Recovering a jelly batch

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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:

  1. If the batch has already cooled, heat back to 55-60C. This should make most (if not all) of the jelly liquid again.
  2. 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.
  3. If already removed from the batch, add back the glycerol.
  4. Do a generous water prewash (EG add 7% water, mixing well with the pump).
  5. Drop the glycerol, which will take a lot of the excess soap with it.
  6. 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!)
  7. 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.
  8. Finally, enjoy your recovered bio.

See also

Tony 16:39, 9 May 2011 (BST)