3"VM / 3"Bokmini showdown

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3"VM / 3"Bokmini showdown

Postby minime » Mon Oct 20, 2008 2:18 am

Let me preface by saying that I had no intention of comparing the output rate of these two columns. I put the 3" Bok mini together because I had the pipe and I had a large batch of Pugirum recipe to still and didn't want a marathon on the 2" offset. Both columns are the same length but the Bok has only 6 scrubbers in it.

Image

As it turns out and I didn't expect this:
Both columns have nearly identical output rates. Some time ago while working on the VM column I got a PM from Riku indicating I was at the limit for pure product on 3" column by calculating vapor speed in the column. That theory is apparently correct because I was not able to collect at 95.6% when I increased the takeoff rate past the gallon an hour on the Bok.

The VM column will not exceed one gallon per hour. When I add more heat the reflux ratio increases but output remains stable. The VM column I built is in this thread viewtopic.php?f=17&t=7647
The Bok because it's condensing all the vapor can be driven to higher output rates but I found an immediate decrease in quality as soon as the takeoff rate went over the gallon per hour. It was really uncanny. I suspect the Bok might squeeze a little more if the column had been fully packed but I did not want to do that as I was 'stilling white rum.

So now having experience with both VM and LM columns of the same size and length my conclusion.

For ease of operation the VM column wins hands down. It's nearly impossible to make a mistake with that column. On my last run after heads had been removed I opened the ball valve wide open and collected for just over two hours, one gallon per hour of pure 95.6. On the first indication of temperature increase I closed the valve down to reduce output and collected 3 quarts of 95.6 over the next two hours. At that point the still had slowed to a drop per second and I shut down.

The Bok was rock solid stable for two hours as I collected the first two gallons. Although it wasn't difficult the takeoff rate required several adjustments through the next two hours to keep it at 95.6% with max output. I was able to collect another 2.5 quarts in that two hours. It certainly was not difficult but not nearly as easy as the VM column. In my opinion the VM build is a bit easier with off the shelf parts. The Bok requires a bit of skill in layout and patience in cutting and soldering the still head but the design is definitely elegant and perfectly balanced. The cooling liebig only needs to be very tiny also a plus.

Either design will get you a great product. If you need to drive the still to lower than 95.6 you'd be better with the Bok.
Hope this helps some of you folks trying to decide which way to go...............
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Re: 3"VM / 3"Bokmini showdown

Postby tracker0945 » Mon Oct 20, 2008 4:34 am

Great reporting.

Good to see the side by side results.

Cheers.
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Re: 3"VM / 3"Bokmini showdown

Postby ZAXBYC » Mon Oct 20, 2008 5:58 am

:shock: Jealous!

Nice Work :)
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I use the head part of this unit for stripping and as a Pot Still- produces LOTS of flavour :D
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Re: 3"VM / 3"Bokmini showdown

Postby rad14701 » Mon Oct 20, 2008 6:10 am

Nice comparison, minime... It might be worth noting in your original post that it is the VM is on the left and the Bokakob is on the right in your picture...
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Re: 3"VM / 3"Bokmini showdown

Postby theholymackerel » Mon Oct 20, 2008 6:45 am

minime wrote: Both columns are the same length but the Bok has only 6 scrubbers in it.....
I suspect the Bok might squeeze a little more if the column had been fully packed but I did not want to do that as I was 'stilling white rum.


The 3 inch inline eliptical wasn't runnin' anywhere near optimum efficiency with such little packin'. Not really a fair compairison against an optimised VM column.

Fully pack the column on that inline eliptical and it'll be much more efficient.
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Re: 3"VM / 3"Bokmini showdown

Postby Master-Peter » Mon Oct 20, 2008 7:24 am

:P Outstanding report :P
Thanks Minime :mrgreen:
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Re: 3"VM / 3"Bokmini showdown

Postby minime » Mon Oct 20, 2008 7:31 am

theholymackerel wrote:
minime wrote: Both columns are the same length but the Bok has only 6 scrubbers in it.....
I suspect the Bok might squeeze a little more if the column had been fully packed but I did not want to do that as I was 'stilling white rum.


The 3 inch inline eliptical wasn't runnin' anywhere near optimum efficiency with such little packin'. Not really a fair compairison against an optimised VM column.

Fully pack the column on that inline eliptical and it'll be much more efficient.


Right, I used 1.75 oz scrubbers so 15 to 18" was the packing length.
I gotta wonder how much more you could bleed with full packing. If I'm still curious in the spring I'll give it a go. I've wrapped up operations for this year as we've already had some heavy nite time frost and snow is 'bout to follow. I believe there's a little more efficiency to squeeze out of the VM column also and Hookline might be toying with that sometime in the near future. I attained my original goal of getting a full spirit run done in under 8 hours so I'm thrilled to say the least.
All in all it's been lots of fun.

Edit for this remark.
When stripping I'm getting about 2 gallons per hour so if I'm collecting 1 gallon per hour on the spirit run that's a one to one reflux ratio. One gallon removed for every 2 gallons vaporized. How low can you go on the reflux ratio before quality goes out the window with a 5 foot column? Comments please.
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Re: 3"VM / 3"Bokmini showdown

Postby theholymackerel » Mon Oct 20, 2008 11:19 am

minime wrote: I gotta wonder how much more you could bleed with full packing. If I'm still curious in the spring I'll give it a go.


I hope ya do test it in the spring. I'd like to know, and I bet others would too.
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Re: 3"VM / 3"Bokmini showdown

Postby rad14701 » Mon Oct 20, 2008 3:58 pm

minime wrote:When stripping I'm getting about 2 gallons per hour so if I'm collecting 1 gallon per hour on the spirit run that's a one to one reflux ratio. One gallon removed for every 2 gallons vaporized. How low can you go on the reflux ratio before quality goes out the window with a 5 foot column?

Only tasting and alcometer readings will yield the answer you are seeking... Every still will react differently, even when it comes to reflux ratios affecting overall output quality...

From what I've experienced it seems that a ratio of 2:1 to 4:1 is the best range... Below 2:1 starts getting iffy, similar to a stripping run, and for most purposes anything above 4:1 just wastes more time than the improved results justify...
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Re: 3"VM / 3"Bokmini showdown

Postby minime » Fri Oct 24, 2008 12:56 am

theholymackerel wrote:
I hope ya do test it in the spring. I'd like to know, and I bet others would too.



Ok, Ok, Ok..........I started two 60 liter sugar washes yesterday. :lol: Guess you folks have figured out by now I hate unanswered questions and besides I had most of the sugar. I also had 3 packs of Alcotec Vodka Star turbo yeast which I didn't like. (too slow) so I pitched it all into one 60 liter ferment and the other ferment I used bulk bakers yeast, dap, and lemon juice. I threw in the aquarium heaters and they're bubblin' away. Both ferments have 14KG of sugar for 14% potential. I know the turbo will work right down to .990 but I'm wondering 'bout the bakers yeast. I expect these ferments to go a little slow because the heaters only work at the top of the wash and the bottom is quite cool.

I'll finish packing the column with stainless and I'll push the Bok to see what it can produce. I'm hoping there's not much difference 'cause I really like the way the VM column runs but I will be impartial.

Stay tuned, this should be all wrapped up within a couple of weeks.
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Re: 3"VM / 3"Bokmini showdown

Postby ZAXBYC » Fri Oct 24, 2008 3:52 am

Stay tuned, this should be all wrapped up within a couple of weeks.


I am eagerly awaiting the results :) I will have a lot of 2"/54mm pipe left over from my build this weekend so will probably make a VM at some point in the future. :mrgreen:
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Re: 3"VM / 3"Bokmini showdown

Postby rad14701 » Fri Oct 24, 2008 4:57 am

Admit it, minime, you were already suffering from fermentation/distillation withdrawls... :twisted:
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Re: 3"VM / 3"Bokmini showdown

Postby minime » Fri Oct 24, 2008 7:40 am

rad14701 wrote:Admit it, minime, you were already suffering from fermentation/distillation withdrawls... :twisted:



LOL, I gotta admit it was kinda strange steppin' into the garage with no yeast smell out there. It's been a couple of years since there wasn't something going 'cept for a brief period last winter when I was getting ready to move. I stilled in the basement at the other house and never could get far enough ahead to take the winter off so there was always something fermenting.

I forgot that bread yeast is a top fermenter so I had a bit of a mess to clean up this morning. The turbo sank and went right to work. There's still a lot of top activity on the bread yeast. I don't want to cross contaminate these ferments with the hydrometer so I'll wait until one of em slows way down before I start looking at final sg. I'm thinking the bread yeast being a top fermenter and the aquarium heater keeping the top warmer should finish first. The Vodka star yeast says a 5 day ferment on the packet. That's why I don't like it.
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Re: 3"VM / 3"Bokmini showdown

Postby minime » Tue Oct 28, 2008 9:37 am

minime wrote:Ok, Ok, Ok..........I started two 60 liter sugar washes yesterday. :lol: Guess you folks have figured out by now I hate unanswered questions and besides I had most of the sugar. I also had 3 packs of Alcotec Vodka Star turbo yeast which I didn't like. (too slow) so I pitched it all into one 60 liter ferment and the other ferment I used bulk bakers yeast, dap, and lemon juice. I threw in the aquarium heaters and they're bubblin' away. Both ferments have 14KG of sugar for 14% potential. I know the turbo will work right down to .990 but I'm wondering 'bout the bakers yeast. I expect these ferments to go a little slow because the heaters only work at the top of the wash and the bottom is quite cool.


This post is to address the yeast question posted above. The turbo with the extra yeast pack finished in 48 hours flat. I was taken by surprise as it didn't seem to be working very hard at all. The bread yeast just could not get any traction and was looking like a two week ferment so I dipped about 3 gallons from the turbo wash into it and it finished in 4 days. I stripped both washes and the spirit run is in the last part of heads removal as I type this so we'll have a good answer within a couple of hours.

stay tuned
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3"VM / 3"Bokmini showdown Conclusion

Postby minime » Tue Oct 28, 2008 11:28 am

After heads were gone it took about 10 minutes to find the sweet spot on the fully packed Bok. It looked pretty impressive and I was a little concerned there'd have to be some more optimization work done on my VM column but it ain't so. Running the Bok right at the cusp of temperature runaway it put out maybe 200 ml more than a gallon in the first hour and that's a generous guestimate as it wasn't worth measuring.

Certainly is not worth mentioning and as stated before I love the way the VM column operates. It's wide open on the valve after heads are gone and one good adjustment to reduce output at the onset of temperature increase and that takes me right through the end of the run. There is no compelling reason to do any more work on the VM design I've used. Again thanks to all who contributed and thanks to Riku and Hookline for inspiring me down this path.

There's a couple of you out there that are currently building the same column and I can honestly say, it is hands down the best tool for the job.

So there you have it folks I can put my mind to rest :mrgreen:
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Re: 3"VM / 3"Bokmini showdown

Postby punkin » Tue Oct 28, 2008 11:32 am

Nice work mate.



On assumes there'll be a classified ad for a bok4sale inserted shortly? :mrgreen:
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Re: 3"VM / 3"Bokmini showdown

Postby HookLine » Tue Oct 28, 2008 12:01 pm

minime wrote:So there you have it folks I can put my mind to rest.


Nah, betcha you can't resist coming up with more of your damn crazy ideas over that long winter. :wink:

But seriously. Excellent set of experiments you have done on VM columns, including comparing them to the Bok slanted plate. A substantial advance for our little hobby.

Loud applause for Mr Minime.

(Glad I chose a VM for my first column. 8) )
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Re: 3"VM / 3"Bokmini showdown

Postby minime » Tue Oct 28, 2008 12:53 pm

HookLine wrote:(Glad I chose a VM for my first column. 8) )


Absolutely the coolest way to run neutrals :D

@punkin
One assumes there'll be a classified ad for a bok4sale inserted shortly?

Nope, I gonna chop a good chunk off the bottom, remove most of the packing and use it exclusively for white rum and removing heads on flavored drinks.
Don't want to get my perfectly neutral vodka column contaminated with that pirate swill :wink:
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Re: 3"VM / 3"Bokmini showdown

Postby rad14701 » Tue Oct 28, 2008 1:48 pm

Sounds like you've got the VM tuned in good there, minime... So, are you still running it with the 2 X 1 reducer in the column as mentioned in your build thread...??? I also recall your concern regarding reducer assembly inside the column... If the performance is as good as you've proven, it might be well worthwhile to whip up CAD drawings and build instructions... After all, you are looking for something to do during the cooler weather... 8)
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Re: 3"VM / 3"Bokmini showdown

Postby minime » Tue Oct 28, 2008 3:14 pm

rad14701 wrote:Sounds like you've got the VM tuned in good there, minime... So, are you still running it with the 2 X 1 reducer in the column as mentioned in your build thread...??? I also recall your concern regarding reducer assembly inside the column... I

Here's the photo of the head design............wish I knew how to do cad drawings.
Edit for this remark. this photo is taken viewing the bottom of the head. Vapor stream would be split to flow to product condenser and reflux condenser.
Image

I'm determined to learn how to pot still this winter wtih some small ferments and much smaller pot. 25 quart as opposed ot 75 quart. I could put together some pencil drawings on graph paper if anyone's interested. I think it would be an easier build with a 3X2 tee and a 2 inch street elbow inside. All the soldering could then be done from the outside of the tee. No matter how it's accomplished it's worth the effort.
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Re: 3"VM / 3"Bokmini showdown

Postby rad14701 » Wed Oct 29, 2008 12:29 pm

At minime's request I am posting two versions of the head for his VM column based on his description of possible modifications to his original design... I have been playing with A9CAD Free Version which doesn't have all of the features I'd like but it worked for these crude images...

Based on proposed modifications to the original design...

Image


A modified version with reduction taking place later in the vapor path...

Image
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Re: 3"VM / 3"Bokmini showdown

Postby absinthoman » Fri Oct 31, 2008 11:28 am

What about using a slanted plate in the big T. In my design I wanna use a 2'' column and a 2''/2''/1'' T for the head and try to put a slanted plate just above the 1'' joint. That's gonna have pretty much the same effect of driving the vapour towards the gate valve . What you think?
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Re: 3"VM / 3"Bokmini showdown

Postby minime » Fri Oct 31, 2008 11:50 am

absinthoman wrote:What about using a slanted plate in the big T. In my design I wanna use a 2'' column and a 2''/2''/1'' T for the head and try to put a slanted plate just above the 1'' joint. That's gonna have pretty much the same effect of driving the vapour towards the gate valve . What you think?


That might very well work but in this thread viewtopic.php?f=17&t=7647 there is some discussion regarding the distribution of reflux. I would think it would depend on the ratio of open column to your plate that is capturing and directing the vapor. I think if I were going to try that I'd likely leave about 1/3 of the column open. If that proves to be too little reflux or the reflux is channeling you could always drill some holes in the plate. Might be a simpler way of accomplishing the same thing.
Good luck and let us know how it goes :)
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Re: 3"VM / 3"Bokmini showdown

Postby rad14701 » Fri Oct 31, 2008 1:58 pm

Actually, the amount of unobstructed area in minime's 3x3x2 is approximately 56% when you consider the area of the 3 inch being 7.07 squate inches and the 2x1 reducer being 3.14 square inches... 1-(3.14/7.07=.44)=.56 or 56% free space... So that means what...??? It means that blocking more than 50% is gonna toss a whole lot more vapor into the take-off than minime's current 44%... I'd probably start by cutting in for a slant plate to the halfway point at about a 30 degree slope towards the center of the column, starting at the top of the Tee... You could always de-solder, cut deeper, and solder in a new slant plate if you decide you need for vapor deflection... Just my two cents...
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Re: 3"VM / 3"Bokmini showdown

Postby minime » Sat Nov 01, 2008 7:05 am

rad14701 wrote:Actually, the amount of unobstructed area in minime's 3x3x2 is approximately 56% when you consider the area of the 3 inch being 7.07 squate inches and the 2x1 reducer being 3.14 square inches... 1-(3.14/7.07=.44)=.56 or 56% free space... So that means what...??? It means that blocking more than 50% is gonna toss a whole lot more vapor into the take-off than minime's current 44%... I'd probably start by cutting in for a slant plate to the halfway point at about a 30 degree slope towards the center of the column, starting at the top of the Tee... You could always de-solder, cut deeper, and solder in a new slant plate if you decide you need for vapor deflection... Just my two cents...


Hmm, this idea has me intrigued. I'm looking at the Bok head and thinking about turning it upside down.



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Re: 3"VM / 3"Bokmini showdown

Postby punkin » Sat Nov 01, 2008 10:35 am

Light the heater and run it on neutral.

We need to know the ultimate design. I have to build one for a mate now after giving him a sample of my first neutral.
He's been brewing 'neutral alchohol' for years with an internal reflux and turbos, now after a few tastes he's converted.












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Re: 3"VM / 3"Bokmini showdown

Postby minime » Sat Nov 01, 2008 12:02 pm

punkin wrote:Light the heater and run it on neutral.
We need to know the ultimate design. I have to build one for a mate now after giving him a sample of my first neutral.
He's been brewing 'neutral alchohol' for years with an internal reflux and turbos, now after a few tastes he's converted.
I'llDoHisWeaponInThreeInchPunkin

LOL.......In fact I intend on giving this idea a go but I've run myself right out of supplies. Just yesterday I was offered 6 feet of 4" copper for the princely sum of 2 gallons of 95.6 white rum. I don't think I'll ever get another chance at 4" copper and I don't have the rum to spare so here we go again. I've ordered supplies and hopefully I'll have a shiny chunk of 4" copper by the end of November. (don't think I'll ever use it but you never know :mrgreen: )
In the meantime I'm going to convert the Bok to the new configuration and shorten it up to 40".

Punkin, your column could quite easily be converted immediately if you're up for it. Probably wouldn't take more than an hour to slip a plate in there. Wouldn't do any good though if you've nothing to run.

Thanks to Absinthoman for this idea BTW
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Re: 3"VM / 3"Bokmini showdown

Postby HookLine » Sat Nov 01, 2008 1:37 pm

minime wrote:Just yesterday I was offered 6 feet of 4" copper for the princely sum of 2 gallons of 95.6 white rum. I don't think I'll ever get another chance at 4" copper and I don't have the rum to spare so here we go again. I've ordered supplies and hopefully I'll have a shiny chunk of 4" copper by the end of November. (don't think I'll ever use it but you never know :mrgreen: ) In the meantime I'm going to convert the Bok to the new configuration and shorten it up to 40".

[snip]

Thanks to Absinthoman for this idea BTW


Told you that you wouldn't be able to resist trying more stuff. You didn't even last a week! :roll: :wink: :mrgreen:

Or to put it another way:

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Re: 3"VM / 3"Bokmini showdown

Postby minime » Sat Dec 06, 2008 4:54 pm

The balance of this thread was moved here viewtopic.php?f=17&t=8828 as it strayed far from the original intent of the post.

Thanks for the help on this Tater
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Re: 3"VM / 3"Bokmini showdown

Postby diesel4ever » Wed Jun 23, 2010 11:41 pm

The internal downward turned elbow design will help with condensate distribution in your packing as well which will increase efficiency of your column. I did this with my CM still I built so condensate flows down rather than one small stream in the middle but throughout the packing at any reflux ratio. Brilliant!
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