Hello Joe
Hi Keith See my answers below;
Keith Addison wrote:
Hello Joe
Hello, I have a question about biodiesel processing I hope someone
can help me with;
I read the excellent info on the journey to forever site and
checked the archives about washing etc. I am interested in using
mechanical agitation to speed up the process of washing but I
wonder if I am being too impatient or something.
Did you see this post?
http://www.mail-archive.com/biofuel@sustainablelists.org/msg37937.html
Re: [biofuel] Circulation with pump washing.
I just read it. Thanks.
I don't think hot biodiesel fumes are very good for you. The smell
is certainly more aromatic.
This is the first I have heard of this. I thought I read on JtoF
that BD is completely non toxic.
It is, but does that also mean the fumes from heating it to a high
temperature are harmless? I don't know. I've seen some people
claiming it's harmful but without any details and I've never been
able to find any real info on it.
I'm afraid I'm a dumbo when it comes to vacuum, I don't know what
that means. Did you let the glycerin by-product settle and separate
it before distilling off the excess methanol? If you did it
straight after the reaction you probably sent the reaction into
reverse, converting soaps back into FFAs, which dissolve in the
biodiesel and can't be washed out (and are not good for your
motor). Either way, I doubt you'd succeed in removing all the
excess methanol by distillation, most perhaps but not all. If you
distilled it off with the by-product still in the reactor there'd
still be quite a lot left in the by-product - without using vacuum
you'd need to finish at a temperature of about 150 deg C to get it
all, or nearly all. Anyway if you washed it thoroughly there won't
be any methanol left.
I let the glycerine settle overnight and then I turned the rercirc
pump back on and mixed it all up while heating to 55 deg C. Then I
used vacuum until the distillate stopped and then vented and allowed
it to separate again.
I doubt you got 100% of the methanol out that way, and you do risk
reversing the reaction.
I drained off the glycerin and added hot tap water ( I used
deionized water in my test batches that is one difference) and
recirculated for about an hour. After washing I would let it
separate for two hours and then drain the water and repeat. I used
3 wash cycles. The last wash water came out almost clear.
Try another wash cycle. Washing it in the processor runs the risk of
contamination with residual by-product. See how it goes, you might
have this problem later and need a separate wash-tank.
Does the cloudiness indicate that the reaction was not correct
(excess caustic?)
If it's really persistent it might do. But you haven't told us very
much about what you did, titration etc. - how did you measure the
pH? Did you measure the pH of the final batch of wash water? It
should be the same as your tap water. There are quite a lot of
variables in transferring a process from a one-litre test batch to
a bigger processor. You might need to experiment with agitation
times. What's the volume of your reactor, only five gallons?
I used phenolthalien (a few drops) in 4 ml oil mixed with 40 ml IPA.
I stopeed when the color lasted 10 seconds. I don't have my lab
book with me at work here but I think it came out around 3.5 ml of
0.1 % KOH soln per ml. Following the recommendations regarding the
assay of my KOH I ended up deciding on 10.6 g KOH per liter of oil
for my process. I did get a good clean split this way.
Sounds good.
I haven't tried reducing the concentration of caustic yet. I
haven't measured the was water ph. I will do this.
Yes my batch reactor is pitifully small. It is a 36 liter hot water
tank. Since I walk to work year round my fuel needs are relatively
low and my Golf TDI sips fuel rather than being a big gulper so I
opted to build a small system that fits in my basement.
I don't think that's pitiful, Joe, I think it's admirable, especially
in view of your previous message about the footprints we make on the
face of this fair planet. We fuelled our Toyota TownAce for nearly a
year with a 20-litre processor, this one:
http://journeytoforever.org/biodiesel_processor5.html
Simple 5-gallon processor
The TownAce isn't nearly as economical as your Golf, and we also
fuelled a few tractors and provided biodiesel for demos and for
people coming to our seminars and so on. Now we make 60-litre batches
but we still use the 5-gallon processor. Lots of people have copied
it. I do wonder about people, especially in the US, who just seem to
be ordinary folks, not farmers or businesses with fleets or whatever,
but they say a 200-litre processor isn't enough for them.
I use forced exhaust to take any fumes away from the methoxide
mixing and the vacuum pump exhaust when it is running. So far it
works ok except I guess I am pushing the process just a tad with
regard to the washing and drying. I'll give it more time next time
and see if it improves.
I'm quite sure it will. Strength to your arm.
Thanks for your suggestions.
You're welcome.
Best wishes
Keith
Joe
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