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!