Flue gas denitrification

Flue gas denitrification refers to the process of removing nitrogen oxides from the combustion flue gas to prevent excessive nitrogen oxides from polluting the environment after coal combustion in the boiler.

Common flue gas denitrification technologies are mainly the following:

Selective Catalytic Reduction (SCR):

Principle: Under the action of the catalyst, ammonia is sprayed into the flue gas at a temperature of about 280-420℃ to reduce nitrogen oxides into nitrogen and water.

Chemical reaction formula：

4NO + 4NH₃ + O₂ → 4N₂ + 6H₂O；6NO₂ + 8NH₃ → 7N₂ + 12H₂O

Advantages: High denitrification efficiency, generally up to 80% - 90%; mature technology and reliable operation.

Selective non-catalytic reduction (SNCR):

Principle: Without using a catalyst, a reducing agent such as ammonia or urea is sprayed into the furnace at a temperature of 850 - 1100 ° C to reduce nitrogen oxides to nitrogen.

Principle: Without using a catalyst, a reducing agent such as ammonia or urea is sprayed into the furnace at a temperature of 850 - 1100 ° C to reduce nitrogen oxides to nitrogen.

Chemical reaction formula：

4NH₃ + 6NO → 5N₂ + 6H₂O；CO(NH₂)₂ + 2NO → 2N₂ + CO₂ + 2H₂O

Advantages: The investment cost is relatively low and the construction period is short.

SNCR - SCR combined denitrification technology:

Principle: It combines the advantages of SNCR and SCR, with preliminary denitrification through SNCR, and unreacted nitrogen oxides further denitrified in the downstream SCR reactor.

Advantages:To a certain extent, it reduces costs and improves denitrification efficiency.