Hi Joe,
Thank you for the kind words ..... your timing couldn't have been better.
The instructions were just as clear and readable when I started making BD.
I can't imagine how I screwed up so much and so often. With patient help from
list members even I met with success. It's hard to tell what phrase or bit of
advise clears the fog for a given biodiesel newbie. I remember scaling up and
then dealing with 100L of glop when Keith advised me to use the directions as a
guide. Blasphemy!!! Follow directions to the letter I thought. That idea freed
me. I had learned the process doing small test batches, graduated to WVO and
was now beginning to scale up. I learned how to break emulsions, now it was
time to learn how to avoid them. Tweak the temp, decrease the volume a bit,
increase processing times. What a wonderful feeling of freedom. My mistakes
had taught me a lot.
Do you remember wondering if you'd ever make BD that passed the methanol
test? Tweaking based on an understanding of the process was the key.
I only hope that my little "synopsis" helps someone who doesn't already
know everything in it.
Hey, good news. Just got a good price on barrels of methanol.
See that, a few kind words can turn someone's day around.
Best to You,
Tom
----- Original Message -----
From: Joe Street
To: biofuel@sustainablelists.org
Sent: Wednesday, May 09, 2007 11:41 AM
Subject: Re: [Biofuel] Re-processing troubles
Hi Tom;
Excellent synopsis on 'how to do it right'. Although this is the same
information that is there on the journey to forever website and probably a
hundred times over here on the forum, I wish there was a way to bold it in the
archives or something. The message should show up in red in my mailbox.
Thanks for taking the time to put it so succinctly.
Joe
Thomas Kelly wrote:
Hello to All,
It is my impression that a thicker than "paper thin" middle layer in
the wash test may not indicate an incomplete reaction, but rather excess soap
production. This may be due to high FFA content in the WVO oil, water in the
oil, water in the caustic, or in the methanol. It may even be due to too much
caustic.
For these reasons, and others, beginner's should start with small (1L)
test batches using virgin oil, the highest quality chemicals, & balances that
allow accurate measurements.
Much of the soap settles out with the glycerin, as does most of the
caustic and excess methanol. Even after 12 or 24 hours of settling some of the
soap, caustic and excess methanol is still in the biodiesel fraction. That's
why we wash it. The amount that remains is related to the amount produced in
the reaction.
Using virgin oil eliminates not only the need to titrate, but also
soap formed due to FFAs in the oil. Initial test batches with anything other
than the "paper thin" middle layer (wash test) are unacceptable because it
indicates either an incomplete reaction or excess soap. Given virgin oil,
accurate measurements, and quality chemicals excess soap should not form.
After success with small (1L) test batches using virgin oil, one may
begin using WVO and eventually scale up to larger batches. This not only
increases the volume of a potential disaster (Emulsions), but also increases
the number of variables that must be considered when a problem arises.
How do you know what is causing the problem?
Become familiar with the methanol test (Quality Testing) described at
JTF.
If there was an incomplete reaction and various glycerides remain in the
"biodiesel", they will remain undissolved in the methanol ----> a residue at
the bottom; reprocessing is in order. If the entire sample of BD dissolves in
the methanol, but the wash test resulted in a thicker than "paper thin" middle
layer, the problem is soap formation. If using virgin oil, (or low titrating
WVO) and too much soap forms, consider the presence of water or improper
measurement/calculations.
Ex:
During methanol recovery (from glycerin mix) one must consider water
contamination in the distillate. Using the recovered methanol may result in a
complete reaction with little soap (good methanol), complete reaction with more
soap than expected (some water contamination), or incomplete reaction with a
lot of soap (serious water contamination).
The more serious problems are invariably associated with last liters
of methanol that were distilled. I have had a similar experience using the last
gallons of methanol from a barrel. As the barrel empties, water in the air
condenses ----> more water in final gallons.
The wash test and the methanol quality tests are both valuable.
Towards the end of each reaction, I shut off the pump and draw off a
sample of the mix, and then turn the pump back on. I let the mix settle for
about 10 minutes and then do a solubility-in-methanol test on some of the BD
fraction. If it passes, I pump the mix into my settling tank. If I'm making
fuel for my car, and the BD fails the test, I'd add a bit more methoxide and
continue processing. If I'm making fuel for my oil-fired boiler (larger
batches; only 16% methanol vol/vol) a small residue of unreacted oil is
acceptable. Testing this way saves the expense of time and resources involved
in reprocessing.
Prior to washing a batch I always do a wash test. If the batch passed
the methanol test, but there is a thicker than "paper thin" middle layer I may
let it settle longer, or put a few extra ml. of phosphoric acid in the first
wash water.
Having passed the methanol test, I wouldn't consider reprocessing.
Tom
----- Original Message -----
From: Matt Wilson
To: biofuel@sustainablelists.org
Sent: Tuesday, May 08, 2007 2:44 PM
Subject: [Biofuel] Re-processing troubles
Hi all,
Reading Shawn's post today was interesting because I was going to post
myself about a re-processing question.
I started making bio with 1 and 2 liter batches as per the instructions
on Journey to Forever (thanks again for the great site!), and had moderate
success, just like Shawn. I would have a small emulsion layer, perhaps
1/4-1/2" in the first wash. Talking to some local "biodieselistas" here in New
Mexico, they said go ahead and wash it, and if by the third wash it separates
quickly and cleanly, it's probably alright. Well, I got curious and tried to
reprocess a batch anyway as per the directions of JtF:
"If you have an emulsion any thicker than the normal "paper thin"
interface layer between oil and water, the batch should be retreated. Retreat
as with fresh oil, with the standard 3.5 g of lye per litre of oil but using
only 100 ml methanol per litre of oil."
My batch separated out a bit more glycerin, but when when I went to wash
it, it turned into "Milk" and, to this day, has not separated. I didn't think
much about it and kept processing small batches until I got one that worked
fairly well.
Okay, fast forward a few months: We built a 55 gal. drum processor and
have done four batches with it. The first one came out with a bit of an
emulsion later (more than I wanted), so I increased the processing time to two
hours. Second batch came out much cleaner. Good wash, nice clear fuel when
dry. The third batch I messed up by miscalculating the amount of lye...used
3.5g/liter (as per NaOH) instead of the 5.5g./liter I actually needed for our
90% KOH! As you can imagine, the batch came out pretty badly! We settled out
as much bio as we could and after three washes used about 25 gallons of this
and 15 gallons WVO in the next batch.
I preheated the batch to 140 degrees (to dewater), let it settle for a
day or two, and titrated. It titrated at 1.5, so I used 1050g. of lye (150
liters of oil, and 30 liters of methanol), and reprocessed as per a batch of
WVO.
When I went to do a 2nd wash this morning (forgot to do a bottle test-
doh!), it came out as tan milk. It had settled overnight. There was no
biodiesel on the top- the whole batch looks like a latte!
I am going to try to separate out at least some of the batch, but I'm
afraid to try to re-process again. Meanwhile, I've got 40 gal. of muck I have
to get rid of....
Any input would be welcome!
Thanks for the time,
Matt Wilson
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