Newbie Theory on Column fittings

[Garand69]

Hello all,

After reading DAD300's thread on Condenser Controlled Column stills, I have settled on that variation of the VM design. I am a huge fan of the K.I.S.S. concept and it fits well in those parameters. While my heart was set on a 3", the added cost of copper has me settled on a 2" w/ Keg Boiler for getting my feet wet.

My question is regarding the fitting at the point of vapor take off. There are many possibilites but most use a T fitting of one variety or another. From what I have gathered so far here, any horizontal area at this point on the still can collect small amounts of distillate, which could contribute to smearing..... yes?

Keeping things as simple as possible, I was considering using a 2" 45 deg Sani Wye fitting instead of a 2" T. With the takeoff angled down, all I would need is a reducer, eliminating one fitting (Wye -> Reducer vs. T -> Elbow -> Reducer). At this point, I'm sure it would suffice just fine. Cost wise, it would be the same-ish because of the increase in cost of the Wye, but simplicity and less joints are my goals.

The question on theory is not whether it will work as a still, the question is will it improve/degrade still function in any way.

With the takeoff angle down, there would be no place for distillate to collect which should make cuts cleaner with less smearing... Correct???
Reflux should be unaffected or slightly less because the condensate in the horizontal portion of a VM still isn't really counted on for reflux or is it? With the Condensor Coil all the way down, the take off point should be effectively closed off, and anything that did get by during initial full reflux would be discarded anyway.

While I am intending to run it angled down, I also have a question about angling it up and if their would be any advantage to that. With it angled up, I would assume the reflux ratio would be slightly higher with all else being the equal because a certain percentage would fall out of vapor and be reintroduced to the column, is there an advantage/disadvantage? This variation would also leave less area for condensate to collect, decreasing smearing issues as above, but would add another fitting unless you could find a 2" - 1/2" Reducing elbow.

And now last but not least... Because the takeoff is essentially a mitered 45 degree joint, the area exposed to the column is greater than if at 90 deg. With a 2" pipe, you are adding about 1.5 sq inches to the area at the column with all gains in the verticle plane. Would that decrease the efficiency of the column to separate distillates because with all else being equal the column would be effectivly 1/2" shorter? And/Or, because of the extra height of the opening, would that allow a less pure distillate because vapor is being collected from a taller section of the column? Would it decrease the time for a stripping run any amount due to the slight funneling affect of the increased area??

Sorry for the ramblings ... just stuff swirling around in my head as I prepare to hit the plumbing supply house today.

[humbledore]

I say try it and see. Personally I don't think it will function any worse, might be better. 1/2" here or there will not make a difference. No pooling, that might be an improvement. I would not angle upwards. That is applicable to pot stills not relflux stills AFAIK. The idea is to get the vapor to drop.

[Prairiepiss]

In a VM still. I would make the y so the output is up. If you place it the other way. Falling reflux liquids can and or would fall into the takeoff. You don't want that. You want the falling reflux to go back down the packed column. Not down the takeoff. You just want vapors going out the takeoff.

Now I'm not sure how good the vapor splitting will be? Since you are working off the theory the alcohol vapors are heavier the water vapors. You want the alcohol vapors to spill over into the takeoff. To eventualy be kinda pulled into it by the slight vacuum created by the condenseing vapors. And you want the water vapors to shoot past the takeoff to the reflux condenser. Since the takeoff is angled upwards. It might not split the vapors good. As they might get cornfused as to where they should be going. Just thinking outloud.

Only one way to find out. Build it a try it.

[heartcut]

I agree with PP. Good fitting idea for a CM type takeoff, though.

[DAD300]

Hmmm... I see both side to this.

I assume your trying this because you have it? It's a nice expensive fitting. I like the idea of using what you've got! I'm a cheap bastad...

Angled up would prevent stray reflux from running down it.

Angled down would allow min reflux when desired. Using it in the down position also eliminates the need for an elbow to get the product away from the column.

My gut says angled down...can you try it without soldering it in? I would.

Just make sure your reflux coil can go below the bottom of the take off by at least a few coils.

If you soldered it in and found it too large, it is fixable. Add a permanent or temporary plate to the inside that makes it a round 2" hole, that your reflux coil can still get below.

Or add a curved thin plate to the side of the reflux coil, that moves with the coil.

The shield would ensure no reflux down the takeoff.

I think you'll find the coil as a valve so effective that there won't be a problem.

Either way let us know...

[Bob Loblaw]

Hey Garand - not sure what the right approach is here. I'm in the midst of building a still similar to what you propose (2" condenser controlled) and came across this thread so thought i'd say hello. I'm using a 2 x 2 x 2 tee on the takeoff with a short (4") arm. I wanted to have a set of stainless ferrules right after the Tee so that I can twist the take-off arm and run in pot still mode. I can't go much shorter than 4" with all that hardware on there. Hopefully it won't give me too bad of smearing problems. I imagine it has to be better than if you put a reducer in that horizontal path.

[Garand69]

Thanks for your feeback folks, I'm going to try and score 2 and do some side by side testing. But I'm still leaning agled down.

[S-Cackalacky]

The CC column is my planned reflux still build. I'm hoping you will be updating this thread as your build progresses. I'm very interested in hearing about your results.

Thanks,
S-C