[Gasification] W-Gas and P-Gas defined - and redefined

Sun Dec 11 17:53:44 CST 2011

On Sun, Dec 11, 2011 at 11:33 AM, Tom Miles <tmiles at trmiles.com> wrote:
> Useful predictions: gas and char quality
>
>
> I think the chars have been described as similar to the oxidative chars from
> downdraft gasifiers. Is there any consistency with regard to the extent of
> carbonization (% fixed carbon) or other physical or chemical qualities of
> TLUDD chars compared with the downdraft chars? Are there any distinctive
> qualities of TLUD chars from agronomic trials? What do soils and plants
> like/dislike about TLUD chars? Do they have more affinity to chemicals than
> other chars?
>
>

tom, these questions were the motivation for why i made the BEK.  it
was intended to create a testbed for running all these different modes
over the same "reaction vessel volume".  i wanted to see if our
conversation on char types could add in the variables of pyrolysis
process mode, as well as gas take off direction (over made char vs
away from made char) to our usual conversation on top temp, ramp rate
and residence time.

while we made the machine to run these tests, we have yet to find the
time to do the research.  we've had to set this work aside to focus on
our core endeavor of figuring out how to manufacture and support
gasifiers.  this has proven to be harder than email.

i think it would be fairly straight forward to answer these questions,
and get some basic understanding of pyrolysis mode impact on char
types, as well as gas composition.  we just need someone to sign up to
do the work.  we have a BEK sitting at our shop for whoever wants to
come and do the work.   we'll even send it elsewhere to do the work
elsewhere if someone proves they are serious about the research
project.  tom reed, you want another machine in MA?

the project will require some technical skill and familiarity with
instrumentation.  the BEK is also fussy to run and requires all 8 of
your hands to keep it between the lines.  this is not an ease
optimized production machine, but rather a research tool with an
excess of knobs and levers.

i'd really like to get through these basic characterizations of
pyrolysis mode so we can get rid of all the knobs and levers and just
run the modes we know are of interest.

j

>
> If TLUD gas and char are different than gas and char from updraft or
> downdraft gasifiers, or pyrolyzers operated in different conditions it would
> be useful to characterize their properties. I would expect the gas from TLUD
> to be higher in CO2, N2 and lower in condensable tars, CO and H2 than the
> others. If so is it similar to a downdraft gas that simply has a higher
> equivalence ratio (say closer to 0.4 than 0.2)? That is useful to know for
> designing combustors for the gas for various uses.
>
>
>
> I think the chars have been described as similar to the oxidative chars from
> downdraft gasifiers. Is there any consistency with regard to the extent of
> carbonization (% fixed carbon) or other physical or chemical qualities of
> TLUDD chars compared with the downdraft chars? Are there any distinctive
> qualities of TLUD chars from agronomic trials? What do soils and plants
> like/dislike about TLUD chars? Do they have more affinity to chemicals than
> other chars?
>
>
>
> Tom MIles
>
>
>
> From: Hugh McLaughlin [mailto:hmcLaughlin at alternabiocarbon.com]
> Sent: Sunday, December 11, 2011 7:52 AM
> To: Tom Miles; Discussion of biomass pyrolysis and gasification; Paul
> Anderson; William Ayres; Kathy Nafie; Jim Fournier; Mukunda HS
> Cc: Hugh McLaughlin
> Subject: RE: [Gasification] W-Gas and P-Gas defined - and redefined
>
>
>
>
>
> Hello everyone,
>
> At BEF Stove and CHAB camps, we have used the following logic:
>
> Wood burns in two steps: Wood, when heated, converts to char and char, when
> exposed to available oxygen and sufficiently hot, converts to ash.
>
> Conditions that convert the wood to char generate "wood gas" and leave
> behind the char.
>
> Conditions that convert char to ash generate "char gas" and leave behind
> ash.
>
> Conditions that do both, by converting wood to char and char to ash in the
> same regime, produce both wood gas and char gas - as in most open campfires.
>
> This set of parallels has the advantage that students seem to get is better
> than the set of definitions Tom suggested.
>
> It is clear that the gas composition will be a function of both the starting
> fuel and the conditions of transformation, which makes me uncomfortable
> trying to predict a gas composition from just the conversion process. Making
> things worse, the relatively wide range of conditions present within any
> class of conversion processes means that a wide range of gas compositions
> are anticipated - an essentially impossible to predict.
>
> I am actively trying to get out of the "impossible predictions business".
>
> - Hugh McLaughlin
>
>
>
> Hugh McLaughlin
> Director of Biocarbon Research
> Alterna Biocarbon
> ...............................................
> P: 250-649-2460
> F: 250-563-1880
> P. O. Box 2250
> Prince George, BC  V2N 2J8
> ...............................................
>
> -----Original Message-----
> From: Tom Miles [mailto:tmiles at trmiles.com]
> Sent: Sat 12/10/2011 6:26 AM
> To: 'Discussion of biomass pyrolysis and gasification'; Hugh McLaughlin;
> 'Paul Anderson'; 'William Ayres'; 'Kathy Nafie'; 'Jim Fournier'; 'Mukunda
> HS'
> Subject: RE: [Gasification] W-Gas and P-Gas defined
>
> Tom Reed,
>
> For a start, has a laboratory characterized the gas and charcoal from
> pyrolytic gasification and compared it to "wood gas" or char from pyrolysis
> or gasification? I have not seen data plots from a gas analyzer on a TLUD or
> full characterization of the gases, tars or chars.
>
> Thanks
>
> Tom Miles
>
> -----Original Message-----
> From: gasification-bounces at lists.bioenergylists.org
> [mailto:gasification-bounces at lists.bioenergylists.org] On Behalf Of Thomas
> Reed
> Sent: Saturday, December 10, 2011 5:34 AM
> To: Discussion of biomasspyrolysis and gasification; Hugh McLaughlin; Paul
> Anderson; William Ayres; Kathy Nafie; Jim Fournier; Mukunda HS
> Subject: [Gasification] W-Gas and P-Gas defined
>
> 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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>
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