Effects of Packing in Column W/Out Active Reflux

[flyingdutchman]

I understand that this is not the norm here however that does not imply that it doesn't work. It is actually a common laboratory practice.
With out packing what we call running a pot still is considered a simple distillation. With packing it is considered a fractional distillation. This can be seen here...
http://www.erowid.org/archive/rhodium/c ... mmies.html
It is also covered in the Compleat Distiller (see 2nd edition,Fractionating columns page 82)

Based on this I wanted to measure what kind of difference structured packing (SS scrubbies) would make when added to a pot still.
The pot still/column I use can be seen herehttp://homedistiller.org/forum/viewtopi ... 8#p6976418

For reference I did a stripping run with no packing. Starting with a wash of 13.9 % ABV (~ 8 Gal), I collected a stripping run. Here are the results with temperature corrected ABV readings for no packing. After discarding the initial 100mL(as foreshots) I observed the following..
Conditions
* Intial ABV: 13.9%
* Collection Rate: thin broken stream
Results
* Collected ABV: (temp corrected) ~60%

As expected this was essentially(with no packing) a one plate separation
as predicted here..http://homedistiller.org/theory/refluxdesign/steps
and here...http://homedistiller.org/calcs/husker_pot_calc_v2.php

To test the effect of packing w/out active reflux, I took a collection of low wines ABV 37% (~5 Gal). I packed the same column with ~12"-14" of SS scrubbers. It is difficult to give the precise length as surely some compression of the packing occurred when inserting it into the column. Then insulated said column. I had absolutely no active reflux but used strictly power management and what we might call passive reflux. After discarding the initial 100mL(as foreshots) I observed the following....
Conditions
*intial ABV: 37%
*Collection Rate: ~ 3 drops per second
Results
*Collected ABV:(temp corrected) 86% (for 1st 300 mL)

Then I increased the take off rate
* Collection rate: ~6/7 drops per second
Results
*Collected ABV:(temp corrected) 83% (2nd 300 mL)

Results
So with the packed column ,at my initial takeoff rate, using only power management and passive reflux I would say that...
12-14 packing = ~ 1 extra theoretical plate
again based on this http://homedistiller.org/theory/refluxdesign/steps
AND consistent with this tool http://homedistiller.org/calcs/reflux_calc when I estimate the reflux ratio to be 0.01

Notice that if I had only 1 plate as before the predicted ABV would have been significantly lower than the observed ABV.
Also notice that when I increase the takeoff rate my ABV did drop some so as would be expected (yet it was still well above the previously observed 1 plate result w/out the packing).
Of course it goes without saying that if we add active reflux We would get a much better separation than we did. Still I think these results indicate that adding structured packing makes a definite measurable difference in a pot still.

What might this be good for?
What effect does this have on taste?
ps
If in doubt please don't take my word for this repeat what I did and post your results! If I made a mistake post your results I absolutely would not object!

ps
I didn't post this to the pot still section as it seemed more like research/theory

[Mr Shine]

Why don't you test again, with only the one variable of the added packing? Say you stripped a 13.9% wash with packing and the same takeoff rate.

I think you'll find that any added perceived increase in ABV can be attributed to the speed you take the product of the still at.

It would be interesting if you ran another few runs, including doing a stripping run and then spirit run without packing and then doing it with packing with the same wash, at the same takeoff rate. I'd bet the results would be pretty close. But there's only one way to really tell.

Interested in hearing more though. Thanks.

[pfshine]

The test was flawed due to the different initial abv. No offence but in order to say anything there can be no difference in any variable. Ambient temp should be the same initial abv should be the same and power input should be the same along with many other things in order to be able to say x does what. I do applaud you on yor effort to answer these questions.

[flyingdutchman]

Hi all,
Yes this is sadly true I do have a difference is several variables and need to run this again under better controlled conditions. It was late in the year and I had just a few warm days to fool around. Right now its just too cold up here
However it is worth repeating and I will when it warms up. Please do read the literature references I posted (Nixon and Zubrick) because they already published on what I am trying to do.

Merry Xmas!
FD

[rad14701]

In order to come up with verifiable data more experiments would be required... I did a bit more work on my new boiler today so I could get some runs done but ended up one step back, unfortunately, due to not having a decent work area yet...

To get good data you would need to have enough wash for 2 - 4 runs... The wash would need to be run at a specific heat input setting in both without and with structured packing... All runs should also be done at a specific take off rate measured over time... It could be full out stripping or a specific volume per minute... Then a second run of the low wines would need to be run in the same manner... At least this is how I intend to do my experimental runs... And I am hoping to run with multiple packed column heights...

Good start, flyingdutchman...

[DAD300]

Ta Da...flyingdutchman, I agree with your findings.

Any column that will make azeo with reflux will produce at least two distillations high 70%- low 80% without reflux.

When last I did this a 2" x 48" column with scrubbies that struggled to make azeo from a 12% was, would do ~80% with the reflux out and the top capped.

Guys, it is very disconcerting to have people say something definitely does not work, when they have not tried it!

Now it may be because there is some passive reflux in a tall column and it may be that the packing accomplishes a second or third distillation on it's own. Maybe just like a thumper does??????

Merry Xmas to all and to all a good drink!

[flyingdutchman]

Thanks for all the replys!
My comparison between packed and unpacked was truly lacking LOL.
However it was encouraging that in the spirit run I got the equivalent of 2 plates from a pot still (with packing) so I figure its worth trying again.
Honestly my guess (but its only a guess) is that no matter how slow I run my hobby scale pot still (w/out any packing) it will never get more than about ~1 plate (of separation). But thinking that is one thing and showing it is another. The recommendations made were spot on and before making any big conclusions it needs solid proof.
So I have a couple of days coming up where we should hit the 40'S around here and I have some feints kicking around. So here's my thinking..
1) dilute feints to around 20%
Now 1 plate would be ~66% and 2 plates would be ~83% that's a big enough difference it could be easily measured
2) Insulate column but use no packing and bring it slowly to temp.
3) Set flame (yes propane ) to ~ 1/8 of inch and collect 1st 300 mL at 2 drops per second
4) Take 300 mL sample and get temp corrected %ABV
The difference between initial %ABV and final % ABV should tell me how how many (theoretical plates) I had for unpacked
5) Kill boiler and allow to cool.
6) Remove Column and add all collected distillate back to original boiler
Now I should be back where I started and if anything have slightly less alcohol for my second run and result in a lower %ABV than expected
7) Pack column with ~12"-14" of SS scrubbers
8.) Repeat step 2(packed now),3,4
The difference between initial %ABV and final % ABV should tell me how how many (theoretical plates) I had for packed column
Now with an insulated column, ~ the same temperature in my garage, the same wash, the flame adjusted to the same height (as close as possible), and an identical collection rate, I would say I am very close to the same power input and so reasonably test conditions.
So if there is a difference between the number of theoretical plates for packed vs unpacked, (within experimental error) the difference can be attributed to the packing.
I am open to all ideas and comments before I try it and welcome any input!

[flyingdutchman]

Hey,
Hope everyone had good Christmas!
Its snowing now but is supposed to hit 44F on Sunday so I am going to give this a go. If anyone that wants to check or repeat this I encourage it. No matter what my results are it isn't really proved till it works for someone else
DAD
Thanks for the encouragement and for sharing your results I appreciate it.
RAD
Sorry to hear about your setback with your new boiler hope it works out ok.

[Prairiepiss]

Hoe are you going to be comparing the two runs. Seams to me the only measurable thing you can test is ABV. So are you basing the whole thing on ABV alone? Maybe takeoff speed? But in what relation? And speed isn't always an accurate measurement.

And I would also say the only way you could get a good test out of this is.

If you used a previously distilled boiler charge. That was diluted to a set ABV. And the ABV tested when the boiler was charged. And all tests done with the same tested ABV to start with. A fermented wash can't be a control. They differ widely. And I have seen where runs from the same batch ferment had different results.

A set heat input should be used. So the same heat is put into the open column as the packed column. So the results will show what will happen at the same heat setting.

Another one could be a set takeoff speed. (again not always accurate) This would show if the re is a difference between the two at the same takeoff rate.

What were your thoughts on what and how to test it?

[MitchyBourbon]

rad14701 wrote:

The wash would need to be run at a specific heat input setting in both without and with structured packing... All runs should also be done at a specific take off rate measured over time...

How do you control output rate if you are also controlling heat input on a pot still?

[friendly1uk]

I hear it won't work quite often, but some pretty simple physics says it will. You can get a much more controllable temperature gradient and the stuffing is more hoops the water vapour must interact with before it can get out. Giving a greater volume of water recondensed and sent back.

This is not comparable to a reflux still though. Setting up that gradient would take care and flow rates might be very low. It can certainly work though, there is no need to test the idea. I can just point you to existing data which I believe has already been seen in many lab tests. You can buy such equipment. It is way past theory.

[flyingdutchman]

HI PP,
Good to hear from you!

If you used a previously distilled boiler charge. That was diluted to a set ABV. And the ABV tested when the boiler was charged. And all tests done with the same tested ABV to start with. A fermented wash can't be a control. They differ widely. And I have seen where runs from the same batch ferment had different results.

Agreed a cant use different starting points and try to say there is a definite difference.

ABV
My idea at this point is to charge my boiler with saved feints that I will dilute to a set ABV (20%).
I wont try it with a fermented wash (exactly because as you point out they will always be different). Both runs need to be at a fixed ABV (and run conditions, but lets talk ABV first)

Now if I run the column unpacked and collect 300 mL, The difference between the intial ABV of the ABV of the collected sipirts will tell me for those conditions how many steps/theoretical plates I achieved.
Now I wont collect any more. Infact I will shutdown the heat to my boiler and let it completely cool down. Then once cool if I remove the column and add all the collected spirits (300 mL) back to the boiler charge The boiler should be back at the original ABV (or even just a little less). I can even recheck it before I start to make sure its right where it should be.

Now I will add the packed column fire up the boiler and collect 300 mL for the packed column. Again the difference between intial ABV and final ABV can be used to calculate the number of steps/theoretical plates.

Hi Mitch here is what I am thinking here....
HEAT INPUT
Now for heat input vs takeoff rate. Forget everything else and pretend this was just water. If I apply the exact same amount of heat under identical conditions (n a still) for the same water, I believe I would get the same output/takeoff rate because the heat of vaporization for water does not change. So if we apply this idea to our boiler charge and it is the exact same composition and so the same heat of vaporization so identical take off rate should mean (under identical conditions) equal heat input.

Now here is the beauty of doing the packed column for the second run. One could argue that the second charge might be a little less alcohol and so not identical but how would this effect the test?
1) IF we had less alcohol in the charge (for packed column) and all other conditions identical, (if packing made no difference) the ABV of the packed column would be less than the unpacked. Same number of plates lower initial ABV means lower final ABV.
2) IF we had less alcohol in the charge (for packed column) then that means its more water than ethanol in the mix. But that means it takes more energy to transition from liquid to vapor. That means if anything I would be adding more heat. That means if anything the unpacked column will be getting run slower.

So for both cases I am loading the dice in favor of the unpacked column.

[flyingdutchman]

Hi friendly,

This is not comparable to a reflux still though. Setting up that gradient would take care and flow rates might be very low. It can certainly work though, there is no need to test the idea. I can just point you to existing data which I believe has already been seen in many lab tests. You can buy such equipment. It is way past theory.

I couldn't agree more. In fact I do, do this in the lab for a completely different application. This is exactly why I posted the reference to Nixon and McCaw's book (where he describes building and using this type of still for ethanol production) as well as the undergrad laboratory manual for organic chemistry.
However I really do not see people using this to any large extent. Perhaps it has its own advantages that could be exploited. How fast can it be run? Clearly 1 drop per second is like watching grass grow and if the only point is to compete point for point with a compound reflux still I am obviously wasting my time.

But ..
1. Maybe It can be run slowly at say 3 drops second just to compress the heads.
2. Then what if we speed up the take off fast enough to just get a second plate and fore go double distillations for flavored products.
3. When pushed like so under these conditions is it possible packing wont "trap" flavors?
4. Would this make pot still's with about 15-20" column lengths more versatile?

I dont know but it interests me

[Ayay]

Great experiment! I have done pot runs fast and slow, with and without packing, but not as a controlled expeiment. So my observations are just a hunch that the packing does very little when stripping, and maybe quite a bit when doing a slow spirit pot run. The results from accurate comparisons will be very interesting.

Passive reflux means there is no control of the output speed except by controlling the heat inpt, the same as pot run. If there is any other control of the output speed, then there will be forced reflux.

[MitchyBourbon]

I totally get your experiment and the notion that packing the column might have a noticeable effect.

My question was aimed at what parameters should be held equal to perform a valid comparison. If you control the heat input ie heat input is the same, how can you force the take rates to be the same? It would seem to me that you would hold the heat input equal but that there isn't anything else you can do to control take off rates.

[flyingdutchman]

Hi Mitch,
My problem is that I use a propane burner. I do not have a controller with a fixed wattage output so I could never rightfully insist I have exactly the same exact heat input. No matter how careful I am, my fear is that anyone could rightful disagree with my results.

So I need an alternate way to show that I have the same heat input or it is at least a fair comparison, which forces my to use my output rate.

Now inside the actual boiler since it is exactly the same boiler charge both times, then it will take exactly the same amount of heat energy to vaporize an equal amount.

This leaves 2 possibilities
1) There is no passive reflux going on with the packing in which case exactly the same amount of heat energy input rate will give me the same distillate output rate
2) There is passive reflux in which case it will actually mean i have to add more heat energy to the packed column to get the same take off rate.

If you control the heat input ie heat input is the same, how can you force the take rates to be the same?

I believe #2 is what you are saying. Because we get if reflux then for equal outputs the heat input wont be the same?
And if it is what you mean i agree it wont be the same (though I would guess we are talking about a reflux rate of around 0.01 to 0.1)

But for that to be true we have to have reflux which is what I am trying to prove. Because if we have packing and reflux we know we get a better separation from experience.

And even then (if we conceed that there is indeed reflux )it only means I am adding more heat energy to the packed column than the unpacked. That in turn stacks the odds in favor of the unpacked performing better if the argument is that i am running the unpacked column too fast.

I hope i answered your question and didnt miss the boat?



Hi Ayay,
Yep it would be a total power management setup. Yes what you saw is what i have seen, pushing too hard would mean its essentially just a pot still. Maybe there is a sweet spot where with enough packing and correct power input we can get the best of both but I am not sure.

PS check out Zubric he insists and I have seen in glass columns in the lab that with proper heat application you can put these setups in total reflux.

[Ayay]

To keep everything the same for the experiment...
Ambient temps...record them.
The rig - in my case a boiler, a 2"x30" riser and a 38" leibig. Packing and insulation of the riser to be the variables.
The charge - a large wash or a few strips, mixed and/or diluted into one container, and then split into idendical halves for the two runs; or 4 identical quarters for 4 runs (2 at slow output speed and 2 at fast speed).
For every run go full blast until the first drip appears and then adjust the heat to the desired output speed and do each run at the same output speed, regardless of the heat required. The output speed and the alc content can be measured accurately, and the difference in alc content between the runs with packing and the ones without, will be the answer...I think. Monitoring and adjusting the output speed will take constant attention and fiddling with the heat, but if achieved then everything should be the same, except for the packing and the alc concentration coming out, and if there is a difference in alc concentration there will be a difference in the total volume of the outputs.

The end of each run can be defined when the output drops to 20%, or 10%. Using a parrot will introduce some inaccuracy; collecting in small jars without a parrot will make finding the end harder. I think the experiment is doable with enough accuracy to give very useful information!

[flyingdutchman]

Yes that sounds good to me.
Really I think the best way is to compare is to calculate the number of theoretical plates for each set of conditions you choose to run. That way we are comparing apples to apples.
Theoretical plates and vapor phase diagrams have been covered extensively here and people here have been kind enough to generate graphs
This is a couple of links from a quick search: http://homedistiller.org/forum/viewtopi ... e#p7134269
and herehttp://homedistiller.org/forum/viewtopi ... =1&t=10158
and calculators: http://homedistiller.org/theory/refluxdesign/steps

Mind you the boiler is the first plate so the total number of plates achieved(call it N) minus the boilers contribution tells us the number of plates the actual column itself generates.
So Plates(column) is N-1

[DAD300]

I don't think it's all that complicated...

Using http://homedistiller.org/calcs/pot_calc" onclick="window.open(this.href);return false;" rel="nofollow

If you can produce more than the home calculator says from a given wash, you got "X" extra theoretical plates.

And you can figure out how many plates by using http://homedistiller.org/calcs/reflux_calc" onclick="window.open(this.href);return false;" rel="nofollow with the reflux set to .001. The calc won't let you use zero reflux.

And I have achieved hearts of 80% with no reflux...in a 36" scrubbie packed column.

So according to the calculator, I got ~ 3 plates...the pot plus 2 in the column. Sounds better than running a thumper, unless you'r using something special in the thumper for added flavor.

While the variable of the heat input and the ambient temp is a nice idea...the wash ABV and the output ABV are the greater factors. On any given day the wash, lack or added packing will be the only true constant.

That said...I'm awaiting the data you'll generate, simply because it should end a debate!

[flyingdutchman]

Thank you DAD
Yes Exactly!

In fact if we look at my first pot still run it had exactly what the pot still calculator http://homedistiller.org/calcs/pot_calc said it would 1 plate!
You can also look here and get the tool for predicting 1 plate for any intial ABV just plug in 1 plate. http://homedistiller.org/theory/refluxdesign/steps.

Now if we subtract 1 plate for the boiler we get 0 plates for the unpacked column! See the unpacked column made essentially no contribution (as we would have predicted it is just a short hollow tube!).
Distillation works by cycles of evaporation and condensation each one being a theoretical plate. We need a lot of surface area for this to occur , where does that happen in a hobby scale short hollow tube?

Anyone who cares to please go ahead and check the with these calculators and you will see that regardless of intial ABV, for a pot still it is just predicting one plate (the boiler!). It does not care what the starting ABV is it works by how many plates (theoretical) you have. So if start with 10% ABV it predicts 1 plate, if I start with 40% ABV it predicts a separation of just 1 plate. That's why I wanted to work in plates.

Ps
I would guess you got an HETP of 18" for the conditions you ran at which is not all that different for the HETP of 12-14" for the conditions I ran at.

[DAD300]

Reflux doesn't add plates...it merely drops the condensed higher alcohol through the existing plates for a second pass...while dropping reflux can actually interfere with initial rising vapors use of the plates. Hope that makes sense. That's was the theory behind some early original external reflux designs, drop all reflux to the bottom of a column.

[flyingdutchman]

OK
I finished both runs. What I got was not what I expected at all but here it is. All reported ABV numbers are temperature corrected.
1st run Pot Still mode
Conditions
Ambient Temp- 39 F (garage)
Boiler Charge: 3 Gal @ 18.7% ABV + 0.5%
Boiler: 15.5 gal SS 1/2 barrel
Column: 24" 2" copper as previously posted this thread
Burner :propane
Procedure
Loaded boiler, Attach and insulate column, fired burner adjust flame to 3/8". When column begins to warm but before any product reaches condenser, flame reduced to ~1/8 ". From experience this will produce a slow output rate.
Collection
Amount: 300 mL
Rate: ~2 drops per second
Alcometer reading: 84.5% ABV
Theoretical plates: ~2

Turned off burner, Cooled down unit with wet rags, wait 1.5 hours. remove column, add 300 mL collected spirits back to boiler. Recheck % ABV of boiler charge with alcometer.

2nd run Packed Column
Conditions
Ambient Temp- 40 F (garage)
Boiler Charge; Same ~3 Gal now @ 18.1% ABV + 0.5% (this 0.6% difference could be real or just error because its hard to read the scale in the 20% range)
Boiler: 15.5 gal SS 1/2 barrel
Column: Same column
Packing: ~12-14" SS scrubber (estimated since I cant see inside)
Burner :propane
Procedure
Attach packed and insulated column, fired burner adjust flame to 3/8". When column begins to warm but before any product reaches condenser, flame reduced to ~1/8 ".
Collection
Amount: 300 mL
Rate: ~2 drops per second
Alcometer reading: 86% ABV
Theoretical plates: ~2

It is worth mentioning here that I had some strange problems with my rig on this second run. I dont why know but I had some kind of intermittent surging with my product output. It would hum along at 2 drops per second then just stop and my column thermo would start dropping. After 10 to 30 seconds it would start to climb & out would come a fast stream of product, then settle back down again to about 2 drops per second.

Results:
Well I was really surprised to get 2 plates from the pot still. In fact I would have bet my last dollar that would not happen BUT it did.
Then the difference I saw between packed and unpacked was minimal at best. What difference I did see under these conditions seems inconsequential.
So that just leaves me with more questions
1)Where did I get enough surface area for an extra plate?
* Was it all the cold temps combined with a boiler that was only filled ~ 1/5 of the way?
* Would running at warm ambient temps reduce this effect
* Is my column length and shape making that much of a difference
2) Why did the packing have so little effect
* Did it all bunch up when I pushed it in?
* Does it need to be run much much slower to have any effect (if so this might be completely useless to us)
* would a packing material like SPP with a much better HETP have a greatly improved effect?
* Would 1 or 2 cooling tubes CM style fix (then cut flow after the heads are collected ) CANT take credit for that idea I saw another member post it and i liked it (sorry cant remember who it was)

So thats my results. Any thoughts??

[rad14701]

Unless someone does additional tests you've proven what we've been saying right along, that packing in a pot column has little effect once the column is up to temperature...

One thing to try, if you do try again, is to use original wash for both tests rather than mixing everything back together... That would give more consistent starting points...

[flyingdutchman]

Hi Rad,

Unless someone does additional tests you've proven what we've been saying right along, that packing in a pot column has little effect once the column is up to temperature...

Too true! LOL

Perhaps 1 large wash that I can split into 2 portions would be a whole lot easier. The whole stopping, and restarting thing took a lot of time.

[DAD300]

I read that, that he got 86% without reflux...so he got a total of three plates and probably outperformed most thumpers!

[heartcut]

Packing will increase separation in a column without forced reflux, though the effect decreases as vapor speed increases (temperature differential to the inside column walls decreases). It's reflux caused by ambient cooling, but it works. Insulating the column would decrease the effect.
Propane burner heat can be metered by gas pressure taken before the orifice, with a low pressure (like 0-100"wc) gauge or a clear u-tube with water in it and a measuring tape fastened behind it (as a manometer). It will be interesting to see how much effect the no-forced-reflux packing has in real world distilling situations, all I've seen it in was little glass columns. Thanks.

[flyingdutchman]

I think part of the problem is that its just hard to say was the intial %ABV dead on.
See on the alcometer the division lines around 20% are real small so a little difference makes a big difference. I did read them as carefully as I could and I used a really good scientific thermometer (for temp correction)but there could have been as much as about 0.5% difference in either initial reading.
So for run my first reading was 18.7 (when temp corrected) but it could be off a smidgen either way
My second reading was 18.1 but it too could have been off just a little.

Then the third plate really starts to muddy things ( I didnt expect to be in that range) because once we get into that range a single plate only causes about 5 % ABV change.
I learned using the McCabe–Thiele method http://en.wikipedia.org/wiki/McCabe%E2% ... ele_method cause its easy to see the steps
I used the electronic version of it here and just plugged in the numbers for each step http://homedistiller.org/theory/theory/strong
So for my first run
from 18.7-> 68.7 is 1 plate;
then 68.7-84.8 is a 2nd plate (I had 84.5 just a tad under 2)

For my second run
18.1->68.2 is 1 plate
68.2->84.7 is 2nd plate
84.7->88.9 would be a 3rd (I had 86 a bit over 2)
So there is a difference but its only about 1.5% ABV

Insulating the column would decrease the effect

Now maybe if I didn't insulate it (DOH)
Now maybe if it wasn't surging ( I wish I knew why)
or maybe if I drove it slower
or maybe if I packed it better

but that's a lot of maybe's and I was hoping for something a whole lot more solid to hang my hat on

Ps that step from 68.2 to 84.7 seems a bit large which would throw off the next one and I see the reflux calculator puts a third plate at 88.2 but its a small discrepancy.

[HookLine]

Now maybe if I didn't insulate it

This.

Packing does nothing without reflux. Removing the insulation allows passive reflux from heat loss through the column walls.

Pointing a desk fan at the top of the packing is worth experimenting with.

Also, it is not just the immediate change in ABV that matters. Might only seem a small amount, but adding a little reflux slows the rate at which the ABV falls over the run. IOW, you delay the onset of tails and get more hearts.

[Prairiepiss]

I think you are just finding the same things I found when I first started. The difference between packed and not packed pot still. Is just not enough to even worry about. When I tested it. I got from .5% to as much as 5% ABV difference. But I was going off of different washes at different ABVs. Which lead to the 5% difference. Using the same wash at approx the same ABV. It was normally a .5% to 1% difference. Those tests were run on the same pot still. In the same conditions of a inside temp controlled room. Riser not insulated.

And personally I wouldn't consider a .5% or even a 1% ABV increase. Even worth messing with. And is why I have always posted that it isn't really worth it. Once the riser and packing gets up to temp. It does very little.

Now if we are talking about running it out in the cold. Or putting a fan on it. Well its no longer a pot still. You are forcing reflux. Just not using a water cooled condenser to do it. It would even change the output of an unpacked pot still riser.

I've said it before and I will continue to say it. At our scale a pot still is a pot still. Whether you out packing in it or place an expansion chamber in it. It's still a pot still. And you won't get enough of a difference to warrant doing it. If you want any of those things to work reasonably well at our scale. Forced reflux needs to be introduced. And then you end up with a reflux still.

Just my two nickles. And glad to see you got the results I expected.

[Odin]

I can run my iStill LM in potstill and pure mode. In potstill mode everything that's diluted at the top is being drawn off. With the packing in place (SPP), the potstill functionallity gives me two distillations. The advantage is that one run is enough on above 8% abv washes. For a lower than 8% wash, I prefer a 1.5 approach. Distill one part, add that to the remainder of the wash, now distill again and make cuts.

Odin.