Hi Scotty,
Wow, no responses?. I'm surprised as I thought this was a pretty good idea and the forum has some pretty smart members. I'll try and help with a few (totally uneducated)thoughts that I hope can help you out.
I'm not sure you can really control the temp of a liquid once a heat source is applied to anything other than a range unless you can accuratley use some sort of heat cycling. If you could control the temp I would try to do it in stages to take off the different alcohols at their vapor points. Going along that line of thought where the temp sensor (thermowell) is placed would not really matter as long as it is somewhere in the center of the liquid mass (because you are heating the entire liquid mass to a certain temp). So you would heat the liquid to around 154f until you had taken off all the foreshots. Next set the PID to heat the liquid to a range of 160f to 170f and let it sit there until you have taken off all (or most of) the heads. For these two first steps you would not really need any real reflux, just take off the alchols at a good rate until they stop (based on the temps these alcohols vaporize). Next set the PID to heat the liquid to a range of 171f to 176f. Here you could get the best use of the reflux system and I think (and I could be wrong) may hit 94% to 96% abv (because at this temp range you should only get the good alcohol). After that set the temp for 180f to 200f and pull tails until they are done. Use them for your next run. I could have this all wrong but I hope it will get some dialog going.
Maddawgs

Hi Scotty, I would imagine you would need a good controlled environment, no wind, insulated column and boiler if you were to go to the trouble, cause I'd imagine your pid wouldn't get accurate readings?. What's the reasoning behind your idea?. Can't you get equlibrium running your still how you do now?. It doesn't take much to achieve equlibrium. Stacking the fractions is equlibrium. Sorry I'm not very switched on with technical stuff, just don't really understand what your trying to do. I'll wait till other comment, might understand better lol.

Cheers

You have a reflux still don't you Scotty?, it should achieve equilibrium. It will be better than a straight out slow run, the fractions will stack better and give you finer cuts with more of the goodness, in theory. I'm pretty new to all this to but that's my understanding, my bubbler compaired to a vm or lm is it will compress fractions better.

"Scotty:

I think you are trying to establish an equilibrium process to batch mode. Your batch is a mish mash of fractions. Each fraction as it boils off, controls the batch (liquid) temperature. Think of the process as if you were trying to only boil off water vapor. No matter how much energy you put into the water, the temperature of the batch stays the same, 212, unless under pressure.

As each fraction boils off, that fraction controls the temperature of the liquid and the temp of the vapor coming off. As that fraction leaves the liquid, the next fraction controls the temp of the boil, and the temp increases. Up to the point when all of the fractions are gone and you only have water, and solids. This temp will go up past 212, as the water is boiled off and you only have a paste left.

So, where to put the thermo-well. I would say about mid-way. It really doesn't matter as you will record the temp of the boil or the vapor above the boil. Which should be pretty close to the same.

I don't think that you will be able to stack fractions in your column unless you are running a pressurized system, and continous process. That is to be continuously adding additonal liquid (wash) as you pull off fractions and waste, also continously."