Re: GAS-L: NOx and Gasifiers

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

Dear Sue and All:

We need some careful analyses to sort out the following chemistry relative
to NOx and NH3.

Under the conditions of high temperature combustion NOx is likely to be
formed simply from the air, thermodynamically stable.  Lower temperatures
make less NOx.

At lower combustion temperatures no thermodynamic NOx is formed, but prompt
NOx can be formed from nitrogen contained in the fuel.

Gasification temperatures are too low to form NOx from the air, so wood
gasification does not make NOx, as Doug Williams says.

However, the reducing conditions of gasification CAN make ammonia, NH3.  I
believe NH3 dissociates easily at combustion temperatures to N2 and H2O, not
NOx.  Anyone know otherwise?

So, maybe a gasification/combustor system makes less NOx than a straight
combustor.

If anyone springs with the cash, I would love to test all this out on a
laboratory wood pellet stove I'm thinking of making, with extra controls and
emissions tests.

Onward,                     TOM REED               BEF GASWORKS/STOVEWORKS

----- Original Message -----
From: "Dr. Sue Kelly" <skelly@woodlandchemicals.com>
To: "Tom Miles" <tmiles@trmiles.com>
Cc: "gas" <gasification@crest.org>
Sent: Thursday, June 27, 2002 10:42 AM
Subject: Re: GAS-L: NOx and Gasifiers


> Dear Mr. Miles:
> Is the efficiency of the large scale sewage sludge system published?  If
so, can
> we get a copy of it easily?
> Thank you.
> Dr. Sue Kelly
>
> Tom Miles wrote:
>
> > Doug,
> >
> > One should not conclude that gasifiers do not make NOx. We measured NOx
from
> > the gasification of fuels with different nitrogen contents and found
that,
> > for a given system, NOx generation is proportional to N content.
> >
> > Comparisons of NOx reduction from gasification with staged combustion
and
> > flue gas recirculation with SNCR (selective non catalytic reduction
using
> > ammonia or urea) are welcome. To my knowledge, except for one large
scale
> > sewage sludge system, efficiencies of staged combustion and FGR
techniques
> > for high nitrogen fuels have not been published.
> >
> > Regards,
> >
> > Tom Miles
> >
> > ----- Original Message -----
> > From: "Graeme Williams" <graeme@powerlink.co.nz>
> > To: <gasification@crest.org>
> > Sent: Wednesday, June 26, 2002 1:43 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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> > >
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> >
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> > http://www.crest.org/articles/static/1/1011975672_7.html Carbon
>
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>
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>



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www.webpan.com/BEF
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http://www.crest.org/articles/static/1/1011975672_7.html Carbon