Sight glass placement in a SPP-packed reflux column

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carbohydratesn
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Sight glass placement in a SPP-packed reflux column

Post by carbohydratesn »

Hi all. I've been thinking about this a lot lately, and could use some input. Some searches haven't turned anything specifically on this topic, so - it's question time! And it's a lot of questions, so feel free to duck out now, skim, whatever. Any input is appreciated.

I've been very happy with my reflux column so far, SPP is a joy to run. But I'd like to make it a little more user-friendly. A glass column would be fun, being able to see the progression of fluid up the column is powerful. Copper is what I have, though, and it's all I'm going to have for a while. So - sight glasses are in order!

For cost, I think I'm going to have to go with 1.5'' trap adapters and 1.75'' diameter 3/16'' thick borosilicate disks, as discussed here and mentioned here. 2.25'' disks fit in the 2'' trap adapter, so I'm assuming the same 1/4'' difference applies for the smaller adapter/glass.

It seems like a no-brainer to install two of these in the column directly above the packing. From what I've read, this is the most beneficial part of the column to be able to see clearly.

That part of the column is open, so light can bounce around. Should I install those glasses opposite each other? I have a feeling that would mostly let me see *through* the column, which wouldn't be very helpful. A little thinking says they should be installed at a right angle to each other, or less, so light can enter one glass, bounce off the inside of the column, and everything will be visible from the other glass. Does this sound like a solid idea?

Would it be helpful at all to install any glasses lower down the column, in the packed section? I'm mostly thinking about the 'zones' Odin wrote about in this post. This is where I could use the most help!
Odin wrote:To sumarize it: an SPP filled column has different zones, when working optimally. That's based on above explanation as well as of careful observations of both my glass SPP rig and my bigger rashig ring packed rig. From the bottom to the top:
1. Aquatic environment (aka semi-flooded, where I use semi to say you should not actualy flood the column);
2. Semi-aquatic environment (notice that I use the term aquatic to state there is liquid, not stating it is water, it can be high abv reflux as well);
3. Non-aquatic environment (roughly the middle of the column);
4. Another sem-aquatic environment;
5. And the aquatic environment at the top.
Is there any benefit to trying to keep tabs on and maintain zones like this? Should the middle of the packing really be 'dry'? Or is keeping the entire packed section fluidized a better goal?

As long as my reflux is not overly cooled, and there is a scrubber above the SPP to allow the reflux to penetrate better and plenty of empty space above that, can I just assume that an aquatic environment at the top of the column means the column is in its optimal state? Or would an eye on different sections of the packing give me a better idea of how exactly the column is doing?

Sight glasses like this sticking out of the packed section, with packing filling them and pushing out against the glass, could be a huge weakness. Should glasses like this only be used in 'empty' parts of the column? I do have one tri-clamp connection in the middle of my column - it feels like a round 2'' inline sight glass would probably be a much better idea here. If an eye on the middle of the packing would be useful, but flat glasses would be too risky, this is probably what I'll have to go with.

Is it okay to dress a packed column up in a flute costume? Or will this give too much of a false impression if I ever show it off? :lol:

Well, that was a lot of writing editing. I think I got everything out of my head and onto paper, though. There's been too much rattling around up there about this stuff for the past few days. So perhaps I'll fall asleep a little faster tonight :)

You're all wonderful people, and I'm glad to have such a great community for support in this hobby.

May your blended product always have exactly the right amounts of heads and tails,
-carbohydratesn
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Re: Sight glass placement in a SPP-packed reflux column

Post by Bushman »

Flutes do have the cool factor, as far as putting site glasses in a packed column as opposed to a plated column, I would not think they offer a lot of additional information. With a plate it is nice to be able to see if your flooding the plates or if all the plates are performing properly. With a packed column I guess you could see a little and it might tell if you are experiencing entrainment but other than that I am not sure you are gaining much.
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Re: Sight glass placement in a SPP-packed reflux column

Post by DAD300 »

At the top, between SPP and takeoff, it would tell you if you have the top flooding out of control.
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Re: Sight glass placement in a SPP-packed reflux column

Post by skow69 »

carbohydratesn wrote:
Odin wrote:To sumarize it: an SPP filled column has different zones, when working optimally. That's based on above explanation as well as of careful observations of both my glass SPP rig and my bigger rashig ring packed rig. From the bottom to the top:
1. Aquatic environment (aka semi-flooded, where I use semi to say you should not actualy flood the column);
2. Semi-aquatic environment (notice that I use the term aquatic to state there is liquid, not stating it is water, it can be high abv reflux as well);
3. Non-aquatic environment (roughly the middle of the column);
4. Another sem-aquatic environment;
5. And the aquatic environment at the top.
Is there any benefit to trying to keep tabs on and maintain zones like this? Should the middle of the packing really be 'dry'? Or is keeping the entire packed section fluidized a better goal?
-carbohydratesn
I wish Odin would post photographs. The bottom zone is aquatic, which is not flooded, but semi-flooded. The next is semi-aquatic, so that must be somewhere between semi-flooded and not flooded. The top is aquatic. Does that refer to the top few inches of packing or the dancing geysers above the packing? I can get one without the other.

I consider Odin a great mentor. I have learned more from him than I can ever repay. But he can be a bit opaque at times.

I think I would put one on top, as high as possible while still seeing the top of the packing, and call it good. My opinion continues to change (as you know) and will until I find the right test, but at this point I think it's sufficient to run the rig by the geyser dance. Any information you get from the middle is more about the packing than operation.

Keep us updated with whatever you do.

Skol,
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Re: Sight glass placement in a SPP-packed reflux column

Post by carbohydratesn »

Great, that makes my job a lot easier then. Sounds like sight glasses down the column would be way more complicated than they're worth. I'll definitely keep y'all updated, and I might even post some pictures finally :) I have two big upgrades planned to overhaul the top of my column right now, and this is one of them. A few updates to the standard 2'' bok design that's so readily accessible in the reading lounge. I built my column based on that material, and further reading has lead me to want to make a few changes.

Basically - SPP packing instead of scrubbers or mesh, a stainless condenser and bok head instead of copper, and two simple and compact sight glasses to go along with the SPP. When they're all done I'm hoping to do 'roundup' post for the benefit of anyone planning to make a bok in the future, with links to the info that's influenced these choices. They're all straight upgrades to that design, making it simpler, easier to make, and more effective, or, at the absolute worst, one of them will make it slightly harder to make- the stainless bok head will be much harder to cut slots into. But that's optional, and even with a copper head, a CSST condenser is still a straight upgrade to even the best copper condenser.

Thanks for the input so far!
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Re: Sight glass placement in a SPP-packed reflux column

Post by Hound Dog »

I have a trap adapter sight glass at the top of my packing. I have a boka style head so I placed one across from the bottom plate too so I could see the reflux exact. The most useful is the top of the packing so I can see the flood rise to the top and back it down into the packing just a bit. Also so it does not get out of control and actually flood out the top. I think if you put it down in the column it would create a void and just fill with fluid. I don't think it would give you a true picture.

Placing two across from each other to look straight through might be a cool idea. I think Mash Rookie did this on a flute build. No real need to see the pipe behind what you are viewing. I just put one in and need to view with a flashlight. Kind of a pain but really I just look up to see the flood stage and back it down. The close up viewing novelty wore off.
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Re: Sight glass placement in a SPP-packed reflux column

Post by carbohydratesn »

They have arrived!

Some 1.5'' trap adapters from Supply House, and a few 1 3/4'' diameter, 3/16'' thick borosilicate glass discs from McMaster-Carr.


Image

Full size version of that image

It's a perfect fit :D I'm surprised by how clear the discs are, they're practically invisible. The lower brass piece has a disc in it - all you can see is the ground edge of the glass.

The trap adapters will definitely take some sanding. The inner surfaces and the edge that makes a seal with the glass are both very rough. I wasn't expecting a beveled edge for that, but I guess it makes sense, considering that they're compression fittings. They came with plastic compression rings - those are getting thrown out.

I think I'll install one on the column to start, to see if enough light gets in. If it's too dark, I'll put a second one up there to let some light in. Might even mount a flashlight to it somehow.

Otherwise, I think the second one will be going on my boiler. A lot of weird sounds come out of there, it would be nice to be able to see exactly what's going on.

Thanks for the help so far everyone! I'm excited for this upgrade.
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Re: Sight glass placement in a SPP-packed reflux column

Post by Odin »

Hmmm ... this makes me thinking ...

Not sure this is the best approach. I will explain why.

If I understand correctly, you have a column. Same diameter bottom to top. Now we introduce sight glasses. Not a glass section of the same diameter, but a sorta T-section, where on the horizontal ends you put the glasses. As if it were a Flute.

If I do not understand you correctly, and the above interpretation is incorrect, sorry, my apologies.

But if I do interpret correctly, this is what will happen:
1. Pressure differences;
2. Vapour channeling;
3. No action where you actually want to see it.

The glasses make the column wider. This creates a zone of relatively lower (micro) pressure. Also, reflux decending from the top all of a sudden has to spread out over more surface area. Hence vapour channeling.

Now, the most interesting parts of the refluxing action is where the so-called water baths develop. Top and bottom of the column. Now, for sure, these are exactly the places where you (1) want to peak in, but (2) by creating a different diameter you will not allow these liquid baths to develop.

The only way in which you can do this is by:
1. Putting in a complete glass section/tube, same diameter as the rest, at top and bottom ... and then you can "flood" them;
2. Making holes in the column and glueing the glasses in, in such a way that throughput and column diameter are not changed.

Regards, Odin.
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Re: Sight glass placement in a SPP-packed reflux column

Post by carbohydratesn »

I wondered if putting some mid-column could be a good idea - and it isn't. It's obvious that it would cause some problems, but I wondered if the extra view into the column would be worth it. The responses I got cleared that right up - it would have been a bad idea, like I thought it probably would be.

I'm going to be putting the sight glass above the packing. There's already a lower-pressure area here, like in every reflux column - open column instead of packed. The bottom of the sight glass will be at least an inch or two above the top of the packing, reflux should never enter it under normal operation.

I'm going to make the glass as low-profile as possible, maybe even removing the whole smooth part of the trap adapter to give it the lowest profile I can. Ideally the brass part would screw right down until it's almost touching the column.

Will a small protrusion like this really impact the performance of the column?
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Re: Sight glass placement in a SPP-packed reflux column

Post by Odin »

Good thinking. And so sorry to spoil the fun.

In all honesty ... even at full power, the "fun" of looking at an all glass column pakced with SPP is not so great as for instance looking into a Flute. Well, apart from tech & innovation & theory addepts like myself. And putting a sight glass half way ... that's where not much seeable happens at all. Above the packing is a good idea, even though I feel (yet, I am not able to explain with theoretical foundation ... yet ...) that a column cooler close to the packing is better.

Okay a start ... to all, not to the OP in special ... everyone thinks that when gasses cool to liquid state, especially in a azeo column like LM or VM ... that temps of gasses and reflux are (almost) the same. I can tell you they are not. The act of switching from gass to liquid state draws so much energy that the temperature of that reflux is closer to 68 degrees than to 78 degrees C.

Okay, can't help myself. Did I mention the surface area maximalization theory is out of the window here? And that I want to replace it with what I call the "Bullit in the Fishtank" explanation? Now understand that the bullit is the rising gas molecule and it hits water or reflux ... that actually cools it while traveling upwards. Do you start to get a feeling of the miraculous workings of SPP?

I know I do!

And the funny thing is you don't even need SPP to create the "Bullit in a Fishtank" effect.

Did you read up on ceramic rashig rings? If not, please go to the (long not mentioned) parent site. With the surface maximalization theory in mind, rashig rings get scourched there! And (with the wrong theory in mind) they are right.

But I'll let you in on a little secret ... I have obtained pure azeo with rashig rings ... in just 11 centimeters of packing. That's ... an HETP of 0.8 centimeters ... for rashig rings, really?

Another one: cut management benefits from reflux management, but HETP depends on reflux without management.

Solve the riddle and cut out a lot of crap.

You might even consider not to invest in SPP no more.

Regards, Odin.

PS: Sorry, can't seem to help myself of ... being a bit controversial. Hope you don't mind. I'll be over in Seattle and throw you some drinks to make up for energy depleted. Around July 11th. Or a few weeks before that ... let's discuss theory over a dram or two, three, four, while I am visiting New York and Pennsylvania!
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Re: Sight glass placement in a SPP-packed reflux column

Post by Hound Dog »

I have had that same sight glass just above lava rock packing for quite a while. I never experienced any problems with it. I used it there to watch for flooding above the packing to know when to knock the heat back a bit. I am just now trying SPP so I will see if there is a negative there. This is in a 3 inch column.
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Re: Sight glass placement in a SPP-packed reflux column

Post by Odin »

Okay, H, proof me wrong please! I am not just being an asshole. Trying to share my info, that's all. Love you all. Problem with the mss to solve right now. Seem to have the bigger impact. As always.

Odin out.
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Re: Sight glass placement in a SPP-packed reflux column

Post by T-Pee »

I also put my sight glass between the packing and the takeoff to watch for flooding. I believe it has helped me run the column as well as it can be.

My thread on the subject with video: http://homedistiller.org/forum/viewtopi ... =2&t=54029

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Re: Sight glass placement in a SPP-packed reflux column

Post by Hound Dog »

Odin wrote:Okay, H, proof me wrong please! I am not just being an asshole. Trying to share my info, that's all. Love you all. Problem with the mss to solve right now. Seem to have the bigger impact. As always.

Odin out.
Odin, your insight is highly valued and your experience here is par none. I am merely pointing out my observations. I have not gone through the process of tracking results as you must have. I look forward to further input from you on this.
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Re: Sight glass placement in a SPP-packed reflux column

Post by pulsetech »

From what I have noticed. Having the reflux condenser closer to the packing can make a big impact on stability and take off speed. I don't understand why yet.
my column is modular so I can add and subtract sections With little effort. I had one of my sight glass tee's from my flute without the plate on top of my packed section to get a look at the geysers. Had nothing but trouble getting the thing to stabilize. I had huffing and all sorts of problems. I thought it was because of the sight glass so I replaced the tee with a straight section of the same length. Same problems. Took the straight section out a and put the reflux condenser right on top of the packing and it ran so much more stable. This is in a 4 inch CM so might not be relevant
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