Ducon's SNCR DeNOx Systems work by injecting ammonia or urea into the radiant and convection regions of a boiler to treat the flue gases, so the reduction reaction can take place. The reagent comes in contact with the NOx in the flue gas within a specific temperature range. For urea, this range is approximately 1600°F to 2100°F. For ammonia, the range is lower at 1500°F to 1800°F.