30 Litre Airstill,- A.K.A.- A Silly Still......

[Easydrinker]

This has been a long,slow,train coming....
Let me start by saying that I have great admiration and respect for some of the designs,builds, and indeed the bling factor of some of the stills that I have seen on this site.
This one is nothing like those.........
Unveiled, the first incarnation of the current still of my dreams,- lots of copper to chop and change if and when the fancy takes me.
I built my first pot still (keg-based,worm condenser, water cooled), over 25 years ago,in an other age,and another place,and recently decided that I wanted to distill again.

A reason that I was drawn to the Smart Still was air cooling. And I continue to use one,with some happiness and great results.
It has It's place;but It's small capacity means I would not have the time, nor patience to run lower ABV washes through it, of say the grain type ones that interest me.

And so,because I could find little evidence of someone using a larger air still,that I could copy, (Believe me, I spent a lot of time trawling through inter-web history,-very few examples found), I decided to build this.
Space is an issue for me, from choice I have no spare bedroom/ cellar/attic/garage, nor shed, (See the pics. this beastie can only be run in my small shower area; and indeed was built to fit it).
I can also be single minded,and rise to a challenge,grip it like a terrier and not let go,unless it bites me on the nose,really hard.The fourth rebuild of this silly condenser almost had me go and spend some time constructing a Liebig,but I didn't.

The boiler is nothing special;- A modified commercial 30 litre stainless steel boiler,with a home built controller for it's 3KW elements.
The condenser is different;- 22.5 metres of double coiled 10mm worm (the monster started as 32 metres of triple coiled,[another story,another time]), cooled by a 35W domestic extractor fan,(about 5 cubic metres/minute),housed in a tube,cool air in the bottom,warmer air out of the top;, it must be more energy efficient than the examples I have seen of a fan blowing air from above , or from the side?

I found a figure (somewhere) stating that water is around 30 times better at cooling than air,but heat transfer co-efficients concerning vapours and air seem hard to quantify-at least to a non-mathematician such as myself, and seemed to produce varying cooling capabilities,and so I put away the calculator.
This condenser has a cooling area of just over 700 square cm, a "typical" 600mm x 15mm cored Liebig,such as AM's, has about 28 square cm ,- I simply paid extra and went large,here by a factor of 25.

If it was uncoiled ,the condenser coil drops about 1 in 18; with 10mm pipe I found any less gradient and the distillate would pool and splurge,OK for a strip,but not what I wanted for a spirit run.

A perceived problem posed by 2 individual coils is that of "smearing",unless both are condensing at the same speed;-and that appeared to be a challenging problem to try and solve.My intended, totally un-scientific approach was to be trial and error crimping of the top of the smaller coil until they both appeared to run at the same temperature,and dripped/ran at the same rate. When convinced that I had this right ,I would join the two outlets together,and be able to use a parrot; until then they would stay separate,and I would borrow the dog.......

I would allow a slightly larger fores cut,to be certain,as the shortest coil is only 80% the length of the longest .

But,without any crimping at all, vapour here is not taking the path of least resistance- or I finally got lucky with the coiling and gradients; as the shorter coil condenses a proportionately smaller volume of distillate,practically 80%, at the same speed as the larger one,albeit slightly warmer....and they start producing within seconds of each other.Maybe erroneously,I am now assuming vapour is entering both coils,evenly, at a constant speed,and that the distillate fractions will appear within seconds, from both outlets.I have not yet joined the outlets.

Anyway,at 1650 Watts,with inlet air at 22°C exhaust air 39°C,it knocks down all water/vinegar vapour,at 1,975ml/H, both outlets cool to the touch. and distillate at 23°C from the longer coil,25°C from the shorter.
At 1750 W,it condenses 2,115ml/H, air temps the same,distillate now at 25°C and 27°C,outlet pipes warm.
At 1850 Watts no steam,outlets hot;steam appears at 1900 Watts.

In it's running dress,the boiler is planned to be enclosed in 50mm "Kingspan Therma" foam, in an effort to not only insulate the boiler,but also keep excess heat away from the condenser.

It could have been made tidier , I tend to rush things.
Some parts could have been better thought about,but I went with some things I had, as I wanted proof of concept before more capital outlay.

It isn't at all pretty,but fulfills my agenda;
Fairly cheap and easy to build, (OK, the condenser was a bitch in it's first versions ! )
Modular;-easily broken down and stored - with two compression joints. (I do need to shower!)
The condenser bin/bucket sits nicely inside/on top of the boiler when not in use.
Air cooled.
A long term cashback bonus is that the boiler heat stays inside my domicile.
And it makes the good stuff.

I have only had a little time to play,but these are my findings so far;

The first (sacrificial) strip run showed that I had to turn the power down to 1250 watts at the start of the strip to keep the outlets cool.I was able to slowly increase power .Exhaust air was almost 20°C above inlet air all the way.
It stripped 24 litres of 14% wash in 2 1/2 hours (heat up time on full power was 45 minutes),yielding 7.5 litres @ 42%.About six times the speed or volume of the Smart Still,just what I was looking for.
For the spirit run of this strip I had to reduce the power to 1150 watts for the same reason, but kept it at that power.As this was not for drinking,I was happy to produce almost 3.5 litres of fire lighting fluid (above 80%),at almost 2.5 litres/hour,then the ABV dropped off; One litre at 40%, and 400ml @10%.
I then did another water only run,and deemed it ready to use.

First,and so far only real run; leaving the power at 1250 W.Inlet air 25°C,exhaust air 43°C.
Another strip of 14% x 24 litres.
45 minutes heat up at full power,then turned down to 1250W.
60 minutes later-2450 ml @ 70%
30 minutes later-1150 ml @60%
35 minutes later-1225 ml@50%
25 minutes later-800 ml @40%
At this point,in all honesty,I fell asleep,things were going so slowly,however;
150 minutes later,1500 ml @10%
I awoke to an over flowing container,but looking at the collected low wines,I only lost about 0.16 of a litre ,of pure ethanol,and would have expected to have stopped collection before this point.Annoying to miss taking smaller amounts and measuring ABV though.
However,just over 7 litres of pleasant smelling strip at 45%,mustn't grumble...

There will be some playing with power,as and when more washes are ready.And I look forward to combining strips for bigger spirit runs.Playtime just became more interesting.

This has taken longer than expected to come to fruition,and I am now working away from home for a few weeks and have no more time to play with it for a while.But at least the beastie is now built, and will stop taking so much of my spare time!

I have named this a Silly Still,because to some people it would seem so,with such a large air-cooled condenser,- but equally I can now fill in my profile stating that I own both a Smart Still and a Silly Still.
That amuses me.And I am doing this for fun.Simples.
Constructive criticism will be welcomed,laughter will be shrugged off,or joined in with.
Robert.


The condenser being stitched/supported with copper wire,-think of it as fins...

The only pic I have of it together and working,on a water run.

[chill]

I love the ingenuity! Bravo! I'll be interested to hear if there is any difference in quality/taste with the AirStill.

Chuck

[Capt-Cudellez]

I like the fact your running an air cooled still in the shower, the one place you are guaranteed a water supply. Bonkers

[Easydrinker]

I like the fact your running an air cooled still in the shower, the one place you are guaranteed a water supply. Bonkers

I like your point.
It might seem so,I didn't mention that I am on a tanked and pumped water supply.
The cost and effort of supplying water is not to be sneezed at.
Owning a small, ocean crossing boat,I have learned just how little water is needed to shower effectively.An awful lot less than a water cooled condenser. No,the still is NOT on the boat !
TBH,I would have tried this air-cooled route,even given a mains water supply,just because I could.
Not denying that I am bonkers.
Robert.

[Capt-Cudellez]

It wasn't meant as a criticism.

[Easydrinker]

I didn't take it as such.
And don't mind being referred to as bonkers anyway;to spend so much time coiling and re-coiling the condenser,I probably am.
Robert.

[Almanac]

I love the ingenuity....an Airstill on steroids

You could improve your cooling if you duct the air to the bottom of the cooling tower from an outdoor source. As your runs proceed the ambient air temp in the still space will increase reducing the air cooling efficiency. Just a thought

AM

[Easydrinker]

And a good one,it is a point I have considered,floor level air is going to stay pretty much the same due to domestic layout, - but in the depths of winter I could suck in air 20 - 25°C cooler,it would be interesting to see what the condenser could do with that...
Robert

[amaark]

Another easy and cheap way to increase the thermal efficiency of the cooler tubes would be to paint them matt black.

This will radiate the vapour heat more efficiently than any other colour.

Bonkers or not. It is said necessity drives enginuity

[Easydrinker]

Just a quick update.
Have now run this still for nine or ten strips and seven or eight spirit runs.
It works well.I now tend to strip at 1500 w,and spirit run at a slow 700W. It seems to be pretty consistent and predictable in product,rather like a Smart still,while producing something a little better tasting at higher volumes.
I haven't yet insulated it or joined the outlets from the condenser,still monitoring the two.
I built it with a tall column,with a partial intention of maximum reflux for a pot still,this it seems to do,the distillate seems to run at a high ABV for a pot.
A surprise has been the way it slows towards the end of a spirit run with a rapid drop off in ABV; - and tails appearing later than expected, at lower ABV's,typically around 40%.
All in all,very happy.
Robert.

[Icefever]

I now tend to strip at 1500 w,and spirit run at a slow 700W. It seems to be pretty consistent and predictable in product,rather like a Smart still,while producing something a little better tasting at higher volumes.
Robert.

Why is there a need to slow the still down?? what happens when you do this?

[Easydrinker]

The science of what happens,- I have no clue.
The result of my slower running is simply better tasting product.
And consistent results.
I KNOW the big distillers run hard and fast,some of them 24/7, 7/7, 52/52.
Thankfully they and I are worlds and wallets apart.
I have come to prefer mine to theirs,for the most part.
Robert.