Has anyone tried reprocessing the glycerine from the last batch into a new batch to clean the glycerine of the leftover menthoxide and start the reaction process. I have tried this a number of times and it will reduce the titration numbers by about 40%. The glycerine after reprocessing is thick and is tan in color. This may not be the best method to reprocess the glycerine but it is very simple and energy efficient way to eliminate an unwanted byproduct. If anyone has tried this how well do you think the glen is cleaned up and would it be worthwhile to do a GC analysis?

I do it. Don't know if it lowers my numbers any, I only check my first batch pre-glycerol. But then it titrated @ 0.8 after, so it was already good to start with.

I do it also. I have been bringing it up every chance I get. Mostly over in the methanol distillation areas. Since the goal is to recover methanol for use in further batches it seems to be a good fit without being a true thread hijack...

After incorporating the methanol from my raw glycerin I was using the full calculated amount of methanol and NaOH to do the main process. I have now started reducing the amount of methanol & lye that I use in the second (main) process.

I think I will try deducting the amount of incorporated methanol from the calculated amount.
Calculated:
40 gallons of oil
8 gallons of methanol
1200g of NaOH

After incorporation I end up with 6 gallons of glycerin. So about 2 gallons of methanol was incorporated. Based on that, I should only need 6 gallons of methanol and maybe 900g if NaOH. It may end up being too little methanol and/or NaOH. I'll do a 3/27 test to see how it does.

That said, this is something that will have to be measured on each batch. Every time you short the second process you will end up with less excess in the glycerin for incorporation into the next batch.

It still works and is a great way to "recover" your methanol from the glycerin.

-Jim

how long does it take for the glycerine to settle out of the wvo?

Jim D I agree with the idea of what you doing to cal the amount of methoxide remaining in the last batch to be incorporated in the next batch. As you say if this works the next batch will have a reduced amount of methanol to be used . This is the same though that I have but if you look at you math you are using the same amount of methanol on the second batch only part of it is coming from the glycerin. Based on you test data it may show what percentage of methoxide you are getting on the first reclaim process. The data may show that maybe 80% (just a guess) would be the amount that you are reclaiming. It would also help if we could get an analysis on the reprocessed glycerin to see how much methanol is remaining. Have you looked at the difference in the titration numbers before and after the first process of reclaiming the glycerin.This opens up another can of worms when you look at when incorporating the math of adjusting the amount of NaOH and methanol on the second process. This may need to be a discussion for another day. I look forward to seeing how your process works out using the reduced numbers and what the 3/27 test shows. Thanks for the feedback and let us know how you test works out.
Thanks
Rockhot

Hi Rockhot,

The titration number will drop.

I am more interested in using less lye in the batch.

This makes for less soap in the biodiesel.

High conversion low soap biodiesel is the easiest to wash if you water wash. Or just let the soap drop out then drain it using a Canoe Paddle Processor.

You need a drum that will drain all the way like a cone bottom or a tilted drum with a drain on the bottom.

Thanks, Steve

I started a new thread about a new twist on this and the GL1 method. I didn't want to hijack this thread.

http://biodiesel.infopop.cc/eve/forums/a/tpc/f/4441089311/m/6771041932

-Jim

Hi Jim,

Have now mixed in the water and given it a dam good thrashing. Looks like a lovely brew of tea!
Now just waiting.

While i'm waiting another question. Do you just take off your glycerol and keep it in a container till you are ready for the next batch then add it to your new load of WVO? How long can you keep it for? Once you have added previous glycerol to next WVO, mixed, titrated, add methoxide, mix, settle, do you use this next lot of glycerol to treat the next and so on? Do you stop at a percentage of glycerol per litre of WVO?

Regards

Paul

The glycerin that you have added water to is not good for pretreating the WVO in the process listed above. You could still use it to pretreat, but then you would have to remove the water before you do the main process on your oil.

For the other question:

The longer you store the glycerol the more likely it is that the methanol will evaporate off. A tightly sealed steel container may really help prevent this, but it is better to just use it right in the next batch and get it over with. I only use a batch of glycerol once to pretreat. After that the methanol has been sucked out of it and it is done.

-Jim

quote:

Originally posted by Jim D:
The glycerin that you have added water to is not good for pretreating the WVO in the process listed above. You could still use it to pretreat, but then you would have to remove the water before you do the main process on your oil.

For the other question:

The longer you store the glycerol the more likely it is that the methanol will evaporate off. A tightly sealed steel container may really help prevent this, but it is better to just use it right in the next batch and get it over with. I only use a batch of glycerol once to pretreat. After that the methanol has been sucked out of it and it is done.

-Jim

Hi,
If you tried to remove the water you would also remove the methonal and then the whole idea is void.

After you use a batch, the methanol has not been sucked out. The reason you put the "glycerol" into the new batch is because it contains methanol that will substitute for a portion of fresh methanol. You still use the same amount of methanol (hopefully); therefore, you should get approximately the same amount of excess methanol in your by-product no matter what process you use. The only thing different about the by-product from the second batch (pretreated batch) is that you end up with more by-product and thus a lower percentage of methanol. There is more by-product because you still get the fresh by-product plus the added previous by-product. Right?

I tried this for the first time last night. Cut my titration in half. I am wondering... in addition to lowering the titration of my WVO, is it also helping in dewatering? I had a rather yucky batch of oil. I am using "dry" glycerol. That is to say it did not come from a 5% prewash batch. Is it possible that the pretreat also takes out some water?

It will dry your oil, lower your titration and lower the amount of methanol needed all in one fell swoop!

I am interested in all three of the above (drying, lower titration, less methanol), but at this point am still just experimenting with this. I added 5 gallons of glycerol to 40 gallons of oil and heated it for my normal dewatering cycle, 200F, 5 hours pumping with venturi and condensor running. Let all settle overnight. Now when I pull off the glycerol it is way thicker than at the start and only 2/3 the volume. I'm wondering...do I even need to draw off this glycerol pretreat? Could I just react with it in there and then just pull off more glycerol after reacting?

Looking at my previous post, it dawned on me that the reduced volume of glycerol was due to its methanol content being distilled off during dewatering. I'm thinking that's not quite what I want to do. Still wondering if I can just run the pretreat glycerol through during my reaction. I have enough reserve capacity in the reactor to accomodate it.

quote:

Originally posted by PbIntoAu:
. . . I'm wondering...do I even need to draw off this glycerol pretreat? Could I just react with it in there and then just pull off more glycerol after reacting?

Yes, you could. But you would need a huge pump or mixer to keep the starting volume and ever increasing amount of glycerol stirred up in the reactor as the reaction proceeds to completion.

The methanol with its dissolved catalyst is absorbed into the glycerol molecules. More glycerol means more methanol/catalyst becomes trapped in the glycerol. Just because the methanol/catalyst becomes trapped in the glycerol does not remove the methanol/catalyst from the reaction. But, the mixing energy required to continuously mix and shear the glycerol becomes greater than that required in a normal reaction. Extra mixing and shearing of the glycerol/methanol/catalyst is needed to continuously allow exposure of the reactants to the unreacted oil (triglycerides).

Thanks producer! I don't think my pump is up to the task of the extra mixing. With the thicker glycerol I think I'll try using Graydon's method of tapping it off three times to get it all. It's so thick that the first time draining doesn't get it all.