Hello Paul >----- Original Message ----- >From: Keith Addison <[EMAIL PROTECTED]> >To: <biofuels-biz@yahoogroups.com> >Sent: Wednesday, September 25, 2002 11:02 AM >Subject: [biofuels-biz] Fwd: [Biodiesel] Re: liquid glycerine? > > > > Pardon me, but this below is crap, is it not? It's the fatty acid > > portion that's saturated or unsaturated, not the glycerine portion. > > Or could this be the result of poor processing and an incomplete > > reaction? > > > > Thanks! > > > > Keith > > > > > > >Just as important as the amount of FFA's is what the oil actually is > > >made from. If the oil is normally solid at room temp such as tallow, > > >the glycerine will go solid much quicker than glycerine from oil that > > >is normally liquid at room temp such as canola. > > > > > >Even if it is new oil in both cases. > > > >Keith >My experience with a variety of feedstocks bears out the above statement. >Just made some BD from used tallow which titrated at 2ml 1% NaOH. Low >acidity and the glycerine still set solid by the next day. >A mixture of the same tallow plus soy oil plus hydrogenated vegetable oil >gave glycerine which was liquid the next day . >The saturation would as you say be related to the fatty acid portion of the >molecule. The tendency to solidify could have something to do with the >increased chain length of the tallow giving rise to higher melting point >byproduct contaminants in the glycerine. But this is only a guess. >As Todd posted high FFA WVO/WAF need a higher level of NaOH to neutralise >them resulting in increased soap levels. >A comparison of glycerines from both the acid/base method and the single >stage base method (from same High FFA feedstock) would indicate whether the >FFA neutralisation by NaOH led to solidification of the glycerine. > >Regards, Paul Gobert.
I don't think it's so simple. First, he's talking of "glycerine" when what he means is the glycerine layer, which is not just glycerine. The glycerine itself will not be affected. Todd and Michael have posted some good info. I think we can conclude, almost, that whether the glycerine layer solidifies or not depends on the amount of saponified FFAs present as well as which FAs they're derived from and whether they're saturated or not. I said almost because there do seem to be other factors at work. I recently processed some pure lard (pig fat), fresh, unused. Low titration, so I used 4.5 gm/litre oil and 25% methanol, nice split, good separation; then I reprocessed it with another 1gm/litre and 5% methanol to see if any more glyc separated out. None did, but the glyc layer solidified. Then I did another batch with 4.5 gm/litre oil and 25% methanol, no extra, and the glyc layer didn't solidify. So either the amount of NaOH or the amount of alcohol, or both, make a difference. Probably more to do with the methanol - it's been said that if you recover the methanol before separating the glyc layer from the biodiesel it's more difficult to neutralize and separate the glyc layer, I imagine because it's more likely to solidify. Can anyone confirm that? >A comparison of glycerines from both the acid/base method and the single >stage base method (from same High FFA feedstock) would indicate whether the >FFA neutralisation by NaOH led to solidification of the glycerine. I haven't made a comparison, but I'm sure it would, there's a lot less saponified FFA with the acid/base method. regards Keith ------------------------ Yahoo! Groups Sponsor ---------------------~--> Sell a Home with Ease! http://us.click.yahoo.com/SrPZMC/kTmEAA/MVfIAA/9bTolB/TM ---------------------------------------------------------------------~-> Biofuels at Journey to Forever http://journeytoforever.org/biofuel.html Biofuel at WebConX http://www.webconx.dns2go.com/2000/biofuel/biofuel.htm List messages are archived at the Info-Archive at NNYTech: http://archive.nnytech.net/ To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
