Re: "Pyrolysis gas" energy content and composition

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

On Fri, 18 Oct 2002 23:44:56 -0600, "Tom Reed" <tombreed@attbi.com>
wrote:
>
>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.

Hi Tom, where have you been? I was waiting for you to reply on
terminology first but felt I couldn't't leave a stove's pilgrim
without a guiding light for too long ;-).

I did not imply that "woodgas" from a gasifier would not include
producer gas, indeed that is the only product from a Kalle type
gasifier running on charcoal. So a gasifier running on wood becomes a
bit of everything, a producer gas generator, a water gas generator and
a pyrolysis offgas generator as well a often producing char with the
ash. The goal of the down draught gasifier, producing a clean fuel
gas, is to minimise pyrolysis offgas products and char, by cracking
them to CO and H2 with the inevitable N2 if air blown.

Because the offgas from the idd is burned without cooling between the
pyrolysis front and the secondary burner its tars are not a problem,
as you say the small amount of primary air results in little dilution
by nitrogen and hence this tarry, hot offgas has high enthalpy.
>
>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

This is the term I have seen used, I went a step further to "pyrolysis
offgas"

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