Building a bubble ball

[Anthoney]

After a lot of umming and ahhing I have made a small start. I cut the bottom off a stainless fire extinguisher and the top off a copper vase/jug. used a stainless dish for a plate and began the makings of a bubbleball. This is going to stand under a short 2" packed column of SPP with a 4" head for the reflux coil which will be movable to manage vapour without a valve as pioneered by Manu and Dad300. Hence the placing of a plate thread in the reflux section. The idea is to provide a reservoir of high ABV to feed the column with. This helps run with more power before the SPP floods at the top and keeps the ABV take-off constant at the end of the run by preventing the drying out of the bottom of the packing as the boiler temp rises in the depleted wash. The 4" head may also help with flooding, time will tell.

The pics should tell you better. Comments welcome. Nothing is soldered yet and the plate is not drilled for the caps either. So now is the time to tell me if I am doing something wrong. Only four caps are shown in the pic but I intend seven plus the downcomer. My local Screwfix ran out of 28mm caps. up and down comers will be 22mm.

The whole thing is seven inches in dia and about eight inches high. outlet is 2" inlet will be a bit smaller as I will use the screw in spear fitting from the keg.

I beat the copper out from concaveish to convex. Used the bottom collar and bottom bowl of the fire extinguisher. Pulled a dimple in the side of the collar for the site glass fitting. Used inch and a half as that is what I had that looked to fit well. Used an RJT hygiene fitting for the outlet. Again just what I had lying around.

Any questions on how anything was done I will be happy to answer but don't want to bore you with a blow by blow. A picture paints a thousand words and the sequence should be self explanatory.

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[Anthoney]

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[Anthoney]

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There will be seven 22mm upcomers with 28mm caps and one 22mm downcomer. The four caps are just for an indication of what it will be like.

[Anthoney]

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[Anthoney]

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Pulling the two inch dimple in the bottom of the bowl was MUCH harder than pulling the 1.5 inch in the collar.

[Anthoney]

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[Anthoney]

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[Anthoney]

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[Anthoney]

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[Anthoney]

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[Anthoney]

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[Anthoney]

I have seen people ask about using gauze instead of slots on bubble caps. They were always blanked with no reply at all that I have found. I take this to mean the answer was unknown to the people being asked. So I tried a little experiment using some 30 mesh stainless gauze scraps I had.

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Could see the air displacing the white spirit down the inside of the gauze. Bubbles came out from the gauze but only really at the top just underneath the edge of the bubble cap. Also mostly from the edge that was slanted highest. Seems to work though. 30 mesh might not be the best size to use. Something a little more open perhaps. Is what I have though. Main reason for using it is just to raise the caps a little higher to run with a deeper pool to bubble through.If it only comes from the top with ethanol as well then maybe there is no point as not getting more liquid vapour interaction from the bottom to the top of the pool. Will ponder some more before committing to an upcomer design.

Also brazed the inlet pipe from the keg into the bottom of the ball. No problem at this stage. Just more of the same.

After leaving the prototype in the jar with water I went back to it days later to show my nephew what I had been doing. When I puffed with the rubber ball on the end of the tube a cloud of tiny bubbles erupted from all around the skirt. Blowing hard produced a combination of big bubbles and tiny ones. It seems having time to become properly wetted has changed something. Some kind of surface tension effect I assume. The exact performance is obviously pressure dependant so I need to measure the pressure that is producing the cloud of bubbles and calculate the pressure in each of the seven upcomers to compare the two and have some prediction of how the 30 mesh skirt will behave in practice. I was just about to buy a small amount of 20 mesh to try but, if the pressures match, the 30 mesh is fantastic once wetted.

My friend has built and programmed a more modern version of the Russian electronic pressure sensor and added control capabilities so that it can turn off the heater if the pressure gets too high in the column. An anti flood/puke measure.

He lives in another town but he has finished it now so I need to get it from him as a use for it has become evident and imminent. Scared to have it posted as royal mail has just lost the last parcel I was expecting. Bit dear to drive up there to get it but I might have to do that or take a deep breath and risk the post again.

[MacStill]

Hmmmmmm :think:

Thought, pics, tutorial, effort, detail, creativity......

Hmmmmmmm :think:

Fuckin 10 out of 10

I love it :handgestures-thumbupleft:

[emptyglass]

Hi Anthoney, well done. Big effort on both the ball and the post.
You did exeptionaly well, or were exeptionaly lucky to find a fire extinguisher and vase that matched. Again, well done!

I'm a bit of a bubbler fan, so my first question is have you considered a plain old bit of plate with holes?

Thinking about your mesh, did you make sure you bled allthe fluid out on your first try? I only ask, because if you didn't, that would provide an opening behind the mesh for the air to head straight to the top. And I'm thinking that a few days later it would have bled out by itself. But you are probably right, it 's just a wetting thing.
I would like to give mesh plates a go, but like you, I can't find difinative answers. No one I know seems to have tried that one.

[Anthoney]

Thanks McStill. Praise from you is very rewarding.

EG, the cap was submerged in a jam jar. It was full of fluid. It was still full of fluid later on. It was not a complete bubble cap assembly. Just a test of principle with a bit of mesh around the cap and air piped in underneath. I could see the air pushing the fluid down towards the bottom of the mesh but only coming out near the top. I expect having vapour instead of plain old air would make a difference but I hope a better one. Likewise with ethanol instead of white spirit or water as the liquid.

The jug was a bit bigger than the fire extinguisher, hence those tabs. I could have cut them down even further and still had enough strength in the joints. Braze is much stronger than soft solder and only needs a short joint. Half again would probably have been fine but I just did what was easiest with the snips.

A perforated plate is easier to make I know. I also know they do work if you size the holes right and use the right number of them. The potential problem with mesh is not just getting the hole size right but the ratio between hole and surface. Mesh of a given hole size is made with a particular size of wire and I know of no choice in the matter. So while I might like a mesh made with a thicker wire and a smaller hole than usual that option is not available that I know of. It may not matter, I really don't know. It's a new area to me and I can't find information from anyone who has tried it.

Bubble caps are less inclined to dry up towards the end of the run and so provide a more constant output for longer as they carry on doing the job to the end even as the wash depletes and vapour temps rise. For this reason I prefer them to perforated plates in this application.

Rather than wait to get my pressure meter I may just make it and see. But if I do that I need to try and flange that last joint so I can open the ball up again easily. Considering Cleco side clamps to hold two home made flanges together. Flanges would be a bit thin as made from old stainless trays. So bolting through might not be best. Although spring loaded the Cleco clamps are a far cry from bulldog clamps sometimes used to hold lids on. They exert 70lb/31.75kg of force per clamp and are used in aviation construction for holding skins in place before riveting. I was thinking ten clamps evenly spaced around the ball, each exerting the same even pressure. Despite the combined clamping force I am a little concerned as I don't know what the leverage forces on even a short column full of SPP might be. My gut says yes and my head says probably. I could try and calculate them but I am a bit lazy unless I am enjoying the work. I'll try to make the flanges first and see how they feel.

The problem with the bubble caps and the thin stainless bowl I am using for the tray is how to ensure they are all just the same hight. The tray is warped from drilling and possibly too much heat and so it is a problem. I could find a thicker plate and just measure the length of each upcomer carefully and may do that but I think I have thought of a way to keep the caps at the same hight despite the uneven tray. Time will tell if I am right. I should have my TIG working in a week or so and that may help but not what I am counting on as the tray is already uneven. Yes I know I am teasing a little but I am interested to see if my solution is a common fix people are going to chime in with or if I have actually thought of it first. I doubt it, it's a simple one, and it doesn't really matter as the joy of discover for oneself is the same regardless of how many others have enjoyed the same discovery. Well nearly the same lol. The only clue I will give is it interacts with the other problem of making sure the plate is level in the ball. If no one tries to guess then you will have to wait until I have tried it to find out what it was and if it worked.

[emptyglass]

I don't care what way you go mate, with what you have done so far, I'm sure you'll pull off what you plan.
I await your results with baited breath.
But I hope your new tig has plulse, upslope and downslope, or if your ass points to the ground you will warp it. Good electronic sheild would be on the list too.
I hope your secret wepon is not a spirit level, or I will be most dissapointed.
If it was me, I'd set the keg level to the world, attach the ball with gasket, and set the cap heights with a level and rule.
Otherwise, I'd think outside of the english box, and go perf, but thats just me.

Sorry mate, just tring to get the answer out of you, with a bit of tesing.

And dude, I tip my hat to you if you managed to braze stainless without a mess. Beyond my abilitys. Seriously. Good work mate.

Cleco clips would be a second option for me. And you need pliers (pm if you need plans to make your own). They are costly and are meant for manufactuing, not the end job. I'm guessing you mean the pinch clamps, not the rivet hole ones. go triclamp.

[Anthoney]

Thanks for the vote of confidence. Well there is a spirit level involved at some stage but it's more about how to have unequal length risers that exactly compensate for the uneven bowl. It really is easy if it works.

The tig is a big old three phase 500A ac/dc water cooled type with slope control and a knob that claims to be able to vary the temp of the weld pool that I assume is some kind of pulse control. The same mate who built me the pressure sensor is on a promise to build me a separate pulse control box that can be plugged in to the control socket on the front. My electronic shield is not up to tig. It is a good brand but only mig friendly. I have the nod it down type for now. When I had three phase before it was the thin stuff I found the most difficult not to burn through let alone warp. Still learning as only had a mig before. Flow meter for the argon helped a lot as I remember. My memory is generally deteriorating as I get older so I have to relearn things I used to know how to do. Goes quicker on the reruns though. Then I'm ok unless I stop for any length of time.

Making a neat braze on stainless is easy... Just grind the mess off later lol. The flux does tend to stray and then the silver follows. I err on the side of too much flux at the moment. I may cut down as I get back in the swing of it. Grinding the surface down with the Dremel just before brazing helps a lot.

Yes I mean the, don't get your finger in them, pinch clamps. They are not too dear from ebay; cheaper than a 7" triclamp and two 7" SS ferrules I think. Despite having a collection of tools and materials built up over time I am not rich and cost counts.I know they are for manufacturing really but they seem up to the job. You wouldn't want to fly a finished plane on them but for a still they may do even long term. I really don't want to braze it shut if I can help it.

[Anthoney]

Perhaps this will help.

"Most brazing of copper is done using fittings that are designed for soldering. As a result, the socket depth is about two-thirds of the diameter of the tube. You need that overlap when using solder, but when you braze, all you need is for the tube to be inserted two times the thickness of the tube to develop a joint that is as strong as the tube itself."

Google Brazing Dimpler and you will find a host of reference to the shorter joint needed because of the high strength of braze. Some of it from the people selling a tool to help achieve this cost and time saving but much also from independent sources verifying that this is indeed true and not just a marketing ploy.