build a better liebig condensor

[ant]

This is not my innovation; a chap called Graham Laming came up with it. I know it from biodiesel use which was why it was designed.

I thought it could find a useful home here as well.

It needs to be vertical or near vertical to work properly.

The "GL Plumber's Delight" vapour condenser

This is a simple, compact condenser which you can make in an hour or two using standard soldered plumbing parts. It can also be made with compression fittings.

It takes up very little space and is efficient, using less water than a conventional straight-through still.

It does this by making the vapour and water streams turbulent, so that they avoid a hot 'core' of vapour forming down the middle of the condenser or cold water on the outside of the water jacket. We are trying to avoid laminar flow, typical of most straight condensers. And we are trying to use less water than a coiled condenser would use.

To create the turbulence, I crimp the inner condenser pipe at regular intervals, at alternate 90 degree angles. See the pics for clearer understanding.

There is very little water in the jacket, the aim being to have fast, low volume water flow with good heat transfer.

The inner pipe is best crimped using mole grips to set a repeatable crimp but pump pliers and good hand eye coordination will work as well.

I used a pump wrench to squash the pipe. Make sure you don't squash it too much - have a small piece of 22mm pipe handy and make sure it will slip freely over the crimps you make. I made mine ever-so-slightly an interference fit in the 22mm pipe, but it was very easy to slide the completed crimped 15mm pipe into the 22mm jacket.

Nick (Twenty4Seven) made a good suggestion - Use adjustable mole-grips to set the crimp depth, so that all crimps will be the same.

You can see how this crimping makes an effective turbulence generator for both the water and the methanol vapour...

The vapour forms a thin rectangular jet, lets say north-south. Then it has to suddenly change to an east-west rectangular jet, and so on, repeatedly down the length of the pipe.

This causes it to make intimate contact with the pipe walls, preventing the effect of having a hot central core of vapour.

[ant]

problems with the pic uploader being very temperamental.

Try again.







Yaay, worked this time. Preview is only showing one thumbnail. There are two pics if you click them.

[Almanac]

In building my Liebig Condenser I soldered a spiral of copper into the water jacket and one into the vapour pipe to create turbulence in both flows but I have to admit this is an intriguing innovation and I, for one, am on my way to my 'distillery engineering workshop' to make one for my pot still.

Nice one Ant

AM

[YHB]

What pot still? - I have obviously missed something.

[ant]

Thanks aidanmac. Bear in mind is should be vertical when you use it. Or near enough. That one was for essentially pot stilling methanol to recover excess after the biodiesel process. You may find that length and or dia is not perfect for ethanol with it's different temps. Let us know how you get on with it. I think it is easier to get better turbulence than the spiral method.

[Capt-Cudellez]

I find when pot stilling having the condenser as near horizontal works best for me, ethanol vapour is denser than air, if I have it too vertical the distillate seems to "drop out" hotter than when I have it on the horizontal plane.

I do have a large bore condenser which maybe makes this problem worse, and I use some packing to act as a turbulator which seems to improve the efficiency.



I now run even more horizontal than this, I get the issues this would cause in a crimped tube, so I guess you have to consider the height of your rig, and the height you will be collecting at.


CC

[ant]

Yes you are having a problem with a hot core of vapour. Exactly the problem this design addresses.

Very pretty rig. Why is shiny so lovely to the eye I wonder?

If you have it horizontal you will have pooling in the lower parts of every other chamber in the core. The ones that are aligned vertically. Or less pooling in all the chambers if they are aligned off the vertical.

The pooling will not stop it working entirely but will reduce the area of cooled copper for the vapour to condense on and change the vapour flow. So reduced efficiency. It will also mean you have liquid retention inside the condenser after you have finished. You could tilt it down to drain it afterwards.

You may find that even at less than optimal configuration the design is still efficient because of the degree of turbulence and vapour/wall contact it generates. By all means try it both ways and report back. I have no ethanol experience so your input would be invaluable.

[Capt-Cudellez]

BTW, when running with the VM column, I use the same condenser almost vertical, the slower take off speeds and high proof need much less cooling than when running fast on a pot.

[ant]

Yes speed of take off and temps are important. Exactly why ethanol could involve different results than methanol that boils at 65deg.

Even so I suspect you could run both heads with a vertical condenser of this design. Of course I could be wrong. I will find out after I build a column. Be quicker if you built a condenser though

[ant]

For what it's worth I checked up on the capacity of the GLPD condensing methanol. One foot of condenser is sufficient for 1kw of heat input. How does that stack against the straight liebig?

[StillWaters]

Has anyone tried this design? I am considering a new Liebig and the concept looks good, but would like someone to confirm this please. Cheers, SW

[YHB]

I have just put a vertical 1 metere 22/15 version of these on the VM take off that I am adding t my Bokakob, it will be a couple of weeks before I try it out but I have no doubt that it will do everything it is supposed to.

[StillWaters]

Thanks YHB, can you tell me the best way to connect SS tube to copper tube? Will silver solder (lead-free) do the trick?? Thanks SW

[YHB]

Sorry, I have no personal experience of this one but I have seen many people asking the same question and cannot remember seeing a good answer.

Yes you can solder stainless to copper, getting the right flux seems to be the hard part. I know there quite a few tutorials on U-Tube. I am have problems with my flash player at the moment so I cant give you a direct link to one.

You could allways use one of these http://www.stilldragon.com/copper-to-st ... ctors.html

or alternativly

Solder a copper fitting with a threaded end to the copper pipe, and weld a matching stainless threaded fitting to the stainless pipe.

Just got my flash player working - have a look at this one http://www.youtube.com/watch?v=suvkKuEURww

[StillWaters]

Thanks YHB. Have determined that a 15mm to 10mm compression reducer is the best way to go. Gives me a bit more strength on the join and no messy soldering/brazing - I'm pretty lethal with flame throwers!!
Cheers, SW