Effect of Ammonia Cofiring on Coal Air-Staged Combustion Characteristics and NO Emission
Aoyang Zhang, Xiaowei Liu, Yuxiang Wang, Le Lei, Yue Zou, Yishu Xu, Minghou Xu
Abstract
Ammonia–coal cofiring is an effective method to reduce the carbon dioxide emissions from coal-fired power plants. This study conducted an experiment involving ammonia cofiring at ratios from 0 to 100 cal.% in a 50 KW self-sustaining combustion furnace. The results demonstrate that with air-staged combustion, the NO emission reduction was the greatest for pure ammonia combustion (88.0%), followed by 30% ammonia cofiring (71.6%) and pure coal combustion (67.0%). Additionally, ammonia cofiring does not universally promote coal combustion, which is related to the cofiring ratio. The assessment of the intermediate combustion process showed that cofiring ammonia at a low ratio promoted coal combustion. When the NH 3 ratio is increased, it competes with coal for O 2 in the early stage of combustion, suppressing coal combustion and increasing the unburned carbon in fly ash as well as CO emissions. Furthermore, while forming a local anoxic environment during air-staged combustion reduces NO production, it simultaneously increases CO. Therefore, it is necessary to comprehensively consider the trade-off between NO emission reduction and the complete combustion of pulverized coal.