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Biodiesel | 25 comments (25 topical, editorial)
Re: Biodiesel (3.00 / 0) (#3)
by troy on Sat May 21st, 2005 at 09:29:00 AM MST
(User Info)

Fundamental key questions:
  1.  Did you test the waste veggie oil for the presence of water?  If so, how did you test and how much water was present?
  2.  Did you titrate the used veggie oil to find out how much NaOH to use, per liter of oil? If so, what did the test indicate?
Your answers to these two questions will determine the future of your gloop.

Finest regards,

troy



Re: Biodiesel (3.00 / 0) (#5)
by wildbill hickup (wildbill_hickup at yahoo.com) on Sat May 21st, 2005 at 11:43:38 AM MST
(User Info)

Hi Troy,

Based on all your previous posts I was hoping I would hear from you.

I'm still very new to this so the answer to your first question. I'm not sure how to test for water although I brought the WVO up to steaming temp and kept it that way open lid for 2 hours, hoped that this removed all water. All oil is from the same source, to date I have made a dozen small 1L batches for practise and this was my 4th 20L. All other batches seemed to work fine with the exception of one 1L that did something similar but not as much. There was just a little gell near the bottom on that one and it cleared in about 3 days.

Second question (I was a bad boy) Since everything was going well I skipped the titration. I did use same quanities as in previous batches, in short. 6.5g lye, 200ml methanol per L WVO. Guess this is what I get for cutting corners.

[ Parent ]



Re: Biodiesel (3.00 / 0) (#10)
by troy on Sat May 21st, 2005 at 04:22:10 PM MST
(User Info)

Yup, failure to titrate will sooner or later bite you in the a$$.  If you have any of the original oil, it would be interesting to know.

What follows is a copy of a procedure I wrote up for another board.  This spells out the water test in painful detail.  You probably don't need that much detail, but you'll still get through it.  If you did have much water in there, you may have unusable glop.  Hope that helps, and feel free to ask more questions.

PS, don't burn the glop, as burning glycerin can produce toxic acrolene (spelling?) smoke unless it's a very hot fire with very complete combustion.

Water test procedure for vegetable oil.  You need an accurate scale that can precisely measure weight with a resolution of 0.1 grams (a tenth of a gram).  Ebay has lots of vendors that can supply a manual triple beam balance that works beautifully.  There are digital versions as well.  The scale should have an upper capacity of about 500g or more to do this test well.  You could fake it with a top capacity of 100g, but you have to use a much smaller sample and you lose some precision.

  1.     Find a container to put an oil sample in.  Gladware works nicely (semi-disposable "Tupperware" and available at any supermarket or Wal-Mart).  It's about the right size, cheap, lightweight, re-usable, see-through and heat resistant at the temperatures we're working with.
  2.     Weigh the empty container to the nearest tenth of a gram and record that somewhere.
  3.     Take a 300 to 400 mL sample of oil.  The sample should be representative of all the oil you are going to react.  So typically, I dump all my oil into my processor tank and stir it for ten or fifteen minutes.  Then I take the sample.
  4.     Weigh the sample.  Record this number.  Subtracting the weight of the container gives us the actual weight of the oil. Record oil weight.  I designate this as "wet weight".
  5.     Heat the sample in a microwave until the oil reaches a temperature of 240F.  Harbor Freight sells a nice probe thermometer with a 6" metal probe with a round thermometer head at the end.  A candy thermometer would work as well.  Check your thermometer in boiling water and confirm a reading around 212F.  Some are a mile off.  During the heating phase, you will get a qualitative indication for the presence of water.  If your sample starts to spit and boil around 212F (100C) you know there is some water. We'll get quantitative data in a few minutes.
  6.     Allow the sample to cool off for ten minutes or so.  This allows any residual emulsified water to evaporate, plus it's safer.
  7.     Weigh the sample again, record that number.  Subtract container weight.  This is your "dry weight" of the oil.
  8.     You can see where this is going.  Take wet weight and subtract dry weight.  The difference is the weight of the water that was in your sample.  Now divide water weight by the original "wet weight" and this will give the decimal fraction water content of the sample.  Multiply by 100 to get percent.
Here's an example:

Container wt:        26.2g
Total wet wt:        335.6g
Wet oil wt:        335.6g - 26.2g = 309.4g
Total dry wt:        321.6g
Dry oil wt:        321.6g - 26.2g = 297.4g
Water wt:        309.4g - 297.4 =  12.0g water
Water content:        12.0g / 309.4g = 0.03878
% water by wt:    0.03878 x 100 ~ 3.9% water by weight

If I'm careful, and without heroics, I can measure the presence of 0.2 grams of water in a 500 gram oil sample.  That would be:

0.2g/500g = 0.0004 water, or 0.04% water.  

So even if you're sloppy, and only measure gram amounts, you can still learn a lot about water content with a scale and a microwave.

Summary:

Weigh
Heat
Weigh again
Do math stuff


[ Parent ]



Re: Biodiesel (3.00 / 0) (#13)
by ghurd on Sat May 21st, 2005 at 05:09:14 PM MST
(User Info)

Very new to the mechanics.
I should say new twice.

What about 1 gallon of filtered (5 microns) waste to 20 gallons of diesel?

G-

[ Parent ]



Re: Biodiesel (3.00 / 0) (#14)
by ghurd on Sat May 21st, 2005 at 05:11:00 PM MST
(User Info)

Just WVO and road diesel.

[ Parent ]


Re: Biodiesel (3.00 / 0) (#21)
by wildbill hickup (wildbill_hickup at yahoo.com) on Sun May 22nd, 2005 at 07:34:03 AM MST
(User Info)

THanks for the info on water testing AND no skipping titration from here on out. Now to my problem at hand. You said don't burn it and I had read that it's not a good idea, so what to I do with this stuff, turn it into soap(if you have a recipe that'be great), is it safe to dump, etc. At this point I just want to get it out of the reactor so I can move on. I guess as I said before I'll put it into 5 gallon buckets and play with small quanities (more lye, more meth, a little acid) to see if I can make anything happen, but any more ideas as to what to do with the bulk of it would be a great help. Thanks for all your help so far and I promise NO MORE SHORTCUTS!

PS Got a scale ordered.

[ Parent ]



Re: Biodiesel (3.00 / 0) (#25)
by troy on Tue May 24th, 2005 at 04:51:37 PM MST
(User Info)

You could do mini batches of one liter, done in a 2 liter pop bottle.  On the best biodiesel discussion board in the world (not that I'm biased...http://biodiesel.infopop.cc/eve/ubb.x/a/cfrm/f/498605551)this is known as the World Famous Dr. Pepper technique, as popularized by a biodiesel wizz who goes by Tilly.

Anyway, the idea is, you put a liter of oil (or glop) in a 2 liter pop bottle, and then add a bit more methoxide (methanol + lye (sodium hydroxide, you knew that...)).  And see if it helps.

You're pretty much screwed as far as determining if you have water in the batch, because if you boil it to check for lower weight, you'll boil the methanol off too.  So you won't know if the change in weight is due to the water or due to the meth.

You can burn the glop, but it's got to be done in a nice hot fire, where the glop is NOT the primary fuel source.  Think nice hot wood or coal fire, outside, built around a can, to which you add a quart at a time or something.  Or you can build a "Turk" burner, which is a forced draft thing, then feed it 50/50 diesel and glop just to get rid of it cleanly.

I have read several sources that say glop makes really good herbicide.  And the meth just evaporates with lots of fresh air dilution, so that shouldn't be a big deal.  I have no first hand knowledge of disposing of glop however...

Good luck and have fun!

Troy

[ Parent ]



Biodiesel | 25 comments (25 topical, 0 editorial)

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