I've just completed an interview slated for a biodiesel magazine with RolfQuo Biodiesel, which is, AFAIK, the only commercial producer using hard wood chips to purify their biodiesel sans water or resins.

They have a 4 and 4 drum (200Lt each) set up, being 2 on a top tier fed into 2 on a botom tier times 2, so a double set up fed by a small air pump. These 200Lt drums are filled with hard wood chips and have, in conservative estimates, filtered over 50,000 litres so far with no sign of wearing out. The biodiesel is tested going in for soaps and at the outlet; they get it from 800ppm to zero ppm in one pass at full flow rate of 500Lt's/2 hours.

I hope to have the whole article put together real soon so hopefully many will be reading it all soon.

Thats amazing. Look forward to reading your article.. Might have to start looking at putting a lead woodchip column before the purolite one day

How do they get the raw bio to 800ppm of soap before going to the wood chips? Are they using new oil?

Luc,

Are they doing A/E first then transesterification or are they just allowing the soap to settle out first? 800ppm as a beginnning number otherwise sounds really low.

That's a lot of liters without having to replace the chips. It would be interesting to know how many liters before changing out.

Thanks for the report.

The biodiesel is double processed and settled. The 800ppm is typical although the numbers have gone as high as 3,000ppm. For the really high numbers the flow rate is greatly reduced and more than one pass is needed, which they do with a feedback loop but the end result is still zero ppm soap when all is said and done. These guys are morally like Kumar; they just don't believe is sending crap fuel out the door, so it gets tested at several intervals along the way.

I don't know for sure if acid is used, but IIRC it is not, although double processing is standard, and has been know to go tripple if they are not happy with it.

I have a large reverse flow tank that I want to set up as a pre resin tank, but haven't gotten around to it yet. That would be three total, but I am sure it would greatly incease resin life as the chips get out so much gunk to start with there really wouldn't be much for the resin to do except maybe a final polish.

Excuse ignorance, been away for a while, what is double processing please.

Similar to reprocessing. You are doing a single base or a base/base process as normal. the after you pass the 3/27 teat you reprocess with 1 ml per liter methanol and 1 gpl of your caustic for the benefit of pushing the reaction past the point of completion instead of stopping your reaction right on the borderline.

Is there a thread about this push processing ?

Hmmm? You say the 800ppm soap is low for raw BD? The last batch I did, after 5% pre-wash, and one week settling tested at 288ppm using the method from the UBS site. I oil used for this batch titrated at at average of 1.5 over two titrations. I also took the test sample from the bottom of the cone-bottom settling vessel. Could there be reason to believe that I am doing something wrong or is my 288 value reasonable?

dcfly, I did a 5% pre, then dried left over methanol and water and within 1.5 days of settling I had similar soap content to you..in fact less.. raw biodiesel is often in the 1000s ppm soap. I found a 5% pre will take it around a 1000. And thats doing the soap test straight after the 5% pre, not giving any settling time.

Guess not

Stumpy,
I'm not familiar with push processing. By push I can only guess GL's push/pull?
I think Legal Eagle was mentioning double processing, which I can only guess is a two stage base process.
I don't know for sure.

Hi Stumpy

Never heard of it before either. It is not a reference to GL's push pull processor; Just to pushing the reaction to completion. I don't really see how you can push it beyond completion. Might just be my lack of understanding. From what was said it seems that the idea is to be sure that you really do have as complete a reaction as possible even after it passes the 27/3 test. To do this you apparently just take the bio you would consider finished and add 1ml of meth per liter of bio with 1g of caustic per liter of bio and react this to convert any tiny last percentage of un/partially reacted oil. Unlike a normal base/base this is additional meth and caustic not a portion of the original base plus titration. It can be done after a base/base reaction. A final 'just to be sure' mopping up reaction for anything possibly left to react.