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PID temp control for distillation (was Before i ask )

  1. Jul 26, 2010 #1
    PID temp control for distillation (was "Before i ask")

    I am 68 years old and never studied physics-- i am not a college student and only completed 1 year of college.
    I have a hobby of distilling and need questions amswered-- is it ok if i aske questions here about distilling???

  2. jcsd
  3. Jul 26, 2010 #2


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    Re: Before i ask

    Welcome to the PF, Scotty.

    I would think it would be okay. If there are any problems, folks here are pretty good at using the Report button to give a heads up to the Mentors about any issues.

    What-all do you distill?
  4. Jul 26, 2010 #3
    Re: Before i ask

    I dont intend to break any rules-- Well i started making wine a few years back and somewhere along the line i found a distilling website-- I truly almost never ingest alcohol. The hobby is a bit interesting - i use the wine to bribe the handy men in the trailer park.

    Well i really dont remember what prompted me to buy a small still but im in up to my neck now--I have been attempting to make Irish whiskey with barley malt.I have a variac and am putting together a pid controller to controll the heat to the boiler.

    Thats where the confusion comes in. The old timers on the distilling website tell me that i must get the liquid to a boil and then cut back the power so as to maintain the boil and never let the heat source shut off even if it is just on low

    BTW i let my advanced class ham license lapse--Years ago

    Well in my mind i cant see how the liquid knows if the power to the heating element is off or on-- i think that if i got the liquid up to about 200-205 deg.F. the alcohol would boil off even of the power was turned off- Im setting my controll with a 1 degree diferential.

    Is the actual boiling necessary??

    What i want to do is assemble a pID with a solid state relay. Im really green at this pID thing but i believe that i read that the device would cycle the power on and off at diferent rates as the desired temperature was approaching. This would almost eliminate over shooting and wide variations in the temp but not necessarily keeping a constant power tothe heat element.

    If i have not explained clearly i will gladly try to answer any questions--And naturally thanks for any and all comments-- i want to learn if possible:smile:
  5. Jul 27, 2010 #4


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    Re: Before i ask

    The pot will boil at it's boiling point. That will change as you distill out the more volatile components. When you change the setting of your variac, you are changing the power to the heating mantle. Without contacting any surface, like the still pot, the temperature tracks with power but in contact with the still the story isn't so simple. In contact with the still, the temperature of the mantle may change somewhat with different power settings but the pot temperature is regulated by the physical properties of the contents. What will change is the rate at which you produce distillate. Higher power... faster rate. It is possible to superheat the still and produce volatiles that are higher than they might otherwise be, but I wouldn't operate your still in that manner. This usually happens when the level in your pot drops below the level of the mantle.

    Hope you've http://www.ttb.gov/spirits/faq.shtml#s7" Good luck.

    edit. I forgot to add that boiling is necessary unless you intend to use a very low temperature on your condenser and you have loooots of time on your hands. Heck, you could "freeze dry" it if you have the time and equipment.
    Last edited by a moderator: Apr 25, 2017
  6. Jul 27, 2010 #5
    Re: PID temp control for distillation (was "Before i ask")

    Im converting my still to an internal heat element in a week or so. Waiting for the stainless coupling.

    Does any one recomend that i run it at a steady boiler temperature-- I use an alcoholometer to determine what portions of the distilate to keep And I monitor the temperature in the top of the still to see when the best alcohol is present. Prox 78C As the temp rises the purity(amount od fusel oils increases)
    Im am willing to expeiment if anyone can give me some suggestions.
    Last edited: Jul 28, 2010
  7. Jul 27, 2010 #6


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    Last edited by a moderator: Apr 25, 2017
  8. Jul 28, 2010 #7


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    Re: PID temp control for distillation (was "Before i ask")

    Maybe he should also answer whether he plans to fill corresponding british, french, german, italian, chinese, indonesian ... forms.
  9. Jul 28, 2010 #8
    Re: PID temp control for distillation (was "Before i ask")

    Thank you for your comment-- Rather than be policed i have requested that my name be stricken from the site roster..
    My loss but as I told the administratror, i used to go to a church that required signatures etc. I wont submit to that again.
    Again, my loss i had high hopes of learning from you brainy typs..

    Thanks :)
  10. Jul 28, 2010 #9


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    Re: PID temp control for distillation (was "Before i ask")

    The PF has a policy against discussing illegal or dangerous activities (see the Rules link at the top of the page). I'd assumed at the start of this thread that distillation of spirits was the same as making beer or wine at home, which lots of folks do within the respective rules. It's too bad that spirits appear to have different rules, at least in the US.
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