Nitrogen oxides that cause pollution of the
environment are converted to nitrogen and water by adding a reducing agent (urea solution
With the SCR process the reducing agent is injected at comparatively low temperatures
and the nitrogen oxides are reduced to molecular nitrogen using a catalyst.
With the SNCR process the reducing agent is injected directly into the hot flue gas at
temperatures of about 950 °C. The reducing agent reacts with the nitrogen oxides to water and
nitrogen. The advantage of this method is the low capital investment. Retrofit is possible