Column Height Vs Diameter ratio

[diesel4ever]

The only things I see wrong with that equation is:

1. The person who wrote it needs to get laid or something and

2. Where in this equation does it prove that as column diameter increases so must column height?

If you have so much freaken time on your hands that you can actually calculate the CORRECT effective surface area of copper scrubbers or ceramic rings you should seriously consider a new hobby. I spent 10-15 seconds looking at this equation and can tell you it's severely flawed! Like I said before people tend to get too wrapped up on textbook theories that nothing ever gets accomplished. We are all here for one thing. Make great hooch with the least amount of effort.

Airhill I'm not disagreeing with that. You obviously have to change the heat output to make vapor speed a constant.

[kiwistiller]

1. The person who wrote it needs to get laid or something

No one is forcing you to participate in the discussion. If you don't like it, just don't join in No need to be obnoxious about it.

2. Where in this equation does it prove that as column diameter increases so must column height?

It doesn't. It shows that mass flow rate has an effect on HETP. Not sure if you've read the thread or are getting ideas confused, but the reason I think expressing design considerations in a ratio is wrong is because it implied just what you seem to think I believe - that a wider column needs to be taller. I don't think this. I think we should be talking design stuff in the simpler and less flawed unit of column height.
Cheers,
Kiwi

[airhill]

In practical terms the problems appear to be consistency of the packing media and the walls of the column. If we are talking columns under say 6" and assuming that the ratio of energy input is in proportion to the width of the column the wall effect is likely (guess) to be small in that a similar number of molecules will hit the walls. Packing could be a problem in that we use random packing and with its small cross section and relatively weak horizontal rigidity there could be a grip and gravity problem (? will it tend to sag in the middle leading to preferred flows of both vapour and condensate ie channeling).
Mr Nixon's book seems to indicate that on a 2" column the greatest thermal curve occurs in the lower half of the column (I assume this was when the column was in equilibrium and that he would have been running at ideal energy input for product take off) Although the top half appeared to be a 'reservoir' of hearts he seemed to think it was not quite that simple. I can only suspect that the top half was shifting in very small temperature increments.
What has that to do with design? To me it indicates that the bottom half does the coarse distilling and the top half does the fine seperation of the higher volatiles and that design considerations should concentrate more on that than ratios.

This is only a personal opinion and may bear no relation to reality

[diesel4ever]

Touche' Airhill. Touche'.

Finally some depth and bredth.

[Panache]

Hey Guys,

What a mass of wonderful information and discussion. I shall follow this with interest as it progresses.

However, as a complete newcomer to the hobby, does it help me decide on how much of my 42mm diameter column I need to pack?

It seems to me that with so many variables, each and all of which can change the calculated result, perhaps calculation is not the way forwards for me. A rough ratio system that allows me to decide on where to start is good - as is rad14701's rough guide of "Taking into consideration that the closer you get to 95% the more plates it takes to gain purity improvement we come up with the rough maximum of 4 - 5 HETP's worth of packed column... I use a figure of 2.5 column diameters equals 1 HETP as a rough approximation after running a range of column diameters, reflux ratios, and heat input..." At least these rough guidelines get those of us who are new to this moving in the right direction.

The theoretical discussion is very interesting, but we do need the practical approach as well.

Thanks again,

Panache

[kiwistiller]

1 metre to 1.5 metres would be a good height. This has nothing to do with your diameter in my books.

[Drosteo]

So.....
after reading this debate i am still confused.

I am planning on building a SS VM still with a 3" column. I was wishing to build with 3" rather than 2" as I am under the understanding that i will a faster output at the same purity? (please correct me if I am wrong)

In saying that am i going to achieve much of a difference in purity and or output with a 1m column vs a 1.5m vs 2m?

Apologies if this has already been answered but I was left a little confused and am relatively new to HD.

[olddog]

If you are building vm work out the height with a 24-1 ratio for the packed area + condenser and takeoff, it would end up around 8 foot high.

OD

[kiwistiller]

1-1.5, yes. 1.5-2... not so much. try plugging some parameters into the calculators on the parent site, and look at the results. The ratio doesn't really work for builds bigger than 2", which is one of the problems I have with it.

[rad14701]

Kiwistiller is right... The larger the column diameter, the lower within the range of ratios you can go... We have to remember that we are talking "home distillation" where house, garage, and shed ceilings are only so high and practicality starts coming into play... Anything over 4 - 5 feet of packed column starts becoming impractical, even for 3" or 4" copper...

[The Baker]

If you are building vm work out the height with a 24-1 ratio for the packed area + condenser and takeoff, it would end up around 8 foot high.

OD

That's what I will be building one day because I have 8 feet of 3 inch heavy copper tube and another piece longer than 1 foot that I can use for the condenser.
And I have the height available where I distill.

[rad14701]

I'm pretty sure you can get purity with less column height than 8 feet of 3 inch... The ratio of 24:1, or ratios in general, only work well with 2 inch copper... That is why there is a range rather than a single fixed ratio... The larger the diameter, the lower the ratio... Total packed column volume, and vapor volume and speed, come into play, amongst other criteria, and many different HETP calculations have attempted to prove this, so you can't use a specific ratio that works with every column diameter... With even the scientific experts not being able to agree on HETP calculations we are better off making height adjustments based on what works for our own set of particular circumstances... The ratios are simply a range to work within because we know that too short and too tall have diminishing results...

[Honest_Liberty]

For a column of a given diameter:....


Taking these facts into consideration:

There is no direct correlation between column diameterand HETP plate height
Once datum has been compiled a generic ratio can prove helpful in determining packed column height
Using generic ratios is not exacting science, but gets you in the ballpark with margin for error when any of the cparameters mentioned above is changed, within reason

Example:
2"/50mm column
2:1 reflux ratio
1500 watts power input
Stainless Steel scrubbers for packing

12"/30cm height (6:1) = 3.8 HETP's 4.24"/10.8cm tall and 90.4% ABV
24"/60cm height (12:1) = 6.6 HETP's 4.24"/10.8cm tall and 93.4% ABV
30"/76cm height (15:1) = 8 HETP's 4.24"/10.8cm tall and 93.9% ABV
36"/92cm height (18:1) = 9.5 HETP's 4.24"/10.8cm tall and 94.5% ABV
48"/120cm height (24:1) = 12.1 HETP's 4.24"/10.8cm tall and 94.9% ABV
60"/150cm height (30:1) = 14.9 HETP's 4.24"/10.8cm tall and 95.2% ABV

With these figures in mind, and considering how we can adjust our reflux ratio and heat input, we can change the number of plates, plate height, and purity. Therefore the column height:diameter ratio can be used to get a somewhat accurate estimation of whether the column is capable of performing within expectations or not.

With a 24" X 2" column, or 12:1 ratio, we can still get darn near 95% ABV by adjusting reflux ratio and heat input. The same goes for a 48" X 2" column. Now, where the top end comes in is with a 60" X 2" column where we can adjust past our maximum attainable ~95.6% ABV, meaning that we have more fudge factor built into the column. And at the lower end, a 12" column only has 3.8 HETP's (less than 5 HETP's) and therefore it is all but impossible to produce spirits in the ~95% ABV range with all the reflux ratio and heat input adjustments in the world unless you collect at less than one drip per second.

So, what does this all mean? It means that those speculative ratios get us close enough to be considered a reliable guideline. We must also consider that depending on which end of the column diameter extremes we go, the more skewed the accuracy will be. A 1.25"/32mm column will be thrown off more than a 3"/76mm column. So stating that anything below 12:1 won't allow for ~95% ABV and a ratio above 30:1 will have diminishing improvements in ABV is a relatively accurate statement.

Edited: To specify SS scrubbers as packing.

I read this whole thread. Kudos to you gentlemen for putting up with that arrogant lubavitcher.

I'm using copper scrubbers in my 2" column, fully packed.

I'm assuming the theoretical Max I can reach at 93.4% is with a reflux a device such as a dephlegmator. Is that correct? If I run a low wines wash at 40% and collect fairly slowly, I can't imagine I'm going to get to 93% with just 2' of packed copper scrubbers. I don't know what the 2:1 reflux ratio means. I'll have to go read but, I'm thinking that's the max WITH dephlegmator

[Yummyrum]

I don't know what the 2:1 reflux ratio means.

It means that 2/3 of the vapour that reaches the top will be condensed and returned back down the packing as reflux . The other 1/3 will come out as collected product .

A 2:1 reflux ratio is very low . Reflux ratios in the range 10:1 and even up to 20:1 are typically used when talking about making 95% or higher .

[Honest_Liberty]

Oh wow. So that would, if I understand this, require significant water usage that without a massive pond or swimming pool as a coolant sink, plus much longer drive times and energy on the still.

I'm wondering what I could grab by running at a decent place with 5' of copper scrubber packed column and no dephlegmator. I'm not sure if I see the value in producing a vodka considering all the time, when good stuff like kettle one is very accessible.

My concern is the waste of water unless I can figure a way to capture and recycle it.

Am I overestimating the water usage to make vodka or the increased energy requirements?

[Demy]

For neutral products in general you need adequate reflux ratios as said by yummy, playing with different ratios I also distill flavored products with a reflux column. For the amount of water you could think of recirculating by holding the water cold in various ways or by using a large container (which will take some time to heat up). It also depends on the efficiency of the condenser, the more efficient it is the less water is needed.

[still_stirrin]

Oh wow....Am I overestimating the water usage to make vodka or the increased energy requirements?

Not really. I think Yummyrum suggested that a reflux run (to a high purity) will consume 6 to 10 times the energy as a potstill run. So, it requires power and time investments.

Perhaps a different approach would be to lower the purity goals, especially if you’re just gonna make apple pie out of it anyway.
ss

[Honest_Liberty]

Oh wow....Am I overestimating the water usage to make vodka or the increased energy requirements?

Not really. I think Yummyrum suggested that a reflux run (to a high purity) will consume 6 to 10 times the energy as a potstill run. So, it requires power and time investments.

yikes! Considering I've pulled 86% at first drops on my last spirit run, I'm not sure that's the path I need to go. Once I get my brew room set up, at that point it may make sense

Perhaps a different approach would be to lower the purity goals, especially if you’re just gonna make apple pie out of it anyway.
ss

I don't plan on making apple pie. My cousin does that back East. Doesn't make anything but foreshot cuts. Apparently in the sticks folks love it but I wouldn't drink what he makes from what he told me.
I prefer to make great sipping spirits white, while I attempt to learn all grain and oak aging

[tiramisu]

So many rabbit holes so little time.
In some way, it is easier to begin with constraints.

i.e. I am willing to bring 1 30amp circuit to bear.
My ceiling height is < 8 feet.
I don't want to tend a still for more than 8 hours.
I don't have infinite money.


Now I can ask the question.
What is the appropriately sized column for my needs?

... Probably a 3" although 4 might be nicer but too much dollars.

[Honest_Liberty]

So many rabbit holes so little time.
In some way, it is easier to begin with constraints.

i.e. I am willing to bring 1 30amp circuit to bear.
My ceiling height is < 8 feet.
I don't want to tend a still for more than 8 hours.
I don't have infinite money.


Now I can ask the question.
What is the appropriately sized column for my needs?

... Probably a 3" although 4 might be nicer but too much dollars.

It's amazing how quick prices climb with each diameter increase.

[Honest_Liberty]

Pretty stoked! $60 shipped for a 2"x36" spool to bring my column height to 60"!

Now I'll be able to theoretically hit 95%!
Heck yes!

Question:

Let's say for bourbon practices though I don't want to use the dephlegmator to reflux.

Will that 5 ft of copper scrubber pack column vs my current 2ft give me extra ABV when I do my spirit run on a 40% low wine? I'm assuming I'm be able to pull off a few extra ABV. 2-3%?

[Honest_Liberty]

In practical terms the problems appear to be consistency of the packing media and the walls of the column. If we are talking columns under say 6" and assuming that the ratio of energy input is in proportion to the width of the column the wall effect is likely (guess) to be small in that a similar number of molecules will hit the walls. Packing could be a problem in that we use random packing and with its small cross section and relatively weak horizontal rigidity there could be a grip and gravity problem (? will it tend to sag in the middle leading to preferred flows of both vapour and condensate ie channeling).
Mr Nixon's book seems to indicate that on a 2" column the greatest thermal curve occurs in the lower half of the column (I assume this was when the column was in equilibrium and that he would have been running at ideal energy input for product take off) Although the top half appeared to be a 'reservoir' of hearts he seemed to think it was not quite that simple. I can only suspect that the top half was shifting in very small temperature increments.
What has that to do with design? To me it indicates that the bottom half does the coarse distilling and the top half does the fine seperation of the higher volatiles and that design considerations should concentrate more on that than ratios.

This is only a personal opinion and may bear no relation to reality

Could the 6" column be packed if we use a 6" screen in between the spool at the bottom ferrule where it meets the boiler? I'd have to use a bunch of packing on a 48" spool but it might be cheaper

[Bushman]

Packing is great on smaller diameter columns but as you increase the diameter the weight or load from the reflux process is heavier thus compressing the packing. That is why on commercial stills you see more plate type columns.

[Honest_Liberty]

Packing is great on smaller diameter columns but as you increase the diameter the weight or load from the reflux process is heavier thus compressing the packing. That is why on commercial stills you see more plate type columns.

Cool, thanks.

Will this work?
https://m.aliexpress.com/item/329717822 ... .jpg_.webp

[Bushman]

Bubble plates on a 6” diameter is probably a good way to go.

[Twisted Brick]

Question:

Let's say for bourbon practices though I don't want to use the dephlegmator to reflux.

Will that 5 ft of copper scrubber pack column vs my current 2ft give me extra ABV when I do my spirit run on a 40% low wine? I'm assuming I'm be able to pull off a few extra ABV. 2-3%?

If you are looking to make a rich, full-bodied bourbon, you don't want the extra ABV percentage. Doing this creates the need for more proofing down, which dilutes the flavor. Ideally, you want your newmake spirit to come off closer to barrel proof so you retain all the flavor you worked so hard for during mashing and fermentation.

[Honest_Liberty]

Question:

Let's say for bourbon practices though I don't want to use the dephlegmator to reflux.

Will that 5 ft of copper scrubber pack column vs my current 2ft give me extra ABV when I do my spirit run on a 40% low wine? I'm assuming I'm be able to pull off a few extra ABV. 2-3%?

If you are looking to make a rich, full-bodied bourbon, you don't want the extra ABV percentage. Doing this creates the need for more proofing down, which dilutes the flavor. Ideally, you want your newmake spirit to come off closer to barrel proof so you retain all the flavor you worked so hard for during mashing and fermentation.

With my 2' packed column, running slow at 40% low wines, I've started at 172 proof fairly consistently, but those are heads, so by the time they get to hearts I'm collecting at 160 proof. I'm just wondering if I don't run the dephlegmator and I have a 5' copper scrubber packed column, with 40% low wines, what folks may think it'll increase ABV by, if, at all

[Twisted Brick]

I’ve never run my (ss scrubber) packed column without the RC, but my guess on what you get in the way of passive reflux (maybe a third of a plate(?) until the packing gets hot then you get no reflux and add’l abv.

[Honest_Liberty]

I’ve never run my (ss scrubber) packed column without the RC, but my guess on what you get in the way of passive reflux (maybe a third of a plate(?) until the packing gets hot then you get no reflux and add’l abv.

Will the extra 3' help clean it up even more?

It seems that with pot stills, extra packed height offers nothing until refluxed? Am I understanding that correctly?

[Twisted Brick]

Right.

A pot still is just a direct line of vapor from the boiler to the condenser and does not need a tall column, packing or anything contributing to active refluxing. The only consideration for the length of the riser is so the product condenser can be positioned for convenience in collecting.