LM at the extremes

[rgreen2002]

So I've been searching HD google and I can't seem to come up with any answers. I'm once again hoping you fine folks can help me a little here.

I'm running a 2" Bok and I've really been enjoying the recent batch of flute builds. They are quite beautiful and versatile,,,and fast... So I've been wondering.. how could I push the Bok so that I could get good results (lets say produce a GNS) with one run? I strip run everything in my pot now and then spirit run through the Bok. Could I eliminate the strip and still get a good product. The Bok creates a stacked column via structured packing and I understand that the column is not very stable which I would think is the limiting factor...?

The other extreme I can't quite grasp either. I have seen a few folks say you can run your Bok from 0-100%, suggesting that you can dial up or down the ABV produced. I cannot find the "How" part of that statement and I'm curious as to How? I know the Bok is designed for a GNS and if I wanted less I could build something else but I would like to grasp the concept before moving on...

[shadylane]

I'm not a boka jocky, but here's my thought's
It's a LM still. Increase the take off and the reflux along with the ABV decreases

[Monkeyman88]

What he said. I run a 2" boka and can do it all. Strip as a pot still with the take off wide open and spirit run whiskey and rum like that. Or close the valve back up and take off at anywhere up to 95%.

[rgreen2002]

I'm not a boka jocky, but here's my thought's
It's a LM still. Increase the take off and the reflux along with the ABV decreases

What he said. I run a 2" boka and can do it all. Strip as a pot still with the take off wide open and spirit run whiskey and rum like that. Or close the valve back up and take off at anywhere up to 95%.

Thanks gents... Opening the valve too much would destabilize the column and then allow smearing? Really just trying to put the last pieces of the LM together in my brain.

[Monkeyman88]

Yes. Just like a pot still.

[Monkeyman88]

I open it all the way. Full lock open to run as a pot still so there is no reflux. Slowly closing the valve lets more and more reflux happen. Raising the proof.

[bearriver]

GNS is a low place to set the bar IMO. You can and should do better.

I'm not sure exactly what the question is... If you want neutral then a LM design is a fine choice. I get 1 gallon of azeotrope per hour from a 3" LM packed with lava rock. YMMV

[drmiller100]

. I get 1 gallon of azeotrope per hour from a 3" LM packed with lava rock. YMMV

how many watts/btus??
how tall is the packing in your column?

Thanks!

[bearriver]

I'm not a boka jocky, but here's my thought's
It's a LM still. Increase the take off and the reflux along with the ABV decreases

+1. Do this until you are not happy with the results. Faster vapor velocities will decrease the proof and contribute to smearing the fractions. This can be a good or bad depending on what you are trying to accomplish.

I run at equilibrium after my heads cut, and adjust the power to a controlled flood (max power threshold prior flooding conditions). Essentially I am keeping a small bed of fluid on top of the packing for the vapor to diffuse through and make a phase change. Then I add takeoff and more heat to compensate for the lost reflux. The idea in my mind is to keep that bed stable during this transition. Practiced hands make quick work of it.

If you want easy then get a sight glass on top of the packing. I learned without and can say that's a pain in the butt.

. I get 1 gallon of azeotrope per hour from a 3" LM packed with lava rock. YMMV

how many watts/btus??
how tall is the packing in your column?

Thanks!

4800-5500 watts depending on the ABV of the wash. 1.2 meters of packing. The lava rock is sorted for porosity and classified to half inch minus.

[drmiller100]

If you want easy then get a sight glass on top of the packing. I learned without and can say that's a pain in the butt.

The lava rock is sorted for porosity and classified to half inch minus.

Rather than a sight glass, I went down 10 percent in my column from the top, and stuffed in a digital temp gauge. The temp should be slightly higher than the condenser temp.

Then I adjusted the still based on that 10 percent number. This gave me "margin". Same basic result.

I never had a sight glass. I always figured the column would flood at the bottom first - water is less viscous than alcohol.

FWIW, I ABSOLUTELY respect your 1/2 minus grading of lava rocks. My conclusion was marbles were better than lava rocks as they were more consistent, but there is not much difference if you are careful with choice of rocks being relatively round and consistently shaped.

also, FWIW, I ended up at 4800 watts for a 3 inch column which is RIGHT at the ragged edge of flooding in my setup....

Thank you very much for the information!

[rgreen2002]

GNS is a low place to set the bar IMO. You can and should do better.

I'm not sure exactly what the question is... If you want neutral then a LM design is a fine choice. I get 1 gallon of azeotrope per hour from a 3" LM packed with lava rock. YMMV

LOL..sorry Bear, thread was kinda falling away there. I had two questions... 1. Can I eliminate the strip run before my Bok with good results, 2. How can I get anything but a neutral with a boka. Kinda the extremes. I'm indirectly also solidifying my understanding of the LM. The whole thread makes good sense to me.

Question 2: If I DO understand it then if i were looking for a product that was not a GNS ( and hopefully with more flavor) I would open the takeoff more which decreases reflux. This would allow for smearing of the fractions... a little can be good, a lot probably not so much. That's the balance if I have the concept right.

I've run it detuned as a pot still as well so I get that.

I'm also still crushing lava rock in the basement...

Question 1: On the other end of the spectrum, could I reflux enough as to not "need" my stripping run? I feel like this answer is "yes, but" as in yes but it would take forever and I would constantly be opening and closing the takeoff to reflux (this is all in theory). Intellectually I'm just separating the action in the LM with the flute (both column stills... trying to see similarities and differences for my own understanding)

If you want easy then get a sight glass on top of the packing. I learned without and can say that's a pain in the butt.

Funny you should mention:

Sight

sight glass.jpg (24.47 KiB) Viewed 3661 times

this is coming tuesday. I read a few threads a few weeks back and the vids were very helpful to understand the fluid bed and flooding concepts. It seemed that this would be helpful to understand the column as well as know when tails were coming up... and look nice.

Yes. Just like a pot still.

MM - Thanks. the pot still analogy makes good sense to me as well. Appreciated

[FreeMountainHermit]

GNS ?
-----,.. neutral spirit

[Monkeyman88]

GNS ?
-----,.. neutral spirit

Grain neutral spirit.

[Monkeyman88]

GNS is a low place to set the bar IMO. You can and should do better.

I'm not sure exactly what the question is... If you want neutral then a LM design is a fine choice. I get 1 gallon of azeotrope per hour from a 3" LM packed with lava rock. YMMV

LOL..sorry Bear, thread was kinda falling away there. I had two questions... 1. Can I eliminate the strip run before my Bok with good results, 2. How can I get anything but a neutral with a boka. Kinda the extremes. I'm indirectly also solidifying my understanding of the LM. The whole thread makes good sense to me.

Question 2: If I DO understand it then if i were looking for a product that was not a GNS ( and hopefully with more flavor) I would open the takeoff more which decreases reflux. This would allow for smearing of the fractions... a little can be good, a lot probably not so much. That's the balance if I have the concept right.

I've run it detuned as a pot still as well so I get that.

I'm also still crushing lava rock in the basement...

Question 1: On the other end of the spectrum, could I reflux enough as to not "need" my stripping run? I feel like this answer is "yes, but" as in yes but it would take forever and I would constantly be opening and closing the takeoff to reflux (this is all in theory). Intellectually I'm just separating the action in the LM with the flute (both column stills... trying to see similarities and differences for my own understanding)

If you want easy then get a sight glass on top of the packing. I learned without and can say that's a pain in the butt.

Funny you should mention:

sight glass.jpg

this is coming tuesday. I read a few threads a few weeks back and the vids were very helpful to understand the fluid bed and flooding concepts. It seemed that this would be helpful to understand the column as well as know when tails were coming up... and look nice.

Yes. Just like a pot still.

MM - Thanks. the pot still analogy makes good sense to me as well. Appreciated

When refluxing, you don't open close, open close the valve. Close it to equalise the column and stack the fraction, then slowly crack the valve. Open it just enough to get some drips, then adjust from there to the rate/ABV you want.
For example, when I do a stripping run, I let the column stack for ~10 mins, then open the valve about 1/16 of a turn to get the fores/heads out at a few drips per second for ~150ml. Then I open the valve full open, about 3 turns, and collect about 10L off a 40L charge. If I'm doing a spirit run, I do the same thing for the heads, and then depending on what I'm making, either flavoured or vodka, I either open the valve right up again, or open it about 1/2 to 3/4 of a turn to get a nice flow of 93%.

[rad14701]

I honestly don't think a 2" Bokakob dual slant plate column is going to produce enough spirits at a high enough proof to the OP's satisfaction in a single pass... At least not without substantial modification... Fast strips and then a fast spirit run is how most members are running... Now, that being said, I can collect ~1/2 gallon per hour from my 1.25" LM reflux column with low wines or fresh wash using marbles... The rig has a ~22:1 height:diameter packed column ratio...

High output at azeotrope requires a high height:diameter ratio and ample structured packing voidage to avoid total column flooding... At high output rates the flooding starts at the top of the column, not the bottom, due to boiler pressure buildup... This is the most dangerous form of flooding because you end up with ~95% alcohol shooting out the top of your column... I have not been able to induce total flooding to date with marbles...

All that being said, I still do fast stripping runs followed by a fast spirit run because fast spirit runs using wash requires a lot more attention and adjustment throughout the run...

We have to live within the capabilities of our equipment... If you want a one run and done at a decent output rate you need to upgrade to a plated column... Otherwise, stripping followed by spirit run is the best option...

[Danespirit]

+1 Rad
The time spend on a strippingrun, would easily be compensated for at the end of the day.
Regardless if i run my VM or LM, i always do a fast strippingrun on my potstill.
I draw the foreshots by the drip and then crank up the power, collecting all the way down to 20% ABV.
To give you a idea of how fast i run, you can watch the video of a strippingrun here: http://1drv.ms/1F4TEAa" onclick="window.open(this.href);return false;" rel="nofollow

[Monkeyman88]

Nice speed there DS. I get about the same rate, maybe a little faster when I strip using my keg still.

To the OP: having done both strip and spirit runs, and single runs. If timed that it actually takes less time, to strip and then re run than it does to single run if I want vodka.
Takes 7+ hours to single run to 94-95%. Or I can do a strip, collecting down to 20% in 2 1/2- 3 hours. And then spirit run at 93-94% in about 3 hours.

[rgreen2002]

Thanks everyone. I posed the question to understand the LM at its extremes. This allows me to mentally understand "between the extremes" (it's normal function).

When refluxing, you don't open close, open close the valve. Close it to equalise the column and stack the fraction, then slowly crack the valve. Open it just enough to get some drips, then adjust from there to the rate/ABV you want.
For example, when I do a stripping run, I let the column stack for ~10 mins, then open the valve about 1/16 of a turn to get the fores/heads out at a few drips per second for ~150ml. Then I open the valve full open, about 3 turns, and collect about 10L off a 40L charge. If I'm doing a spirit run, I do the same thing for the heads, and then depending on what I'm making, either flavoured or vodka, I either open the valve right up again, or open it about 1/2 to 3/4 of a turn to get a nice flow of 93%.

MM - thanks. This is how i perceive I could get GNS without a strip...theoretically only. It would represent one of the extremes I'm trying to picture. For the Bok I normally (after fores/heads) equilibrate and then open to collet at a relatively steady rate.

I honestly don't think a 2" Bokakob dual slant plate column is going to produce enough spirits at a high enough proof to the OP's satisfaction in a single pass... At least not without substantial modification... Fast strips and then a fast spirit run is how most members are running... Now, that being said, I can collect ~1/2 gallon per hour from my 1.25" LM reflux column with low wines or fresh wash using marbles... The rig has a ~22:1 height:diameter packed column ratio...

High output at azeotrope requires a high height:diameter ratio and ample structured packing voidage to avoid total column flooding... At high output rates the flooding starts at the top of the column, not the bottom, due to boiler pressure buildup... This is the most dangerous form of flooding because you end up with ~95% alcohol shooting out the top of your column... I have not been able to induce total flooding to date with marbles...

All that being said, I still do fast stripping runs followed by a fast spirit run because fast spirit runs using wash requires a lot more attention and adjustment throughout the run...

We have to live within the capabilities of our equipment... If you want a one run and done at a decent output rate you need to upgrade to a plated column... Otherwise, stripping followed by spirit run is the best option...

Thanks rad... Agreed. I really do not believe it is possible to do without a strip and currently I do so now. I think what I was trying to differentiate the LM column from the flute column. Here is what I'm thinking (where I get into most trouble) - both are column/fractionating stills, both rely on HETP/reflux ratio for product formation/purity. The flute plates are actual plates where the bok "plates" are theoretical spots in the column... If the bok column would never become unstable, could it be the same as the flute. From my reading here... (I have no BTDT experience with the flute...) you can basically throw wash/mash at it and in one run get a finished product.

Right now I'm happy with the Bok and I wan't to have a good understanding of it. I don't plan on skipping the strip run anytime soon. I've gone as high as 97% ABV and I usually run it between 92-95% and am happy. I will try running a little lower soon to see how much flavor I can bring across.

+1 Rad
The time spend on a strippingrun, would easily be compensated for at the end of the day.
Regardless if i run my VM or LM, i always do a fast strippingrun on my potstill.
I draw the foreshots by the drip and then crank up the power, collecting all the way down to 20% ABV.
To give you a idea of how fast i run, you can watch the video of a strippingrun here: http://1drv.ms/1F4TEAa" onclick="window.open(this.href);return false;" rel="nofollow

Dane - I have enjoyed this video before. Im always impressed how much work you get out of that little pump!

All in all - I appreciate everyones help in the thread. I think I have a pretty good feel for the LM. Im going to keep running it for a while to get a good practical understanding of mine and the LM in general. Those flutes sure are pretty though...

[rgreen2002]

Nice speed there DS. I get about the same rate, maybe a little faster when I strip using my keg still.

To the OP: having done both strip and spirit runs, and single runs. If timed that it actually takes less time, to strip and then re run than it does to single run if I want vodka.
Takes 7+ hours to single run to 94-95%. Or I can do a strip, collecting down to 20% in 2 1/2- 3 hours. And then spirit run at 93-94% in about 3 hours.

MM- sorry I jumped the "Submit" gun. So you're saying you could get a high proof spirit in a single run from the LM, but it just takes a long time (probably due to the low rate)... If this is the case I understand that concept completely...

[Monkeyman88]

Yes. You can get a high proof. And yes it takes a very long time.

[rgreen2002]

Yes. You can get a high proof. And yes it takes a very long time.

LOL..Gotcha

[bearriver]

NGS or GNS is a term that often refers to a highly rectified white spirit from a mega distillery. Often it is sold here in the states in 300 gallon plastic IBC totes to startup distilleries for further "refinement" or its used to blend things like brandy. It is produced through continuous columns and with the intention of further processing/rebranding into retail markets. Almost all of this stuff comes from the same few sources.

Thats my take, so back it with a grain of salt.

For those of you at home, go get a bottle of everclear (GNS) and water some down to 80 proof. Now take a drink of that and see if you don't agree... You can and should do better than that crap

[drmiller100]

. At high output rates the flooding starts at the top of the column, not the bottom, ..

How do you know this? I never could figure out where flooding started.

Also, I always thought if you add up the time for stripping runS plus a product run it was just faster overall to make one run and go from 10 percent to 95 percent.

Took me a bit to figure out the column though.

[Monkeyman88]

Some people run glass columns and can see exactly what's happening during a run. Also sight glasses top and bottom.

[rgreen2002]

Some people run glass columns and can see exactly what's happening during a run. Also sight glasses top and bottom.

+1... there are a few great posts showing the sight glass in action. It helped me to really understand the idea of flooding the column and how exactly heat changes the column.

http://homedistiller.org/forum/viewtopi ... =2&t=54029

T-Pees vid is at the top and White_Lightning_Rods is at the bottom. In the middle take a look at the fogging during the tails... as far as identifying tails...it doesn't get much easier than that in my mind.

Mine is coming tomorrow...

[drmiller100]

that's really cool!!! THANK YOU!

[rad14701]

. At high output rates the flooding starts at the top of the column, not the bottom, ..

How do you know this? I never could figure out where flooding started.

Also, I always thought if you add up the time for stripping runS plus a product run it was just faster overall to make one run and go from 10 percent to 95 percent.

Took me a bit to figure out the column though.

With my dual reducer LM rig it definitely starts at the top... High amounts of fast moving vapor and saturated structured packing doesn't allow the reflux to return down in the column so the spirits build up in the reflux condenser chamber until they overflow out the top or are projected out forcefully by built up pressure... The smaller the reflux return/vapor pipe, the more likely that flooding can happen... I have problems with a 3/4" vapor throat in a 1.25" column and the problem would be even more prevalent if, for instance, you had a 2" column and a 3/4" vapor throat... The same goes for dual slant plates spaced too closely together... I partially remedied the problem by adding an external reflux return line so only vapor comes up through the throat and reflux returns down the external tube before it overflows down the throat...

[drmiller100]

my big still was 3 inch column with 3 inch vapor throat. (smiles.......)

When I pushed it HARD, I always thought it would start backing up at the very bottom, but had no way to really tell.

[bearriver]

I partially remedied the problem by adding an external reflux return line so only vapor comes up through the throat and reflux returns down the external tube before it overflows down the throat...

That is not too dissimilar from my solution, which also eliminated splashing at the plates.

[der wo]

With my dual reducer LM rig it definitely starts at the top...

I also had this problem with a concentric design. But my vapor collar for the 2" column was ID 18mm, that's less than 3/4", it was a stupid idea. I build a new LM with an external reflux line.