Problems running VM

Vapor, Liquid or Cooling Management. Flutes, plates, etc.

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Matt64
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Problems running VM

Post by Matt64 »

I am having problems running our test vapour management column. The column is 2.8 metres high with an internal diameter of 64mm. There are 42 perforated plates in the column. On top of the column we have a reflux condenser and the vapour take off ball-valve sits about 30mm below this.

We measure the temperature above and below the reflux condenser.

The reflux condenser was modified recently as we were getting choking as the vapour tubes were too small, so the condenser now holds 8 x 13.6mm (inner diameter) tubes. Condenser length is about 400mm. I thought that this larger tube design would avoid choking.

Running the column today, the column gets up to about 77°C under the reflux condenser and sits around 25°C above it. Leave the column to get into equilibrium but after about 30 minutes, the temperature above the reflux condenser shoots up and the temperature below drops to 60°C and both temperatures become unstable. Liquid disappears from the bottom plate at this stage. Coolant water was gradually rising but was still at 25°C at this time. Heat input is constant throughout. With liquid passing by the reflux condenser, we switch off. I am guessing that choking occurred again.

When I ran this set-up previously a couple of days ago, with a smaller volume of liquid (for faster warm-up), I completed the equilibrium stage with no problems and opened the vapour take-off valve but even with it fully open, no vapour was exiting until I increased the heat input further. That started the vapour flow but was then too fast and I closed the vapour valve down but had lost liquid at plate 1. So the column became out of balance. No reflux condenser choking on that test run though.

So I am scratching my head and thinking:
- The column is highly sensitive to heat input. Very slightly too much and the reflux condenser is overcome. Slightly too little and there is not enough oomph to get the vapour to exit the port at the top of the column below the reflux condenser. It is very difficult to keep it in balance.
- Maybe perforated plates are not suitable for a 64mm (2.5") column? Maybe packing would allow the column to be more controllable and less sensitive?
- Maybe the 64mm diameter column is too narrow and over sensitive to heat input? Perhaps a larger diameter column would be less sensitive?

Would appreciate any thoughts please as to how I can resolve this.

Thank you!
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Re: Problems running VM

Post by greggn »

Matt64 wrote: Thu Aug 04, 2022 8:19 am
The reflux condenser was modified recently as we were getting choking as the vapour tubes were too small


If your VM takeoff is below your RC, what was happening when it was "choking" ?
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Re: Problems running VM

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Matt64 wrote: Thu Aug 04, 2022 8:19 am I am having problems running our test vapour management column. The column is 2.8 metres high with an internal diameter of 64mm. There are 42 perforated plates in the column. On top of the column we have a reflux condenser and the vapour take off ball-valve sits about 30mm below this.

We measure the temperature above and below the reflux condenser.

The reflux condenser was modified recently as we were getting choking as the vapour tubes were too small, so the condenser now holds 8 x 13.6mm (inner diameter) tubes. Condenser length is about 400mm. I thought that this larger tube design would avoid choking.

Running the column today, the column gets up to about 77°C under the reflux condenser and sits around 25°C above it. Leave the column to get into equilibrium but after about 30 minutes, the temperature above the reflux condenser shoots up and the temperature below drops to 60°C and both temperatures become unstable. Liquid disappears from the bottom plate at this stage. Coolant water was gradually rising but was still at 25°C at this time. Heat input is constant throughout. With liquid passing by the reflux condenser, we switch off. I am guessing that choking occurred again.
What is being descripted by your statements, is certainly not a VM unit, nor a CM or a flute, certainly not with 42 perforated plates at the hobby level..

Is this a unit you built or a purchased unit.. plus a picture of the unit setup would be appreciated as that will assist in helping figure out the issue(s)..

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Re: Problems running VM

Post by Salt Must Flow »

You say you're testing the column. Are you testing with water, a sugar wash or diluted alcohol?

That's excessively tall for a 2.5" ID column. My 3" VM has 6' of column. I've tried it and it works great with 5' too.

I wouldn't use any perforated plate in a VM column. The plates themselves could be causing the column to flood. I would switch to using properly sized Lava Rock as packing. It's cheap, readily available, simple to sieve to sort out the proper size and works absolutely amazing. I use 3-4 rolls of copper mesh at the base of my column then pour the Lava Rock on top. You want to eliminate anything that can restrict falling reflux from causing it to choke & flood.

I have always used a double wound copper coil for a reflux condenser and it knocks down even 5500W. It sounds to me like you're using a design similar to a common dephlegmator which is like a short shotgun condenser as a reflux condenser. I couldn't really comment on how those would work in this configuration because I've never tried it.

How do you heat the boiler? Gas or electric?

I think this is an easy fix.
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Re: Problems running VM

Post by Yummyrum »

42 plates in 2.8m means you have plate spacing of 66mm .
You mat have noticed that there are very few 2” plated stills around . One thing is common . The plate spacing need to be around 200-300mm at 2” diameter otherwise there is significant entrainment .Very few that made 2” plated stills ever said they were happy with them .

I wonder about your plate to column seal . I would imagine you have a long slide in plate tree . At 2” diameter , thats a lot of potential “gap” especially compounded by 42 .

I would also imagine that you have to run it pretty hard to get the plates to hold liquid . What power are you runing to keep the plates loaded .

Any chance of a picture of those plates . Maybe the down comers are too small .

To me , it sounds like you are aiming fir a Nuetral . I think packing is a better option
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Re: Problems running VM

Post by still_stirrin »

Everything Yummy said, plus 1.
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Re: Problems running VM

Post by bluefish_dist »

Even at small pressure drops per plate, say .015 psi, that’s .63 psi for the whole column. Quite a lot imho. I would just run packing instead of plates. I have run 2” packed at 1.8m and 4 or 6” at 2.4m, those configurations all ran well.

As yummy pointed out your plate spacing is quite small. I found 125-150mm worked ok. Shorter did not work well. You could probably take out half the plates and still make a nice neutral. Would have better plate spacing and still plenty of plates to reach azeo.
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Re: Problems running VM

Post by Saltbush Bill »

Sounds to me that its a combination of many things and that its plain out flooding.
Where did you get the idea to build something like this ?......any photos or plans we can see??
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Re: Problems running VM

Post by Matt64 »

Thanks to everyone for all the input.

Looks like packing on this particular column is the best option then. I can remove all plates but leave the bottom plate in place to hold the packing. What is the view on 6mm ceramic Raschig Rings for packing and what sort of life are they likely to have?

The reflux condenser at the top of the column is vented and this vent doubles up as CIP after each run. We are looking to run vodka on this still from a barley wash that is about 35% ABV. I want to ensure that the column is clean after each run to ensure no taint from the tails of a previous run. That was one of the reasons I did not go for packing, as I thought that plates might be easier to clean. After a run, we would back-wash the column with water to flush it, followed by a 0.5% citric wash to clean everything up, followed by a rinse. The ceramic Raschig Rings should withstand the citric wash fine.

No copper plates means much less copper contact though, so I guess I am going to need some copper mesh to the base of the column. Is there any information on how much copper contact is beneficial for cleaning up the spirit? The column is fed by a 250 litre copper pot that is heated by propane.

This is a pic of the internal of the previous reflux condenser. Don't have a pic of the current one at the moment but that holds 8 x 13mm ID tubes.
Reflux condenser
Reflux condenser
The column is 2.8 metres high with an internal diameter of 64mm. This is the top of the column, with reflux condenser on top, temperature probe on the right and vapour take-off port on the right. I know it needs a bit of a clean-up! We will sort that :)
Top of column
Top of column
This is a pic of the plates. Holes are 2mm diameter. The central hole is for the rod that spaces the plates out. These plates will now go into our growing museum.
Plate
Plate
Thanks again!
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Re: Problems running VM

Post by Matt64 »

I came across this comparison of different packing mediums at http://www.homewinemaking.co.uk/yabb2/Y ... 1394449319

The highest purity seems to be Spiral Prismatic Packing.
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Re: Problems running VM

Post by Matt64 »

Matt64 wrote: Mon Aug 08, 2022 6:36 am I came across this comparison of different packing mediums at http://www.homewinemaking.co.uk/yabb2/Y ... 1394449319

The highest purity seems to be Spiral Prismatic Packing.
They seem to be available in both copper and stainless steel.
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Re: Problems running VM

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Matt64 wrote: Mon Aug 08, 2022 6:30 am Looks like packing on this particular column is the best option then. I can remove all plates but leave the bottom plate in place to hold the packing. What is the view on 6mm ceramic Raschig Rings for packing and what sort of life are they likely to have?
I haven't worked with 6mm rings but with 8mm, but they should work well in the 64mm column.. as to "what sort of life" one can expect from their usage, should last for quite a while, but their downfall in that they break easily, and once broken up their efficiency drops, so handle them with care, especially when loading and unloading them.

But I have a major concern with using one of the plates as packing holder (if identical to the one in the picture), as it will cause the column to flood, it's not the proper design as packing holder.. a packing holder need lots of open space to allow both the vapor movement up and the cooled distillate to return without restriction..

A word on the plates, they were not design properly..

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Re: Problems running VM

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StillerBoy wrote: Mon Aug 08, 2022 6:56 am
Matt64 wrote: Mon Aug 08, 2022 6:30 am Looks like packing on this particular column is the best option then. I can remove all plates but leave the bottom plate in place to hold the packing. What is the view on 6mm ceramic Raschig Rings for packing and what sort of life are they likely to have?
I haven't worked with 6mm rings but with 8mm, but they should work well in the 64mm column.. as to "what sort of life" one can expect from their usage, should last for quite a while, but their downfall in that they break easily, and once broken up their efficiency drops, so handle them with care, especially when loading and unloading them.

But I have a major concern with using one of the plates as packing holder (if identical to the one in the picture), as it will cause the column to flood, it's not the proper design as packing holder.. a packing holder need lots of open space to allow both the vapor movement up and the cooled distillate to return without restriction..

A word on the plates, they were not design properly..

Mars
OK, thanks. so we can drill out the bottom plate holes to allow more vapour movement but still able to hold up the packing.
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Re: Problems running VM

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StillerBoy wrote: Mon Aug 08, 2022 6:56 am
Matt64 wrote: Mon Aug 08, 2022 6:30 am Looks like packing on this particular column is the best option then. I can remove all plates but leave the bottom plate in place to hold the packing. What is the view on 6mm ceramic Raschig Rings for packing and what sort of life are they likely to have?
A word on the plates, they were not design properly..

Mars
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Re: Problems running VM

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Matt64 wrote: Mon Aug 08, 2022 7:01 am OK, thanks. so we can drill out the bottom plate holes to allow more vapour movement but still able to hold up the packing.
Drilling out the holes to a bigger size will not be useful as the spacing between holes will still cause restriction..

The best holder in all the experiments made is a wagon wheel style of holder..

Picture below is what my holder looks like on my 3" packed with SSP.. it's made using a 10 gauge wire, sitting of the edge of the ferrule, and the packing, due to it's small size, is assisted with a small amount of ss scrubby loosely packed, or just enough so that the packing doesn't fall through..

In your case, the column being ss, some holes would need to be drill with some pin inserted, again 10 g wire would do the trick..

Mars
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Wagon wheel design for 3"
Wagon wheel design for 3"
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Re: Problems running VM

Post by Salt Must Flow »

You can also make your own by cutting away the inner portion of any Tri-Clamp gasket. PTFE gaskets are easy to Dremel away.

Now you can make one of those copper wire supports and install it like this:
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Re: Problems running VM

Post by Matt64 »

StillerBoy wrote: Mon Aug 08, 2022 11:13 am The best holder in all the experiments made is a wagon wheel style of holder..

Picture below is what my holder looks like on my 3" packed with SSP.. it's made using a 10 gauge wire, sitting of the edge of the ferrule, and the packing, due to it's small size, is assisted with a small amount of ss scrubby loosely packed, or just enough so that the packing doesn't fall through..

In your case, the column being ss, some holes would need to be drill with some pin inserted, again 10 g wire would do the trick..

Mars
Thanks for the info. Why use stainless rather than copper for the packing?

Our boiler pot and column tube is copper, so I am thinking that copper packing would also be used.
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Re: Problems running VM

Post by Matt64 »

I found this https://do-it-at-home.co.uk/en/distilla ... 21863.html

I calculate the volume of our column at 9 litres, so it's quite an expensive test and I don't know what the life of the copper spiral prismatic packing is.

Does anyone have any experience of the pro's and con's of copper v stainless spiral prismatic packing?

Matt
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Re: Problems running VM

Post by Salt Must Flow »

I've read that those who use copper SPP have said that since copper is soft, it supposedly crushes under its own weight at some point. Stainless SPP is much more rigid. There is data that says copper is most beneficial within the boiler, but I've always just use some copper mesh in the base of my column and never had any perception of having any lack of copper.

Most people that use SPP have reported that they do not need as tall of a column due to the effectiveness of SPP. You may not need as much as you suspect. I would search the site for 'SPP column height'.

Yes, SPP is very expensive. That's why I use properly sized Lava Rock. I keep pushing the Lava Rock faster and faster to compare my data with those that use SPP to see if it is worth the expense. I'm very happy with my quality and takeoff rate. It would take a significant increase in performance for me to justify the expense of SPP. I've even considered making it myself, but the wire alone is still quite expensive.
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Re: Problems running VM

Post by amh71 »

Can't comment on the copper but I bought his stainless version, works great and when I ordered it earlier this year he was the cheapest I could find in the UK by a very long way.
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Re: Problems running VM

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Matt64 wrote: Wed Aug 10, 2022 7:09 am Why use stainless rather than copper for the packing?

Our boiler pot and column tube is copper, so I am thinking that copper packing would also be used.
SS versa copper as an assistance to the holder for holding packing, first it's only used when their lots of copper in the system, otherwise copper would be used, and secondly, ss scrubby will do a better job because it will hold it's shape when hot whereas copper soften, and ss can be used many times over.. one has to be mindful of the weight the holder is holding, especially SSP, and one does not want much, just enough so the rings don't fall through, otherwise, to much packing on top of the holder will cause some interference with the vapor/distillate action..

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Re: Problems running VM

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Matt64 wrote: Wed Aug 10, 2022 8:03 amDoes anyone have any experience of the pro's and con's of copper v stainless spiral prismatic packing?
I don’t use SPP, so I don’t have practical experience with it. However I am a design engineer, so my reply will be relative to the design.

1) Copper is a more expensive material, so the packing will be more costly to acquire. Small gage stainless steel is common for wire welding so the wire can be sourced at welding supply houses. (advantage —> stainless steel)

2) Stainless steel is less ductile than copper making it more likely to hold the prismatic (formed) shape when made. Copper wire is more malleable, but will work harden when formed, adding stiffness. But repeated working it can initiate fracture. (advantage —> stainless steel)

3) Copper is 1.33 times better for conducting heat. This means that it will heat up quicker and retain heat longer than stainless steel. And for effective reflux action, you want the vapor’s heat to transfer to the condensate, not the packing. So, if the metal packing is absorbing and storing the heat, it will reduce the effectiveness of reflux process, albeit slightly. (advantage —> stainless steel)

4) Copper is a favored metal for distilling because of its chemical activity. It will form compounds which will eliminate, or reduce offensive constituents from the vapors (and condensate). (advantage —> copper)

5) Stainless steel is lighter than copper, so a volume of stainless steel packing will weigh slightly less than an equal volume of copper packing, assuming the same wire gage is used in the same prism form. (advantage —> stainless steel)

6) Stainless steel is less affected by chemicals, so cleaning with chemicals (caustics to remove organic compounds) will not affect it like it would copper. Stainless is attacked by chlorine, so it should not be used with stainless steel packing. However, the caustic cleaners will remove the build up the SPP can accumulate with use. (advantage —> stainless steel)

So, these points may seem minor in comparison and in most cases, they are. Source availability of either material may be a guiding requirement, however. Stainless steel prismatic packing is more commonly available and is quite effective in a packed column. However, copper in the still is very desirable and should not be disregarded. But I would sooner use stainless SPP and use a copper column and stillhead (my preferred solution).
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Re: Problems running VM

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Matt64 wrote: Wed Aug 10, 2022 8:03 am I calculate the volume of our column at 9 litres, so it's quite an expensive test and I don't know what the life of the copper spiral prismatic packing is.
Personally, I wouldn't touch copper spiral, and one of the main reason is they wouldn't last, and would need cleaning similar to copper scrubbies.. I've used ss ones, and have 36 x 3" column full, that I haven't use in over 4 yrs now.. there's a few issues with them, but weight is the main one plus cost.. compared to properly size lava rocks, they are equal in performance and purity, not discounting they hardly weight anything..

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Re: Problems running VM

Post by Matt64 »

My goal is 96% ABV from a 35% ABV wash. Concerns are to achieve purity while achieving a decent output rate.

My problems have centred around flooding due to poor plate design.

The pot and 2.8 metre column is copper, heated by propane.

i am going to remove the plates from the column, add a wagon wheel holder in the bottom, add a short layer of https://do-it-at-home.co.uk/en/distilla ... t-40g.html and then fill the column with stainless SPP https://do-it-at-home.co.uk/en/distilla ... 22358.html

My column diameter is 64mm. Does that SPP look too small? Concerned about flooding and output speed.

The reflux condenser sits on top of the 2.8 metre column, with the vapour take-off valve 25mm below that. I am thinking that the stainless SPP should be filled in the column to leave a gap above the SPP of 150mm to the vapour take-off valve.

What is the optimum output rate (litres per hour) I could target for this size column?

Would appreciate any views or flaws in my plan.

Cheers,
Matt
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Re: Problems running VM

Post by still_stirrin »

Gosh Matt, that stainless SPP is going to be expensive for your column (£20 per liter). It’ll get you to 190 proof, sure. But so would some inexpensive lava rock (scoria). You could get a 20kg bag from a garden center for less than £10? And it will be much lighter in your column too. And a single bag will fill your column several times.

Sometimes, “throwing money at it” isn’t the best solution.
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Re: Problems running VM

Post by Yummyrum »

IMO 2.8m is too long for a 2" column.
I think you'll find you can achieve what you want with as little as 1.5m.
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Re: Problems running VM

Post by Matt64 »

Since the column is 2.8m long, are there any issues that are possible to be caused when running it? I have worked on the principle that height = purity.

My preference for stainless SPP is the ability to keep it clean and free from off-flavours by running a citric and rinse back flush after the run. All nice and sparkly for the next run and no-where for any tails residue to hide.

Cheers,
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Re: Problems running VM

Post by Yummyrum »

Tails residue in packing doesn't manifest itself as a problem . As soon as you run the still next time , all that tails residue very quickly gets rinsed off the packing due to the solvent power of the fore shots and early heads that are pushing their way up the column as you hold it in full reflux while it equalises . Any tails residue ends up quickly refluxed back to the boiler . The packing is squeeky clean .

I hate tails with avengance and can detect the wiff of tails at 40 paces . :thumbdown:
I can confidently back up my comments above . No hint of tails will come off during any part of an Azeo run until all the hearts are done .

Being an anal tails hater , I would have adopted a packing wash regime , but it's absolutely not necessary :wink:

Regarding the column height . Can't comment from experience on that but concencus is that anything over 20:1 height to diameter is no gain
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Re: Problems running VM

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Matt64 wrote: Mon Aug 08, 2022 6:30 am
IMG_1543 b.jpg
I'm surprised no one has pointed out the size of your take off tube.


It's going to be a very slow run.
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Re: Problems running VM

Post by bunny »

Yummyrum wrote: Tue Aug 30, 2022 2:45 am Regarding the column height . Can't comment from experience on that but concencus is that anything over 20:1 height to diameter is no gain
There is also a consensus that anything over 20:1 height to diameter can add to take off speed. However, I don't know how to figure this.
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