2 replies to this topic

[Redbull010203]

Hi everyone! 
In the plant where I just moved as energy and utilities engineer, they asked me to try to assist with the boilers we use to produce steam. We have really low NOx limits, and we make us of a SCR unit. The catalyst has never been changed since 2016, and they would like to know if I can take a track of the activity of the catalyst, maybe in terms of ammonia slip. 
I am a bit struggling with that, since we inject ammonia based on the NOx concentration in the gas inlet of the SCR unit, which of course depends on the type and amount of gas we are burning in the specific moment. We have measurement of how much ammonia we inject, NOx concentration in, NOx concentration out. So the idea would be to calculate the NH3 out of the stack and track it somehow over time in a comparable way ( similar gas burnt over time, similar steam production, etc..). 
To do that, someone before me tried to do stoichiometrically, but not knowing exactly how much NO and how much NO2 is included in the NOx( we guess 95% NO) and also we do not know which of the several reactions possible occur in any moment, the results were not useful. 
I tried to use a formula I found online, attached here. 

But I came up with an ammonia slip of around 500 ppm when it should be lower than 5 ppm, so I might have done units mistakes or some mistake in assumptions..

Anyone with experience on something similar or who has any suggestion?

Thanks in advance! 

 

[Pilesar]

I suggest contacting the catalyst manufacturer asking how you can best verify performance. Maybe someone there would be interested since it means a possible sale for them.

[breizh]

Hi,

Consider these documents to support your work.

It may help to confirm your data. 

BTW no correlation shared with us.

Breizh