In the flue gas treatment process, the first denitrification or dust removal is not fixed, need to be based on flue gas characteristics, treatment processes and equipment requirements and other factors to determine.

For the use of selective catalytic reduction (SCR) denitrification process, usually priority dust removal.This is because the catalyst in the SCR process requires high flue gas cleanliness, if denitrification first, a large amount of dust in the flue gas will lead to catalyst pore clogging, reducing its activity and service life, increasing operating costs.For example, in coal-fired power plants, most of the dust is first removed by electrostatic precipitator or bag filter, so that the flue gas dust content entering the SCR reactor meets the standard, which can effectively guarantee the denitrification efficiency and catalyst performance.

If selective non-catalytic reduction (SNCR) denitrification process is used, due to the fact that the process does not require a catalyst and the reaction temperature is high, the sensitivity to dust is low, and denitrification can be carried out first.Under the high temperature environment, denitrification reaction is easier to carry out, this time the first denitrification can make full use of flue gas waste heat, improve the reaction efficiency.After denitrification and then dust removal, can avoid the by-products produced in the process of denitrification mixed with dust, affecting the effect of dust removal.

In addition, for some small industrial boilers, if the flue gas concentration of nitrogen oxides and dust are low, can also be flexible according to the actual situation to adjust the order, or even denitrification, dust removal link combined processing, simplify the process, reduce equipment investment and operating costs.In short, reasonable arrangement of denitrification and dust removal order, is to realize the efficient purification of flue gas, to ensure the stable operation of the equipment is the key.