Winter HMPE meltdown

[RobPerrie]

well, im just emptying a batch i made about 6 weeks ago into cubies, this was a mixture of fats, but mostly peanut oil , my god, i have a big load of HMPE's or whatever, i reckon 40 litres of the stuff, luckily this is going to spain to get filtered and used...

will post pic

im in the process of making another batch, but no experiment as yet, just the usual with 100% rapeseed, usual 180, titless, clyc wash, 24.5l meths, 760 of sodium,

now waiting for the clyc to drop, 8 hrs at least, but have 2.5 dropout, 10/90, so mixing ready to go 7L,meth and 270 of sodium

will drop most clyc tonight, then the remainder in the moring, before i run up again..

[Chug]

I've got no proof or logic as to why, but I'm sure high de-meth temperatures encourage the formation of HMPE's.

Well I won't be doing another WBD for a while. It was done mainly to test the speed / efficiency of the new coil in tank condensor.

Have none of the proper chemists put up any theories? I was trying to think and Google round it earlier and the best I could arrive at was:

WBD upsets the reaction equilibrium, which skews the equal isomer balance of cis and trans unsaturated alkyl isomers present in the bio towards the trans type, which have a higher melting point than cis type.
But that happens with hydrogenation, whereas during WBD the bio gets pumped full of air which is the opposite....I'm out!

Can you elaborate on wbd upsetting the equilibrium please? what do you mean by this?

and how would a wbd batch get pumped full of air?

[Tony]

Presumably upsets it because the Methanol is removed while the catalyst is still present.

[Chug]

ok, I understand that theory of no meth left so catalyst starts attacking the bio but maybe what I should have asked is what is this equilibrium?
 
and is there an equal isomer balance of cis and trans unsaturated alkyl isomers present in the bio

[Glycer-rides]

I've got no proof or logic as to why, but I'm sure high de-meth temperatures encourage the formation of HMPE's.

Well I won't be doing another WBD for a while. It was done mainly to test the speed / efficiency of the new coil in tank condensor.

Have none of the proper chemists put up any theories? I was trying to think and Google round it earlier and the best I could arrive at was:

WBD upsets the reaction equilibrium, which skews the equal isomer balance of cis and trans unsaturated alkyl isomers present in the bio towards the trans type, which have a higher melting point than cis type.
But that happens with hydrogenation, whereas during WBD the bio gets pumped full of air which is the opposite....I'm out!

Can you elaborate on wbd upsetting the equilibrium please? what do you mean by this?

and how would a wbd batch get pumped full of air?

Meth removed = possible reverse reaction is what I meant.

I run a venturi on demeth, that's where the air's introduced.

They were just some ideas, so one for chemists like I said.

[Chug]

Aha I see it was thrown up possibility/theory ...sorry

[1958steveflying]

I've had HMPE's (if that's what they really are) after very thorough mist washing, but they have only occurred at very low temps (I guess -5 deg and worst).    PF, do you think that what's dropping out at higher temps are different to what's dropping out at very low temps.

 Mate I think maybe yours is at a much lower temp than others because you do tend to speed wash... what I mean by that is not worry too much about settling times which means you drain of a fair bit of milkier stuff with each lot of water, lowering your yield slightly. Could this milkier stuff ( ie: the last bit that wants to split ) be what turns out to be the higher temp Hmpe's in the finished Bio. 

[db]

In the colder months like now I stop recovering methanol and instead prefer to 5% pre-wash, drain glycerol, bubble and settle as I find this reduces hmpe's. I've no idea why but it's significantly better I've noticed.