[Digestion] Digestion Digest, Vol 9, Issue 1 NOx reduction

[Tom Miles]

I'm not familiar with recent publications on emissions from burning or
fueling engines with digester gas. As you suggest it would also depend on
the gas cleanup which is probably fairly standard by now. There is probably
engine data on digesters since they would have to be permitted. 

Several states in the US are in the process of adopting new emissions
standards for small stationary generators. Engines from digesters will have
to comply with standards that are based on natural gas engines. I do not
know if these standards have been implemented (promulgated is the agency
term).

Thanks

Tom Miles   

-----Original Message-----
From: digestion-bounces at listserv.repp.org
[mailto:digestion-bounces at listserv.repp.org] On Behalf Of stan simon
Sent: Thursday, March 08, 2007 6:01 PM
To: digestion at listserv.repp.org
Subject: Re: [Digestion] Digestion Digest, Vol 9, Issue 1 NOx reduction

I am not sure if you are talking about the digester itself or more likely 
the emissions  from the generators that are often used to burn the methane. 
There should not be any gaseous emissions from the digester itself.

One source of NOx in the generator exhaust is created from the incoming  N2 
gas in the intake air that is oxidized  in the engine.  (Air is mixed with 
methane in the carburetor)  Treatment of the exhaust to remove NOx is 
difficult.  It is easier to pretreat the incoming combustion air, obtaining 
oxygen free of N2 and mix the O2 with a portion of the exhaust to substitute

for incoming air.  This produces an exhaust without NOx.

Another  source of NOx could be the ammonia  in the digester gas.  There are

membrane based separation systems available which separate the methane from 
the other gases.  It is necessary to compress the gas to 60 psia or 
thereabouts to make this work.  The remaining H2S can be removed by passing 
through a bed of iron filings.  CO2 can be removed by percolation thru water

although this may not be needful.  The NH3 is typically injected into the 
farm fields as a fertilizer.



Sincerely,
Stan L. Simon


----- Original Message ----- 
From: <digestion-request at listserv.repp.org>
To: <digestion at listserv.repp.org>
Sent: Thursday, March 08, 2007 12:00 PM
Subject: Digestion Digest, Vol 9, Issue 1


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> Today's Topics:
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>   1. Ethanol by products (LEMAIRE, Olivier)
>   2. Nitrogen Emissions from Biogas (Tom Miles)
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> ----------------------------------------------------------------------
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> Message: 1
> Date: Thu, 8 Mar 2007 11:34:16 +0100
> From: "LEMAIRE, Olivier" <Olivier.LEMAIRE at veolia.com>
> Subject: [Digestion] Ethanol by products
> To: "Digestion Discussion List" <DIGESTION at LISTSERV.REPP.ORG>
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> <B604D2F9D3EE044C96D4195C799BD1BAB03712 at sar-mail1.messagerie.ve>
> Content-Type: text/plain; charset="US-ASCII"
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>
> Hello everybody
>
> Has anybody information about the feedstocks of ethanol production
> by-products (residues) for some countries and/or worldwide ?
>
> Thank you
> Best regards
>
> O. LEMAIRE
>
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> ------------------------------
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> Message: 2
> Date: Thu, 8 Mar 2007 08:58:42 -0800
> From: "Tom Miles" <tmiles at trmiles.com>
> Subject: [Digestion] Nitrogen Emissions from Biogas
> To: "'The Digestion Discussion List'" <DIGESTION at LISTSERV.REPP.ORG>
> Message-ID: <00aa01c761a3$0781f770$0200a8c0 at Hp1270>
> Content-Type: text/plain; charset="us-ascii"
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> We have had an inquiry from a concerned farmer in Washington state (US)
> about the promotion of biogas digesters for dairy use.  His impression is
> that "Such a  dairy waste water and solids treatment system is a prolific
> emitter of N20."
>
> His question:"Does anyone have any citations for N20 emissions from a 2000
> cow dairy manure digester? How does such a digester compare to say a 100 
> mw
> coal plant?"
>
> How can nitrogen emissions from digestors be captures for use in
> agriculture?
>
> Where can we find answers to these questions?
>
> Thanks
>
> Tom Miles
>
>
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> End of Digestion Digest, Vol 9, Issue 1
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