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automatic reflux ratio

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  • random9988
    I ve tested an idea I have had, how to control the reflux ratio automatic. Check files area - johan - self tuning head.png Explanation to the picture: A
    Message 1 of 1 , Jul 6, 2004
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      I've tested an idea I have had, how to control the reflux ratio
      automatic. Check files area -> johan -> self tuning head.png

      Explanation to the picture:
      A normal column with for instance an sr head, total packing height
      about a metre. (1) reflux runs down into a 6 mm tube that is
      soldered onto the column and is about 30 cm. Then down to a liquid
      lock (4) up in a tube 2 that ends a bit below the head. Product
      comes out in 3.
      The column is insulated including pipe 1. pipe 2 is uninsulated.

      The idea:
      From the start when you heat up the still and vapour condense onto
      the cold packing you get separation. even at the start it has high
      strength when it reach the top. that runs down in the tube 1.
      a bit down in the column the strength is lower and temperature is
      higher. If the distillate that comes down in 1 have higher strength
      the distillate will boil since it is heated through the column wall.
      When it does so the pressure in tube 1 is lower than tube 2, product
      stop. Reflux ratio increase and ethanol is accumulated at the top of
      the column. Temperature decrease in the column and the distillate
      stops to boil. Product is coming out. If it comes out to fast temp
      start to rise at the bottom again and product stop.

      The nice thing with this is that it reacts to the strength a bit
      down in the column so the top strength isn't changed. And it doesn't
      disturb the column too much.

      I tested it, in practice tube 1 is winded around the column in a
      spiral, it gets better contact that way. To my big surprise it
      actually worked at first test without any valve. Strength was 96 %

      But I used low strength mash then. It's a different story with high
      strength mash (or normal 14%) The reflux ratio to achieve 96% with
      good strength in the boiler is rather low, so the temperature
      difference inside the column isn't as pronounced then. The temp a
      bit down in the column isn't much higher than the top. Little heat
      pass through to the tube, also the flow in the tube is high and
      require a lot of heat to make it boil. So it reacts a little to
      late. When it finally reacts it does it wildly. In worst case
      pushing out all liquid, even that in 2.

      With a valve on 2 to limit the flow some the idea works. At the end
      it regulates itself to produce top strength even though the needle
      valve is set for rather big flow. (and stops automatic)

      I'm not pleased with it yet, I don't want any valves, the idea
      should work without any valve. Why? alright add a valve for heads so
      that can be removed slowly, but then open it full and let the still
      adjust by itself, making it run at high speed but with high quality,
      if the column is tall enough and the pipe 1 is low down, it should
      produce good quality. It has to do it foolproof, I hate almost
      working things =)

      Another approach to this would be to have a tube along the column
      that fills up with some distillate to begin with and then stays
      there. That'll give it plenty of time to heat up. When it boils it
      somehow prevent output. Another idea is to use air that heats up and
      expand and prevent output. Or capsulated 96% that builds up pressure
      and stops flow somehow easy.
      Or simply the same idea but with better heat transfer, smaller tube
      or longer, or pipes through the column or... well.. it cost money to
      test and I don't have the time.

      We'll see if I continue with this experiment further on.

      It has potential especially for fuel stills or vacuum stills or lazy
      distillers =)

      //Johan
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