Re: flash carbonization of biomass

[Reedtb2@cs.com]

Dear Paul and Aul:

Paul asked....
> Note:  This refers to the primary combustion of the fuel in the IDD "gasifier" stove.  
>
> AND note to Ron and Tom:  Ron prefers the word "pyrolyzer" ("PIE-row-lie-zer", right?) instead of "gasifier".  I have trouble distinguishing between the two terms.  And the word "gasify" seems more clear to me to be what is the end result, which is the creation of gases from biomass that is converted into charcoal.  Comments please FOR THE LAYMAN usage that will help get usage of whatever it is that we call it.

I have come to appreciate that there are two significantly different forms of gasification:

Pyrolytic gasification, yielding CO, H2, CH4 and many minor comonents AND CHARCOAL (up to ideally 30%

Charcoal gasification (with either CO2 + H2O + excess heat) or air (yielding primarily CO)

These can occur in close proximity or quite far apart with the same results, ie TOTAL GASIFICATION yielding CO + H2 + CH4 (+ of course N2, CO2 and H2O).  

Surprisingly this becomes evident in a thermodynamic equilibrium study which predicts about the right quantities of most of the stable products INCLUDING the charcoal.  (But doesn't predict the minor tars etc.)  This is covered in gory detail in a book we are issuing later this month - look for the announcement.

> And below is my real question:
>
> > Tom Reed wrote:    However, in order to move DOWN to the next layer  [in the pyrolisizer, the low flame ] needs to ignite [the next lower material] and if it is wet it needs additional heat to move down.  Therefore, the wetter the fuel the more charcoal is also burned.  With bone dry wood we get 25% charcoal yield;  with 30% moisture we get 5% charcoal yield.  But the gases for cooking burn remarkably similarly across this range.   
>
> Tom,  I read this to mean that "greener or wetter or lesser quality" fuels will yield the desired gases are about the same, and the only loss is in the reduced yield of charcoal.  (And some people are not interested in the charcoal anyway if we get good heat from the pyrolysis/gasification  process.
> In other words, IF the user is stuck with using wet or higher moisture fuel, then "no big problem" with the pyrolysis/gasification process, assuming acceptance that less charcoal is produced.
>
> OR:  Do NOT make a fire for the purpose of drying the damp fuel for later burning (in a gasifier stove), because the only gain would be a bigger pile of charcoal.
>
> I would think that this is rather important (?).

YOU BET!  
I wouldn't go so far as to recommend that people in low humidity climates like Denver wet their dry wood, but
> up to 25%P may be desirable unless you are in the charcoal production business. 


Glad you asked for the clarification.  I'm planning an essay on the effect of water in wood - when I get it untangled.

TOM REED                     BEF STOVEWORKS


> > TOM REED                           BEF STOVEWORKS