[Stoves] Pyrolysis: No Air?

[kgharris]

Dean,

Thank you for bringing this up.  I have never really thought about there being a difference between pyrolysis and gasification.  The definition of gasification in Wikipedia, "This is achieved by reacting the material at high temperatures (>700 °C), without combustion, with a controlled amount of oxygen and/or steam", is different from the definition of pyrolysis which is without additional oxygen.  Your statement seems correct according to this.  

As I read further in Wikipedia, there is a section on chemical reactions.  Here there are 5 different processes which the fuel undergoes, pyrolysis being one of those.  This would lead me to believe that pyrolysis is part of the more general process of gasification.  Rather than it being one or the other, a TLUD would include both.  The small amount of added air supports the combustion of a small amount of the gas to produce heat, but that air is soon used up and most of the fuel pyrolyzes without added air.  The combination, including pyrolysis, would be gasification.

I will look further to see if Christa Roth adresses this question in her Micro-gasification manual.  

Kirk
  ----- Original Message ----- 
  From: Dean Still 
  To: Discussion of biomass cooking stoves 
  Sent: Saturday, May 16, 2015 3:50 PM
  Subject: [Stoves] Pyrolysis: No Air?


    1.. Hi All,
  When I look up the word pyrolysis I find the following:
    1.. Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures in the absence of oxygen (or any halogen). It involves the simultaneous change of chemical composition and physical phase, and is irreversible. The word is coined from the Greek-derived elements pyro "fire" and lysis "separating".
    2.. However, I think that folks use it to describe what happens in a TLUD, etc? Isn't that gasification not pyrolysis because of the presence of some air?
  Best,


  Dean


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