HMPEs or monoglycerides?

[Tony]

So we have a nice HMPEs page, but recent findings might suggest this page is not factually correct.

http://www.biopowered.co.uk/wiki/High_Melt_Point_Esters_%28HMPE%29

I think we might need to revisit this.

We know:

- that they give cloudy meth in a 3/27 test
- they form emulsions with water
- water washing seems to prevent it
- reprocessing it as part of another batch (while treating it as an inert component) produces fuel that doesn't have high melt components anymore
- WBD might(?) promote their formation in winter

The suggestion is that monoglycerides are the culprit as they have an elevated melt point, give the cloudyness to 3/27 and would wash out from a batch, which seems to fit the evidence.

Surely if they were just high melt FAME then reprocessing would not in any way shorten or dehydrogenate the fatty acids chains to reduce the melt point, so this seems the more likely explanation.

So should we rewrite the HMPEs page to be a "High melt point components" or "surviving winter" page, mentioning both feedstock related High Melt Point Esters (from Palm oil) and monoglycerides (from incomplete reaction or partial back-reaction)?

[nathanrobo]

I think you are right!  The high melting or waxy stuff seems to have different properties with different brewers.  The commonality seems to be it's appearance, consistency and the fact that they appear in the winter.

At some point we'll get a definitive answer as to what the stuff is - probably more than one thing.  In the meantime describing it, along with it's typical characteristics and methods for dealing with it would be a sensible way forward.

[Julian]

I think you are right!  The high melting or waxy stuff seems to have different properties with different brewers.  The commonality seems to be it's appearance, consistency and the fact that they appear in the winter.

At some point we'll get a definitive answer as to what the stuff is - probably more than one thing.  In the meantime describing it, along with it's typical characteristics and methods for dealing with it would be a sensible way forward.

I'd go along with that train of thought.  I've wondered for some time if we are all seeing the same thing, but giving what we see we give convenient label.

[1958steveflying]

So we have a nice HMPEs page, but recent findings might suggest this page is not factually correct.

http://www.biopowered.co.uk/wiki/High_Melt_Point_Esters_%28HMPE%29

I think we might need to revisit this.

We know:

- water washing seems to prevent it

Whatever I pull out with my Fuge at or around zero c is the same as Nathan pulls out, however he water washes and I do not. what we both pull out fits what has been called Hmpe's so I cannot be convinced that water washing does in all cases prevent it.

Having said that I would not be certain that what we pull out would cause a vehicle to break down unless the temp remained below zero for a sustained period.

[Julian]

 I think Tony's remark about water washing preventing "them" might be little enthusiastic.  In all the tests I did what seemed obvious was that washing reduced but didn't prevent them.

There are folk who claim washing prevents the, based on experience, but that's a little like trying to prove a negative, especially as we are fairly sure they are feedstock dependant.

[nathanrobo]

Did you see the pic I posted yesterday?  It kinda worried me a bit coz this time there was visual evidence of the stuff (unusual) - Could be be the longer duration in the cold or something else?

[julianf]

I think Tony's remark about water washing preventing "them" might be little enthusiastic.  In all the tests I did what seemed obvious was that washing reduced but didn't prevent them.

There are folk who claim washing prevents the, based on experience, but that's a little like trying to prove a negative, especially as we are fairly sure they are feedstock dependant.

If they were mono's / di's as a result of reverse reaction, then -

Water washing at a low enough temperature where the reactions would be slowed would not create them &
Water washing may then remove them, if they were formed.


It is strange how some people have so much issue with them, but others have none.

Currently, im removing the glyc at the end of s1 and then dosing s2 / going to bed / opening the venturi to vent to atmosphere all at the same time.  (ie part batch WBD, if that makes sense?)

I leave the fuel in a settling drum for weeks though, so maybe i create them, and they form and drop with the soaps?

[Tony]

That's certainly what happens with mine, it's a layer of cream over the settled (and usually solid) soaps.  I top skim the bio through the drywash tower then pour the rest into another drum, accumulating this creamy stuff - which is what I used with the successful reprocess batch.

Even after drywashing I store the fuel in a 205l drum and if the temp drops sometimes I get more at the bottom of that, from the previously top-skimmed stuff.

[nathanrobo]

The only time I've been able to see them in the fuel is the last batch that had sat for four months prior to filtering.  Normally they are not visible in the fuel - the bio looks visually really good and ready for use, yet they appear after filtering. 

Does this suggest that there is a high distribution of very fine wax elements with a similar SG to BD which conglomerate whilst being spun which makes them drop out. 

[Greenchef]

Right then, here's a different take for you. I have only experienced this gel like cloud referred to as hmpes once in my production of bio. It happened this winter when using 50% rape oil and 50% KCT (soya.)

My usual feed stock would be mostly soya and some palm, which are both not seeds! I am sure that this gel like cloud is actual mucilaginous fiber. www.organicannie.com/Gel%20Seeds.pdf This link give a brief description.

As i have stated before we inadvertently us this in cooking to form emulsions in the forum of mustard seed and rape seed oil.

It is massively water absorbing, and in its raw refined state is a gel like substance used to aid digestion in oriental cooking.

Being a gel it would melt when heated and reform when cold.

Could it not be that water washing would help to remove this by flushing it out? More to the point could seed based oil feed stock be the problem?

[Tony]

What is curious is why would making biodiesel (without washing, so no water present) from liquid feedstocks result in some solids?  To me this suggests a chemical change rather than contaminants.

But, that said, it seems pretty certain there are several ways to end up with fuel waxing, and mucilaginous fibre may be one of them.  The problem is distinguishing between them.

Is there any way to identify mucilaginous fibre?  I'm thinking effect of acid, solubility in various solvents etc.

[Julian]

Right then, here's a different take for you. I have only experienced this gel like cloud referred to as hmpes once in my production of bio. It happened this winter when using 50% rape oil and 50% KCT (soya.)

My usual feed stock would be mostly soya and some palm, which are both not seeds! I am sure that this gel like cloud is actual mucilaginous fiber. www.organicannie.com/Gel%20Seeds.pdf This link give a brief description.

As i have stated before we inadvertently us this in cooking to form emulsions in the forum of mustard seed and rape seed oil.

It is massively water absorbing, and in its raw refined state is a gel like substance used to aid digestion in oriental cooking.

Being a gel it would melt when heated and reform when cold.

Could it not be that water washing would help to remove this by flushing it out? More to the point could seed based oil feed stock be the problem?

Hmm, interesting theory.  I can't start to understand the chemistry involved, but I have to admit the years when I experienced the biggest problems with "HMPEs" was when just about all my oil was coming from one supplier and they used exclusively non GM rape from Agri.

Trouble is it's often difficult to know the provenance of all the oil you collect.

I still have the redundant freezer and a new controller, if suitable samples can be obtained.

[julianf]

What is curious is why would making biodiesel (without washing, so no water present) from liquid feedstocks result in some solids?

I posted a link up a while back (cant post it again, as who knows where it is!) that had the melting points of a triglyceride, and then the di, and mono.

IIRC the di and mono had really significantly higher melting points than the tri.

[Greenchef]

Tony, The Solids or gel if you like can only occur if moisture is present the fibres we are talking about are tiny but they collectively have massive ability to absorb water (possibly from the air, condensation in cubies and containers is quite common.) hence the gel or solids forming.

This is all guess work based on observation of bio production and my own experiences with gels and emulsification agents used in modern cooking. I know for a fact that rape seed oil emulsifies very easily where as olive oil dose not. This is down to the presence of mucilaginous fibers from the rape seeds and their ability to retain water.

Probably all thoughts of an idiot but there they are!

Chris

[Tony]

I know for a fact that rape seed oil emulsifies very easily where as olive oil dose not. This is down to the presence of mucilaginous fibers from the rape seeds and their ability to retain water.

Very interesting, I honestly did not know there was a difference!