Boka Reflux Return

[bearriver]

My boka had a 90 degree takeoff from the tower (before and after pics included) and the top of the takeoff fitting was only slightly below that of top of the top plate. It ran fine, but I knew that I wasn't actually getting the maximum takeoff rate figured out. Small amounts, guessing 25-35% of the total distillate would splash over the top plate no matter what I did. Worse yet, there was terrible channeling under the bottom plate which required a centering ring. I know this from pouring alcohol down the top of the leveled head in my sink, and observing what went where.

Now to correct my error... I could have sized down and angled the initial takeoff tube before the needle valve. But I felt like doing it another way and here are the pictures. I used Hookline's http://homedistiller.org/forum/viewtopi ... =1&t=18873 as my inspiration

The results were fantastic. The head strips much faster and can now be clamped directly to the boiler without the needle valve. In pot mode a small amount of vapor slips into the takeoff, but the liebig throws it down before exiting the still. The lack of overflow splashing allows me to figure max takeoff rate, and thus the RR. In reflux, the returning distillate is perfectly centered above the packing while the overflow reservoir behind the valve is only 1-2 ml I might even add a little SS scrubby to make that volume even smaller. I also insulated the takeoff tube with lots of pipe insulation then wrapped that in electrical tape, just in case your wondering what that synthetic crap is.

[Hound Dog]

Pretty slick.

[Condensifier]

Good job and it looks great, too.

[rad14701]

Very nice modification... I've been considering a similar solution for my LM heads to reduce the possibility of choking and flooding... In fact I need to rework one head anyway and will definitely implement the reflux bypass circuit...

[bearriver]

Thanks everyone. Yall seem less like strangers everyday.

I am looking forward to seeing what you will come up with in the future Rad. The stills in your signature links are my first suggestion to friends and members who want a manageable sized rig.

[aj2456]

without a doubt one of the most refined boka design's ive seen in my short time on this site, if i hadnt already built a pot still head i would be shamelessly copying this modification

[W Pappy]

Nice work thar br I am really considering this for my next build with a few changes in the column.

[bearriver]

It was super easy. l only used very basic tools everyone probably owns. The hardest part was getting the angled holes drilled into the 3" pipe.

First I eye balled the holes with my drill, then honed out the angles correctly with a chainsaw file. Not one angle or length was measured to do this mod. Just fit, file, fit, file rinse repeat. Once everything dry fit, it was soldered up.

[Tal]

Nice!!....very rewarding at the end I bet.....probably attract a Goldilocks or two with that!

[apdb]

Is this a good mod for a Concentric (Rads) style condensor in 2" with 3/8" takeoff?
I'm ready to start soldering (longest build in history) but for a couple more bux this seems like a smart add on. In my build it will also move my product cooler (liebig) to a vertical position in reflux mode saving space. Switching to pot mode sure gets easier too and it allows full removal of SS valve. I was thinking that I could reduce the reservoir down from 2oz by adding in a return but after reflecting on it, how might that effect the potstill mode? Maybe I'll leave it as is.
Aaron

[BigSwede]

The modification looks excellent! But I'm trying to understand the original problem.

...and the top of the takeoff fitting was only slightly below that of top of the top plate.

Did you mean the top of the bottom plate? If I understand correctly, you had excess pooling and the valve was too high, and angled improperly, to drain the collected condensate? Smearing?

If so it looks like an ideal solution, and maybe an angled takeoff like that should almost become standard for a slant Bok. And I really like the reflux return.

From a physics POV, I think an LM collection system should have an absolute minimum horizontal component, and rather should turn down as quickly as possible, to get a little head pressure on the needle valve. A couple inches of 1/4" or 3/8" copper isn't going to hold much, and as soon as that's gone, what comes after is going to be sweet, assuming fores are gone.

[YHB]

Variation on a theme;

6.JPG (8.02 KiB) Viewed 3813 times

Reflux return built into a needle valve.

Yes to everything Bearriver said, the reflux return works a treat.

[bearriver]

@Apdb: Pm sent

@ YHB: You are a crafty sort. That is a mighty fine modification you got there. I believe that this type of mod markedly improves a basic LM design, and is worth while for anyone running an inline rig.

@ BigSwede: There were several added benefits. The by far largest one was this: The reservoir that the bottom plate creates would splash overflow onto the packing. Even with my 1/2" takeoff valve wide open. It was impossible to figure an exact reflux ratio because it could not run at zero/no reflux . Post mod allows true pot still operation, and allows me to calc the exact RR.

Because of this, when running as a pot you have to remember to pack the liebig with scrubbers or add a vapor lock after the needle valve. Otherwise vapor will escape out of the takeoff as there is no pool in the plate above it to act as a vapor lock.

Still @ BigS Of all the reasons that drove me to do this mod, smearing wasn't one of them that I considered till it was done. My records show I have been getting slightly tighter cuts after implementing this mod. BUT, that could have easily been caused by cleaner ferments. Lastly you are correct, as I misspoke and you still got what I was trying to convey . The top of the bottom plate was below the level of the top of the takeoff hole/tube. It was a design error on my part, and I'll bet most people running a boka do not have the issue. You see, I speak 2 languages which are English and bad English. Apparently when I wrote that I was speaking the latter.