Glass Marbles for Reflux Column Structured Packing

[still_stirrin]

I'm running my 2" column packed with 1/2" marbles in the morning. I'll report observations tomorrow.

Cheers.

ss

[waster]

Roddy commented about a 'sweet spot' for tuning the power input for marbles. Rad--or anyone else--what are the considerations when looking to optimize performance of a given packing. Is there something special or different about tuning power input to a high-thermal-mass packed column (marbles , rocks, ceramics, glass, SPP) compared to low-thermal-mass packed column (mesh, scrubbies)? Or do you always want to set power at 80% (or some other fudge factor) of flooding?

[bearriver]

I find just below flooding works well for scrubbers. That will be my starting point with marbles. Find what point at which the column will flood, then back it off a frogs hair till the flooding ceases.

A sight glass like what hound dog uses would be nice for this.

(Bear on his bathroom break)

[still_stirrin]

I'm running my 2" column packed with 1/2" marbles in the morning. I'll report observations tomorrow.

Cheers.

ss

Mid way through the spirit run with 39" of marbles in my 2" column and I've been pulling 190 proof since the foreshots. I've taken off about 8 pints in the 2 hours since it stabilized. The 1/2" marbles seem to be working great in my column.

ss

edit: added photo

[waster]

SS--Wow, that's excellent. Did you do anything different as far as setting power compared to your old packing?

[still_stirrin]

SS--Wow, that's excellent. Did you do anything different as far as setting power compared to your old packing?

Nope, just loping along at 950-1000W input. Needle thin takeoff steady since the start. The marbles seem to do the trick nicely.

Of note, the parent site predicted azeo with a 39" (2" diameter) column. Its exactly what I'm seeing.

ss

[rad14701]

SS--Wow, that's excellent. Did you do anything different as far as setting power compared to your old packing?

Nope, just loping along at 950-1000W input. Needle thin takeoff steady since the start. The marbles seem to do the trick nicely.

Of note, the parent site predicted azeo with a 39" (2" diameter) column. Its exactly what I'm seeing.

ss

Are you able to collect at a faster take off rate, or haven't you experimented with that aspect yet...??? I can push more power, provide more reflux, increase my take off rate, and maintain higher purity throughout more of the run...

Sounds like the marbles are working well for you...

[still_stirrin]

Maybe its possible. I haven't tried to push it yet. This is the 1st spirit run using marbles. I'll try a faster takeoff on next run.

But wise mentors have said, "impatience & distilling don't mix". I gotta' believe the knowledge in front of me, including you.

I will try to pick up the pace next time though. I am very pleased with the quality of this run with the glass marbles.

Thanks again (all) for the insight.

ss

[Hound Dog]

I find just below flooding works well for scrubbers. That will be my starting point with marbles. Find what point at which the column will flood, then back it off a frogs hair till the flooding ceases.

A sight glass like what hound dog uses would be nice for this.

(Bear on his bathroom break)

That's just why I put a sight glass in. I have been running that way with lava rock. Got to get another batch going in a few weeks as my stock is getting low. I will probably want to try the marbles to see how they work for me.

I will want to try using them smooth. If a rough surface is much better, I may as well stick with lava rock. It is a very rough surface. But playing around with different stuff is what keeps this fun!

[lampshade]

How do you use a sight glass to detect flooding?

[Hound Dog]

How do you use a sight glass to detect flooding?

I put a sight glass at the very top of my column just above where my packing stops. You can see the liquid bed rise up to the sight glass and just cut back on the heat input a bit to bring it back down the column. No guess work involved. I put another one across from the bottom plate (boka) to see the reflux but find that it is more of a novelty than really useful.

[waster]

So to summarize the great work of others

Rad
1.25" column
5/8" marbles (column-to-marble ratio =2.0)
1.5 LPH @ 95%

Still_stirrin
2" column
0.5" marbles (column-to-marble ratio =4.0)
2.0 LPH @ 95% (hasn't tried to increase power yet)

Lester
2" column
11mm marbles (column-to-marble ratio = 4.5)
3.5 LPH @ 95" (cleaning run)

1. Rad's column has about 1/2.5 the cross section of the others, so his takeoff rate scales to ~3.8LPH, right in line with Lester's cleaning run.

2. the ratio of column diameter to marble is related to void. for high ratio, the void should drop to 26%. But for low ratios, like Rad's, the void increases, in his case to ~40%. So Lester's result suggests that marbles work over a pretty big range of voids. I find this very surprising--I would have thought entrainment and flooding would be likely for higher column-to-marble ratios with their lower void and higher vapor speed.

I have 6mm and 16mm glass coming. Hope I didn't make any errors here, but I just wanted to summarize what I've been learning from others on this thread.

(PS: I tried the rings I posted above but flooded at 0.9LPH, MAYBE because of a mod I made in the condensor--have to try again)

[lampshade]

(PS: I tried the rings I posted above but flooded at 0.9LPH, MAYBE because of a mod I made in the condensor--have to try again)

Pls do re-run with raschig rings. Your preliminary findings are disappointing. But if you still get the same results, this may suggest that Dr. Rad is onto something profound: marbles are superior to raschig rings. "Who would have thunk."

My two cents: If raschig rings flood when marbles don't, for the same upward vapor throughput (i.e heater power), the reason may be that the geometry of the marbles provides for improved downward throughput of the liquid in the column.

If my theory is correct, another way to look at this is as follows. Maybe a column of scrubbies or raschig rings holds depleted water in the column, instead of liquid that is ethanol plus water. This column thus contains mostly water instead of ethanol+water.

[waster]

lampshade,

I hope to. Since I have two sizes of glass coming, I want to do a really nice experiment with the same water + feints simulated wash recycled for as many packings as I can. Good news is that I have enough alcohol (in the form of beer and cider and wine) to drink while re-distilling the simulated wash..... Now if the wife and kids will only cooperate. If I had to guess, I would say 8mm rings will outperform 6mm glass, but that 14-16mm standard marbles will be better than both. Rad must be right: for dense packing its about the void. That's why Lester's result is so interesting/confusing.

Regarding your theory, I agree. When I imagine how marbles work, with low void and smooth surfaces, I see fast vapor winding upwards and fast liquid draining downwards. We all know about HETP, but if it takes 10 cycles to get a certain purity, then somehow the SPEED of those distillations must come into play when talking about LPH. Put another way, I would guess that if you measured the head and base (top and bottom) temperatures of a column, ie the gradient, it would be smaller for marbles and bigger for rings/scrubbies. Of course, I'm still trying to wrap my head around all this.

[lampshade]

If my theory about marble drainage is correct, then this would imply that the column must be driven hard to prevent the column from becoming empty. And if that is true, then means should be provided to detect flooding (sight glass), since the column should be operated just below flooding.

[thecroweater]

I don't think so marbles were all the rage 20, 30 yrs ago and I never heard they were overly subject to dumping

[badbird]

Not even 20 years (for me anyway), The first CM reflux still I built in around 1999 used marbles in a 1.5" column and produced quite reasonable results considering the packed section was probably less than 24" high. The marbles did get changed over to scrubbers eventually as they became popular, from memory I got a couple extra % ABV after the change but the still design was a LONG way from optimum so definitely not a fair test.

For a while I have been thinking of trying out marbles in a tall stripping column for gluggy AG mashes but I guess that’s for another thread.

[Bagasso]

I don't think so marbles were all the rage 20, 30 yrs ago and I never heard they were overly subject to dumping

Maybe it's a glass half empty/half full situation.

Looking at it the other way, maybe they are not overly subject to flooding and in that case smooth surfaces might be better than textured.

[Bagasso]

I would guess that if you measured the head and base (top and bottom) temperatures of a column, ie the gradient, it would be smaller for marbles and bigger for rings/scrubbies.

I think that the opposite might be true for metal packing because the metal would do a better job of transfering heat to the top of the column.

[Brutal]

I haven't run with marbles yet, but it seems like it would be hard to get it to flood. Hard, at least compared to rashing rings or copper mesh. It just seems like it would drain liquid fast.

I guess I have to get off my ass and go put a bok together...

[waster]

Maybe I should clarify what I meant. I did not mean that marbles are subject to flooding or are easy to flood. I meant that to maximize LPH one needs to operate near flooding--any packing can be flooded. So assuming that one keeps cranking up the heating and cooling power until near flooding, one gets to the "sweet spot" for maximum LPH at good purity. The hypothesis is that flooding marbles takes lots of power....

[lampshade]

The marbles did get changed over to scrubbers eventually as they became popular, ...

Do you know why marbles went out of favor (20 years ago???) and were replaced with scrubbers, in popularity?

Maybe the reflux condensers at that time were not as capable as they are today and could not provide enough reflux to match the drainage of marbles. Maybe it was found that scrubbers give a couple of %ABV more, at the expense of LPH throughput, for the equipment that was available at the time.

[rager]

this thread has been great . it has cleared a lot of questions I have about a reflux still. im finishing up my 48 in bok and im thinking about using marbles . I wont have anything to compare them too as far as other packing but ill report back . does anyone have any numbers on how many marbles it would take to fill a 48"x2" bok??

thanks for the great info here

rager

[badbird]

Do you know why marbles went out of favor (20 years ago???) and were replaced with scrubbers, in popularity?

.

I wasn't really following the internet forum stuff much then but my guess is that fashion played its part not much has changed

It would be interesting to see how side by side trials between marbles and scrubbers go for different column lengths, my bet is scrubbers win for the short ones, for the longer ones ??
I don't think reflux condensers where that big a problem back then (except for the horrible cooling pipes through the column style things), mine did 100% reflux on something like 1800W so I was happy enough with it for the 1.5" column. You are probably right about the ABV vs throughput trade-off thing, no doubt I was happy to get that bit closer to azeo.

[thecroweater]

ppl found that they got better results from other starta's that simple , they work just as raschig rings do but a lot of ppl felt there was better packing around.
and promoted that idea. Its my thought that they are likely to be correct how ever its also my thoughts that scuffed marbles would change the game rules and ya may well find they are as good as anything else but I have be wrong before

[DAD300]

There are side by side comparisons for marbles, 2x rasching rings, Scrubbers and a calculator for all diameter and height of columns...do we no longer trust the home page calculators?

Those calculators have always been spot on for me experiments. They certainly show the dif between marbles and scrubbers almost perfectly.

The one and only advantage of marbles would be cleaning them. A rinse from the top would clean them better than any other packing!

Glass is a better insulator than metal. So as the column gets taller, marbles will demand exponentially more power to send vapor to the top.

[waster]

There are side by side comparisons for marbles, 2x rasching rings, Scrubbers and a calculator for all diameter and height of columns...do we no longer trust the home page calculators?
.

Rad in the OP suggests exactly that: higher purity than the calculator gives for marbles.

[Bagasso]

What if the calculator on the parent site is a limiting factor?

No one ever thought to push a column filled with marbles harder because the calc said that it would do poorly and as a result everyones experience matched the calc.

[rad14701]

I always doubted the parent site as far as marbles are concerned... It is my belief that they were given a bad reputation due to theoretical values only rather than practical application... For me they vastly outperform SS scrubbers... Perhaps I should make an attempt to see whether very loosely packed SS scrubbers would perform any better than my standard density... Way too many experiments to try in my currently limited time...

[Bagasso]

Don't remember seeing this mentioned in the thread but wanting to try this out and having to do with what is on hand, I grabbed an 8" piece of 1.5" tube and a bag of standard marbles sitting around.

Placed a cap that happens to have a small piece of .5" tube soldered to the center. Filled with marbles and noticed that no matter how I tilted or shook the tube there is always a space straight up the middle about the diameter of a pencil.