[Terrapreta] new address to the simple kiln

[Ron Larson]

Philip and terra preta list members - see below.
  ----- Original Message ----- 
  From: Philip Small 
  To: Ron Larson 
  Cc: folke Günther ; Terra Preta 
  Sent: Tuesday, May 27, 2008 9:44 AM
  Subject: Re: [Terrapreta] new address to the simple kiln


  Ron:

  My understanding is that Folke's design is inverted downdraft (aka top lit updraft) based on how Folke first described the workings of it to the list. 
      [RWL:  I will have to go back to Folke's site and look at his earlier material. 

   It was a very brief reference and perhaps my enthusiasm for TLUD (I caught that from you, actually) caused me to read more into it than Folke intended, but I am pretty sure Folke is top lighting this beast.  I was especially persuaded by the clean burn in the photographs with the size fuel shown.  Clean flame isn't the norm with a bottom lit open can.
      [RWL:  I don't think top lit - because the geometries just don't look right.  But Folke can explain it;  I agree that in a review of the photos, it seems like it could have been top lit.  However, I do think it valuable to not top light in this configuration.  One loses some char (so far unkown), but gains a lot in convenience.  I will try some experiments myself - especially to see if there is an advantage also in windy conditions]

  Folke's design is pioneering in its simplicity and effectiveness.  It deserves to be extensively promoted.  I wrote it up this weekend into a FAQ I am working on with some others on the list.  (Ron, please let me know if the explanation of how gasification works in this context is correct):  
      [RWL:  To start, I prefer the word pyrolysis over gasification.  Those who are gasifying strive for minimum char at the end.  Lots of similarities, but on this list, "gasifiers" give the wrong connotation. 
       I agree with Sean in his criticism of some of your next comments.  The main point is that CO appears first at the pyrolysis front and there is not enough O2 to go the next step to CO2.  I am not sure of the chemistry behind H2 production, but agree with Sean (subsequent e-mail) that it isn't water-splitting.  
      The key to successful pyrolysis (unlike combustion) is careful control of the primary air - and I believe Folke is not using that with his outer biomass supply - only the inner supply.  The convenience factor potentially over-rides the advantages of control of primary air supply - but I would hope that this list can still be demonstrate the advantages of control over air flow in this geometry (which I think combines primary and secondary air).

  2.05 Isn't making a lot of smoke kind of un-neighborly?
      [RWL:  Philip:  what is this section 2.05 part of??]
  <snip>
   Uniformity is one reason that colliers will routinely use coppiced hardwoods. 

       [RWL:  Philip - I found this link quite interesting - and I went off to several hours of googling.  Thanks.  I learned the meaning of "turve", "flipe", "motty peg" and many other strange words.   I have concluded that the colliers of several  hundred (and more) years back never had a means of flaring - only venting.] 

      I learned however, that our charcoaling predecessors had laws covering what could be turned into charcoal ("col" at first) - it could only be from trees that were being coppiced - and only a few trees were needed to supply lumber for housing, etc.   At one time, most trees were being used for charcoal - via coppicing.  

       I also learned that the Saint protecting charcoal makers is St. Alexander (one of perhaps a hundred St. Alexanders.  This saint was from the third century - both a charcoal maker and a philosopher!).  Save out August 11. 

  (all this because of this one link!!)

    Ron

  <snip the rest>
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