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diesel4ever wrote:1. The person who wrote it needs to get laid or something

diesel4ever wrote:2. Where in this equation does it prove that as column diameter increases so must column height?

olddog wrote: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

rad14701 wrote: ↑Mon May 24, 2010 8:26 pm
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.

Honest_Liberty wrote: ↑Mon Feb 15, 2021 4:14 pm I don't know what the 2:1 reflux ratio means.

Honest_Liberty wrote: ↑Tue Feb 16, 2021 7:14 am Oh wow....Am I overestimating the water usage to make vodka or the increased energy requirements?

still_stirrin wrote: ↑Tue Feb 16, 2021 7:33 am

Honest_Liberty wrote: ↑Tue Feb 16, 2021 7:14 am 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

tiramisu wrote: ↑Tue Feb 16, 2021 8:25 am 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.

airhill wrote: ↑Tue Jun 22, 2010 4:15 pm 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

Bushman wrote: ↑Tue Feb 23, 2021 7:43 am 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 wrote: ↑Thu Feb 18, 2021 6:13 pm
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%?

Twisted Brick wrote: ↑Tue Feb 23, 2021 10:52 am

Honest_Liberty wrote: ↑Thu Feb 18, 2021 6:13 pm
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.

Twisted Brick wrote: ↑Tue Feb 23, 2021 5:06 pm 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.