Prior to posting I apologize for the bandwidth due to the large post. I welcome any comments or questions about this post considering it seems out of the ordinary in respect to yield.
A little chemistry 101 here, and I'm sure to get bashed over this, but....
Ethanol boils at 172.5 deg. F at SEA LEVEL. Altitude and barometric pressure will make a difference. The % yield that you get will be at it's highest at the beginning of your run, provided all other factors ,cooling water, purity of mash, etc., are equal. After a couple hours you will see the top of column temp ,TOC, raise. You are still getting ethanol ,ETOH, until around 204 deg. F TOC, albeit at a lower %. ,All this is either in a book I read, or on the web somewheres else, and if I have to defend my position by quoting it I imagine I can find the source if I look hard enough., When the % ETOH in the wash decreases, it will cause the temp at TOC to raise slightly ,less ETOH more H2O in the vapor,. My experience, this happens in 'steps'. I get 173 deg. for the most of the run, then jump to 179, 185, 192, 197, then 203 consecutively ,actual figures may vary due to atmospheric conditions, etc,. Realize that my % yield drops accordingly as well, to the tune of 50% when I get to the 197 range.
In practice I usually watch the TOC until it starts to raise above 180 and collect anything after that point up to 200 in a different jug. Sometimes I re-run it, other times I cut it all to 100 proof and drink it.
For example, my last run consisted of 10 gallons of wash from 25 lbs. sugar and Turbo 48. It took about 90 minutes to heat to the point of yield ,where it started to produce, that day 170.5 deg F,. I collected 6.5 quarts of 94% ETOH ,by hydrometer
20 deg C, during an 8 hour run using a turkey fryer burner and LPG. I did do a little 'experimenting' by running my cooling water through a copper coil submerged in an ice bath prior to the water going to my condenser, and it seemed to make a big difference. My return water ,after the condenser, was a constant 82 deg F for the duration that I had ice in the cooler. My TOC temp was 170.5 for the duration of the run, and as I stated earlier, my yield was 6.5 quarts
94% ,and I ain't blind yet.... :-, , I shut everything down instead of running up to the 204 deg. F to save a few $ on LPG. This is my 6th run with a 15.5 gal keg and homemade column, and as far as I can tell, my best run yet for tasteless-ness and odorless-ness. Vive la Turbo 48. Oh wait, I hate the French, they don't support the U. S. anymore.... Turbo 48 is da shizznit!
Laissez le bon temps roulette.....
