title: Reducing NOx Emissions for a 600 MWe Down-Fired Pulverized-Coal Utility Boiler by Applying a Novel Combustion System.
abstract: A novel combustion system was applied to a 600 MWe Foster Wheeler (FW) down-fired pulverized-coal utility boiler to solve high NOx emissions, without causing an obvious increase in the carbon content of fly ash. The unit included moving fuel-lean nozzles from the arches to the front/rear walls and rearranging staged air as well as introducing separated overfire air (SOFA). Numerical simulations were carried out under the original and novel combustion systems to evaluate the performance of combustion and NOx emissions in the furnace. The simulated results were found to be in good agreement with the in situ measurements. The novel combustion system enlarged the recirculation zones below the arches, thereby strengthening the combustion stability considerably. The coal/air downward penetration depth was markedly extended, and the pulverized-coal travel path in the lower furnace significantly increased, which contributed to the burnout degree. The introduction of SOFA resulted in a low-oxygen and strong-reducing atmosphere in the lower furnace region to reduce NOx emissions evidently. The industrial measurements showed that NOx emissions at full load decreased significantly by 50%, from 1501 mg/m3 (O2 at 6%) to 751 mg/m3 (O2 at 6%). The carbon content in the fly ash increased only slightly, from 4.13 to 4.30%.
authors.affiliation: State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology , Wuhan, Hubei 430074, People's Republic of China.
authors.forename: Lun
authors.initials: L
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology , Wuhan, Hubei 430074, People's Republic of China.
authors.forename: Qingyan
authors.initials: Q
authors.lastname: Fang
authors.affiliation: Electric Power Research Institute, Hunan Power Company , Changsha, Hunan 410000, People's Republic of China.
authors.forename: Dangzhen
authors.initials: D
authors.lastname: Lv
authors.affiliation: State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology , Wuhan, Hubei 430074, People's Republic of China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Electric Power Research Institute, Hunan Power Company , Changsha, Hunan 410000, People's Republic of China.
authors.forename: Yiping
authors.initials: Y
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology , Wuhan, Hubei 430074, People's Republic of China.
authors.forename: Gang
authors.initials: G
authors.lastname: Chen
authors.affiliation: Electric Power Research Institute, Hunan Power Company , Changsha, Hunan 410000, People's Republic of China.
authors.forename: Xuenong
authors.initials: X
authors.lastname: Duan
authors.affiliation: Jinzhushan Thermal Power Company, Datang Huayin Electric Power Company, Limited , Loudi, Hunan 417500, People's Republic of China.
authors.forename: Xihuan
authors.initials: X
authors.lastname: Wang
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D003031:Coal; D003198:Computer Simulation; D052918:Environmental Restoration and Remediation / Q000379:methods*; D009566:Nitrates / Q000032:analysis*; D009573:Nitrites / Q000032:analysis*; D009716:Numerical Analysis, Computer-Assisted; D010100:Oxygen / Q000032:analysis; D011210:Power Plants / Q000295:instrumentation*; D015203:Reproducibility of Results; D013696:Temperature
chemical_list: D000393:Air Pollutants; D003031:Coal; D009566:Nitrates; D009573:Nitrites; D010100:Oxygen