[Stoves] The Art of Using Grass Bundles in TLUD Stoves

[ajheggie at gmail.com]

[Default] On Thu, 4 Apr 2013 21:52:25 -0600,Ron
<rongretlarson at comcast.net> wrote:

>Julien
>
>   I am quite certain the problem is in your statement:
>
>    "I put the can on top a paint-can lid which blocked off all
>> 
>> primary air."
>
>    It was not Crispin's intent that you operate that way, only that you have full control over the quantity of primary air..  In your run, "primary" air was reaching eventually all the way to the bottom by coming through the secondary air circular gap.  You were always producing CO2, not CO and H2.

Ron and Julien, Even if all the air entering the bottom is choked off
there is enough air in the dried stem to allow pyrolysis and then
combustion of the fresh char, given the heat losses the combustion can
continue at a low temperature and never reach the spontaneous
combustion temperature of the offgas. This is one reason why straw
fires are so difficult to put out. Again because the combustion
temperature is low the products of combustion are CO2, steam and PICs.

As Ron says later generating CO2 ( and steam) at the combustion site
causes dilution of the offgas, gases tend to have a limited range of
mixture in air to support a flame below their spontaneous ignition
temperature, so when diluted the cold "smoke" will not support a flame
nor burn without smoke. IIRC also that Tami suggested sooty PICs were
difficult to burn out once formed.