Preliminary design phase, question about bubbler length:

Perforated & bubble cap plated columns

Preliminary design phase, question about bubbler length:

Postby GaffaJack » Thu Jul 23, 2020 1:17 pm

Hi Guys,

Just planning my first bubbler build, planning to make a 4" bubble column, running on gas with a good quality high output burner, 50-70l wash pot.

Have looked around in the forum and haven't found a simple answer to the following question: Is there a minimum gap required between plates or am I limited only by the depth of liquid I want to bubble through?

Say I have a 200mm long column with four plates in it, that gives me about 40mm between plates, and if the down tubes start at 10mm above each plate, that gives a vapour gap of about 30mm. Will the plates still load? trying to keep the height as short as possible so that I have plenty of room for a carter head..

Cheers,

Gaffa.
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equipment: Still building, but so far:
handmade (macguyvered) 5 litre reflux, cooktop style, soon to be 20L..

Re: Preliminary design phase, question about bubbler length:

Postby tubbsy » Thu Jul 23, 2020 1:33 pm

the rule of thumb is plate gap is at least the diameter of the column, so you'll want your plates at least 100mm apart. Any less and you'll be splashing the underside of the plate above and cause smearing.
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equipment: 10L stock pot with 1.5" boka and a 50L Keg with a 3" Boka on a 1500mm column.

Re: Preliminary design phase, question about bubbler length:

Postby GaffaJack » Thu Jul 23, 2020 1:48 pm

Thanks for the prompt reply, Tubbsy, I figured there would be a reason.

I'll double the length of the column, plus a bit.

Cheers,

Gaffa
GaffaJack
 
Posts: 8
Joined: Thu Jun 04, 2020 12:05 pm
Location: Southern SA
equipment: Still building, but so far:
handmade (macguyvered) 5 litre reflux, cooktop style, soon to be 20L..

Re: Preliminary design phase, question about bubbler length:

Postby RC Al » Thu Jul 23, 2020 2:06 pm

I wouldn't go under diameter on a 4" and would recommend much taller, 6-8 inches

Heres a link to a running bubbler vid https://www.youtube.com/watch?v=Qe9whVpbt60&t

That particular still isnt loading the top and bottom plate very well so concentrate on the 2 middle ones. Note that the bubbles are far higher than the downcommer height (20mm?). The plate needs that head space for the bubbles to explode and help separate the components. Lowering the roof will cause the exploding bubbles to go straight up the above risers and cause whats called entrainment, leading to the smearing mentioned and a loss of efficiency. To counter that you would have to run at a lower power input and you may have well built a smaller still.

The carter head dosent have to be at the top of the still, it can be positioned wherever your condenser will allow you to place it with some extension spools, many feet away if you wish
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Re: Preliminary design phase, question about bubbler length:

Postby GaffaJack » Thu Jul 23, 2020 2:41 pm

Thanks RC, point taken. looks like I don't fully understand the carter head either. I'll do more research.

I was under the impression it was a good idea to keep the vapour train as short as possible, in order to keep the carter head running hot when infusing gin. Most of the examples I've seen seem to run the carter head slightly offset but mostly above the bubble/reflux column.

Google here I come!
GaffaJack
 
Posts: 8
Joined: Thu Jun 04, 2020 12:05 pm
Location: Southern SA
equipment: Still building, but so far:
handmade (macguyvered) 5 litre reflux, cooktop style, soon to be 20L..

Re: Preliminary design phase, question about bubbler length:

Postby RC Al » Thu Jul 23, 2020 3:08 pm

Some insulation on the pipes will cover any losses if desired, not many bother
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