Hi evereybody. I feel obliged to enter this discussion. Pure glycerine is not a good emulsifier due to the fact that there are three OH-groups and that the carbon s in the first and third positions are surronded by two hydrogene atoms. This makes the glycerine hydrophilic in five places alltogether. However, the mono- and diglycerides are excellent emulsifiers. Only small amounts of these are sufficient to create stable emulsions. Would somebody agree with me on that ?
Jan Warnqvist ----- Original Message ----- From: "Keith Addison" <[EMAIL PROTECTED]> To: <biofuel@sustainablelists.org> Sent: Friday, August 10, 2007 9:53 AM Subject: Re: [Biofuel] Glycerine Settling Time > Hi Tom > >>Hi Keith, >> >> > Then if you do one-litre test batches first, especially with iffy >> > batches of oil, >> >>Ooooops. >> >> I took Joe's point to be: If you have to re-process it is possible to >>use info from the QT to determine how much (how little) methanol you'll >>need >>to use. > > I also took that point, there were others though. It's a useful > method, cheaper reprocessing, but I think we all agree that > reprocessing itself is to be avoided if at all possible. Or I thought > we did anyway. > >> I think that both Joe and myself have "standardize(d) the process" >>so that passing the QT is the rule, not the exception. > > That's not what Joe said: > >> >>It makes sense. Glycerin is an emulsifier. Have you ever tried >> >>dosing the batch again with a little methoxide? After you remove >> >>the glycerin it doesn't take much to get the last bit of the >> >>reaction to go and settle out the remaining glycerin. Of course >> >>this is well known already. Kenji and many others do straight base >> >>catalysis as a two stage deal. You can do a methanol test of sorts >> >>and the unreacted oil will settle out. Then you can use the >> >>measured amount of unreacted oil in the methanol test vial to >> >>estimate the percentage unreacted oil in your batch and dose >> >>accordingly with the stoichiometric amount of methoxide. Assume >> >>neutral oil for this calculation. Rod and I do this regularly if >> >>the batch fails the QT and it works like a charm. Will save you >> >>settling time in the long run. > > "Rod and I do this regularly if the batch fails the QT and it works > like a charm." That "if" makes it a little ambiguous, but the > "regularly" bit puts a question-mark on what's the rule and what's > the exception. > > "Kenji and many others do straight base catalysis as a two stage deal." > > Less methanol notwithstanding, my question remains - why reprocess, > as a standard procedure, instead of avoiding the problem in the first > place? > > Could be wrong, but it sounds like Kenji and others might be doing > this rather than doing a titration - you know the old line: "There's > no need for titration, just use 6.25 g". And then using the methanol > test to try to fix the regularly ensuing disaster. A different > version of that here in Japan is to put the stuff through a > centrifuge, though the product still doesn't pass any quality test or > standards test. > > What you describe is much the same as what I described, doing > (whatever) tests during the processing, adjusting accordingly and > conducting the whole thing as a single stage. > > From Joe's replies so far I can't tell if he (and Rod, and Kenji and > many others) are doing it that way or not, but it seems not: > > Your question (and mine): "Don't you have to heat up the whole batch > again? (Time and energy)" > > Joe's reply: "This is all done right after draining the glycerin. I > leave the heater on during this period. Do the rough QT right away > before wash test." > > Rough QT? Anyway, how long is it settling before he drains the glyc? > >> I run a QT towards the end of the reaction because I do not want to >>re-process. > > Indeed not. > >>It takes me a few minutes and I like the certainty of knowing >>the BD is good before I pump it into my settling tank. >> If the test should fail when I'm making a batch for my car, I could >> use >>Joe's suggestion to help me better approximate the amount of methanol to >>add. >> >> If the process has been standardized, why bother? > > I think this is a misunderstanding. I didn't say what you say below, > "standardized; can't fail", and I didn't mean that standardising the > process means there's no need for tests, whether in-process tests or > 1-litre test batches or whatever. Anything can fail. I'm all in > favour of any tests that are helpful at any stage. So I agree with > all you say here. > > Indeed, whatever "rough" might mean, using the methanol test to > fine-tune the amount of extra methanol needed for reprocessing is a > useful technique. > > But I'm not in favour of using reprocessing as a standard method, > which, pending a better explanation, seems to be what's being > proposed here. > >>As you say: >> >> >there shouldn't be any batches failing the QT. >> >> I've had a few failed batches in the past year. It seems to happen >> when >>I think I have it all figured out; standardized; can't fail. On one >>occasion >>the pump was making a bit of a "funny" noise when I came back to turn it >>off. Turned out a bit of paper towel or something had gotten into the >>impeller; inadequate agitation? Had I tested the BD before pumping it into >>the settling tank I could have avoided re-processing. >> While condensed water in bottom-of-the-barrel methanol or recovered >>methanol, contaminated caustic, etc may rear their ugly head in 1L test >>batches prior to running a batch, I think I would still run a QT prior to >>settling. >> >> >>Big skies >> > >> > :-) And broad horizons. >> >>Big lunch to you, >>I just had a garden pizza with Brocolli, zucchini, green peppers, sliced >>tomato, and chopped (v. mild) hot peppers. >> >> >>Mmmmm Mmmmmm Mmmmmm > > :-) Great Tom! A big lunch definitely helps when it comes to broad > horizons. But quite often it's quicker just to amble on out and eat a > bit of garden in the meantime, and pin one's hopes on a big dinner. > On the other hand, I think there just might be some poached Muscovy > egg and stir-fried Swiss chard in the offing... Man, it's going to be > hard ever to go back to the city life. > > All best > > Keith > > >> Tom >> >>----- Original Message ----- >>From: "Keith Addison" <[EMAIL PROTECTED]> >>To: <biofuel@sustainablelists.org> >>Sent: Thursday, August 09, 2007 3:36 PM >>Subject: Re: [Biofuel] Glycerine Settling Time >> >> >> > Hi Joe >> > >> >>Tom; >> >> >> >>It makes sense. Glycerin is an emulsifier. Have you ever tried >> >>dosing the batch again with a little methoxide? After you remove >> >>the glycerin it doesn't take much to get the last bit of the >> >>reaction to go and settle out the remaining glycerin. Of course >> >>this is well known already. Kenji and many others do straight base >> >>catalysis as a two stage deal. You can do a methanol test of sorts >> >>and the unreacted oil will settle out. Then you can use the >> >>measured amount of unreacted oil in the methanol test vial to >> >>estimate the percentage unreacted oil in your batch and dose >> >>accordingly with the stoichiometric amount of methoxide. Assume >> >>neutral oil for this calculation. Rod and I do this regularly if >> >>the batch fails the QT and it works like a charm. Will save you >> >>settling time in the long run. >> > >> > Well, settling time is free. >> > >> > Acid-base aside, there's the two-stage base-base process, which quite >> > a lot of people use and like, but otherwise why do more than one >> > stage? Do you mean two separate stages, with a methanol test in >> > between? So you process it twice? Plus extra methanol. >> > >> > Why not do it in a single phase? Todd Swearingen once suggested this >> > here (discussing mixing pump sizes): >> > >> >>To judge an appropriate reaction time, pull an exact amount of fluid >> >>(200 ml would suffice) out of the reaction stream every half-hour or >> >>hour after an arbitrary initial ~1 hour reaction period. >> >> >> >>Presuming that the contents of the reactor are kept homogenous from >> >>the pump flow, the volume of the glycerol cocktail that settles out >> >>of each sample will give you a fair gauge as to when your reaction >> >>completed. >> >> >> >>The suggestion would be to continue the reaction for ~1/2 hour >> >>beyond the point where your glyc cocktail volume stabilized. >> > >> > That works. Then, surely, you can standardise the process, with the >> > only variable the amount of lye according to the titration level. >> > Then if you do one-litre test batches first, especially with iffy >> > batches of oil, and you have a clear idea of how your test-batch >> > processing relates to your full-scale processing, life should be >> > easier and there shouldn't be any batches failing the QT. >> > >> > What did I miss? >> > >> >>Big skies >> > >> > :-) And broad horizons. >> > >> > Keith >> > >> > >> > >> >>Joe >> >> >> >>Thomas Kelly wrote: >> >> >> >>>Joe, >> >>> >> >>> I took a sample from my latest batch of BD destined for my >> >>>boiler (failed QT; but very little residue dropped out). It had >> >>>settled for almost 10 hrs. >> >>> That was yesterday morning. Today there is a small, but >> >>>noticable, bit of glycerine on the bottom. More settled out after >> >>>the initial 10 hrs of settling. >> >>> >> >>> I don't have any results with good BD to compare it with. >> >>> >> >>> If it turns out that glycerine settles out slower from >> >>>incomplete vs complete reactions, it would answer the question I >> >>>asked about getting emulsions when I washed low quality BD after >> >>>letting it settle overnight, but not getting emulsions when it >> >>>settled for a few days to a week. >> >>> It would also help with a friendly disagreement I have with a >> >>>friend. He seems to think that unreacted glycerides will settle out >> >>>of the BD given time. He has taken to going with about 16% >> >>>(vol/vol) of methanol in his batches. >> >>>His logic: >> >>> "Unreacted oil causes emulsions, right?" >> >>> "The emulsions I get in the first wash after settling the >> >>>BD overnight are due to the unreacted oil?" >> >>> "When I let it settle for a week or more I don't get >> >>>emulsions, therefore the unreacted oil must have settled out." >> >>> >> >>>More likely: >> >>> Some unreacted glycerides are still there, but after a week of >> >>>settling more of the glycerine has settled out. Even a small amount >> >>>of glycerine compound the emulsifying effects of the unreacted >> >>>glycerides ..... Yes? >> >>> >> >>>By the way, I always ask him "Did you do a quality test?" >> >>> His answer: "Oops, I forgot." >> >>> >> >>> Thanks Joe .... and Rod ..... for bringing this to my attention >> >>> A push to make a lot of BD for heat is just around the corner. >> >>>It might be best to include more settling time in the schedule. >> >>> >> >>>Tom >> >>> >> >>> >> >>> >> >>>----- Original Message ----- >> >>>From: <mailto:[EMAIL PROTECTED]>Joe Street >> >>>To: <mailto:biofuel@sustainablelists.org>biofuel@sustainablelists.org >> >>>Sent: Tuesday, August 07, 2007 3:02 PM >> >>>Subject: Re: [Biofuel] Biofuel Quality Test >> >>> >> >>>Hey Tom; >> >>> >> >>>Take a sample from your fuel after settling 6-8 hrs and set it >> >>>asside in a mason jar for the longer period and see what settles >> >>>out. Rod believes that glycerin settles slower in a poorly >> >>>completed reaction. I believe he is right. And yes it only takes >> >>>a little glycerin to emulsify your wash. >> >>> >> >>>Joe >> >>> >> >>>Thomas Kelly wrote: >> >>> >> >>>>Mike, >> >>>> I let mine settle for a week when I can. It washes much easier. >> >>>> I >> >>>> doubt >> >>>>that it does anything for an incomplete reaction though. That is to >> >>>>say, >> >>>>I >> >>>>don't think the unreacted oil will settle out. >> >>>> >> >>>>But: >> >>>> I have been wondering about something. >> >>>> When I started making BD it would never pass the methanol quality >> >>>> test. >> >>>>I inevitably got emulsions in the wash. Now, when I make BD for my >> >>>>"oil"-fired boiler, I use only about 16-17% (vol/vol) of methanol. >> >>>>The >> >>>>BD >> >>>>does not pass the quality test, but I don't have the same emulsion >> >>>>problems. >> >>>>Is it because I let it settle longer (24+ hours vs 6 - 8 hrs)? >> >>>> Does the presence of a small amount of glycerine/soaps make that >> >>>> much of >> >>>>a difference when trying to wash BD from an incomplete reaction? >> >>>> >> >>>> Tom >> > >> > <snip> > > > _______________________________________________ > 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/ > > > _______________________________________________ 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/
