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47853Re: Vacuum Distillation Column

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  • landrover_ffr
    Apr 6, 2011
      Comments inserted bellow.

      > The vacuum pump pulls down to 40 torr, that's what I meant "near" vacuum... why does that scare you?
      Just checking. In my world you either pull a vacuum , or not. The term "near vacuum" got me worried that you had very little idea as to what you were attempting to do. Sorry.

      >I read somewhere that at pressures of 70 torr or less the water/alcohol azeotrope does not exist.
      That sounds familiar. Once the vacuum is removed though it will absorb moisture from the air again I believe. 40 torr is only about 1.5 psi if a remember correct, so not too bad to deal with.

      >If I set the temperature no higher than the boiling point of alcohol at 40 torr could I not get pure alcohol off?
      Nope, still need reflux to achieve the separation. As noted by another poster, the whole "temperature setting" concept is a fools errand.

      > I am looking to scale up the design to about 50 liter capacity. I was planning on using SS scrubbers in the column if I can, but I am unsure of the size of the column and reflux ratio (if needed?).
      Sound like an ok plan. I can't tell you what R/R to run (I could implement vacuum distillation in my software/model and see how it turns out). The key with the vacuum will be requiring less power input.

      >I also read somewhere that it is better to have a wider column when distilling under a vacuum for some reason.
      I've not herd this before. This is usually base on the moler flow rate expected in the column (among other things ;)

      >Any ideas on the height of the column (didn't understand "by as high as particle")?
      Sorry, my bad typing (after few too many glasses ;) I meant to say "as high/tall as practical".

      >I'm trying to avoid getting another engineering degree if possibile :)
      Yes, one is more than enough! I garner the help of two of my mates when things get too serious (one is a chemical engineer, the other and refrigeration engineer (among other things, two much education all together!)

      Hope this help a little. I try too be of more use asap.

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