Compressing heads

[Mash]

by Leatherman » Wed May 23, 2018 10:32 am

Coming back to compressing heads. So if I understand right, this happens not during distillation, but somehow preparing mash before distillation. Where I can not thing anything else apart letting wash to clear. Where I think I understand something wrong here. Can someone give me real example of compressing heads from personal experience. To compare "with compressed heads I got this, and without compressed heads I got this". Many thanks

[Mash]

Ps. I am hoping some clever chaps will be along soon

[Leatherman]

So, correct me if I am wrong, please. If I use reflux still I am getting already compressed heads basically?
Thanks for an answer

[gaza the instructor]

I am probably way off. But here is my slant on this.
Using a reflux column if you keep the column temp
below the boiling point of Ethanol which is 78c,
you will encourage the fores and heads to come off
first, therefore compressing them.

[Leatherman]

That is where things getting interesting. Sorry for grama mistakes typing from phone.
So: if compresing heads is boiling off everything before 78c. If using t500 you only know water outlet temp, which as I read somewhere is 20c lower than a temp in a column. So I guess this information isnt correct. So without aditional thermometer in columnbit wouls be difficult to compress heads. Also not mentioning need of voltage controler. Am I thinking in right direction here?

Second: just to be 120% sure. When we talk about temperatures. We talk about vapor? Not a wash itself in a boiler?

Third thing: influence of atmospheric pressure and being above sea level to this magic 78c boiling point? I do understand that this will have influence, but is it so influencial that needs to be counted in or its minimal?

[Mash]

You would need to be an enormous amount above sea level for 78c to be the boiling point.

https://www.engineeringtoolbox.com/boil ... _1344.html

[Myles]

There are a few different concepts being mixed up all in 1 topic here.

Let us start with a pot still. Heads components are present all the way through the run. You use power management to try to maximize the heads given off early in the run, so that by the time you get to the hearts the concentration in the product is low enough to be acceptable.



By using low power (reduced energy input) the vapour path has a chance to absorb and release some energy to the air. This slightly cools the vapour so that some of the ethanol in the vapour re-condenses into (HOT) liquid and falls back into the boiler. This increases the concentration - compresses - the heads. Too much power in and you overpower the ability of the vapour path to loose heat, it gets hot and all the vapour stays as vapour. No heads compression.

Every other modified still - hybrid - reflux - packed or plated - they all introduce ACTIVE cooling to increase the amount of ethanol that gets sent back to the boiler. Further compression of the heads as these have a lower boiling point and remain as vapour at the temperature established in the still column/vapour path.

You can do NOTHING about the boiler temperature. It will boil at a temperature determined by the mixture of liquids in it. The only thing you can change is the amount of vapour the boiler produces. More power = more volume of vapour.

It is possible, by careful control of fermentation conditions to reduce the amount of heads produced during fermentation, but this is reduction not compression. If you stress yeast with heat, too much sugar, by forcing it to produce too much alcohol, or by making it ferment too fast - these all have a side effect of making the yeast produce more of the products that we call heads. Careful fermentation produces a cleaner starting point for distillation.

There is one other aspect that was mentioned. Pre-treatment. You can reduce the amount of heads that goes into the boiler in the first place. Less in means less out.

For a pot still this usually involves collection of low wines at less than 30% ABV. In this condition they will partially separate out by density. Tails will sink to the bottom of the container and heads will float. It is inefficient (heads and tails are both soluble in ethanol) but if you charge the boiler from the middle section you can slightly reduce the heads/tails components. Go above 30% and the solubility increases dramatically and there is no separation.

For a reflux still you can also manipulate pH and add chemicals that will further reduce heads components - but they are quite advanced techniques that many folks never bother with.

[gaza the instructor]

Mash thats the boiling point of Ethanol not water.

Leatherman my t500 has two therms on it.

Miles so are you saying there is no point in Refluxing
or putting the still into full reflux and holding?
But when using the Alembic copperware I use a controller
to manage the temp. Do not know if this condenses the heads
but it does make the cuts more defined.

[Mash]

Mash thats the boiling point of Ethanol not water.

Yes indeed, but the same applies.

[Myles]

Miles so are you saying there is no point in Refluxing
or putting the still into full reflux and holding?.

NO. Not saying that. There is definitely an advantage to holding in full reflux on a packed column to compress heads when aiming for neutral.

Some folks also do it on plated columns for flavoured product. However, a lot of folks only hold for long enough to load the plates and then start the run.

It really is variable and depends on the equipment used and the product you want.

[gaza the instructor]

Cheers Myles normally hold on full reflux for 30mins
then dail in temp slowly till well into hearts B4 I
let it rise up.

[Maker]

Oh, I do it the other way round, I bring to boil on full power, when I start getting drips I turn power back to my goto spot on my Chinese controller, turn depheleg to max and wait 15 mins, then slowly decrease flow to dephleg until I get a flow at 20C/96%, if the temp goes up I increase the condenser flow, alcohol percentage usualy stays stable all the run, when it drops past 93% I can usualy smell tails so I stop.
Am I doing it the wrong way round, it takes about 4 hours to process 3 gallons of strip watered down?

[Myles]

Oh, I do it the other way round, I bring to boil on full power, when I start getting drips I turn power back to my goto spot on my Chinese controller, turn depheleg to max and wait 15 mins, then slowly decrease flow to dephleg until I get a flow at 20C/96%, if the temp goes up I increase the condenser flow, alcohol percentage usualy stays stable all the run, when it drops past 93% I can usualy smell tails so I stop.
Am I doing it the wrong way round, it takes about 4 hours to process 3 gallons of strip watered down?

Absolutely not doing it wrong. There are multiple ways to drive rigs to the same result - it is just personal choice.

On my packed column I used to warm up on full power until the boiler started producing enough vapour to warm up the column. I would then drop power and put in full reflux to compress the heads at a minimal power level. Take those heads off then put it back in full reflux at my normal 80% of max power to re-stabilise.

Take off just a bit more heads and then go into hearts mode.

[Easydrinker]

Thank you Myles,
Your posts in this thread are worth their weight in Ethanol.
You explain it in a more succinct way than anything that I could attempt.
TBH, if the information is out there and shared, I don't care who was the source.

Robert.

[Maker]

Cheers Myles, it's good to know I'm on the right track, you certainly do have a great way of explaining things, you would make an amazing Youtube host.