On Mon, 09 Sep 2013 16:22:51 +0800, Scromlette
wrote:

It's got some minor metal work involved, but unfortunately no guns or
politics.....

I use quite a bit of methylated spirits to clean electronic PCBs as part
of a cottage business I run. The solvent becomes laden with dissolved
rosin flux & has to be discarded so I've been thinking about distilling
it for reuse. It's costing me 3 or 4 dollars per litre.


I was toying with the idea of electrically heating an old pressure
cooker vented through either a copper coil or an old refrigerator heat
exchanger. I'm not sure if draping wet cloth on the heat exchanger would
be sufficient cooling.

I think the BP of the methylated spirits is ~ 82 Celsius (180F).
Has anyone any experience doing this sort of thing (moonshine perhaps?)

Will it be worth the effort?
I don't know if it will be worth your effort but you can distill your
alcohol without boiling it. This is probably the best way for your
safety. If you heat the dirty alcohol to even 100 degrees F it will
evaporate fairly quickly and it will have less water in it if you are
not using a reflux still. The dirty stuff you have will have absorbed
water from the air. The best you can hope for when the stuff is
distilled will be 95% alcohol and 5% water. This is the azeotrope of
ethyl alcohol and water. For experimenting you can use an aquarium
heater that you submerge in the dirty alcohol. This will give you a
thermostatically controlled heat source that will be unlikely to
overheat and start a fire. Wrap some insulation around the heated
dirty alcohol container and run your copper tubing through a cold
water bath. If doing this in the USA it may be illegal.
Eric