposable to get water or things with lots of water in them above 212F under normal atmospheric pressure , but tack on 15psi and the boil point is up 38f

well if you draw a vacuum on the boiler it works the other way. here have some pics and a chart ;)

Me racking beer

Still on vac

Chart

DemBones

So... 100 points to the first person to crush there boiler in the vacuum!!!
Fun to think about but add a lot of complexity , and i am a KISS kinda guy for the primary operations functions of a device , sorry to dig up an old thread, i already replied before i saw it was old sometimes i forget it 2014....

Drunkas

I read down to where Lloyd was confused and asking punkin for help. Then punkin jumped in to Lloyd's rescue. But back to the thread. A vacuum still. Sounds like a pressure vessel to me. Something that would cost far more than the current SD gear dose. I would think every thing would have to come with some sort of compliance (big word) for safty. I cant see a dash unit being any good would be better of with some sort of hybrid. The less seals you have the better.
50 lt beer kegs are all ready a rated pressure vessel so as long as you dont mod them your sweet as to go.

Sunshine

we have tasted and compared several vacuum distilled spirits and those made of the same mash with normal distilling. Done so at the Acricultural Institute of Klosterneuburg by the scientist Prof. Gössinger (he is also a profi distiller) on a brand new Carl vacuum still. Sorry, but it was disappointing. You would think, that there was more flavor in a apricot brandy, since apricots are very delicate to distill, but there was not. They work on this topic quite a long time with scientific guidelines, the scientist is also a profi taster for spirits. They also think, that vacuum distilling is overrated. When the scientific paper is written and available, I will keep you updated.

punkin

You can't use less energy, energy doesn't work like that :))

If you add up the energy used to run the pump and heat the still it will be same joule thingos as just heating the still normally, at least that's how i understand energy to work.

The vacuum needs to have another purpose to be practical like Sunshine is saying. Striving to not destroy delicate compounds or some other purpose.

CothermanDistilling

I heard that some cutting edge craft distilleries are using rotovap