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Which head to choose on my new still ?

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  • lalla23452000
    Hello! I m gonna build me a new still using a stainless steel 2 column, a bit higher than one meter. * But I wonder, which head should I choose for my still?
    Message 1 of 5 , Feb 3, 2004
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      Hello!

      I'm gonna build me a new still using a stainless steel 2" column, a
      bit higher than one meter.

      * But I wonder, which head should I choose for my still?
      The one under "photos" and "offset head still", is that a good one?
      (Nixon Stone I think)

      * How does it work? The vapour comes up the condenser coil and fall
      down to the valvue?

      * Won't some of the vapour leave from the top since its an open
      construction?

      * What's the point of the valvue in the buttom, is that to regulate
      the flow or something? What will changing in the water flow do than?

      * Is it not neccessary to put cooling pipes(s) through the column
      BEFORE the head while using this type?


      Looking forward for some good answers :-) Also very interessted in
      some measures and pictures from a very good still ;-)

      Thanx a lot... MVH Lalla
    • Ackland, Tony (CALNZAS)
      ... Yes, its very good. Well tested & proven. Simple yet effective. ... Yes ... No, not if the condenser is working. Providing the condenser has enough
      Message 2 of 5 , Feb 3, 2004
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        > * But I wonder, which head should I choose for my still?
        > The one under "photos" and "offset head still", is that a good one?
        > (Nixon Stone I think)

        Yes, its very good. Well tested & proven. Simple yet effective.

        > * How does it work? The vapour comes up the condenser coil and fall
        > down to the valvue?

        Yes

        > * Won't some of the vapour leave from the top since its an open
        > construction?

        No, not if the condenser is working. Providing the condenser has enough surface area, and cooling water through it, all the vapour will condense. Nothing will escape out the top. By keeping the top open, you are providing a safety vent should say your cooling water fail.

        > * What's the point of the valvue in the buttom, is that to regulate
        > the flow or something? What will changing in the water flow do than?

        It is to determine how much of the condensed liquid you return back to the column as reflux, vs that you withdraw & keep. Normally its about a 4 (return) to 1 (keep) ratio, more so when the alcohol in the boiler is getting down to a low %.

        With the offset head design, you have total control, being able to dial up anything from zero reflux (say you are doing a stripping run, or want to use it like a pot still), through to 100% reflux for when you initially equilibriate the column. Any any % reflux inbetween, thus letting you dial up any purity you want (provided the column is tall enough).

        You do not get the same effect by altering the cooling water flow. You need enough flow to condense all the vapour. Any more wont be a benefit, any less will be a huge problem as it means you have highly flammable vapour escaping.

        > * Is it not neccessary to put cooling pipes(s) through the column
        > BEFORE the head while using this type?

        NO !! Thats the purpose of the valve - to determine & meter how much reflux you are going to use. Those silly through pipes are bloody ineffective for doing that - they have such a limited range of reflux possible.

        Do not use cooling pipes through the column unless there is absolutely no other way you can generate the reflux. They are not a good way of doing that. And even if you do use them, only do so at the very top of the column, not part way down the column. See http://homedistiller.org/heatmass.htm for the explanation of how they stuff up the thermal equilibrium.

        Tony
      • lalla23452000
        But how can I keep the temperature below 80 degrees in the top without adjust on the water? I don t need to adjust on the power input? MVH Lalla ... one? ...
        Message 3 of 5 , Feb 3, 2004
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          But how can I keep the temperature below 80 degrees in the top
          without adjust on the water? I don't need to adjust on the power
          input?

          MVH Lalla

          --- In Distillers@yahoogroups.com, "Ackland, Tony (CALNZAS)"
          <Tony.Ackland@c...> wrote:
          > > * But I wonder, which head should I choose for my still?
          > > The one under "photos" and "offset head still", is that a good
          one?
          > > (Nixon Stone I think)
          >
          > Yes, its very good. Well tested & proven. Simple yet effective.
          >
          > > * How does it work? The vapour comes up the condenser coil and
          fall
          > > down to the valvue?
          >
          > Yes
          >
          > > * Won't some of the vapour leave from the top since its an open
          > > construction?
          >
          > No, not if the condenser is working. Providing the condenser has
          enough surface area, and cooling water through it, all the vapour
          will condense. Nothing will escape out the top. By keeping the top
          open, you are providing a safety vent should say your cooling water
          fail.
          >
          > > * What's the point of the valvue in the buttom, is that to
          regulate
          > > the flow or something? What will changing in the water flow do
          than?
          >
          > It is to determine how much of the condensed liquid you return
          back to the column as reflux, vs that you withdraw & keep. Normally
          its about a 4 (return) to 1 (keep) ratio, more so when the alcohol
          in the boiler is getting down to a low %.
          >
          > With the offset head design, you have total control, being able to
          dial up anything from zero reflux (say you are doing a stripping
          run, or want to use it like a pot still), through to 100% reflux for
          when you initially equilibriate the column. Any any % reflux
          inbetween, thus letting you dial up any purity you want (provided
          the column is tall enough).
          >
          > You do not get the same effect by altering the cooling water
          flow. You need enough flow to condense all the vapour. Any more
          wont be a benefit, any less will be a huge problem as it means you
          have highly flammable vapour escaping.
          >
          > > * Is it not neccessary to put cooling pipes(s) through the
          column
          > > BEFORE the head while using this type?
          >
          > NO !! Thats the purpose of the valve - to determine & meter how
          much reflux you are going to use. Those silly through pipes are
          bloody ineffective for doing that - they have such a limited range
          of reflux possible.
          >
          > Do not use cooling pipes through the column unless there is
          absolutely no other way you can generate the reflux. They are not a
          good way of doing that. And even if you do use them, only do so at
          the very top of the column, not part way down the column. See
          http://homedistiller.org/heatmass.htm for the explanation of how
          they stuff up the thermal equilibrium.
          >
          > Tony
        • jestah_nz
          ... top ... temps (i think) are more to do with the alc content in the vapor at the point in the still where your thermometer is.: So if you have a tallish
          Message 4 of 5 , Feb 3, 2004
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            --- In Distillers@yahoogroups.com, "lalla23452000"
            <satanz@s...> wrote:
            > But how can I keep the temperature below 80 degrees in the
            top
            > without adjust on the water? I don't need to adjust on the power
            > input?

            temps (i think) are more to do with the alc content in the vapor at
            the point in the still where your thermometer is.:

            So if you have a tallish reflux columb that is well insulated and
            the therm. is above the packing and you have removed the
            heads and hold it at 100% reflux then : alot of ethanol vapor will
            be sitting at the top around the therm. which would be reading
            about 78-78.8c. but if you ran it at NO reflux (pot still) the temp
            would rise as the amount of ethanol vapor around the therm.
            droped.

            now about heads .... Look into VM (vapor management) heads.
            Dont be fooled by the fancy pants name (as i was. i make a
            single reducer setup DAM GOOD design but it broke as im crap
            at soldering) i then made a VM setup and havnt looked back

            I like it because :

            Simple to use ( just turn a tap to open set reflux . done.)
            good CLEAN flava ...
            slows as heads come through
            and simple to make . ( one pipe suck onto the side of the columb
            to a gate valve to a elbow then to lebig.... NICE as it can be made
            with off shelf parts and only has one simi-tricky join)

            the only draw backs for me are:

            having to wait a few sec to see the change in reflux when you
            turn the gate valve (easy to get use to)
            having to take out top reflux coil and plug with wet rag... not a
            prob for most but im a midget (call me a little person and ill kick
            you in the shins !!!) and cant easy touch the top of my still. :)

            good luck in deciding ... *cough* *cough**VM**cough*

            Jestah

            BOB love ya stuff put it back as it is good and i wouldnt be
            sipping my own stuff if it wasnt for your plans
          • Ackland, Tony (CALNZAS)
            ... The temperature in the column is a RESULT of the alcohol vapour purity there. See http://homedistiller.org/theory.htm#strong for a graph of vapour
            Message 5 of 5 , Feb 4, 2004
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              > But how can I keep the temperature below 80 degrees in the top
              > without adjust on the water? I don't need to adjust on the power
              > input?

              The temperature in the column is a RESULT of the alcohol vapour purity there.
              See http://homedistiller.org/theory.htm#strong for a graph of vapour temperature vs purity.

              So to get the top of your column down to 80C, you need to have pure alcohol up there.

              NOT vice versa. Making the top of your column cold does not make the alcohol pure (if so, we would only need 2 inch tall columns with a very cold section at the top).

              So the question is "how do make the alcohol vapour pure" up there ?

              The answer is that it needs to have undergone a whole series of redistillations before it gets up there. See http://homedistiller.org/refluxdesign.htm for more details. To get those redistillations happening, you need to have some liquid coming down the column, to "clean" the uprising vapour. The vapour will take alcohol out of the falling liquid, and the liquid will take some of the water content out of the vapour. To get this working well, you need to spread the liquid out very very thinly. So you pass it down over a packing that has lots and lots of surface area (but doesnt take up much volume). For this to be optimum, it needs to be done at the dew point of the vapour (so insulate the column so not to get excessive heat loss, and dont stick cold through tubes @ 10C where the vapour wants to be at 83C). The more of the liquid you can provide (REFLUX) the more effective the process will be. The taller the height, also the more effective.

              So in a nut shell, to obtain good purity (as seen by a low head temperature), you need:
              * a tall column (at least 1m, preferably 1.2-1.5m),
              * with effective packing (stainless steel scrubbers or raschig rings),
              * at a stable temperature,
              * with sufficient reflux (ratio of 4:1 to 10:1)

              The key is the reflux. By changing the ratio of how much liquid gets returned to the column, you will have total control over the temperature that you see at the head of the column (provided the height & packing are sufficent).

              Thats the principle behind the Offset Head design. Tall column with good packing. Condense all the vapour into liquid. Control how much you want to draw off & collect - by default the remainder will be returned back down the column as reflux.

              If the valve is fully open you may be collecting say 150 mL/min depending on the amount of heat you supply. Normally you'd close that right down until you were only collecting say 20 mL/min. That means you are refluxing 130 mL/min (87% of the vapour being returned as reflux).

              Notice through all of this I've never touched the power input. I leave that on full, to keep every thing at the maximum rate. The only times you touch the power is (a) if you have over powered the still, and the diameter of the column is fundamentally too small, or say the condenser. (b) If you dont have control over the reflux, and have a fixed amount of liquid being returned - in that case you are altering the ratio by using less vapour - but thats less than ideal timewise.

              Tony
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