Desulfurization and denitrification is one of the important technical measures to prevent and control air pollution, one. There are generally three desulfurization methods before combustion, during combustion, and after combustion. It also has important practical significance for the treatment of exhaust gas from various boilers and incinerators. Denitrification: In order to prevent excessive NOx from polluting the environment after the combustion of coal in the boiler, the coal should be denitrified. It is divided into denitration before combustion, denitration during combustion, and denitration after combustion.