NH3 converter troubleshooting

[bigsteve80]

The CEMS for our reformer stack utilizes a NH3 converter, essentially a small vessel with stainless steel balls as packing. It's heated to 1300 degF or so, to oxidize the NH3 to NOx, and the NOx is measured before and after.
We're having a problem with the new converters taking up to 6 days to burn in to where the conversion occurs enough to pass the daily validation. Combined with that, the converter starts not working after about 3 months, so there are times where we approach our CEMS downtime.
Any idea on what could cause the delay of the converter starting to convert? And, what could cause it to die so soon (our fuel is natural gas and tail gas, no heavies)?
Thanks!

 

[georgeverghese]

There could be many reasons - are these stainless steel balls the catalyst for this oxidation reaction ? I'd hazard a guess and ask if this catalyst bed is to be flooded ( and kept under slight positive pressure) with N2 gas upon hot shutdown to prevent unintended oxidation of the catalyst ?