Since I use a 5% prewash, and I recover methanol from the glycerine, won't there be water vapor mixed in with the methanol vapor coming out of the condensor? I tried to find out if this was already addressed in an other post, but could not find it. Do I need to purify it? I condense at 150F. with a little bit of positive pressure.

From my experience with a crude still, I get about 85% purity from the 5% prewash glycerol. More like 93-95% with non-prewash glycerol.

You can get better purity with a reflux column type condenser or you can blend it up with new methanol for re-use.

I have made successful batches with even the 85% purity by adjusting up the quantity some. Only did that once and don’t remember any more soap than usual. Didn’t really quantify the yield either, but it was worth doing!

Good luck,

Bob

How does one measure the purity?

Methanol specific gravity is .793 which means one liter of methanol will weigh 793 grams compared to 1000 grams for water. So, assuming the only other element in the mix is water, it should weigh 207 grams less than water. If it weighs 896.5 (1000 – 896.5 = 103.5) which is ½ way to 100% water then I would call it 50% Methanol.

1000 – S.G. / 207 = % purity

1000 – 896.5 / 207 = 0.50 or 50%
1000 – 825 / 207 = 0.845 or 84.5%

Your hydrometer should measure S.G. in grams for you to figure this way, or you can weigh a 1 liter sample to get the same result.

Bob

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-Jim

I am real close to getting goin, i bought one of the hydrometer shown in the above post and tried it out on some new methanol, it works good.
My question is, if you got 85% methanol recovered, could you freeze any of the water out?
Sounds kinda like a stupid question to even me, so be kind....
Jammer

I thought the same thing yesterday and got all excited for a minute. Then I realized that you add methanol to water to keep it from freezing...it is added to windshield washer fluid in the winter to keep it liquid to a lower temperature.

I still would like to hear if it would separate when you finally did get it cold enough to freeze. Wouldn't that be cool? Scouping ice cubes out of a pool of methanol!

I just don't think it works that way...

-Jim

If you have a still with a reflux/fractioning column you can re-distill your low purity methanol. I've had good results with this.
Easy to build, easy to use.
-mcguyver

mcguyver, got any plans for a reflux column? I did build my condenser per your plans, the question i have is the 1/4 in copper, is that id or od? I used 1/4 od but wondered what you used to attatch to the top of the wh?
Jammer

quote:

mcguyver, got any plans for a reflux column? I did build my condenser per your plans, the question i have is the 1/4 in copper, is that id or od? I used 1/4 od but wondered what you used to attatch to the top of the wh?
Jammer

Hey Jammer,

I've got both a 1/4" ID and OD. Both work fine, the 1/4" ID is easier to build and the 1/4" OD is able to handle a little more volume. The average 50 gallon appleseed will work fine with a 1/4" ID.

On the top of the water heater (from one of the three 3/4" holes) I installed a 3/4" street elbow then I reduced down to a 3/8" ball valve. Out of the 3/8" ball valve I put a fitting that was 3/8 pipe thread on one side and 1/4" compression tubing connecter on the other. Then I have a piece of 1/4" tubing from the ball valve into the top of the condenser. It works great.

It's quite the challenge to bend the 1/4" Id (aka 3/8 OD) that's why you have to use 4" pvc to do so.
dsaAll I have is this rough drawing of the condenser. It's not much but it'll show yo all you need to know.



HTH

-mcguyver