wbd

[willbuild]

opinion seems to be divided weather to do wbd or not.
Those that dont do, is it because not wanting to go over the stoich amount? what happens if you do?

[Jamesrl]

opinion seems to be divided weather to do wbd or not.
Those that dont do, is it because not wanting to go over the stoich amount? what happens if you do?

 HMPEs

[Julian]

opinion seems to be divided weather to do wbd or not.
Those that dont do, is it because not wanting to go over the stoich amount? what happens if you do?

 HMPEs

? ? ? ? ? ? ?

[willbuild]

so if my feedstock has a high tit value, say over 2. it will be more likely to see HMPEs if i do wbd?

[willbuild]

I ask because last batch i did, had a high value.  i did a wbd and the batch had HMPEs

[Chug]

Still lots of folks doing WBD without major issue.

I did a WBD this week as always and although it's cold and it was sloppy whites from another vegger I have no hmpe's, some seem to get a load every time they do WBD, but I dunno why they do. I do get a little if temps stay well below freezing for a few days but that is to be expected, they just sit at the bottom so are easily drained and saved til they melt when weather warms up again.

Apart from a slight loss of yield though some folks who have them showing up above freezing do a WBD and then water wash to remove them.

[Julian]

If you remove too much methanol, the theory is that the reaction will reverse.  All well in theory, but to my knowledge no one seems to have experienced a reverse reaction.

There is a school of thought that says WBD promotes HMPEs and I'd tend to go along with that, but there's also quite strong opposition to the theory.  WBD or not, HMPEs do have a lot to do with feed stock though.

My advise for cold weather bio would be to choose feed stock carefully ... very best liquid oil in cold months.  If you WBD, keep the temperatures and time down, say max of 70 - 75 °C and stop at a couple of drops per second (depends a lot on the efficiency of your demeth).  You will still recover a good amount of methanol, come nowhere near the stoichiometric level to reverse the reaction and reduce the risk of WBD promoting HMPEs.

Somewhere on the wiki there's a chart giving the stoichiometric methanol levels and recoverable volume ... check it out, it takes quite a lot of demething to even come close.

[Jamesrl]

it takes quite a lot of demething to even come close.

Bit of a statement there, I can go beyond stoich in just over an hour, there are too many variables involved.

[Chug]

julian, Quite a few people have told me they have kept going til no more methanol comes out and have no noticeable reversing of reaction, admittedly a clear n bright 3/27, 10/90 or whatever ya pleasure isn't GC testing, but I had a very keen guy from the states on infopop when I  posted my method on there who kept contacting me saying it would reverse the reaction.

He did WBD but in push/pull processor with acid neutralising, his emails became almost obsessive and in the end I got fed up with him and was a bit stern and said summat like, "If you stop feckin preachin and actually try it then I might listen to ya but don't knock it til ya try it." seemed to work coz heard no more for a week or so.
Then I noticed an email from him in my inbox, oh here we go again thinks me, but no he was full of apologies, he had tried WBD and used a phlipid test(don't sell em over here but the US guys swear by em, sort of better than 3/27 but not as good as GC test) and his test showed no reverse reaction, someone else on infopop who did phlipid test also had same result and posted pics of his tests, when I have more time I'll search for em.

[Julian]

I did say earlier in the post it depends on your demeth set up ... I didn't want to repeat my self.

I've heard of beyond the pail, but how do you go beyond stoichiometric?  Cold that be an indication of a reverse reaction?

[Chug]

all I ever got demething til nowt was coming out was extra soap, and there is a good chemical explanation someone suggested for that, but memory fails me at the mo!

Anyway a good way to test for mono or di-glycerides would be to reprocess some bio from a 'WBD til no more meth batch' heat to remove any excess methanol and see ifn there is any glycerin droppin out

[willbuild]

all I ever got demething til nowt was coming out was extra soap, and there is a good chemical explanation someone suggested for that, but memory fails me at the mo!

Anyway a good way to test for mono or di-glycerides would be to reprocess some bio from a 'WBD til no more meth batch' heat to remove any excess methanol and see ifn there is any glycerin droppin out

I did that on the last batch and there was some glycerin fall out, I just put it down to not having drained off all the glycerin properly.

[Chug]

with this test I would leave the bio a day at least to make sure any glyc was settled and removed before re-processing just to be sure,  this is how I did it a few years ago and got no extra glyc.

[Julian]

Chug ... not ignoring you, been out, come back a little hissed, so I'll respond tomorrow.

[Julian]

Chug ... we're in agreement on the reverse reaction, I've never seen one nor heard if anyone who has.  Not quite sure what I'd be looking for, but I've never seen anything untoward when I've demethed excessively.  I'd be interested in seeing the results from the chap in the States.

Where we disagree and have done since I started WBD, is that at high temperatures, I suspect it somehow promotes HMPEs.  I've no idea of the chemistry behind my suspicions or any empirical evidence to back it up, just experience.  Whenever I've WBD at high temperatures in winter I've had an HMPE problem ... may all be a coincidence, but who can say.

Similarly, with water washing.  I'm comportable that we've proved water washing reduces HMPEs and helps cold weather performance, but struggle to know the chemistry behind it.

All I can say is that I've not had a serious HMPE problem the last couple of years having WBDed at low temperatures and water washed.