Using a Fractionating Still

One of the best descriptions of running a reflux still, is Husker's Post on the forum. That post is the 2nd or 3rd one in this thread.

The difference here is the need to really equilibriate the column at the start of the run, so that the methanol gets to accumulate at the top of the column, and to get all the packing in the column up to its equilibrium temperature so that it will work its best. This can take from 1-4 hours.

To get a fractionating still to work at its best also requires quite a high reflux ratio - returning 8-12 times back to the column vs that which is kept. To do this means knowing what the total rate is, then trimming the offtake valve to only take a portion of it. Do this by opening the valve fully and measuring how fast it is coming out, then closing down to only take what you should. Once you know this setting (say 1 drip per second), it will be the same for future runs.
If you have an W heating element, and you are collecting the distillate at mL/min and at %
the distillate flowrate would be mL per minute if you were to reflux none of it, but you presently have a Reflux ratio of

Using the collection calculator back up the page, you know how much alcohol you have to collect, thus it is easy enough to work out how long its going to take. You may figure that its not worth waiting quite so long, just to gain a couple of 0.? % improvement in purity. Experiment to find a reflux ratio that still gives you a suitable purity, without having to wait forever.

I control my still only by adjusting the reflux ratio. It will happily sit between 78.2 C and 78.4 C for most of the run with a low reflux ratio, but towards the end, the reflux ratio will need increasing more and more to hold it there. As this happens, change the receiving container, and keep the tails seperate.

Randy writes ...
    The most important aspect of observing temperature is to make sure that you do not save any foreshots as beverage. Anything collected before the still head reaches 172 F (77.8 C) should be discarded or used as charcoal lighter. From there on you would be better off using your nose to detect if the heads are finished or not. Then experience will tell you when the tails start coming over. Some people save more tails into their product than others. This is according to taste. Of course everything I just typed about flavor is assuming that you are using a grain mash. If you are using a sugar wash, then the nasties that make you use carbon treatment are in the cogners.

    For me I let the still equalize in total reflux for 2 hours and then draw off the foreshots and then let it equalize for another 1/2 hour. Then I draw off the heads until I cant detect a foul smell. These I save and add to a container labled "faints". Then I distill the middle run and a portion of the tails. I run this phase until I reach 75 pct ABV. These are saved in my 'product' containers. Then everything else is distilled out until 65 pct and placed into the feints container. Then I distill everything else out of the wash that I can get. I stop when still head temps reach 205 F (96C) or so. Everything in this portion goes into a container labled 'redistill'. If you 'throw everything away' then you will be sending perfectly good ethanol down the drain. It might not be beverage quality right now, but it will be excellant stock to make a clear vodka from.
Ken describes his technique ..
    I usually strip 50ltrs and end up with around 18 ltrs @36-40%,this is from 2 fermenters of sugar wash,I then set up and turn on around 11pm and go to bed.Next morning the tower is in a state of total reflux and I start taking the fore shots off around 6-30 am,by 8am everything is coming over @ top % and I keep an eye on it and change jars every 2 ltrs and know when it is about time to expect the tails to start coming over. If you have unexpected guests arrive during the day I usually just turn the temperature down by 10 degrees or so and wait for them to go then turn it back up again and you are soon back in production,the same thing also if you haven't finished at night and you do not want to leave it running while you are asleep,just turn the temperature down by 10-15 degrees.I know a lot of our members will say I am mad for leaving the unit unattended but I have put a lot of effort into my control systems and am very confident in this setup,the next thing to add is a pressure switch that will turn off the power to the kettle if I have a cooling water failure.


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