Prewash gelled

[CanidrivE]

Hi all
As you may have read on other thread, I now have more methanol and started a new batch when I picked up 215 ltr of WVO, from the usual couple of chippies, poured it all in as I wanted to get rid of the cubes etc and drained out the over fill of 15ltr.
Heated the stuff up and added the stage 2 glycerol from my last batch, run pump, etc, etc, so far, all as normal, until I went to drain out the glycerol, it had gelled, cleared it, back after 1 hour, gelled again, cleared it, waited, gelled again
Took out 1 cube of gell / oil + 1 large bucket, of which most went back in again today to make B100.. Reactor is running as I type this.

Any one else had the same problem of the pre wash glycerol gelling like mad ?

Dave

[dgs]

If it is glycerol derived from sodium it can do this when it uses its methanol during the pre-wash.  There is an enormous difference in the physical state between it having meth and no meth. I've even seen potassium glycerol do this.

[CanidrivE]

Hi dgs. Dave1

Yes my stage 2 glycerol is used for the prewash and is derived from sodium "NaOH"
I don't mind it too much happening to me as I can clear my reactor quite easy, bit of an AAAhh, but it can be done and you have seen what I produce.

So, the question would be for others that may encounter this gelling and myself as for it not to happen again, (if possible) what advice could you give, should we add some more meth to the glycerol before adding it to the reactor or some thing completely different ?

Dave 2

[Vijay]

Could it be water in the oil??

[dgs]

Hi dgs. Dave1

Yes my stage 2 glycerol is used for the prewash and is derived from sodium "NaOH"
I don't mind it too much happening to me as I can clear my reactor quite easy, bit of an AAAhh, but it can be done and you have seen what I produce.

So, the question would be for others that may encounter this gelling and myself as for it not to happen again, (if possible) what advice could you give, should we add some more meth to the glycerol before adding it to the reactor or some thing completely different ?

Dave 2

I would say that it is a little counter-productive to use more methanol just to stop the glycerol gelling.

Use a 50/50 mix of Sodium and Potassium, you get the best of both.

[CanidrivE]

Hi Vijay,  water in the oil ? I have been getting oil from here for a long long time, and it has always been dry, BUT ! some water could of creep in.

Dave1, don't have any KOH "Potassium or pot ash".   IF I could get some, Would I mix it some thing like the following, my mix is based on 1200grms

600grms, NaOH + 600 grm X 1.7 KOH to come back up to the same (caustic base)

Dave2

[countrypaul]

How much KOH to use instead of NaOH will depend on it purity (and whether the impurity is NaOH!). Assuming the impurity is not NaOH but the KOH is only 90% pure then you would need 600*56/(40 *0.9).  (Molecular weight of KOH is 56, that of NaOH is 40). So 930g - slightly less than 1.7 x 600g (1020g), but KOH is supposedly more forgiving so using a little extra should not give you major problems. KOH soap can take significantly longer to drop out, so if you usually allow the glyc to settle out then it could take somewhat longer to finish settling.

[dgs]

Just divide your batch volume in half. For the half with KOH use 8gms/litre. For the half with NaOH use 5gms/litre. Dissolve the KOH first which will give you warm methoxide so the Sodium (when added) will dissolve a lot quicker.