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Soap in oil feedstock and other horrors - newbie error some 10 years ago
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Hi folks
I'm just back to making BD after at least 10 year break. I wish I'd had had broadband and make-biodiesel.org back then, and that i'd used ebay a bit more, but at least this forum was on the go! Sorry, what follows is a bit long.

When I first started I did something a bit daft, because I was not really paying attention and I was just plain stupid (and young and nieve, I blame FTFTTFT for making it all sound too easy!). I foolishly mixed my NaOH and methanol into cold oil, without mixing them together first. Sounds daft I know. I just flung them all in a massive tank and pumped it around for a bit and hoped for the best. Of course it just made glop.

I then had to move house and change sheds and I pumped the lot into 2 55 gallon drum and left it. Later on I successfully reprocessed some of this with some help off here but the threads must have been archived now as I can't find them, and I'm not sure what I did.

Anyway to cut a long story short. the tanks have now been sitting unmoved for 10 years or so so they are pretty well settled! I know what layers there are, despite not being able to see inside the drum because I also have a plastic 20 litre drum with the same stuff in it.

Here is a brief description of what I have:

  • The top 50% seems to be something approximating biodiesel - smells like it and has similar viscosity though it is a bit dark, a bit too opaque and the specific gravity was about 920 so perhaps this is just a thin oil with methanol in it

  • Below that it what looks like the oil I originally got hold of which was industrially recycled, guaranteed very water free, and a bit thick.

  • On the bottom of that as far as I can tell is lumps of soap. I guess if you just throw a load of NaOH granules into oil you are going to make some lumps of soap.

  • I am sure there is a fair amount of methanol still in there too - I know the barrels have miraculously remained airtight over the years because there was a vacuum when I opened them and I have often heard them 'ping' as they expanded and contracted as the ambient temperature changed.

  • I can't seem to see any glycerin in there which makes me think that it is unlikely that any of the oil reacted and turned into BD if the catalyst was not properly dissolved, and just busy making clops of soap. so the top layer is maybe not BD?


I can pump off the well settled mess from the top down with my barrel pump 'layer by layer' and try to deal with the fractions individually.


So I'm hoping for some kind advice on rescuing this mess! My plan is as follows:

1) separate into 3 layers - runny biodiesel-ish, thicker oil; soapy mess

2) coarse filter the obvious lumps of soap out of all segments using a kitchen sieve (these lumps can be as big as a an inch or two across, though admittedly these would not get though the pump) - deal with soapy mess later

3) Do some testing on the top segment to see it its biodiesel. As far as I can think and from what I've read i should probably do

a) a 3/27 (which it will definitely fail! but might be a good benchmark of how bad it is?)
b) measure SG,
c) heat to above 65 deg to flash off methanol, let settle, and see if any glyc. drops out with methanol gone
e) try some test batches with the standard reprocessing recipe and see if I can get some good separation.
f) I think I should probably try reprocessing on both heated (de-meth'd) and unheated samples, with different amount of methanol, given probable methanol content.
g) If I can get some good separation, tinker with the reprocessing amounts in test batches until i get as little dropout in a 3/27 as seems realistic?

4) after this testing I would hope to be able to reprocess the top segment and get some ok-ish fuel.

5) Then there is the veggie oil segment. I am pretty sure there will be soap in this segment and come to think of it in the top segment too. Should I try to wash this out and then dewater the oil again? I'm reluctant to introduce water particularly as none seems to have settled out in 10 years to the bottom of the barrels. I wander if a glyerine prewash would be the best way to go? I have no glycerine sitting around but maybe I could find somebody local

6) I haven't yet researched what to do with the soapy lumps, any advice would be greatly appreciated!
 
Location: Just South of Edinburgh, Scotland | Registered: January 08, 2002Reply With QuoteReport This Post
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If the stuff is 10 years old I would just get rid of it and start over with fresh oil, the stuff is biodegradable after all...
Cheers,
Jon
 
Location: Wellington County, Ontario Canada | Registered: February 07, 2008Reply With QuoteReport This Post
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