Re: "Formula for Biomass" and Charcoaling....

[Reedtb2@cs.com]

Dear Alex and All:

You wrote...
> Dear Tom,
> My tests on IDD stoves have recorded  fuel temperatures of 600 to 800 
> C depending on primary air (superficial) velocities through the fuel.
> http://www.ikweb.com/enuff/public_html/bigtop/bigtop2.htm 
> show a peak pellet temperature of 800 C when using a blower, which is 
> the temperature as the pyrolysis front passes the thermocouple.
> When using natural draft the corresponding peak is around 600 C.

Not quite.  I get the same results on peak temperature of the pyrolysis front passing through unburned dry fuel.  HOWEVER, the thermocouple is responding to both the temperature of the pellet (probably < 600C since pyrolysis is essentially complete at 450 C) AND the burning gas temperature, possibly a peak of 1500 C, but a very transient flame transferring heat as produced to the pellets for pyrolysis.  

Obviously very little of the charcoal is being burned with a yield of 25% for bone dry fuels.  

It would be interesting to repeat your TC measurements with 25% moisture fuel since it is necessary to burn most of the charcoal so that the flame front can propogate into the wet fuel.  I'll bet the temperature is much higher, since charcoal can burn at 1400C.

It is paradoxical that a wetter fuel sometimes produces higher temperatures, but in conventional downdraft gasifiers you can melt the grate if the fuel is too wet.

As I have said before the pyrolysis/gasification/combustion (PGC) of biomass is significantly harder to understand the atomic energy, since in 20,000 years we have still a lot to learn about biomass PGC, while the atom has been fully comprehended in 100 years.  But few people are trying to understand the fundamentals, so we may have to wait another 100 years for complete clean efficient use of biomass.  

Your pal,         TOM REED             BEF STOVEWORKS



> So according to your guidelines below, I have been producing 
> metallurgical charcoal with natural draft and activated charcoal when 
> I use forced air.
>
> Where is the lab that could give me a complete charcoal appraisal?
>
> Alex