Bubble plate loading

[KayDog]

Good afternoon guys.
I need a little help please on bubble plate loading with which I am struggling
I have a reflux still with the following parameter
100L thumper gas fired
100mm diameter column
Column height is 1M
Number of bubble plates is 5 off
Each bubble plate has 5 uppers and 1 downer
Dephlegmator on top of the column

When the still is running happily the output is a nice 93% abv. But for the life of me I cannot get the second plate from the bottom to load properly. The plate nearest the thumber is loaded, the next up will not load, the remaining two up to the dephlegmator load perfectly. The liquid level is to just below the top of the bubble caps on the “happy” plates, but the second from bottom does not load properly, it just has a thin layer of liquid on the bottom of the plate.

I have checked if there is liquid leaking past the plate at the tri-clamp gasket but nothing works.
I have tried different parameters, like increasing energy input, playing the flow through the dephlegmator and nothing seems to get it right. So it seems that I am running on three plates only and not all four.
What do you think my problem is?

Thanks in anticipation.
Cheers
KayDog

[30xs]

How much is a thin layer? For there to be any reflux returning to the bottom plate it would have to leak past the second somehow. Does the downcomer for that plate hold liquid? If it doesn’t then you will get vapor bypassing through it with no action through the caps.

[Prairiepiss]

If you put it in 100% reflux does it still not fill?
By what you said I am assuming you have a modular system where you can take plate sections out? I would take the triclamp off above the plate in question. Pour water onto the plate in question and see if it holds water. Or if it is leaking by. If it’s leaking by you should be able to see where it’s leaking through. And fix the problem. It sounds like you have a leak at that plate. Is the downcomer holding liquid to create the vapor seal? Are the bubble caps sealed to the plate. Is the liquid up to the downcomer drain level.

And I think you are calling the boiler a thumper. If it’s gas heated and that’s where you put your still charge. And the column mounts on top of it. It’s the boiler. If you have a separate boiler feeding another tank that feeds the column. That would be a thumper.

[KayDog]

Hi gents,


Thanks 30xs - it forms a thin layer of about 2mm
Thanks Prairiepiss - I will check for a leak as you suggest, it is a modular system. If I put on full reflux the top two plates flood and the "dry" plate stays the same. Thanks for the inputs, and yep it is the boiler I'm referring to not a thumper...(oops).

[Prairiepiss]

IF I were a bettin man I would bet that plate has a leak in it somewhere. Just need to find it.

Now hot alcohol layden liquid will flow different then cold water. So just plain water may not show the leak. You might need to try it with some alcohol. If the water doesn’t show a leak.

But you could move that plate to another position. It might work better in one of the other 3 positions.

[KayDog]

Thanks Prairiepiss - Love the handle....
The alcohol test is a good point, thanks

[KayDog]

Hi Guys,
Been looking into this and found that the bubble plates fit loosely in each recess and are not sealed off by the Tri-clamp gasket, so any deformity allows the liquid to bypass.
Is this normal, surely the gasket should seal off the copper plate as well?

[Chauncey]

I use teflon tape w my teflon gaskets to keep plates from weeping

[KayDog]

Hi Gents,

I found that the bubble plate assemblies rest loosely in the column and is not at all secured or sealed off by the tr-clamp gasket. Is this normal, or should the plate extend to under the gasket to enure a tight seal? The plate is thin so any deformation results in the loose plate not seating properly and allowing liquid to bypass.
Cheers and thanks in advance.

[Chauncey]

I use teflon tape w my teflon gaskets to keep plates from weeping

Use the tape bro

[Yummyrum]

Use the tape .

[KayDog]

Thanks Chauncey and and Yummyrum.
Is this the plumbers PTFE thread tape which comes on a roll which you guys are referring to? Do you just give it a few wraps around the edge?
Sorry for what might seem to be dumbass questions......


Thanks for the responses guys....
Cheers

[Yummyrum]

Thats the stuff .... BTW .. no dumbass question .... probably we just shit at explaining

Teflon tape is definitely something all distillers should have a few reels of on hand .

Yes , pain in the arse to do but you wrap it around the circumference of the plate several times ( trying to keep it as centred on the tape as possible ) then squish it flat on both sides . You should end up with a nice soft Pad around the plate that will help seal a loose fitting plate .

Keep a look out for the wider PTFE tape ( usually comes in bigger reels) as it is easier to apply than the thinner stuff .

[KayDog]

Yummyrum, you are the man!!!!
Much obliged and thanks for the help.

Cheers and happy distilling!

[SwollenGoat23]

I had this same problem.
I wrapped the tape around the actual Teflon gasket, passing through the center of the gasket to wrap up the edges and get a tighter seal from the tri clamp. Because I also had a leak at the clamp flanges. This seemed to fix those leaks but still had loading issues with 2 of the 4 plates.
The only time #1 or #2 on the bottom would load was when one above would "unload" or go from being loaded to only a small amount in action on to of it.

[KayDog]

Hey SwollenGoat,thanks for the response man!
Yep, I get a similar thing happening. I have 4 plates as well. Top plate is never an issue because its always loaded from the dephlegmator, so much so that I have to watch flooding. The next plate down fills then empties in cycles, dumping in surges onto the plate below it. The next one below that is permanently dry, only very rarely will it get liquid on it. The one above the boiler is perfect and is always consistently at the same level. Luckily no leaks at the tri-clamps though. Going to give the PTFE tape a bash this weekend and let you guys know.

Cheers

[shadylane]

Here's the best way I found for sealing plates

DSCF0228.JPG (28.77 KiB) Viewed 2724 times

[KayDog]

Guys, I am flabbergasted at the change in my still.
I wrapped the edge of each plate as you suggested and the change was dramatic. Less energy used, cleaner run with abv up to 93% from an original 88 to 92% fluctuation during previous runs. I had to keep adjusting dephlag and heat during previous runs to get the abv to stay above 91%. Now it stays at 93% steady and the hydrometer no longer moves up and down (bounces) in the parrot, just floats steady! And it held at 93% for the whole 4 hour run. I could also go deeper into the tails, as the I improved the output from 4.5L to 5.2 L, with a clean taste! I had to re-learn how to run the baby so much was the difference!
Initially the plates were flooded at the original gas setting, and I had to reduce heat considerably to get all plates to load properly. So I used less energy (gas) to achieve the same output. Thanks again guys, you are a bunch of boffins!