Compression

[jdetechguy]

What does it mean to compress heads or tails?

[Kegg_jam]

Look at this first.

http://homedistiller.org/forum/viewtopi ... 63&t=13261

[Sungy]

was gonna send the same link.

[jdetechguy]

Thanks guys. I could not locate this one.

[FreeMountainHermit]

What does it mean to compress heads or tails?

Look at this first.

http://homedistiller.org/forum/viewtopi ... 63&t=13261

I'll be running a two plate flute this year for the first time and was thinking about posting the same question.
In the few years that I've been a HD member I've read the suggested link a few times and can't find where "compression" is discussed to any great degree so I'm basically still in the dark regarding this.

Help please, FMH.

[Kegg_jam]

Ok.

So reading through the link it has some cool graphics showing the natural smearing of heads into hearts and hearts into tails.

Now imagine a really small heads portion with a more defined transition into hearts, and same with tails.

So the end result being a larger, cleaner hearts cut with some real nasty shit on either end.

I just like the graphics in that thread and it's worth a read through.

[jdetechguy]

I read through this section thorougjly, twice. There is no mention of the word compression, nor even really much of a hint. They mentioned and defined smearing which is great. The also discussed wide cuts and deeps cuts, which I will do more research on what that means.

But, I can surmise from the meaning of compress, I gather that it means to squeeze or shorten heads or taiks, in favor of more hearts? Is this correct?

[jdetechguy]

Bad typing from my phone today. Sorry about the typos.

[FreeMountainHermit]

Yup,saw the graph KJ and understand about bring a column into equilibrium to compress things but I'm still driving my column in the dark so to speak.

BTW, the graph in my feeble mind deals more with cuts.

Appreciated your input if you or another member would care to open a discussion here, PM or even by phone if that's cool.

TIA, FMH.

[FreeMountainHermit]

I read through this section thorougjly, twice. There is no mention of the word compression, nor even really much of a hint.

BINGO !!! Winner,winner chikken dinner.

[rgreen2002]

Ok.

So reading through the link it has some cool graphics showing the natural smearing of heads into hearts and hearts into tails.

Now imagine a really small heads portion with a more defined transition into hearts, and same with tails.

So the end result being a larger, cleaner hearts cut with some real nasty shit on either end.

I just like the graphics in that thread and it's worth a read through.

+1 KJ

With my 2' Boka I get great compression of the tails... I guess I get heads compression as well but I don't notice it as much...

When I run the Boka I take the fores as usual then reflux a little. When I take the heads there does seem to be a definite change in taste/smell moving into the hearts... I mean like nail polish to delicious in a few drips... Its kind of like if you add sodium carbonate to the low wines before a spirit run. The way that really gives a defined change to the heads/hearts junction is similar. Cleans it up a little.

The hearts runs for what seems to be forever and then the tails rolls in and it is the essence of evil! It smells terrible...ultra concentrated tails smell..like hot death. It is the worst tasting stuff ever and I have to admit I have never put it back into the feints jar (I actually have very little in the way of feints with the boka).

The real interesting thing is that while I'm collecting hearts in the high 90's ABV as soon as the tails kicks in the proof drops 10-15% in a very small volume (usually less than 200ml)

So I think of it as extracting all the good stuff and concentrating all the bad... hope that helps.

FMH...I'm with you... Proud new flute owner who cant wait for band camp!

[frunobulax]

Try searching Equalibrium http://homedistiller.org/forum/viewtopi ... 15&t=44263 the longer the coloumn stays in equalibrium the tighter
the fractions "compress" and are drawn off easier. A plate column with only 2 plates won't compress as much as a packed section because it doesn't have the
same surface area. that's why if you want a neutral in a plated column, ya gotta add more sections / plates.

[FreeMountainHermit]

Thanks frunobulax, I will read that link later today. I think it's finally starting to penetrate my thick head.

I thought I'd start out with two plates at first to learn but I do have a 4 plate section that I could slide in for a total of 6 as well as a 24 inch section that could be packed with various media and added as well.

[jdetechguy]

Ok.

So reading through the link it has some cool graphics showing the natural smearing of heads into hearts and hearts into tails.

Now imagine a really small heads portion with a more defined transition into hearts, and same with tails.

So the end result being a larger, cleaner hearts cut with some real nasty shit on either end.

I just like the graphics in that thread and it's worth a read through.

I understand now. Thanks for the explanation.

[honeybeerbadger]

such an old thread i wonder if anyone will respond.
i've done around 6 runs on my packed column.
i learned a lot this time.
if my vapor temp rises i close the valve until the vap temp drops back down.
nearing the tails i close the valve until vap temp goes back to 77.9 or 78.1 which gives me 95%. closer i get to tails more time i will either close valve or slow drip down. all the time keeping power at 100%.
closing valve compresses it and purifies the etOH.
that is my opinion.
i tried getting a purer product by just lowering the power until dripped slower, not as effective as full power and then later closing adjusting valve drip. 45 inch packed column. using ice cold water. 1500 watts.
closer to tails means drip approx 3gtts/second. in the middle of hearts the drip rate wide open near 1800cc/hr.

[still_stirrin]

..if my vapor temp rises i close the valve until the vap temp drops back down.

—> nearing the tails i close the valve until vap temp goes back to 77.9 or 78.1 which gives me 95%. closer i get to tails more time i will either close valve or slow drip down. all the time keeping power at 100%.

—> closing valve compresses it and purifies the etOH...that is my opinion.

—> i tried getting a purer product by just lowering the power until dripped slower, not as effective as full power and then later closing adjusting valve drip...

HBB,

You didn’t say what type of reflux management you use, but it sounds like it might be a VM (vapor managed), where you control the reflux ratio by adjusting the vapor takeoff valve.

When the heat is maintained (high) and the vapor takeoff valve (VM) is closed, the still is in “infinite reflux”, meaning all the vapor produced is condensed and returned down the (packed) column. The rising vapors reboils the falling condensate, carrying the constituents with higher volatility upward again. And the heat transferred to the falling condensate causes the vapors with a lower volatility to condense and return to the boiler. This reflux process “stacks the column” and results in purer vapors progressing to the product condenser.

The liquid modulated (LM) stillhead is very good at compressing the heads. The LM design condenses ALL of the vapors all of the time, but allows you to draw off the condensate at a slow rate, keeping the product proof very high, at least in the start of the run. LM’s are traditionally slow producers because you condense all of the vapors in the reflux condenser all of the time. But they will produce very high purity products as a result...ie - very high reflux ratio.

The VM stillhead is very good a compressing the tails, or pushing the tails to the end by keeping the reflux ratio steady as set by the VM valve position. Once set, it is a stable (high proof) producer. And as the tails approach, when the vapor temperature will rise, the VM will slow production to the product condenser.

With a coolant managed (CM) stillhead, the reflux ratio is managed by the coolant flow to the reflux condenser. And to some degree, the CM is also controlled by the boiler heat input, although heat input really just adjusts the vapor production rate, ie - more heat —> more vapor produced and when properly condensed in the reflux condenser —> higher reflux ratio (higher purity) and a higher proof at the spout.

The difficulty with a CM stillhead is that as the run progresses, the temperature of the vapor will rise and the heat transfer in the reflux condenser will vary, requiring adjustment of the flow rate to keep the reflux ratio steady. As a result, the proof will decline at the outlet just like a potstill because of the declining reflux ratio (RR).

VM stillheads are the easiest to run because the RR is set by the valve position and as the vapor production varies, the split between the reflux condenser and the product condenser will always be constant (by the valve position), so the proof will stay constant. As the alcohol in the charge depletes, vapor production will slow, so keeping the heat input high helps ensure the RR stays high as well.

In conclusion, your observation that keeping your heat input up will help hold the RR up and keep the purity offstill high is correct. “Running low & slow” is an expression more related to potstills, and to some degree CM stillheads because it allows a finer degree of separation (less smearing) of the fractions through the run.

So, sorry for the long dissertation, but hopefully it helps explain the way your still operates and the observations you’ve experienced.
ss

[honeybeerbadger]

This first comment here on top is about compression and follows everything below: but want the compression question to take priority.
1. my question: i finished making neutral with my vapor management unit and now am distilling gin botanicals with the neutral spirit and a lot of water to cover bottom element. my question is....I removed the packing and noticed that the vapor temp goes crazy higher than when it is full of packing. so i am asking... do i need to close the valve and try to compress it? or should i just let it trickle out at full power and not care at all about vapor temp? (after the forshots). when distilling neutral with gin botanicals pot style... is it wise to close valve a bit and try to get vapor temp closer to 78.2C? or perhaps it completely does not matter because after the foreshots who gives a shit....just distill that gin.!!! thank you.


fantastic. yes i've a vapor management i think. boka reflux? alcoengine packed column with condenser built into the top 4 inches or so.
your comment sure is correct about this style being fantastic at compressing the tails. i went from 94% smell taste great to horrendous noxious tails super quick. not much gradual. the drip rate slowed down a bit before the tails and then wham! all done.
I understood all that you explained and am aware of most of those details. it is rare to find a great gem advanced insight though.... i wish to find gems about compressing the heads more. i cannot distinguish heads very well. with 50 litres of 11% sugar wash then stripped to 80% low wines and then refluxed to 95% I don't know any tricks to compress the heads except to be very patient for the column to equilibrate. just wait between 15 and 40 minutes before taking off. and then just decide to put aside 100cc 200cc 200cc and smell them the next day whether to include. (excellent advice i found before deciding).
I'm finished making the pure neutral and now added botanicals for gin and removed packing.
i was shocked to see it dripping around 20 cc at 60C. i through that away and now at 1500watts and no packing the temp went to 93%. set aside 100cc. and then i figure i'm safe with the rest of the 900ml of 94% mixed with 20 litres water and gin botanicals. (20 litres to cover the lowest element in the 57litre sanke keg). oh how i wish i had an element that fit under the keg so i dont have to dilute the gin wash sooo much.
pot still style making gin such an entirely different animal. i'm toying with lowering the power because vapors at 93% i fear might be too much power for this small 21" vapor managed column 2" wide. back the power off. i think last time it couldn't cool and condense it fast enough. without the packing it doesn't compress i think?

[still_stirrin]

... i've a vapor management i think. boka reflux? alcoengine packed column with condenser built into the top 4 inches or so...

The Alcoengine reflux still is a LM still...you adjust the reflux ratio by the liquid takeoff rate. The LM still is exceptional at compressing the heads as well as holding a high proof offstill. But it is a very slow operating still.

A VM still has a valve that splits the vapor flow between the reflux condenser and the product condenser. But the key here is that it is vapor that the valve passes, not condensed liquid.

...I'm finished making the pure neutral and now added botanicals for gin and removed packing....oh how i wish i had an element that fit under the keg so i dont have to dilute the gin wash sooo much. pot still style making gin such an entirely different animal...without the packing it doesn't compress i think?

So, if you’ve been successful at making a “clean neutral” for macerating the botanicals, then you don’t have, or shouldn’t have any “heads” left in the boiler to compress. I suggest reading through Odin’s EZ gin recipe in the Tried & True forum to better learn how and when to make cuts for a gin run. Juniper character comes over very early in the run, so if you cut out too much, you’ll lose a lot of the juniper aroma and flavor, which is fundamental to a gin.

Also, if the volume of your gin base is too small for your keg boiler, then I strongly urge you to make a small stock pot potstill that you can run from your stove top or a hotplate. I have a “purpose built” stock pot potstill for exactly this reason. It allows me to make 2 liters of gin very easily. And, it’s a potstill, so no reflux is needed because the gin base is always a clean (hearts cut) neutral that is typically double distilled already.

Think, “right tool for the job” and you’ll find the job is a lot easier.
ss