ReZn0r, All chemical reactions, in one way shape or form, are reactions of equilibrium. And the results of many reactions are less than desired if the chemical balance is only one of stoichiometric balance. Hence the need on many occasions to use excess amounts of one chemical or another in an equation to drive the reaction in the direction desired.
Relative to allowing enough time for the glycerol cocktail (glycerin, methanol, excess catalyst and soap) to settle out of the first stage before conducting the second? Without controlled testing to quantify the differences between trials/samples, about all that can be said is that the presence of glycerol will naturally attract some of the methanol (like seeks like), as might whatever fraction of soap is present, possibly preventing an unknown fraction of the methanol from randomly interacting with the unconverted glycerides as it might have normally had the first stage been allowed to settle sufficiently. The same holds true for the catalyst, as some water is generated in a transesterification. This small amount largely settles out with everything else in a base reaction. As the catalyst is hydrophyllic, its first tendency is to gravitate towards water, which in turn will bind up a small portion rather than allowing it to perform its function. All this is done in microscopic amounts and may not amount to any discernible difference between samples that have settled twelve hours or samples that have settled six. There is really only one way to determine whether or not there is any "significant" difference between the two end results. That would be to conduct the testing. On a firsthand note, as we don't use two-stage base processing, opting instead for acid/base processing. As a result, we're not exactly in a position to inform you definitively one way or the other. It's also rather doubtful that very many people are in such a position, if only for the reason that it would take some rather controlled experimentation and the majority probably don't have the time or facilities to conduct such testing. On the other hand, it shouldn't be too terribly difficult to conduct some basic/crude testing at your own leisure to see if you can discern any noticeable difference. A fair guess is that you wouldn't notice much, if any. Perhaps what another question might be is "Do you really have need of expediting a process?" If so, such as in an industrial/commercial environment, testing might hold more validity for you than other bears of average brain. Todd Swearingen >Hi Appal, > >Con fecha miércoles, 14 de diciembre de 2005, 14:00:32, escribiste: > > > >>>Hi >>> We are making BD with a homemade reactor (80 liters). We have used de >>> single stage and de two stage (base-base) methods succesfuly, but we still >>> having many doubts :) >>> >>> > > > >>> In the two stages method described in journeytoforever, the mix >>> settle around 12 h between first and second stage before extract the >>> glycerine. It?s necessary to settle so many time? It?s bad if any glycerine >>> is not decanted and is mixed in the second stage? Is there any "trick" to >>> avoid to wait 12 h between first and second stage? >>> >>> > > > >>>Many thx in advance and sorry for my bad english >>> >>> > > > >>> >>> >>> > > >AE> ReZn0r, > >AE> "Settling time" is simply letting gravity do the separation work for >AE> you, rather than enlisting equipment such as centrifuges. The more >AE> glycerol/soap that is extracted by settling the less impediment to the >AE> subsequent step, whether it be stage two or washing. > >AE> Todd Swearingen >Hi Todd > >Thx for reply > >I Agree with this and for sure is very important to let settle before wash, >but I want to know if is there any problem in the second stage if we have 5% >for example of total glycerine from the first stage inside the mix of the >second one... (I think 95% of glycerine settles in less than 1 hour, correct >me if I am wrong) > >AE> _______________________________________________ >AE> Biofuel mailing list >AE> Biofuel@sustainablelists.org >AE> http://sustainablelists.org/mailman/listinfo/biofuel_sustainablelists.org > >AE> Biofuel at Journey to Forever: >AE> http://journeytoforever.org/biofuel.html > >AE> Search the combined Biofuel and Biofuels-biz list archives (50,000 >messages): >AE> 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/
