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How to put multiple plates in the one pipe

Posted: Sun Apr 14, 2019 9:25 pm
by smithy540
Hello everyone,

i'm interested in the manufacturing method people use to seal multiple bubble cap plates or sieve trays into the one piece of pipe. For instance how the Chinese still manufacturers put 4+ bubble caps in one pipe. Is it with a plate tree? If so, how is each plate sealed to the column wall without the use of gaskets?

If they aren't sealed, surely vapours will just shoot up around the outside?

Or do they solder each plate in by hand with great difficulty?

Cheers

Smithy

Re: How to put multiple plates in the one pipe

Posted: Sun Apr 14, 2019 10:14 pm
by MichiganCornhusker
All of you answers can be found here:
viewtopic.php?f=17&t=59216

Re: How to put multiple plates in the one pipe

Posted: Sun Apr 14, 2019 11:21 pm
by Saltbush Bill
There is more than one way to skin that cat and plenty of build threads on the different forums that give good examples of how and why.

Re: How to put multiple plates in the one pipe

Posted: Mon Apr 15, 2019 6:37 am
by emptyglass
There is many more than one Chinese still makers out there. They all have their own approach. Would have to have seal details to have a say on how good their approach is.

I'f you are using a plate tree system it can be done and in the right hands can be made to seal well enough. Gasket type systems are more reliable.

soldered plates in a solid body plated column are possibly the theoretical best approach. also the cheapest. but can be a headache if you dont get it right first time.

Re: How to put multiple plates in the one pipe

Posted: Mon Apr 15, 2019 6:44 am
by HDNB
the part of this, that seems obvious to me is that vapours are supposed to go by the plate. so snug, yeah...sealed? why? as long as the gap is small enough that the liquid does not fall back readily while under the influence of rising vapour, seems to me you would be fine. of course, i'm no pro still builder so empty's words are not, you know, empty.

Re: How to put multiple plates in the one pipe

Posted: Mon Apr 15, 2019 7:09 am
by Bushman
HDNB wrote:the part of this, that seems obvious to me is that vapours are supposed to go by the plate. so snug, yeah...sealed? why? as long as the gap is small enough that the liquid does not fall back readily while under the influence of rising vapour, seems to me you would be fine. of course, i'm no pro still builder so empty's words are not, you know, empty.
I do not have a plated column but my dephlagmater drops in from the top and I purposely left a slight gap around the outside. This serves as a 6th vapor path on my CM. When I am throwing more coolant during the equilibrium stage no vapor escapes through the outside gap.

Note: Not directly related but ties in with what HDNB is saying.

Re: How to put multiple plates in the one pipe

Posted: Mon Apr 15, 2019 9:33 am
by Setsumi
On a plated column the issue is not vapours that pass the plate between the column wall and plate, it is rather the liquid that dumps there. If the plate holds liquid any leak on the wall will boil. If the liquid dumps the plate does not work but with a reasonable fit it works, some need bit more power but look at perforated plates...

An issue I have found is that a central hangee/rod can mess with the column wall plate fit due to torque, my solution was to put only 2 plates on a rod that is tightent by nuts.

Re: How to put multiple plates in the one pipe

Posted: Mon Apr 15, 2019 10:11 am
by Setsumi
Maybe a photo will explain. My bottom plate sits on feet. The following 2 are fixed on a ss rod with nuts and the rod space on the bottom plate but the rod is not fixed on the bottom plate with nuts as it creates torque an messes the column wall fit. The bottom plate is a bit to loose, fixed with some teflon tape.
Then I have my 4th plate on n ring in my copper section with the top plate spacing again on a central rod but not fixed to the 4th plate.

The photos are in the wrong sequence.

Re: How to put multiple plates in the one pipe

Posted: Mon Apr 15, 2019 12:49 pm
by LWTCS
HDNB wrote:the part of this, that seems obvious to me is that vapours are supposed to go by the plate. so snug, yeah...sealed? why? as long as the gap is small enough that the liquid does not fall back readily while under the influence of rising vapour, seems to me you would be fine. of course, i'm no pro still builder so empty's words are not, you know, empty.

A bit of smearing if the plate weeps. But likely won't under the pressure of the kettle heat produced.
A small loss in phase change efficiency.
Both bad behaviors may contribute to smearing, quality of separation, and collection speed.
Is it really a bad thing? Depends I guess?

Re: How to put multiple plates in the one pipe

Posted: Tue Apr 16, 2019 3:53 am
by emptyglass
Its a case of control, or lack of it.

If the plates dont seal, how do you know how much each plate is leaking?

One plate may leak more than another, so you loose balance and have plate activity thats not correct for its position in the column.

Assuming each plate leaks the same amount the still may appear to function fine. But what LWTCS said comes into play. In this situation it will be a struggle to get above 92%.

When all the plates seal, the still runs better with less issues.

Re: How to put multiple plates in the one pipe

Posted: Tue Apr 16, 2019 9:57 am
by LWTCS
Good point Empty.

Re: How to put multiple plates in the one pipe

Posted: Tue Apr 16, 2019 11:56 am
by googe
I soldered three plates in a column once, total nightmare stress city with downcomers, caps desoldering!. But worked great when I got it done finally. If you want to solder plates in, I'd look at screw mountable downcomers, caps etc . In my experience the tinniest hole plays havoc with how a plater runs.

Re: How to put multiple plates in the one pipe

Posted: Tue Apr 16, 2019 12:07 pm
by Saltbush Bill
Why not hard solder cups and downcommers Gooman.....then soft solder the plate in?

Re: How to put multiple plates in the one pipe

Posted: Tue Apr 16, 2019 9:23 pm
by Yummyrum
Saltbush Bill wrote:Why not hard solder cups and downcommers Gooman.....then soft solder the plate in?
Good method there Salty .

On one of the early builds I read , the guy used 4” lengths of spaghetti and used them as spacers to hold the plate in place while he soldered it . Another few lengths and in goes the next plate etc . Then at the end he removed them via the sight glass holes .

IIRC Olddog had issues with his bottom plate not holding liquid . Remember that in those days the plates were simply cut out with tin snips and finished off with a file . Eventually olddog realised it was the gap around the plates that was causing the issue and strangely it seemed to only effect the bottom plate .

Soon guys started spinning the set of plates in a drill press against a file or grinder so get them closer to perfect . This made the gap so close that loading issues didn’t seem to be a problem anymore .

Its all there in Flute talk thread and olddogs initial flute build threads .
Also of interest is Emptyglasses Flute build where he also made a solid pipe type but found that due to brazing on his sight glasses , his pipe had become out of round .
He fixed this by ramming a swagging tool down it to straighten it up so his plate tree would slide in more true .

There’s some real gold in those early build threads :thumbup:

Re: How to put multiple plates in the one pipe

Posted: Wed Apr 17, 2019 10:12 am
by Setsumi
Yummyrum wrote: IIRC Olddog had issues with his bottom plate not holding liquid . Remember that in those days the plates were simply cut out with tin snips and finished off with a file . Eventually olddog realised it was the gap around the plates that was causing the issue and strangely it seemed to only effect the bottom plate .

Soon guys started spinning the set of plates in a drill press against a file or grinder so get them closer to perfect . This made the gap so close that loading issues didn’t seem to be a problem anymore .

Its all there in Flute talk thread and olddogs initial flute build threads .

There’s some real gold in those early build threads :thumbup:
If I recall correct the issue with the bottom plate of olddogs first build was actually too small downcommers, BUT I have been wrong.

Having a consistent heat input is for me a bigger isue than a bit of weeping. If your heat input is constant and enough to keep your plates loaded just above dumping you should not have weeping, if you get weeping your fit is very bad or your heat is not enough to have proper vapour speed to keep the plates loaded. I run on propane and a small disturbance in the flame can dump my plates.

Re: How to put multiple plates in the one pipe

Posted: Wed Apr 17, 2019 9:58 pm
by smithy540
Thanks for all the replies everyone! Since i'm building quite a large diameter column, i'm going to cut each section shorter than I was going to and try to weld each plate in place and use screw in bubble caps, attach via sight glass holes. Time to buy a really short electrode holder for my tig torch.

Re: How to put multiple plates in the one pipe

Posted: Wed Apr 17, 2019 10:14 pm
by smithy540
This one is welded, but not all the way and has a lip on the plate. Interesting.

Re: How to put multiple plates in the one pipe

Posted: Mon Apr 22, 2019 6:42 am
by emptyglass
Thats a tack to keep it in place. The lip is a weir.


@yummy, thats why I've stuck with soft solder for sight glasses. Those early days of brazing them on caused more problems than it ever helped with.