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Appleton/Wray: An inside look at their distillation...

 
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Capn Jimbo
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PostPosted: Mon Aug 31, 2015 7:30 am    Post subject: Appleton/Wray: An inside look at their distillation... Reply with quote

A matter of history, tradition and pride...


Although rum as we know it in the Caribbean first emanated from the now destroyed Mount Gay, it was Jamaica who made the first important steps toward fine rums. Here's why:

Double distillation has been attributed to the expat Brits who found themselves in Jamaica, where the first, classic and still existing so-called "rum stills" were soon instituted and surprise! Are still being used today. Check these out...

. . . . . . .
(...a historical, classic Jamaican double retort pot still)

From right to left, the wash is vaporized and is delivered to the bottom of the "low wines" retort. The vapor bubbles up through the retort to arrive at about 60% alcohol vapor, which in turn is delivered to the bottom of the "high wines" retort. In like fashion to the first retort, the vapor bubble through and is further rectified to about 90%. This vapor is then delivered to the stainless tank which is a classic worm-in-tub condenser. Note that the pot itself is heated by a brick oven.

In practice the still master tastes and smells the output to capture mostly the hearts (but will also contain some crossover heads and tails). The low alcohol (low wines in the first retort) and higher alcohol in the second (high wines) both build up, and typically a portion of one of both are drained back into the pot still (to be redistilled).

In the Jamaican method dunder is often added to the original ferment and/or to the wash in the pot still.

. . . . . . .
(...currently in use at Hampton Estates)

Same idea as the classic setup, but much larger and this time using what can be called a shotgun or tube condenser (which has a cool water jacket), rather than the old-fashioned worm-in-tub).

. . . . . . .
(...a black and white pic of part of J. Wray/Appleton still)

Don't be misled by the black and white photo, as I am confident the pot still is made of copper. This is clearly more modern as the pot still's base is surrounded by a steam jacket for even heating. The pot is topped by a short cylindrical neck which allows some of the vapors to condense, drip down and be redistilled.

Difford's describes the J. Wray/Appleton method as follows:

Quote:

"The Appleton Estate, the oldest sugar estate and distillery in Jamaica, has been in operation since at least 1749 and is now owned by Wray & Nephew. It is situated in the middle of the island in the lush Nassau Valley through which the Black River flows. The company’s sugar cane fields cover 11,000 acres of the valley and the large plant on the estate, which processes the cane to produce sugar, also includes the famous distillery which converts the by-product molasses into rum.

The pot stills used at Appleton are of a type unique to the island. They consist of a copper kettle, a high wine retort and a low wine retort and a condenser. Wash containing approximately 8% alcohol is placed in the kettle and is boiled by steam. This produces a vapour of around 30% alcohol that travels through the swan neck into the first retort where it is bubbled through spirit at 30%. The vapour is enriched and leaves this still at 60% alc./vol. to pass through a second retort that contains spirit at 75% alc./vol. The final distillate or rum emerges at 80%-90% alcohol. This is a very economical pot still distillation, being triple distilled in one pass and with some 80% of the run being taken as the final cut.

Appleton rums are barrelled at around 80% alc./vol. with 1/4 to 1/2 a pound of toasted American oak chips added to each 190 litre barrel. They are married in ‘mother vats’ which are maintained at a minimum of 40% full to ensure consistency in the blend."

http://www.diffordsguide.com/beer-wine-spirits/spirits/rum-and-cachaca/BWS002132/appleton-estate-30-year-old

For those readers who lately have questioned Barbancourt's Coffey Patent Still, it is important to note that the Coffey was simply an outgrowth of the Jamaican retort method and/or the French Charentais semi-continuous method, wherein new wash, and/or high/low wines are returned to the pot).

Mind you - depending on the number of plates and set-up - a Coffey can be set up to mimic multiple pot stillings (as above), or also to produce 95% vodka.
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The Black Tot
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PostPosted: Tue Sep 01, 2015 6:25 pm    Post subject: Reply with quote

Great post.

NOW, I'm going to come forth with some stupid questions.

I ALMOST understand this, so hopefully my asking some amateur questions will give you an idea on where you might be losing the beginners here, since I know it is your aim to raise all ships.

Firstly, coming from a bourbon start, if anyone else is also coming from there, we're confused with the terms wash and wort.

Wort in malt is the sugar-rich liquid which is drained out of the mash tun (basically heated vat) where the grains are soaked and heated until the sugars infuse into the water. In bourbon, the grains stay in what becomes the "distiller's beer" or mash for the fermentation process. In malt, they don't.

Since in rum we're dealing with cane juice or molasses, what's the deal with rum wort? Since the juice/molasses are already a liquid, is the wort in this case just those things diluted with water to a certain degree? What degree? In short, wort the f are we talking about here? (couldn't resist)

Once wort is fermented, it becomes "wash", which is analogous again to the bourbon world's distiller's beer.

This terminology (and how it differs between spirits) is a lot of what has stalled my (and I suspect a few others') sharper grasp of the whole distilling process.

OK, so then we get to the pot, which is the first stage of heating the wash...

To break it down to the basics for new readers (and to check my own fuzzy understanding here), when you heat up wash/distiller's beer, alcohol boils first, at a lower temp than water, so distilling is the art of capturing the flashed off alcohol leaving the water and (in bourbon's case) mash residue behind.

So the wash is boiled in the pot and then rises up through the "retort" (f'ing hell. Let me find an easy definition of a retort - OK, so the retort is the inverted funnel at the top of the pot including the >90 degree elbow in the top. In other places this is called an alembic (cripes - you see why this is tough to get straight? Er, keep bent?)).

The first boil-off of the wash/distiller's beer goes up through the retort/alembic and ends up bubbling through a relatively cooler (but still hot) tank of "low wines" - basically the first distillation stage with alcohol up around the level of (in reality slightly stronger than) most wine. This is because the boiloff process isn't as picky as we'd like and a lot of water still gets up the retort with the alcohol.

At a recent tour of the Kilkerran distillery (Glengyle), something was mentioned that caught my interest. The stills there were bought from a shuttered distillery called Ben Whevis (not to be confused with Ben Nevis - I asked). The retorts on these stills are VERY tall, and the guide said that this gives a lot of opportunity for the boiled wash to condense and start to sink back down through the upward flow of the boiling alcohol vapor. This results in a sort of turbulence which he described as "reflux" - this caught my attention because the word reflux is used sometimes to describe why the El Dorado wooden pot stills are so special (apparently those have some very unique and important reflux characteristics which, when operated with a skilled hand, result in some very special stuff). Apparently reflux results in a lighter, more floral whisky. I was trying to come up with how this turbulence would physically affect the distillation, but I came up short. In other words, I (think I) know tall retorts encourage reflux, which leads to a lighter and more floral result, but I'll be damned if I know how or why - is it because the "heavier flavoring" molecules which are also represented later as the tails have a harder time escaping a higher chimney due to their comparative mass, and mostly fall back down into the pot?

Much ado is made about the specific shapes and sizes of alembics/retorts in the whisk(e)y/rum/spirits world. I'm sure it's been the basis of many a good fist fight.

At this stage, I'm unclear at how it makes it to the next tank. Is it again heated in the low wines tank? Ah yes - in the Hampden picture I can see what looks like steam jackets around the low and high wines tanks, with what appear to be stainless pipes for delivering steam coming in through the top. In the top pic, the heating mechanism is not so easily observed. Are the pipes coming off the bottom of these wines tanks for the delivery of a heating medium/fuel or are they for shunting some of the wines back to the pot?

So we basically heat again, and more alcohol jumps out, leaving more water behind at each stage, thereby concentrating the abv of the liquid.

For some reason, out of the low wines tank, we don't have a retort/alembic, so much as we have a basic pipe. Question: Why not a second alembic with a similar shape?

I think it's confusing to call the 2nd and 3rd stages "retorts" if the retort is by definition the bendy pipe connecting the tanks (am I wrong about this?). Low wines tank, high wines tank, and mention of the additional heating stages in these might help the beginners. Just in preparing this post I'm learning things by forming these questions, which is part of why I'm doing it.

Once we've gone through these three boil-offs (original pot, low wines, and high wines heated tanks), the first parts of the now high-proof alcohol that boil off are known as "heads" - these are undesirable, and contain lots of the crap that was infamous for making amateur moonshiners blind. These are somehow shunted out of the system (not sure precisely through which conduits in the apparatus above?).

Heads and heart are determined by measuring the specific gravity of the condensed high proof spirit, often observed by a floating graduated device (such as we use for our sugar tests here on the project). These SG meters are viewed through a small enclosed windowed box also known as a "spirit safe".

Once the SG increases to the point at which the start of the "heart" (the good stuff) is found, the produced liquid will now be shunted into the "keepers" tank, basically.

Right. After the heart spirit has passed through and been captured, you have another undesirable component of the alcohol known as the "tails". Heads and tails together are grouped into "feints", which can be said to be the combined undesirables of heads and tails.

An important part of the role of distiller is choosing when to start and stop capturing the heart of the distillation. As I understand it, cutting in too early (too low a SG, too many heads included) will result in a very estery, wild beast, headache-inducer of a product - HOWEVER, the chemistry involved in aging spirit in oak barrels does a good job of taming this, which is why cuts with more heads respond well to longer aging in oak, where those heads are developed into longer chain molecules which result in some very complex and delightful flavors. Since we're talking about Jamaicans today, I'm supposing these guys are used to including about as much heads as they can possibly get away with, because as a category Jamaican rum is famous for its relatively high ester content.

Adding dunder to wash is analogous to what in bourbon they call the "sour mash method" - a highly popular process in which a certain volume of leftover distiller's beer sludge aka "backset" is added to the fermentation tank to goose the fermentation or otherwise propogate the development of other flavors during the fermentation process.

Dunder is just more inherently disgusting in nature, seemingly born of a quest to figure out just exactly how gross you cold make a liquid, and then taking that to the next level Smile Whatever. Some of the world's most wonderful vegetables we must remember are grown in manure. Eat and drink up.

Questions that remain foggy to me:

1. As the distillation process goes on, the leftovers in each of the pot, low wine and high wine tanks must increasingly be made of water/larger molecules. When we say that alcohol "comes off the still" at a particular proof, doesn't that proof gradually decrease over time as the wines heat up and more water tags along to the next stage?

2. You mention that a portion of the low and high wines get passed back to the pot still for redistillation - what is the reason for this?

3. Why is this called "double distillation", when the liquid seems to be heated and captured 3 times?

4. Copper is utilized as much as possible in order to remove some ugly compounds, which happen to adhere well to copper. Particularly sulfur. What I don't understand is how copper continues to work on the inside of pipes without being scrubbed clean after each pass, which by the looks of these stills isn't practical. What I mean is, sulfur reacts with copper, I get that - but then it forms an oxide layer. Surely after a still has been run for a while, that copper oxide builds up until the vapor is mostly in contact with oxide rather than fresh copper, which to my mind wouldn't react very much. How often are the internals of these pipes scrubbed/buffed such that fresh copper is exposed for sulfur absorption? I can see access holes in the tanks, are these buffed from the inside to bare copper between each run? It doesn't look practical or even possible to buff the insides of the retorts.

5. What other compounds other than sulfur does copper ameliorate?

I think that's probably enough questions for a vigorous start.

I hope you've enjoyed (and perhaps benefitted from) this amateur regurgitation (reflux?) as much as I've enjoyed working through it myself.
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Capn Jimbo
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PostPosted: Wed Sep 02, 2015 6:01 am    Post subject: Reply with quote

The Black Tot wrote:
.

NOW, I'm going to come forth with some stupid questions.


Keep in mind you are questioning Moi - the Compleat Idiot of Rum. But I'll do my best, great post, thanks...




Quote:
Wort in malt is the sugar-rich liquid which is drained out of the mash tun (basically heated vat) where the grains are soaked and heated until the sugars infuse into the water. In bourbon, the grains stay in what becomes the "distiller's beer" or mash for the fermentation process. In malt, they don't.

Since in rum we're dealing with cane juice or molasses, what's the deal with rum wort? Since the juice/molasses are already a liquid, is the wort in this case just those things diluted with water to a certain degree? What degree? In short, wort the f are we talking about here? (couldn't resist)


As I understand it, fermented cane juice is filtered before stilling to remove miscellaneous detritus. As for molasses based rums, one of the BIG issues are the many solids inherent in the wort/wash, which can end up burning and collecting in the bottom of the pot still, particularly those that use direct flame or heat.

Some single malt pot stills have a device that amounts to a series of chains that are caused to rotate around the base of the still, to prevent this accumulation and burning. For rum, this simply means giving the still a good cleaning after every batch or two (which is why pot stilling is expensive).

Quote:
To break it down to the basics for new readers (and to check my own fuzzy understanding here), when you heat up wash/distiller's beer, alcohol boils first, at a lower temp than water, so distilling is the art of capturing the flashed off alcohol leaving the water and (in bourbon's case) mash residue behind.

So the wash is boiled in the pot and then rises up through the "retort" (f'ing hell. Let me find an easy definition of a retort - OK, so the retort is the inverted funnel at the top of the pot including the >90 degree elbow in the top. In other places this is called an alembic (cripes - you see why this is tough to get straight? Er, keep bent?)).


Quote:
The first boil-off of the wash/distiller's beer goes up through the retort/alembic and ends up bubbling through a relatively cooler (but still hot) tank of "low wines" - basically the first distillation stage with alcohol up around the level of (in reality slightly stronger than) most wine. This is because the boiloff process isn't as picky as we'd like and a lot of water still gets up the retort with the alcohol.


Another example of the rubbery words used. In the pics above the "retorts" are the two smaller pots/containers that are situated in series, and as used the term does NOT refer to the alembic/pot still. Thus the vapor from the pot still passes in turn through both of the secondary retorts before reaching the condenser. This is really a matter of common usage rather than dictionary definitions. Technically anything that distills a liquid could be called a "retort" (particularly the glass versions used in chemical laboratories) - but in practical use - a pot still is called, well, a pot still. An "alembic" was the historical term used for the beautiful, hand tooled and graceful copper stills, still made in Portugal, et al. The difference between a "pot still" and "alembic"? None really. The most used term? "Pot still". Although technically an alembic/pot still could be called a retort, this usage is rare. In practical use in stilling of rum or whisky, the term "retort", which may be referred to as "copper refining recipients", refer to secondary, in-line components which are just the "pot" part of a "pot still".

Trust me, if you start calling a pot-still/alembic (or any of its four parts) a "retort", you're going to get a lot of blank stares from most distillers. Clear as mud, eh?

Quote:
At a recent tour of the Kilkerran distillery (Glengyle), something was mentioned that caught my interest. The stills there were bought from a shuttered distillery called Ben Whevis (not to be confused with Ben Nevis - I asked). The retorts on these stills are VERY tall, and the guide said that this gives a lot of opportunity for the boiled wash to condense and start to sink back down through the upward flow of the boiling alcohol vapor.


The term "retort" means "return", but is being misapplied. A pot still/alembic has four basic parts: the "pot" (literally), the "neck" (aka "swan neck") which is a smaller chamber situated just above the "pot", the "lyne arm" which is the small tube or passageway leading the vapors more or less horizonatally, to the "condenser" (a large container or chamber filled with cool water, through which the vapors pass through within a coil or series of usually copper tubes).

The part you are calling a "retort", is actually the "neck" - these come in all shapes and sized, some squat and short, some taller and narrower. The taller the neck, the more likely that some of the vapor will condense near the top of the neck and drip back down toward the pot (this return/retort of liquid is called "reflux"). The refluxed liquid is then redistilled and the vapor is more refines.

Quote:
This results in a sort of turbulence which he described as "reflux" - this caught my attention because the word reflux is used sometimes to describe why the El Dorado wooden pot stills are so special (apparently those have some very unique and important reflux characteristics which, when operated with a skilled hand, result in some very special stuff). Apparently reflux results in a lighter, more floral whisky. I was trying to come up with how this turbulence would physically affect the distillation, but I came up short. In other words, I (think I) know tall retorts encourage reflux, which leads to a lighter and more floral result, but I'll be damned if I know how or why - is it because the "heavier flavoring" molecules which are also represented later as the tails have a harder time escaping a higher chimney due to their comparative mass, and mostly fall back down into the pot?


That's a fair description. Think about the lyne arm as well. If it slant upward for a way, the output will be lighter; if it slants down, a heavier output can be expected. I will only disagree in that I would not necessarily generalize that a taller neck will result in a more floral output, as pot stilling in general leads to a notably heavier spirit in general.

Quote:
At this stage, I'm unclear at how it makes it to the next tank. Is it again heated in the low wines tank? Ah yes - in the Hampden picture I can see what looks like steam jackets around the low and high wines tanks, with what appear to be stainless pipes for delivering steam coming in through the top. In the top pic, the heating mechanism is not so easily observed. Are the pipes coming off the bottom of these wines tanks for the delivery of a heating medium/fuel or are they for shunting some of the wines back to the pot?


This is an EXCELLENT question. Let's start by considering the simplest pot still/alembic which leads directly to a condenser - no intermediate retorts at all. The first run is a sort of stripping run (often done in a larger pot, which some call the stripping still), which results in an output of about 35% alcohol ("low wines"). This is often a fast run, as the idea is simply to capture alcohol in general. This first run then becomes the wash for a second run, sometimes in a smaller still, and sometimes called the spirit run or spirit still. This is the money shot, as the distiller - by eye, nose and palate, attempts to capture mostly the "hearts", or center of the rum. The early and nasty heads and late tails are captured separately and are called the "high wines". The captured hearts are around 65%, are saved and aged in good wood (at so-called barrel strength).

Now? Now we can speak of the two intermediate "retorts" (simple pots, no neck). These are used with one goal: to eliminate the need for two stills/two runs, but to accomplish a similar result in a single run. As before the pot still/alembic delivers a vapor at about 35%. The first retort is about 2/3rd's full of water and/or low wines. The vapor from the lyne arm of the original still is guided by a copper tube to the BOTTOM of the first retort, where it then bubbles up. At first it condenses, but at a point the low wines in the first retort are heated by the vapor, and a higher alcohol (higher than 35%) escapes the first retort as output, which is similarly guided to the bottom of the second retort (which contains high wines). The output of the second retort is accordingly much higher, closer to 65% or so, and THEN is guided to the condenser, and final capture of the hearts.

Quote:
By using two retorts, the concept is to achieve a 65% in a single run.
So we basically heat again, and more alcohol jumps out, leaving more water behind at each stage, thereby concentrating the abv of the liquid. For some reason, out of the low wines tank, we don't have a retort/alembic, so much as we have a basic pipe. Question: Why not a second alembic with a similar shape?


Actually El Dorado's Morant double pot does exactly this, but the product will be less refined. The pot with two intermediate retorts is like a triple distillation, while ED's double pot distills only twice.

Quote:
I think it's confusing to call the 2nd and 3rd stages "retorts" if the retort is by definition the bendy pipe connecting the tanks (am I wrong about this?). Low wines tank, high wines tank, and mention of the additional heating stages in these might help the beginners. Just in preparing this post I'm learning things by forming these questions, which is part of why I'm doing it.


Right. It is confusing, and descriptors unfortunately get tossed around. All I can tell you is that the most common usages are the "neck" or "swan neck" for the pot still/alembic, and "retort" for the intermediate containers.

Quote:
Once we've gone through these three boil-offs (original pot, low wines, and high wines heated tanks), the first parts of the now high-proof alcohol that boil off are known as "heads" - these are undesirable, and contain lots of the crap that was infamous for making amateur moonshiners blind. These are somehow shunted out of the system (not sure precisely through which conduits in the apparatus above?).


Actually it was not the heads as much as it was the use of automobile radiators and leaded solders of cheap sheet metal that caused blindness. It is only at the end - the drip, drip liquid capture - where the heads and tails are separated out and disposed of (or recycled to the retorts or even to the original pot still/alembic). This is a good time to note that most pot stilled product still contains some heads and tails, as there is not a clear division between them. For example as the heads are diminishing, the hearts appear and are increasing: there is crossover. Not to mention that many distillers WANT some of the heads/tails in the final capture.

Quote:
Heads and heart are determined by measuring the specific gravity of the condensed high proof spirit, often observed by a floating graduated device (such as we use for our sugar tests here on the project). These SG meters are viewed through a small enclosed windowed box also known as a "spirit safe".

Once the SG increases to the point at which the start of the "heart" (the good stuff) is found, the produced liquid will now be shunted into the "keepers" tank, basically.


Exactly, but know that the same crossovers are noted, and some heads/tails will make it into the final capture, unless the distiller is willing to throw away much good output to get just the "heart of hearts" (like Barbancourt).

Right. After the heart spirit has passed through and been captured, you have another undesirable component of the alcohol known as the "tails". Heads and tails together are grouped into "feints", which can be said to be the combined undesirables of heads and tails.

Quote:
An important part of the role of distiller is choosing when to start and stop capturing the heart of the distillation. As I understand it, cutting in too early (too low a SG, too many heads included) will result in a very estery, wild beast, headache-inducer of a product - HOWEVER, the chemistry involved in aging spirit in oak barrels does a good job of taming this, which is why cuts with more heads respond well to longer aging in oak, where those heads are developed into longer chain molecules which result in some very complex and delightful flavors. Since we're talking about Jamaicans today, I'm supposing these guys are used to including about as much heads as they can possibly get away with, because as a category Jamaican rum is famous for its relatively high ester content.


Yes.

Quote:
Adding dunder to wash is analogous to what in bourbon they call the "sour mash method" - a highlypopular process in which a certain volume of leftover distiller's beer sludge aka "backset" is added to the fermentation tank to goose the fermentation or otherwise propogate the development of other flavors during the fermentation process.


Yes, again.

Quote:
Dunder is just more inherently disgusting in nature, seemingly born of a quest to figure out just exactly how gross you cold make a liquid, and then taking that to the next level Smile Whatever. Some of the world's most wonderful vegetables we must remember are grown in manure. Eat and drink up.


From garbage comes ambrosia, lol.

Quote:
1. As the distillation process goes on, the leftovers in each of the pot, low wine and high wine tanks must increasingly be made of water/larger molecules. When we say that alcohol "comes off the still" at a particular proof, doesn't that proof gradually decrease over time as the wines heat up and more water tags along to the next stage?


That's why the intermediate retorts also have drains, which can be guided to another retort, to the original still, or to waste.

Quote:
2. You mention that a portion of the low and high wines get passed back to the pot still for redistillation - what is the reason for this?


To concentrate the flavors.

Quote:
3. Why is this called "double distillation", when the liquid seems to be heated and captured 3 times?


It isn't. You could call a triple, or you could consider it a single distillation (since it is a single run).

Quote:
4. Copper is utilized as much as possible in order to remove some ugly compounds, which happen to adhere well to copper. Particularly sulfur. What I don't understand is how copper continues to work on the inside of pipes without being scrubbed clean after each pass, which by the looks of these stills isn't practical. What I mean is, sulfur reacts with copper, I get that - but then it forms an oxide layer. Surely after a still has been run for a while, that copper oxide builds up until the vapor is mostly in contact with oxide rather than fresh copper, which to my mind wouldn't react very much. How often are the internals of these pipes scrubbed/buffed such that fresh copper is exposed for sulfur absorption? I can see access holes in the tanks, are these buffed from the inside to bare copper between each run? It doesn't look practical or even possible to buff the insides of the retorts
.

It would be rare to scrub it I would think, and there is no need to be so scrupulous for the entire system, as it apparently doesn't take a large area of exposed copper to do the job. Another notion is that the copper acts a catalyst, and doesn't directly react with the sulfur, but converts it. The home distiller boyz clean with water, the end slops, etc., in a "cleaning run" from time to time. This is a very interesting question, and I'll contact Richard about this.

http://www.a-holstein.de/index.php?id=182
http://homedistiller.org/forum/viewtopic.php?f=1&t=9299

Quote:
5. What other compounds other than sulfur does copper ameliorate?


There are a bunch, but one frequently mentioned is ethyl carbamate (from fruit brandies, etc.).
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Last edited by Capn Jimbo on Wed Sep 02, 2015 12:41 pm; edited 2 times in total
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bearmark
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PostPosted: Wed Sep 02, 2015 12:26 pm    Post subject: Reply with quote

This is a fantastic discussion. Thanks to The Black Tot for taking the time to articulate the questions for all of us and, as always, thanks to the Cap'n for sharing his (idiotic) knowledge with the rest of us wannabes. Wink

I learned a lot from a brief reading of the last two posts!
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Rum References: Flor de Caña 18 (Demeraran), The Scarlet Ibis (Trinidadian), R.L. Seale 10 (Barbadian), Appleton Extra (Jamaican), Ron Abuelo 12 (Cuban), Barbancourt 5-Star (Agricole)
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Capn Jimbo
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PostPosted: Thu Sep 03, 2015 5:51 pm    Post subject: Reply with quote

Tot - addressing your question re: cleaning stills...


Per my email to Richard Seales:



Quote:
> The question was posed: "How and how often must the components be cleaned?”.

Depends. As necessary really. Good rum is VERY dependent on clean copper surfaces. A good program will have some level of cleaning after each batch distillation. We do this and periodically we pull the swan neck off, open the retorts and clean all as well as we can.

> "Is there build up of oxides of sulfur, etc.

Black copper sulphides are typical (not sulphur dioxide)

> on the copper, and if so, how and how often must it be cleaned?”.

If you see it, you clean it.

> Oh > and last "What is the proper term for the 'thumpers' (intermediate units)?

Retorts


Aha! Aha! Hope that helps...
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PostPosted: Fri Sep 04, 2015 2:18 pm    Post subject: Reply with quote

The Black Tot wrote:

Questions that remain foggy to me:

1. As the distillation process goes on, the leftovers in each of the pot, low wine and high wine tanks must increasingly be made of water/larger molecules. When we say that alcohol "comes off the still" at a particular proof, doesn't that proof gradually decrease over time as the wines heat up and more water tags along to the next stage?


During a distillation process with pot stills, the alcohol percentage does vary during the run. What is usually reported is an average of the cut or heart - the part that is taken into the spirit safe (from the 2nd or third distillation).

Quote:

4. Copper is utilized as much as possible in order to remove some ugly compounds, which happen to adhere well to copper. Particularly sulfur. What I don't understand is how copper continues to work on the inside of pipes without being scrubbed clean after each pass, which by the looks of these stills isn't practical. What I mean is, sulfur reacts with copper, I get that - but then it forms an oxide layer. Surely after a still has been run for a while, that copper oxide builds up until the vapor is mostly in contact with oxide rather than fresh copper, which to my mind wouldn't react very much. How often are the internals of these pipes scrubbed/buffed such that fresh copper is exposed for sulfur absorption? I can see access holes in the tanks, are these buffed from the inside to bare copper between each run? It doesn't look practical or even possible to buff the insides of the retorts.



Pot still distillation is a batch process, and at least from what I've seen & heard in Scotland the process calls for cleaning the stills after each batch to some degree at least

Here's a nice website where a lot of information about distillation is available.

http://whiskyscience.blogspot.fi/

And particularly about copper and sulphur...

http://whiskyscience.blogspot.fi/2014/10/copper.html
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The Black Tot
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PostPosted: Sat Sep 05, 2015 12:56 am    Post subject: Reply with quote

OK, next round! (we need a bikini-clad beauty here to parade cards around)

Firstly, some comments:

I am glad now to be clear on the retort, neck, and alembic/pot terminology.

Also, correction on the spelling of the Glengyle still provenance - Ben Whyvis, not Whevis. Sounds identical.

From the links I learned some very cool things:

Jarimi's link started with barley types which is a fascinating read. Most notably that US whiskey tends to use 6-Row (designating the number of seeds that are fertile in the seed pod) barley, which is richer in protein and lower in sugars (and as a result is often selected as cattle feed), whereas European distillers tend to prefer 2-row, which is the opposite.

The above in particular led me to remembering a remark on the Four Roses tour that all their barley is imported from Germany. Perhaps 4R is among a minority of US whiskey distilleries that is hip to the 2-Row barley?

There were also some pretty notable shifts in barley breeds in popular use prior to 1990. Things to think about when we debate whether or not to buy old malts fermented prior to '90, and what they may offer us in terms of flavors which might not be around anymore.

Great and succinct info from Mr Seale, as always. Also following the above links, I answered one of my next questions about the removal of this black residue - Exactly how much scrubbing is required? Is it a manual process? The answer seems to be that it is removable by pressure washing, and modern stills come with a custom pressure washing system that accomplishes this quickly and effectively. In addition, it is recommended to use something mildly acidic such as vinegar or lemon juice to restore maximum copper surface exposure quality while minimizing the wear on the surfaces, thereby maximizing the still equipment's longevity.

Also interesting was that copper contact is particularly critical in distillations of stone fruit mashbills, as in brandies. Ethyl Carbamate levels of these mashes are particularly high, and so if you want to know how to manage maximum copper, talk to a brandy dude.

Very cool comment on the radiators and the leaded solders, Cap'n. That's a factoid that doesn't get discussed often, and I found that very interesting. I think many people are scared of distilling their own alcohol (um, many New Zealanders...) because they think inherently that a few bad decisions on their part will result in catastrophic health effects. I almost think of it as a nice recreational safety initiative that sometime we consider linking to a good and understandable-by-the-non-chemical-engineer article about distilling safety, including the lessons of the common mistakes of the past, as above. So much good knowledge fails to make it to the public because it isn't entertainingly written. I digress. Back to distillation...

Still foggy on the wort issue - I've never seen cane juice pressed. Is cane juice ready-to-go straight out of the press for fermentation? Are its properties ideal straight out of the cane? Catch it in a vat and chuck some yeast in there and it's Miller time? Or does water get added to it to reach a desirable viscosity/chemical ideal?

Surely molasses is too thick to just have yeast chucked in and go, isn't it? There must be some water-thinning involved prior to fermentation? Otherwise you'd be doing the equivalent of boiling mud in the pot still...

(I'm not saying you have all the answers here, Jimbo. But frankly it's more fun to discuss this among friends before launching out individually into the web. Plus, if we find something we're collectively unsure about we can figure it out as a group).

"Oh, you were finished? Well then allow me to retort..."

Now that we're in agreement of what the retort actually is, let's talk more about what's really going on in there:

Alcohol vapor coming out of the pot still enters the bottom of the low wines retort, and bubbles up through it, causing some of the vapor to condense, while warming the low wines liquid.

As someone who studied community-college engineering and basic thermodynamics, I'm squinting a hairy eyeball at this, because a bubble doesn't have much time for heat transfer as it rises quickly through a liquid. Unless we're talking about a perforated base such that you get a whole host of tiny bubbles, maximizing the surface area of contact. OR if the vapor arrives by going through a descending coiled tube as in many heat-exchange systems (and indeed, similar to the condenser principle at the end here).

But even so, there's a following conceptual problem for me - Once that vapor gives up much of any heat at all, I'd imagine it's collapsing into liquid pretty fast (which may even pull a slight vacuum on the main pot, slightly lowering the boiling points there - just a side thought)...

...In order to boil off again in the low wines retort, we're going to need some additional heat, since we're now cooled down below natural boiling temperature. We didn't discuss this, but each retort must therefore be supplementally heated to excite the boil into the next stage, correct? I mentioned I saw what looked like steam jackets on the Hampden setup retorts, but on the top pic with the more tarnished still setup, it's hard to make out a retort-heating mechanism. Could you hazard a guess on what sort of heating element may be at play there? I would imagine direct flames are out, given the immense fire hazards involved (hence the viability of superheated steam).

Sticking with the top still arrangement, I don't see any valves on the return lines coming off the bottoms of the retorts (which doesn't mean they aren't there!). I'm wondering what balance of gravity/pressure forces maintain the correct level of wines in the tank required to cool the vapor from the pot, and yet not overflow up into the next retort. It doesn't look like these vessels have any sight glasses or such, so it must be self-regulating in some way.

...maybe I'm looking at it wrong, and the lower piping arrangement is a steam heat supply conduit, which is feeding the three heat zones. It's either that or the return line delivering the spent feints from the retorts to the main pot for re-distillation.

Latest theory - the lower conduits ARE steam feed, and in this system, the pipe directly off the bottom of the silver-colored condenser delivers feints back to the main pot, until the distiller decides we're getting close to the hearts, at which time the valve gets closed under the second retort, and the keeper spirit heads out of frame through the pipe to the left. But if that were the case, the heads would just pass through the system again - you'd not be rid of them as they'd be the first to boil through a second time.

Perhaps the heads go out the left as well, and are shunted somewhere else out of frame, and the direct pipe between the bottom of the condenser and the main pot is opened when the tails are reached, allowing the still to equalize its pressure to stop movement through the still as it cools? No, that can't be it, because then you'd have a closed system cooling down, which would eventually implode.

Lastly (for this episode) it would appear that the spirit safe on the Hampden setup is PRIOR to the condenser column on the far left. How can you observe specific gravity of a liquid when it's still a vapor at that point? Clearly I'm missing something there.
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Capn Jimbo
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PostPosted: Sat Sep 05, 2015 2:20 am    Post subject: Reply with quote

Tot, my now former friend, lol...


I kid, I love the Tot. Honest. And this is a great post full of keen observations and really, really good questions. This is just a placeholder to give me the time to consider them. There are others here too who are well versed in distilling and whom I suspect can even better contribute.

Nice stuff Tot. You make us think, a good thing. In the meanwhile, I defer to the homedistillation crew, whose collective knowledge and practical experience is highly valued. Tot, consider this payback, lol...

http://homedistiller.org/forum/viewtopic.php?f=16&t=6084&sid=da0637fb391f82a1c39ddc2d7eb72d76

Some basics:

First, please know that the HD crew refers to retorts in the old moonshine language, as "thumpers". The common recommendation is that a thumper should be about half the size of the main pot/alembic (and/or double the size of the expected output), based on effective heat transfer and proper operation. They do not need to be heated, but can be. There are all manner of recirculation schemes, thumper "tuning", using different fill schemes (water, low wines, high wines) et al. No matter, at the end the distillate is collected and (mostly) hearts retained.

If you want to get up to speed on practical theory and dynamics of retort/thumpers:

http://homedistiller.org/equip/designs/thumper

More later...
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The Black Tot
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PostPosted: Sat Sep 05, 2015 5:13 am    Post subject: Reply with quote

I've just started skimming those pages on the home distillers' forum.

Let me take some time with this today, I think I'm closer to getting it and I should be able to put it into plainspeak.

I just need to stare at it some more and read people talking about it until one of them says it in a way that clicks for me.

Stay tuned.
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PostPosted: Sat Sep 05, 2015 8:53 am    Post subject: Reply with quote

Tot...thanks much and I personally look forward to your informed understanding. Thanks for your efforts. A great thread...
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PostPosted: Sun Sep 06, 2015 1:23 am    Post subject: Reply with quote

OK, I've got it. Here goes...

How a retort does its thang

Firstly, we must understand how the internals of a retort are roughly constructed.

While there are many variations on how to accomplish this well, the very basic principle is that the output of the primary pot (or the previous retort if we're talking about the 2nd retort in a system) enters through the top of the retort through some form of pipe which, indeed, as the cap'n explained it, expels the vapor near the bottom of the retort tank.

My skepticism about heat transfer was based on a visualization model that many of you might also be stuck on, that of bubbles of AIR rising through a liquid. Since air on this planet is going to be gaseous at all temperature ranges we will experience or create without some pretty serious Kelvin-capable refrigeration, we think of air bubbles as things that, apart from some springy fluctuations in their volume due to air's springy compressability, don't altogether collapse as they pass up through a liquid.

Distilled alcohol vapor off of a pot still is not like air. It is more like steam - it is a very physically volatile gas which, if cooled even slightly, will entirely collapse in on itself, becoming liquid again.

Originally I stated that bubbling hot vapor coming out the bottom of a pipe in a retort wouldn't have enough time to give off its heat by the time the bubbles reach the surface of the liquid within the retort.

In fact, the vapor does indeed collapse prior to reaching the surface, and in doing so, the alcohol vapor (along with the water that came along with it [remember we are dealing with low wine 30% type ABV here]) mixes in with the liquid in the retort tank, and this change of state throws off heat energy into the liquid itself, warming it.

As such, bubbles of low wine vapor come INTO the bottom of the tank, but no bubbles actually reach the surface of the liquid in the tank. They collapse before they can get there. More on this later.

I was in fact onto SOMETHING though (insert blind squirrel/nut imagery here), in the sense that this process is in fact aided by a piping system which organizes the vapor such that it enters the bottom of the retort liquid reservoir in small bubbles, preferably scattered as evenly as possible around the base of the tank, encouraging the most effective heat transfer and therefore successful bubble collapse, avoiding any larger bubble which may survive its journey to the top of the liquid.

Fun fact: at this point, incidentally, we arrive at why the home distillers have the nickname for the retort of "thumper", since the collapse of the vapor bubble is violent and percussive, similar to water-hammer sounds in old radiators, and when a home still is cruising apparently the frequency of this popping sound is at a sort of "drum solo rate".

So...we've got the pot still output dissolving itself successfully into the retort tank liquid. NOW what?

As we were told earlier, the liquid is warmed by the release of heat from the vapor of the previous stage, and this leads eventually to a boiling condition in the retort...

...WAIT... this is where I stopped you before - How, I asked, after the vapor had already given off heat, and was now cooled below its boiling temperature, could you bring a second vessel to a boil, without adding more heat energy in the form of an external heat source?

The answer is quite cool, and has to do with two principles that work well together.

Firstly, the act of pushing vapor down through a column of liquid to its bottom involves pushing against the head pressure of the liquid in that tank...

...SO - the pot still is working against this pressure to force vapors out of it. This means the pot still's boiling environment is slightly PRESSURIZED. From the science labs of our marvelous and much-appreciated publicly-funded pre-1990 educations we know that when a vessel is pressurized, things boil at a higher temperature (and vice versa).

Therefore, the pressurized vapor coming out of the pot still is in a sense superheated relative to the amount of temperature required to boil the liquid in the slightly-lower-pressure next chamber, the retort.

This would be enough surplus energy to boil the second chamber on it's own. However, it is also true that the liquid in the retort is by nature, higher in alcohol content than in the previous stage*, meaning it ALSO has a lower boiling temperature to begin with. So it can still lose heat but nonetheless retain more than enough for the lowered boiling requirements of the next stage.

*at this time it probably bears mention that retorts are often "Charged" (pre-loaded) with tails from a previous batch. This is not necessary, but if you have water in there, you're wasting your time, since the alcohol that you just boiled out of the water in the pot still will now just be re-combining with water in the retort - pointless. So this is part of the role of feints in the distillation process - as charging liquids in the retorts, with high enough abv to bond with the water contained in the vapor from the previous stage, and hold it back, rather than holding back the alcohol.

This is another important conceptual/perceptual trick here. Don't think of distillation so much as alcohol moving out of the liquids and bringing some water with it, so much as THE REMAINING LIQUID HOLDING BACK THE WATER FROM CONTINUING DOWN THE CHAIN. This will help you understand the process a little better. The tail feints charge, because it was tails, has a higher boiling point than the hearts we're after. So, as the vapor from the previous stage enters a retort and collapses into solution with the liquid, the feints charge could be said to grab the water out of the distillate into solution and hold on to it, allowing the lower boiling point hearts to prepare to flash off when the liquid reaches that temperature first. I have found this conceptual flip to be helpful.

OK, where were we...all right.

We must also consider other things that are going on thermodynamic-ally at this time. The retort tank is also radiating some of its heat to the surrounding environment. This lost energy will come into play later in the explanation.

The next step in confusing newbies like me is "OK, so the previous stage boils the liquid in the next stage with no added supplemental heat - how is the correct level of the liquid maintained?"

...and for this, there are again several horses for courses.

We've talked about the ideal, where vapor bubbles never reach the surface, and the liquid gets hot enough that it boils its own higher abv vapor off into the next retort (or condenser if it's the final stage).

What can go wrong? Essentially, three conditions are undesirable:

1. The retort's liquid is so cold (for example at still startup) or the retort's surface area is so large that the resulting heat losses tax the heat gains too much (or even exceed them - such as distilling in an outdoor still on a crazy cold day) to the point that the liquid builds up to the point of overflowing out of the retort. Result - no distillation.

2. The retort's liquid is heated up so much that the liquid has no cooling effect on the incoming superheated vapor, and the vapor bubbles DO succeed in passing up through the liquid to the surface. In this case, you ALSO get reduced distillation, since you're just passing the previous stage's ABV vapor through with all of its water tagging along with it. No bubble collapse, no water stripping, and, worst of all, your higher-boiling-point tails are probably also launching out of the liquid and going along with your hearts through the system. No gooda.

3. The pot still is overheated to the point at which the wash foams up and boils over. The home distillers amusing refer to this as the still "puking", passing undesirable solids from the wash into the next stage that weren't supposed to go there.

OK, now that we know what we DON'T want, how are these effects managed/maintained?

#1 is avoided by either having a runoff pipe in the retort, such that if liquid rises above a certain level, it will spill into a return pipe that sends the excess back to the pot still. THIS is likely what those pipes coming off the bottom of the retorts in the top picture are about. Note there will be some form of vapor lock trap such that distillate vapor doesn't get down these pipes, only overflowing liquid.

It is also avoided at still start up by pre-heating the retort charges. If you have a fancy still such as the Hampden people appear to with steam jackets around the retorts, this is an option for you. Presumably cooler (but still basically hot, I just mean slightly below the retort liquid's boiling points) water could also be run through those to hold temps in the preferred zones for ideal operation.

It is most crudely and probably in the early days avoided purely by designing the retorts with surface areas and materials with the right amount of heat conductivity to perfectly throw off the right amount of heat to keep everything perfectly in balance in ideal operation. This would also necessarily involve knowing what the suitable outdoor atmospheric conditions were to achieve this balance.

Note that a retort when running properly at temperature is passing almost exactly as much material out of it as it is taking in. While water is being added to the tails charge from the previous stage, an increased amount of alcohol is also passing out the top. So the system can exhibit a rather elegant balance when things are as they should be.

#2 is prevented by either reducing the heat source on the pot still such that the rate of heat entering the retort comes back into balance with the retort's ability to throw it off radiantly, providing some additional cooling measures as may be possible at Hampden, or again, revisiting still design, increasing the size of retorts for your desired pot still boil rate.

#3 is also prevented by not overheating the pot still, but is mitigated in home distilling by what is known as a "slobber box", which is in effect a container similar to a retort, only with no liquid in it, and no pipe carrying vapor to the bottom. Vapor comes in the top at one side and goes out the top at the other side. If any crap is spit out of the pot, it falls by gravity and is collected in the tank, and does not pass on to further retorts/stages.

Other fun facts:

-Infusion of flavors is popular in home distilling by adding things such as macerated fruits or flavorings in the charge of the final retorts.

-Home distillers running small stills without the benefit of fancy spirit safes etc make their cuts by collecting their still's outputs in various sized smallish jugs, consecutively. In this way they can figure out post-distillation and at their leisure by taste, hydrometer, or rubbing between fingers to determine consistency in which jug the heads, hearts, and tails became acceptable or unacceptable. They then blend the heart jugs and save the tails for future retort charges.

-Running the still slowly results in the cleanest separation of heads, hearts and tails. Of course, slowly on a larger still is going to result in a larger and distillery-suitable flow rate than Jebediah's hillside or garage contraption.

-Running the still too fast will result in "smearing", which is where the heads, heart, and tails all come out mingled together, impossible to separate, and tasting very bad. Not such an issue if you're going to distill a second time slowly, but if you're using a retort system, the whole point of the system is to only have to do a single run, with greater efficiency vs. having to heat everything twice and run the condenser harder at the end to grab what is a hotter liquid straight off the first pot distillation vs the stepped down lowered boiling temperature coming off the 2nd retort.

-If you're having to use a slobber box, you're probably not distilling slowly and carefully enough to get a clean hearts cut.

And that, my good men, is how retorts work in traditional Caribbean rum production!

Still don't know jack about fermentation properties...
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Nomad
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PostPosted: Sun Sep 06, 2015 3:01 am    Post subject: Reply with quote

BRAVO! It's always a good day when you learn something and that was a wealth of information delivered in layman's terms. Well done.
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PostPosted: Sun Sep 06, 2015 3:48 am    Post subject: Reply with quote

Mercy, mercy!


A tour de force, thanks for taking the considerable time to consider and to pass along what you learned. If I may be so bold - since much of what you related is rather technical in nature, do you think you might rewrite your findings and understanding in terms a Compleat Idiot might more completely understand. Here's my two cents:

    1. The most common classic rum setup involves two retorts or thumpers

    2. The objective is to accomplish in a single run what would require two runs/batches in a pot still alone.

    3. Many pot stillers do not bother with the added complexity of the retorts, and simply do two runs in a basic/classic pot still/alembic.

    4. Others rely on the vast experience of the other small and home distillers by using a retort/thumper that is about one-half the size of the main pot still's capacity and/or twice the expected ultimate output of the still. These distillers use a basic system, with minimal piping, will not heat them, and will charge them with either water, low wines or high wines.

    These systems are often home-built, and surprise! They work quite well, less by understanding the dynamics but more by simple experience and using their own senses plus/minus a parrot (to test output alcohol percentage). Some use one thumper, some use two.

    5. A very few well heeled craft distillers will purchase and use a sophisticated, piped, metered, automatic cleaning and VERY expensive complex ystem by say Holstein or Carl. These require time, expense and training plus the unintended consequence of too many adjustments. It is not clear their output is superior to the even the simplest standard pot still/alembic with worm condenser.


My idiotic summary...

...would go something like this: the vapor from the main pot still/alembic - at around 30% - is guided to the precharged retort/thumper and bubbles up. In the process it is redistilled and the percentage alcohol is increased, and either passed to a second charged retort, and/or to the condenser where the anxious distiller awaits: smelling, feeling, tasting and occasionally testing percentage (with a parrot) - where he/she attempts to collect mostly hearts at about 60%.

Most of us could learn to build and run a simple pot still.

Whether a simple pot still, single or double retort is/are used, the end point is the same. The distiller will be closely monitoring temps (especially coming out of the heated pot still), and observing the output. If he likes the output, he may increase the heat under the pot (speeding up the run); if he doesn't, the heat may be reduced to allow better distillation and to slow the process. This is called power management and simply means adjusting the heat under the pot still/alembic.

What finally comes out of the condenser, in order: a bit of foreshots (methanol, discarded), heads (recyled), hearts (seconds are late hearts), and tails (recycled). Even so, there is some crossover, ie some heads and tails will be captured with the hearts. How much is up to the distiller, but he/she is after the hearts. Some distillers like a bit of the heads or tails to be kept.


An example of a pot stilled cognac using two pot still/alembic runs:

Quote:
First run power management with wash at 8.5%
Foreshots discarded
Heads are taken @ 40 litres / hour (slow, low heat)
Hearts are taken @ 117 litres / hour and (medium heat and speed) and are kept for 2nd run
Tails are taken @ 150 litres / hour (high speed).


Second run with wash from first run at 28% (plus low wines from 1st run and seconds from 2nd)
Foreshots are discarded
Heads are taken @ 50 litres / hour
Cognac is taken @ 117 litres / hour (this is premium quality hearts)
Seconds are taken @ 36.6 litres / hour (this is lower quality hearts intended for re-blending into subsequent boiler charges)
Tails are taken @ 150 litres / hour

All heads and tails from multiple runs are blended as feints to be added to wash for subsequent 1st runs.
1st run is typically 90% wash & 10% feints
2nd run is typically 75% low wines (from 1st run) and 25% seconds (from previous 2nd run)

http://www.artisan-distiller.net/phpBB3/viewtopic.php?f=59&t=7639

Note: it is important to note that most pot stilled rum contain some of the heads and tails, as these cannot be effectively or economically separated out. In fact, those heads and tails is what gives pot stilled spirits their notable character.
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PostPosted: Sun Sep 06, 2015 4:53 am    Post subject: Reply with quote

Thanks, guys.

Basically, I started asking these questions because I got tired of looking at pictures of the equipment and not being able to come up with a fact-based conclusion on what pipes were going where and why.

That's why I needed to go into this detail. I have to know the physics of this stuff. I studied marine engineering in college to work in the engine rooms of ships - I'm not happy seeing pipes whose role I can't place in a system Smile

You really started it cap'n when you posted those pics of the stills and left me in the dust with your explanation! Haha.

It's been a great few days of moving forward, understanding-wise.

I feel like I might like to take this further forward somehow/someday on the Project to an analysis of specific famous stills, and what's unique about them technically, but I know that info is harder to come by than what we've done here this week.

I'm concerned (as are we all) about things like the potential decommissioning of DDL's Versailles still. I'm annoyed that I don't know much about what makes the statement stills tick and why they are unique, since I love what has come out of them so much.
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