Boka-NixonStone theory help- long background

[Gatsby]

I'm an old experienced newbie.
I built my first still about 54 years ago, and first successful one about 4 years later. The pot was a 10 gallon, nickel plated copper, restaurant coffee maker, pre-heater in its previous life. The column was 3" copper tubing, about 30" tall filled with broken up wine bottles. I had a water fed coil inside the top of the column which then necked down through some fittings to a collection tube. I don't remember having any condensing cooler other than just air on the copper. It was propane fired.
I made some drinkable stuff, one time hitting a perfect stars alignment; but that's another story. Having achieved some some proficiency I quit doing that for the next 40-45 years?.
Okay. I now have a 1/4 barrel beer keg, 36" of packed 2" copper and a bunch of heads I made and played with a few years ago. I'm ready to settle on two configurations, a necked down bent top feeding a shotgun condenser, (pot still); and either a Boka-Nixon-stone type or just a short section of column with a cooling coil to insert between the column and head which would make it much the same as I had all those years ago.
So, in the Boka or N-S, the liquid and vapor are constantly passing each other at, or near, a collection point, and the collection rate is controlled by a valve. And if I understand it, that collection rate relates to the purity of the product.
Using the other plan, ( don't know what that's called), with a cooling coil atop column packing, and collecting only what goes above that, all of the commingling happens below that coil. The collection temp can be exactly monitored.
Is one vastly superior to the other, and if yes, how/why.

What am I making?
I have an interest in rum right now and I can do that with just the pot, but my interests and attention wander.

[still_stirrin]

...So, in the Boka or N-S, the liquid and vapor are constantly passing each other at, or near, a collection point, and the collection rate is controlled by a valve. And if I understand it, that collection rate relates to the purity of the product.

Both the Nixon-Stone and Bokakob are liquid managed (LM) reflux stillheads. They regulate the reflux ratio (and consequently the purity) by returning a portion of the condensed vapors to the column as reflux. Only a portion of the vapor produced and condensed by the reflux condenser (which is a necessary part of the stillhead) is actually collected at the product outlet....the rest returns to the column. The N/S head simply is offset from the column so you can build a liquid collection cup below the vapor inlet, which comes in frm the side. On a Boka, the collection cup is the bottom slant plate that has a tube piped outside of the column.

My combination LM/VM head uses a concentric liquid collection cup. It is annular, that is around the vapor tube which comes up the middle of the column. Like the Boka, the liquid product outlet taps into the condensate collection cup and liquid not drained (to the product vessel) spills back over the inner tube to the vapor tube path back to the column.

All of these regulate the reflux ratio, enhancing purity with the increase in reflux.

...Using the other plan, ( don't know what that's called), with a cooling coil atop column packing, and collecting only what goes above that, all of the commingling happens below that coil. The collection temp can be exactly monitored.

Here you’re thinking of a coolant or condenser managed (CM) reflux stillhead. The vapor reflux rate is determined by the cooling power of this condenser as a function of vapor production, which is proportional to the heat input. The CM stillheads are common in old school “cross-tube” reflux stills where a couple of tubes pass through the column. These types of stills are better at producing lower purity, higher flavored spirits tha the LM’s, which are great for neutral production.

Also, CM’s are more tricky to operate because you have to balance the coolant flow rate and heat input while getting the output flow desired for your operation. Minute variation in water flow rate can dramatically affect the purity of the product. So, they are difficult to maintain a steady flow and purity.

...Is one vastly superior to the other, and if yes, how/why.

What am I making?
I have an interest in rum right now and I can do that with just the pot, but my interests and attention wander.

So, for a full flavored spirit like a rum or whiskey, the potstill is often favored. Elaborate CM’s such as a plated “flute” are also often used for commercial full flavored spirits. But the potstill is a hobbiest’s preferred tool because of simplicity of build and easy of operation. But, in order to get the distillate proof up to cask strength, it is often adviseable to do 2 distillations, once as a strip and the final as a spirit run. This will get you to a collection proof of 125-135 proof which is ideal to casking.

The good think about starting with a potstill is that it is a great tool to have in your toolset. It is ideal for quick wash strips and it also will produce full flavored products.

And to grow from there if you desire to make cleaner, higher proof products (vodka, gin, etc.), then you can add a reflux stillhead in the future. Personally, I prefer the vapor managed (VM) reflux head because it is the easiest to run. Once you set the VM valve, the reflux ratio will be managed automatically, holding the proof for you throughout the run. Also, the VM is very good at compressing the tails the the very end of the run, giving you a fatter hearts section.

There is much more discussion of the different types, operation, and advantages in the Column forum.

I hope my discussion has helped you understand a little. Good luck with your learning processes. There is so much info on this website you’ll be amazed.
ss

[acfixer69]

Very nice answer still_sturrin. Read the whole thing and followed like a puppy. Sure wish I could write like that. Soon as my fingers start to type my head starts thinking about where's the key.

[Gatsby]

Very nice SS, thank you.
I guess what stands out for me is the control factor.
I'll do more reading on VM.
You mention your design; is it available?

[still_stirrin]

...You mention your design; is it available?

I don’t have a specific build thread for my stillhead, although I have posted fotos and discussion in several different threads. So, perhaps a build thread would be appropriate.

Of note, if you search DAD300’s CCVM, a condenser controlled vapor managed reflux stillhead, you’ll see much discussion on that design too. It is a relatively easy design to build with a minimum of parts. Yet it takes advantage of the “vapor valve” to regulate the ratio of vapor that gets returned to the column vs the vapor that advances to the product condenser. It is a relatively new design but many members here have accepted and use it for their reflux head of choice.

However, since the “valve’s” function is somewhat controlled by the coolant flow, it is a hybrid of the VM which is not completely independent of the coolant flow or temperature.

Indeed the VM is very good at maintaining a high reflux ratio through the hearts and back end, although the LM is very good at compressing the heads for front end separation. So, my combination LM/VM gives me the best of both designs. So, I will put together a design theory and build discussion to help explain it.

One thing, as I previously stated, the stillhead uses a concentric LM collection cup which is attributed to Rad14701. Unfortunately he doesn’t participate here any more, but the concentric design is a great design and easy to build and operate. So, you can search for Rad’s concentric apartment still and you should find a few threads discussing it. I have a slide which describes the advantages of the design, again which I will post in my build thread.

In summary Gatsby, I think you need to evaluate what products you are planning to produce. Understand what your building skills are and what your build budget is. All of these factors are important to the selection of design you choose to build.

More to come....
ss

[StillerBoy]

the stillhead uses a concentric LM collection cup which is attributed to Rad14701. Unfortunately he doesn’t participate here any more, but the concentric design is a great design and easy to build and operate. So, you can search for Rad’s concentric apartment still and you should find a few threads discussing it.

I'm an advocate of the concentric.. relatively simple to build (those not a simple as the CCVM, Dad concept), and very versatile in its operation..

My 3" concentric, also have one in 2" and 1.5".. viewtopic.php?f=50&t=66917&start=60

I have attached the threads on the concentric, which was brought to the attention of the members here by Rad.. just some threads to get you started..

Rad's thread.. viewtopic.php?t=36382

The first concept of the concentric.. viewtopic.php?f=16&t=8046

Other threads on the concentric.. viewtopic.php?f=50&t=42206&p=7261234&hi ... c#p7261234

Operating a LM.. viewtopic.php?f=50&t=42206&p=7261234&hi ... c#p7261234

Using Lava Rock for refluxing.. viewtopic.php?f=17&t=42499

Mars

[still_stirrin]

Thanks Mars. That a great list of links to review. A lot of great discussion there.
ss

[Gatsby]

Wow! I've read all the links and find myself paralyzed with information overload.
The Dad300 stuff was/is riveting.
Exactly where each piece of info that has stayed in my old head came from is gone but I have a string of tabs on my browser as reference. The discussion on LM that talked about smearing verbalized the thoughts I had when I started this topic.
I think the system that offers me the best visualization of what works is VM; and maybe the Dad300 method of control is one I should try.
I'm not limited in ability to build, CNC machining is my main hobby, but I do have financial constraints; can't see myself buying a big piece of 3" copper.
If I were to construct a new VM head, wouldn't it make sense to angle the takeoff upward a bit. And I'm a bit foggy about the takeoff size and possible necking down, and where a hardware gate might be, assuming I didn't use dad300 method.
Uber-thanks for the help.

[StillerBoy]

A word of advise.. start by taking/making notes..

example: when reading a thread on concentric ( or whatever other matters), say the reflux condenser (in this example), note the tread title (and make sure you have saved the thread's url in a folder somewhere), next who posted and what info was relevant to the condenser, etc..

By working in this manner from notes, having to remember where, who, what info, become non relevant..

Mars