"Hi md,
Originally Posted by: Maddawgs Hi Scotty,I had thought that thru the reflux action of the column that it would control separation and by utilizing equilibrium we would actually achieve better separation. <SNIP> let the column re equalize before pulling hearts
This gets confusing. Separation and reflux are not one and the same ... even though one may lead to another.
Reflux is simply repeated vaporization and condensation. It's normally found in discussions of binary mixtures (in our case ethanol and water). Each time our mixture vaporizes, the vapor contains a greater percentage of ethanol than the liquid does. So when that vapor is condensed, those little drops of liquid contains a higher percentage of ethanol. Now if those droplets vaporize again, before they fall back into the boiler, the resulting vapor will have more ethanol than the droplets ... and so on, and so on ... reflux That's how we get our high abv.
However, the mixtures we toss in our boilers are more than just ethanol and water. We have various acetates, ethanol, water, and various fusel alcohols. Just like any mixture, when the liquid vaporizes we'll get a vapor that contains some of everything. So ideally, we want to separate those components into fractions using our column. If we can get, for example, all of the ethyl acetate (and only ethyl acetate) to the top of our column, we can then draw it off -- leaving the other stuff behind until later in the run ... and deal with each component one-by-one. If all we had in our boiler was ethyl acetate and water we could take advantage of reflux and purify the ethyl acetate to a very high percentage and leave most of the water behind.
Now, if we have all those components in there and we turn the power way up (we drive the column too hard) we're just forcing all those components further up the column. If we drive it hard enough we could theoretically cause all of the condensing to occur at the column condenser rather than occurring throughout the entire length of the column. So driving the column too hard has essentially the same effect of shortening the length of the column.
Anyway, once these concepts sank in and I started to adjust my approach to power, cooling water, temps, etc. I started to get better results -- and this was largely, if not completely, due to the patient guidance from Scotty. So I don't pay any attention to specific temps anymore. I'll pay attention to temperature
changes -- but not to specific temps. I just stay focused on keeping my power down to somewhere near minimum, providing time for full reflux, and collection rate (which amounts to reflux ratio).
Regards,
--JB"