[Gasification] sawdust or shredded paper gasifier on sawdust stove design

[jim mason]

i was just doing a little reading on the drum sawdust stoves often
used in wwII and elsewhere.  the basic idea is packing sawdust into a
drum, with a pipe or taper in the center, which is removed after
packing.  air is introduced in the bottom, which slowly burns the
sawdust cylinder or cone outward, with gases and heat going upward.

see here:

http://listserv.repp.org/pipermail/gasification_listserv.repp.org/2006-January/003682.html

or here with drawing.
http://gasifiers.bioenergylists.org/?q=node/16

or here for a very simple one in mother earth news.
http://www.motherearthnews.com/Green_Home_Building/1974_November_December/How_To_Build_And_Use_A_Sawdust_Stove

or here for the best design i could find
http://sleekfreak.ath.cx:81/3wdev/VITAHTML/SUBLEV/EN1/SAWDSTOV.HTM


given the directional nature of its combustion, such a design is
operating partially as a gasifier.  but the air flow control is a bit
loose so a mandatory reduction zone is not well maintained.

if such a design was modified so that the pipe in the center was
narrow and long (somewhat like the mother earth design), as well as
made out of high temp stainless steel, air passed from one end or the
other would result in a  good separation between combustion and
reduction zones.  and therefore a good gasification process would
happen.

sawdust would still be packed in like the sawdust stove.  shredded
paper would work too.

packing would have to continue during the burn so that the fuel stayed
against the center tube mesh.   such is not trivial, but it likely
easier than fireballing and other off site machine densification
efforts.  maybe a loose pack with a constantly turning short auger at
the top.  new fuel introduced below and packed down enough to keep it
reasonably tight against the central mesh tube.

yes, many questions here.  but it is an interesting design direction
to consider towards the always wonderful imagined goal of having a
paper shredder on your car, insert trash, and start the engine thusly.
 this design would reduce many of the paper processing difficulties
that prevent the easy use of paper trash as fuel.

of course, ash output down the center tube would be high.  and the
mesh might slag up.  the later could be solved with a kalle like
movable sleeve that flushes the slag from the grate (mesh in this
case).  or a mesh tube within a mesh tube, the inside one being turned
by the same shaft that turns the auger.

maybe i should draw a picture . . .

has anyone tried anything like this?

j