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Yummyrum wrote: ↑Thu Sep 08, 2022 1:30 am What always gets me is that 4"is 4x the area as 2" .
So is it not the equivalent of 4 x 2" columns in parallel or side by side ?

If a 2" column can run with 2kw , then 4 of these would use a total of 8kw .

If each column can produce say 95% without flooding @ say 1l/hr then surely four in parallel would be producing a combined output of 4l/hr @ 95% .

So why is it when we take away the pipes and combine 4 x 2" columns into one 4" column , that it all turns to shit and floods and makes low abv and needs to be taller and need different size packing ?????

The difference is when you use four 2" columns, each 2" column will be running at 1/4 the power of a 4" column so to speak and requires smaller structured packing. 2" columns would have approx 1/4th the amount of falling reflux as well as 1/4" the amount of rising vapor. 4" columns run at 4 times the power and needs larger structured packing otherwise it floods. Think about the amount of vapor rising through a FINE structured packing meeting all that reflux trying to make its way down. This is the same principal that causes relatively fine screens flood columns.

Otis appears to be using some of the small bits that are sized for a 2" column inside of his 4" column. That size flooded my 3" column so I would expect it to flood in a 4" column. I believe the perforated plate and the fine rock is the main problem. If he replaces that with a wide open support, ditches the tiny rock THEN tests the larger rock all on its own ... if it still floods then he needs larger Lava Rock. He's using the same size I use in my 3" which works flawlessly. His column has twice the cross-sectional area than mine though.

Salt Must Flow wrote: ↑Thu Sep 08, 2022 8:15 am The difference is when you use four 2" columns, each 2" column will be running at 1/4 the power of a 4" column so to speak and requires smaller structured packing. 2" columns would have approx 1/4th the amount of falling reflux as well as 1/4" the amount of rising vapor. 4" columns run at 4 times the power and needs larger structured packing otherwise it floods.

I agree that the 4" has 4x the vapour and 4 x the reflux as a 2" ( with the boiler power increased by 4 also )
But then that extra vapour entering the column is divided or shared across 4x the surface area . At the same time , the extra reflux at the top of the packing is now spread into 4x the amount of packing .
So surely each square inch of packing should meet the same amount of rising vapour and for that matter falling reflux regardless of whether it's in a 2" running 2kw or a 4" running 8kw .


Perhaps channeling or uneven distribution of vapour and reflux becomes more of an issue as we increase the diameter

Yummyrum wrote: ↑Thu Sep 08, 2022 1:25 pm

Salt Must Flow wrote: ↑Thu Sep 08, 2022 8:15 am The difference is when you use four 2" columns, each 2" column will be running at 1/4 the power of a 4" column so to speak and requires smaller structured packing. 2" columns would have approx 1/4th the amount of falling reflux as well as 1/4" the amount of rising vapor. 4" columns run at 4 times the power and needs larger structured packing otherwise it floods.

I agree that the 4" has 4x the vapour and 4 x the reflux as a 2" ( with the boiler power increased by 4 also )
But then that extra vapour entering the column is divided or shared across 4x the surface area . At the same time , the extra reflux at the top of the packing is now spread into 4x the amount of packing .
So surely each square inch of packing should meet the same amount of rising vapour and for that matter falling reflux regardless of whether it's in a 2" running 2kw or a 4" running 8kw .


Perhaps channeling or uneven distribution of vapour and reflux becomes more of an issue as we increase the diameter

Yup, you're right. I totally get what you're saying. It's a brain teaser.

I've seen multiple topics like this one for instance where StillerBoy has listed recommended sizes of Lava Rock for 2" and 3". The pattern is larger the column, larger the rock. I tried the recommended size for 3" and it works wonderfully at 2750W and higher. I got curious and tried the recommended size for 2" in my 3" hoping it would work better and all I know is that I just couldn't keep it from flooding every time with 2750W. Now I'll admit that I've never tried the smaller rock with a 2" column, but I assume many others have and could tell if it flooded on them.

StillerBoy
Lava rocks in the right size for column, like 3/16 - 1/4" for 2" or 1/4 - 5/16" for 3" will work very well..

Yummyrum wrote: ↑Thu Sep 08, 2022 1:25 pm

Salt Must Flow wrote: ↑Thu Sep 08, 2022 8:15 am The difference is when you use four 2" columns, each 2" column will be running at 1/4 the power of a 4" column so to speak and requires smaller structured packing. 2" columns would have approx 1/4th the amount of falling reflux as well as 1/4" the amount of rising vapor. 4" columns run at 4 times the power and needs larger structured packing otherwise it floods.

I agree that the 4" has 4x the vapour and 4 x the reflux as a 2" ( with the boiler power increased by 4 also )
But then that extra vapour entering the column is divided or shared across 4x the surface area . At the same time , the extra reflux at the top of the packing is now spread into 4x the amount of packing .
So surely each square inch of packing should meet the same amount of rising vapour and for that matter falling reflux regardless of whether it's in a 2" running 2kw or a 4" running 8kw .


Perhaps channeling or uneven distribution of vapour and reflux becomes more of an issue as we increase the diameter

I totally agree with your thoughts.

One assumption I have is how I run my stills. I hate to bring g it up but back to the definition of flooding.
Otis seems to run his still hard as he can with an upper limit of liquid flooding the column to the point liquid comes out the top of the packing.
I've mostly run mine to the point there is no significant liquid in the packing. Yes, liquid drips down bit it isn't like there is a quarter cup of liquid in an area in the packing. For mine, a limit is I can hear the marbles rattling in there. That is the absolute max.
I wonder if he has so much liquid in his column everything is basically saturated and steam is being forced up through homogeneous liquid making it effectively 5 or 6 plates instead of the 50 effective plates I have.
If I were tuning a 3 inch column, with everything adjustable, and I was wanting azeo, I'd
1. Bring it to boil
2 turn the heat to something like 3000 watts. Something that is plenty safe.
3. Let it full reflux and pull the heads
4. Start pulling product while maintaining azeo
5. Find the max rate of azeo you can pull
6. Turn up the power 10 percent
7. Tune by adjusting reflux to maximize azeo product
Hopefully more power means faster product rate
Repeat 6 and 7 until the column crashes.

When this happens you won't get azeo at a decent rate until you turn the power down.

This how I did it. Then I changed packing and ran it again. Eventually I found you can use anything for packing but some packing requires less packing height than others and some packing crashes at different power levels.

What are your thoughts?

Yummyrum wrote: ↑Thu Sep 08, 2022 1:30 am What always gets me is that 4"is 4x the area as 2" .
So is it not the equivalent of 4 x 2" columns in parallel or side by side ?

If a 2" column can run with 2kw , then 4 of these would use a total of 8kw .

If each column can produce say 95% without flooding @ say 1l/hr then surely four in parallel would be producing a combined output of 4l/hr @ 95% .

So why is it when we take away the pipes and combine 4 x 2" columns into one 4" column , that it all turns to shit and floods and makes low abv and needs to be taller and need different size packing ?????

Ya got me there Yummy. I can’t explain it, what maths or voodoo are involved, but what I have read and what I have experienced says it’s true. More diameter requires more height. This is no different that folks saying you need a 15-20:1 ratio of height to column diameter to hit azeo.

drmiller100 wrote: ↑Thu Sep 08, 2022 4:01 pm .......
One assumption I have is how I run my stills. I hate to bring g it up but back to the definition of flooding.
Otis seems to run his still hard as he can with an upper limit of liquid flooding the column to the point liquid comes out the top of the packing......

What are your thoughts?

No I don’t. I actually run at lower power than most I read of. For example, I find the upper limit of a 2” to be south of 1500w and around 3500 for a 3”. And I’m not a fan of running flooded, or semi-flooded.

I’m working to eliminating the flooding. How did you miss that?

OtisT wrote: ↑Thu Sep 08, 2022 6:20 pm

drmiller100 wrote: ↑Thu Sep 08, 2022 4:01 pm .......
One assumption I have is how I run my stills. I hate to bring g it up but back to the definition of flooding.
Otis seems to run his still hard as he can with an upper limit of liquid flooding the column to the point liquid comes out the top of the packing......

What are your thoughts?

No I don’t. I actually run at lower power than most I read of. For example, I find the upper limit of a 2” to be south of 1500w and around 3500 for a 3”. And I’m not a fan of running flooded, or semi-flooded.

I’m working to eliminating the flooding. How did you miss that?

Im stuck on you can't get azeo with 50 inches of packing.

Why do YOU think that is?

OtisT wrote: ↑Thu Sep 08, 2022 6:20 pm

drmiller100 wrote: ↑Thu Sep 08, 2022 4:01 pm .......
One assumption I have is how I run my stills. I hate to bring g it up but back to the definition of flooding.
Otis seems to run his still hard as he can with an upper limit of liquid flooding the column to the point liquid comes out the top of the packing......

What are your thoughts?

No I don’t. I actually run at lower power than most I read of. For example, I find the upper limit of a 2” to be south of 1500w and around 3500 for a 3”. And I’m not a fan of running flooded, or semi-flooded.

I’m working to eliminating the flooding. How did you miss that?

3500 watts on 3 inch with 3/8 inch rocks seems like a LOT to me.
I run 4000 watts on 3 inch 1/2 inch marbles and that is maxed.

I'm not trying to be a dick or argue, but rather argue to learn .

Respectfully doug


On edit. 3/8 at 3500 might be ok. 1/4 inch too much. Thougjts????

drmiller100 wrote: ↑Thu Sep 08, 2022 6:52 pm

OtisT wrote: ↑Thu Sep 08, 2022 6:20 pm

drmiller100 wrote: ↑Thu Sep 08, 2022 4:01 pm .......
One assumption I have is how I run my stills. I hate to bring g it up but back to the definition of flooding.
Otis seems to run his still hard as he can with an upper limit of liquid flooding the column to the point liquid comes out the top of the packing......

What are your thoughts?

No I don’t. I actually run at lower power than most I read of. For example, I find the upper limit of a 2” to be south of 1500w and around 3500 for a 3”. And I’m not a fan of running flooded, or semi-flooded.

I’m working to eliminating the flooding. How did you miss that?

Im stuck on you can't get azeo with 50 inches of packing.

Why do YOU think that is?

I thought I already answered my thoughts on this above.

Although it’s not a question I have asked and it is not the issue I am trying to solve here (getting to azeo) I’m convinced it’s because I don’t have enough packing height. If I had unlimited height, I would go with the larger rocks and add another 3’ or more to height to get to azeo. Repeating the rule of thumb I’ve seen shared here on HD for years, and something that my own testing has proven out so far, I would need a packed 4” column section 60” to 80” (4”*15 to 4”*20j of height to get near azeo. I saw the height difference need change going from 2” to 3”, and I am seeing it again going to 4”.

Duplicate message.

drmiller100 wrote: ↑Thu Sep 08, 2022 6:58 pm

OtisT wrote: ↑Thu Sep 08, 2022 6:20 pm

drmiller100 wrote: ↑Thu Sep 08, 2022 4:01 pm .......
One assumption I have is how I run my stills. I hate to bring g it up but back to the definition of flooding.
Otis seems to run his still hard as he can with an upper limit of liquid flooding the column to the point liquid comes out the top of the packing......

What are your thoughts?

No I don’t. I actually run at lower power than most I read of. For example, I find the upper limit of a 2” to be south of 1500w and around 3500 for a 3”. And I’m not a fan of running flooded, or semi-flooded.

I’m working to eliminating the flooding. How did you miss that?

3500 watts on 3 inch with 3/8 inch rocks seems like a LOT to me.
I run 4000 watts on 3 inch 1/2 inch marbles and that is maxed.

I'm not trying to be a dick or argue, but rather argue to learn .

Respectfully doug


On edit. 3/8 at 3500 might be ok. 1/4 inch too much. Thougjts????

No problem asking. 3500w was the top end of the range for power I used on my 3” column using copper mesh, and I think my ceramic raschig rings were closer to 3200w. I never ran rocks in my 3” so I can’t share any info on that.

Newer folks should use the guidelines as a starting point and adjust from their to suite their individual needs. Packing size, type, insulation, wash type, quality of product, reflux temp/amount, etc. can all impact the max power a person wants to run at. When new folks ask me, I tell them to start below the max and work up so they can see the impact of power changes on results and learn when they reach too much power. Maybe start at 1k for a 2”, 2k for a 3”, and 4K for a 4”. You should be able to get your best ABV at those levels with adjustment, then watch how things change as power is increased until you see a decline in quality when you het too much power.

Also to note: My tolerance for power error could make this +/- 500 watts easily. My meter went bad years ago, so I’m working from markings around the knob I made when the meter was functioning. Otis

I think 3k-3.5k is about 20 ft/sec vapor speed in a 3”. Been a while since I checked. As far as azeo, needs more height. I have read a minimum of 15 plates or equivalent. 50” would need a 3” hetp to do that. I expect that the packing is closer to 4+ in hetp, which would make it need to be 60+ of packing. I found 20+ plates was a lot more stable and even then could not hit true azeo. Could run low 190’s, but that was it.

Hi BlueFish. You are correct about vapor speed. That is close to 20’/second in a 3”.

I agree with you also that I would need more height to hit azeo, which is why I’m not expecting to hit azeo with what I have. I’m just trying to find the best separation I can get out of my 4” with a maximum packing height of 52”. The smaller rocks made a big difference versus the larger rocks. I have bags of stainless steel shavings off of a lathe that I may try some day, way down the road, but right now I have my hands full making a new bottom plate that will let me run the smaller rock at around 5000W. The small rock was top flooding at 5500w, and I don’t expect a new bottom plate will fix that.

Some day I will have a taller home. Azeo is just a 3’ spool away.

Otis

Otis, a better hetp is a worthwhile goal. Look forward to hearing your results. I searched quite a bit and never was able to get under 4” and that was scrubbies. Tried spp, marbles, scrubbies. I never did try lava rock as I never felt I could be sure it was free of heavy metals, can’t just go out and buy lab grade or food grade lava rocks. Not to say it’s unsafe, but never felt comfortable to sell a product made using unknown sourced rocks.

I agree with the above post on what might leach out of lava rock. This has nothing to do with distilling. In the past I made custom tanks for hydroponics. In a new system I was trying out I was using lava rocks as my medium. I thought the poor performance was due to the new design. 2 runs , 6months later I figured out it was the rock harming my plants. Switched mediums and the system worked as I thought it should.
It seemed funny to read criticism about a little plastic exposure but no problem percolating thru lava with solvents.
JK
https://www.researchgate.net/publicatio ... ns%20extra,)%20%5B18%2C%2019%5D. only one lava source location, limited I know

Jaliscokid wrote: ↑Mon Oct 31, 2022 9:39 am I agree with the above post on what might leach out of lava rock. This has nothing to do with distilling. In the past I made custom tanks for hydroponics. In a new system I was trying out I was using lava rocks as my medium. I thought the poor performance was due to the new design. 2 runs , 6months later I figured out it was the rock harming my plants. Switched mediums and the system worked as I thought it should.
It seemed funny to read criticism about a little plastic exposure but no problem percolating thru lava with solvents.
JK
https://www.researchgate.net/publicatio ... ns%20extra,)%20%5B18%2C%2019%5D. only one lava source location, limited I know

Strange you posted that . It was the first thought that I had when folk started using rock ….. it’s full of all sorts of stuff .
I guess in most cases its used in the ascending path so one would hope that any heavy metals will fall back into the boiler .
Having said that , Mercury will evaporate at room temps .

I tried rock for a while but i went back to scrubbers as I round them better , which was in a way good for me as I never felt comfortable using bit .My gut instinct is that it is not good .

However , many have been using it for a few years now and there seems ti be no reported cases of heavy metal poisoning . But then as your link suggested , different geological areas would contain different minerals .

I hear your concerns with what is in the rock. No way to know without testing. The study referred to testing soil in a volcanic region, not the rock, so who knows how relevant that study is. As was mentioned, where it comes from could matter, and what type of rock could matter too. The stuff I have is not lava rock, but cinder rock. Potato, potato?

All that is moot for me now. Something ruined my rock so I just purchased 11 liters of the 1/2” sized Siporax bio filter medium some others here on HD have been using. That stuff is made from recycled glass. It’s very light by volume and very porous.

Otis

Im stuck on you can't get azeo with 50 inches of packing.

Why do YOU think that is?
[/quote]

Hetp does not change by column diameter. If Odin is correct and you need a minimum of 15 plates to reach azeo (I think that’s actually a bit low), then 50” needs a hetp of just over 3” to hit 15 plates. Other than a few people running SPP I have not seen any proof that any other packing material consistently achieves a sub 3” hetp. Not to say it can’t be done, but scrubbies won’t do it, marbles won’t do it. Also on the 20:1, I think that is more of a slenderness ratio than does it hit azeo. An 80” 2” column is too narrow and you would be better off with a larger column for that height.

Adding a link to my condenser build for this column. I can never find it easily by searching but I do find this thread, so here it is Otis:

Otis’ 4” Column Condenser - RC / Dephlegmator Build. viewtopic.php?t=81513