[Terrapreta] Strong warning against "simple" charcoal kilns

[Peter Read]

Don't really want to get drawn into this too much, but surely Sean's problem can be solved by letting in some secondary air near the top of the outer barrel, as is done in efficient closed combustion stoves.  Maybe clap on a lid with chimney over the top, to maintain high enough temperature for methane combustion.
Peter
  ----- Original Message ----- 
  From: Sean K. Barry 
  To: Kurt Treutlein 
  Cc: terrapreta 
  Sent: Monday, April 28, 2008 5:23 PM
  Subject: Re: [Terrapreta] Strong warning against "simple" charcoal kilns


  Hi Kurt,

  I'm sorry about the verbiage that I have so generously trimmed for you now.  You people want to over-simplify this issue, I think.  The Methane-CH4 ejecting from a charcoal forming pyrolysis reaction does not necessarily all burn up, as you suggest.  It can't.  "Open-air" reduction of H2 and CO in the "producer gas" will use as much as 5 times the amount of oxygen as the CH4 will BEFORE the CH4 will reduce.

  When the ignition temperature for CO and H2 has been reached AND there is a steady supply of enough Oxygen, then ...

  10CO + 10H2 + 10O2 => 10CO2 + 10H2O, first!

  Then, AFTER THIS, if there is any oxygen is left and if the temperature is high enough

  CH4 + 2O2 => CO2 + 2H2O

  The likelihood of there being enough oxygen at 19% concentration in air and at atmospheric pressures, is, I think, quite low after the CO and H2 burn (FIRST!).

  Regards,

  SKB


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