External-wrap dephegmator?

[ruminant]

I've been reconstructing the still head on my pot from the hideous funnel-and-mixing-bowl contraption I came up with before discovering these forums into a tri-clamp set-up with a chamber for my copper Raschig rings and other goodies. Rebuilding gives me an opportunity to tinker, so I wanted to get some advice on this idea (to be used for rums and whiskies).

Has anyone worked with an external-coil dephlegmator? I'm talking about wrapping 1/4" copper tubing around the outside of a tri-clamp spool, to be attached at the top of the still head. Would I be able to add a bit of reflux to my pot without going full column? Should I choose a 3" pipe or a 1.5" pipe for the inner spool? Copper or stainless?

(Ozark Still Works sells one they call The Shocker, which looks cheaper and prettier than anything I could build, but why spoil the fun? https://ozarkstillworks.com/product/?the-shocker-)

[still_stirrin]

Can you put packing in the riser turned column?

The coil over the vapor pipe solution is not very efficient at knocking down much vapor, but will cool the pipe enough to create some condensation on the inside wall of the pipe. Packing would allow interaction of the falling (cooled) condensate with the hot rising vapors thereby increasing the heat transfer between vapors and condensate. That would help the reflux and help improve separation.

External coils being so inefficient can be improved upon by the classic cross tube coolant pipes. But even those are not really effective. The traditional dephlegmator/shotgun-style condenser (multiple vapor tubes inside a water jacket) is much better for this type of reflux condenser duty. But of course, it is more challenging to build than wrapping your riser with 1/4” ID soft copper tubing.

In the end, it is the packing which actually helps the heat exchange between vapors and condensate and that is required for reflux.
ss

[greggn]

so I wanted to get some advice on this idea (to be used for rums and whiskies).

If you're *not* going to be making vodka, and only want a little passive reflux, then you'd save a lot of money by just adding a spool to your existing riser and pointing a small fan to blow air across it.

... but, as SS said, there's not much value in reflux that doesn't have a medium to facilitate heat exchange. Somewhere here are discussions about commercial distilleries and their use of angled lyne arms to influence product. I believe the consensus is that it has no real effect at the hobby level.

[Saltbush Bill]

A dephlegmator doesn't only provide reflux. To do it's job properly it needs to be more than a few coils wrapped around the out side of a column. It's other job is to only allow the more volatile components of the wash / vapour to leave the still at a speed and purity of the still operators choosing.
Quote
"Vapor leaving the device has become concentrated in the more volatile components, while the condensate is richer in the less volatile components."
https://www.thermopedia.com/content/691 ... %20gravity.

[ruminant]

Thank you all for all of the advice. At this point, I'm just going to plan a few experiments with minimal cost, using a six-inch SS conical reducer I already own with a filter plate under it so I can try it out with/without packing and with/without cooling from the external coil. (I'll also be doing more research, though I don't think it'll dissuade me from playing with copper.)

My expectations are pretty low, but I'll report back here with the results in a year or so.

[Demy]

I believe that such a system does not allow you to make many adjustments ... an internal coil instead can be adjusted by water flow, i.e. you can go from very to little reflux gradually .... this allows you an adjustment that affects the finished product. An external coil does not allow much adjustment and is certainly not very efficient.

[acfixer69]

Since energy travels from hot to cold the condensed liquid would channel down the column walls back to the boiler and have minimal interaction with packing. Waste of energy.

[Steve Broady]

This got me thinking.. since copper is a pretty good conductor of heat, would internal fins help to make such a condenser more efficient and controllable? The only real advantage I see is that it makes the construction a little simpler since the water and vapor paths don’t have to cross each other. That, and it might look kind of neat, if that matters to you.

[ruminant]

Demy, I agree with you on the inefficiency of external coiling--especially around a SS spool--but I'm not sure how control would be any different, since you'd still be able to modify the coolant rate. Can you elaborate?

acfixer69 you make a really good point, and I nearly abandoned the experiment as soon as I read your comment. But how is that different from the kind of passive reflux you get from a Scotch goose-neck? I'd think that those also have condensate running down the column walls while vapor passes up the center, right? (Now I'm getting delusions of grandeur by inventing goose-necked techniques at a hobbyist scale -- anybody else ever get carried away like that?)

Steve, I do think you're right, and had thought about soldering some of my 1/4" copper Raschig rings to the interior of a copper spool for that purpose. As long as I'm cheaping out by using stainless for my spool, I feel like the conductivity may be so poor that extra surface area of the interior spool might not matter very much.

[Twisted Brick]

The external-wrapped dephlegmator design has appeared and died previously. Generally, unless brand new, if an idea is legit, (practical, effective, affordable) it will have been adopted and endorsed across a broad number of members (ie CCVM). Same applies with retailers.

[ruminant]

Okay, you've convinced me. It looks like building a cold finger would be a more effective way to scratch my fabrication itch -- I can even use a spare 1.5" tri-clamp tee I've got sitting around.

[shadylane]

Okay, you've convinced me. It looks like building a cold finger would be a more effective way to scratch my fabrication itch -- I can even use a spare 1.5" tri-clamp tee I've got sitting around.

A suggestion.
If the coil was on the inside, it would be a dimroth type dephleg and work much better.

[Saltbush Bill]

The external-wrapped dephlegmator design has appeared and died previously. Generally, unless brand new, if an idea is legit, (practical, effective, affordable) it will have been adopted and endorsed across a broad number of members (ie CCVM). Same applies with retailers.

Its pretty hard to re-invent the wheel around here , there isn't much that hasn't already been thought of and tested by at least a few folk.
If it works it works, if it doesnt it sinks to the bottom of the pile.
There was a post here somewhere recently and a link to a fellas site where someone was trying to sell this type of condenser.

[Wildcats]

1/4* copper tubing. Filled with salt and wind the coil. A lot of help here on winding you're own. Or buy one already made.

[Chauncey]

OP: I have used one of these setups in 1.5"
They work better than expected. I used it to make whiskeys in 1 and done runs using the 1.5 run protocol.

A dephlegmator doesn't only provide reflux. To do it's job properly it needs to be more than a few coils wrapped around the out side of a column. It's other job is to only allow the more volatile components of the wash / vapour to leave the still at a speed and purity of the still operators choosing.
Quote
"Vapor leaving the device has become concentrated in the more volatile components, while the condensate is richer in the less volatile components."
https://www.thermopedia.com/content/691 ... %20gravity.

That says to me that CM stills actually make a different product than other types of reflux stills. Food for thought.

[NormandieStill]

I always figured that if you could perfectly control the coolant temperature (not temp out, but temp in) then you could in theory selectively condense certain molecules allowing you to trap higher BP molecules. Not sure that this is technically possible mind. Does the condensing point of a vapour mix behave like the BP of a liquid mix?

[googe]

Would add some reflux, might get 70% or so, hardly worth it for the cost. Could build an entire still for $170.

[Chauncey]

Yea in the end it's better to just do it right. Def attach the coil if you're going external