Dear Tom,
As I work, mostly alone, I don't have frequent terminological problems:)
As a pre and post T-LUDite, I go with the flow, up or down, forced or
natural, fixed or moving.
As a technician I welcome a characterization of the T-LUD gasses but
would add that the T-LUD bed temperatures can be pushed as low 480C. At
these temperatures I was able to sustain a completely blue flame. It
would be good to tease out the differences in gas composition , as well
as it corresponding char characterization, across the full temperature
range.
List-ening in,
Alex
On 10/12/2011 8:34 AM, Thomas Reed wrote:
Dear Gasification list
Well defined terminology is fundamental to a discussion of the science and praxis of any
subject. I am proposing two new words for the different gases we make. They will help
clarify discussions we have and will have here at the "Discussion of biomass
pyrolysis and gasification " list.
These are proposals, and I hope they will spark a discussion of this and other
terms that have grown up helter skelter. We welcome alternate suggestions.
<><><>
WOODGAS is a term I have been using for thirty years. In German it is Holzgaz,
an exact translation, holz being the German name for wood. It refers to the
gas made in gasifiers that completely convert wood to combustible gas, often
for use in IC engines. It is the name of our website where we sell books on
gasification and Woodgas cookstoves.
For this discussion and others, I propose the abbreviation "W-Gas".
Wood is composed of ~20% lignin and ~80% cellulose (cellulose plus
hemicellulose). On heating in the absence of air, the cellulose produces mostly
the Woodgas, while the lignin is converted to charcoal. Since the lignin is
the principal source of tars in Woodgas (up to 2% by weight of the wood) tar
removal is a very big problem for using W-gas in engInes.
<><><><>
More recently (starting in 1985) we have developed a new form of "PYROLYTIC
gasification" in which air is admitted to a dense bed of wood pellets, chips or sticks,
forming an auto pyrolysis zone passing up or down through the bed and burning a small fraction of
the pyrolysis gas to convert the remaining cellulose to a combustible gas which can be used for
cookstoves and charcoal generation. Paul Anderson has dubbed the stoves "TLUD, Toplit
Updraft" stoves.
The TLUD gas composition has not been well characterized yet, but I'm hoping someone
will do so soon (possibly me). ( In an attempt to measure tar, I condensed about 1/2
% of a non sticky grey soot in a four foot X 4" galvanized stove pipe.).
I propose the name "P-Gas" for the gas made from mostly the cellulose in this
process.
(Incidentally, the charcoal made in this 600-800C process is significantly
different from conventional charcoal, and has much less tar and much higher
absorption properties. It could be called PG- (PYROLYTIC gasification)
charcoal. )
<><><>
I hope that this will spark a discussion of this and other terminology used in
this list. Since Tom Miles is the moderator of this list, I'd like to appoint
him as the final arbiter of terminology for the list.
Dr Thomas B Reed
The Biomass Energy Foundation
www.Woodgas.com
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