[Stoves] Biomass testing questions
frank at compostlab.com
Sun Jan 18 14:35:02 CST 2009
>On Fri, 16 Jan 2009 14:51:32 -0800, frank wrote:
>>1) If I test the char for carbon and nitrogen can I assume the rest to
>>be hydrogen and that there is no oxygen left in the char?
>No if there's still hydrogen with the char I'd expect the tarry bits
>that this hydrogen is part of also to include oxygen at this low
>>3) Can we (should we) assume most all ash free biomass to have 6%
>On the basis that most biomass takes the approximate form C6H7O3
>shouldn't that be 7.5%?
>>So I can determine the amount of hydrogen in the volatile HO
>>fraction (subtract from that in the char) and then have both the Oxygen
>>and hydrogen values?
>You've lost me there, isn't water the only volatile component that
>just consisted of H and O with no carbon involved?
That was not very clear. The water is gone with the 105 deg drying
temperature before I start char making. I am thinking the fixed char is
the carbon left after the wood oxygen has gone off taking some carbon as
CO and CO2 along with it. So when all the wood oxygen is used up the
pyrolysis gases stop and left is fixed carbon. (??) Coal is done at 950
deg but I think for our purpose we should use the 400 deg temp for
making fixed C+H+N = char.
I am thinking I can wrap a metal pipe with heating element and
insulation. Have a slow flow of N passing through. Read CO, CO2 and O2
at the exit. Fill with known amount of oven dry fuel (105 - 110 deg. C)
and purge with nitrogen until the Oxygen level is zero. Add heat slowly
to 400 deg. C and monitor (plot) the CO and CO2 readings and make sure
there is no leaks by the O2 at zero. (unless free O2 comes off the
fuel?). As it stays at 400 deg c the CO and CO2 should go down to zero
meaning all the wood O2 has left, no more pyrolysed gases, 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? I can measure the O2 (calculate from CO + CO2), and have the
equipment to measure carbon and nitrogen and H is left. But if there is
still Oxygen left in the char I am on to plan B.
Just still looking for easily obtained measurements that we can use to
charatorize the combustion of biomass.
Soil Control Lab
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frank at compostlab.com
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