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First Batch Failure

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  • First Batch Failure

    Hi ok so we sent our first batch through our new reactor... reaction was looking good... but now that we have left it to settle it's formed a honey like substance... strange crystaline structures in it... jammed the whole system up good and propper... it won't pump...

    We are using KOH... our oil titrated at 3 grams KOH per liter... 40 liter batch... 7+3 = 10 grams per liter... 90% pure KOH... this in total comes to 440 grams for the batch. 8 liters of methanol...

    We titrated a couple times to make sure...

    I think there was a small amount of water still left in the system. We calibrated the indicator with water... would this have cause this problem? How on gods green earth do we clean it out?

    This is what we've done...

    1. Pre heated oil to 58 degrees
    2. Add Potasium methoxide mixture to oil
    3. Let mix for an hour
    4. Let settle...

    How long should we let it settle?

    It is also possible that our temperature controller was off by quite a large amount... it may have been too cold... does this make a huge diference?

    The mixture was looking good when we started to let it settle... is had changed in texture... was looking thin like diesel... and you could see movement in the liquid as if it was reacting...

    Anyways... any help would be appreciated...

  • #2
    Re: First Batch Failure

    Curious - the process sounds OK - more information is needed on the results - is the whole lot like honey or just the Glycerine?

    What sort of oil was the feedstock?

    I would heat it up again - that should make it liquid again and try re-reacting the results - after you drain off the glycerine.

    Water in the process forms soaps - these are basically invisible until you wash - then it makes the batch more susceptible to emulsions and takes longer to wash.

    Do some mini batches in a one litre bottle to see how much to meth and KOH to use.

    Settling to 90% should happen in an hour.

    Learn your craft with minibatches before tackling a big batch - it gives you a feel for the reaction.

    It is a simple process and the reaction is pretty forgiving. Be patient and take it slowly. Be very gentle with the wash at the start of that process. It will go like orange juice - don't sweat it - just let it go, it can take hours with a gentle mist.

    Good luck,
    Paul
    Brisbane
    80 series TDi with 100K on B100
    2005 Audi A3 TDi B20-B50 60K on BD
    1993 Daihatsu Rocky - B100 20K on BD - all good!

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    • #3
      Re: First Batch Failure

      Procedure sounds fine. I put strong odds on there being substantial water left in the system. From what you wrote about calibration, there was probably heaps of pockets of water just waiting to neutralise your catalyst.

      The crystaline structures may be just unprocessed fat that is congealing in the biodiesel. Heat it up again and let the glycerin (assuming you did get some glycerin) drop out, then tap off the glycerin.

      Any water should drop out with the glycerin as the water and glycerin have an affinity for each other. Then re-do the batch. Just use the same formula for the methoxide as you did for the first batch. Excess KOH is not a real problem, the worst case scenario is losing about 1-2% of the batch to excess soap.

      After this batch you should be - good to go!

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      • #4
        Re: First Batch Failure

        Any chance you can pump into another vessel as a settling tank. Free's your reactor up ready to do another batch as well as prevents problem batches from blocking up your system.
        Joe Morgan
        Brisbane Biodiesel Site Admin
        http://www.brisbanebiodiesel.com

        Searching tips using Google - SVO Dual tank systems
        SVO, Common Rail and Direct Injection - Vehicles converted to Used Cooking Oil

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        • #5
          Re: First Batch Failure

          Hi XCide. Never do your settling in the reactor, always pump your product into a separate settling tank. With the volume your doing a spare, clean 44 should do. If you've had a good reaction and formed almost hard glycerine, like honey from the fridge, that may be a good sign that you've done everything right---except leaving it settle in the reactor.
          darren leonadas
          Senior Member
          Last edited by darren leonadas; 3 July 2006, 03:07 PM.

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