Info from my scrapbook.

[Icefever]

I've been brewing beer...making wine/cider for years...my keeping of notes about what I did/used/ any info was spasmodic at best.

Now when I bought my Airstill some 6 years back....with the aid of the net I started to read everything I could find on this new hobby of mine.

Then I upgraded to the T500 in 2013, all this time because It's so easy to cut & paste info from the net into a doc file..one for beer...another for wine..a big one for stilling...like a scrap book...so all these snippets of info are still in there.

You guys may have done the same, looking back at some of the bits of info these are the base for what I do now. Then I thought that they may be handy for some of our new members that are starting off...so here goes...


Here's a some what simplified explaination of what's happening inside your boiler...


When you have a mixture of liquids, each with its own boiling point when pure, then the boiling point of the mix will lie somewhere in the middle, and this will depend on the relative concentrations of each liquid. Pure water boils at 100 deg C, and pure ethanol boils at 78.5 deg C, but a mixture of water and ethanol will boil at some point in between.

The major point about distillation is that when a mixture like that boils, then the vapour given off is richer in the most volatile component, and when that vapour condenses then the resulting liquid has a lower boiling point than the mix it came from.By repeating this boiling and recondensation process up a column, using packing to hold the condensed liquid
at each stage, you can separate the components more and more.

So if you have a mixture of liquids each with a different boiling point, then you heat the mixture, it will heat up until the new intermediate boiling point is reached.When you first start a distilling run, the packing in the column will be at room temperature, so vapour given off by the boiler condenses on the first cool packing it reaches. In condensing, the vapour gives up a lot of heat, and this warms that packing until the liquid on it boils again. However, this liquid is richer in volatiles than the mix in the boiler, so its boiling point is lower.

When it does boil again, from the heat given off by more condensing
vapour, what you get is even richer in those most volatile components.
This process of boiling and condensing continues up the column and, because
the condensed liquid is always getting richer in volatiles, the temperature
gradually falls the higher you go. The temperature at any point is governed
solely by the boiling point of that liquid mix, and any attempt to inter
fere with that process will disrupt the separation that Nature is carrying out automatically.

In contrast, the boiling point of the mix left in the boiler will very slowly start to rise as it is left with less and less of the most volatile components. If you started with a mixture (fermented wash) that is mostly water & ethanol, with trace amounts of methanol, propanol, etc. then the net result will be that the most volatile components will tend to risein greater quantity up the column than their less volatile cousins, and will be found in greatest concentration at the top.

This would mean that methanol, the most volatile of the lot, will win the
race and you will able to collect it and set it aside. This continues until you have collected all of the "heads" (components that are more volatile than ethanol), and you can then collect just ethanol with a trace of water.
You cannot get rid of that small amount of water, as once you reach a mix of 96.5% ethanol/water, with a boiling point of 78.2 deg C,then you have reached a stable mix that no amount of re-boiling and re-condensation can change (at normal atmospheric pressure).

Once you have collected the main bulk of ethanol, then the components that are less volatile than ethanol, such as propanol and the bigger organic molecules, will start to reach the top, and you will have arrived at the stage called the "tails". These "tails" may be recycled in the next batch you do, for they still contain a lot of ethanol, or a proportion may be retained as they contain many of the compounds that give a spirit a distinctive flavour, like whiskey or rum.

One more snippet I found...

The alcohols in the wash begin to vapourise from the wash around specific temperatures. If by themselves they would be ...
• Acetone 56.5C (134F)
• Methanol (wood alcohol) 64C (147F)
• Ethyl acetate 77.1C (171F)
• Ethanol 78C (172F)
• 2-Propanol (rubbing alcohol) 82C (180F)
• 1-Propanol 97C (207F)
• Water 100C (212F)
• Butanol 116C (241F)
• Amyl alcohol 137.8C (280F)
• Furfural 161C (322F)


That's all for now...schools out..that sounds like a good song title.

[Easydrinker]

If and when I decide where this is best posted, I may move it, purely 'cos it is a nice concise bit of info.
Thanks.

Robert.

[Icefever]

I'm sure other members must have done similar...I have other bits of info that at the time seemed relevant too what I want to know/find out about stilling.

At times I've thought that the forum could use a section on the science of our hobby.