Recovering a jelly batch
If too much catalyst is added to a batch, the result is a wobbly biodiesel jelly. But don't panic - it's fixable!
The jelly effect is usually noticed
- after the glycerol has been dropped and demething started, as the methanol content keeps it liquid otherwise
- when water is introduced to do a water prewash
- when draining the glycerol (very thin, keeps coming - the glycerol is held in suspension by the jelly)
The steps to fix this are:
- If the batch has already cooled, heat back to 55-60C. This should make most (if not all) of the jelly liquid again.
- Add back any reclaimed methanol and mix using the pump. Take regular samples and leave to cool - keep going until these cooled samples remain liquid without signs of jelly. Add more methanol if necessary.
- If already removed from the batch, add back the glycerol.
- Do a generous water prewash (EG add 7% water, mixing well with the pump).
- Drop the glycerol, which will take a lot of the excess soap with it.
- Demeth the batch as normal - but keep a close eye on it, because as the methanol content reduces, it may start to foam up. If the foam reaches the condenser you'll end up with a right mess (foam spewing from vents!)
- Settle/air bubble the batch as normal. You'll have some extra soap drop out but the yield won't be greatly reduced, and it shouldn't turn to jelly on cooling.
- Finally, enjoy your recovered bio.
Tony 16:39, 9 May 2011 (BST)