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RE: [Distillers] Continuous Stills

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  • Ackland, Tony (CALBRIS)
    Forget about using continous stills and being able to take off the fractions in a hobby scale set-up. The rates just aren t there. Most of you are aware that
    Message 1 of 7 , Jul 26, 2005
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      Forget about using continous stills and being able to take off the fractions in a hobby scale set-up. The rates just aren't there. Most of you are aware that I've built a couple of these stills (see http://homedistiller.org/cont.htm ), and they work fine. Easy to make from an exisitng column, and once running, dont need fiddling/tuning during the course of the run.

      But they are slow. Slower than your normal run, because they are also having to do the "preheat" that you normally do first/seperately - eg if your normal run is 1hr preheat + 4 hr running, and you collect say at 20 mL/min (total of 4.8L), well now the continuous still will be the full 5 hours to run the same volume, but its coming through at (4/5)*20 == 16 mL/min.

      Then do the translation for any heads or whatever that you desire to take off at another level in the column. Say you were to collect 150-200mL of heads from that run. That is now being spread out over the full 5 hours. 200/(5*60) == 0.6 mL per minute. A very slow drip. But in that same minute, think of how much additional material has been going past that portion of the column. For a 1800W heat source, its about 140 mL/minute (1.8 g/s). So your piddly 0.6mL/min of heads is being diluted by 140 mL/min of other product there. Unless you have built up a sufficient volume of that "head" material to recirculate at that 140 mL/min through the upper portions of the column, it wont be pure heads there, but instead being diluted with good quality ethanol (so much for steady state!). You'd still need a second run to try and remove them.

      So either, you will need to go to a very tall column - one able to support a sufficient volume of heads circulating in its upper region (how long will it take you to accumulate & equilibriate it ??), or accept that they're being diluted away beyond recoginition. You can overcome these problems in a large commercial scale setup, but not on hobby volumes or timescales. Plan on running yours for weeks/months, not hours ?

      For a hobby, continuous stills are great for stripping large volumes of wash. But its impractical to use them for head removal.

      Tony
    • J W
      Hi Tony How would it go if the u tube in your drawing went down to below outlet of the boiler through shotgun condenser, heated with outlet of boiler back up
      Message 2 of 7 , Jul 26, 2005
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        Hi Tony
        How would it go if the u tube in your drawing went
        down to below outlet of the boiler through shotgun
        condenser, heated with outlet of boiler back up to
        column. This would pre heat the wash and help with
        seperation. You would insulate return pipe to still.
        Modified drawing at below link.
        http://tinyurl.com/7mmno
        All coments welcome

        JW

        <Tony.Ackland@...> wrote:

        > Forget about using continous stills and being able
        > to take off the fractions in a hobby scale set-up.
        > The rates just aren't there. Most of you are aware
        > that I've built a couple of these stills (see
        > http://homedistiller.org/cont.htm ), and they work
        > fine. Easy to make from an exisitng column, and
        > once running, dont need fiddling/tuning during the
        > course of the run.
        >
        > But they are slow. Slower than your normal run,
        > because they are also having to do the "preheat"
        > that you normally do first/seperately - eg if your
        > normal run is 1hr preheat + 4 hr running, and you
        > collect say at 20 mL/min (total of 4.8L), well now
        > the continuous still will be the full 5 hours to run
        > the same volume, but its coming through at (4/5)*20
        > == 16 mL/min.
        >
        > Then do the translation for any heads or whatever
        > that you desire to take off at another level in the
        > column. Say you were to collect 150-200mL of heads
        > from that run. That is now being spread out over
        > the full 5 hours. 200/(5*60) == 0.6 mL per minute.
        > A very slow drip. But in that same minute, think of
        > how much additional material has been going past
        > that portion of the column. For a 1800W heat
        > source, its about 140 mL/minute (1.8 g/s). So your
        > piddly 0.6mL/min of heads is being diluted by 140
        > mL/min of other product there. Unless you have
        > built up a sufficient volume of that "head" material
        > to recirculate at that 140 mL/min through the upper
        > portions of the column, it wont be pure heads there,
        > but instead being diluted with good quality ethanol
        > (so much for steady state!). You'd still need a
        > second run to try and remove them.
        >
        > So either, you will need to go to a very tall column
        > - one able to support a sufficient volume of heads
        > circulating in its upper region (how long will it
        > take you to accumulate & equilibriate it ??), or
        > accept that they're being diluted away beyond
        > recoginition. You can overcome these problems in a
        > large commercial scale setup, but not on hobby
        > volumes or timescales. Plan on running yours for
        > weeks/months, not hours ?
        >
        > For a hobby, continuous stills are great for
        > stripping large volumes of wash. But its
        > impractical to use them for head removal.
        >
        > Tony
        >
        >
        >
        >
        >
        > Distillers list archives :
        > http://archive.nnytech.net/
        > FAQ and other information at
        > http://homedistiller.org
        > Yahoo! Groups Links
        >
        >
        > Distillers-unsubscribe@yahoogroups.com
        >
        >
        >
        >
        >




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      • Tony Ackland
        ... JW - technically you re right - it would help. The preheating would take some of the heat load off, allowing more for rectifying & faster offtake. But
        Message 3 of 7 , Jul 27, 2005
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          --- In Distillers@yahoogroups.com, J W <go_stiller@y...> wrote:
          > Hi Tony
          > How would it go if the u tube in your drawing went
          > down to below outlet of the boiler through shotgun
          > condenser, heated with outlet of boiler back up to
          > column. This would pre heat the wash and help with
          > seperation. You would insulate return pipe to still.
          > Modified drawing at below link.
          > http://tinyurl.com/7mmno
          > All coments welcome
          >
          > JW

          JW - technically you're right - it would help. The preheating would
          take some of the heat load off, allowing more for rectifying &
          faster offtake. But its a bit more fiddlier / complicating. I had
          had a play with a similar idea, and intermediate versions too, but
          came back to KISS.

          From the photo of my setup
          (http://photos.groups.yahoo.com/group/distillers/vwp?.dir=/&.src=gr&.
          dnm=Continuous+still.jpg&.view=t&.done=http%
          3a//photos.groups.yahoo.com/group/distillers/lst%3f%26.dir=/%
          26.src=gr%26.view=t ) you can see that i run the overflow into a
          bucket underneath - it would be a matter of simply running a longer
          tube, down into that bucket of hot overflow, then back up to the
          feed point.

          I wasnt really that concerned with the extra run time, so have kept
          with the simpler set up.

          The point of the previous post was more that trying to take heads
          off seperately is impractical, if not imposssible in a short-run
          hobby setup of limited capacity.

          Tony.

          ps - the emails from "MSC E-Customer Support Team" - they had signed
          on as a new member recently, but were obviously bouncing/auto-
          replying all emails sent to them. I involked my old Moderator
          status to remove them from the membership, to avoid it continuing
          (why Harry couldnt find them on the list). Maybe I should have just
          put them to "moderated" ? Too late now, but they're welcome to
          rejoin.
        • J W
          Thanks Tony If I get time I will experement with your design. JW ... (http://photos.groups.yahoo.com/group/distillers/vwp?.dir=/&.src=gr&. ...
          Message 4 of 7 , Jul 27, 2005
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            Thanks Tony
            If I get time I will experement with your design.

            JW


            > JW - technically you're right - it would help. The
            > preheating would
            > take some of the heat load off, allowing more for
            > rectifying &
            > faster offtake. But its a bit more fiddlier /
            > complicating. I had
            > had a play with a similar idea, and intermediate
            > versions too, but
            > came back to KISS.
            >
            > From the photo of my setup
            >
            (http://photos.groups.yahoo.com/group/distillers/vwp?.dir=/&.src=gr&.
            > dnm=Continuous+still.jpg&.view=t&.done=http%
            >
            3a//photos.groups.yahoo.com/group/distillers/lst%3f%26.dir=/%
            > 26.src=gr%26.view=t ) you can see that i run the
            > overflow into a
            > bucket underneath - it would be a matter of simply
            > running a longer
            > tube, down into that bucket of hot overflow, then
            > back up to the
            > feed point.
            >
            > I wasnt really that concerned with the extra run
            > time, so have kept
            > with the simpler set up.
            >
            > The point of the previous post was more that trying
            > to take heads
            > off seperately is impractical, if not imposssible in
            > a short-run
            > hobby setup of limited capacity.
            >
            > Tony.




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          • go_stiller
            Hi Tony When you ran your continuos still, did you return any reflux or run flat out as striping still. Was just wondering in case the reflux dropped into
            Message 5 of 7 , Jul 28, 2005
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              Hi Tony
              When you ran your continuos still, did you return any reflux or run
              flat out as striping still. Was just wondering in case the reflux
              dropped into lower portion of column and mixed with wash inlet.
              Thanks for help

              JW
            • Ackland, Tony (CALBRIS)
              JW ... Very nice looking adaptor. Were you going to pack it with some scrubbers too ? No need for the space - might as well put that area to work. I ve got
              Message 6 of 7 , Aug 1, 2005
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                JW

                > Subject: RE: Continuous Stills
                >
                > Thanks Tony
                > I have built a feed as you had drawn in your diagram.
                > This will go on top of my column; it is in a sleeve,
                > which joins another column on top, I then put my
                > condenser on top of the second column. I was only
                > planing to strip with this setup, but will experiment
                > to see how pure a product I can get. I thought the top
                > column might flood if tried to get 96% as the total
                > length might use all the heat before reaching the
                > condenser. I have a thermometer in the boiler, the new
                > adaptor and the top of column so I should be able to
                > know what is happening. At the top of bottom column at
                > the hight of my liquid feed, what would you guess the
                > temp to be? I hope to pre-heat the wash with the waste
                > from the boiler.
                > Placed photos of adapter in photos continuos still,
                > link below.
                > http://tinyurl.com/dgqet
                > Thanks for all the help
                > JW

                Very nice looking adaptor. Were you going to pack it with some scrubbers too ? No need for the space - might as well put that area to work.

                I've got no idea what the temperature at the feed point "actually" is in mine, but if you were trying, you would want your feed to be coming in at just below its boiling point - eg around 91-92C for a 12% wash. That way its ready to go as soon as it enters, and doesnt form a "colder" zone in the column. (thats why i eventually never did the preheat - i wasnt going to get close to 91C, but i guess any bit does help)

                (eg look at the McCabe-Theil diagram / applet I have in http://homedistiller.org/refluxdesign.htm#multi - you want the alcohol to start "stepping" its way up in purity, and likewise, the water stepping its way down in purity as it heads towards the boiler from the moment it enters there - a colder feed would effectively move that diagram a little to the left ).

                You can basically draw this yourself just using the diagram at the bottom of http://homedistiller.org/theory.htm (the best bloody picture in the whole site - its all you need!) If you were to get your column into a steady state equilibrium, then measure its temperature up its height, you should be able to then draw on the column what the respective alcohol and vapour alcohol contents were. Any inlet up its height should then be matched to suit accordingly temperature & purity. I wasnt that precise with mine. I figured that it would need about 3-4HETP to strip out the water (see there are about 3-4 steps / zig-zags if you come in at 12-14% alcohol, and head towards 0%), so that was about 30-40 cm, and then i gave it a bit more to allow for feed coming up to temperature - thus the need for about 50-60cm for a stripping section. And i knew that my regular column hieght above would give the purity required out the top.

                The column, if well insulated, can't "use up" all the heat. The heat is effectively transported through the column by the vapour/liquid mix. It takes less energy to vapourise alcohol than water, so there is always a surplus of heat up the column, and further enrichment can continue to happen (up to 95-96%) provided you give it sufficient height& packing.

                Tony
              • J W
                Thanks again Tony Must make up a wash to test, will post results. Quite true I may as wall pack adaptor as well, as this will help disperse liquid evenly over
                Message 7 of 7 , Aug 1, 2005
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                  Thanks again Tony
                  Must make up a wash to test, will post results.
                  Quite true I may as wall pack adaptor as well, as this
                  will help disperse liquid evenly over packing from
                  internal holes of outlet.
                  JW




                  > Very nice looking adaptor. Were you going to pack
                  > it with some scrubbers too ? No need for the space
                  > - might as well put that area to work.
                  >
                  > I've got no idea what the temperature at the feed
                  > point "actually" is in mine, but if you were trying,
                  > you would want your feed to be coming in at just
                  > below its boiling point - eg around 91-92C for a 12%
                  > wash. That way its ready to go as soon as it
                  > enters, and doesnt form a "colder" zone in the
                  > column. (thats why i eventually never did the
                  > preheat - i wasnt going to get close to 91C, but i
                  > guess any bit does help)
                  >
                  > (eg look at the McCabe-Theil diagram / applet I have
                  > in http://homedistiller.org/refluxdesign.htm#multi -
                  > you want the alcohol to start "stepping" its way up
                  > in purity, and likewise, the water stepping its way
                  > down in purity as it heads towards the boiler from
                  > the moment it enters there - a colder feed would
                  > effectively move that diagram a little to the left
                  > ).
                  >
                  > You can basically draw this yourself just using the
                  > diagram at the bottom of
                  > http://homedistiller.org/theory.htm (the best
                  > bloody picture in the whole site - its all you
                  > need!) If you were to get your column into a steady
                  > state equilibrium, then measure its temperature up
                  > its height, you should be able to then draw on the
                  > column what the respective alcohol and vapour
                  > alcohol contents were. Any inlet up its height
                  > should then be matched to suit accordingly
                  > temperature & purity. I wasnt that precise with
                  > mine. I figured that it would need about 3-4HETP to
                  > strip out the water (see there are about 3-4 steps /
                  > zig-zags if you come in at 12-14% alcohol, and head
                  > towards 0%), so that was about 30-40 cm, and then i
                  > gave it a bit more to allow for feed coming up to
                  > temperature - thus the need for about 50-60cm for a
                  > stripping section. And i knew that my regular
                  > column hieght above would give the purity required
                  > out the top.
                  >
                  > The column, if well insulated, can't "use up" all
                  > the heat. The heat is effectively transported
                  > through the column by the vapour/liquid mix. It
                  > takes less energy to vapourise alcohol than water,
                  > so there is always a surplus of heat up the column,
                  > and further enrichment can continue to happen (up to
                  > 95-96%) provided you give it sufficient height&
                  > packing.
                  >
                  > Tony
                  >
                  >
                  >
                  >
                  >




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