Modular VM Column Design Questions

[freestyletrev]

I’m looking at building a modular VM column for neutral spirits. I currently have a 10-gallon pot still, shown below. I’ve researched a good bit on this site and others for design inspiration. I have several questions before getting deeper into my design. To preface a few details:
• I plan to upgrade to a 15-gallon keg eventually.
• I’m limited to about a 70” column height with the keg, unless I poke through the ceiling and into the rafters (which is an option). This leaves
about 40-46” of packed column length as designed.
• I’m currently heating with propane but might move to 220v electric heat when I build the keg boiler.
• I’m going to use stainless steel SPP for my column packing.
• My current Liebig that will be used as a product condenser is 1” over ¾” at 36” long.
• I will use scrubbers stuffed in the top opening of the reflux condenser. It will have wire spiraled between the water jacket and inner tube.
• I might build a concentric LM head to make this into a hybrid LM/VM column in the future.

Pot Still.jpg

I did some rough sketches (not everything is to scale) in AutoCAD on what I have planned. I want a modular build so I can easily upgrade in the future. I want a concentric reflux condenser for ease of cleaning. I plan to use copper for most of the column (if not glass) and reflux condenser. I will use a several SS Tri-Clamp fittings in the design.

VM Only.jpg

VM Only 2x1 Tee.jpg

VM-LM Hybrid.jpg

With this in mind, I have a few questions for the more experienced:
1. Would a 2” or 3” column be better in the long run with larger 15-gallon batches? I know 2” suffers with takeoff speed, but my column height
can’t be much more than 40”. From what I’ve read, less than a 20:1 ratio is okay with SPP.
-- If I move to 3”, I will use SS tubing for the column.
2. Would it be beneficial to have the top 12”-24” of the packed section of the column as glass to monitor the SPP?
3. If I keep the 2” column, is it sufficient to split from the 2” column to 1” valve section, 1” to the reflux condenser? I thought about a 2” x 1”
reducing tee to expand the reflux vapor path to 1.5”. Would either tee setup be okay for a 3” column?
4. Is a ball valve okay or should I switch to a gate valve for better control?
5. How much of the column should I insulate? If I go with some glass, should I leave like a ½” viewing window through the insulation or leave it
uncovered completely?
6. Will a 13” concentric/Liebig reflux condenser be long enough or should I increase this slightly and reduce my packed column height to ~36”? ---
--Would a coil/double helix be better?

Sorry for the long post, but I appreciate any feedback!

[Salt Must Flow]

1. “In the long run” 3” would be better than 2” in my opinion. That would be 5’ of packed column (perhaps shorter with SPP, but I’ve never used it). Height of packed column is the key to a good reflux column. 2” is half the speed of 3”. I started with a 3” and somewhat recently upgraded to 4”.
2. You don’t need glass in the column, but many use a sight glass beneath the vapor take-off.
3. For a 2” column, a 1” vapor take-off valve would work (even 3/4" is adequate). I have a 1” gate valve on my 3” VM. I would not reduce to 1” to the reflux condenser. Stick with 2” to not impede its ability to condense vapor.
4. Gate valves are ideal.
5. I insulate all of my packed column. If I had a top section that’s glass, I’d probably leave it uninsulated so I can see what’s going on.
6. A Liebig condenser is not typically used as a reflux condenser. The most common reflux condenser is made by winding a copper coil, ideally 2 coils. That or a single coil with a Cold Finger in the center.

I would re-draw this while keeping every aspect of it as simple as possible. For instance if you’re going with a 2” column, I’d use a 2” short tee and a 2” copper coil reflux condenser.

The vapor take-off can be larger or the same diameter as the take-off valve. After the take-off valve, there’s no need to increase the diameter just to reduce the diameter leading to the product condenser. I would do whatever I can to reduce the length protruding perpendicularly from the column.

For the product condenser, especially a Liebig Condenser, length is ideal for stripping runs. When heating over flame, greater length is highly recommended to keep product & potential vapor from the flame.

DEFINITELY upgrade to electric. Electric is more precise, repeatable and MUCH safer in my opinion. By doing so would allow the boiler to sit as low as possible, allowing for a taller column and more packed column. Why design this column around a gas burner just to upgrade to electric later and adding more packed column? A well designed packed reflux column makes the most of the height available. Inches do count!

There’s a link in my description for a 4” VM build that might give you some ideas.

[Salt Must Flow]

For instance using a Tee like this would help make the VM head more compact. Fewer fittings. Shorter the tee leaves more height for packed column below and reflux condenser on top. The shorter vapor take-off helps make it so that you don't end up with 12" of connected fittings protruding from the head.

VM Short Reducing Tee.jpg

[Yummyrum]

Agree with what SMF is saying .

I think it would be a good idea to modify your existing Liebig by adding a 1” triclamp coupling as shown below.

IMG_3618.jpeg

Then you can go straight from the tee through a 1” valve , add a 1” 90° and connect to your Liebig instead of using reducers to join into your liebig after the valve . It will also significantly reduce the side load , something else SMF mentioned .

As for using a concentric RC , IIRC Rad come up with that idea to make an easy to build stove top still . I really don’t think it is an efficient use of height or material and while it might do OK with a 1.5” still running 1000-1500w , you would be far better off winding a copper coil …….especially if you are considering 3” .
Even with a 2” , you’ll be running it closer to 2kw unless you like long days .

Regarding LM/VM
I made mine that way . Used LM twice and have just ever used VM after that as it is soooo much easier .
If you have VM , LM brings nothing to the party .

[shadylane]

6.Will a 13” concentric/Liebig reflux condenser be long enough or should I increase this slightly and reduce my packed column height to ~36”? ---
--Would a coil/double helix be better?

My 2 cents.
A "coil" AKA dimroth condenser would be a better option than a concentric RC.
Almost everyone uses a coiled condenser for reflux for a reason. It can be shorter, cheaper and easier to build.