SNCR
Overview
Hitachi Zosen Inova offers two non-catalytic processes to reduce nitrogen oxides:
- The SNCR process (ammonia-water injection, 2ndpass boiler) and the DyNOR™ technology as a further developed solution of the SNCR process
The Hitachi Zosen Inova SNCR Process
In the SNCR process (Selective Non-Catalytic Reduction), NOx reacts with ammonia (NH3) and is chemically converted into nitrogen (a natural constituent of air) and water vapour. Ammonia is injected directly into the combustion chamber along with steam at a temperature between 850°C (1560°F) and 1000°C (1830°F). Achieving high removal efficiency of NOx requires injecting more ammonia than is consumed. The excess can be removed downstream by the wet scrubbing process. With our patented process, the ammonia is recovered from the effluent and can be reinjected into the post combustion chamber.
Another advantage of this process: dioxin formation in the flue gas is reduced significantly.
This process has been used successfully for many years in numerous waste processing plants. Experience demonstrates that the SNCR DeNOx process is capable of removing up to 90% of the nitrogen oxide from the flue gas.
The equipment (ammonia water tank, pump rack, ammonia water and steam distribution pipes) takes very little space and can be added very easily to existing plants.
Application
To reduce NOx to 120 – 150 mg/Nm3, simple ammonia water injection equipment is needed.
If NOx is reduced to less than 120 mg/Nm3, the excess of ammonia has to be removed in a downstream by the wet scrubbing process.
The HZ Inova SNCR system can be installed at every type of EfW boiler, and depending on the system, removal from 50% to 90% is possible.
