Hello Joe. There were probably small amounts of mono- and diglycerides left in the biodiesel, and/or possibly soaps which together are excellent emulsifiers. A strong acid will divide the glycerides into fatty acids and glycerine ,and the soaps into salts and fatty acids, which then goes into a fat phanse and an aquaeus phase, possibly with the salts in the bottom.' Best regards Jan ----- Original Message ----- From: Joe Street To: biofuel@sustainablelists.org Sent: Friday, August 10, 2007 3:45 PM Subject: Re: [Biofuel] Glycerine Settling Time
Hi Jan; Ok your post agrees with what Andres said. So how do we explain Tom's experiment then? To recap (Tom correct me if I miss something here) he took washed esters that passed the methanol test and added water and (of course) no emulsion when agitated. Whatever mono and diglycerides were in the esters were small but present I assume, but yet no emusion. Then added some small quantity of glycerol ( which had been separated from the soaps, FFA and salts) and agitated again and did get an emulsion. I have had the feeling glycerin has usually been the cause of emulsion problems when I have had them. No doubt a poorly reacted batch is much more likely to have the problem but is that really due to the glycerides or is it glycerin which hasn't settled. Remember we started this discussion that the glycerin settles much slower in a poorly completed run. BTW as an addition to this discussion look what someone just posted on my yahoo group! Using glycerin cocktail to BREAK an emulsion. Now that's radical!!?? http://www.biodieselcommunity.org/breakingemulsions/ Joe Jan Warnqvist wrote: 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/ ------------------------------------------------------------------------------ _______________________________________________ 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/
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