Heating a pot still

[pixilated503]

Please forgive me if this has been mentioned but I couldn't find it in all my searching.

First off I am in the process of making a pot still with a 50L keg but thought I better sit tight and get some more info.

I'm a little confused as to how you are meant to heat it up to 78 degrees and distil off ethanol without it reaching boiling point (100 degrees) and getting unwanted alcohols. (I'm using a gas burner). My thinking was even with the burner on low, all that will do is heat it slower but it will still come to a boil. and may heat through the 78 degree to fast and leave good ethanol behind.

I guess my question is just, how do you keep it around 78 degrees with a gas burner instead of boiling it?



Thanks guys

[Jimmy1]

Mate you need to just let it boil. The vapours that come off first will be of those that evaporate at a cooler temp such as alcohols.
Its like having a 1 liter jug with 2 parts oil and 3 parts water and filling the jug up with water so it overflows and the oil will spill over first, similar to alc vapours in a boil.
I hope this makes sense cause it seems to in my head :lol:

[maheel]

dont worry it's ethanol that boils at 78'c not the water

you could heat it with a jet engine and it just boils at 78'c

the vapour temp of your pot still is likley to go above 78 thats just when it "starts"boil and to distill

as the alc come out the still the boiler liquid slowly increases to 100'c when it's only water left
it's a % of alc to water thing

in a pot still temps are not as controllable as a reflux and it is unlikely that 78'c will not be held at all for any length of time

when refluxing you want the vapour your taking off to be +-78 so you know it's "pure"
the actual boiler liquid may still be more than 78 (like 82?) depending on alc % in boiler

[maheel]

this is actually a very good question

a lot of newcomers often focus on temps and things that really they cannot control, i remember even trying to control the heat when i 1st started with a pot

it is often why they say a temp gauge is not needed on a pot still and just confuses you, i use one just for interest sakes

after a run or two it all makes sense :)

have a read about making cuts !!! thats way more important IMO

[MacStill]

It's Quite likely (depending on ABV of the wash) that you wont see any distillate coming out at all at 78c, it could start producing at about 84c or even higher for a low alcohol wash ;)

[maheel]

build it and run it

and post pics !!! :handgestures-thumbupleft:

[pixilated503]

ahhh that now clears up another couple of threads ive read :-D

So when I read about doing a spirit run and going "slow" that's just letting it heat up slower and taking more time with the cuts? as opposed to a stripping run where you can crank the heat and let the alcohol distil off with a bit less care?


Really appreciate the help and cant wait to get this still finished and running and will definitely post pics!! :P

[SBB]

This same question was posed resently and had some good replys.......will try to find it ....
Edit....Ok here it is......have a squizz at this and all will be revealed........hope it helps a little.http://aussiedistiller.com.au/viewtopic.php?f=17&t=867
This seems to be a pretty common thing that confuses newbies and takes a bit to get your head around.......maybe at some stage we need to compile a bit of info on the subject and make a sticky of it.

[not alan jones]

I guess my question is just, how do you keep it around 78 degrees with a gas burner instead of boiling it?

This is one of those :teasing-poke: moments, if you get your head around this, everything else becomes easier, or should do.

So let me try an explanation from a noob point of view (without the :whistle: )
No more talk of boiling, let's think about it turning from liquid to vapour :dance:
I will try not to use any numbers, as that might confuse things :think:

What is in your boiler/still will vapourise at a temperature which is totally dependant on the ratio of alcohol to water.
Alcohol turns to vapour at a lower temp than water, so depending on the ratio of your wash/mash you will get vapour at a specific temp.
Vapour temp at the top of a reflux column will be cooler than at the bottom of the column because it further away from the source of energy, this is how a reflux column works, but you will need to read a whole lot more to fully understand why/how it works :angry-banghead:
As your distillation progresses and you have removed a percentage of your alcohol, the ratio will change and the temp at which things vapourise will change.
Clear as mud so far....
The amount of heat applied to the bottom of a boiler will not affect the temp at which the contents turn to vapour, it will however change the amount of vapour produced.

UJSM has been good tonight so if this does not make sense..... I'll have a look in the morning.

[SBB]

I found this explaination over at HD...written by LTWS.....hope he doesnt mind me using it ......i think the last part in red explains it very nicely
Quote;
by LWTCS » Tue Jul 27, 2010 7:30 am
The boiling point of water is 212 and the boiling point of alcohol is 173.

A 12% (or 14 or 8 for that matter) wash will not boil at 212 or 173. It will boil at some point/temperature in between.
Once the liquid reaches its boiling point it will vaporize,,,,,,and exit the boiler. If the element is 250 degrees the boiling temp of the liquid will still be somewhere between 212 and 173. If the element is 350 degrees the boiling point of the liquid will still be somewhere between 212 and 173. All the while exiting the boiler.

No matter what the temp of the element is, the boiling point of the wash is always somewhere between 212 and 173

No such thing as 300 degree boiling water (as an example).

Am i saying this the right way?
LWTCS