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New Still - Part 2

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    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
    Message 1 of 5 , May 31, 2002
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      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
      Jpgs.

      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
      it.

      I'd be interested in comments or suggestions.

      ______________________________________________________________________
      Find, Connect, Date! http://personals.yahoo.ca
    • John Vandermeulen
      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
      Message 2 of 5 , Jun 1, 2002
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        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.
        JHV
      • Tony & Elle Ackland
        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
        Message 3 of 5 , Jun 1, 2002
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          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
          coolant temperature.

          Tony
          http://homedistiller.org
        • bn42ca
          ... length of ... very top end of ... Yes, but the reflux unit is additional to the 1m column ... On the first test, it was packed with stainless steel
          Message 4 of 5 , Jun 1, 2002
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            --- In new_distillers@y..., John Vandermeulen <vandermeulen@n...>
            wrote:
            > 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'.

            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
            reflux.

            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.
          • bn42ca
            ... nice ... column ? I had stainless scrubbers in for the first go -round ... be a small ... through ... column as ... condensor. ... as before, ... cooler
            Message 5 of 5 , Jun 1, 2002
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              --- In new_distillers@y..., Tony & Elle Ackland <Tony.Ackland@c...>
              wrote:
              > 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 ?

              I had stainless scrubbers in for the first go -round

              > 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 -

              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!
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