Reflux questions...

[goinbroke2]

All I've ran is a potstill and I quite enjoy it. Now that mama is sucking back more than her fair share, now she wants me to make her some neutral for white russians/b-52's etc.
Told her I would have to build a reflux attachment for my still and I've never run a reflux before but..I guess I could if she wants it.
So here's the problem, I started looking at various types and the one that seems easiest to build would be Rad's. I was thinking of using 2" tube and building a 4' one with a furrel to clamp on my keg so I can swap from pot to reflux.

The problem; how does a reflux work?

I understand the reflux of liquid back into the pot etc, I mean what is the difference if I take off from a valve on the side, or take off from the top like a potstill? I guess I don't see how it's any different. Liquid turns to vapour and travels up, it either goes into the lyne arm (pot) or hits the cooling coils and falls back into the pot(reflux)

I'm thinking if I wrapped a cooling coil around my 2" verticle tube going to the lyne arm I could reflux it that way too right?
Right now my set up is a triclover clamp on 10-12" of 2" then changing to 1/2" and then on to the lyne arm. What if I made a potstill head with 4' of 2" then change to 1/2" and then onto the lyne arm.

Anybody understand or did I just confuse the heck out of everybody?

Ok, here is a pic of the still head. What if I made one 4' long and added cooling coils around it. Wouldn't that work?

Or should I just build a ...whatever Rad's is called?

Either way..for some reason the reflux thing doesn't make sense. Is it because so much gets refluxed as opposed to a potstill which takes everything off?

[Hawke]

Just returning the liquid to the pot is not refluxing.
For a reflux to work, there needs to be a tall column with spaced 'plates' to seperate the fractions.
The most common 'plates' for hobbiests is copper or SS mesh/scrubbers.
The refluxed liquid drops through this packing and reacts with the rising vapor.
Eventually, the fractions will stack themselves,by boiling point, with the lowest boiling point liquids at the top, and close to water at the bottom.
By removing product from just below the reflux condenser, you are taking the top fraction.

[big worm]

wposw makes a good pot stilled neutral...for me anyways.

[rad14701]

+1 on what Hawke said...

My still uses a two reducer reflux head that can be used as a combo still... If scaled up to larger copper I'd suggest removing the needle valve for pot still mode because even my 1.25" unit floods with the needle valve wide open if I push too much heat... I've got a batch of All Bran wash here I am hoping to get run soon with the needle valve removed for a pure strip run as opposed to refluxing foreshots and heads and then running wide open for the hearts strip... Yep, even with the column extension removed and a dozen marbles under the head I can get enough reflux to make decent cuts... Pot still hearts seem the same with or without the marbles...

[goinbroke2]

AHHH, that makes more sense. Kind of embarassing reading a million books on distilling and can quote dates things happened..but only know a potstill...
Like a continuous still then, the vapours coming up liquify at certain levels and the plate you take off at determines what your taking off.
So, how do you know where to place the take off point? I understand that stacking a bunch of scrubbers up there then taking off just below the lowest point you get the good stuff. But how was that determined? Or don't ask it just works?haha.

I guess I can't let the eyes glaze over when somebody mention a reflux still anymore.

More reading to do I guess.

One last thing, you still do cuts right?

[rad14701]

Yes, you still do cuts and they are more critical if you are shooting for neutral spirits... But the cuts can also be easier to detect because with a column a thermometer is your friend unless you are running primarily using a parrot and alcometer...

With a packed reflux column your separations go from bottom to top with the purest separation at the top, which also has the lowest temperature and highest purity... So, essentially, you have whatever the wash boiling temperature is at the bottom of the column and the maximum equalized refluxed purity temperature at the top of the packed column... That temperature might equate to 95% or 88%, depending on the efficiency of your reflux column and take off rate... Figure on 92% - 93% for most columns and you won't be disappointed...

And, of course, don't forget that you won't end up with nearly as much product from a reflux column as with a pot still because you have less water in the final product - but it will be at a higher purity...

[kiwistiller]

And the cuts are a lot wider. Mine are anyway, my VM just runs along at aezotrope for hours, then within about 30 minutes, hits a brick wall and virtually stops tails are so condensed I'm not recycling them. too skanky. Though I do have quite a tall column.

[goinbroke2]

Very good info, thanks. I'm thinking 4' but it could be almost any length because I have a two story garage. So, for example, I build a 8' column and coil up 20ft of tubing in the top, could I then run it really hard with a faster take off rate or will this take "hours" regardless. The reason I ask is I'm running propane,(lots of heat) but if it has to be slow regardless then maybe I'll do an electric conversion so I can plug it in and let it run while I'm doing other stuff in the garage.

Anybody have a preference on running a thermometer as opposed to a parrot and alcometer?




<<<keeps on reading about these fancy smancy "reflux" stills>>>

[kiwistiller]

You really need a good digital thermometer. Tails is indicated by a rise of about 0.2*C for me.

Height = purity (but has diminishing returns)
Diameter = Speed.

Because you're sending liquid back down the column, a reflux column will pretty much always be slower than a pot. they can also flood if you push them too hard. It's the flooding that limits the amount of heat you can throw at them, so a wider column, more room, faster output (simplistic view) .

[rad14701]

goinbroke2, the problem with height is that once you surpass a given height:diameter ratio you will experience diminishing return for your efforts... Much beyond 30:1 is overkill and will start degrading rather than improving performance...

[kiwistiller]

Yeah I'm at 30:1, and as I can get my hearts with a reflux ratio of about 1:1, I wouldn't bother with any more height. Starts to be a pain to put up and take down as well, not to mention reaching the valve and checking the thermo.

[HookLine]

Anybody have a preference on running a thermometer as opposed to a parrot and alcometer?

Definitely want a good thermometer on a reflux column, that reads in 0.1 C steps. Though use a alcometer too if you want.

For 2 & 3" column, any more than about 1500 mm of packing height and you start running into seriously diminishing returns, no matter how much ceiling space you got. Not to mention having to get up on a damn ladder to reach the valve.

[goinbroke2]

Holy crap! That's a fast response! LOL!
I'm going with an off set LM type I guess. 30:1 ratio, that would be 60" tall at 2" in diametre?
Ok, 5' column.

I'm thinking I'll try and find some 3" then. Reading some of the posts it was mentioned a certain still (store bought I think don't remember the name) had a 2400W element in it and it was just turned on. Adjustments were made by cooling flow. Now that i've typed that I'm thinking it must of been a VM type..nevermind, different direction then. In a 58L pot, what would be the power requirement to "leave on"? If I get an element it would be powered 220v from the welder plug or 110v from the wall socket but I don't want to get involved with electrical gadgets. I realise if the optimum for say 40L in a 58L pot would be 1000W for example, it would take a long time to heat up but the most I will do is build a two plug style set up so I can plug it in either 110 or 220v. So say 4000 on 110v would be 1000W I need to run and at 240v it would heat up quickly? Am I in the ball park?

[xx7777xx]

Goingbroke:

I'd suggest you build a VM column that fits your existing boiler. I have a keg boiler on propane with a VM and pot still head that I can switch back and forth with and am very happy with the results.

Some pics and design stuff:
http://s410.photobucket.com/albums/pp18 ... d%20Build/

VM's are super simple to run if you have a good digital thermometer. Basically close the valve, start your heat and let your column boil for a bit ensuring its not too hot that vapors are escaping out the top past your reflux coil. Let sit for a bit after you stabilize the boil (30-60 maybe depending on how patient you are) which allows your column to equalize. Once you are there, crack your valve a bit and collect your foreshots which happens pretty quick, and then you should start collecting at 77C (temperature for ethanol azeotrope) making your heads, hearts, and tails cut but taste and smell. You don't want to try and run a VM too fast or you'll upset the equilibrium in the column and you won't get pure product. As mentioned, the way to run faster is bigger column diameter. With my setup it doesn't take all that long to do a run, so if you already have a propane boiler setup I'd suggest building your column and start with using that.

x7

[Ayay]

My 2" column at 1m total height (36" packed) produces 95% consistently in LM mode. It's a bit slow at 0.8L/hr but me an wife can't drink it all and that's fast enough.

[goinbroke2]

I thought I replied to this already....am I losing it or what? LOL!

Thank you again all. 777 that is an awesome set up. I got some questions but I don't have time right now, maybe tonight.