In the selective non-catalytic reduction (SNCR) process, nitrous oxides (NOx) react with ammonia and are chemically converted into nitrogen (a natural constituent of air) and water vapour.

For efficient denitrification (DeNOx), it is crucial to operate in the right temperature ranges. If the temperature is too high, the ammonia is “burnt”. If the temperature is too low, the reaction slows, and a large portion of the ammonia reaches the stack unused. The ideal temperature range is to be found in the post-combustion chamber, although there it is subject to fluctuation because of variations in load and fuel. To prevent this, the reducing agent (ammonia water or urea) is injected into the post-combustion chamber at various points.

But even within the optimum temperature range, the NOx separation rate with a conventional SNCR process is limited. Achieving higher NOx removal efficiency requires injecting more ammonia than is consumed. The excess can be removed downstream in a wet scrubbing process. In our patented process, the ammonia is recovered from the effluent and can be reinjected into the post-combustion chamber.

The main advantages of the Kanadevia Inova SNCR process:

• Low process investment and minimal infrastructure costs, thanks to simple process technology and integration of the process in the post-combustion chamber of the boiler

• Simple, precise control of the various stages via the distribution modules

• In combination with a wet scrubbing process and ammonia stripper, very low NOx limits can be achieved, and the excess ammonia can be recovered

• The system can be upgraded to create a DyNOR™ process meeting even lower NOx limits