Dear Keith, > Actually I did understand this, having checked it > out a bit and > discussed it with a few people, but I understand it > even better now - > thanks! What puzzled me and mainly why I asked was > what you said > about methanol excesses. For the whole process, > Aleks uses rather > less methanol than you'd probably have to use for > high-ffa feedstock > by most other methods, especially single-stage base. > Overall methanol > use, not just for the esterification first stage, is > about 67% > excess, depending on the oil; your 9 to 12 times > applies to the first > stage only. Well, that's all clear now.
Sorry if I mislead you in any way. > By the way, there are tables showing the > stoichiometric ratios for > different oils here: > http://journeytoforever.org/biodiesel_meth.html > How much methanol? > > Re the condenser, that's one way, but it's hard to > separate the > glycerine/FFAs/catalyst in the glycerine layer with > the methanol > already removed. Maybe a better way is to drain off > the glycerine > layer first, then evaporate off the excess methanol > in the biodiesel > (it's about half-half in the biodiesel and the > glycerine layer). We do indeed drain the glycerol from the biodiesel in the reactor and we have even tried doing this while the reaction is proceeeding as suggested by Aleks. Theoretically, the removal of a product should push the reaction to produce more product (Le Chatelier's Principle) but we have not yet measured any benefits. > After separating the glycerine layer > (http://journeytoforever.org/biodiesel_glycsep.html), > the rest of the > excess methanol can be recovered from the purified > glycerine > (somewhat purified glycerine). At present, we are setting the glycerol in trays and using it as a soap and general grease remover around the workshop. However . . . . one day . . . > I'd appreciate a picture and diagrams, if that's not > too much trouble, thanks. Our Internet link is really running slowly at present with many disconnections. I will try over the weekend when traffic is less. > So you are using the acid-base process as your main > method, with both > the 100-l and the 1-tonne reactors? No. The 1 tonne reactor continues to use the base-catalysed transesterification of molten stearine/palmitin. The FFA of this feedstock is quite low (less than 1%). We are exploring the acid-base process with HiFFA feedstocks in the smaller reactor and in the laboratory. We know that the process of refining the crude palm oil reduces the FFA to <0.5% by a process of saponification using an almost stoichiometric amount of sodium hydroxide dissolved in water. But the resultant soap is largely a waste material. Some of our crude palm oil comes in at 10%FFA and the saponification process produces rather a lot of greasy soap from such a feedstock. Even the palm-oil refiners don't like this stuff (which is, of course, why it easily procurable!) By adjusting the temperature, we can remove this soap from the bottom of the saponification reactor rather than skimming it off the top but we still lose too much oil to make it an attractive option. Using Alek's acid-base process on such a feedstock has the potential to replace this useless soap with methyl ester. But it appears that any ester actually formed with the acid catalyst is subsequently broken down and saponified along with the palm oil in the base-catalysed second reaction. The result is a spongy mass of soap which is hard to separate from any methyl ester which may have been formed. The main culprit is, I believe, the water which was formed in the saponification process. (But I could be wrong) We haven't given up entirely on the 10% FFA feedstock but we are going to concentrate our immediate research on the more usual and widely available 5% FFA crude palm oil. >Some people have > been having > trouble using it with crude palm oil > (high FFA and high percentage of stearin), but not > with olein palm oil. We are "some people"!! But we find that olein goes like a dream! We have even put together a simple powered-roller reactor which mixes the methoxide with the olein at ambient temperature (30 degC) and takes less than 15 minutes to form the ester. You can even shake them together manually. But we haven't tried olein with HiFFA (yet). Any ideas would be welcome Regards Michael Allen __________________________________________________ Do You Yahoo!? Yahoo! Finance - Get real-time stock quotes http://finance.yahoo.com ------------------------ Yahoo! Groups Sponsor ---------------------~--> 4 DVDs Free +s&p Join Now http://us.click.yahoo.com/pt6YBB/NXiEAA/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/
