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Still Design

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  • Aaron Pelly
    I ve been thinking more seriously about building another column for my boiler. I have questions of course 8v) 1) The (necessarily) cooler temperature of the
    Message 1 of 3 , Sep 3, 2002
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      I've been thinking more seriously about building another column for my
      boiler. I have questions of course 8v)

      1) The (necessarily) cooler temperature of the condensate dripping onto the
      column packing in a N-S design must disrupt the reflux yes? Has anyone
      considered the implications of this? I do recall some brief mention
      somewhere (here or Tony's site I think) of not cooling the condensate too
      much. Should I care?

      2) Would it help to thermally insulate the condenser from the column?

      I imagine that vapour management counters this by allowing you to pull off a
      percentage of the distillate _before_ it is condensed. This allows the
      condenser to be separate from the column. Nevertheless there is still a
      separate cooling coil in the head that must be precisely controlled. On the
      face of it this _seems_ more complicated, but perhaps it gives more
      versatility. Comments and explanations appreciated.

      Decisions. Who needs them?

      Aaron.
    • Tony & Elle Ackland
      ... The volume of the reboiler is basically irrelevant - its the amount of heat that you use thats important, and making sure that you ve sized the column to
      Message 2 of 3 , Sep 3, 2002
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        > I wonder what size re-boiler would be needed for a typical reflux
        > tower type still for the second stage.

        The volume of the reboiler is basically irrelevant - its the amount of heat
        that you use thats important, and making sure that you've sized the column
        to suit it.

        About the only time the size of the reboilers (or thumpers in a non-heated
        setup) need considering is if you're not over-flowing / returning the
        liquid back to the main boiler. In that case, you need to consider the %
        of the streams in and out of it - eg if your main boiler is say 30L, and
        you start with a wash at 15%, then you will be generating around (30*.15)
        4.5L of pure alcohol. If this comes off at say 40%, then there will be
        (4.5/0.4) 11.25 L entering the first reboiler. If that reboiler is then
        making its vapour say at 65%, then only (4.5/0.65) 7L will leave that
        reboiler - ie it will gain around 4.2 L of liquid during the run. That
        could be a problem if its only sized to hold 2L. But you could use a small
        container there, if you had a submerged overflow that simply returned any
        excess back to the main boiler.

        Why do you want to go to reboilers, and not simply use thumpers ?

        Tony
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