Re: Theory and terminology questions about combustion

[AJH <andrew.heggie@dtn.ntl.com>]

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

-
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>
List-Help: <mailto:stoves-help@crest.org>
List-Unsubscribe: <mailto:stoves-unsubscribe@crest.org>
List-Subscribe: <mailto:stoves-subscribe@crest.org>
>
For information about CHAMBERS STOVES
>http://www.repp.org/discussiongroups/resources/stoves/Chambers/Chambers.htm