Controlling the Oxides of Nitrogen

The oxides of nitrogen consist of the elements nitrogen and oxygen. Nitrogen can form several different oxides. The stable gaseous oxides of nitrogen include N 2 O (nitrous oxide), NO (nitric oxide), N 2 O 2 (dinitrogen dioxide), N 2 O 3 (nitrogen trioxide), NO 2 (nitrogen dioxide), and N 2 O 5 (nitrogen pentoxide). There are three principal chemical processes for NO x formation: thermal NO x , prompt NO x , and fuel NO x . The chapter describes factors that affect the formation of NO x in combustion processes. There are essentially six principles of NO x control: reducing peak flame temperature, reducing residence time at peak temperature, chemical reduction of NO x , removal of nitrogen, use of a sorbent, and combination of multiple methods. The chapter describes some information on NO x pollution prevention methods. In addition to the pre-combustion or in-combustion techniques, NO x can also be reduced in post-combustion processes. This allows burners to operate in a more efficient, high-intensity manner while still maintaining low NO x emissions.