GAS-L: NOx and True Flame temperatures

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

Dear Graeme and all:

Glad to have confirmation of my NOx suspicions from Graeme.

~~~~~~~~~~
However, I would warn all about flame temperatures measured with
thermocouples.  The thermocouples radiate the heat transferred by the flame
VERY efficiently, and so can come to a temperature as low as half the true
flame temperature.  This can be fixed using a suction thermocouple which
increases the velocity and heat transfer over the thermocouple (and the cost
and complexity of the measurement).

The adiabatic flame temperature of most fuels is about 2000 C +/- 200 C.
(See North American Handbook, Vol 1).  Acetylene in air is 2632, CO is 2468,
H2 is 2210, methane is 1920, methanol is 1910  and PRODUER GAS is 1654  C
(because it is so dilute).

If you hold a platinum wire (or nichrome) in a methane Bunsen burner flame,
it will reach a yellow to white heat, 1000 to 1100 C, even though the true
flame temperature is 1920.

So beware most quoted "flame temperatures".

Yours truly,            TOM REED                BEF GASWORKS
----- Original Message -----
From: "Graeme Williams" <graeme@powerlink.co.nz>
To: <gasification@crest.org>
Sent: Wednesday, June 26, 2002 2:43 AM
Subject: GAS-L: NOx and Gasifiers


> Dear Colleagues,
>
> During the years that we have been playing with producer gas, both in
> engines for power generation and for process heat in timber kilns, at no
> time has NOx been an emission problem.
>
> Although gasifier temperatures are high, it appears that it just doesn't
> happen in this process although I suppose anything is possible given
certain
> conditions existing.
>
> The adiabatic flame temperature of clean producer gas ie tar free has
never
> exceeded 1100 degrees Celcius, in our experience, and in fact is one of
the
> measures we use to check to see if tar is present in the gas stream.
>
> Hope this helps.
>
> Doug Williams
> FLUIDYNE GASIFICATION
>
>
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http://www.crest.org/articles/static/1/1011975672_7.html Carbon