New to posting, I have recently tried a raw glycerin prewash for my crappy oil I collected this week. Hot in the past month here in LI NY.
The oil in the 250 gal container from where it came from had that smelly formented odor. Heated it, settled & dewatered it and filtered it as usuall still with that odor. Titrated at 4.5. The highest I ever had. Passed the hot pan test for moisture and still smelled. Heated 200 gallons of this oil to 120 degrees added 40 gallons raw glycerin and mixed for 45 minutes. Using NaOH as my usual catalyst, I drained the next morning and it was very thick but pourable. Yielded 5 -8 gallons less of gycerin. Heated oil back to 130 and now titrated at 4.0. Was'nt too happy!! The oil did have that methoxide odor to it but still treated it as normal 20% methanol and 6000 grams of NaOH. Seems that some hardened glycerin was on the side walls of my processor and saw it spinning in the early stages of my process. The pump and heat liquified it. The end result was no better at all. Drain out 50 gallons of glycerin. What did I do wrong, if anything??

quote:

Originally posted by Andrew Morris:

quote:

methanol definitely gets mixed into the oil with glycerine pretreatment.

Right. The question would be how much stays in the oil given the limited solubilities of oil and methanol? And, is that enough to have a significant effect on conversion - ie can we use less methanol and still reach the the same level of conversion?

I am a biodiesel newbie, and chemistry was a sore spot in college. With that said, i will share my observations. I have regularly been pre-treating with no less than 20% glycerin. It only costs me time and saves on KOH by lowered titration. My last batch was run with 18% methanol instead of the ususal 20% and it passed the 3/27 with flying colors. When I demeth and settle for 24-48 hours, soap is minimal. I believe that some methanol is cooked out during the mixing process, so I apply about 10 lbs of pressure to my settling tank to reduce this. I say this because I vacum my methoxide and oil through a reaction chamber into the settling tank and I always find some methanol in the air compressor tank.

One other person has indicated to me that they pre-treat and they are using 16% methanol regularly. I plan to work my way down to that percentage.

And finally, I drywash with Magnesol, but I have found that after de-mething and settling I have fuel that is almost as clear as the drywashed fuel.

I just treated 50 gallons of dry WVO with 12-13 gallons of glycerine from my 50gallons I have stored. I mixed with heat for 2 hours and settled over night about 10hours.

I then drained exactly 10 gallons of glycerine, it was thicker still able to pour, but did not smell like methonol at all!

I now have 52-53 gallons in the reactor, i'm proceeding with my acid stage using 250ml of acid and 4 gallons of meth

Inital titration - 16
After glycerine treatment - 8.5 ( happy !!! )


I'll post to let you know how I did after the acid stage

Dear Lauf
Why didn't you treat again with glycerol so you don't have to do acid treatment? It's a hell of a lot easier and safer.

Well I have a biopro so it's setup using the acid step then base. I dont understand why so many people say it's not safe? I pump out of my barrel into measureing cup and pour into reactor? easy process! wear gloves and glasses duh!


Okay anyway after I did it I ended up with a layer of white/yellow glop, kinda seemed like water? Hard to say.... My titration did not change

Since I have started to pre treat with glycerol, if I have 1 or 2 tritrate on 50 gal of oil I get 50 biodiesel 80/20 and 5% water pre wash. And 50 gal. oil 7 tritrate I get 45 gal bio diesel 80/20 with 5% water prewash. After all draining I am running the processor with the lid off and getting rid of the methanol this forces the remaining soap and glycerol out. I finally feel like I have made some progress.

Are you distilling methanol out of the glycerine before re-introducing it or leaving it in there? If it is left in there, is that why you guys are talking about 18% instead of 22% methoxide?

18% methanol is what I use with success, and I do use glycerin that has methanol in it. As of late, I have been forced to move my base KOH up to 9g/L to have good reactions. This appears to be a KOH quality problem.

Many times I see people report that they "gain" oil by using the glycerin pre-treatment. I personally think this is due to biodiesel that is present in the glycerin container from prevous drains of reacted batches.

I just tried this for the 1st time. My oil typically titrates at 1.9 - 2.1. This time I titrated at .9 If I gained any product it was only a few litres. I processed with 18% methanol. I found the whole process easier than if I hadn't pre-treated but I don't want to speak too soon as I am still in the wash stage. One thing I am noticing is soap bubbles in the wash water. I am not used too seeing this. I'll post later when I am done washing and drying. I didn't do a 5% pre-wash and used a base of 7g KOH.

I think that the "gain" people see in the glycerin pre-treatment comes from biodiesel that is drained out with the glycerin after the reaction. You don't actually gain oil.

I have also noticed that I have very little soap production as the glycerin usually removes a major portion of the water.

I should mention I didn't need to de-water due to the glycerin pretreatment. I didn't adjust the KOH for purity either, just 7 base + .9 titration. Wash time was reduced by 1/3 and I am now doing an aggressive bubble wash. It's about 4C in the shed now, I don't use heated wash water either.
While I didn't gain any product, I didn't lose what I usually do (about 5%). Anybody considering trying this who has not yet, I'd say go for it. I'm glad I did.

I was also using 7 as my base, but started having incomplete reactions. After reading a thread here about KOH and NaOH quality problems, I moved to 9g, which gives me good reactions.

I have found that adding 1/2 over what the tritration value solved my problems with in complete reactions. I also agree that there is bio-diesel in the glycerin which adds to the wvo after pre-treatment.
Now a question. I have been doing a KOH pretreatment that does lower the tritration value the result is around 7 gals of thick white residue that is in the bottom of 55 gal barrel. I think it might be less loss without koh pre treatment, I now have good luck doing both ways. Has anyone done a study on this approach or is just different with oils and tritration value.

Here's what I have been doing for a few months now in my biopro 190...

Add 50 gal filtered wvo, 10 gal glycerin drained from previous batch.

Heat/stir for 3 hours, heat/settle for 12 hours (sometimes more when I can't get to the machine sooner) Drain glycerin (not to be used again).

This leaves me with anywhere from 50-53ish gallons of oil. I then process as usual and net 48 gal of bio. I wash with hot water, softened by a water softener, and a gal of distilled vinegar.

Have you tried the 5% water pre-warsh. Then I let settle drain and run again and couple of hours this burn the methanol which forces and remaining soap and glycerin out that settles. I have bottles sitting for 1.5 months and nothing that settles to the bottom. I cannot see any reason to do anymore washing. I know others will disagree. But after reading Gram Lemming articles about getting the methanol out and not washing I gave it as try. Of course it would be nice to catch the methanol and reuse it, 1 step at a time that will be next. And I can take the top off my processor to try it, which allowed me to try it.

Be careful about letting the glycerol pre-treatment settle long enough. I have had problems after 24 hr. it's to thick.
So on the next 60 gal. 12 gal glycerol I drained it after 12 hrs. just a little trouble getting started. l then came back 24 hrs. latter and had more drop out. looks like another pint. Now this could be from my tank that is not a complete drain. But I have gained 5 more gallons to process. I will drain again before I process. But the more that settles out the better it should process.
Picture is after 12 hrs. then drain and settle another 24 hrs.

IMG_1465.JPG (47 KB, 80 downloads)

From your picture it looks like your oil was cold, unless it chilled after you took it out. That would make the glycerin flow slow (if at all). I heat my oil to ~120 then add the glycerin and I usually let it settle till the next day due to time constraints and haven't had any problems. But I do have my processor under an open shed and painted black where the sun hits it to aid in keeping the temp up.

I have found that on some cold days (~30F)the whole mix chills too fast for the glycerin to settle out and I had to re-heat and settle; then it came running out like water.

Bottom line is that you are correct in that letting it settle too long means cooler temps at draining and possibly flow problems.

The 5 gallons you gained was most likely biodiesel drained with the glycerin from your final reactions, not gained oil. What I really like is that my oil hardly ever titrates over 1 after the treatment.

quote:

Originally posted by DarrylMueller:
Be careful about letting the glycerol pre-treatment settle long enough. I have had problems after 24 hr. it's to thick.
So on the next 60 gal. 12 gal glycerol I drained it after 12 hrs. just a little trouble getting started. l then came back 24 hrs. latter and had more drop out. looks like another pint. Now this could be from my tank that is not a complete drain. But I have gained 5 more gallons to process. I will drain again before I process. But the more that settles out the better it should process.
Picture is after 12 hrs. then drain and settle another 24 hrs.

You need heat for it to settle properly.

I am heating to 124 f. but this time of year it goes down to 38f. I drained again today and got another 8 oz. It's almost done settling. It would be nice to keep it warm wile it settles. I know it seems like a long time 56 hrs. but it's cold weather. But really gives good yeld with bad oil.