What is the sequential process of desulfurization and denitrification for the coal-fired boiler?

As the state environmental protection requirements become more and more strict, there are also relevant regulations and standards for boiler pollutant discharge. As a result, what is the sequential process of desulfurization and denitrification for the coal-fired boiler?

The flue gas treatment of the coal-fired boiler:

Above all, the first step of flue gas treatment of coal-fired boiler is dust removal. There are fly ash and dust generated in the combustion process of coal and they can not be directly discharged to the atmosphere, so the dust reduction is necessary. Coal-fired boilers are all equipped with dust collectors and mainly adopt heat-resisting bag dust collectors.

Then, desulfurization. Flue gas produced by coal combustion contains sulfur dioxide. The main desulfurization methods are two-alkali desulfurization and limestone-gypsum method. The combination of two methods will have a better desulfurization effect. It should be noted that anti-corrosion work must be done because the acidity of flue gas produced by coal combustion is strong.

Finally, denitrification. Removing the NOx contained in the flue gas produced by coal combustion usually adopt SNCR or SCR denitrification method, which is widely applied in the denitrification work in the coal-fired power plants at home and abroad.