I added 8% glycerol to 40 gallons of highly used WVO. The WVO originally titrated at 16 m/l. I then added the glycerin to it in a slow mix for about 5 minutes, let it set for 12 hours. I put it in my reactor then heated it and titrated it. Came out to 9 m/l using KOH. Just processed the oil this weekend. washed and came out great!

Yeah, I've experienced some hit-or-miss results doing this to. Adding the glycerine byproduct will precipitate out the tallows and animal fats, so if the high FFA content is from them, you see a reduction in the titration. If its not (as one attempt of mine was), little to no change.

I have experience 16-17ml KOH down to 9-10 ml KOH, and I'm going to start mixing a portion of this 9-10 oil into my future batches of typical 5-6 oil.

But adding the byproduct will ALWAYS help winterize your fuel, as it reduces the content of the highest temp gelling components.

I don't think the drop in FFA is really related to tallows. It is hit and miss because your byproduct varies.

One effect is from excess methanol washing FFA out of the oil. So it depends how much methanol is still in your byproduct.

The other effect is from the caustic turning some FFA to soap which then perhaps drops out with the byproduct, or at least dosen't register as acid anymore when you titrate. Some may stay in the oil and may tend to give a more alkaline reading; I don't know for sure. This depends on how much unconverted caustic is left in your byproduct.

You could try small test batches using byproduct and addding in extra methanol or caustic or both to see how results varied.

You would want to be recovering your methanol afterwards of course.

The tallows dropping out is a seperate and largly unrelated effect to FFA reduction. Though potentially valuable for winterisation.

In my experience tallows come from food that has been cooked and usually have less FFA than the oil itself.

Hey Tpilgram was your glycerol straght or did it still have methanol mixed in??Was it recovered?

ANT,

Forgive my ignorance, but above you mentioned excess meth washing out FFA. Are there any test to show reduction numbers? I understand the meth must be recovered to be economically feasible.

thx

I've done quite a bit with this method and it does clarify the oil(tallows and heavy fats) and I beleive the the methoxide left over in the glycerin will start a "low and slow" transesterification and lower FFAs a bit if you leave it in there for a while. I arrived at this conclusion because the longer I left it in there the lower the titration became.

Also, it also adds QUITE A BIT of soap since the glycerin has a bunch of that, so if you are waterless washing you will add work to the back end of the process. Also, if you are adding water at the end of your reaction, the water in glycerin will wet your WVO and even adds more soap.

I stopped doing it when I stopped water washing.

NCDiesel

NCDiesel's post:

quote:

Also, it also adds QUITE A BIT of soap since the glycerin has a bunch of that, so if you are waterless washing you will add work to the back end of the process. Also, if you are adding water at the end of your reaction, the water in glycerin will wet your WVO and even adds more soap.

I've been using variations of this technique for about a year and I've decided on a proceedure. I'll use it on my next batch, which makes NCDiesel's post very timely.

I'll add 5% dry glycerine byproduct to my next batch and circulate as I heat. When the reaction is complete I'll draw off the dry glycerine after 1/2 hour then do a 5% water prewash. Then after 1 hour draw off the wet glycerine and store it seperately from my dry glycerine.

I think it'll make better fuel because the dry glycerol added at the beginning of circulation will add extra methoxide. Also, the dry glycerine will help to absorb any water that might be left in the WVO (it has a tendancy to suck up water) making a dryer reaction.

When the reaction is complete I'll do a water wash. I've got plenty of water and my catalyst is KOH.

Hey, I like that! Make the process more light-water contamination tolerable.

So;
add oil,
add 5% DRY glycerine,
add methoxide (1 stage base or 2, by preference)
react,
separate slightly less dry glycerine back out,
5% water pre-wash,
continue as normal...

NEAT!

Thanks Ryan. Glad you like my idea. I'll tell you how it goes but I doubt I'll be able to tell the difference. It just seems like a good idea. Always looking for a way to make slightly better fuel.

Ryan's Quote separate slightly less dry glycerine back out,

The oil is already fairly dry having been heated to 150F+ and settled for 24 hrs or more and drained from a standpipe like steel barrel. We all know that the dryer the oil the better the reaction.

Also, there is that interesting thread here that adds a spin to this idea. Maybe 10% dry glycerol byproduct would be even better.

adding glycerol byproduct to raw wvo lowers the titration in two ways.

1) The glycerin and FFA bond to create a mono-glyceride. We all know the transesterificaiton process can be reversed if you mix biodiesel with glycerin (no methanol).

2) esterification directly to biodiesel occurs with the methanol and FFA. Acid is not required, it is simply a catalyst to push the reaction along faster.

Factors such as the amounth of FFA's, amount of methanol, amount of glycerin, heat, and time will all affect the speed and percentage of conversion.

quote:

2) esterification directly to biodiesel occurs with the methanol and FFA. Acid is not required, it is simply a catalyst to push the reaction along faster.

By adding straight byproduct(straight from the reactor) you are adding soap and catalyst with a little water. The Catalyst will form soaps from the FFA and the glycerine already contains high soap amounts so it won't be able to take out as much.

I think if you acidfy the Glycerine to break it apart then add it the results will be much better. First you are adding more FFA to the UVO, but you are adding Methanol, Glycerine, and Salts Also. If you break it long before adding it to your UVO then it will have time to convert FFA to biodiesel. When you add it you would convert more FFA to Biodiesel if there is enough methanol. The glycerine will settle out possiably taking out tallows and most of any soaps that are possiably formed. The Salts should hurt anything and settle or come out in the washing process.

I have not tried this yet, but I am working on the concept. I currently acidfy(sp) my glycerine to break it and mix to convert my FFA to Biodiesel. Then I add the biodiesel/FFA to my next batch that requires Acid Esterfication. Then I recover Methanol from my glycerine. To help this process along when I recover Methanol from my Biodiesel(for ease of washing) I put that methanol into my glycerine mix to promote it's use in FFA conversion. I also feel it helps by consolidating water from the recovery process and setteling it out into the glycerine. Instead of it compounding into the Methanol little by little everytime it is recovered.

Logan Vilas