Vapour exits Liebig cooler

[albertvanhulzen]

Hi all,

I'm new at distilling. On the first run (from a plum and sugar fermantation) the driprate was much higher then it is now and no vapour escaped. I'm now doing an second run. If I put my finger on the cooler then pressure builds up. Vapour comes out of the cooler. That would be lost alcoholol. It drips at 60 drops/sec, distillate is could to the touch, thermometer reads 72°C, alcohol is close to 82%. I´m using a pot still made from an 8inch pressure cooker and an 10mm inner diameter Liebig cooler. The cooler is 65cm long. What am I doing wrong?

Albert van Hulzen

[Barney Fife]

You're simply running it too hard for the size of your liebig. Back off on the heat.

[violentblue]

turn up the water flow through your liebig.
also not sure how you have flow setup, but water should enter the cooler at the bottom and exit at the top.
and yes the vapor is escaping alcohol, extinguish all heating sources untill this problem is resolved, or you could have a fire on your hands.

also you could try turning down the power on your boiler slightly.

[rad14701]

You could also try inserting some copper scrubber into the liebig for better thermal transfer...

[violentblue]

You could also try inserting some copper scrubber into the liebig for better thermal transfer...

yup, disrupting/slowing the vapor would definatly help. it'd be more likely to come in contact with the walls of the condensor that way.

[albertvanhulzen]

Thanks for your quick response. A small strip of tissue taped to the end of te cooler was flapping like there was e severe storm. I did indeed find a power setting that doesn't cause the cooler to act as an exhaust. The driprate is three or four seconds/drop now. My grandmother was slow but she was old.
Putting scrubber in the cooler is new to me. I'm goming to try that or make more (parallel) and longer coolers. It seems to make sense to condens what you can evaporate instead of limiting evaporation to the condensers small capacity. Does anyone have experience with multiple coolers?

Albert van Hulzen

[Hack]

I've never used a liebig condenser, but 10 mm seems like an awful small inner diameter. I'm guessing that you are going to have trouble getting a larger flow rate out of that.

[snuffy]

With a rig this small, it will have to run gently. Too much heat will push the vapor through the condenser so fast that it won't have any contact time to shed the heat and condense the vapor.

One of my early stills was only a little bigger than this, but it used a glass condenser. When it was working right, a very visible vapor line formed at the top of the condenser. Turn up the power too much and that line blurred, then vanished and vapor started coming out. It looked like there was a critical speed for the vapor to condense. If if moved faster than that speed, it didn't condense at all. The transition was very sudden and output did not increase before it crossed the threshold and started blowing vapor.

When the vapor speed hits a threshold, the speed of the vapor causes it to pull into the middle of the condenser tube and not contact the walls. It has to touch the cold surface to shed heat. If it doesn't touch, it doesn't get cooled.

The 10mm output line is pretty narrow. Be cautious about putting something in it to increase turbulence (and make it more likely for vapor to contact the cooling surface.) It won't take much liquid to block the output and then it may start "putt-putt-putting." Try a very thin copper wire with just a few kinks in it. It takes very little to cause turbulence.

Even then, the power limit of the condenser is the cold surface area of the tube. 204 sq cm (1 x 65 x pi) is not much area for all that heat to pass through to the cooling water. If your heat source exceeds that, vapor will not get condensed.

There is a calculator on the mother site that figures wattage for condensors: Theory/Interactive design calculations/Condenser size. It indicates your condenser is probably maxed out at around 750 Watts. In practice, it's probably more like 600 Watts.

*edit* PS: You say you are using a pressure cooker. You don't say how big the exit is. It should be a fitting that connects to your 10mm tube. The exit has to be at least as big as your condenser tube or the boiler will pressurize. Most pressure cookers have a very small opening in the vent to the pressure valve. This isn't big enough to work properly.

[rad14701]

*edit* PS: You say you are using a pressure cooker. You don't say how big the exit is. It should be a fitting that connects to your 10mm tube. The exit has to be at least as big as your condenser tube or the boiler will pressurize. Most pressure cookers have a very small opening in the vent to the pressure valve. This isn't big enough to work properly.

Good point, snuffy... If the vapor is moving too fast, due to the small orifice, combined with a small condenser, is going to definitely cause problems... While light packing may help, too much will only result in an increase of vapor speed...

[pHneutral]

Besides backing off the heat, you could use ice cold water in the leibig to remove a bit more heat. Basically, an aquarium pump in a bucket with ice water (plenty of ice) that you top off with ice cubes when you see them melting away too much. It won't help a -lot-, but it could help increase your rate a bit. Plus you're not wasting water

[CoopsOz]

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Why is it that Albert's avatar panel claims he only has one post when he has at least two in this thread alone?

[punkin]

Glitch in the Matrix