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hi guys, i'm at it again (oh no, i hear ). this time i am considering making a new pot still to run my soon to be ready 75 litres of plum wash. i was looking around for ideas and was looking into thumpers. since i have a good amount of 2" and 3" stainless tubing lying around for making my vm still i thought i could come up with something a little different:-
what i came up with was this. a pot still with an internal thumper, a sort of "thumper column (don't ask )

the idea is to use a short 12" -14" column made with 3"stainless tubing, and have a built in thumper made out of 2" stainless tubing, sitting inside the outer tube. the thumper will have an overflow tube fitted (to prevent liquid spouting out of the condenser, i was thinking straight back into the boiler below the liquid line to prevent vapour going the wrong way. it's really simple to construct and i allready have all the materials lying around. also, as my vm still's head can be removed, i could construct this as a separate head for my existing column.

one advantage i can see is the thumper will come up to temperature quicker than an external unit, also, you could construct it to run without liquid and botanicals could be placed inside (for the gin lovers out there).

what do you think?. maybe i'm sampling a little more product than i should be

I don't think this will work well... in a thumper the temp slowly rises until it reaches vapor boiling point and it gets a second distillation. In this, the heat inside the still will reach the boiling point of ethanol. at this stage, the water, too will be heated to ethanol's boiling point. This in my mind would mean the ethanol vapor would bubble straight through the water and do nothing? The thumper needs to be heated by the vapor going through the water only, in my mind.

On the other hand I could just be wrong... but i think that the thumper compartment would be heated too much. The water will not evaporate, but the vapor will not condense and re-evaporate, it will just bubble through because of the heat inside the still.

Look on the parent site following these headings Equipment->Making a Still->Designs & Plans->Thumpers, Doublers, and Slobber Boxes. There's some helpful info there. One of the things it says there is that typically the incoming distillate has more than enough heat to run a second distillation. Going from that and some of my experience, I think that the heat loss of a thumper is important to the doubler reaching it's equilibrium. If you put the thumper in the column it's effectively insulating it from heat loss which is definately going to affect how it works. I'm also wondering whether you'd be able to size a thumper in your column large enough for it to be effective. It's an interesting idea. While I'm not inclined to build one like that myself I'm curious about how it moight work.

Thumper inlet pipe and overflow will be at same vapour pressure so vapour will not bubble through tube.
Vapour will simply pass throught the overflow to the stillhead directly.

it will work...
only change needed is on your overflow, use a J shaped tube to make a drain pipe and a water lock under thumper.

the steam temp inside the pot will be equal to % mixture of volatile liquid and water at the time therefore the temp of thumper will not reach 100c.
also the liquid contained in thumper will not exceed its boiling point based on volitile % of liquid in it.

the rule for steam is that as it passes thru water it will condense and re evaporate at a 1:1 energy ratio and the liquid with a higher % volitility will boil of first


cheers

you have seem to over look the back pressure that it will make
my still has a 50mm J tube in it and i have noticed it builds up a fair bit of pressure and you want to go for one that is all most 300mm long?
you would blow your self up

Adverse Effects wrote: you have seem to over look the back pressure that it will make
my still has a 50mm J tube in it and i have noticed it builds up a fair bit of pressure and you want to go for one that is all most 300mm long?
you would blow your self up

i will asume you are comenting on my reply..



the J tube has nothing to do with back pressure..

cheers..

I don't think you'd need an overflow tube if your thumper is proportioned right.

If you have to have an overflow tube on this, you might want the depth of liquid to be overcome in the j-bend to be greater than that of the inlet tube or it might be the path of least resistance to the incoming vapor and become the inlet tube.

I've run a thumper before where the inlet tube was submerged somewhere between 200 and 250mm. The inlet tube was 3/8" copper tube. It didn't blow up. My current thumper has at least three feet of tube that is lower than the level of the thumper, although the depth of the liquid in the thumper is only 2". A little different situation but no problems there either.

decoy wrote:i will asume you are comenting on my reply..


cheers..

hmm no i was referring to the original post and pic

but as for your one i would not have any more than 50mm in the hight difference of what you have marked in your drawing

50mm of water is a lot of pressure i didn't realize this till i built my still

decoy wrote: i will asume you are comenting on my reply..

the J tube has nothing to do with back pressure..
cheers..

Funny was just discussing this last night with Pintoshine via the live chat, was looking at building a thumper with a built in overflow that will drain back to the pot.
never read this post, but came to the same conclusion.

Nice solution! Possibly....

Question to ponder: with the thumper sitting right on the boiler, it will run much hotter than a separate thumper would, so I wonder if the vapors won't simply shoot through the water/liquid(which will be at the same temperature as the boiler itself) without further separation, which would negate the reason for the thumper. Anyone have actual, hands-on experience with this setup? I like it's simplicity and elegance, and am tempted...

I'm pretty sure that a certain amount of heat loss is fairly important to the effectiveness of a thumper. The incoming vapor on a thumper typically carries with it much more heat than is needed for the second distillation. This means that some of this probably needs to be sunk somewhere. Otherwise it's like running a stripping run with as much heat as you can put to it. You'll lose some purity. If all that is true, the last place you'd want to put a thumper is inside your column where it will essentially have no heat loss at all.

This is a external version i have been working on for a bit..
only thing i havent decided wether its technicly a doubler or that im just adding 1 plate to the still sort of does the same thing,
i have been following a few discussions as to what goes into a doubler or thumper at the start.



with this design you will get a small % of reflux return from the lyne arm, but i belive it will be just as affective as a thumper.

cheers.

decoy wrote:only thing i havent decided wether its technicly a doubler or that im just adding 1 plate to the still ...

By definition a doubler is an attempt to add another plate of distillation. So if your doubler is an integral part of your still you've added a plate to your still. So no matter what you decide you're probably right!

That design looks like it would work out and save on space. I'd try leaving the overflow tube out at first and only add it if you absolutely need it . If you size your doubler large enough, I'm sure you won't need it.

As far as what goes into a doubler at the start, I've tried water, mash, and low wines. Water gives lower abv, and smoothest/least flavor. Mash gives most flavor with a higher abv than water. Low wines gives highest abv and flavor between what water and mash will give. Right now I'm liking low wines as my favorite. It's a matter of what you like though.