Got some WVO that's titrating high, about 8.5. So I'm thinking about adding some of the glycerine from my last batch (which actually was my 1st batch ever. Yes. Thank you. Thank you).
My questions are:
1) The glycerine from the last batch is now solidified, will it still work?
2) Even if you used wet glycerine, after you mix it up and let it settle, how do you know when the glycerine is through draining out the bottom of the processor and the oil starts? They're both blackish.
3) Does glycerine turn solid because the meth escapes? I kept it in a jug w/ a cap.
Thanks in advance.
1) I would melt it with a little heat.
2) Do the prewash in a drum, not your processor, then take the good WVO from the top. Why is your glycerin wet?
3) There is not much methanol escaping from the glycerin when at room temperature. It can escape when the glycerin is hot.
Like Rick said. Heat.
You could put your glycerin in a 55 gallon drum outside in the sun or you could heat your oil first and then pump the oil into the drum where your glycerin resides. Stir it up with a canoe paddle until it melts and then proceed back to the processor where you mix for about an hour and then send the oil back out to the 55 gallon drum to settle.
I have a standpipe in my drum so I can pull the oil out 8 inches from the bottom of the tank. That leaves a little oil still in the mix, but you can easily recover that for the next batch.
In my experience, when I remove the used glycerin, it is fairly solid. Another good reason for the drum being outside -- it makes it easier to clean up after pretreating.
You will be very happy when you start pre-treating with your old glycerin. Nothing but good comes from it. Your titration value will lower (sometimes considerably), moisture in your WVO will be reduced considerably (if present), and the above results in lower amounts of materials used.
As Rick mentioned, heating it helps, but I also had some pretty solid glycerin that I was able to mix up pretty good with a stout mixing rod. Some lumps in it won't matter. I don't like to make this any harder than necessary and transferring back and forth makes it tougher. So, into the processor it goes!!! I don't dump mine into the processor until my WVO is up around 120* F. The heat will help complete the dissolving problem. Then mix for 1-2 hours, shut down the processor and drain the glycerin off after an hour or so. NOT MUCH LONGER than that as it becomes more difficult to tell when you've crossed layers. I've actually even had to remix mine twice when I couldn't tell where to stop. The glcerin is much darker for some reason after the second mixing and you won't have any trouble telling when to stop draining. However, draining after the first mixing is pretty easy. The trick is to not wait too long. No more than 1-2 hours tops.
You should have MORE stock in your processor than when you started after the pretreatment. I do 30 gallon batches and after pretreating I have 30.5 to 31.5 gallons to process.
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Ive been readding a lot of post on glycerine pretreatment and wanted to ask a few questions,
can you use demethed glycerine?
whats the ratio of oil to glycerine?
what have you experienced in titration readings?
This would help a lot!! Im gettin bad oil that titrates at 7 to 12 with NaOH and dont want to jump into Acid esterification, hopefully the glycerine pretreatment is all i need, at least for now. And i am demething my glycerine and getting 25 maybe 30% of recovered methanol, soo if using un glycerol for the pretreatment gets me more oil and lowers my methanol usage, that would be great!!! tahnsk for the help!!!
You could use demethed glyc. It may not be quite as effective and glyc with the meth in it depending if you are looking at it cleaning the oil, de watering it or lowering titration.
You can use any ratio of glyc. The more you use the better actually because there are more leftover chemicals to work on the raw oil. In practice you will effectively use whatever you had from your last batch but if you got hold of some glyc from a friend, no reason you couldn't use 2 parts glyc to 1 part oil! I'm sure you would see some lowering of the titration then!
I have done this and got up to 4 points lower titration but it depends a lot on how much chem was used in the first pace and what your ration is. A friend was getting oil that seemed very nice and clean except it titrated at 9. He used to circulate the last batch of glyc with the oil for 2 hours, let it sit overnight where he drained the glyc and would usually get the oil down to a titration of 4! It made the difference between good oil and not really worthwhile.
This is very promissing and excitting!!!!! cant wait to try it out!!! looking forward to 85 to 95 percent yields, Thanks DCS, I had read a couple of threads on the subject but noting like fresh first hand info, thanks , i'll keep on posting
Let me start by saying most of my oil titrates at 1-3 so pretreating for me isn't really necessary. But I have a few questions still. Do you still use the same amount(20-22%) of methanol when you process the oil? If not, what is the advantage of pretreating since methanol is the biggest expense in making bio? Is it just to lower your titration level? It also seems that pretreating will add and extra day or so to reaching the end product? That is probably the biggest reason I don't pretreat. Thanks in advance for you responses.
My oil also rarely titrates above 4.0,but I always pretreat to condition the feed stock-the transformation is amazing(I do no other dewatering)For processing I use 18% methanol-my glyc is not demethed.
Overall I consider the pretreat worth the extra days processing,and it helps me recover some meth and bio from the glyc.
Of late, I have been using last batch by product to pretreat my next batch of wvo, I have been so surprised and delighted at the results, oil which normally titrated at 4.6/5.6 showed drops in titration to as low as .8 which saved a considerable amount of catalyst.
It also helps to de water your oil, if you use KoH you will find that as the by product stays liquid it is much easier to use than NaoH. I usually add 15% by product in, which is the glycerol from the first stage of my 2 stage 75/25 reaction. By adding a set amount you know how much you can expect to take out, if a little is left behind it wont make any difference and will come out with your first drain off.
I was inspired to use the 2stage method by watching a series of youtube videos, there are 13 in the series which take you through the whole process start to finish here is the link: Eco2tecthat will take you to the 1st in the series then follow the links
By using the glycerol pretreatment and the 2 stage reaction it has improved my production times and quality
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There's one thing about Glycerol pre-treatment that no one has mentioned, partial conversion.
You have WVO and Glycerol containing methanol and all the base caustic, the ingredients for making Bio.
After a glyc per-wash you need to measure the percentage of conversion, I'm get a consistant 20%. The easiest way to find out is to put 10ml of the wvo into 90ml of methanol, yes a larger 3/27 test, read off the ml of drop out and multiply by 10 to give you the precentage of unconverted wvo.
If you have 8.5ml of dropout you have a 15% convesion so make up you methoxide for the remaining 85%. Apart from reducing the titration, thus caustic, the partial conversion further reduces the quantity of caustic and methanol, it also reduces soaps upping the yeild.
There is no partial conversion unless you add NaOH to the glycerin, or unless the oil titrated very low to start with.
Remember the fastest reaction is the neutralization of acids and bases. The caustic is completely used up before any biodiesel is created.
What you are noticing is the biodiesel that was trapped in the glycerin being released into the WVO.
The benefits of the pretreatment are:
1) lowering the titration number slightly
2) Drying the oil
3) bleaching the oil (trash removal)
4) adding biodiesel to the wvo which has an effect similar to AAF
5) transfers some methanol from glycerin to wvo
Before you assume your making biodiesel, measure the volume, mass and SG of your oil before and after a pretreatment. I think you'll find that enough has changed that you will no longer say a conversion is taking place.
I agree with most of what you say Rick but how do you account for the 80% drop out in a Warnqvist test? If no conversion was taking place surely I'd have a 100% drop out.
I make up my methoxide for the remaining 80% wvo and get a superb 3/27 result, if I reduce the methoxide by 20% in a standard conversion I wouldn't get a 3/27 pass.
Try the test for yourself and explain the missing WVO, as you know WVO is not soluble in methanol but Bio is.
I can not see any reason to think that both reactions (making soap and methyl esters) can not be running simultaneously.
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I completely understand. There have been many reports of having more oil after the treatment than was there in the beginning. Raw Glycerin has a substantial amount of biodiesel in it. The biodiesel would much rather be in the WVO than in the Glycerin/methanol/soap mix. It also drags some methanol with the biodiesel into the WVO. For every ml reduction in titration, you convert 7g/liter of FFA to soap, that winds up in the Glycerin/methanol/soap mix.
I don't know the answer to this, but does FFA dissolve into methanol?
OK we take out some ffa, we add some biodiesel and methanol, we also take out some water. That could easily account for the 80% dropout.
You and a few others may also have some conversion taking place. The process will typically reduce titration numbers 1-3 ml. If it reduces your titration to near 0, then yes, you get some conversion taking place. I think I remember reading that you processed with low titration oil, like around 1. So it IS possible that you are getting some conversion as well as the re-blending of the wvo.
Now that I think of it, Yes FFA does dissolve into methanol. It will not fall out with the WVO. I don't think you would notice the missing fallout until %FFA got above 10% or so.
Wouldn't the FFA take the catalyst for soap before the transesterfication was complete? Then the dropout is most likely to be tri, mono, di, glicerides?
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