fafrd wrote:So I've read through the CCVM thread end-to-end
Attaboy.
I'm planning to go with a 2" column but woukd appreciate to understand what this may mean when I get to trying CCVM mode - I undestand that 3" will be more efficient/powerful/faster, but what is that likely to translate to in terms of a 20-gallon spirit run?
In pot still mode, no difference. In reflux mode, at least 2.25x faster, maybe as much as 4x (I don't have a 3" but the numbers justify 2.25x, some reports are 3-4x). In this case it is the area of the pipe, thanks to that r^2 a 3"D pipe is 2.25x bigger than 2". But you will have to feed it that much more power, everything else being equal. In real volumes, for a good neutral expect 1 liter an hour from about 1800 watts as a good beginner goal from 2" and scale up from there. Depending on what you mean by 20 gallon run, prepare for clock shock, reflux runs take time. There are calculators on the parent site to model both pot and reflux runs that would be good to play with, hit "calcs" on the links across the top and you'll find em.
If product port is 2" and column size is 2", I understand that once the reflux condenser is raised, the reflux-to-product condensation ratio will be ~1:1 while with a 1" port it will be more like 4:1, but what will this mean on a practical level?
Hmmm, well if using it for neutral, not much, you'll rarely want/need less than 4:1 reflux ratio. Makes a bit of difference at the end if you want to collect tails. I dont collect tails for neutral, but I do for say rums made with reflux. Brandy I assume you would want the tails. A minimum 4:1 ratio will just take forever to run the tails out, because volume of product is already dropping. Maybe not a very big deal?
Also, occasionally with VM stills, things just dont go the way our understanding says they should. I would look and see if anybody has made a 2" CCVM with a 1" take off. It SHOULD work, but if it's new ground cant ever be 100% sure.
Also, if I use a 2" port but then use a 2"-1" reducer, will this behave any differently than a 1" port?
Yes/maybe. If the reduction is after the downturn, it practically isnt there. Especially if there is a small length of 2" going down. This is due to the fact that alcohol vapors are heavy, and as soon as they are out of the energy stream of the column they fall via gravity and are less affected by pipe diameter.
If the reduction is horizontal and right at the port....maybe, to my understanding there is some question to this. Maybe others have sorted it, but I've seen some varying reports that make it less than clear in my mind. I would expect some effect, though less than if you just had 1" coming straight off the 2" column.
Not a recommendation, but think of a still with an equal VM port, and going horizontal for some distance before reducing. At some point the vapor is cooling and shrinking enough to offset the slight backoressure of the reduction.
Side note, most discussions of VM theory dont address the fact that some tiny backoressure is caused by the space occupied by the reflux condenser, which would have the effect of splitting more vapor to the vm port. Especially if you have your RC stuffed with mesh to make it more efficient, you are increasing this effect. So there are a lot variables at balance, some trivial in some cases and significant in others.
1 last thought. Over the years I have upgraded almost everything. Boilers, power, controls, fermenters, pot stills, reflux stills (taller, various designs) etc. But I'm still using 2" diameter reflux stills. Would I like 3"? Hell yeah, every year when I do a big neutral run I swear this is the year. But in 20 hours I make so much damn neutral that I forget about it....until I'm out again! So, take that either way, you can get by fine with 2" OR you may well one day regret not having 3". Do you ever see yourself making 5 gallons of azeo at a time? Often enough that you dont want it to be a marathon? Go 3". Perfectly happy making azeo a gallon or 2 at a time? 2" is fine. Hell, when I started 2" was a big column, lots of people were still using 1.25 or 1.5", as many Russians are today. I thought 2" was future proof!