Other predominant component will be nitrogen since it is thermodynamicly favored comparing with NOx. Concerning exhaust gas treatment it doesn't matter where NOx originates from (fuel or thermal). If you have lean conditions (more oxygen than needed) your NOx emmissions should raise in general and you can use either H2 deNOx or SCR technique to remove NOx emmissions.

The effectiveness of NOx control by non-catalytic NOx reduction, which is the technique you are proposing, depends strongly on temperature. In the correct window, NH3 should be effective. There is ample H2O already in the gas, but NH3 commonly comes dissolved in H2O. H2 addition, depending on the amount, will potentially raise the local temperature and could make NOx problem worse. Additional H2O addition could lower the local temperature and make the NH3 not react, which would cause serious materials and emissions problems itself. 

An important way to drammatically reduce NOx emissions is to take away N2 from the mixture that enters the combustion chamber or turbine. This is called Oxy-fuel combustion (see https://en.wikipedia.org/wiki/Oxy-fuel_combustion_process).

There are specialized companies that provide excellent oxy-fuel solutions (see for example http://www.iteaspa.it/en/ ).

NH3 and urea are the usual reactants. Both come dissolved in water (that is already available abundantly - except for pure carbon.

Lowering the combustion temperature would reduce NOx - at the same time reducing efficiency. For oxy-fuel, I'm not sure about the overall efficiency: getting the pure oxygen required is not exactly for free, instead quite energy-intensive.

As already stated: getting your process window right is more important than the chaice of reactant.

Regards

Dear Dreher,

At first glance, adequate Time Window seems a key issue to look at regarding the apparently opposed responses (regarding adding H2 to the combustion),

Do you have recent literature on this?

Dear Julio,

sorry - no literature at all. This was just a "side-issue" in a project a long time ago. In automootive applications, urea (aka "adblue") is the standard solution: simple and safe.

But I doubt that adding H2 will significantly improve the process (if at all), while greatly increasing the technical efforts and risks. Ammonia or urea will easily do. And if you need more H2 in the process it is simple to increase the NH3 resp. urea fraction.

Regarding "Time window": within the thermal limits there may be a minimum time for the passage. Can't see a reason for a maximum time limit: once the reduction is done, these are no agents to react under the current conditions.

Regards

 Thank you all for your answers (I could not manage answering to each of you).

Now, should I remove the H2 gas, I fear at least two problems (I might be wrong):

1.- face difficulties to burn the ammonia along,

2.- reduced efficiency; and not been able to use H2 as an active control component for the burning process.

Where can I find interesting works for successfully burning ammonia while maintaing low NOx emission? gas turbine emissions standars burning natural gas is as low as 25 ppm, quite stringent.

Oh, until now I was slightly irritated by the "ammonia gas turbine"...

You really want to burn ammonia? Which is very valuable in producing fertilizers etc.? If so, one approach would be to use pure oxygen (resulting in low or no NOx). Or - and only now I understand your initial question - to burn the NH3 in a flame sustained by some other reactant - which could be H2. 

Honestly: if you do not have ammonia in abundance, I would not consider to oxidize it. There are other ways to 'get rid of it' while at the same time creating useful products.

Regards

Thanks for your replay.

Currently Mexico is number 10 in the rank list of polluting countries, but we have a high increase rate in pollution. PEMEX produces ammonia. But ammonia can be produced from organic urea and by solar energy; I bet on these later two green processes.

I did not quite understood your suggestion. Do you mean burning just the ammonia plus oxigen? I also recently read that platinum coating (or another type of coating) for the combustor components could be useful; is this so?

I'm slightly irritated: the title "... ammonia gas turbines ..." at least allows the interpretation that you would want to burn ammonia to power the turbine. Now you leave me a bit confused whether you want the ammonia 'only' for de-NOx-ing or as the fuel itself...

Anyway: if you do a bit of researching into automobile 3-way catalytic converters, you will find that Pt promotes the formation of NOx. Which is quite the contrary to what you try to achieve. I think contributions about the automotive application might be a reasonable source of information due to their widespread use, broad data base etc.

Regards

Julio C Gomez-Mancilla I hope you have been able to find appropriate answers to your questions. Recent studies from my group propose methods of controlling fuel NOx emissions from ammonia gas turbines through rich-lean combustion concept (e.g Article Towards the development of an efficient low-NOx ammonia comb...

Article Influence of steam addition and elevated ambient conditions ...

Thank you very much Mr. Okafor for your answer.

Unfortunately, I abandoned this research due to insufficient funding interest in Mexico.

Currently I continue investigating reduction of NOx contaminants; but those occurring in ICE engines, driven by gasoline plus HHO; where a natural idea is to add H2O into the air stream.

Yet; do you, or someone else, have information about it? I`ll appreciate it much to send your replay to my personnal email:

[email protected]