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Hmmm, interesting, your first wbd batch soap was very close to mine.
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It's probably my description not being too clear, so you probably got some reversal there then Jon as took 500ml too much, 12.5 litres needed + 9.5 Recoverable = 22% start amount.
If we take the average stoich amount for the majority of oils/fats as 12.5%, then we can recover anything over and above that amount without taking what is needed for the bio, the guide shows what the stoich amount is for the batch size when using 22% methanol, the other column is what you can safely recover, going further can cause reverse reaction, most like to stop 500ml or so short and bubble off any residual meth once the glyc is drained to be safe. Since getting such good purity methanol back I now use 25% methanol as it's easier to work out the recoverable amount being just under half. ************************* 1996 Transit Tipper 1991 Mercedes 709D 1994 Citroen ZX 1.9TD engine now in peugeot 306D ************************* http://www.biofuel-uk.net/ The Collaborative Biodiesel Tutorial http://www.biodieselcommunity.org |
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Fab, You fuge for 12-16 hours continuously? I guess since you're not pulling out soap but rather particulate matter, the heat isn't a concern?? Please expand on this conundrum... |
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As far as yield... my yield went down. However I will disclose that I used a base/base 2 stage reaction and the WVO wasn't dewatered to make sure it was bone dry. That could be why I lost yield if some of the oil and trace water combined with lye to make soap and caused the first round failure of the 3/27 test.
Dewatering has become something that I think is out of reach for me using a water heater. One of my upgrades when I build processor 2.0 will be a cone bottom tank which will allow for heat and settling and draining the bottom of the batch prior to reaction. I had a big soapy mess in the tank that I transferred the batch to. Somewhere between the transfer and completing the 3hr circulation to drive off trace methanol, a BUNCH of soap landed at the bottom of the barrel. All in all I think I converted 26 gallons of WVO into 22 gallons of biodiesel. I feel like I'm playing in the little league sandbox with these small batches. |
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TeePee,
Just my 2 cents and I have not done this yet but I would think if you want to do a 80/20 base/base recipe then you should do what others do with the 5 % prewash... after you pass your 3/27 add all the 1st stage glycerin back in then do your WBD as everyone else is doing.. once added back I would think it would be the same as if you had done 1 stage and never drained.. Just a thought  Lisa 2006 Ford F250 6.0L Powerstroke with 12 inch lift |
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Just curious. What's the point of doing an 80/20 split anyway if you plan on reclaiming the majority of unused methanol? I thought the split was to try to get methanol amount down but reclaiming it all defeats the purpose of trimming methanol from the process.
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some still process with the normal amounts of methanol and koh.. the purpose is simply because you get an easier much better conversion. When you use 22%meth and normal koh it is so easy. If I could reclaim my methanol I would definitly use 22% meth on a base/bsae recipe. I only use less to save money.. Lisa 2006 Ford F250 6.0L Powerstroke with 12 inch lift |
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The glycerine in the batch causes an equilibirum a little higher than 80% conversion. Also when it gets to a point so much of the methanol just dissolves in to the glycerine. By draining it off then reacting again the concentration of reactants to products is again high leading to higher and faster conversion.. as the reaction goes two way, removal of the glycerine prevents it going the wrong way
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thanks Reece.. now I know more! Lisa 2006 Ford F250 6.0L Powerstroke with 12 inch lift |
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Goes to show the difference between understanding and observation. They do not always agree. One or the other needs adjusting. Usually the understanding gets adjusted, unless the observation was a measuring error. 
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No, when drying oil the heat is something you want, I heat to 170 degrees when I'm drying/cleaning oil. |
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DOH!  Well I guess I screwed that up eh! Not much point in doing the phlip now as I have exceeded the recoverable amount... I am not to keen on trying this again as its just too easy to add the acid and not have to worry about the stoich... That being said the more I think I am understanding what this stoich represents the more I am thinking it is probably just as important to not exceed it even when using acid to neutralize the caustic? Does anyone know if the bio will back react with glycerin without the caustic involved? Where can I do more reading to help me understand the stoichiometric situation?  Jon |
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Hey Jon, I made up this excel spreadsheet a while ago based on my WVO. Its typical canola/corn blended cooking oil. Also these calcs were based on the assumption of 100% conversion in one reaction. I agree, it seems much easier and safer to neutrolize catalyst first stoic.xls (19 KB, 31 downloads) |
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I guess I need to get a bit more edumacation on stoichiometrics too. I can't even spell the word.
 I had no idea that different oils would consume different amounts of methanol upon conversion. I guess it makes sense though. Jon,
I guess anything is possible, but the whole idea of the push/pull using acid was to prevent back reactions from happening. I don't see how it is possible for the homebrewer. You might as well give it another try, since you have the testing kits. Just stop short of recovering too much methanol. I would do it if I had my recovery system together. I just can't seem to get motivated.  |
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Hey I just emptied my reaction vessel and performed a much more accurate measurement on the recovered methanol, if it was any closer to 9.5L it would be off! So the experiment is still on! Reece, Thanks for the spreadsheet but I am afraid that I need to do some more research before I could even pretend to know what is going on with it!  Eurocab,
Which part? the neutralizing? If so why dont you think its possible? Jon |
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haha unless you do spreadsheets yourself i agree its hard to follow others workings..
basically i calced I use 11.9L of the 20L I use. Just made it up so i could approximate how much meth i could recover from my glycerine and biodiesel |
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I can program you an app in C++ or assembly but my experience with excel could be written out on the head of a pin!Where did you get the values or the formula to calculate this? I learned more than I cared to know about the definition of stoichiometry HERE but I am still not sure how one would calculate it for our application or better yet what to punch into your spreadsheet to get what I need... Jon Yesterday I couldn't spell chemist and now I are one... LOL |
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member 2009 Sponsor |
After reading this I had to open the xcel sheet, even though I'm on dial up. Reese, I totally agree it's very difficult to understand if your not the one that created it. I work with excel everyday and still don't know where to start. Don't worry though, I created one a couple years ago that I doubt anyone but me would understand. I created mine with a cell to input the starting titration and oil type that would give me everything from the amount of acid to use in an esterification to the base and methanol qty in Neutrals base/ base formula. Then that computer died and I have yet to recreate the sheet. It looks like a good one though, if you understand it. |
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