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Small amount of glycerol in final product

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May 18, 2015, 01:33 AM
Small amount of glycerol in final product
Hello everyone, hope youre doing fine.

Im experiencing some issues lately.
I prefilter biodiesel with woodchips.
Samples taken from what comes out of the wood chip barrels doesnt contain glycerol at all.

Last batch, after resin polishing i found a really small amount of glycerol dropping out.
Could it be contaminated resin?
Should it be time to change it?

Eduardo G
May 18, 2015, 05:35 AM
Hi Yuka,
I think you will find either it hasn't been de-methed properly or settled long enough before passing through your resin.

presumably you do de-meth, if there is a small amount of methanol left then there will also be glycerol present.

In any case I would flush the resin with methanol to remove any glycerol, then purge with good bio (which you can reprocess)

May 19, 2015, 06:59 AM
I evaporate methanol by heating and recirculating, blowing air with a fan across the open SS tank.

Tank is 300 liters.
How long should i evaporate?

Here is a video so you can get an idea.
Any suggestions are welcome.

Eduardo G.
May 19, 2015, 10:52 AM
Originally posted by Dgs:
Hi Yuka,
The only thing I can tell you is how I do it, which is with a compressor blowing air at the bottom. I leave it for 2 1/2 hours at 50 degsC. This is a 200 litre batch and I do water wash afterwards.

I also have no ventilation and simply keep well out of the way while the evaporation takes place.

the symptoms you describe are in keeping with a small amount of methanol still being present. If that is the case there will also be glycerol.

May 19, 2015, 07:25 PM
Thanks my friend.

Eduardo G.
May 20, 2015, 10:35 PM
Problem solved.

Moved the centrifuge that i use for wvo, to polish biodiƩsel and remove the glycerol.

As it has heaters (UsFiltermaxx) it actually evaporates almost all the methanol while polishing the BD.

I settled and drain all the glycerol.
BD was at around 5,000 ppm.

I ran the centrifuge at 3,000G's an fed it at 40gph.
I am amazed with the amount of glycerol that came out, since i had already settled and drain almost all glycerol.
Contamination reduced to 890ppm.

Video links;

Polishing BD, methanol evaporation;

Glycerol sludge drain;

Left is crude biodiesel at 5000ppm
Middle is centrifuged biodiesel at 890ppm
Right is water/soap/methanol that came out from the drain. (It smells really strong from the methanol)



May 27, 2015, 12:25 PM
Legal Eagle
If you still have that much glyc after processing then I suggest a modification in the method yo use.
After processing if you allow 24hrs for the mix to settle and then siphon off from above the glyc layer you should not be seeing that much residual. And once the demething and further settling you should not be seeing any at all.

When I first started with dry media filtering I took samples and had them GC analyzed and the results were that I got ASTM quality after demething and settling only and of course it was only better after dry media and resin. But the whole thing starts with not allowing glycerine to get into the cycle to start with and that is done at processing and settling.


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