Flue gas denitrification

Flue gas denitrification refers to the process of removing nitrogen oxides from combustion flue gas in order 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 to 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 temperature area of ​​850-1100℃ to reduce nitrogen oxides to nitrogen.

● Chemical reaction formula: 4NH₃ + 6NO → 5N₂ + 6H₂O; CO(NH₂)₂ + 2NO → 2N₂ + CO₂ + 2H₂O

● Advantages: relatively low investment cost and short construction period.

SNCR - SCR combined denitrification technology:

● Principle: combining the advantages of SNCR and SCR, first denitrification through SNCR, and unreacted nitrogen oxides are further denitrified in the downstream SCR reactor.

● Advantages: reduces costs to a certain extent and improves denitrification efficiency.