In order to meet the ultra-low emission standards

a supercritical 660 MW unit with circulating fluidized bed boiler installs a set of selective non-catalytic reduction(SNCR) denitration device in the cyclone separator. The effects of temperature

ammonia nitrogen molar ratio

oxygen content and circulating ash components on the SNCR flue gas denitration were experimentally investigated. The results show that

as the temperature increased from 800 ℃ to 950 ℃

the denitrification efficiency increased continuously and reached the peak value at 950 ℃. At higher temperatures

the denitration efficiency dropped due to the NH_3. At temperatures lower than 850 ℃

temperature became the controlling factor of the reaction and rising the mole ratio of ammonia to nitrogen had little influence on the denitration efficiency enhancement. While at temperatures higher than 850 ℃

rising the mole ratio of ammonia to nitrogen would significantly improve the denitrification efficiency

but when the mole ratio of ammonia to nitrogen is larger than 1.50

the denitrification efficiency rise slowed down. When the oxygen content was 0

the number of OH and other active roots was very small

which resulted in a decline in the SNCR reaction

and the increasing oxygen content improved the NH_3 oxidation and decreased the denitrification efficiency. The circulating ash containing Fe_2O_3 and CaO could enhance the NH_3 oxidation thus to reduce the denitrification efficiency.