SNCR (Selective Non-Catalytic Reduction) In the SNCR system, whose process efficiency is around 60%, ammonia (NH3) reacts with harmful nitrogen monoxide (NO), nitrogen dioxide (NO2) and forms harmless nitrogen (N2) and water vapor (H2O). The NH3 of ammonia for SNCR is between 850°C and 1,100°C'. The reagent (ammonia, aqueous ammonia or urea) is injected into the region with these levels for temperature. The reagent reacts with NOX to form harmless nitrogen and water. The design, arrangement, and location of reagent injection lances are critical to the performance of the SNCR system. Exceeding or falling below the temperature value will lead to the formation of additional NOX or an increase in NH3 release.
SCR (Selective Catalytic Reduction) systems are used when high levels of nitrogen oxides (NOX) in flue gases and high nitrogen oxide reduction rates are required. Process efficiency is >90%. The location of a DeNOX / SCR system in a flue gas cleaning process depends on the fuel type.