Max height for 2"column

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Merle
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Max height for 2"column

Post by Merle »

I have 3 pieces of stainless 2" diameter pipe with triclamp connections a 4 foot, 6 foot and a 10 foot. Should I use all 3 together and have a 20 foot column for making neutral or am I better off going shorter?
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Re: Max height for 2"column

Post by zed255 »

I'm forced to assume a reflux still, but you did not mention that detail. There will be a point of limited return past a height to diameter ratio of about 20:1, so with a 2" diameter the 4' spool you'd be past that mark already. A little added height may allow you to draw off product faster or may scrub it a little cleaner but I doubt going to extremes would be worth while. I'd use the 4' section or maybe to 6' section but no more IMHO.
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Re: Max height for 2"column

Post by still_stirrin »

Typically, the “rule of thumb” for column height to reach the azeotropic potential for reflux is 20 diameters. That would say that you’ll need 1 meter for a 2” ID column. So, your 48” (4 foot) spool should be all you need. But, you’ll need to pack all of it to get the proper height equivalent theoretical packing (HETP).

Also, different packing has different effectiveness. I use glass marbles in my 2” x 1 meter (insulated) column. But structured packing can be better, requiring less column height for the same heat input/vapor production rate. Copper mesh packing is good too, although more expensive. Stainless steel scrubbies works too and is less expensive than the copper stuff.

Basically, column height provides the adequate interaction between falling condensate and rising hot vapors to exchange heat and create the reflux necessary to purify the distillate progressing to the product outlet. But there is little advantage to an excessively tall column because flow velocity can become a factor to production (at the spout).

Your 6 foot (2” ID) spool would be somewhat wasted. And the 10 foot piece would simply become a configuration nightmare.
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edit - Thanks Zed, you beat me to the answer. My long-winded response fell into the trash bin.
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Re: Max height for 2"column

Post by Rrmuf »

There are much more experienced folks who's advice you should take over mine, but I am thinking it is a very very high column for any practical purposes. I think there are some downsides too:

1. You realize that for making neutral you will need to fill that column with packing right?
2. I would think the time it takes to bring that column into balance is increased considerably.

My neutrals are made in a roughly 4ft column with copper and stainless packing (and a reflux condenser) and produces 96% ABV neutral pretty consistently. Some people have higher ones to be sure but 20ft is way up there.

I look forward to the other comments this might draw.
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Re: Max height for 2"column

Post by Merle »

Yes it's a CM Still.Thank for the replys
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Re: Max height for 2"column

Post by Rrmuf »

zed255 wrote: Wed Sep 22, 2021 8:30 am I'm forced to assume a reflux still, but you did not mention that detail. There will be a point of limited return past a height to diameter ratio of about 20:1, so with a 2" diameter the 4' spool you'd be past that mark already. A little added height may allow you to draw off product faster or may scrub it a little cleaner but I doubt going to extremes would be worth while. I'd use the 4' section or maybe to 6' section but no more IMHO.
There you go: I knew I would learn something :-) 20:1 is a number I will remember. Thanks Zed, SS
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Re: Max height for 2"column

Post by still_stirrin »

Merle wrote: Wed Sep 22, 2021 8:35 am Yes it's a CM Still.Thank for the replys
How is the reflux condenser configured? Is it an old style “cross tube” condenser section?

The problem with CMs is that they are harder to manage the reflux ratio due to the relationship between the coolant water flow and the amount of reflux (condensed vapors {condensate} traveling back down the column).

It’ll work to give you a high purity, but can be tough to reach azeo. And the common thought is to increase the column height, but that isn’t really the problem with the design. It’s the way the vapors are condensed, or allowed to pass through to the product condenser. You really need full knock down power for the reflux condenser even at maximum heat input/vapor production in order to generate adequate reflux ratios.
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Re: Max height for 2"column

Post by OtisT »

I agree with the folks above, the 4’ section of packed 2” should be all you need. I was able to pull 95%+ from my 2” column packed with 40” of copper mesh. That was a VM, though a CM with proper/steady heat and cooling control should be able to reach the same purity. Be sure to insulate the packed section of your column. Otis
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Re: Max height for 2"column

Post by Saltbush Bill »

A CM will reach the same purity without any problem, just a little more fiddly to run if not the right design.
Do not fall into the trap of building one of those shitty old cross flow tube design things.
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Re: Max height for 2"column

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OtisT wrote: Wed Sep 22, 2021 9:03 am Be sure to insulate the packed section of your column. Otis
Tying to decide if the packed column needs to be insulated or not so I appreciate this comment. But was wondering…

1) How does insulation impact the amount of reflux in a 2” X 43” packed copper column?

While doing a spirit run I randomly wiped the uninsulated column down with a wet rag and noticed that output from the PC slowed down. As a result I wrapped wet rag around the entire column and found that the ABV increased about 10%. That effect was repeatable over and over as I experimented back and fourth with cooling the outside of the column with wet cotton cloth vs running with dry uninsulated column.

Column is currently insulated. Distilling in heated garage.

Seems like evaporative cooling increased the reflux.

Anyone seen this before?

My set up is …

58 L keg pot still
2” X 45” copper riser packed with copper scrub
48” Liebig condenser. 3/4 copper over 1/2 copper
4500 W element
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Re: Max height for 2"column

Post by howie »

i agree that a 4'/1.2m column would be fine, as otis says.
dancing, i started distilling in winter, i noticed that cold winds gusting around the still affected output.
i suppose suddenly wiping the column with a wet rag would do the same, ie cool the vapour/condensate inside.
it's now insulated so i don't have any external temp fluctuations.
bearing in mind there is only about a 2C difference in the top fraction and a slightly lower fraction, i don't want to waste the 40-50 mins i spent getting the column to EQ to a gust of cold wind (or a wet rag :) )
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Re: Max height for 2"column

Post by Yummyrum »

Dancing4dan wrote: Mon Oct 25, 2021 9:20 am
OtisT wrote: Wed Sep 22, 2021 9:03 am Be sure to insulate the packed section of your column. Otis
Tying to decide if the packed column needs to be insulated or not so I appreciate this comment. But was wondering…

1) How does insulation impact the amount of reflux in a 2” X 43” packed copper column?

While doing a spirit run I randomly wiped the uninsulated column down with a wet rag and noticed that output from the PC slowed down. As a result I wrapped wet rag around the entire column and found that the ABV increased about 10%. That effect was repeatable over and over as I experimented back and fourth with cooling the outside of the column with wet cotton cloth vs running with dry uninsulated column.

Column is currently insulated. Distilling in heated garage.

Seems like evaporative cooling increased the reflux.

Anyone seen this before?

My set up is …

58 L keg pot still
2” X 45” copper riser packed with copper scrub
48” Liebig condenser. 3/4 copper over 1/2 copper
4500 W element
PWM
Dancing4dan .
From what you have described , it sounds like your coolant management head is not capable of coping with the amount of power you are putting into the boiler .

You did not describe what kind of CM head you have.

An increase of 10% abv by applying a cool rag backs up my reasoning . With just under 96%ABV (being the most you can theoretically get) , that suggests that you are running at 86% or less .
A reflux still should easily do better…. Especially seeing as yours is 48” packed .

A CM head should be capable of 100% reflux at the maximum power you can put into the boiler before the column floods .

If you have full flow of water through it and it still is letting product come out , then it is not an efficient CM head . If putting a cool rag on it has more effect than full coolant flow through it then it is not an efficient CM head .

So I think your cool rag is showing up a serious flaw in your still .
A fully insulated reflux still can easily run 100% reflux .

As mentioned , the insulation simply prevents breezes from interfering with the column equilibrium .
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Re: Max height for 2"column

Post by Saltbush Bill »

Gave this some though on and off today and pretty much came to the same conclusion as Yummy,
Your still is not working efficiently, my guess is its not getting enough reflux, the wet rag is increasing the amount of reflux, hence the increase in ABV.
As has already been said, you cant really call a still that cant do better that 86 % much of a reflux still......its more a pot still with a little reflux.
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Re: Max height for 2"column

Post by Andrew_90 »

What constitutes the "column". I have a sight glass above the column and before the T Piece on a CCVM. Is the sight glass and or the T Piece considered to be part of the column?
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Re: Max height for 2"column

Post by RC Al »

Andrew, every inch that has packing
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Re: Max height for 2"column

Post by Yummyrum »

RC Al wrote: Tue Oct 26, 2021 2:49 am Andrew, every inch that has packing
Good points Andrew and Arsey . :thumbup:

It’s only that packed section that counts … the rest is Bragg’n rites :ewink:
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Re: Max height for 2"column

Post by Rrmuf »

Super interested in this conversation: Stillerboy did give me a great hint once, that being adding some compressed pure SS scrubbies within my RC (water-jacketed type) and that helped give me a further 4-5% purity on its own! It seems to ensure good conductivity from the cool water throughout the RC column cavity.

The other key learnings for me:

1. insulation helps keep the column stable (and speeds up warm up)
2. The RC needs a very constant coolant (temp and flow rate), controlled by a fine-tunable (needle) valve. How to achieve this is very situational, but I can describe what works for me if anyone wants. BL: there is some forgiveness in the actual water temp but NOT in keeping it constant.
3. Max power and coolant flow is determined by alternately increasing both, getting to 100% reflux and 0 outtake flow until you can't any more. Then you can increase power a bit to achieve a desired ABV and flow. At that point, it's a trade off.

At that point, I find the still does its thing really well pretty much without any intervention except changing out jars. I keep a thermometer in the RC water supply to provide early warning of any subtle temp change and can quickly compensate for that.
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Re: Max height for 2"column

Post by Bushman »

My 2” x 4’ VM would produce 96% on an 11 gallon charge but would take anywhere from 12-17 hours to run. With my 4” x 50” CM I can reach 92-93% in 3.5 hours. Both stills are packed completely with my homemade wire mesh. Know way would I go higher that 48” on a 2” column. Another consideration is support for a column that is too high plus where you would run something that tall.
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Re: Max height for 2"column

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Rrmuf wrote: Tue Oct 26, 2021 3:39 am 3. Max power and coolant flow is determined by alternately increasing both, getting to 100% reflux and 0 outtake flow until you can't any more. Then you can increase power a bit to achieve a desired ABV and flow. At that point, it's a trade off.
Yes and no.. if you have excess cooling capacity, 5000w is wayyy to much to run a 2" at, getting 95 and getting a clean product are two different things. :thumbup:
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Re: Max height for 2"column

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RC Al wrote: Tue Oct 26, 2021 4:46 am
Rrmuf wrote: Tue Oct 26, 2021 3:39 am 3. Max power and coolant flow is determined by alternately increasing both, getting to 100% reflux and 0 outtake flow until you can't any more. Then you can increase power a bit to achieve a desired ABV and flow. At that point, it's a trade off.
Yes and no.. if you have excess cooling capacity, 5000w is wayyy to much to run a 2" at, getting 95 and getting a clean product are two different things. :thumbup:
I guess I don't ever get there, since I only run a 1700w heater. I do feel I get a clean neutral @96% but I am interested in how you see the two as countering each other. I *can* see how pushing too much power would make a less clean product but I would suspect the ABV would also suffer atleast a bit.
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Re: Max height for 2"column

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Rrmuf wrote: Tue Oct 26, 2021 4:51 am I guess I don't ever get there, since I only run a 1700w heater. I do feel I get a clean neutral @96% but I am interested in how you see the two as countering each other. I *can* see how pushing too much power would make a less clean product but I would suspect the ABV would also suffer atleast a bit.
This caused me problems on my first run on my CCVM. I found that I could pull 96% at up to 1.5L / hour, but it just pushed tails into that remaining 5%. Throttling back to around 700ml / hour vastly improved the quality...

...but I'm far from being able to claim any real experience on it yet.
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Re: Max height for 2"column

Post by bluefish_dist »

I know I am in a minority, but I believe taller is better. Based on what Odin has posted, 15 trays is minimum for azeo and more up to 40 makes it easier. My testing agrees with this. I think most here who claim azeo can not truly make it. They simply don’t have the tools to measure the difference between 189.8 and 191 proof. Nor does it really matter as they are not bound by any laws for production.

Since scrubbies hetp is 4”, 15 trays is 60” or 5 ft of packing. I found 20-25 was a good compromise of space and purity. So that would be closer to 7 ft of packing. I could hit 190.3, 190.4 with 6 ft of packing. With 8ft I could do a solid 190.5. Tried many different packings and columns in search of faster, higher proof production. Scrubbies seemed to work best and more height was always the answer. Azeo at any decent takeoff rate is hard to do. Probably harder than making whiskey.
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Re: Max height for 2"column

Post by shadylane »

Dancing4dan wrote: Mon Oct 25, 2021 9:20 am
OtisT wrote: Wed Sep 22, 2021 9:03 am Be sure to insulate the packed section of your column. Otis
Tying to decide if the packed column needs to be insulated or not so I appreciate this comment. But was wondering…

1) How does insulation impact the amount of reflux in a 2” X 43” packed copper column?

You want the column to be insulated.
The taller the column the more important insulation becomes.
The column works best when all the reflux comes from the RC
That way the reflux gets to rain down the full height of the column.
Instead of trickling down the walls from passive reflux. :wink:

posting with blue fish
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Re: Max height for 2"column

Post by bluefish_dist »

shadylane wrote: Tue Oct 26, 2021 10:23 am
Dancing4dan wrote: Mon Oct 25, 2021 9:20 am
OtisT wrote: Wed Sep 22, 2021 9:03 am Be sure to insulate the packed section of your column. Otis
Tying to decide if the packed column needs to be insulated or not so I appreciate this comment. But was wondering…

1) How does insulation impact the amount of reflux in a 2” X 43” packed copper column?

You want the column to be insulated.
The taller the column the more important insulation becomes.
The column works best when all the reflux comes from the RC
That way the reflux gets to rain down the full height of the column.
Instead of trickling down the walls from passive reflux. :wink:

posting with blue fish
I would also add, level the column so it’s vertical. If it’s at an angle it won’t work as well. I had a bracket on the wall half way up to support the column and keep it straight.
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Re: Max height for 2"column

Post by Setsumi »

NormandieStill wrote: Tue Oct 26, 2021 10:01 am
Rrmuf wrote: Tue Oct 26, 2021 4:51 am I guess I don't ever get there, since I only run a 1700w heater. I do feel I get a clean neutral @96% but I am interested in how you see the two as countering each other. I *can* see how pushing too much power would make a less clean product but I would suspect the ABV would also suffer atleast a bit.
This caused me problems on my first run on my CCVM. I found that I could pull 96% at up to 1.5L / hour, but it just pushed tails into that remaining 5%. Throttling back to around 700ml / hour vastly improved the quality...

...but I'm far from being able to claim any real experience on it yet.
Yes, take off speed is a key variable to minimize smearing. Slower take off with enough reflux for me.
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Re: Max height for 2"column

Post by Setsumi »

bluefish_dist wrote: Tue Oct 26, 2021 10:14 am I know I am in a minority, but I believe taller is better. Based on what Odin has posted, 15 trays is minimum for azeo and more up to 40 makes it easier. My testing agrees with this. I think most here who claim azeo can not truly make it. They simply don’t have the tools to measure the difference between 189.8 and 191 proof. Nor does it really matter as they are not bound by any laws for production.

Since scrubbies hetp is 4”, 15 trays is 60” or 5 ft of packing. I found 20-25 was a good compromise of space and purity. So that would be closer to 7 ft of packing. I could hit 190.3, 190.4 with 6 ft of packing. With 8ft I could do a solid 190.5. Tried many different packings and columns in search of faster, higher proof production. Scrubbies seemed to work best and more height was always the answer. Azeo at any decent takeoff rate is hard to do. Probably harder than making whiskey.
Agree. More packing for neutral. But no one commented on strips and spirit runs to make good neutral... maybe most only run that in any case but in my neck of woods most new distillers ignor this.... it even makes for good wiskey on a flute.
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Re: Max height for 2"column

Post by Yummyrum »

bluefish_dist wrote: Tue Oct 26, 2021 10:28 am I would also add, level the column so it’s vertical. If it’s at an angle it won’t work as well. I had a bracket on the wall half way up to support the column and keep it straight.
I would disagree :ewink:

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Re: Max height for 2"column

Post by Saltbush Bill »

Setsumi wrote: Tue Oct 26, 2021 11:49 am But no one commented on strips and spirit runs to make good neutral... maybe most only run that in any case but in my neck of woods most new distillers ignor this..
I thought it was pretty much standard procedure to run low wines rather than wash if your trying to make quality neutral.
Anyone who spends a bit of time reading before jumping into reflux stilling should know that.
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Re: Max height for 2"column

Post by Setsumi »

Saltbush Bill wrote: Tue Oct 26, 2021 12:09 pm
Setsumi wrote: Tue Oct 26, 2021 11:49 am But no one commented on strips and spirit runs to make good neutral... maybe most only run that in any case but in my neck of woods most new distillers ignor this..
I thought it was pretty much standard procedure to run low wines rather than wash if your trying to make quality neutral.
Anyone who spends a bit of time reading before jumping into reflux stilling should know that.
Agree, but I bet if you poll new distillers (say 2 years active) most will be running fresh.
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Re: Max height for 2"column

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RC Al wrote: Tue Oct 26, 2021 2:49 am Andrew, every inch that has packing
Thanks.
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