>I have pondering this for some time but figured I should get some >success with making fuel first. > >Since alcohol is added from time to time to storage tanks so it will >mix with the water and thus the blended alcohol water mixes with the >fuel. > >This being the said, I wondered if the wash could be shortened or >less of a waste problem by distilling the methanol out of the >finished product before washing. > > I have just finished a 120 liter batch I pulled off 1 liter of fuel >stock ΒΈ I put in a old pressure cooker with the steam vent replaced >with a hose barb and connected it to my evaporator. Turned the flame >on and heated to 275 deg F for 10 minutes or so. Let it cool a bit >and pored it into a pet bottle added the wash water shook it hard it >separated in just a few minutes. The other half was just put in a >pet bottle and wash water was added and shook it hard although it is >separating not even close to the same speed as the demethanoled >batch. > >Is there any problem with this process? I wouldn't ask but I can't >find anything in the archives.
There's quite a lot about it in the archives, and more at JtF. Most of the methanol excess ends up in the by-product layer, the rest in the biodiesel (proportions at JtF), and both can/should be reclaimed. Though it's worth reading this too: More about methanol http://journeytoforever.org/biodiesel_make.html#moremeth The methanol in the glyc by-product can be reclaimed as-is, but if you have a use or a market for the separated by-products then separate the glycerine-FFA-catalyst first, and then reclaim the methanol from the glycerine fraction. With the portion in the biodiesel, reclaim before washing. Most convenient would be to reclaim it all at once right at the end of the process before removing the by-product while it's still hot and near the boiling point of methanol, but that throws the reaction into reverse, undoing the work you've just done making the biodiesel. You can reclaim the methanol with a pot-still or equivalent, with either the biodiesel or the by-product. Some people use vacuum too. No need for such high temperatures. The methanol starts to evaporate well before boiling point, but it doesn't really work like that anyway. Roughly speaking, if you make a 50/50 mix of two liquids with different boiling points they don't each boil off at their respective boiling points, the boiling point of the mixture will be about halfway between the two. Then there are complicated things about volatility and so on, but the one with the lower boiling point (ie the methanol) boils off first, and as it boils off the boiling point of the mixture rises until (in theory) there's none left, at the boiling point of the other liquid. With the by-product, you won't get it much above 100 deg C before it starts frothing, you'll have got most of the methanol but not all of it. If you use flash-evaporators you'll get better recovery with less energy input, for both bd and by-product. I think the positive effects on washing of recovering the methanol from the biodiesel first have been discussed, sorry, I don't have the time to pin it down right now. Best Keith >Thanks Derick _______________________________________________ Biofuel mailing list Biofuel@sustainablelists.org http://sustainablelists.org/mailman/listinfo/biofuel_sustainablelists.org Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Search the combined Biofuel and Biofuels-biz list archives (50,000 messages): http://www.mail-archive.com/biofuel@sustainablelists.org/
