"Pyrolysis gas" energy content and composition

["Tom Reed" <tombreed@attbi.com>]

Dear Paul, Andrew and All:

I agree "vegie-gas" is cute, but it is nice for all of us to be on the same
page and not invent new words if old words exist and are widely used and
understood.

I wouldn't agree that the "inverted downdraft" type of gasifier doesn't
produce producer gas, since "producer gas" can cover a multitude of sins,
but mostly indicates a 5-7 MJ/m3 gas with ~ 50% nitrogen.

If you would like to be more accurate, I would propose the terms

"Pyrolysis gas" - made from the volatiles of the biomass, but leaving the
charcoal as a by-product

It is difficult to characterize the energy content of the gas because if you
cool it you will find a high proportion of "tars".  The hot gas has all the
energy value of the tars, typically much greater than the CH4, H2 and CO.
The tars are the condensible component and quite high with low volume.  The
gas has a relatively low nitrogen content, since it only takes 0.5 to 1kg of
air to pyrolyse 1 kg of biomass, while it takes 1.5 kg of air to completely
gasify dry biomass.  I would like to measure this more accurately someday
and hope we might do it at CPC.

I would appreciate comments from Jim Diebold, a long time pyrolyser at NREL,
now at CPC.

Yours truly,

TOM REED              BEF




> Andrew,
>
> Thanks for your informative reply.  (I did not see it before my previous
> message.)  YOU and a few others can get the highest scores.  People like
me
> need the tutoring!!!
>
> I will leave "zoomass" to others, but wonder if sewerage (and dung and
> feces) is "zoo- or phyto-"   (Not a topic for this list serve.)
>
> Thanks for the clarification about producer gas and water gas.  Clearly
the
> "very small gasifiers" such as mine do NOT yield producer gas.
>
> Is it acceptable to use the term "wood-gas" if the phyto-mass is actually
> corn cobs or other clearly NON-wood material?   Is the gasification of
> straw (being discussed currently) producing "wood-gas"?   If we start
> speaking of phyto-gas (or "fito-gas" in many of the Romance languages), we
> should be clear that we include "wood-gas" and other
> "dry-vegetative-matter-gas".
>
> :-))  No interest in the term "vegie-gas"?    I thought it was cute.
>
> Thanks again.
>
> Paul
>
> At 12:10 AM 10/18/02 +0100, AJH wrote:
> >On Tue, 15 Oct 2002 16:22:22 -0500, "Paul S. Anderson" <psand
> > >
> > >1.  Can regular biomass (I am not referring to the charcoal that is a
stage
> > >of biomass consumption) be consumed in fire ***without first undergoing
the
> > >release of the gases (pyrolysis and gasification)*** that are
subsequently
> > >combusted when mixed with oxygen and sufficient ignition?
> >
> >Possibly if burned as a fine powder the combustion would be so short
> >that there would be no way of separating the reactions.
> >
> > >  In other words,
> > >even in a regular "fire" of biomass, is it not true that the gases are
> > >created first, even if the gases are almost immediately "burned"?
Hence,
> > >there is no "fire" without gasification first.
> >
> >OK in general
> >
> > >
> > >If yes to the above, then all stoves COULD be considered to be
gasifiers,
> > >and we therefore need to clarify that what we have been calling
"gasifier
> > >stoves" are ones in which ***the creation of the gases takes place in a
> > >location at least slightly and control-ably removed in space and in
time
> > >from the point of the combustion of those gases***.
> >
> >I think this is the distinction that has been made in the past.
> > >
> > >2.  What are the real differences between "producer gas" and "wood-gas"
and
> >
> >Producer gas is generally taken to be CO and Nitrogen formed by the
> >gasification of carbon by air, water gas is H2 and CO formed by the
> >gasification of carbon by steam. Woodgas is a mixture of these
> >reactions and chemicals plus the pyrolysis (offgas) products of
> >thermal decomposition, it contains many compounds ranging from weak
> >organic acids, alcohols etc through to tars as vapours. Gasifiers
> >making gas for other than thermal uses attempt to "crack" these
> >pyrolysis compounds thermally to reduce them to simple gaseous
> >compounds.
> >
> > >pyrolysis / gasification of any DRY plant-origin biomass.
> >
> >This is phytomass whether wet or dry.
> >
> > >  (We do not do
> > >much gasification of dry animal-origin biomass.)
> >
> >This is zoomass and yes we do, there is much discussion on GAS-L of
> >sewage sludge gasification. I suspect one of the most successful
> >gasifiers operating is in a chrome leather works where the off cuts
> >are recycled as heat and the chromium is recovered commercially from
> >the ash.
> >
> > >
> > >Paul S. Anderson, Ph.D.,  Fulbright Prof. to Mozambique
> >
> >How many marks out of ten do I score teach :-)?
> >
> >AJH
> >
> >-
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> > >
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> >
> >Other Biomass Stoves Events and Information:
> >http://www.crest.org/articles/static/1/1010424940_7.html Bioenergy
> >http://www.crest.org/articles/static/1/1011975339_7.html Gasification
> >http://www.crest.org/articles/static/1/1011975672_7.html Carbon
> >
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>
> Paul S. Anderson, Ph.D.,  Fulbright Prof. to Mozambique 8/99 - 7/00
> Rotary University Teacher Grantee to Mozambique >10 mo of 2001-2003
> Dept of Geography - Geology (Box 4400), Illinois State University
> Normal, IL  61790-4400   Voice:  309-438-7360;  FAX:  309-438-5310
> E-mail: psanders@ilstu.edu - Internet items: www.ilstu.edu/~psanders
>
>
> -
> Stoves List Archives and Website:
> http://www.crest.org/discussion/stoves/200209/
> http://crest.org/discussiongroups/resources/stoves/
> >
> Stoves List Moderators:
> Ron Larson, ronallarson@qwest.net
> Elsen L. Karstad, elk@wananchi.com www.chardust.com
>
> Other Biomass Stoves Events and Information:
> http://www.crest.org/articles/static/1/1010424940_7.html Bioenergy
> http://www.crest.org/articles/static/1/1011975339_7.html Gasification
> http://www.crest.org/articles/static/1/1011975672_7.html Carbon
>
> List-Post: <mailto:stoves@crest.org>
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> >
> For information about CHAMBERS STOVES
>
>http://www.repp.org/discussiongroups/resources/stoves/Chambers/Chambers.htm
>
>



-
Stoves List Archives and Website:
http://www.crest.org/discussion/stoves/200209/
http://crest.org/discussiongroups/resources/stoves/
>
Stoves List Moderators:
Ron Larson, ronallarson@qwest.net
Elsen L. Karstad, elk@wananchi.com www.chardust.com

Other Biomass Stoves Events and Information:
http://www.crest.org/articles/static/1/1010424940_7.html Bioenergy
http://www.crest.org/articles/static/1/1011975339_7.html Gasification
http://www.crest.org/articles/static/1/1011975672_7.html Carbon

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>
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