Reaction slowed by excess biodiesel?

[julianf]

I have a batch on at the moment, which, again, isnt going swimmingly...

For reasons too tedious to write out in full, the process started with 340 ltrs, of which probably about 140 ltrs was fully demethed bio.

I mixed up the chem for 150 ltrs (about 75% of the unreacted oil)

(30 ltrs meth / 750g sodium)

...but now not a lot is happening quickly.


My hypothesis -

Either -

Ive f@#ked it up again, or...

The batch is now on the large side for my currently connected single 60lpm pump, coupled with for every molecule of veg, there's not far off the same volume of bio getting in the way?


Ive not notice this so much on S2 reactions before, im guessing, as a lot of the unused meth is still present, however, on this one, there's not much meth given the total physical volume.



So, what do you think?  How long do you think i should run the job for until i start getting upset?

[nigelb]

I'm surprised that someone with your experince would put so much demethed bio in a batch for processing. You havn't explained why you've done that.  I imagine that some of the catalyst has been used up in over processing that part of the solution.

Is there a reason why you didn't react a batch of 200lts?

[Head Womble]

I'd say the demethed bio has sucked up a large amount of the meths, and this is what's slowing things down.

[nigelb]

Meths/catalyst....its all the same when it's being used up by something else in the reactor... ie 140lts of demethed bio!

[julianf]

The batch is on demeth now.

S1 only converted 10% more of the total volume.
S2 was dosed for the remaining, and the resultant conversion was 85%.
Aprox 40 ltrs of glycerol out after S2.

S3 was dosed for the last 15%, and ive set it to demeth.

Im quite scared of jelly at this point, so demethed a sample on the cooker.  The sample has cooled to about 40c now, and looking a bit odd, but then i never normally demeth small samples.

I have about 50mm in the bottom of a jar.  The lowest (!) 10mm is crystal, and the upper section is hazy / whispy.

On the single jelly batch that i brewed before last week, i recall the jelly lurking lower down.  And last weeks meddling resulted in some samples that had jelly covered in a clear upper layer.