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distillate temperature


hawk

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Water will be precious at our distillery -- we're going to try to recapture and re-use, but we know we'll still use a lot from our low-production well.

One variable on water use would be the output temperature of our distillate (not the condensing water -- we know that will be hot), but we've heard conflicting things. One expert tells us to stay below 25 C (77 F) or else we'll start to degrade quality. Another said that just wastes cooling water, and as long as we stay below alcohol vapor temperatures, we'll be fine.

I'm skeptical of the latter -- even if we're not at overall vapor point, higher temperatures have to accelerate evaporation, though I suppose we could try to capture that with a container lid.

So the real question here is just what about heat damages our distillate (i.e., "how") and what temperatures matter how much. And the p.s. to this is to add that since we're starting with hard cider, we're concerned about aroma and flavor characteristics and not just the alcohol itself.

Thanks,

Hawk Pingree

San Juan Island Distillery

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I'm not quite sure I understand what you're talking about, but I'll see if I can explain what I'm reading.

You said someone said heat will damage distillate? That's ridiculous, how do you think the distillate becomes distillate, it gets heated into a vapor. The reasons for keeping the distillate at a consistent temperature is for more accurate readings of your alcoholometer, that is without doing a compensation calculation. You actually want the distillate to come out warm to hot-ish as it will flash off some bad stuff, a little, as it sits and cools.

For cooling water just have it coming out warm to hot-ish. Usually I teach people to have it below 150F. As long as all the vapor is getting knocked down your good on cooling water exit temp. You can hold a mirror to one of the exit ports on your still, where the distillate is coming out and see if it fogs up; that way you'll know if you still vapor coming out.

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The kind of still you are running might determine the answer to this question. If you are pushing cooling water from the final condenser to a partial condenser in a short column for rectification, the temperature of the water will have a major impact on your distillate.

Many stills are designed this way. If it's alambic with no helmet condenser the temp will simply be a matter of fully condensing your final spirit.

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The kind of still you are running might determine the answer to this question. If you are pushing cooling water from the final condenser to a partial condenser in a short column for rectification, the temperature of the water will have a major impact on your distillate.

Many stills are designed this way. If it's alambic with no helmet condenser the temp will simply be a matter of fully condensing your final spirit.

I think this might apply to us. We have ordered an Adrian still with 4 plates in a side column, and it looks like there's a pre-condenser at the top of that column.

So how does pushing cooling water there have an impact on the distillate? Or I guess I mean "how" and "what kind of impact?"

Thanks for helping.

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  • 4 weeks later...

For Alembics the quality of spirit has everything to do with condenser output temp/spirit output temp. The temp that you run your condenser should be determined based on what your trying to make, how long you intend to age it, and if it is fruit or grapes what varietal your are distilling. This is very very important because there is a reduced solubility of volatile fatty acid esters at low temperatures, and small temp changes can affect the aromatic profile quite considerably.

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I know of one small distiller in an arid environment who uses groundwater and captured rainwater, as well as recycling his water as much as he can. He does not, to the best of my knowledge, do anything unusual in his actual processes in order to conserve water. One common consideration in whiskey-making is mash thickness. A thin mash can be easier to work with in many ways but a thick mash conserves both water and energy.

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I've done some experimentation on this and have a view on condenser temp based on that experience but I've not seen much in reference material on the subject. Any reccomendations for access to hard data on solubility of esters and temperature?

Thanks,

Ken

For Alembics the quality of spirit has everything to do with condenser output temp/spirit output temp. The temp that you run your condenser should be determined based on what your trying to make, how long you intend to age it, and if it is fruit or grapes what varietal your are distilling. This is very very important because there is a reduced solubility of volatile fatty acid esters at low temperatures, and small temp changes can affect the aromatic profile quite considerably.

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I've done some experimentation on this and have a view on condenser temp based on that experience but I've not seen much in reference material on the subject. Any reccomendations for access to hard data on solubility of esters and temperature?

Thanks,

Ken

Ken,

here are some books I recommend.

Le Cognac, Sa Distillation. by :Lafon;Couillaud;Gaybellile editions J.B. Bailliere In 1954 it would have been known as Notes sur la Distillation dans les Charentes. By 1958, the above name had stuck.

Lafon also wrote a book in 1910 called La Distillation dans les Charentes

The french books are greatly under utilized and are a great resource you will not find these in English but if you do please let me know :)

Whisky by Inge Russell talks about it a little but really doesn't go into detail about why the number is what it is in Scotch. I think this is due to the fact that Scotch distilleries often only make one style of spirit and so they want to make the same thing every batch unlike fruit spirit that can be quite different from season to season and varietal to varietal but that is just a guess.

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Throughout, it must be emphasized that an adequate supply of cold water to the condensers or worm tubs must be maintained. Inadequate cooling will result in a spirit being collected at temperatures greater than 20ºC, which adversely affects the congener balance, allowing higher concentrations of compounds usually associated with the feints to distil over with the spirit. This is also true of forced or rapid distillations.

As a beginner, it has been useful to understand the chemistry of batch distillation, eg. how the demisting test works. I am not sure this is even in reference to your question.

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As a beginner, it has been useful to understand the chemistry of batch distillation, eg. how the demisting test works. I am not sure this is even in reference to your question.

Personally I don't use demisting. But if I remember correctly and anybody chime if i have this wrong or that has a book handy the mixture becomes cloudy/milky/tubid because of fatty acids and esters coming out of suspension with your water addition.

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The higher the temperature of the cooling water, the more volatiles will evaporate from the distillate once it leaves the still.

Higher outlet temperatures may be desired (to let the volatiles evaporate) but then the product cannot be nosed as the volatiles mask more subtle aromas.

Lower water temperatures allow volatiles to be contained in the end product (which sometimes, but not often, might be desirable) but allows "in-line" nosing to identify different fractions from a pot still.

A general rule of thumb I use:

When stripping - run fast boil and a hot distillate/hot cooling water out

When rectifying - run a SLOW boil and low temperature distillate.

I agree with Copperstill on the "cloudiness" - it is the result of water insoluble oils emulsifying when water is diluting the alcohol (in which the oils were soluble).

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The higher the temperature of the cooling water, the more volatiles will evaporate from the distillate once it leaves the still.

Higher outlet temperatures may be desired (to let the volatiles evaporate) but then the product cannot be nosed as the volatiles mask more subtle aromas.

Lower water temperatures allow volatiles to be contained in the end product (which sometimes, but not often, might be desirable) but allows "in-line" nosing to identify different fractions from a pot still.

A general rule of thumb I use:

When stripping - run fast boil and a hot distillate/hot cooling water out

When rectifying - run a SLOW boil and low temperature distillate.

I agree with Copperstill on the "cloudiness" - it is the result of water insoluble oils emulsifying when water is diluting the alcohol (in which the oils were soluble).

Again coolant output temp and spirit output temp depend on many factors the rule of thumb your describing is only one way. I am curious are you using a shell and tube condenser or a worm?. I know production houses keep the coolant temp the same for both runs. I know of production houses that run lower coolant temp for wash and higher output temp for spirit. Coolant temp output is just one element and is independent of heat input in that both effect the productprofile/vaporflow/reflux differently. Sorry I'm not explaining this as well as I would like if anybody wants give me a call and we can talk about it.

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  • 3 years later...

I'm really interested in this topic as I've found that condenser water temp can make a difference when making brandy in a simple pot still, I just haven't figured out the pattern. Unfortunately, my french is terrible. Anyone know a book in English that covers this well?

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+1

I'm really interested in this topic as I've found that condenser water temp can make a difference when making brandy in a simple pot still, I just haven't figured out the pattern. Unfortunately, my french is terrible. Anyone know a book in English that covers this well?

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We're on an open flame, so for safety purposes we have an operating rule to keep the spirit temp under the flashpoint. If it goes over the flashpoint, you must address the problem. If it goes over the flame point, shutdown immediately, period. And we have a chart on the wall of flashpoint and flame point at common operating proofs.

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There are three posts here about coolant and distillate temp within a few hours and none of the same people involved, hmmm....

Safety says that the coolant outflow from the PC should run between 125-140 deg F (test your PC) to assure all vapor being condensed.

Water/energy conservation says maximize water temp to save on water and/or power circulating the water. Again "supercooling" (anything colder than needed for 100% reflux or Product Condenser) the water in a delpheg or reflux coil is another energy waste.

Temp of distillate collection vs product quality or refinement. This would almost be the basis of reheating to remove unwanted fractions or ultrasonic aging.

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Condenser temperature is a big consideration when sorting out your SOPs. I agree with the methodology of running stripping runs at elevated temperatures, and typically my distillate comes off the parrot at about 103-105 F...any warmer and my alcohol vapor to air ratio in the building goes above acceptable range for my municipality (over the course of a day)

When I'm doing the spirit run, I like to keep my product around 60 F...and this is mostly for convenience, as my hydrometer readings at the parrot don't have to be corrected much. Bear in mind, I'm talking whisky, here.

The original poster was concerned with an apple product, and I concur that with fruit based distillates on simple stills (ie no plates, dephleg, or catalyzer) the temperature of the condenser and the product is of paramount importance for consistency. The issue is that the changes are very subtle, and many people, trained in sensory or not, simply cannot taste a difference until the change is 15 degrees or more in take off temp.

I think a good starting point is around 80, and make 10 degree changes up and down before tasting. That's probably what I would do.

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To answer sorghumrunner's question, I can tell that coolant temp, and even room temp, make a difference in my products. But my condenser is tied to lines running through the still head (a modified Col'n Wilson still) and I don't have complete control of every variable. So I live with it.

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I just read through Hubert Germain-Robin's book (this isn't a product review, I swear!), and he talks a little bit about distillate temperature for brandies at different parts of the run and the impacts on flavor. And yes, it's in English. Not sure if you've seen that one, Nat.

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Just bought it, but it's about 4 weeks away from being read...:-)

Sounds like it's going to end up being one of those classic tomes we all refer to...

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On the aspect of cooling water exit temp; if your cooling water is running into PVC you need to make sure you keep it below 120F or you will start melting the plastic. I let my cooling water get up to 140F as its going into a concrete floor drain for 30 feet before hitting any plastic. Just something to keep in mind..

Just looked up the flash point chart and it seems my distillate temp is typically above that point for most of a run.

The flash points of ethanol concentrations from 10% ABV to 96% ABV are shown below:[36]

  • 10% — 49 °C (120 °F)
  • 20% — 36 °C (97 °F)
  • 30% — 29 °C (84 °F)
  • 40% — 26 °C (79 °F)
  • 50% — 24 °C (75 °F)
  • 60% — 22 °C (72 °F)
  • 70% — 21 °C (70 °F)
  • 80% — 20 °C (68 °F)
  • 90% — 17 °C (63 °F)
  • 96% — 17 °C (63 °F)
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On a pot still, the colder the liquor is, the better. Those with a deplegmator. Be sure to run a water line straight to it to bypass the condenser. You can send cold water directly to it, this can make a huge difference in controlling the column. On a beer still, it is normal to run above 70 degrees on the whiskey temp. Let's low boilers come out at it goes through the tail box. Go into a large distillery, you will notice most have vapor condensing on the glass of the tail box. Over 80 is too hot. On a pot, 60 is too hot.

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My condenser water exits 60 to 70 F below the temp I need my depheg. That seems like plenty of delta T to me. When I run straight cold to the dephleg (I can with a bypass) find that even the tiniest shots of cold can overcool it and stall my still.

Most of us on this forum are running relatively small stills, and the volume of cooling water needed is far smaller than a 2000 gallon pot still...where the sheer volume of vapor going through the dephleg can heat it up in moments. I can see needing a better flow and longer delta T for that.

The thing that's fun about this industry is all the different paths that can lead to the right answer. Of course, when you hit the size where saving a tenth of a cent per gallon saves you a thousand dollars a day, certain processes will be the same, but I love nothing more than buying and drinking product concocted on the most ridiculous Rube Goldberg setups...and by and large, that's the stuff that is delicious!

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