[Terrapreta] Folke's retort kiln

[Philip Small]

There is no draft in the inner barrel.  It releases wood gas under pressure,
but that is different. No charcoal is retained from the outer sleeve, it is
all sacrificed to drive the retort (inner can). The significance of being
able to crack the smoke to get more H2 and CO is that you get more heat
value to drive the retort than with a less efficient configuration, not that
the process could be used to yield charcoal, a capability which can be
employed in cooking stoves which use the same top-lit gasification-related
principles. (Example <http://www.youtube.com/watch?v=PpozW9039_o>)

I imagine that by the time the retort peaks on gas output that it is past
time to replenish the fuel in the sleeve, so no discrete hot charcoal layer
remains to scrub and crack the tail end of the retort gas, so less efficient
burning occurs, although still quite hot and good potential for keeping
smoke minimized.

On Wed, May 28, 2008 at 9:58 AM, francoise precy <f.precy at hotmail.co.uk>
wrote:

>
> This gets me confused b/c I imagine the draft going down (towards the only
> way out, so there is a downdraft inside that inner barrel), and the flame(s)
> being mostly up albeit outside. Assuming that the pyrolysis starts within at
> the top, is the pyrolysis front on top of the layer of charcoal or
> underneath it?  If it's underneath, then the gases get 'filtered' mostly by
> the biomass / wood etc, not by the charcoal. If the pyrolysis front is on
> top, which doesn't make much sense to me so far, then the gases get filtered
> both by charcoal and by biomass.
>
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