Kosfeld Fenna Thesis - Flipbook - Page 67
Retort
The stacking technique works like this.
Material is stacked in a dense tower, hollow
from the inside, within the exterior barrel. The
feedstock will be lit from the top. Due to the
barrel’s shape, very little oxygen is in contact
with the 昀椀re, which allows a clean burn.
The 昀氀ame and heat move down until the last
pieces of feedstock are burned.
The load can be more than the amount of fuel
material used for the barrel in the barrel.
Technique, which makes this technique more
ef昀椀cient.
Nevertheless, there is little control in regulating temperature, and because of the open
lid, the amount of oxygen entering the barrel
makes the 昀椀re hot.
Measurements when light 300 degrees and
after 10 min 600-700 degrees.
That changes the structure of the biochar and
the amount of carbon/ash ratio.
It is less clean and more complex to regulate
but much quicker.
One barrel of wood residues stacked burned in
about 45-60min completely down
With this technique the next step is quenching
which is pouring water over the hit and fresh
biochar. In its freshly burned state it is super
combustible and needs to be neutralised/
cooled down with quenching. That way, biochar pores soak in water and don’t allow further combustion.
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