Improving a pot still ?

[sergiolis]

I'm stripping about 46L of Allbran in my 50L keg. My maximum speed is 1900W because if I push more power I get a huffing sound at the output of my Liebig.
It is a Liebig 1m long with a 22mm jacket and 15mm inner tube, so I have a water layer of 5mm.
I would like to speed up a bit my stripping runs so I was thinking to enlarge my Liebig to avoid the gurgling sound.
I could build a Liebig 28mm jacket and 22mm product tube.. Then I would have a 4mm of coolant water layer.
I would like to hear your opinion about it. I think if I have a wider space for the vapour I could avoid the huffing (to a certain extent) and I could increase the power and the flow-rate a bit.
thanks a lot in advance.
Ohh I forgot it... I would roll a wire around the inner tube too to increase efficiency...
Thanks a lot in advance

[Euphoria]

Your picture is a bit fuzzy, but it looks like your Liebig may be undersized.

[Monkeyman88]

How hot it the water coming out the Liebig?

[Yummyrum]

Surg, I had a very similar liebig .it was 900 mm long jacket but I could strip on gas roaring its head off and get well over 10 liters an hour .
Huffing isnt really an issue especially on a strip run .You could try adjusting your water flow rate .There is a fairly critical point where the alc is coming out warm to hot but still fully condensed .
This reduces or almost elimenates huffing .

[NZChris]

The gurgling sound is likely occurring in the 15mm rising section, not the Liebig.

[sergiolis]

Hi guys,
Yummyrum, 10L an hour? that's really a lot... I can't even imagine that huge speed...
The water flow-rate is very small and the water is coming out really hot, I didn't measured it but it's about 55ºC. The alcohol I'm collecting is a bit warm...
NZChris, How could I know where is located the huffing issue? If I could see where it is I will fix that part. If is where you say I could fix it soldering a bigger tube there.
I know many members here are using a Liebeg even smaller of my size with no issues, so the problem must be somewhere else.
My column is a 2" reduced to a 15mm tube.

[NZChris]

Huffing and gurgling are different issues with different symptoms. Which have you got, or do you have both?

[sergiolis]

Ummmmhh my english is terrible, but I think is Huffing. Something like continuous air puffs. However today I put a mirror very near the output product tube and I could see a small stain of vapour. So I suppose a small quantity of vapour is escaping meanwhile is huffing.

[Truckinbutch]

Coolant water and heat input have to be balanced . You should have cold water going in the bottom and warm to hot coming out the top . The more heat you put to the boiler - the more water flow you need to keep that balance .

[der wo]

After the column (54mm?) go to 28mm. At the last possible point before the liebig reduce to 22mm. And then the 28/22-liebig. 1m length for max 2500W. 28/22mm is perfect for a potstill between 1500 and 3000W. I use this mesuarement with max 2600W. The 4mm water layer is enough.

[sergiolis]

Oh der wo, That's exactly the answer I was expecting because is precisely my plan. Thanks a lot der wo.
Sorry about the mess but I could see 2 more options.

The first one is the Samohon pot still. With this one I could keep my liebig...

SAMOHON Pot Still.pdf

(219.81 KiB) Downloaded 221 times

The second one and the cheapest one is to continue after the 2" tube with 28mm until my current liebig again.
Maybe someone could tell me wich one is the best.
Thanks a lot

[NZChris]

Do you really need a 15 or 28mm riser? You could do away with that section without affecting the quality of the product. The small change in the angle of the Liebig to get the spout height you need wouldn't make much difference to efficiency, or you could raise the boiler to get the height you need and so that you can install a spigot at a height that allows you to get a bucket under it for fast, safe, recharges. I can get the heat back on my pot for the next strip in about seven minutes.

[Yummyrum]

Hi guys,
Yummyrum, 10L an hour? that's really a lot... I can't even imagine that huge speed...
.

Heres a link to another forum where I upgraded my head which looks a bit like yours to what I thought was going to make a huge difference but made bugger all . At that time I guesstimated I was running 2700 watts and pulling 6.6 Liters per Hour . I was using a combo of 1400 watts electric and single gas ring . Since upgrading to keg and 3 ring burner with High Pressure Regulator , I could easily strip at 10-12 Liters per hour .

Heres the pics from that link if you can't see them

I subsequently built another pot head which was 25mm over 19mm ( 1" over 3/4" ) and its quite a bit longer .....it still huffs like a bastard but it can strip at almost 20liters /hour ...but not quite

Here's the vinegar run

[der wo]

Huffing is not so easy. Someone has a small condenser and no problems, another one has to rebuild.
First I would replace the long 15 section with 28. At the last possible point (after the last angle) I would reduce to 22 and then to 15 and then connect your old condenser. This setup will function better, but it's not sure, that it will function perfectly with 1900W. So perhaps you will need the new condenser too.
According to the reliable calculator on the parent side 1900W would need with 15mm OD inner tube 116cm length, with 22mm OD only 75cm. If you decide for a new condenser, perhaps you could shorten the riser as NZchris mentioned.

[StillLearning1]

Unless I missed it, nobody has recommended that you stuff the vapor tube with SS or copper scrubbies. My Liebig is only 28 inches long and it makes a world of difference on mine.

[der wo]

The 4mm water layer is enough.

Edit: It's only 3mm with 28 and 22mm OD pipes. But that's still enough water layer.

[sergiolis]

Thanks a lot guys,
It's a difficult decision but I like the Samohon option because the 90º angle is 54mm and then I could reduce it to my old Liebig.... If I can hear still huffing I will change the liebig too...
I will ask for the price... The 54mm accesories are very expensive here.
Thanks a lot der wo for your opinion but I have the feeling that the 54mm 90º angle could be better
Yummyrum, your speeds are awesome but I would like to avoid huffing because as I could check it a small amount of vapour is escaping when huffing...

[der wo]

I have the feeling that the 54mm 90º angle could be better

Yes, you are right. But as you mentioned it's expensive. The question is always, whats the weakest point in your setup and with what effort (money or sweat) you get what improvement. Now the 15mm section I think is the weakest point. If you replace it with 28mm (or with 54mm), the liebig will be the weakest point.
Fittings are replaceable. Drill at the top a 28mm hole in the side of the column, solder a 28mm pipe in and a lid on the column and you have the angle and the reducer.

[sergiolis]

yes, to continue with 28mm and to make a test is a very cheap option to try. On the other hand I trust on my Liebig because is very efficient. I need just a very low stream of water to hold 1900W... so if the huffing is not caused by the Liebig maybe a wider connection of 28mm to the Liebig will be enough and it's really cheap to try it. I could make a test but if the huffing is still present I think I will need the 90º-54mm. I will test it soon...
thankS A lot

[der wo]

I think, if it's still huffing with 28mm, you will need a larger liebig. But perhaps I'm wrong, I have never used a 15mm-liebig.

[CR33G3R]

Unless I missed it, nobody has recommended that you stuff the vapor tube with SS or copper scrubbies. My Liebig is only 28 inches long and it makes a world of difference on mine.

Just stuff a little scrubbie in the end of that thing and it will stop huffing. Your liebig is more than long enough.
I find the calcs. on the parent site to be off for figuring liebig size.

[sergiolis]

I put a piece of copper scrubbie at the output of the Liebig. But it's not a solution, It reduces the sound but the huffing is there anyway. We can hear the echo of the sound at the end of the output tube but the problem is not located there....
der wo, many members here use a 1/2" - 3/4" liebigs and as i could see they work nice..., That's why I think the issue must be somewhere else

[der wo]

Perhaps try the scrubbie at the beginning of the liebig. In my expierience it helps more than at the end.

Yes I know, most use 1/2 + 3/4. And I wonder every day. I first had the inner tube OD 18mm and after that 22mm. It's such a huge difference better operation. But yes, most use it and they are happy, so perhaps I'm wrong, but I cannot explain it.

For me, the calculator worked always perfectly. With a scrubbie you can go shorter.

[still_stirrin]

...I subsequently built another pot head which was 25mm over 19mm ( 1" over 3/4" ), and its quite a bit longer...it still huffs like a bastard but it can strip at almost 20liters /hour...but not quite...Here's the vinegar run...

Yummyrum, that thing looks like a "fire breathing dragon".

I'd suppose at those takeoff rates, you'll smear the heads all the way to the "other end".
ss

[still_stirrin]

I put a piece of copper scrubbie at the output of the Liebig...It reduces the sound but the huffing is there anyway. We can hear the echo of the sound at the end of the output tube but the problem is not located there...

Is the problem "huffing", which is caused by premature vapor collapse at the product condenser's vapor inlet?

Or, is it "puffing", which is caused by incomplete vapor condensation at the product outlet, usually due to too much heat input for the vapor velocity through the condenser?

The former condition (huffing) can be solved by reducing the coolant flow velocity. The vapor inlet to the condenser will be very hot, almost too hot to touch, but the product should condense within the condenser if there is adequate surface area for the vapor to condense on (length x circumference of the vapor pipe).

The latter condition (puffing) can be solved by reducing the input heat so the boil rate slows down a little. You can also improve knockdown and condensation cooling with a little scrubbie in the vapor tube in your product condenser (which you've already tried).

Huffing and puffing seem like the same conditions, but they are different and should be resolved differently.

Proper vapor speed into the condenser helps efficiency of the condenser to knock down the vapor. If your column comes off the boiler at 54mm and you reduce down to 13mm, I would expect the flow to choke....literally go sonic with the mass flow limitation in the small diameter pipe.
ss

[CR33G3R]

I agree with SS. Maybe the easiest fix would be to put a 90 deg elbow the same size as your column. (just like the PDF that you posted).
I have built all my stills like this and have never had the problems that you are. (change of direction same size as column)
I run a 24 inch 1 inch over 3/4 and it can handle everything I throw at it. i run it with just a small piece of ss scrubber in the end maybe 2 inches long.

Der Wo what is the heat transfer coefficient that you use in the calculation. I think that the one provided for a liebig is wrong. I am interested to hear your input on this.
We can talk about this through PM if you would like so as not to hijack the thread.

[der wo]

No rocket science. I simply found out (I have build three potstill-liebigs in my career), if I use the calculator with the preset settings (water input 15°C, output 50°C, vap temp 82°C and 850W/m²C) and use a smaller liebig than calculated, huffing will start.
I started my journey with a small potstill and upgraded size and power step by step. And before building a new condenser, I tried the higher power with the old liebig first. That did not function very well, but I had success, to fix the problems with a turbulator.
The data (I always used hotplates):
- First I had 1500W. 70cm, 16mm ID inner tube, worked without problems.
-The same condenser with 2000W was huffing strongly, but no vapour escaped. I could fix it with a scrubbie.
-The new liebig: 81cm 20mm ID had no problems with 2000W without scrubbie. But now with 2600W I have a little huffing, but can fix it with the scrubbie.

[skow69]

That's good data, der wo. I love to see quantified empirical evidence.

[sergiolis]

that's an interesting conversation!!!
still_stirrin , The problem is "huffing", which is caused by premature vapor collapse at the product condenser's vapor inlet
As I said everything works great until 1900W, but I would like to get more power and product flow-rate.
I Think I will change the 15mm section until the liebig for a 28mm section. It will be very cheap to try that option.
I will see the difference and if I'm not satisfied yet I will try with a 54mm elbow.... I think this is a reasonable option.
The further option could be to change also the Liebig for a bigger one as der wo has demonstrated but maybe it's not necessary....
let's see soon
thanks a lot guys

[Yummyrum]

I'd suppose at those takeoff rates, you'll smear the heads all the way to the "other end".
ss

LOL , still stirrin , yeah only strip hard on strips ....but never that hard , it was just a test to see what it could handle , I had flames up the side of the keg to nearly the top and was too scared to push it any harder

BTW : sergio, all three pot heads I made all huffed , so it would appear to me that condenser size and reduction sizes has little to do with it . Incidentally I only experience huffing at the end of the run .That is when I find backing off water flow helps .