[Stoves] Biomass testing questions

[frank]

Andrew and stovers,
<snip>

>I doubt any free oxygen would leave the char.
>Its true that once the char was held constant at 400C it would stop evolving 
>offgas, so no further compounds containing O would leave but there would 
>still be about 20% of the mass of char that would be less volatile substances 
>containing C, H and O.
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>>and just 
>>C+H+N is left to make the Char. So its the amount of oxygen in biomass
>>that determines the amount of fixed carbon and amount of pyrolyzed gases
>>that will be produced after low temperature lipids and resins have left.
>>- I think?
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>Actually I think it's the ratio of lignin:cellulose:hemicellulose that 
>determines the char yield at any given temperature.
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So complex! I agree we need to group constituents but I am not sure 
lignin, cellulose and hemicellulose are the ones we should go for 
because the tests take a long time and are expensive. We would need to 
add fats, waxes and oils, resins, water soluble polysaccharides, and 
protein to the  hemicellulose, cellulose and lignin that you mention. I 
have done lots of these and suggest we do something else if we can. I am 
thinking after the easily volatile compounds (trouble makers) go off  
(they consist of the fats to resins?)  the rest is based on the oxygen 
in the wood structure.  To get CO, CO2 and H2O we need oxygen so they 
will not be made when the wood oxygen  is used up in an oxygen free 
environment.

I am thinking of a hybrid stove that runs off electricity and biomass to 
use for testing biomass. Fill a  pipe with biomass, cap both ends and 
drill a small hole in one end. Place the pipe in a gasifier stove. Block 
all primary air and purge the stove body with nitrogen. Heat the outside 
of the pipe with hot wire.  The pyrolysis gases form and expand out the 
small hole in the pipe. This replaces the nitrogen to fill stove body 
with highly concentrated combustible gases. The small amount of trouble 
makers will go off first and bypass the secondary as smoke as always. 
Then we will have a concentration of CO (not enough O2 to make CO2) and 
H (not enough O2 to make water) heading to the secondary.  This will 
work as long as there is O2 provided from the fuel structure. We test 
these gases. So like running a hybrid car on gasoline and electricity we 
get more for the buck from biomass using electricity to produce high 
quality combustible gases without air. Perhaps the secondary could be a 
fuel cell. Have no idea how the $ add up.


Leaving tonight to drive to Washington.to ETHOS. Perhaps you will be there?

Regards
Frank

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>>Just still looking for easily obtained measurements that we can use to
>>charatorize the combustion of biomass.
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>I'm still interested in what you come up with.
>
>AJH
>
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-- 
Frank Shields
Soil Control Lab
42 Hangar way
Watsonville, CA  95076
(831) 724-5422 tel
(831) 724-3188 fax
frank at compostlab.com
www.compostlab.com