I thought that the problem with excess methanol is that it's an atmospheric pollutant- that when we compost glycerol or somehow treat or release any wash water that contains volatile methanol, the methanol evaporates into the atmosphere and does some sort of damage there. I think someone mentioned very recently on this list that the EPA would prosecute homebrewers due to the methanol discharge into the atmosphere (but can't afford to).
mark --- In biofuel@yahoogroups.com, Keith Addison <[EMAIL PROTECTED]> wrote: > Hi again Todd > > As far as the wash-water's concerned, water hyacinths quite happily > eat the first-wash water, methanol and all, clean it up nicely. Well, > actually it's a mix of water hyacinths and two types of duckweed, > about both of which there's much good information to be found at JtF: > http://journeytoforever.org/edu_pond.html#duckweed > http://journeytoforever.org/edu_pond.html#waterhyacinth > > The washwater is innocuous enough, apart from the methanol - no heavy > metals or toxins, for instance, so the plants themselves remain > usable. Both make excellent compost, and that's a satisfactory > solution - not as satisfactory as reusing the excess methanol, but > you are recycling it well. Aslo the plants break the stuff down, > they're not full of methanol and lye, and still make good livestock > feed. > > Best > > Keith > > > >Maud, > > > >I wouldn't consider the MeOH content in the biodiesel to be negligible. Not > >at all. > > > >Unfortunately, many others consider it so. > > > >Simplest method to determine the volume of MeOH that resides in the > >biodiesel and glycerol, as well as the volume that was consumed in reaction, > >is to measure the volumes of alcohol laden biodiesel and glycerol, evaporate > >the MeOH and then measure the remaining volumes of each. > > > >The easiest way, IMNSHO, to determine if the MeOH volume in the biodiesel > >fraction is negligible is to stick one's nose over a container and huff it. > >(Not advised, but the point being made should be easy enough to decipher.) > >Without removing the alcohol you've got a fluid that has a flashpoint > >essentially the same as methanol, rather than the rather safe flashpoint of > >biodiesel. > > > >To test that theory, take a piece of cotton wick, anchor it in a 6 ounce > >metal tomato paste can as if you're going to make a candle. Fill the can > >with MeOH laden biodiesel. Light the wick as if the can were an oil candle. > >Sit back and watch. Everything goes fine for a bit, that is until the fuel > >heats up to the boiling point of alcohol. Then you have a runaway alcohol > >torch. > > > >That's the same alochol that would "normally" get washed down someone's > >drain or flushed out into the back forty. The same stuff that a lot of > >people consider "insignificant." > > > >We haven't yet taken any time to quantify the average volume of MeOH that > >remains in the biodiesel. But it is a safe bet that the ratio is consistent > >between the biodiesel and glycerol fractions no matter how much alcohol is > >originally used. The more alcohol used in the reaction, the more alcohol > >will remain in the biodiesel and end up in the wastewater stream if > >evaporation is not conducted prior. > > > >Most people have probably noticed that MeOH and biodiesel are completely > >miscible in each other in any volume. > > > >If a person is worried about the energy inputs required to recover the > >alcohol from the biodiesel, then they should be looking at insulation, heat > >recovery and renewable fuels for the energy inputs. > > > >Todd Swearingen > > > >----- Original Message ----- > >From: "Maud Essen" <[EMAIL PROTECTED]> > >To: <biofuel@yahoogroups.com> > >Sent: Saturday, December 13, 2003 7:08 PM > >Subject: Re: [biofuel] methanol recovery before separation > > > > > >Todd, is the amount of methanol remaining in the methyl ester > >considered negligible? Is it possible to determine what percentage > >remains in the methyl ester and what percentage in the glycerol? Maud > > > > >Lagonisa, > > > > > >> The problem is > > >> that I have also read that due to the reversibility of the reaction, > > > > > >The reaction is not exactly reversible. "Reversability" would require the > > >three glycerides and the glycerol recombining. That doesn't happen. Once > >the > > >glycerol is cleaved it is out of the picture. > > > > > >You're suggesting MeOH recovery at the point where the reaction is complete > > >and the glycerol has yet to settle out. However, that's not altogether > > >adisable due to the continual mixing of excess catalyst with the methyl > > >ester. > > > > > >If you reduce the volume of alcohol via evaporation at this point there > > >would be a propensity for some of the ester to fracture ("back crack") into > > >FFAs and then convert to soap. Mind you that "back cracking" can only occur > > >up to the point that all the catalyst is consumed in soap making. > > > > > >If you can monitor the reaction and insure that the balance of catalyst is > > >infintesimally small beyond what is required to guarantee 100% completion, > > >erego yielding but a small and controlled amount of extra soap production, > > >then there might be some merit in extracting the alcohol prior to the > > >glycerin cocktail settling. > > > > > >Otherwise? Probably none. > > > > > >Todd Swearingen > > > > > >> Hello to all: > > >> > > >> I have read some contributions to this group about methanol recovery > > >> and the different options. I would like to try the recovery before > > >> separation of bio and glycerol using a condenser that would receive > > >> the methanol fumes after finishing the reaction. I have a processor > > >> were I get 75¼C-80¼C as it is pressurized to 0,7 bar. The problem is > > >> that I have also read that due to the reversibility of the reaction, > > >> if after finishing my reaction I remove the methanol by reducing the > > >> pressure and directing the vapours through a condenser, or even I > > >> apply vacuum after despressurizing to do it faster, I can get a > > >> reduction of the conversion transforming some biodiesel into oil > > >> again. My question is: has anyone in this group measured or > > >> experienced this fact? Is there a real decrease of the yield or > > >> conversion? > > >> > > >> Lagonisa ------------------------ Yahoo! Groups Sponsor ---------------------~--> Buy Ink Cartridges or Refill Kits for your HP, Epson, Canon or Lexmark Printer at MyInks.com. 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