[Terrapreta] torrified wood vs. charcoal

[info at biorealis.com]

Hi Rob,

Thanks for the reply to my earlier question. No, the "stove" (or, 
maybe more accurately, 'retort') I'm envisioning is not an open fire. 
It is an externally heated closed chamber filled with biomass, 
functionally similar to one of sketches shown on Richard Boyt's 
pyrolysis page -- but with a much lower external heating temperature. 
(e.g. 400C). There is no combustion happening inside the chamber. 
Only biomass heated by the external source. What could one expect to 
come out of a gas vent connected to this retort?

See sketches here: 
http://www.crest.org/discussiongroups/resources/stoves/Boyt/pyrolysis/pyrolysis.html

What originally caught my attention -- and prompted my question -- 
was your comment:

 >When you heat up biomass to around 280C it goes
 >into an exothermic reaction (begins to give off heat)
 >and the temperature jumps to around 400C.

Thanks again,

Bob Crosby


The stove you describe in the last part is just an open fire from what I can
make out. If you start a fire and add fuel to the top and have air flow from
the bottom you just doing complete combustion (Reduction to ash) and you
will always have lost energy as the moisture will make your gas very wet.
When all the moisture is driven off and you start burning the off gases have
finished burning then you could in theory quench the char but it sound
dangerous!


 > What if it is *not* a gasification stove, but a completely closed
 > (except for a vent to release the gases generated within) vessel
 > filled with biomass and heated to 400 degC? What could I expect to
 > get out of such a reactor?