Re: GAS-L: Spontaneous Ignition Temperature Of Producer Gas

[W.deJong@wbmt.tudelft.nl]

On 10 Sep 2002, at 15:31, Graeme Williams wrote:
Dear Selvakumar and gasification list members,

I can agree to the range of temperatures Graeme Williams 
mentions for ignition of low calorific value (LCV) gas. We  
generated LCV gas with a bubbling pressurised fluidised bed 
gasifier including hot gas ceramic filter cleaning. Here it was also 
not really easy to ignite the gas mixture. We needed temperatures 
around 630 °C at the combustor inlet for good and stable ignition 
as well. We did experiments with excess preheated and cold air in 
the thermal power range from 500 kW to ca. 1MW. The LCV gas 
was ignited with electrical sparks at pressures of ca. 3-5 bar (abs.).

with kind regards,

Wiebren de Jong.

> Hello Selvakumar
> 
> It is unlikely that spontaneous ignition will take place by adding
> cold air to hot gas.  If it did, all that would happen is that it
> would flash back to the point where the air is being mixed with the
> gas.
> 
> The spontaneous ignition temperature of producer gas is about 570
> degrees C, but the hydrogen content does change this as you would
> expect.  The key factor is the temperature, not the air/gas ratio
> which surprised me when I first saw this demonstrated last year.
> 
>  In the presence of excess air  the ignition didn't initiate  until we
>  had
> 630 degrees C on the gauge.  The gas/air ratio only becomes critical
> when the gas is cold as you experience with engines.
> 
> Another factor  to consider in your research is that your hot gas is
> likely to contain soot or char particles.  These are always hotter
> than the gas stream and could cause ignition when they come into
> contact with air.
> 
> Hope this is of assistance to your understanding.
> 
> Regards
> Doug Williams
> Fluidyne Gasification.
> 
> 
> Gasification List Moderator:
> Tom Reed, Biomass Energy Foundation,  tombreed@attbi.com Biomass =
> Energy Foundation, www.woodgas.com List-Post:
> <mailto:gasification@crest.org> List-Help:
> <mailto:gasification-help@crest.org> List-Unsubscribe:
> <mailto:gasification-unsubscribe@crest.org> List-Subscribe:
> <mailto:gasification-subscribe@crest.org> - Gasification List Archives
> http://www.crest.org/discussion/gasification/200202/ Bioenergy 2002
> http://www.bioenergy2002.org/ 200 kWe CHP Discussion
> http://crest.org/discussiongroups/resources/gasification/200kWCHP.html
> Gasification Reference
> http://www.crest.org/articles/static/1/1011975339_7.html
> 
> >
> 
> 


Wiebren de Jong, MSc.
TU Delft
Faculty of Mechanical Engineering & Marine Technology
Section Thermal Power Engineering (EV)
Mekelweg 2
NL-2628 CD  Delft
The Netherlands
Telephone: +31 15 2789476
Mobile: +31 6 51236425
Telefax: +31 15 2782460
e-mail at home: wkdejong@kabelfoon.nl
e-mail general: wiebrendejong@hotmail.com

Gasification List Moderator:
Tom Reed, Biomass Energy Foundation,  tombreed@attbi.com Biomass =
Energy Foundation, www.woodgas.com
List-Post: <mailto:gasification@crest.org>
List-Help: <mailto:gasification-help@crest.org>
List-Unsubscribe: <mailto:gasification-unsubscribe@crest.org>
List-Subscribe: <mailto:gasification-subscribe@crest.org>
-
Gasification List Archives http://www.crest.org/discussion/gasification/200202/
Bioenergy 2002 http://www.bioenergy2002.org/
200 kWe CHP Discussion
http://crest.org/discussiongroups/resources/gasification/200kWCHP.html
Gasification Reference http://www.crest.org/articles/static/1/1011975339_7.html

>