I am relatively new to this forum, so first I’ll give you a little background. About a decade ago, I became interested in distilling, and built my first (pretty crude) pot still. It worked okay for making small batches, and learning the ropes of fermenting a wash and running a still. Unfortunately, I had to move into an apartment with no yard to run the still in, and the still got crumpled and bent beyond repair in the move anyway. That was the end of my distilling career. Recently however I got a new job and one of the engineers I share an office with has been moonshining for 3-4 decades, and the other one has been home-brewing beer for about 5 years. Add to this the fact that my brother gifted me his practically-unused propane turkey-fryer, with a 6-gallon stainless steel pot, and it seems the ethanol gods were sending me a signal. I had decided a while ago that if I ever built another still it would be a column reflux still, as I really liked the idea of being able to make high-proof neutral spirits. My initial thought was to build a ‘valved reflux’ (liquid management) still, but after doing research here, it seems that a Vapor-Management still is the way to go as far as easier control (and pretty simple construction). I have attached a rough schematic of what I have in mind (obviously not to scale). I was hoping some of the more experienced guys could give me a sanity-check before I start buying materials. Is my understanding of the general layout of a VM still correct? Beyond the general, I have a few specific issues/questions (mainly revolving around specific dimensions) I was hoping to get some help on.
1- I have a source for large-diameter copper tubing that charges scrap-rates by the pound. They currently have 20-ft lengths of both 2” and 3” diameter tubing, and at the prices they charge (under $3 a pound) the cost to step up to 3” is not that prohibitive. Most of the designs I see on the forum use 2” tubing, I presume mainly for cost-savings. Is there a significant benefit to stepping up to 3” tubing? On the one hand, if there will be noticeable benefits to a 3” column I don’t mind the slight extra cost of larger tubing, but if it doesn’t benefit much I don’t want to spend money I don’t have to (especially if the cost of 3” vs. 2” fittings is large).
2- What should the other dimensions on my still be? I have them labeled in the drawing, any help is appreciated. I know many of these are best determined as a function of the column diameter (as addressed in Question #1) so I guess these answers will depend on the consensus for best column diameter.
A- Lower Column height
B- Total Upper Column Height (or size of coil condenser, if ‘C’ should be zero)
C- Dead space above tee and below coil condenser (is any necessary?)
E- Length from column tee to valve (does this matter? As short as possible?)
F- Length from valve to 90* bend (does this matter? As short as possible?)
G- Length of tube-in-tube product condenser (I assume this is a function of D4, inner tube diameter)?
D1- Addressed in Question #1 Above
D2, D3, D4 -Diameter of product-branch. I have read a lot of debate over the size of D2, and the impact it has on reflux ratios, and where to place the step-down from D2 to D3 to D4. A lot of this discussion seemed to be above my experience level. If anyone has any guidelines for what a typical setup would be, I would appreciate it. I am a relative novice with distilling, so doubt I will be doing anything too advanced with this still. I want a setup that can dependably produce relatively high-proof neutral spirits. Also, is there a standard diameter of the inner tube in the tube-in-tube condenser (D4)? I am thinking ½”? My moonshiner office-mate has a technique for building a solder-free tube-in-tube condenser, so I will have his assistance for that, but wanted to verify that ½” diameter for the inner tube is appropriate.
3- The product-branch valve- in most of the designs/builds I have read about on the forum here, I see this referred to as a “gate valve”. To the engineer in me, a ‘gate valve’ is a very specific style of valve (sometimes called a sluice valve http://en.wikipedia.org/wiki/Gate_valve" onclick="window.open(this.href);return false;" rel="nofollow ) that to me does not seem particularly suited to the purpose of the valve in the VM design (gate valves have a very non-linear relationship between fluid flow and percent opening/stem travel, are usually used fully-closed or fully-opened, not effective for throttling/regulating fluid flow). Do you guys actually use a gate valve (and if so why?) or do you typically use a more common (globe or needle) style valve and just refer to it as a gate valve? Is it safe to use a brass valve for this, or is the presence of lead in the brass alloy an issue (if so, I guess that means you have to use a stainless valve? Any good sources for this?).
4- The coil reflux condenser – Are there any good tutorials for building one, ideally that address both dimensions and construction techniques? I have a fair bit of experience bending tubing for fuel/brake lines, but not much working with small diameter copper. Is ¼” the standard used for these? Any other advice/tips/tricks would be much appreciated.
5- At some point, I may want to have a pot-still for making something other than neutral spirits (a friend has a very cheap source for raw molasses, and I LOVE dark rums). If I remove the column packing and the coil reflux condenser (and replace it with a cap), would I be able to use my still as a pot-still with the ‘gate-valve’ fully opened (ie all vapor goes through tube-in-tube condenser, the only reflux being what occurs along the walls of the column)? Or is this one of those thing that’s works in theory but in practice is not so true? If not, no big loss, I can always build a dedicated pot-still head for this boiler down the road.
I apologize for the long and wordy post, but I have a lot of questions and want to make sure I do things the right way the first time. I appreciate your patience in reading through this and welcome any thoughts, comments, suggestions, criticisms etc you may have to offer. Thanks!!