VM column, SPP, HETP and reflux ratio musings

[needmorstuff]

If I build a 3" column - with a 3X2X3 Tee - 2" inch reduction into a 1" gate valve. and have 48" of SPP packing.

say the spp hetp is 1" (open to correction but let's go with it)

I have a theoretical 48 plates.

If I open the gate valve a little to let fores and heads out at a few drips per second - is it reasonable to say reflux ration is around 95%?

then if I open gate valve fully is it reasonable to say the reflux ratio is reduced due to the 1" restriction of the gate valve - so 33%? as 1 inch is a third of the 3" tube to the condensor?

and if that's the case are my effective plates reduced to 16? so I can run the gate wide open and still have 16 effective plates.

[bluefish_dist]

You are over thinking it a bit. Wide open your reflux will be about 10:1. 1" opening is .78in^2, 3" = 7in ^2. So about 10:1. Which will probably work fine for neutrals as I have found I never run wide open. On my column which is 4", I run a 1" valve and never open it all the way. So the setup you propose will work.

IMHO the actual number doesn't matter, what matters is does the column do what you want. Ie will reflux be enough to make azeo. Yes it will. Will you be able to run it wide open and hold azeo, probably not. So the valve will cover the ranges of what you would want to produce. Now if you were doing whiskey, that would be too high of a reflux rate.
Running whiskey I run a 2" valve on a 6" column and it gets in the range I want (130-150proof) with 2 plates. I also have a 3" reflux condenser, so that has helped lower the reflux rate. I do have a 3" valve, but have not used it as I have not found the need. Also higher abv washes will require lower rr if you are making whiskey.

1" hetp might be possible, but I tried some SPP and was never able to get it to work that well. The stuff I had was over 4" hetp. So I went back to scrubbies which is about 4".

[needmorstuff]

just making neutral, i think i would just run a pot head for anything else and just run it twice.

i have had good results with spp on my 2 inch x 24 inch CM. got me a bump from 92% to 95.5%.. scrubbies certainly cheaper though. just thought for a 48" column the spp would guarantee the ability to get azeo and maintain a good output rate.

[bluefish_dist]

More plates is faster for sure. I recently added 2 ft to my column and it runs better. It was 6 ft, and now 8 ft, so 19 to 24 plate equivalents.

Where did you get your SPP?

[needmorstuff]

polish guy off eBay. I can link you up if you want