mark,
I;'m not surprised that you don't have a 'glycerine' layer after the
first stage.
First of all, the more I think about it, the more I doubt that it's
glycerine you sometimes see in the bottom of the container at
the end of the first stage- someone correct me again if I'mn
wrong- but if it's an esterification of free fatty acids, rather than a
transesterification of an intact triglyceride, it seems to me that
there wouldn't be much glycerine breaking off other than the very
small amount of trans-e that's (very slowly) occurring.
Jon Van Gerpen's research on this process considers this layer
to be excess methanol, combined with some water that is
formed in the reaction. Presumably there'd also be a little bit of
glycerine if any transesterification is happening as well, all in the
same layer as the water/methanol.
I believe that Todd also calls it first stage methanol rather than
first stage glycerine, and if you look at how 'runny' it is, it looks
like methanol more than like glycerine (at least the few times Ive
seen it).
Van Gerpen's method (that's the exceedingly-high-methanol
industrial process, somewhat different than Aleks' process and
hard to do if you don't have methanol recovery and cheap energy)
finds that depending on the amounts of methanol used and the
amounts of water produced, the excess methanol/.water
sometimes coalesces on top of the esters/oil, and sometimes
ends up below the oil phase. The stuff I saw/made using his
method created a layer that looked exactly like the watery
'glycerine' that I've seen using A;leks' method. However I have not
always produced this aqueous layer in Aleks;' method, and I
frequently used that method with nice oil, just like you. So my
guess is that it's somehow connected to the amount of water
produced, and that the condition of the nice oil might have
something to do with it. I would also guess that how dry the oil is
in the first place would be a contributing factor.
Anyway, I don't worry when I don't see first stage glycerine in
ALeks method, as that seems quite normal to me in my
experience. On the other hand I usually don't look for it, so it may
appear more often than I am aware of.
Todd in the post below suggests removing any first stage
alcohol (the dark layer, sometimes below and sometimes above
the oils).I would add that if you do this change, be prepared to
add a similar amount of fresh, anhydrous methanol, to replace
any that is removed, to make sure there is enough for the
second stage reaction.
mark
--- In biofuel@yahoogroups.com, Appal Energy
[EMAIL PROTECTED] wrote:
Mark,
Earlier I was curious if you were using oil or an oil/fat blend
(WVO).
Should it be presumed that the feedstock at the beginning of
the second
stage and prior to reheating is still liquid? If so, should it be
presumed
that there was a layer of extra alcohol above the oil, perhaps
slightly
darkened?
If so, and were it me, I'd separate the feedstock from such a
layer and then
conduct the second stage, just to isolate variables. Second, if
you're
getting jelly out of a SVO, you might wish to back off the
caustic some.
Jelly, or glop soap is a condition that results from too much
caustic in the
presence of water. It doesn't take much to push what is
primarily a
transesterification reaction into one that is directed towards
saponification (soap making, aka jelly).
You might (or perhaps might not) care to take a look here.
http://groups.yahoo.com/group/Biodiesel/message/2504 It's a
step by step
how to that runs the base side of an acid base experiment in
three
separate stages, rather than all at once.
That's not to declare that it should be done in such a manner.
But it does
indicate that glycerin drop in the second stage can occur with
less than a
requisite amount of caustic.
Take your time and take no short cuts. It works and works well.
Todd Swearingen
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