• Advertisement

Reduction Of Smearing and Alternative to Boka Plate "Tab"

These usually have the means for returning the spirits to the column and usually allow metering of the take off to help in the reflux.

Reduction Of Smearing and Alternative to Boka Plate "Tab"

Postby YHB » Mon Oct 24, 2011 5:56 am

Hi

I recently posted the design of a home made needle valve that takes less than an hour to build and is based on a the use of a stainless steel bicycle spoke.

I had a good response with many people joining in the discussion. The major point of constructive criticism related to the amount of fluid retained in the system that could introduce smearing / hysteresis into the product.

I must confess that the words “smearing” and “hysteresis” in this context are new to me and I am assuming that in my language they mean something very similar to polluting.

I have revisited the design of the valve and come up with a configuration that greatly reduces the amount of liquid stored behind the valve.

Valve Mark 2.jpg
Valve Mark 2.jpg (52.76 KiB) Viewed 3072 times


This arrangement also does away with the overflow on the lower slant plate and the associated need to poke long screwdrivers down the column to bend the tab after soldering the plate.

Using the same theory and in the event that I win the lottery, I could always retro-fit a “proper valve” like this.

Valve Mark 2 b.jpg
Valve Mark 2 b.jpg (24.25 KiB) Viewed 3073 times



In all my reading I cannot remember seeing this particular set-up. I may have done, if so I will gladly give credit to the person who sowed the seeds in my mind. If not, why not? – is there something I am missing?

Any advice? / comments please.

Brian
(YHB)
Toodlepip
Brian

Why buy something you don't want,
When you can make something you do
.
User avatar
YHB
 
Posts: 114
Joined: Wed Oct 12, 2011 7:48 am
Equipment type: 2" LM / Pot / Proportional VM splitter with homemade needle valve and removable slant plates on 2.5 kW wooden boiler

Re: Reduction Of Smearing and Alternative to Boka Plate "Tab"

Postby Abussive » Mon Oct 24, 2011 8:00 am

Couldn't say if it's a "first", but I've not seen it that way before either.
The downside is the need to put another hole into the column. In my own (some unkind folk would say hamfisted....) handiwork, any holes or plates soldered into a column are prime candidates for exasperation when leaks are being tracked down.
I'll be pondering a lot on your suggestion...... the hysteresis I get from the Boka dams in my own still add significantly to the time it takes to "tune out" tails breakthrough. Not impossibly so, but I'd prefer to eliminate the problem as far as possible.

Nice post, great pics.
Adonis

Scientist, technocrat, 2nd-rate musician, improviser
m.o. :- "why buy it, if you can make it exactly as you want it"?
Mantra:- Measure twice, cut once. My short pencil is better than your long memory
User avatar
Abussive
 
Posts: 583
Joined: Tue Jun 07, 2011 7:23 am
Location: Middle England

Re: Reduction Of Smearing and Alternative to Boka Plate "Tab"

Postby minime » Mon Oct 24, 2011 9:56 am

I'm thinkin' you're gonna have vapor going up that reflux return line.........

It's probably not enough to hurt you but keep it in mind if things seem wonky.
User avatar
minime
 
Posts: 3971
Joined: Tue Dec 09, 2008 10:47 am
Location: Gr8WhiteNorth
Equipment type: VM enthusiast.

Re: Reduction Of Smearing and Alternative to Boka Plate "Tab"

Postby YHB » Mon Oct 24, 2011 10:12 am

That is a given, but what is the difference between vapour going between the plates to the condenser and vapour going up the "reflux return line" to the condenser?

You will have to be gentle with me I am still new to this technology.

If your concern is about vapour going up the stem of the valve, I have had a play stuffing the tube with spirally wound silicone sheet and it seems to make a good seal. Trying to blow through this "Gland" makes my eyes pop with no apparent leaks.


Brian
(YHB)
Toodlepip
Brian

Why buy something you don't want,
When you can make something you do
.
User avatar
YHB
 
Posts: 114
Joined: Wed Oct 12, 2011 7:48 am
Equipment type: 2" LM / Pot / Proportional VM splitter with homemade needle valve and removable slant plates on 2.5 kW wooden boiler

Re: Reduction Of Smearing and Alternative to Boka Plate "Tab"

Postby Abussive » Mon Oct 24, 2011 12:44 pm

Afterthought....
you do lose the "height equivalent" of the distance between the two horizontal tubes.

- you might be able to get away with a single (larger) hole, containing 2 pipes inside it. One is a drain from the Boka plate (liquid out to valve) and the other is a valve-out, returning liquid to the column centreline......? The pipe diameter must be able to cope with the maximim flowrate of falling liquid (not that much, even on a high-output still!)

Small is beuatiful, especially when it doesn't have to be big.
And it's cheaper.
:)
Adonis

Scientist, technocrat, 2nd-rate musician, improviser
m.o. :- "why buy it, if you can make it exactly as you want it"?
Mantra:- Measure twice, cut once. My short pencil is better than your long memory
User avatar
Abussive
 
Posts: 583
Joined: Tue Jun 07, 2011 7:23 am
Location: Middle England

Re: Reduction Of Smearing and Alternative to Boka Plate "Tab"

Postby Azframer » Mon Oct 24, 2011 1:35 pm

I think I see what you are trying to do. But instead of putting that tee in why not just above valve go straight in with soft copper. You could S bend it back to come back under tab and lower then valve. If you also put small up bend in it you would have slight pooling in it and close off the funky vapor looping minime might be thinking about.
Edit= 1/4" soft so it would drain off and not hold too much volume where you do create the pooling at end inside column.
Friends call me Rick
Drank all night and I am still thirsty!
But I don't feel like I got to much blood in my alcyhol.
User avatar
Azframer
 
Posts: 1168
Joined: Sat Oct 23, 2010 2:24 pm
Location: Navajo Rez, Arizona
Equipment type: 5 Gallon Pot Still, Dash1

Re: Reduction Of Smearing and Alternative to Boka Plate "Tab"

Postby YHB » Mon Oct 24, 2011 2:29 pm

Adonis wrote:Afterthought....
you do lose the "height equivalent" of the distance between the two horizontal tubes.

- you might be able to get away with a single (larger) hole, containing 2 pipes inside it. One is a drain from the Boka plate (liquid out to valve) and the other is a valve-out, returning liquid to the column centreline......? The pipe diameter must be able to cope with the maximim flowrate of falling liquid (not that much, even on a high-output still!)

Small is beuatiful, especially when it doesn't have to be big.
And it's cheaper.
:)
Adonis,



Thanks - I like it, you said - "Small is beuatiful, especially when it doesn't have to be big. And it's cheaper"

Small is not cheaper, 8mm fittings are ridicoulously expensive - 15mm fittings are cheap.

So, if we increase the loop to 15mm the only part that needs to be small is the vertical leg subject to pooling we can still make that 8mm or even 6mm.

By inspection I believe that the 15mm pipe and bends will be able to cope with the maximim flowrate of falling liquid whatever that may be - I have never seem a still pumping out 1/2" full bore.

Valve 3rd go.jpg
Valve 3rd go.jpg (23.95 KiB) Viewed 2968 times


Which leaves the loss of 1.1/2" of "height equivalent" being the distance between the two horizontal tubes. I am not too sure where this fits in. Is it the height equivalent of the column? - if so do I just make the Boka 1.1/2" taller? or what effect will the loss of 1.1/2" of "height equivalent" make.

The sketch is showing a standard valve, I will make one of my valves with 15mm fittings in a couple of days when I get back from my trip.


Azframer wrote:I think I see what you are trying to do. But instead of putting that tee in why not just above valve go straight in with soft copper. You could S bend it back to come back under tab and lower then valve. If you also put small up bend in it you would have slight pooling in it and close off the funky vapor looping minime might be thinking about.
Edit= 1/4" soft so it would drain off and not hold too much volume where you do create the pooling at end inside column.


Azframer Sorry - Rick,

Sorry mate I am having a bit of difficulty trying to imagine what you are suggesting. Any chance of a picture of some form - easiest way is to draw it with a pencil, and photograph it with your web cam and send like this
example.jpg
example.jpg (26.38 KiB) Viewed 2968 times


It only takes a minute and saves any confusion

Thanks mate

Brian (YHB)
Toodlepip
Brian

Why buy something you don't want,
When you can make something you do
.
User avatar
YHB
 
Posts: 114
Joined: Wed Oct 12, 2011 7:48 am
Equipment type: 2" LM / Pot / Proportional VM splitter with homemade needle valve and removable slant plates on 2.5 kW wooden boiler

Re: Reduction Of Smearing and Alternative to Boka Plate "Tab"

Postby Azframer » Mon Oct 24, 2011 2:49 pm

Just crude and over your drawing for quickness.
Edit= the hook inside column would not hold enough fluid to matter but just enough to keep vapor from going up in and through drain. and would stop most of pooling that the tee would allow.
Attachments
Valve 3rd go.jpg
Valve 3rd go.jpg (21.63 KiB) Viewed 2961 times
Friends call me Rick
Drank all night and I am still thirsty!
But I don't feel like I got to much blood in my alcyhol.
User avatar
Azframer
 
Posts: 1168
Joined: Sat Oct 23, 2010 2:24 pm
Location: Navajo Rez, Arizona
Equipment type: 5 Gallon Pot Still, Dash1

Re: Reduction Of Smearing and Alternative to Boka Plate "Tab"

Postby YHB » Mon Oct 24, 2011 3:30 pm

Rick,

Thanks for the clarification - I did not know you could mark up pictures - How did you do that?

The trouble about asking for advice is you get lots of different ideas sometimes conflicting.

A couple of initial thoughts with your suggestion

- the Hook will never drain unless you tip the column upside down
- I think that the fluid leaving the hook will tend to run back down the soft pipe to the walls of the column rather than into the center of the column

Additionally - I am trying to get my head around why vapour going up the take off line is a bad thing - Why would it be any different to vapours in a traditional Bok passing over the fluid in the slant plate dam? Can you shed any light on the subject?

Thanks for the input

Brian

- I am still trying to work out how to mark up pictures
Toodlepip
Brian

Why buy something you don't want,
When you can make something you do
.
User avatar
YHB
 
Posts: 114
Joined: Wed Oct 12, 2011 7:48 am
Equipment type: 2" LM / Pot / Proportional VM splitter with homemade needle valve and removable slant plates on 2.5 kW wooden boiler

Re: Reduction Of Smearing and Alternative to Boka Plate "Tab"

Postby Azframer » Mon Oct 24, 2011 4:33 pm

1st off I just right clicked and opened it in paint and just made a quick swipe.
2nd I don't run a Bok so it is not in my running but made suggestion due to minime's concerns of the vapor going up that route.
3rd the hook was a bit extreme and was not meant to be so large and with what I am thinking would need to be only shallow hook to keep the vapor traveling up. slight tilt should empty out.
4th trying to get hook to be at center line of column by paint on a ball mouse is harder than it looks. :roflmao:
It is only a suggestion to ponder and let those with more time in running a Bok to give you the thumbs up or down.
Friends call me Rick
Drank all night and I am still thirsty!
But I don't feel like I got to much blood in my alcyhol.
User avatar
Azframer
 
Posts: 1168
Joined: Sat Oct 23, 2010 2:24 pm
Location: Navajo Rez, Arizona
Equipment type: 5 Gallon Pot Still, Dash1

Re: Reduction Of Smearing and Alternative to Boka Plate "Tab"

Postby Tracker » Mon Oct 24, 2011 4:59 pm

Some great thinking here Brian and in my opinion a more improved version of your initial idea. It should give much clearer defined change-over points.
I am with you in that I do not believe that vapour and liquid in the pipe work is a huge problem (so long as their is sufficient room for both vapour and liquid in the pipe) but then Mini was only mentioning that fact in case it does become an issue later on.

Cheers
User avatar
Tracker
 
Posts: 1550
Joined: Mon Dec 22, 2008 10:05 pm
Location: The Land down under
Equipment type: 50 litre keg, SD 2" to 4" torpedo with 2 bubble plates, Dephlegmator, Pot still arm, copper SPP and condenser.(Tracker Stacker Flavour Packer)
Various pot still/thumper configurations.
Bok 2" slant plate for neutral and cleaning up mistakes.

Re: Reduction Of Smearing and Alternative to Boka Plate "Tab"

Postby Rise-N-Shine » Mon Oct 24, 2011 6:44 pm

i like the idea. i think ill modify my slant plate set up this way.

i dont think that vapors migrating would be a big deal but a bologna cut on that tube will reduce it . there wont be a leading edge for the vapors to catch
Attachments
1.jpg
1.jpg (39.94 KiB) Viewed 2923 times
User avatar
Rise-N-Shine
 
Posts: 239
Joined: Mon Feb 01, 2010 5:38 pm
Location: NorthEast USA
Equipment type: 15.5 Keg 2" packed column. crossflow , leibig and offset head condensers
propane fired

Re: Reduction Of Smearing and Alternative to Boka Plate "Tab"

Postby Azframer » Tue Oct 25, 2011 3:31 pm

Rise-N-Shine :doh: :8)
Friends call me Rick
Drank all night and I am still thirsty!
But I don't feel like I got to much blood in my alcyhol.
User avatar
Azframer
 
Posts: 1168
Joined: Sat Oct 23, 2010 2:24 pm
Location: Navajo Rez, Arizona
Equipment type: 5 Gallon Pot Still, Dash1

Re: Reduction Of Smearing and Alternative to Boka Plate "Tab"

Postby crozdog » Wed Oct 26, 2011 12:31 am

The big issue I see with this design (apart from having to drill more holes & buy more fittings) is the size of the pipe.

My old Bok uses 100mm of 1/4" to the needle valve. lets say that the 6.4mm diameter OD pipe has 1.2mm thick walls this leaves a 4mm ID which will hold around 12ml of liquid

compare that to the 1/2" pipe in the design. assuming the ID is 12.6mm, a 100mm length of pipe will hold around 125ml (if you're no good with maths try http://www.handymath.com/cgi-bin/cylinder.cgi)

That is TEN TIMES the volume! Does that show you where / how smearing may be occurring?

So my suggestions are to simply reduce your pipe size (both length & diameter) as well as use a straight output to a valve & forget about the return from the valve as liquid that can't pass the valve will cause flow to "back up" up the pipe onto the plate & overflow from there - and that is one of the things that makes the BOK LM still such a beautiful thing!

Remember the KISS principle :beer:
crozdog
 
Posts: 134
Joined: Thu Apr 15, 2010 7:05 pm
Location: lost in oz
Equipment type: 2" Bok
2" VM
2" pot
all fit on a 55l electric laundry "copper"

Re: Reduction Of Smearing and Alternative to Boka Plate "Tab"

Postby Tracker » Wed Oct 26, 2011 1:47 am

crozdog, chech the first picture of the thread. The pipe size where ponding will occur is 3/8" and by the looks of the scale it would be lucky if it were 3/4" long. The capacity there is not great.


Cheers.
User avatar
Tracker
 
Posts: 1550
Joined: Mon Dec 22, 2008 10:05 pm
Location: The Land down under
Equipment type: 50 litre keg, SD 2" to 4" torpedo with 2 bubble plates, Dephlegmator, Pot still arm, copper SPP and condenser.(Tracker Stacker Flavour Packer)
Various pot still/thumper configurations.
Bok 2" slant plate for neutral and cleaning up mistakes.

Next

Return to Packed Columns

Who is online

Users browsing this forum: No registered users and 3 guests