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Consistant temp with propane


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We are using a 3 foot tower that can act as a reflux or pot still on top of a 15.5 gallon keg. It's heated by a Bayou Classic 210,000 BTU burner. See picture below. The issue we are having is keeping the temp consistant. We get it up to 170F, but we can't keep it there. It will rise and then we turn the gas down a hair (literally) and the temp drops and the same goes the other way. Is there anyone that has had the same problem and has a remedy? I'm not sure how to remedy this except to run electric with a voltage meter to regulate temp.



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Weeeeelllllllllllllllll, we are putting the finishing touches on our business plan. We just received the last of the figures needed to complete it. In 2-3 months we will be entering the licensing phase of our opperation. So, to answer your question Coop and Scott, we are in a secret location until our warehouse space is finalized.


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What you are describing is PROPORTIONAL burner control, sometimes called Modulating. This style of setup uses a proportional valve (a needle valve, like a kitchen tap, can vary the flow, as opposed to a ball or shutoff valve) usually electrically controlled with either a motor, or a modulator (not going into that depth here :-). A temperature controller (or PLC) senses the pot temperature and continually adjusts the proportional valve to vary flame height, and thus the energy input.

They work beautifully, but are much more complex than a simple burner dafty control. Honeywell and Asco Valves are big players in the market. Our smaller stills are gas fired and we have 4 stage burner control (off, 1/3, 2/3, full on). The controller ramps up and down the burner intensity as needed. Stepped controllers like these are cheaper than full proportiona, but may not give you the granularity if control uo need. This style of control also allows you to fire the burners at full to boil up, then reduce down for the run.

The temperature controller must be able to be programmed with the thermal curves of your pot (some smarter ones actually learn on th ejob) They will cut in and out the burners, ahead of time, preventing temperature overshoots.

You will still need the standard gas control train (pilot control, ignightor, safety cutouts etc)

APPROX Costs (Aussie $$, so expect much cheaper in the US of A)

  • 4 stage modulating valve to suit a 500k.BTU burner: $350 --or--
  • Fully proportional valve: $600
  • standard gas train: $250
  • Good learning Temperature controller: $300
  • Stainless temp sensor and well: PTC $75

Although not essential I would add an IR flame detector and buzzer to detect flame out

Any good industrial gas equipment supplier should be able to make you up a kit.

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Correct me if I'm misunderstanding, but you seem to be confusing heat and temperature.

The measured temperature at any point in your distillation apparatus (assuming that distillation is under way) has pretty much nothing to do with heat input.

The measured temerature at any given point in your apparatus is directly related to the proportion of alcohol and water in the azeotrope at that specific point (e.g. the ABV) and its phase (i.e. liquid or vapor)

For example, if you had a thermowell in the pot (which was full of 10% ABV wash), the bottom of the column, the middle of the column, and the top of the column, and you were collecting a distillate at 190 proof, the following would be the respective temperatures, regardless of heat input:

pot: 93 degrees C

bottom of column: 93 degrees C

middle of column: 86 degrees C

top of column: 78 degrees C

This link will give you more detail, and has a very important graph to understand: http://homedistiller.org/theory.htm

In your picture I only see one thermometer in your column, and it's in the middle. You should not expect to ever see a constant temperature at that point any lower than approx 86 C.

Perhaps you already know all of this and I misunderstood your question? If not, you should study some distilling theory which is readily available on websites such as the link above before you go commercial. You also might want to run the numbers on how much labor will be required to produce a commercial quantity of alcohol on a 15.5 gal still.

Happy distilling!


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