Speed of stripping & speed of spirit runs

[biggybigz]

Hello gang!

Happy Thanksgiving! I am developing my own however, I am looking for feedback/input on the speed of stripping runs and spirit runs with my rig. Below is what I have.

13gal pot
2" pot still column 12" tall
5/8 diameter Liebig arm 32" long
240 volt SSR controller with 5500w element

For stripping run....as fast as it can go?

Spirit run....slow and low 2-3 drips per second?

On stripping runs I am afraid of going to fast due to scorching or stripping out too much flavor.

Any input would be greatly appreciated. Thanks!

[S-Cackalacky]

As fast as it will go for stripping without over-powering the condenser. You can somewhat mitigate the possibility of scorching by clearing the wash as much as possible.

For the spirit run, run slow through fores and heads - a steady drip. When you think you're into hearts speed it up to a pencil lead sized stream. Collect in 1/2 pint (or less) jars for doing cuts.

[still_stirrin]

...On stripping runs I am afraid of going to(o) fast...stripping out too much flavor...

Just the opposite. Stripping fast will carry over more flavor.

It'll smear from front to back. But that's OK, because its just a 1st pass to raise the %ABV to low wines.

Then, on your spirit run you can go at a more reasonable pace. But if your spirit run is also using the potstill, you really just want to pull it back to the point where you get a small stream (pencil lead size). Slower than that and you're spending time for nothing.
ss

[biggybigz]

Ok great. I really appreciate the help!

[Badmotivator]

I've been wondering about this question for a while now: In a pot still setup, what effect could speed (power) have on the order in which the different chemicals come over? I understand that power controls vapor quantity (speed), but I thought that the idea that power affects vapor composition in any way is called the Magic Boiling Myth.

In other words, why not run spirit runs at full speed?

[still_stirrin]

....In other words, why not run spirit runs at full speed?

In a word....smearing. Same as a strip....but in a strip, you're collecting for the low wines so you can blast through the strip, at least as fast as you can condense the vapor.

Now, if you're running your spirit through a column with reflux, the reflux ratio affects the purity, that is...the more reflux the higher the purity. That is where you fraction the good drop from the bad. In a potstill spirit run, you have to rely on good cuts.
ss

[Jolly_Roger]

I'm still a noobie.
I think it all depends on what you want the final product to be. For example. If I were running Rads All Bran (through my pot still) and wanted to make a neutral. I'd take my time with both the stripping run and the spirit run. Alcohol content over flavour. However if I wanted to make a "faux" whiskey I'd strip as quick as possible to get some flavour to come with it.

The experts here may have different ideas tho

[Badmotivator]

What I'm asking is: HOW could pot still strip run power adjustment affect smearing? Smearing is a fact of life in a pot still; just like you can't change the ABV by controlling power (Magic Boiling Myth), you can't change the concentration of any chemical in the vapor at any time using power, right?

[still_stirrin]

Well, fores and heads can smear throughout the run if you boil vigorously.

What happens is that the fractions are entrained with other constituents in the mixture. As the heads are boiling up, some of the hearts get drug along, especially since the boiling points are very close to each other. If you're pushing a lot of heat, you'll pass through temperature zones where the heads and hearts likely are boiling at the same time.

On a spirit run, the temperature will rise more gradually with heat input, allowing the lighter (lower boiling point constituents) to boil off more thoroughly before the hearts come to full production. The same thing happens towards the later (hearts to tails) transition.

The boil rate affects the degree of smearing in this way.
ss

[still_stirrin]

...just like you can't change the ABV by controlling power (Magic Boiling Myth)...

I'm curious what you mean by this myth....

Are you meaning, "that you can't run a potstill by temperature", as many new distillers have difficulty understanding? Or, "that you can't set your PID to 173*F and pull pure ethyl alcohol"? Both of which relate to the liquid composition of the mixture...a chemistry lesson for you to read about.

As has been stated many times (which I'm sure you've read about even though you may not yet understand) that the heat input (power) controls the rate of boil, not the temperature of the boil. The temperature of the boil is determined by the composition of the liquids in the mixture (because the constituents all have different saturation boiling points) and because you're changing the mixture constantly throughout the boil, the boiling temperature changes as well.
ss

[Jolly_Roger]

Smearing-heads pushed into hearts and hearts pushed into tails?

[Badmotivator]

...just like you can't change the ABV by controlling power (Magic Boiling Myth)...

I'm curious what you mean by this myth....

Are you meaning, "that you can't run a potstill by temperature", as many new distillers have difficulty understanding? Or, "that you can't set your PID to 173*F and pull pure ethyl alcohol"? Both of which relate to the liquid composition of the mixture...a chemistry lesson for you to read about.

As has been stated many times (which I'm sure you've read about even though you may not yet understand) that the heat input (power) controls the rate of boil, not the temperature of the boil. The temperature of the boil is determined by the composition of the liquids in the mixture (because the constituents all have different saturation boiling points) and because you're changing the mixture constantly throughout the boil, the boiling temperature changes as well.
ss

I may be misapplying the term "Magic Boiling Myth". The myth I'm trying to talk about may be different enough to deserve its own term. We can call it the "Power-Flavor Myth" or something. The myth is that a given mix in a pot still can be induced to boil "differently" by the careful calibration of power. Like this: Given a boiling mixture at a particular moment in the distilling process, low power would produce a vapor with one composition and high power would produce vapor with a different composition. If that were true then you COULD change your ABV by adjusting the power.

I'd be willing to wager that if you split some low wines into two spirit runs and ran them identically except for the power, and collected jars identically, and then analyzed the composition of all those jars, you would find that they are identical. That is, until some Chemical Engineer comes along and schools me on what I'm missing.

Like you said, the power controls the rate of boil. I'd like it to read: power controls the rate of boil but not the composition of the vapor.

[Monkeyman88]

The power controls both.
If you have a nice slow boil, only a small amount of vapour will come off. But if you have a very fast boil, a lot of vapour will come off. Smearing all the different volatiles.

[IanD]

...

I'd be willing to wager that if you split some low wines into two spirit runs and ran them identically except for the power, and collected jars identically, and then analyzed the composition of all those jars, you would find that they are identical. That is, until some Chemical Engineer comes along and schools me on what I'm missing.

Like you said, the power controls the rate of boil. I'd like it to read: power controls the rate of boil but not the composition of the vapor.

I think you probably get a tiny bit of reflux when you run slowly and that helps separate the fractions.

[still_stirrin]

...I think you probably get a tiny bit of reflux...

Ha! Well, a lot of things happen when you run a potstill (slowly), but "reflux" isn't one of them.

You have reflux when rising vapors in a column condense and descend back down the column, falling through more hot, rising vapors which causes some of the condensed liquid to reboil, especially the lighter (more volatile) liquids. The repeated condensation and reboiling is reflux and that is what separates the constituents.

A potstill is a single vapor path to the product condenser. If there is any passive condensation due to heat loss in the riser it would minimal, if at all. And once the riser is heated up, even passive condensation is very unlikely.
ss

[S-Cackalacky]

Rate of boil (power input) DOES control separation of fractions and percent ABV. Too much power in a spirit run does those things others have mentioned - smearing fractions into each other by vaporizing them simultaneously. Another component of the wash is also vaporized with a vigorous boil - water, which will lower the percent ABV.

It's true that a pot still will always smear to some extent, but you can control how much smearing takes place by keeping the boil rate at a lower level. That's why I recommend pulling fores and heads with a steady output drip. They're on the front end of the run and neither is desirable in your product, so why not, as best you can, narrow the transition of those fractions as much as possible so as not to smear them into the hearts. After the fores and heads pass, crank it up to a steady pencil lead sized stream for producing the hearts. It isn't nearly as critical to smear some hearts into tails. Tails usually age out and possibly add some positive flavor when used in moderation.

Smearing being caused by running to hard (to fast) is an accepted fact here - just like the fact that water runs down hill.

[still_stirrin]

...That is, until some Chemical Engineer comes along and schools me on what I'm missing...

While not a chem-E, I am a mechanical engineer. So I do have some formal education on chemical processes. I question your understanding of this, but I'll try.

The wash has several liquids dilute in each other...they're mixed together. Each one of those liquids has a saturation temperature, a point where they change phase from liquid to vapor (at a common pressure point too). And that phase change occurs at a constant temperature (a scaler measurement). However, it occurs as heat is added, meaning it doesn't just instantly flash. Rather each saturation point is really a "timeline", not an instant.

Now, the mixture has many different liquids, each with its individual saturation temperature. And many of those are close together, allbeit different. When you apply heat, as one liquid is nearing its completion to vaporization, the next liquid is beginning to vaporize, and the mixture's temperature will rise. With a low heat input (slow heat transfer rate), those vapors come off more discretely. But if you run with a high input, those saturation temperature "timelines" get smashed together and they vaporize (somewhat) concurrently.

Also, believe it or not, but the boiler has temperature variations within it as you progress through the boil. There are local hotspots by your electric element or burner while the mixing and churning of the wash liquid turbulate the heat to a more uniform temperature. But there will still be hotter and cooler eddies within the liquid mass. So, the liquids (again remember it is a mixture of ever-changing liquids) are heated to and through their saturation temperatures (somewhat) concurrently.

What we call, "smearing" is the output (product) of the nearly overlapping evaporation times of several liquids whose saturation temperature are very close to each other. Run with a high heat input and you produce more vapors AND you smear the individual constituents together. Run with a low heat input and you allow those constituents to vaporize more discretely at a lower production rate.

OK...not quite a textbook education...more like the "book on tape" version for you non-readers, but still I hope you understand the chemical processes a little better. And hey...no math was involved (although it sure could've been).
ss

[still_stirrin]

I also want to add that some of the oils which have higher boiling points (even than water) may not actually even reach their saturation point in the boil. But they do get carried along "for the ride" in the vapors, especially during a high heat input rate boil. This is called "entrainment". The oil molecules are intertwined with the alcohols, esters, diketones, etc. and as those liquid volatiles change to vapors, they drag the oils along with them.

This is where you get a lot more of the "flavors" carried over in a strip run (at a high heat input) opposed to a spirit run or even a strip run at a low heat input. Again, this is a "rate" consequence.
ss

[IanD]

...That is, until some Chemical Engineer comes along and schools me on what I'm missing...

While not a chem-E, I am a mechanical engineer. So I do have some formal education on chemical processes. I question your understanding of this, but I'll try.

I'm trying to understand this and there are things I'm not getting. Please bear with me.

The wash has several liquids dilute in each other...they're mixed together. Each one of those liquids has a saturation temperature, a point where they change phase from liquid to vapor (at a common pressure point too). And that phase change occurs at a constant temperature (a scaler measurement). However, it occurs as heat is added, meaning it doesn't just instantly flash. Rather each saturation point is really a "timeline", not an instant.

My understanding was that the saturation temperature of a mixture of liquids follows Raoult's law (with some positive or negative deviation for non ideal liquids) so there is a modified saturation temperature for the mixture. I appreciate that the energy is required for the phase change i.e. enthalpy of vaporisation.

Now, the mixture has many different liquids, each with its individual saturation temperature. And many of those are close together, allbeit different. When you apply heat, as one liquid is nearing its completion to vaporization, the next liquid is beginning to vaporize, and the mixture's temperature will rise. With a low heat input (slow heat transfer rate), those vapors come off more discretely. But if you run with a high input, those saturation temperature "timelines" get smashed together and they vaporize (somewhat) concurrently.

I don't doubt that this happens but I really don't understand the mechanism. I'd like to see some proper physics here.

Also, believe it or not, but the boiler has temperature variations within it as you progress through the boil. There are local hotspots by your electric element or burner while the mixing and churning of the wash liquid turbulate the heat to a more uniform temperature. But there will still be hotter and cooler eddies within the liquid mass. So, the liquids (again remember it is a mixture of ever-changing liquids) are heated to and through their saturation temperatures (somewhat) concurrently.

This I can believe. That's a plausible mechanism for smearing.

What we call, "smearing" is the output (product) of the nearly overlapping evaporation times of several liquids whose saturation temperature are very close to each other. Run with a high heat input and you produce more vapors AND you smear the individual constituents together. Run with a low heat input and you allow those constituents to vaporize more discretely at a lower production rate.

OK...not quite a textbook education...more like the "book on tape" version for you non-readers, but still I hope you understand the chemical processes a little better. And hey...no math was involved (although it sure could've been).
ss

I'd very much like to see the math.

[IanD]

I also want to add that some of the oils which have higher boiling points (even than water) may not actually even reach their saturation point in the boil. But they do get carried along "for the ride" in the vapors, especially during a high heat input rate boil. This is called "entrainment". The oil molecules are intertwined with the alcohols, esters, diketones, etc. and as those liquid volatiles change to vapors, they drag the oils along with them.

This is where you get a lot more of the "flavors" carried over in a strip run (at a high heat input) opposed to a spirit run or even a strip run at a low heat input. Again, this is a "rate" consequence.
ss

That's interesting. I didn't know about entrainment. Some serious reading required I think.

[IanD]

...I think you probably get a tiny bit of reflux...

Ha! Well, a lot of things happen when you run a potstill (slowly), but "reflux" isn't one of them.

You have reflux when rising vapors in a column condense and descend back down the column, falling through more hot, rising vapors which causes some of the condensed liquid to reboil, especially the lighter (more volatile) liquids. The repeated condensation and reboiling is reflux and that is what separates the constituents.

A potstill is a single vapor path to the product condenser. If there is any passive condensation due to heat loss in the riser it would minimal, if at all. And once the riser is heated up, even passive condensation is very unlikely.
ss

It may well be minimal (I did say a tiny bit) but there must always be some reflux happening. If the riser is hot (can't touch it) then it is losing energy to the air around it. This must come mostly from enthalpy of condensation (and a very little from conduction up from the pot.)

[biggybigz]

I have learned a lot from this post. Thank you to everyone chiming in on my questions about speed blah blah blah stuff.

My strip run has aired for 72 hrs. I can feel, smell and taste the smearing. I collected in full quart jars. I started out slow and threw away 400ml of fores. There is really only one jar, right in the middle of the run that is hearts. I would safely assume this is because of smearing. It's super yummy.

My own version of UJSM.

10lb cracked corn
10lb all grain sweet feed
15gal super awesome Missouri well water
25lb sugar
Big ole fat distillers yeast bomb.
25%ish backset from previous run
Blended with a drill and mortar mixer vigorously to blend sugar and get some oxygen in there.
For my taste buds it's making a yummy drop.

I always rack the left over wash into a separate food grade barrel and throw some in the spirit run.

I figured I should tell you guys what I am running in case you had any other input and any other advise. Again, I really appreciate the help!

[still_stirrin]

...I collected in full quart jars...15gal...water (+) 25%ish backset from previous run...any other input and any other advise...

Only thing I would suggest, for this size wash...to use pint jars for collection. It may allow you to "expand" your heart section a little. It just gives you a finer degree of subjectivity of where to cut, returning less to the feints (rerun) jar.
ss

[raketemensch]

When I did my spirit run on my pot still last weekend, I only fired up the lower fan (at the bottom of my hot water baseboard condenser) to see if leaving the top fan turned off would speed up warm up time.

It did, by a good 30 minutes. Lesson learned, right? Fores were dripping at a good pace, so I turned on the upper fan, and drips stopped, for at least another 30 minutes. The fan is aimed away from the column, so it must have been just the heat conductivity of the copper combined with the finned baseboard that cooled everything down, and created a little reflux.

Maybe that's part of why I was able to end up with such wide cuts? To be honest, I don't have a working controller, so both strip and spirit runs were done at the same 1375 watts, so the only difference for the "spirit" run was that it was a second distillation.

This thread also has me wondering -- we tend to talk about reflux *only* in the context of going for neutrals, but would a little reflux almost always be a good thing? I've designed some fins for the top of my 2" pot column that should create some reflux, although not enough to knock everything down -- which I'm OK with, I don't want a neutral.

But is there a certain amount of reflux that would be good for creating flavored spirits?

[still_stirrin]

...would a little reflux...be good for creating flavored spirits?

First, very good anecdote with your air cooled product condenser. Exemplifies the conductive (heat transfer) capability of copper...much more than stainless. What you hypothesized and observed is exactly what happened.

Using the still and its features can exploit the physics to produce a different (better?) product...in your case, a higher proof output, and to some degree, better separation of fractions. You've managed to "massage" your lady to give you what you want...errr...need!

Yes, you can make a difference in flavor (and proof) by "dialing in" your system. That is the artist in the form of art as we hobbiests focus on our product and less on "the drunk".

Thanks raketmensch. Good input.
ss

[biggybigz]

...I collected in full quart jars...15gal...water (+) 25%ish backset from previous run...any other input and any other advise...

Only thing I would suggest, for this size wash...to use pint jars for collection. It may allow you to "expand" your heart section a little. It just gives you a finer degree of subjectivity of where to cut, returning less to the feints (rerun) jar.
ss

On my spirit run I will. I don't have a large vessel to collect everything in. Quart jars are all I have at this time. Are you guys keeping the heads out of your spirit run? That's the only reason I could think of why you would want to keep things separate in a stripping run. Am I thinking correctly on this?

[Swedish Pride]

SS
That is a fantastic explanation of what happens in our potstills, i never knew the ins an outs of it , only to run at pencil-lead size stream to make a better product.
thanks for this, i vote for it to be mover to somewhere in the novice destillers section. to good of an explanation to be lost in all the pages here

[RedwoodHillBilly]

This thread also has me wondering -- we tend to talk about reflux *only* in the context of going for neutrals, but would a little reflux almost always be a good thing? I've designed some fins for the top of my 2" pot column that should create some reflux, although not enough to knock everything down -- which I'm OK with, I don't want a neutral.

But is there a certain amount of reflux that would be good for creating flavored spirits?

I'm not sure about this, but isn't a small amount of reflux similar to using a thumper? Other than the ability to add flavor with the thumper liquid.

[S-Cackalacky]

One way to stabilize the thumper to help prevent some of the smearing might be to put its output into reflux until all the liquid in the thumper is up to heat. This has been discussed in other threads related to stabilizing a steam boiler. One simple recommendation was to point the end of the liebig toward the ceiling - allowing the output vapor to reflux back into the thumper (steam boiler) until the thumper is evenly heated and then switch the liebig to its normal position for takeoff.

I've also read posts in other threads about creating a primitive dephleg at the top of a pot still riser by coiling copper tube around it and feeding it with cooling water. I don't think there was a thread dedicated to the idea and I'm not sure how effective it was at increasing ABV or sharpening the cuts.

I kinda like the idea of taking steps to stabalize a thumper before releasing its output, but I'm not so sure about creating reflux in a pot still riser. It would seem that it would be something other than a pot still at that point.

[skow69]

For anyone who has never tried this, I highly recommend that you do. It will give you new insights into distillation in general and your rig in particular.

Get a stripping run going balls out like normal. Test for purity. [Use a parrot or swap jars and test as necessary.] Reduce the heat to a minimal boil/drops per second. Note the increase in ABV. Crank the heat back up and watch the ABV drop. Repeat for an ABAB test format until you are convinced. The effect is way more powerful than most of us would expect. The change in ABV is inversely proportional to the change in heat input. Not temperature, mind you, (although you will see that rise and fall also if you monitor the vapor) but heat input. You are still not controlling anything by temperature. The temp change is an inconsequential result of varying the heat input.

I believe in partial pressures. I do not think this violates Roult's law, Dalton's law, or any other part of the accepted theories of thermodynamics. I assume that this effect is primarily due to passive reflux, as well as entrainment, whatever variations result from mixtures not being ideal, and other perfectly logical anomalies that are above my pay grade. I do not have the expertise to demonstrate mathematically how much each of these contributes (and I think it is obvious that no one else in this discussion does either) but I am confident that it can be done.