Art,
Have you got any data on char cation exchange capacity?
Alex
On 17/06/2013 2:23 PM, Art Donnelly wrote:
Hi all,
I want to provide some information on the ability of ND TLUDs to
utilize coconut waste as an input material as well as comment on the
relationship between the temp. at which char is produced and the
issues of yield and surface area.
Coconut shell and coir burn very well and very cleanly in the ND
Estufa Finca TLUD.
Obviously the dense shell is preferred for it's longer burning time,
but the mix gives us a great biochar, which the nursery men seem to
like. Perhaps this works well in this stove because we use more
secondary air than I see in some other similar stoves? As with other
fuels, we can continue to add this material to the stove as it burns,
to extend cooking time. This strategy does result in a lower yield of
char, than the straight load and burn to completion method.
When we load the stove, light it and run it until the flame color
changes we routinely yield 30-33% of the the original dry weight of
the input material as biochar.
I monitor both our Estufa Finca stoves and 55-gallon drum J-RO kilns
with a K-type digital probe thermometer. The stoves pyrolysis front
produces char between 500-700c the J-RO between 600-800c. I have had
Hugh McLaughlin characterize approx. 14 samples of different material
made in these and material processed in retorts with a temperature not
exceeding 450c. The biochar from the TLUD type devices all have
greater available surface area than the same materials produced at the
lower temperature range. Wood, bamboo and coconut shell all come in
around 400m2/g. Close to the low end for activated charcoal. These
chars are giving us good results in the soil when mixed with compost
or inoculated with EM. The reduction in tars in the higher temp. chars
is a plus.
Art.
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