Removing water generated in processing?

[thewormman]

An idea for debate   

If its bo11ocks just ignore me, i'm still learning

As I understand it even if the feedstock is completely dry when processing begins there is H20 generated within the reaction. This water is what reacts with the catalyst to form soaps, is that correct?

So has anyone ever looked at pumping the oil through a side tank/container filled with something like a molecular sieve like here: http://www.bio.umass.edu/microscopy/mol_sieves.htm
to remove the water, or at least reduce it, while still processing?

Sort of like an inline filter.

Strikes me that would stop soaps forming and make finishing easier...

Thoughts???

[Rotary-Motion]

i guess the tank themselves could generate condensation which would drop water in the mix abit

[1958steveflying]

An idea for debate   

If its bo11ocks just ignore me, i'm still learning

As I understand it even if the feedstock is completely dry when processing begins there is H20 generated within the reaction. This water is what reacts with the catalyst to form soaps, is that correct?

So has anyone ever looked at pumping the oil through a side tank/container filled with something like a molecular sieve like here: http://www.bio.umass.edu/microscopy/mol_sieves.htm
to remove the water, or at least reduce it, while still processing?

Sort of like an inline filter.

Strikes me that would stop soaps forming and make finishing easier...

Thoughts???

My understanding (which could easily be wrong)  is that the water is created when mixing Naoh or Koh with Methanol, which is why some have gone over to using ASM which has no water.

[therecklessengineer]

My understanding (which could easily be wrong)  is that the water is created when mixing Naoh or Koh with Methanol, which is why some have gone over to using ASM which has no water.

You're partially right. There's also water generated with the neutralisation of the FFAs. (Acid + Base -> Salt + Water)

So while ASM is a worthwhile improvement, it still doesn't entirely eliminate the water.

[julianf]

So has anyone ever looked at pumping the oil through a side tank/container filled with something like a molecular sieve like here: http://www.bio.umass.edu/microscopy/mol_sieves.htm
to remove the water, or at least reduce it, while still processing?

Im pretty sure (almost certain) that the glycerol molecule is several magnitudes larger than an h2o molecule.

So, the glycerol would have to be removed first.  And that would (probably / possibly) carry a lot of the methanol / water / catalyst with it.

[thewormman]

So if the molecular sieve isn't suitable then something like epsom salts which absorb water maybe?

[1958steveflying]

My understanding (which could easily be wrong)  is that the water is created when mixing Naoh or Koh with Methanol, which is why some have gone over to using ASM which has no water.

You're partially right. There's also water generated with the neutralisation of the FFAs. (Acid + Base -> Salt + Water)

So while ASM is a worthwhile improvement, it still doesn't entirely eliminate the water.

Thanks for that 

[Tony]

Useful information about the FFA water relation, I'll stick that in the wiki somewhere

[Jamesrl]

A good glyc pre-wash of very dry wvo will neutralize a good percentage of FFAs in a batch, then onto ASM as the catalyst and 99% of your problems will disappear.

KISS.

[Tony]

Sounds simple enough, the only caveat with glyc prewash is having to react right after otherwise pipes can get blocked as it settles overnight (even if you're super careful draining the glyc).

[Jamesrl]

Sounds simple enough, the only caveat with glyc prewash is having to react right after otherwise pipes can get blocked as it settles overnight (even if you're super careful draining the glyc).

Very true but being as a tight wad I hate to waste the heat so it's wash, convert and demeth  in a continuous flow for me.

[Tony]

I don't like wasting the heat either, there's a definite logic to that process flow.

[RichardP]

Sounds simple enough, the only caveat with glyc prewash is having to react right after otherwise pipes can get blocked as it settles overnight (even if you're super careful draining the glyc).

Not really true, if the processor is designed right then you should be able to drain the pipework completely and leave no glyc anywhere except in the reactor. Insulate the reactor well and the oil and glyc will stay hot enough so the glyc will not solidify, even if leaving a day or so.

[Tony]

Sounds simple enough, the only caveat with glyc prewash is having to react right after otherwise pipes can get blocked as it settles overnight (even if you're super careful draining the glyc).

Not really true, if the processor is designed right then you should be able to drain the pipework completely and leave no glyc anywhere except in the reactor. Insulate the reactor well and the oil and glyc will stay hot enough so the glyc will not solidify, even if leaving a day or so.

I have to disagree.  I did a Glyc prewash in my hot water tank reactor (fully insulated) and settled and drained, then went back three times over the course of an hour and a half, thinking that would be OK, but the next morning the pipework was blocked.  I guess Glyc settles very slowly from oil vs biodiesel.  But perhaps I was just unlucky?

[julianf]

I have found the same - ive always thought that it probably clings to the sides of the cone.  Somtimes, when its far too cold, i put my 10/90 test flask in the jug of product ive drawn off for testing (to warm it).  The glyc tends to cling to the side of the flask when i take it out (way more then the bio)


When i next rebuild my reactor, im going to have the pump slightly higher than the drain port, so i can leave the port open, and the idea was that it would drain the pump also.  But i realise this probably wont work, as the impellers will still have fluid lurking at their lower edge : (