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first trial results

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  • William Kloek
    I did my first distillation trial since 10 years. I am using a milk can (20 liters) with a 600 mm long, 40 mm diameter column complete packed with raschig
    Message 1 of 3 , Feb 2, 2004
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      I did my first distillation trial since 10 years. I am using a milk can
      (20 liters) with a 600 mm long, 40 mm diameter column complete packed
      with raschig rings (6 mm). To the colum a 80 cm double walled descending
      cooler (angle 60°C) is attached. The milk can is heated using gas. The
      maximum heat load is 800 W but during distillation it is run at about
      60% of the max.

      I distilled a 12.5 liter 18% alcohol mash (fermented sugar solution; 4kg
      sugar topped up to 12.5 liter). During distillation I noticed that it is
      not possible to have a stable distillation temperatur of 78°C but that
      the temperature stabilises at 83°C for some time and then gradually
      increases up to 91°C during the next 5 hours. Apparently my column is
      not long enough or the packing is not sufficient to have enough plates
      in order to reach higher purity. At the end I received roughly 2.3
      liters of 74% alcohol. The distillation rates were 600 ml/hr in the
      start and decreased down to 250 ml at the end.

      Some questions ( ihope I am not too rude):
      - How can I obtain higher alcohol percentages? Should I use a higher
      column or should I use a lower heat input (and even lower distillation
      rates)?
      - How important is the column diameter. What can I earn when I take a
      wider column
      - Will my distillation set-up give me any reflux or is it only minor
      with such a system?
      - It is also striked me that I could not keep the temperature constant.
      Does this mean that my system is not in equilibrium?

      Any comments are highly appreciated.

      I am considering to built a new column based on the single reducer
      outlined by bokakob. I am attracted by the idea that it has a
      multipurpose set-up. I was thinking of using this for both bulk
      distillation to prepare pure alcohol (using the 20 liter milk can) and
      for distillation of smaller quantities using a low volume pressure
      cooker (6 liter). I was wondering whether I can use the same diameter of
      the column for both applications or will I run into heat power or other
      problems.

      tia,
      William



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    • Ackland, Tony (CALNZAS)
      William, ... All three will work, to varying degrees. The easiest is to use a taller column. This will give large increases in purity, and allow you to run
      Message 2 of 3 , Feb 3, 2004
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        William,

        > Some questions ( ihope I am not too rude):
        > - How can I obtain higher alcohol percentages? Should I use a higher
        > column or should I use a lower heat input (and even lower distillation
        > rates)?

        All three will work, to varying degrees. The easiest is to use a taller column. This will give large increases in purity, and allow you to run the still quite fast. Using lower heat +/or increasing the amount of reflux will increase it too, but this slows things down and wont give such an increase in purity (except in maybe your case - going from little/none reflux to some will be a good first step). A packing with more surface area per volume will also benefit (eg scrubbers).

        See http://homedistiller.org/refluxdesign.htm#rr

        > - How important is the column diameter. What can I earn when I take a
        > wider column

        You need the diameter to suit the amount of heat you are putting in (and hence the amount of vapour that is generated). Provided the column is not flooding (choking because the liquid & vapour cant get past each other), then there is little change in purity due to diameter. Theory suggests that you will get optimum seperating happening if the column is on the verge of flooding, but I dont like that - to easy to get into trouble if the power surges a little, or reflux alters a touch, or say the packing starts to gunge up.

        > - Will my distillation set-up give me any reflux or is it only minor
        > with such a system?

        Sounds like it is very minor at present - just that which happens to cool on the column walls. If you can force more reflux to occur (eg insert a small cooling coil in the top of the column) you should see some good benefits.

        > - It is also striked me that I could not keep the temperature
        > constant.
        > Does this mean that my system is not in equilibrium?

        I'd say thats due to the lack of any decent reflux. Once you are determining the amount of reflux (via forced cooling) and controlling it to a steady rate, you can also consider insulating the column walls. This will help stabilise the column temperatures.

        Tony
      • William Kloek
        Tony, Thanks for your detailled answer. It gives me the impression that if I really want to achieve better results I have to invest in my column. Since I
        Message 3 of 3 , Feb 4, 2004
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          Tony,

          Thanks for your detailled answer. It gives me the impression that if I
          really want to achieve better results I have to invest in my column.
          Since I already have a milk can with a 1,6" connector I would like to
          build a new colum (single reducer - a la bokakob)) with the same
          diameter (also to make it multipurpose - I should also be used on a
          smaller pot) .
          Do you think that 1,6" is the right diameter in connection with the gas
          heater I use (max power 800W). I plan to make the reflux column about
          30" high: would that be sufficient in combination with a 12" condensor
          tube (with condensor coil) on top of the column.

          thanks
          William

          > Some questions ( ihope I am not too rude):
          > - How can I obtain higher alcohol percentages? Should I use a higher
          > column or should I use a lower heat input (and even lower distillation
          > rates)?

          > - Will my distillation set-up give me any reflux or is it only minor
          > with such a system?

          Sounds like it is very minor at present - just that which happens to
          cool on the column walls. If you can force more reflux to occur (eg
          insert a small cooling coil in the top of the column) you should see
          some good benefits.

          > - It is also striked me that I could not keep the temperature
          > constant.
          > Does this mean that my system is not in equilibrium?

          I'd say thats due to the lack of any decent reflux. Once you are
          determining the amount of reflux (via forced cooling) and controlling it
          to a steady rate, you can also consider insulating the column walls.
          This will help stabilise the column temperatures.

          Tony




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