single distillation whiskey vs. multiple distillations

[nick jones]

OK, a hybrid pot still is a pot with a column on top or on the side of it. They are designed to make product in a single pass...

Carl makes hybrid stills, and they do not design them to make product in a single pass. They will train you in double distillation, and demonstrate why it is superior to single pass. Some of their competitors tout single pass as a perk of hybrid stills, but the fact is that single pass takes more time and energy than double distillation, and therefore makes little to no sense (unless you are one of those people who, for some reason, thinks that there is some difference in the flavor).

Nick

[HedgeBird]

I'm definitely throwing in with Bluestar here. I'll never understand the source of the common misconception that the volume of a still is proportional to the length of time required to run a batch through it; there is no correlation between these two factors at all, either theoretically or in practice.

Your right that you can't determine run time based on charge size, as its just one factor. But at the risk of being nit-picky. All other factors being the same, a batch that is 500 gallons is going to take longer to distill than one that is 250 gallons, so still charge size and run time are correlated. There is a relation between the two beyond chance, hence correlation.

[nick jones]

...All other factors being the same, a batch that is 500 gallons is going to take longer to distill than one that is 250 gallons, so still charge size and run time are correlated...

Hedge,

Am I correct to understand your meaning of "all other things being equal" to be that, for example, in scaling up from an air-cooled, sterno can heated, 0.2 liter desktop still to a 250 hectoliter still, one would use the same heat source and condenser? If that is your meaning, than I guess you could look at volume as having a bearing on distillation time. However, this hypothetical situation is a bit nonsensical, and not the common misconception to which I was referring.

Any still, from 0.2 liters to 250 hectoliters, has the potential to finish a batch just as quickly as any other still, given appropriate design considerations. A surprising number of people seem to think that this is not the case, and I am attempting (somewhat unsuccessfully, apparently) to dispel that misconception.

Nick

[Roger]

Would it be safe to say that once any given still is finally up to sufficent temperature to begin off-gassing of vapor, and if there were sufficent heat to maintain said constant temperature, and a likewise adequate condensor to accept and process all appropriate vapor, that the time to complete any given batch at like ABV would be constant regardless of volume ?

However many things would affect the still getting to that initial temperature such as design, insulation, surface area of heat transfer medium vs entire liquid volume, etc ..

[nick jones]

Would it be safe to say that once any given still is finally up to sufficent temperature to begin off-gassing of vapor, and if there were sufficent heat to maintain said constant temperature, and a likewise adequate condensor to accept and process all appropriate vapor, that the time to complete any given batch at like ABV would be constant regardless of volume ?

Almost.

An addition of heat to your still will get you one of two results: a change in temperature or a change in phase (phase change meaning change from liquid to vapor.)

Adding heat is necessary to bring the temperature up to boiling, but once the boiling point is reached, additional heat is required to vaporize your mash (more than the amount of heat needed "to maintain said constant temperature.") This amount of heat was, once upon a time, called the latent heat of vaporization (they've got some fancy new term for it these days). Interestingly, the reverse of this process is the basis for evaporative coolers and mechanical refrigeration (a vaporizing liquid sucks heat out of a surrounding medium).

Therefore, once the boiling point is reached, the quantity of vapor produced is proportional to the quantity of heat exchanged with the boiling mash (more heat = more vapor).

That being said, because it takes substantially more heat exchanging potential to heat up a given volume of mash in a reasonable amount of time than it does to change the phase of this mash to a vapor, it would need to be a very poorly designed still (i.e. a heat-up period measured in hours rather than minutes) where the limiting factor of the distillation was the amount of heat required to vaporize the mash. Also, due to the inverse proportion between the ABV and the latent heat of vaporization, this limiting factor is only reached toward the end of a distillation anyway.

Other limiting factors that you may also want to consider besides ABV, heat up time, and condenser size are foaming, surface area to volume ratio of the pot, restriction of vapor flow prior to condenser, and reflux ratio.

Nick

[HedgeBird]

Am I correct to understand your meaning of "all other things being equal" to be that, for example, in scaling up from an air-cooled, sterno can heated, 0.2 liter desktop still to a 250 hectoliter still, one would use the same heat source and condenser? If that is your meaning, than I guess you could look at volume as having a bearing on distillation time. However, this hypothetical situation is a bit nonsensical, and not the common misconception to which I was referring.

no, I did not mean scaling up from one still to another, but rather if all factors are the same except batch size, the larger batch is going to take longer.. So for example if I load my 150 gallon capacity still with 75 gallons of wash (and run it as fast as my heat source and cooling system allow) its going to take longer to strip that batch than if I loaded it with a full 150 gallons.

Any still, from 0.2 liters to 250 hectoliters, has the potential to finish a batch just as quickly as any other still, given appropriate design considerations. A surprising number of people seem to think that this is not the case, and I am attempting (somewhat unsuccessfully, apparently) to dispel that misconception.

I really was/am nit-picking a bit with my argument, and agree with the point you are making; that larger stills don't necessarily take longer to run. But I would think thats not because batch size and time are not correlated, but rather because they typically have larger heat sources, more surface area for evaporation and larger condensers.. right?

[nick jones]

no, I did not mean scaling up from one still to another, but rather if all factors are the same except batch size, the larger batch is going to take longer.. So for example if I load my 150 gallon capacity still with 75 gallons of wash (and run it as fast as my heat source and cooling system allow) its going to take longer to strip that batch than if I loaded it with a full 150 gallons.

I think that I see what you're getting at, (although I believe that you meant to say that 75 gallons would take LESS time than the full 150). It is perhaps a bit nit-picky, but I'm all about nit-picky, so no worries.

It is true that all other things being equal, a greater number of proof-gallons (if you'll permit me to nit-pick a little too) of wash in a given still (or two otherwise identical stills with different net volumes) will take a greater amount of time to distill than a lesser number of proof-gallons.

...larger stills don't necessarily take longer to run. But I would think thats not because batch size and time are not correlated, but rather because they typically have larger heat sources, more surface area for evaporation and larger condensers.. right?

Absolutely right. I guess that for me this would be the difference between saying "the volume of a still" and "the volume of mash". When I speak of a larger volume still, I'm assuming an appropriately scaled up still. Perhaps this is where I get confused with what other people are talking about: when they say "larger still" they assume that only the net volume increases. My guess: a deficiency of whiskey drinking (single, double, continuous, whatever) is causing the communication problem .

Nick

[bluestar]

How did the results differ from single distillation in hybrid vs. double distillation in pot still?

It is hard for us to keep hybrid distillation from our current mash down below 160 proof for the entire heart run, although we could always further dilute the mash to achieve that. Also, we do get a more refined flavor from our double distillation IF we do a shallow tail cut on the first distillation. But more importantly, we think we get a better yield (hearts ratio) at equivalent flavor.

[fldme]

What is your beer gallonage.

[bluestar]

What is your beer gallonage.

60

[fldme]

I would expect that with say 30 gallon beer, but not 60. You are figuring 60 gallons of liquid to a bushel of grain. With malt counted as 53 pounds to the bushel instead of 35?

[bluestar]

I would expect that with say 30 gallon beer, but not 60. You are figuring 60 gallons of liquid to a bushel of grain. With malt counted as 53 pounds to the bushel instead of 35?

Again, lets make sure we are using the same vocabulary. You said beer and mash are the same to you. I am 60 gallons mash, which has about 115 pounds of grain and flour and whatever water needed to bring to 60 gallons (about 45 gallons or so). We are in the 10-12% alcohol range when we are done fermenting.

I notice that some of your contributions make a lot of assumptions about the production that might be typical for your experience, but are different than what many of the other small craft distilleries may be doing.

[fldme]

Beer gallonage in the American distilling industry or the big boys as some call it, is a term used to say how many gallons of water and stillage to a bushel of grain. I did the calculation based on 53 pounds as a bushel. Even though a bushel of malt is 35, it is counted as 53. This does not take into consideration the variation of pounds to the bushel of grain. For instance good corn is 53 or 52 pounds to the bushel. Real good corn in a good year is 60 pounds to a bushel. So with that said, you are running roughly a 27.6 gallon beer. So you should be running off the top of my head about 12-14 percent mash. Which is thick, but will work in a pot still real good. On a continuous, you would be over 160 proof easy. I use terms that are industry standard or the big distillers, they have it right, and I feel small distillers should take everything they do into consideration. After all, the KY bourbon industry has been around a long time, so they must be doing something right.

[Dehner Distillery]

I run mine with a single pass. Four plate refraction head with dephlegmator.

For me energy wise it is cheaper, speed wise it's faster than distilling it twice.

Take care!

[nabtastic]

The "big boys" are not about flavor or quality or any of that. they are about money - whatever the most efficient route is, that is the route they are taking. I'm not sure why we are idolizing the bourbon trail distilleries. The people that actually run the stills are chemical engineers (not that there is anything wrong with that) but they have a job to do. that job is to take the cheapest grain and (with the highest yield) make the best of it. idk where the beer gallonage talk is coming from since I'm not familiar with it.

IMO single v double is a function of yield, not quality. the big distilleries in KY primarily make bourbon. Bourbon has a max distillation proof. Running the beer through a stripping still (continuous column) allows them to get closest to that proof continuously. unless grains/mash are added back to the pot still after the stripping still, I don't see how the final distillation would benefit. On a batch run, the beer run allows you to distill fast collecting multiple batches, followed by a hearts run to remove the less desirables.

I believe that ultimately it is the still that you use and the yield in your mash that determines if you should do a single v double (etc) distillation.. my 0.02.

[fldme]

Have you ever toured a large distillery or do you kow any of the actual people running those plants? Obviously not because what you are saying is far from true. There is more craft in lets say four roses for instance than most micros operating today. They use high quality grain, use old techniques such as using lactic bacteria to sour their yeast mashes, cultivate their own yeast, use tradional stills and aging procedures etc. Yes bourbon has a max distillation proof. 160. Not one plant making bourbon today I know of runs over 140. Still proof is higher than it used to be, but I know nobody running over 140. What makes you think they use continuous stripping stills to get as close as they can to 160? A continuous beer still can produce flavorful spirit as low as 100 proof. Yes, there are chemical engineers working in the big plants, so what, they have a degree. But in most plants you have generations of families often times desendants of the original founders as is the case with the Beam family at their families namesake distilleries. And they are not all there just for show. Most of the micro distillers think ill of the big guys. This is a bad thing. Get to know some of the people running these plants, they are all friendly and guess what, most are supportive of the small distillery movement, but are concerned about the quality of the products being turned out. And most will. Be glad to help you figure anything out trouble wise out might run into. I may be wrong, but from your post above, you have no idea what you are talking about. And one should never criticize what they do not know.

[Dan P.]

Double distillation is necessary if one is using a pot-still and ordinary grain mash of between 6-8% abv.

[nabtastic]

i assume that was about me, and yes i have toured most of the big ones. and most of them are "nice" with a few key exceptions. most of the products churned out are shit though. and that includes a lot of little guys too. that being said, they do make a lot of good products too, just typically not very experimental or challenging.

Dan, there are wild variations in pot still designs. Too make a blanket ruling on the use of all pot stills is concerning. If it's a traditional scotch or irish still, then sure - but pot stills have had a lot of improvements to them.

NAB

[nabtastic]

I should also note that when I refer to the "big boys" I'm not necessarily talking about the bourbon trail - though in some cases thats true. I'm more specifically referring to MGP Ingredients, Ultra, EMCO, and what not.

Sorry, I get defensive when I'm hungry. I'm gonna go grab a snickers.

NAB

[Dan P.]

Dan, there are wild variations in pot still designs. Too make a blanket ruling on the use of all pot stills is concerning. If it's a traditional scotch or irish still, then sure - but pot stills have had a lot of improvements to them.

NAB

I believe "pot still" is actually a fairly limited definition. The only improvements that you can make to a pot still is some sort of "dephlegmator", known colloquially as a "purifier", or "lentille" or similar, or a thumper/s. I'm not ware of any pot still that goes beyond those innovations and is still accepted as a pot still, and even then I would think that you would qualify a pot still as having a purifier, or whatever, when talking shop. I do not have any emotional investment here, it's just a matter of semantics, and I'm sure many might disagree.

But anyway, without any sort of active reflux or doubler/thumper, you are getting maybe 25% singlings from an "ordinary" grain wash, and with you will get maybe 40%? Neither of those are really ideal as a final %ABV. Maybe if you made a big sacrifice to the tails cut, you might be able to get a decent ABV in the early hearts, or if you had a string of thumpers (as in some traditional rum distillation)? But on a pot still (a "pot still" pot still, that is), I don't think you are going to get anywhere with a single run without an unacceptable level of inefficiency.

[nabtastic]

Dan,

That's fair. What I mean by variations is that an alembic still, a traditional Irish still, a hybrid column (which I suppose is a sort of dephlegmator), and there was a distiller in Indianapolis I believe that had a very, very unique still that I can pretty much only label a pot still. That's all I'm saying. I've only used an alembic pot still, so that's all I can speak for.

I'm with you though; semantics can often get difficult online.

All the Best

NAB

[bluestar]

Double distillation is necessary if one is using a pot-still and ordinary grain mash of between 6-8% abv.

Depends on the geometry. We have a pot still, and with a dephlegmator and going in with our grain mash of about 10% abv, we can come out at sufficient strength for whiskey. But we don't, we use it for low wines, because the quality of the product needs further distillation to get the separation we want on the congeners. I think fldme is correct that a well designed industrial continuous still can produce a greater degree of separation on congeners with a lower output proof than one would expect doing a double distillation on a pot still. Sort of. I have never tried, but I guess you could dilute the low wines all the way back to 10% and run again to get a lower proof output with good separation on the congeners?

But I still feel like we are comparing apples to oranges: you don't get the same whiskey, and there is value in having different methods for production to give different products. JMO.

[Devious]

How are you running your column/pot hybrid? I run 4 - 55 gallon column/pot hybrids with four plates. I have independent cooling control on both the dephlegmator and condenser. I do one pass on everything I make, whiskey, rum, vodka, and gin. The key that I have found is deciding what proof you want to pull at. This will dictate your initial flavor profile. There are two ways to effect the proof, heat source and cooling water. So for example, my bourbon. I bring the pot up to temp, dephlegmator is shut off and condenser is wide open (always wide open), heads proof is about 120. This allows most of the heads to leave the still without getting caught up on the plates. When I decide that heads are done I open upen up the cooling water to dephlegmator just a touch. This should bring the proof up to 130 and that is where I keep it for the entire run. I do this by periodically increasing cooling water flow to dephlegmator. Toward the end of the run the dephlegmator will be wide open and my proof will start dropping so I decrease the heat on the still periodically to keep my proof at 130. When distillate is just barely dripping from the line I start my tails by turning the heat back up and shutting off the dephlegmator. 55 gallons takes 6 hours. Depending on mash alc content yield is approximately 8 gallons at 130 proof. The flavor has always been far stronger (corn) and more complex than our pot still (stripping/spirit run) experiments. I like the stronger flavors it allows for more interesting things to happen in the barrel. As a side note my plates are never bubbling at this proof. They don't start to fill until I get over 150 proof.

I'm just curious how others run their pot/column hybrid still. I think there are many ways to do so which could have an impact on this discussion.

Thanks for all the info. I have been discussing this with other distillers for quite a while and experimenting with it and the pot/column hybrid SEEMS more efficient (time wise and total distillate collected), is more versatile, and yields a more complex product than a pot still (in my experience).

[nabtastic]

Devious - so is that a single hearts run through your column? I sure would love to have a dephleg on my pot...

I think the bulk of the OP's questions can only be answered on a still-by-still basis. IMHO distillation has far too many variables to ask if one option is always greater than the other..

[Devious]

Devious - so is that a single hearts run through your column? I sure would love to have a dephleg on my pot...

I think the bulk of the OP's questions can only be answered on a still-by-still basis. IMHO distillation has far too many variables to ask if one option is always greater than the other..

Yes, it is a single hearts run. I agree, far too many variables.