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The Reflux Tower

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  • bn42ca@yahoo.ca
    Hi, I have a couple of questions regarding construction of a reflux column. I ve been reading the earlier posts in the group and there seems to be some
    Message 1 of 4 , Apr 5, 2001
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      Hi,

      I have a couple of questions regarding construction of a reflux
      column. I've been reading the earlier posts in the group and there
      seems to be some confusing information.

      One opinion holds that the cooling water supply to the condenser
      should pass through the column, but another is that there should be
      no additional cooling within the column. Yet another says to cool at
      the top, while others cool about half way up. There are also comments
      from others that talk of insulating the column, which is entirely the
      opposite principle.

      One of the websites claims that in a reflux tower every six inches is
      equivalent to one pass through a conventional pot still, so by
      extension, a three feet tower would equate to six passes through a
      pot still. If this is the case, then I can't see the purpose of
      further cooling within the tower. Would any or all like to comment on
      this to help clear my thoughts?

      On an allied topic, the packing used in the reflux tower varies from
      Raschig rings to stainless steel scourers to marbles etc. I had
      initially leaned towards using marbles because of their simplicity
      and ease of cleaning, but now I'm not so sure. The plans that I've
      looked at which use the scourers seem to indicate about twelve in the
      column. So if the column is three feet, then that's four to the foot,
      which even considering the surface area of the packing, still appears
      to allow quite a bit of volumetric flow-through. If I used marbles,
      then the packing would be much denser, so what would the overall
      effect be?

      I'll look forward to hearing the opinions of the more experienced
      users.

      Ian
    • Thomas Hart
      What a tangled web we weave... Let me see what I can do to cloud things further. In terms of packing material, the idea is to pack the material, whatever it
      Message 2 of 4 , Apr 5, 2001
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        What a tangled web we weave...

        Let me see what I can do to cloud things further.

        In terms of packing material, the idea is to pack the material, whatever it
        is, so that you have a great deal of surface area for your reflux. Don't
        think strictly in terms of number of pads, but rather how densely they fill
        your column.

        As for insulation, I only know that mine is insulated because at times it is
        very cold where I distill, while other times it is very hot and insulation
        has reduced the variation in my process that these external conditions
        contribute.

        I ran a cooling coil through the upper portion of my column (at about the 3
        foot mark on a four foot column) to give me another degree of control. It
        has a valve on it so I can regulate the flow of water through it. I have
        run the still with and without water in this loop and at various rates and
        love having it.

        I am actually preparing, on Kev's advice, to install a means by which to
        recirculate my distillate from my condenser back to the top of my reflux
        material. I am designing this and installing it so I once more have further
        control of my still, the amount of reflux and thus the quality of my
        product.

        Anyone who has thoughts, designs or ideas on fractionating towers please
        pass them on.

        Peace-
        the Stillpastor

        -----Original Message-----
        From: bn42ca@... [mailto:bn42ca@...]
        Sent: Thursday, April 05, 2001 11:34 AM
        To: new_distillers@yahoogroups.com
        Subject: [new_distillers] The Reflux Tower


        Hi,

        I have a couple of questions regarding construction of a reflux
        column. I've been reading the earlier posts in the group and there
        seems to be some confusing information.

        One opinion holds that the cooling water supply to the condenser
        should pass through the column, but another is that there should be
        no additional cooling within the column. Yet another says to cool at
        the top, while others cool about half way up. There are also comments
        from others that talk of insulating the column, which is entirely the
        opposite principle.

        One of the websites claims that in a reflux tower every six inches is
        equivalent to one pass through a conventional pot still, so by
        extension, a three feet tower would equate to six passes through a
        pot still. If this is the case, then I can't see the purpose of
        further cooling within the tower. Would any or all like to comment on
        this to help clear my thoughts?

        On an allied topic, the packing used in the reflux tower varies from
        Raschig rings to stainless steel scourers to marbles etc. I had
        initially leaned towards using marbles because of their simplicity
        and ease of cleaning, but now I'm not so sure. The plans that I've
        looked at which use the scourers seem to indicate about twelve in the
        column. So if the column is three feet, then that's four to the foot,
        which even considering the surface area of the packing, still appears
        to allow quite a bit of volumetric flow-through. If I used marbles,
        then the packing would be much denser, so what would the overall
        effect be?

        I'll look forward to hearing the opinions of the more experienced
        users.

        Ian




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      • Kev
        Ian, ... Everyone s still design is different, so the needs of the column are different. The basic idea of having a reflux column is to increase the number of
        Message 3 of 4 , Apr 5, 2001
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          Ian,

          > I have a couple of questions regarding construction of a reflux
          > column. I've been reading the earlier posts in the group and there
          > seems to be some confusing information.

          Everyone's still design is different, so the needs of the column are
          different. The basic idea of having a reflux column is to increase
          the number of times your alcohol is distilled. As you say, a reflux
          still is equivalent to putting the stuff through a pot still a number
          of times. The trick is to increase this number as much as you can to
          get close to the magic 98.something %.

          > One opinion holds that the cooling water supply to the condenser
          > should pass through the column, but another is that there should be
          > no additional cooling within the column.

          Cooling water does two jobs in a still. Sometimes these jobs are
          combined, sometimes they are separated. 1) it condenses the vapour in
          the condenser head so that you can collect it in liquid form. 2) it
          can be used at the top of the column to increase the reflux ratio –
          i.e. returning more product back down the column for re-distillation.

          > Yet another says to cool at
          >the top, while others cool about half way up.

          Do it at the top, definitely at the top! The only time it's
          worthwhile doing it lower down is if your heat input is too strong
          for the diameter of column you've got and you need to stop your
          column getting flooded. Look at Tony's website for details of
          column / heating combination recommendations.

          > There are also comments
          > from others that talk of insulating the column, which is entirely
          the
          > opposite principle.

          Yeah, I thought that as well! The idea, as Tom the Pastor says, is to
          make sure you're the one in control of the cooling, not the
          environment.

          > One of the websites claims that in a reflux tower every six inches
          is
          > equivalent to one pass through a conventional pot still, so by
          > extension, a three feet tower would equate to six passes through a
          > pot still. If this is the case, then I can't see the purpose of
          > further cooling within the tower. Would any or all like to comment
          on
          > this to help clear my thoughts?

          Tony's site (www.geocities.com/kiwi_distiller) also has details as to
          how many pot-runs you get per length of column. It also depends on
          the diameter, type of packing, heat, etc., etc., etc., but the basic
          principle is the same – more is better. Having said that, you do
          reach a point where more makes no difference. A 10 meter column isn't
          going to be worth the hassle of finding somewhere big enough to run
          the damn thing, for instance :-)

          > On an allied topic, the packing used in the reflux tower varies
          from
          > Raschig rings to stainless steel scourers to marbles etc. I had
          > initially leaned towards using marbles because of their simplicity
          > and ease of cleaning, but now I'm not so sure. The plans that I've
          > looked at which use the scourers seem to indicate about twelve in
          the
          > column. So if the column is three feet, then that's four to the
          foot,
          > which even considering the surface area of the packing, still
          appears
          > to allow quite a bit of volumetric flow-through. If I used marbles,
          > then the packing would be much denser, so what would the overall
          > effect be?

          Again, as Tom said it's the surface area you're trying to increase
          here. This gives the vapour something to condense on and flow back
          down the column for re-distillation. There's more techie stuff to it
          than this, but this is the basic idea. Scrubbers give you the best
          surface area and therefore more pot-still equivalents for the same
          length of column packed with anything else.

          As to how many to put in per foot, that depends on the size of your
          scrubbers! I've seen 18 per metre mentioned, but the ones I got hold
          of filled the column up after just 4. Pack as many in as you can, but
          make sure you can still breathe through the packed column afterwards,
          otherwise the vapour won't be able to pass through it any easier than
          your breath and you'll have great refluxing, but zero stuff coming
          out to collect! Watch out when you're packing them in there, too, as
          I cut my hands to ribbons on mine.

          OK, that's refluxing in a nutshell, then we move on to fractionating!
          This is basically the same thing, but very controlled. You have ALL
          the distillate at the top of the column flowing back down the column
          for re-distillation and eventually you get the various sub components
          of the brew stacked like planes over Heathrow airport, with the one
          with the lowest boiling point (methanol) at the top. Once the column
          has settled out (several hours, possibly) you start to draw off small
          amounts of the distillate to collect. Obviously, you dump the
          methanol, and you can tell when this has finished coming off by the
          thermometer at the top of your column. Check Tony's site again for
          the exact temps, but from memory the good stuff is at 78.something
          degrees C.

          I hope this helps.

          Kev.
        • bn42ca@yahoo.ca
          This does help me think things through a little clearer. Thanks to you and Tom the Pastor for you advice. If anyone else would like to relate details of their
          Message 4 of 4 , Apr 5, 2001
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            This does help me think things through a little clearer. Thanks to
            you and Tom the Pastor for you advice. If anyone else would like to
            relate details of their experiences an adventures in this area, I
            would welcome their e-mails directly.

            Ian

            -- In new_distillers@y..., "Kev" <hurne@y...> wrote:
            > Ian,
            >
            > > I have a couple of questions regarding construction of a reflux
            > > column. I've been reading the earlier posts in the group and
            there
            > > seems to be some confusing information.
            >
            > Everyone's still design is different, so the needs of the column
            are
            > different. The basic idea of having a reflux column is to increase
            > the number of times your alcohol is distilled. As you say, a reflux
            > still is equivalent to putting the stuff through a pot still a
            number
            > of times. The trick is to increase this number as much as you can
            to
            > get close to the magic 98.something %.
            >
            > > One opinion holds that the cooling water supply to the condenser
            > > should pass through the column, but another is that there should
            be
            > > no additional cooling within the column.
            >
            > Cooling water does two jobs in a still. Sometimes these jobs are
            > combined, sometimes they are separated. 1) it condenses the vapour
            in
            > the condenser head so that you can collect it in liquid form. 2) it
            > can be used at the top of the column to increase the reflux ratio –
            > i.e. returning more product back down the column for re-
            distillation.
            >
            > > Yet another says to cool at
            > >the top, while others cool about half way up.
            >
            > Do it at the top, definitely at the top! The only time it's
            > worthwhile doing it lower down is if your heat input is too strong
            > for the diameter of column you've got and you need to stop your
            > column getting flooded. Look at Tony's website for details of
            > column / heating combination recommendations.
            >
            > > There are also comments
            > > from others that talk of insulating the column, which is entirely
            > the
            > > opposite principle.
            >
            > Yeah, I thought that as well! The idea, as Tom the Pastor says, is
            to
            > make sure you're the one in control of the cooling, not the
            > environment.
            >
            > > One of the websites claims that in a reflux tower every six
            inches
            > is
            > > equivalent to one pass through a conventional pot still, so by
            > > extension, a three feet tower would equate to six passes through
            a
            > > pot still. If this is the case, then I can't see the purpose of
            > > further cooling within the tower. Would any or all like to
            comment
            > on
            > > this to help clear my thoughts?
            >
            > Tony's site (www.geocities.com/kiwi_distiller) also has details as
            to
            > how many pot-runs you get per length of column. It also depends on
            > the diameter, type of packing, heat, etc., etc., etc., but the
            basic
            > principle is the same – more is better. Having said that, you do
            > reach a point where more makes no difference. A 10 meter column
            isn't
            > going to be worth the hassle of finding somewhere big enough to run
            > the damn thing, for instance :-)
            >
            > > On an allied topic, the packing used in the reflux tower varies
            > from
            > > Raschig rings to stainless steel scourers to marbles etc. I had
            > > initially leaned towards using marbles because of their
            simplicity
            > > and ease of cleaning, but now I'm not so sure. The plans that
            I've
            > > looked at which use the scourers seem to indicate about twelve in
            > the
            > > column. So if the column is three feet, then that's four to the
            > foot,
            > > which even considering the surface area of the packing, still
            > appears
            > > to allow quite a bit of volumetric flow-through. If I used
            marbles,
            > > then the packing would be much denser, so what would the overall
            > > effect be?
            >
            > Again, as Tom said it's the surface area you're trying to increase
            > here. This gives the vapour something to condense on and flow back
            > down the column for re-distillation. There's more techie stuff to
            it
            > than this, but this is the basic idea. Scrubbers give you the best
            > surface area and therefore more pot-still equivalents for the same
            > length of column packed with anything else.
            >
            > As to how many to put in per foot, that depends on the size of your
            > scrubbers! I've seen 18 per metre mentioned, but the ones I got
            hold
            > of filled the column up after just 4. Pack as many in as you can,
            but
            > make sure you can still breathe through the packed column
            afterwards,
            > otherwise the vapour won't be able to pass through it any easier
            than
            > your breath and you'll have great refluxing, but zero stuff coming
            > out to collect! Watch out when you're packing them in there, too,
            as
            > I cut my hands to ribbons on mine.
            >
            > OK, that's refluxing in a nutshell, then we move on to
            fractionating!
            > This is basically the same thing, but very controlled. You have ALL
            > the distillate at the top of the column flowing back down the
            column
            > for re-distillation and eventually you get the various sub
            components
            > of the brew stacked like planes over Heathrow airport, with the one
            > with the lowest boiling point (methanol) at the top. Once the
            column
            > has settled out (several hours, possibly) you start to draw off
            small
            > amounts of the distillate to collect. Obviously, you dump the
            > methanol, and you can tell when this has finished coming off by the
            > thermometer at the top of your column. Check Tony's site again for
            > the exact temps, but from memory the good stuff is at 78.something
            > degrees C.
            >
            > I hope this helps.
            >
            > Kev.
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