how does copper wool work in the column?

[Forest Beekeeper]

I have an 8 gallon reflux column still from Mile hi distilling with a 2" dia column.

When I started using it, I stuffed the column with copper wool and it worked great. I was routinely producing 184-proof drippings.

After a year I noticed the proof readings began to drop. I emptied the column and scrubbed every thing clean. The old copper wool was degraded and falling apart, so I replaced the copper wool.

But then it is only producing 140-proof.

One of my buddies says that it is critical that the copper wool be placed near the bottom of the column and at the top, leaving an empty space in the middle of the column. Is that true?

I just ran it yesterday, with about 8 inches of copper wool stuffed in the bottom of the column, and another 8 inches in the top of the column, leaving maybe 1 - 1/2 foot of empty space in the middle. This gave me 160-proof whiskey.

How do I optimize this to get the highest proof I can get?

[subbrew]

I have not tried this so am only talking from theory. But in theory you are missing out on redistillations having the open area in the middle. The entire theory of a reflux column is that the reflux coming down is heated by the steam coming up and the lighter (more volatile) molecules re-evaporate. At the same time the less volatile compounds/molecules in the steam give up energy and condense. Very little of that is happening in the open space in the middle.

I suspect that when you repacked the new wool in the column you did not have it even and it was channeling so you were not getting the redistillations you had originally.

[Forest Beekeeper]

... I suspect that when you repacked the new wool in the column you did not have it even and it was channeling so you were not getting the redistillations you had originally.

That is possible.

When I pack the wool into the column. I lay it all out. Roughly 8 inches wide and 25 feet long. Using bamboo chopsticks I roll it as tight as I can. The rolls are maybe 1/4" larger in diameter than the column. It takes a lot of effort for me to stuff the copper wool rolls into the column. I dont think I can get it any tighter.

I am not sure how to avoid there being any 'channeling'.

[shadylane]

How do I optimize this to get the highest proof I can get?

Pack the entire column to around 4 inches of the take off to get as many height equivalent to a theoretical plate (HETP) as possible.
How tight the copper mesh is packed has an effect on the abv, also how much power and how fast the take off is.

[Saltbush Bill]

As above the entire section needs to be packed with Rolls of copper mesh.
It should be packed tight but not so tight that you cant blow through the still easily.
Leaving a gap in the packing is defeating the whole purpose of the exercise.

[Forest Beekeeper]

Okay, thank you

[Dancing4dan]

When my packed column had to sit for any period of time the copper packing was removed and rinsed with hot water and allowed it to dry until next use. This significantly slowed the degradation of the copper packing.

[Salt Must Flow]

... I suspect that when you repacked the new wool in the column you did not have it even and it was channeling so you were not getting the redistillations you had originally.

That is possible.

When I pack the wool into the column. I lay it all out. Roughly 8 inches wide and 25 feet long. Using bamboo chopsticks I roll it as tight as I can. The rolls are maybe 1/4" larger in diameter than the column. It takes a lot of effort for me to stuff the copper wool rolls into the column. I dont think I can get it any tighter.

I am not sure how to avoid there being any 'channeling'.

With copper mesh you don't want to roll it too tight. You don't want it rolled too loose either. If it's rolled too loose, it can produce lower % ABV because it the rising vapor cannot interact with the falling reflux as it is intended to (like subbrew described previously). If it's rolled too tight it can cause the column to choke and flood resulting in poor performance (low % ABV again). I have not read or found a standard operating procedure for rolling copper mesh before. People say, "blow through the pipe, it's restricted then it's too tight". I've tried to get people to weigh a roll of properly rolled copper mesh so I would have a baseline to duplicate, BUT not all copper mesh is the same. Measuring the length of a roll also doesn't work unless the mesh is the same too. Some mesh is more coarse than others.

Stainless scrubbers are more finicky than mesh in my experience. No matter what I did, I could not pack my column with stainless scrubbers and get the column to perform consistently or stop flooding. For these reasons (and many more) I decided that 'random packing' is the way to go for me. Examples of random packing are SPP (spiral prismatic packing), Lava Rock, Ceramic Rings, Raschig Rings, saddles, marbles, ceramic spheres, etc... Simply pour the packing into the column, slap the column to ensure it all settles nicely and the column WILL ALWAYS perform exactly the same every single time. The key to random packing is sizing. If it's too small, the column will choke/flood. If it's too big, it can result in lower performance.

[shadylane]

With copper mesh you don't want to roll it too tight. You don't want it rolled too loose either. If it's rolled too loose, it can produce lower % ABV because it the rising vapor cannot interact with the falling reflux as it is intended to (like subbrew described previously). If it's rolled too tight it can cause the column to choke and flood resulting in poor performance (low % ABV again). I have not read or found a standard operating procedure for rolling copper mesh before. People say, "blow through the pipe, it's restricted then it's too tight". I've tried to get people to weigh a roll of properly rolled copper mesh so I would have a baseline to duplicate, BUT not all copper mesh is the same. Measuring the length of a roll also doesn't work unless the mesh is the same too. Some mesh is more coarse than others.

Somebody needs to experiment with how tight to pack copper mesh.
Here's a way to measure the pressure drop across the packing for reference and provide a PRV if the packings too tight.

[Forest Beekeeper]

Somebody

[BigSwede]

Somebody needs to experiment with how tight to pack copper mesh.
Here's a way to measure the pressure drop across the packing for reference and provide a PRV if the packings too tight.

I'm wide open to correction on the physics of the manometer setup you describe, but won't pressure differential vary significantly with power input and possibly the boiler contents themselves? If I suddenly crank up the power, wouldn't there be a spike in diff. pressure?

As a baseline for a given setup, a given wattage, then one could compare packing densities and restriction. But for Joe Blow to post "800g of copper mesh in 5' of 2" column is perfect" - might not be applicable to anyone else.

[shadylane]

Power would definitely affect the pressure drop across the packing, so the test would need to be done at a constant power level that matches the column size.

[BigSwede]

I've been rebuilding my rig after a long time-out, and your manometer suggestion has me thinking. Being a science nerd with a chemistry background, I like the idea of baselines, fixed references to compare variables one at a time. Standard science-y stuff.

With my 3" column down and empty, it'd be simple to drill and tap for a pair of 1/8" FTP ports. HVAC guys use handheld digital diff pressure gadgets like this one to measure pressure drop across a filter, for example. https://www.amazon.com/EHDIS-Manometer- ... B07L641Q7L

Two issues to using something like this: I haven't a clue about the range of diff pressure across a typical hobby column. This thing is +/- 3 PSI, which sounds like it'd be in the ballpark. Second, the lower column tap would need a loop that climbs to the top of the column before reaching the device, as any flooding or puking could otherwise send liquids into the device, and that could destroy it.

Or... just make a manometer as pictured.

[Flustered]

... I suspect that when you repacked the new wool in the column you did not have it even and it was channeling so you were not getting the redistillations you had originally.

That is possible.

When I pack the wool into the column. I lay it all out. Roughly 8 inches wide and 25 feet long. Using bamboo chopsticks I roll it as tight as I can. The rolls are maybe 1/4" larger in diameter than the column. It takes a lot of effort for me to stuff the copper wool rolls into the column. I dont think I can get it any tighter.

I am not sure how to avoid there being any 'channeling'.

With copper mesh you don't want to roll it too tight. You don't want it rolled too loose either. If it's rolled too loose, it can produce lower % ABV because it the rising vapor cannot interact with the falling reflux as it is intended to (like subbrew described previously). If it's rolled too tight it can cause the column to choke and flood resulting in poor performance (low % ABV again). I have not read or found a standard operating procedure for rolling copper mesh before. People say, "blow through the pipe, it's restricted then it's too tight". I've tried to get people to weigh a roll of properly rolled copper mesh so I would have a baseline to duplicate, BUT not all copper mesh is the same. Measuring the length of a roll also doesn't work unless the mesh is the same too. Some mesh is more coarse than others.

Stainless scrubbers are more finicky than mesh in my experience. No matter what I did, I could not pack my column with stainless scrubbers and get the column to perform consistently or stop flooding. For these reasons (and many more) I decided that 'random packing' is the way to go for me. Examples of random packing are SPP (spiral prismatic packing), Lava Rock, Ceramic Rings, Raschig Rings, saddles, marbles, ceramic spheres, etc... Simply pour the packing into the column, slap the column to ensure it all settles nicely and the column WILL ALWAYS perform exactly the same every single time. The key to random packing is sizing. If it's too small, the column will choke/flood. If it's too big, it can result in lower performance.

I use 1/2” Hobby Lobby “marbles” in my 51” x 2” column.
I have a short filter spool with 6mm holes under it to hold the packing up.
I used to use a copper scrubber on the filter spool because I was afraid of the marbles blocking the holes and I could get it to flood (or run as a fluidized bed at the top of the packing in my sight glass) pretty easily.
I stopped with the scrubber and it drains readily now and produces azeo throughout the run no problem.

I dump them into a brew bag and rinse them and set them in the shed until next time.
No degradation, no fuss, no muss.
I just have to be careful not to shatter any while dumping them into a the column.