The process of desulfurization is to make slurry of alkaline desulfurizer and mix it with boiler flue gas, SO2 becomes acid when it meets water and reacts with alkaline desulfurizer to produce CaSO₄, etc. Denitrification The principle of denitrification is similar to that of desulfurization, except that the denitrifying agent is replaced by ammonia or urea.

I. SCR technology(Selective catalytic reduction technology): mainly using NH₃, urea, etc. as reducing agents, selectively reducing NO2 to non-toxic and harmless products N2 and H2O over an appropriate catalyst.

N2+O——>NO+N

N2+O2——>NO+O

N+OH——>NO+H

II. Ozone oxidation technology: the integrated technology of desulfurization and denitrification, which utilizes the strong oxidizing property of O3 to oxidize the insoluble NOx in flue gas into NO2, NO3 and N2O5 which are easily soluble in water, and is absorbed by the subsequent system together with SO2 in the spray tower by alkali solution.

NO₂+H₂O——>HNO₃+NO

N₂O₅+H₂O——>HNO₃

NO+NO₂+2NaOH——>2NaNO₂+H₂O

III. Plasma technology: plasma treatment of SO2 and NOx in flue gas is a dry desulfurization and denitrification technology that uses activated oxidation that generates high-energy electrons to generate ammonium sulfate and ammonium nitrate from the oxides of SO2 and NOx in flue gas with the addition of NH3.