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Re: ⚗ Distillation Controller

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  • tgfoitwoods
    Tom, responses inline, in blue. Zymurgy Bob, a simple potstiller Making Fine Spirits ...
    Message 1 of 16 , Jan 12, 2013
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      Tom, responses inline, in blue.

      Zymurgy Bob, a simple potstiller Making Fine Spirits

      --- In Distillers@yahoogroups.com, "tyto_negro" wrote:
      >
      > Bob,
      >
      > Excuses accepted ;-)
      Thank you.
      >
      > I'm not contradicting you theoretical explanation of things, but:
      >
      > 1) a traditional alambique/pot still is a far-from-perfect thing. And that is good, we want a tasteful drink not technical C2H5OH in our glass. (People interested in that would go for more sophisticated reflux stills)
      I could not agree more. It's the "impurities" that make a fine liquor wonderful. That's why I also am a hardcore potstiller.
      >
      > 2) We have non perfect wine, that is, it is *not* a simple binary mixture. I'm making mainly natural fruit brandies.
      I agree again, and I make a lot of fruit brandies. My point using the curve for a binary mixture is that while the principle would be the same, creating all the curves for all possible concentrations of all possible compounds in the wash, would mean drawing those curves in n-space, which would be hugely difficult to display or read. It would also not change the fact that for each possible mix of components there is still one unique curve that relates boiling point to the progressive change in concentrations during the still run. Essentially one combination of concentrations, one boiling point.
      >
      > So, that makes a far from perfect distillation process. If the process would adhere so well to theoretical rules, can you explain the following:
      >
      > a) Why do I get my first smelly drips sometimes starting at 65 C?
      With certain washes, usually fruit washes for me, there are trace quantities of very-low-boiling-point compounds (high partial vapor pressure) that evaporate rapidly enough to be condensed at lower-than-boiling temperatures. I had this occur during  recent stripping runs of fermented apple cider. I made an allusion to this kind of thing during one of our earlier discussion.
      >
      > b) Why don't we turn up the heat to the max to get everything out a.s.a.p. if boiling points and vapour temps don't change/react to power settings?
      If we are doing a "stripping" run, where the goal is to concentrate all the more volatile compounds into "low wines", that is exactly how we run our stills. Then we load those low wines back into our still to perform the "spirit" run, which we do slowly, at least up until the tails, so that we do not "smear" the fractions any more than a potstill will do all by itself. By doing a spirit run, the subjective changes that we look for in the distillate come less quickly, and we can separate the fractions, make the cuts, at a more leisurely pace, but stripping runs are always flat-out runs.
      >
      > c) Why does the ABV change much more than predicted by the ABV of the wash and the connected vapour temp alone?
      It's never appeared to me that it does. I have graphed some of the runs in the tiny teaching still in my book, and even with so small a still charge, and so low ABV a wash, the temperature curve is very close to flat for quite a while. Doing a spirit run in a larger still, I can go a long time at the same head temperature, to the 10th of a degree C.
      >
      > You don't have to answer these questions, they are merely rhetorical.
      >
      > I have studied chemical engineering/process technology at university levels and I'm an electronics engineer.
      It's amazing how similar our backgrounds are.
      >
      > https://en.wikipedia.org/wiki/Chemical_engineering
      >
      > Like I said, results sofar a very good and when the program is finished it will surely help me using my time more efficiently without doing prejudice to the end results. The program will mimic what I do normally by hand, like you said, adjust power levels.
      >
      >
      > To Paul:
      > The influence of air pressure and ambient temperature will only induce a shift in time, the raising temp will, literally, sooner or later, pass the point where I get the desired output.
      >
      > Maybe the (stripping) process won't be faster when I do it 'automated', but since I don't need to sit next to it, I still have more time for other things, even when the distilling takes longer!
      >
      > I thought others here would be interested in something like this as well ;-)
      >
      > Saude,
      >
      > Tomas
      >
      ----snip----
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