[Stoves] Charcoal making retort that makes use of the wood gas produced

[AJH]

On Wed, 22 Aug 2007 16:55:24 -0700 (PDT), Charlie Sellers wrote:

>With this set up, what procedure should I use to extract a large volume of decent gas (art projects don't need clean gas since they have a short life) so I can run several lamps (wavering flames so no huge volume for each) or flare all the gas using a simpler burner (so that we do not produce the smoke usually associated with charcoal making) - 

Charlie I think you've identified the problems you're encountering in
flaring the gas, you have a simple updraught arrangement and the gas
being produced is diluted by the combustion products from your
"starter fuel charge".

The most straightforward way to demonstrate a good flarable gas and
make charcoal is to use the top lit updraught layout, as in the camp
stove. Here the heat is provided by a very small amount of air rising
up through a column of (very) dry, small fuel wood and burning at the
interface of a descending fire front and the fresh wood fuel. This
results in a rich fuel gas (pyrolysis offgas) rising up through the
char layer. This pyrolysis offgas can then be led off to your
demonstration flare, though I think you should attempt to keep the
distances short and well insulated as it isn't a true gaseous mixture,
more a sol of tarry droplets in a gas mixture.

If you are stuck with your present arrangement (which sounds more like
a kiln than a retort) then try and separate the "starter wood fuel"
from the"main biomass load" by making the container for the main
biomass load a separate airtight container ( true retort) with a vent
pipe opened to atmosphere. Use very dry biomass and expect to vary the
pipe outlet diameter to match the gas velocity with the flames speed,
beware of pressurising the container!

AJH