CCVM question

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StillCity
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CCVM question

Post by StillCity »

So I just did a water test/cleaning run of my CCVM still, after doing 2 vinegar runs both of which revealed some issues. (now solved)

However, when I tried out the reflux mode in this water run, I had some problems.
When the reflux condenser was all the way down, past the T junction (full reflux) everything seemed normal. However, as I moved the reflux condenser further up, the vapor began to get past the condenser, and leave the top of the column, but the temperature in the "lyne arm" stayed at 210F, and nothing dripped out of the worm.

Why could this be? am I doing something wrong, or maybe it's because it is water, and alcohol would act different?

diagram of my still attached:
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NormandieStill
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Re: CCVM question

Post by NormandieStill »

I would guess (based on science, not experience with a CCVM) that your reflux coolant temp was too high. Either it started out OK but warmed up as you started knocking back vapours or it didn't match the power of your stove and so vapour started to escape as the boiler charge reached temperature and started to boil off. I suspect that your movement of the coil was merely coincidence. Did you try lowering the coil again to see if that stopped it?

It's also possible that there's a blockage in your lyne arm or worm. Try blowing through them.
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Re: CCVM question

Post by OtisT »

Water vapor wants to go up. Alcohol vapor wants to go down. Otis
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Setsumi
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Re: CCVM question

Post by Setsumi »

Alchohol vapour behaves different. But things to look out for is the length of the shell above take off. And you will need to match your vapour speeds to your small diameter column.
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still_stirrin
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Re: CCVM question

Post by still_stirrin »

StillCity wrote: Fri Jul 30, 2021 5:57 pmWhy could this be?
Looking at your sketch, I would suspect that the flow resistance through the Lyne arm (3/4” ID) and the worm (3/8”) is greater than the flow resistance out of the top of the column. A fluid (be it a liquid or a vapor) will tend to take the “path of least resistance” with the exception being the force of gravity.

What I suspect is that if your Lyne arm was larger diameter (1” or even 1-1/2”) and more importantly, if your worm was 1/2” (or 3/4”) tubing that you could get some vapor at the product outlet for various settings of your reflux condenser/vapor management valve.

If you could upsize the plumbing, I believe you’ll have a better chance of production at the spout.

Also, I wonder if you’re pumping the water to the reflux condenser with a pump that has marginal throughput at the elevation of the condenser when it is raised up. It really doesn’t take much flow reduction for the reflux condenser in a CCVM to start “passing gas” when you raise the condenser higher (approaching the pump’s “deadhead” capability).

And with a coil of 1/4” soft copper, the flow path for the water is very restricted and so the pressure drop through it when the water is flowing becomes a significant limiting factor. Many of the CCVM stillheads here use corrugated stainless steel tubing that has a much larger inner diameter/flow area.

So, while your still “looks” like many builds here, your choice of materials (tubing with small flow area) could be the cause for your still not functioning properly. A good still design is more than a pretty picture.
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Demy
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Re: CCVM question

Post by Demy »

Setsumi wrote: Fri Jul 30, 2021 10:11 pm Alchohol vapour behaves different. But things to look out for is the length of the shell above take off. And you will need to match your vapour speeds to your small diameter column.
I agree with this. The alcohol steam is true behaves differently, I recommend a sacrificial race (with discard alcohol) to better evaluate the situation. You may need to extend the reflux chill or apply less power to keep up.
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Re: CCVM question

Post by Demy »

Furthermore, from the design there seems to be a problem (if I understand bad excuse me)
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StillCity
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Re: CCVM question

Post by StillCity »

Thanks all for the replies.

There was no blockage, and my reflux condenser water was exiting pretty cool. My problem may be the length of the shell above the T.

from what I have gathered so far, I think it is probably the differences in properties between water and alcohol vapors. Plus, I was running at full power, and 212F. With an alcohol spirit run, I doubt I would ever go to full power, and certainly not 212F. with a stripping run, maybe full power, but then it is in pot still mode, and the point is moot.

I will run a small batch of birdwatchers I have been fermenting, as a cleaning/test run and see what happens.

Again thanks for all the helpful replies! I appreciate yinz
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Re: CCVM question

Post by kimbodious »

It will be different with alcohol vapour
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Tummydoc
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Re: CCVM question

Post by Tummydoc »

The length of tube above the product take off should be long enough that it fully contains the coiled section of your reflux condensor when it is in the fully raised position. This isn't universally true if your coil is exceptionally long, but is true for 90% of our builds.
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Re: CCVM question

Post by Boozewaves »

I recommend putting scrubbies around the reflux condenser , this worked very well for me when vapour was escaping unless I ran at a slow speed , boil and rinse them a few times first

although I have never ran a ccvm that had a smaller size take-off from the main column
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still_stirrin
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Re: CCVM question

Post by still_stirrin »

Boozewaves wrote: Sun Aug 01, 2021 8:00 am… I recommend putting scrubbies around the reflux condenser…
… never ran a ccvm that had a smaller size take-off from the main column…
Wise words.

Scrubbies around the reflux condenser increases its surface area making it more efficient. —> GOODNESS.

And as noted, when the vapor takeoff is smaller (significantly smaller) than the column diameter, then the control sensitivity of the “valve” or “condenser valve” is much more limited. Ideally, a CCVM would have the takeoff branch at the same size as the column diameter so the resistance to flow would be negligible and the reflux ratio control would be solely due to the valve setting (and water/coolant flow rate).

Note that there is a lot of complex engineering to the way a CCVM operates although it is easy to set up and run. The tricky part is the fluid flow mechanics and thermodynamics that occur in the process….although you don’t have to be a mechanical engineer to build or run one.

And when you try to force the vapor flow into a worm product condenser, you’re getting most of the pressure drop in the coil. As a result, a shotgun, or at least a Liebig will mate better with the product outlet from a CCVM. The worm is actually “old technology” and many of the modern condenser designs are much better adapted to the VM and CM designs.

Sorry for the engineering ramble…I’ve had my “daily allotment” of my bourbon for this week. :lol:
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StillCity
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Re: CCVM question

Post by StillCity »

Update: running my first birdwatchers rn.
It works, but very slow (3 drops per second, max. Can't speed it up at all. Likely due to mentioned flow resistance)

It is coming off very clean at ~95% which surprised me. I would have thought that with my smaller diameter and column length it wouldn't get that high, but it is a nice surprise.

So here I am at 1:30 am watching it drip out, and sipping on coffee. This hobby is awesome![IMG]https://uploads.tapatalk-cdn.com/202108 ... 9bc6e6.jpg[/IMG]
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Re: CCVM question

Post by Corn Cracker »

My first thought is water distills at a higher temp than alchohol so the cooling of the coil is not sufficient for water, 2nd thought is the ⅜ copper needs to be at least ½ inch copper
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