[Stoves] corn cobs and char?

[Ronal W. Larson]

List, Tom etal:

    Thanks for all the inputs.  Any others on corn cobs would still be potentially helpful.  

   My interest is only in the pyrolysis of such (for biochar production in a simple stove reasons, of course), and (as noted by many below) their low energy density makes pyrolysis difficult in TLUD.  Re corncobs themselves in the US, this cite I found helpful:
      http://renewables.morris.umn.edu/biomass/documents/Zych-TheViabilityOfCornCobsAsABioenergyFeedstock.pdf

   This site 
        http://www.ars.usda.gov/is/np/alwayssomethingnew/Waste11.pdf
says that globally there are 35 Gt cobs per year - which would make about as much available as char as total annual fossil emissions. - of 7-8 Gt C (very few of them now being used for anything).   But this sounds way too high, but 35 million tons sounds too low.  I have read 15% of a corn plant is in the cob, and annual production is approaching 1 Gt C.  Anyone an expert on corn?  In any case, corn os the world's largest grain crop - in both hectares and tons now, I believe - so their should be some cooking application for cobs somewhere

  This site has a good 2012 paper on corn by Zhang      thescipub.com/pdf/10.3844/ajbbsp.2012.44.53


   The reason for asking about cobs is not only that they are pretty widely available,  but they are not a bad size and shape (especially compared to rice husks, which get a lot of attention in the stove world)

     I am looking for reasons to drop the corn cob thread, but not yet found it.


   Might as well design for the EPA testing protocol  (5 kg water,  45 minute simmer??,  etc).  Can anyone supply that  (in published form preferably) in terms of anticipated energy need to the pot.?  After which  we can figure 30-40% (or different Tiers) stove efficiency.    Then we can go to container sizes, number of fuel switches per test, etc.

  The first site above says about 5 GJ/m3 for corncobs (and 12 for wood pellets), so  (forgetting reloading)  the fuel volume needs to be about 2.4 times larger than one with pellets that is also a char-producer. But down draft also allows reloading, not possible with TLUDs.  And (maybe) we can avoid a larger fuel container and achieve lower first cost with BLDD.
   

  Anyone been thinking along these (corn or BLDD) lines? 

   I have in mind a downdraft design that I think can overcome the space and several other problems with TLUDs.   Nothing much on paper, but I'd be glad to discuss the BLDD topic with anyone - in an open source context.   This is NOT dependent on corn cobs, but came out of thinking about cobs.



Ron 


On Aug 14, 2013, at 8:34 AM, "Tom Miles" <tmiles at trmiles.com> wrote:

> It seems to me that we have seen cobs burned with wood fuels in stoves for
> several years, especially in Latin America.  
> 
> A challenge with crop residues is that they have enough air in the stalks,
> cobs and stems to barely support combustion so they tend to smolder rather
> than burn. A little wood provides enough of a pilot flame to keep the
> combustible gases ignited.  
> 
> Tom
> 
> 
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