New Still - Part 2
- The next step in my quest was to desing my system so
that it would operate as I wanted. In order to do
this, I decided to build a reflux unit on the top of
the column, loosely fashioned after an industrial heat
exchanger. I thought that with the vapour passing
through a unit where I could control the temperature,
this could do what I was after.
The core of the unit was made from 7 - 6" lengths of
1/2" copper pipe, mounted between end plates, see:
Core.jpg. The assembly was then soldered in place in a
length of 50mm pipe. An inlet was provided at the
lower end and an outlet at the top. These are supplied
by a 1/4" copper pipe tapped into the condenser water
supply. The condenser supply is fed at mains pressure
and the flow is regulated by a valve on the hot side
of the condenser. The inlet to the "reflux unit" is
tapped in on the pressure side of the valve and also
has a regulating valve in-line, while the outlet
connects to the drain side. This can be seen on the
In that way, I reasoned that no matter how little flow
I had through the condenser, I would always have
sufficient pressure to pass water through the reflux
unit. Also, because the supply would be warm, the
thermal gradient would not be too severe.
Well, my first attempt proved to be quite
enlightening! I had a batch of wine that I was not too
impressed with, so I ran it through the still. After
the keg came up to heat, the temperature at the top of
the column climbed rapidly. When I cracked open the
valve on the reflux unit, the temperature dropped like
a stone, but it took a minute or two for the water to
circulate through the unit entirely. I found it
difficult to regulate the column temperature precisely
and that a minimal increase in the water flow through
the reflux unit, had a dramatic effect on the column.
After some time and practice, I was able to stablize
the temperature at 80 deg and there it remained during
the run until I had accumulated 3.6l of spirit at 90%
abv. At this point, the temperature started to climb
and the output dropped off quite quickly. When the
temperature got to 84 deg, I stopped collecting and
shut the unit off. Oh!, forgot to mention I'm using a
propane stove for heat.
I must admit that I was hoping for better than 90%,
but it's not a bad start. Because of the lag in
temperature readings as the water flowed though the
unit, I decided that perhaps it was too efficient and
that I could have a more accurate control if the
reponse time was better and the water flow was not so
finicky. So, I took the reflux unit out and proceed to
shorten it to 4" long!
Now it's all back together again and waiting for my
next batch. I have a sugar solution fermenting right
now, so it will be a week or so before I can get to
I'd be interested in comments or suggestions.
Find, Connect, Date! http://personals.yahoo.ca
- I am trying to get the design clear in my mind. You have a 1m. length of
(2"diam) copper pipe mounted on top of the keg. And within the very top end of
that column you have a short multi-barrelled 'reflux unit'.
1) Is that section of the column completely empty?
2) Have you tried any packing in the 'reflux unit'?
Re: the 90%, I will defer to Tony Ackland on the mechanics and physics, but my
guess is that your rig is functioning as an inefficient reflux still. The 1m
empty pipe/riser acts as 1 reflux plate, and essentially does nothing, and the
'reflux unit' gives you a few more plates - but nothing on the order of 100s of
reflux plates in a scrubbie-filled column.
In fact, the more I look at the design the more I think that it functions as a
relatively efficient pot-still.
- Thats a great wee "firebox" condensor you've made there, and a nice
attachment to the keg.
Just one question for you - what are you using as packing in the column ?
It sounds as though you're getting a good range of reflux from the
condensor, but like you say, if it were working properly, you'd expect a
higher % from a tall, fully packed column. If using stainless steel
scrubbers for packing, you should the equivalent of a "redistillation" for
every 12cm height of packing. So a 1 m column will do the same as about 8
pot stills one after the other (and do 94%). At 90% its only doing about
3 or 4 redistillations. See http://homedistiller.org/refluxdesign.htm for
more details. If you're using marbles or broken glass as packing, they
only do a redistillation for every 33cm or so - which would only give you
about 3 over the 1m height, and hence about 88-90% purity.
With the way you've got the water set up, theres always going to be a small
amount of self correction needed. Eg if you increase the flowrate through
the reflux condensor, and return more of the vapour back down the column as
reflux, then less will be less hot vapour going to the final condensor.
Thus the water out of the final condensor wont be quite as warm as before,
so that the reflux condensor will then work even better with its cooler
water, and reflux even more ...and so on ... etc Its probably that you're
going to have to be very carefull / patient when "tuning" it, just taking
it a small bit at a time, and letting it settle down into a new balance
after each time you adjust the flowrates.
See if you can start the column off at total reflux (ie as much coolant
through the reflux condensor as possible), and then slowly reduce it, until
you first get the heads off at just a couple of drips per second. Once
you've finished collecting them, then just slowly reduce that coolant flow
until the alcohol is coming through at a reasonable flowrate at the purity
you're happy with. Its probably going to be easier to tune it that way -
from total reflux back down, rather than the other way - starting with no
reflux and inc it, because of that "feedback" you're getting via the
- --- In new_distillers@y..., John Vandermeulen <vandermeulen@n...>
> I am trying to get the design clear in my mind. You have a 1m.length of
> (2"diam) copper pipe mounted on top of the keg. And within thevery top end of
> that column you have a short multi-barrelled 'reflux unit'.Yes, but the reflux unit is additional to the 1m column
> 1) Is that section of the column completely empty?On the first test, it was packed with stainless steel scrubbers, to
function as a pot, I would need to remove then and run without any
The idea is of course, that I have a number of different options in
the way that it can be used, with very little effort.
From what I have seen, 90% is within the range of the commercial
units, but obviously not as high as can be achieved by a little more
attention to detail.
- --- In new_distillers@y..., Tony & Elle Ackland <Tony.Ackland@c...>
> Thats a great wee "firebox" condensor you've made there, and anice
> attachment to the keg.column ?
> Just one question for you - what are you using as packing in the
I had stainless scrubbers in for the first go -round
> With the way you've got the water set up, theres always going tobe a small
> amount of self correction needed. Eg if you increase the flowratethrough
> the reflux condensor, and return more of the vapour back down thecolumn as
> reflux, then less will be less hot vapour going to the finalcondensor.
> Thus the water out of the final condensor wont be quite as warmas before,
> so that the reflux condensor will then work even better with itscooler
> water, and reflux even more ...and so on ... etc Its probablythat you're
> going to have to be very carefull / patient when "tuning" it, justtaking
> it a small bit at a time, and letting it settle down into a newbalance
> after each time you adjust the flowrates.coolant
> See if you can start the column off at total reflux (ie as much
> through the reflux condensor as possible), and then slowly reduceit, until
> you first get the heads off at just a couple of drips per second.Once
> you've finished collecting them, then just slowly reduce thatcoolant flow
> until the alcohol is coming through at a reasonable flowrate atthe purity
> you're happy with. Its probably going to be easier to tune itthat way -
Yes, you're absolutely right and that's probably where I made my
error, I think that I was in too much of a hurry and I should have
started out with 15 or 20 min of total reflux before begining to run
off the spirit. That's my plan for the next batch. Thanks!