NOx Emissions from Ammonia Flares

[bw1055]

Hi, I was wondering if anyone knows of a source for an emission factor for the formation of NOx from the operation of a NH3 flare. The stream to be flared is natural gas diluted with ammonia at various concentrations (from 10-100%). In searching this forum, and elsewhere (Zeeco's website), I have read that NOx emissions from NH3 flares can vary from de minimis to 1 mol of NH3 produces 1 mol of NOx. I was wondering if anyone knew of a flare study or other data that could answer this question.

These are the two sources of data I have found so far and they contradict one another:

http://www.eng-tips.com/viewthread.cfm?qid=186352

http://www.zeeco.com/pdfs/Zero-Ammonia-Emissions-Project-3.pdf

Thank you in advance for any information provided!

 

[mbt22]

Where do you see a contradiction between your two links? You're burning NH3 to a mixture of NOx and water,. Unless you're doing some form of selective catalytic oxidation, 1 mol of NH3 produces 1 mol of NOx plus whatever little bit of NOx you get from the combustion air.

Matt

 

[bw1055]

Matt, the third poster stated: "and don't listen to the environmental types telling you about NOx. there might be some but not much."

Since I originally posted my question, I found an article by J. O. L Wendt and C.V. Sternling from November 1974. They were testing ammonia fuels burned in a bench scale meeker burner. Their study concluded that NH3 to NOx was a strong function of excess air and that at stoichiometric and sub-stoichiometric air-fuel ratios, all the NH3 pyrolized forming mostly N2 and little NOx.

I am guessing that for flares (especially those that are air and steam assisted), the tendency would be to have plenty of excess oxygen, leading to significant NOx formation.

 

[mbt22]

Sorry for the delay in replying. You're right, I made the implicit assumption that any flare is a diffusion flame, not premixed, and designed to give destruction of the material fed to it.

Matt