Multi columned reflux still

[SuperCamel]

Hi,

I have a stove top still and I'm not entirely impressed with it. It works alright but it could be better. I would really like to make a taller column to get a higher quality product but since my stove has an exhaust fan over it the column height is limited to about 300mm. My solution is to have multiple short columns connected in series. Once the vapour reaches the top of the first column it goes back down to the bottom of the next column and so on. If there are 4x 300mm columns the vapour would travel through 1200mm of packing. So therefore the resulting product should be fantastic, right??

Are there any obvious flaws in this design?

[tafinaf]

A column must be an uninterrupted vertical, ehm, column to be of any use, sorry.

[SuperCamel]

Are you saying that it would be no different to having a single 300mm column? I understand that it probably wouldn't be as good as having a single 1200mm column, but surely it must be a huge improvement on a single 300mm column.

[Chiller]

Hmm, that would be interesting to think about SuperCamel - I probably would have had such a notion not two weeks ago ! The problem with multiple 'connected' small columns is that a gradient must be formed when running the still (especially in full reflux), that is, a gradient of different boiling-pointed fluids (the constituents of your charge) - this isn't possible if the distillate 'goes back down' to the bottom of the next column, because all of the alcohols will just get mixed up once they drop down, hence it is no more use than a single 300mm - additionally, it would be extremely inefficient (and not to mention slow) due to the poor heat transfer between horizontally arranged columns (vapour flows upward in our case). Sorry to break your thunder Camel

I'd wanted a stove-top originally (I mean very-very originally) but found out it just wasn't practical or effective - if you have height issues then a wider column could help, but I don't really advise more than 2" if it's your first as its quite difficult to work with, and expensive so I'd say your best bet is to just go with a hotplate (with another plate or something between it and the boiler to reduce temp fluctuations) on the floor, or an internal element - these are quite hard to get your head round, but not too expensive, and they make a good read

Hope that helps!

Chiller

[sthudium]

Chiller explained why the proposed method for short, multiple columns doesn't work. In that scheme, the vapor from the top of one short column is run down to the bottom of the next column. But what would happen, if instead of running the vapor from one short column to the next, we ran the 1/2 of the reflux from one short column to the next. Would that result in increasing ABV and purity?

[airhill]

Without the vapour flow routes and liquid return lines it is difficult to see what you are proposing

[Prairiepiss]

Without the vapour flow routes and liquid return lines it is difficult to see what you are proposing

It's there you just need to know what your looking at.

I'm assuming you theory here is. The collection from the first column on the left is dumped in the the next column increasing the ABV of the take off that goes to the next. And so on. But as I see it is you may end up as a stronger ABV takeoff. But it will have flavors still present because you still are feeding the last column with the boiler. And what gains you will have will be minimal. You would be better off with 4 thumpers in line. Just my thoughts.

[WalkingWolf]

Hi,

I have a stove top still and I'm not entirely impressed with it. It works alright but it could be better. I would really like to make a taller column to get a higher quality product but since my stove has an exhaust fan over it the column height is limited to about 300mm.

How wide past the stove is the vent hood?

When I ran a stove-top rig I had the same thoughts and had planned on a 45 right off the lid until it cleared the hood then 45 back to vertical. If you offset the opening on the pot lid you could turn the lid and use the weight of the pot (and liquid) to help compensate for the "weight" of the still. It would still be advisable to have some support under the taller vertical portion of the still.

If you haven't purchased copper yet the DWV is considerably lighter than any of the other grades of copper.

[sthudium]

But it will have flavors still present because you still are feeding the last column with the boiler. And what gains you will have will be minimal. You would be better off with 4 thumpers in line. Just my thoughts.

Thanks Mr P. Your response has uncovered another weakness of my newbiness.

The mimimal gain that you predict, certainly makes this concept foolhardy.

[airhill]

Without the vapour flow routes and liquid return lines it is difficult to see what you are proposing

It's there you just need to know what your looking at.

I'm assuming you theory here is. The collection from the first column on the left is dumped in the the next column increasing the ABV of the take off that goes to the next. And so on. But as I see it is you may end up as a stronger ABV takeoff. But it will have flavors still present because you still are feeding the last column with the boiler. And what gains you will have will be minimal. You would be better off with 4 thumpers in line. Just my thoughts.

I had made the assumption that the manifold was lying across the boiler top and was being fed by vapour from the boiler under the product column with only column 1 open to the manifold the rest dumping the excess fluid back into the manifold by say liquid locks.

[Ayay]

Maybe this arrangement?

Vapours go into column 1. Columns 2 and 3 are thumpers heated in the boiler but they may work as thumpers with their bases out of the boiler. Column 4 allows the water to go back into the boiler while the final product is delivered.

I can't see columns 2 and 3 doing any more than passing it along and they don't need their own condensers either. I can only see columns 1 and 4 doing any good...the vapours have to go in one end, and the waters have to get back into the boiler.

It can't work like a single column because a single packed column relies on vapours going up the whole length at the same time as liquids going down the whole length. Column 1 will do it if it has a needle valve, columns 2 and 3 sort-of, but column 4 won't have vapours going up.

Better to run a single short column as a pot still.

[astronomical]

I had wondered how ths could be done too. I came up with this terrible idea a while back. I intended to stagger a bunch of 1.5" and make it so it was easier for the vapor to go through the condensate than through the liquid traps. I don't know enough about liquid dynamics to know how the traps would function. I was thinking if i used 1/2" for the vapor pipes and 3/8" for the trap returns it would work. But, what do I know. I have no idea how effective each "thumper" would be either. If I made the design i was going to make about 20 small chambers. only the final chamber has a condenser. I'm not suggesting this in any way shape or form. I don't know enough. I'd sure like to know what to do to optimize this though. I'd also like and informed opinion on what i could expect for 20 thumpers in a row in 6"x1.5" pipes. I'd imagine that i may have to push the heat to the point that im flooding the first few to get the final ones to actually bubble. I really dont know.

Don't bash me for this. This is a completely untested design and I have no idea what it would do. Im a novice.

If it were plausible that it would work I would spiral them in as close a cluster as possible. It would keep the weight centered and concentrate a lot of lost heat back into itself

I guess I may need slightly larger pipe and bigger return lines so I can throw a lot of heat without flooding it, but, I want to know why this won't work. Unless I get a solid readon, I'm building it

[sthudium]

Astronomical,

I was considering something like that could be done, sorta converting LWTCS' inline thump tower from a vertical in-line to a horizontal in-line. I'm sure the thumper sizes are way out of line, but the idea is that the thumpers get smaller as you move away from the boiler. To paraphrase one of the experts, just because this idea is new to me, it is not new. So please be kind.

[heartcut]

There's a lot of commercial and industrial distillation towers that pipe vapor from the top of the 1st column to close to the bottom of the second, with a liquid return at the bottom of the 2nd back to the boiler or to feints. OD did something similar in a home size rig. Should work, but you might have some R&D to get through.

[Prairiepiss]

I'm not really seeing the point in all of this? If your going to go through the trouble of all this. Why not just build a flute or something? I thought the purpose was to save space? Looks to me like the ideas being thrown out will take up more room then a simple flute. Or any other still for that mater. So I'm asking what is the point of these ideas? What are you trying to accomplish?

[astronomical]

I'm not really seeing the point in all of this? If your going to go through the trouble of all this. Why not just build a flute or something? I thought the purpose was to save space? Looks to me like the ideas being thrown out will take up more room then a simple flute. Or any other still for that mater. So I'm asking what is the point of these ideas? What are you trying to accomplish?

I completely agree that if you need large thumpers (as sthudium suggested) that it wouldn't be very economical or compact. You would also run out of reflux/distillate to fill the thumpers unless you had a giant boiler or very low fill heights (which would render the large size obsolete?i think?)

My idea stands under 24" tall with 6 chambers and could be shorter. Probably around 16" to 18" when accouning for some clearence on the first riser. I just realized that I accidentally did 2x12" chambers in the old design specs. Regardless, each additional chamber will only raise the height the addition of 2 downcomer diameters. Since I used 3/4" it will be about 1.5-2" addition in height for each chamber, regardless of how tall they are. The intent was that it would be easier to build than a flute and more compact. I just need to find out if a bunch of 2"x6" chambers will work. It will also be much cheaper than a flute. I priced out my whole build at less than $100. Building a bunch of identical chambers would be pretty damn easy IMO. I was thinking of lining them up like Peruvian flute, but, all in equal length (but staggered in the same sort of way). This would be to minimize heat loss and keep it more compact. Id like to try and make a honecomb/peruv.flute type cluter of six 2X6" chambers (as a test).

I guess the real question is how will a thumper (if we can still call it that) perform in such a small size. I guess my design is really more a seried of bubble caps that are modular and connected externally.

@Sthudium

Your design is different in one large way (*and some small ones). You don't have a system which can cycle in full reflux. Anything that ever passes the final thumper must be taken as product.

[airhill]

Here is the original drawing (slightly modified). At this point it will not work. The idea is that the vapours flowing along the manifold act as a heat exchanger and secondary boiler enricher. Column 2 is dumping excess into the manifold columns 3 and 4 are dumping into the column before.
Please note it will not work as shown and is only an idea.

[sthudium]

As I said in my earlier post, I am sure my thumpers are way too big. I was thinking that the thumpers would retain the charge from earlier runs and would be heated by being housed in a BBQ. This might be fun for some folks. Anyway, it's just an out-of-the-box thought game (or maybe a fantasy diversion).

P.S. Some BBQ's accept water for smoking the meat.

[Arphaxad]

I think it's fun to try and come with different idea's it helps the pro's know if we are getting the basics. Because some idea's just simple won't work.

It seems that the nessesary component in any effective reflux design is a way for the vapors to equalize and in essence push the heavier vapors down the column, then to start the take off and increase the take off speed as high as you can go without disrupting that equalized column to much.

Is this correct? I know we talk about alcohol vapors rising but if you had total knock down power at your condenser wouldn't the alcohol vapor eventually start filling the top of the column and pushing back down if you weren't taking anything off, or would that require a pressurized system which is a no no?

[rad14701]

I'll go out on a limb here and potentially cause folks to get all riled up... Multi-column stills have pretty much been proven to not be efficient... The topic arises several times a year in these forums... If there was a simple way to make the concept work it would already have been discovered and be in use today... The crux of the matter is that people keep coming up with multi-column designs which, essentially, do little more than a thump tower or a plated column design... What are you accomplishing with a multi-column design that isn't accomplished with a thump-tower...??? Height issues can be mitigated by simply utilizing shorter thumper sections... The only real difference is using extra height and structured packing to promote additional HETP"s which these other designs provide in a more efficient manner and without the added weight and expense...

Round and round we go...

[airhill]

I think it's fun to try and come with different idea's it helps the pro's know if we are getting the basics. Because some idea's just simple won't work.

It seems that the nessesary component in any effective reflux design is a way for the vapors to equalize and in essence push the heavier vapors down the column, then to start the take off and increase the take off speed as high as you can go without disrupting that equalized column to much.

Is this correct? I know we talk about alcohol vapors rising but if you had total knock down power at your condenser wouldn't the alcohol vapor eventually start filling the top of the column and pushing back down if you weren't taking anything off, or would that require a pressurized system which is a no no?

Vapours only rise liquid descends. The column relies on phase change and a temperature gradient to allow it to happen. Reflux condensers are designed to knock down everything as liquid (excepting CM's on product takeoff).
The reason multi columns are difficult, aside from a complex expensive build, is dealing with the excess liquid and controlling the vapour and liquid flow and energy requirements. They are not thumpers which are basically an extra one plate (well possibly one and a bit) stage. You can pull neutral off a fairly short column, albeit very slowly you can't do it off a thumper.

Edit
'Vapours only rise liquid descends.' That is an inexact statement but correct in context of the quoted post.

[heartcut]

Multi column stlls are fairly common in the commercial arena:
http://bavarianbrewerytech.com/potstill ... allery.htm" onclick="window.open(this.href);return false;" rel="nofollow
I've worked on quite a few multi column distillation processes in refineries and chemical plants, too, but their products don't taste as good.
Whether or not this can work for a home distiller might be a question, but there's no doubt that the concept works.

[Lynx_Gen]

I have an exhaust hood over my stove.. its attached up above it.. i still have like 34 or 38 inch colum (Packing, condensor etc included) but not including the 10-12 inch tall boiler. theres still room for me to hold my breath and stick my hed up there for quick peek into it.. lol..

the trick i found is this... my stove isnt heavy at all... i just slide it out a few inches so the column clears the hood..

~L~

[RumBrewer]

I'll go out on a limb here and potentially cause folks to get all riled up...
Round and round we go...

Them's fightn words mister! Put up yer paws we gonna box!



That being said, how much power would it take to run 4 thumpers? You'd need a MASSIVE amount of heat?

[emptyglass]

the trick i found is this... my stove isnt heavy at all... i just slide it out a few inches so the column clears the hood..

~L~

Now thats thinking outside the box...or, umm, the exahust hood

Why jump the wall, when you can go through the gate.

In some cases, it might be easier to do a rangehood mod, than to redisign a still.

[LWTCS]

That being said, how much power would it take to run 4 thumpers? You'd need a MASSIVE amount of heat?

That depends on the thumper size. As my 100% reflux mode progresses toward the optimal time to collect, my system can tolerate less power with little to no impact on the collection stream's ability to remain completely unbroken. The bulk purity liquid level at the top two chambers is so proofy that I only need enough heat to evaporate 90+ abv. With excellent thermal transfer, the rising boiler temps make a solid contribution at driving the system.
Though I have not factored energy used to get my rig to this state of equalibrium.

[ozone39]

or a ponu....

[Doxxx]

there are comercial stills that do this but you need vapor lock down comers on the aditional columns or collector vessels at the bottom that collect semi distiled spirit and can later be rerun as lowwines also dephalgamator at the top of each column Cooling managment style would proberably be easiest

see the picture

the only problem is the pressure cant exceed the back pressure of the vapor locks. if you wanted you could run them back into the boiler

[myles]

You can build side column stills - there are plenty of examples. However if I read this correctly the problem is the head height above the stove. If you have enough height off to the side of the range hood then why not just do this. Use the boiler to feed a thumper and just put as tall a column as you can manage on the thumper.

I used to run this thumper from a floor mounted boiler, but the principle is the same.



Just go out sideways under the hood to the thumper and then put the column on the thumper. If you use a thumper about 1/2 the size as your boiler then you are unlikely to overfill it. If in doubt just make the thumper the same size as the boiler. In reality all you are doing is using you 'pot on the stove' as a remote heat source for the real boiler - the thumper.

[myles]

I have different reasons for doing so, but I am actually considering this as a poosible option with my own rig to maximise the column height: