Emission Characteristics of Gas-Fired Boilers in Beijing City, China: Category- Specific Emission Factor, Emission Inventory, and Spatial Characteristics

10.4209/aaqr.2016.11.0506

Xiao Yan；Guangwu Song；Jing Yan；Zhiyun Luo；Xuesong Sun；Chunwang Wei；Rui Zhang；Guohao Li；Qi Ding；Di Zhang

Classification of boilers ； Uncertainty analysis ； GIS-based approach ； Operating load ； Monte Carlo simulation

Aerosol and Air Quality Research

17卷7期（2017 / 07 / 01）

1825 - 1836

英文

Gas-fired boilers are the main stationary sources of NO_x in Beijing. However, the understanding of gas-fired boilers is limited. In the present study, the emission characteristics of NO_x, SO_2, and CO from gas-fired boilers in Beijing were established using category-specific emission factors (EFs) from field measurements. To obtain category-specific EFs, boilers were classified through influence analysis. Factors such as combustion mode, boiler type, and installed capacity were considered critical for establishing EFs because they play significant roles in pollutant formation. The EFs for NO_x, CO, and SO_2 ranged from 1.42-6.86 g m^(-3), 0.05-0.67 g m^(-3) and 0.03-0.48 g m^(-3). The emissions of NO_x, SO_2, and CO for gas-fired boilers in Beijing were 11121 t, 468 t, and 222 t in 2014, respectively. The emissions were spatially allocated into grid cells with a resolution of 1 km × 1 km, and the results indicated that top emitters were in central Beijing. The uncertainties were quantified using a Monte Carlo simulation. The results indicated high uncertainties in CO (-157% to 154%) and SO_2 (-127% to 182%) emissions, and relatively low uncertainties (-34% to 34%) in NO_x emission. Furthermore, approximately 61.2% and 96.8% of the monitored chamber combustion boilers (CCBs) met the standard limits for NO_x and SO_2, respectively. Concerning NO_x, low-NO_x burners and NO_x emission control measures are urgently needed for implementing of stricter standards. Adopting terminal control measures is unnecessary for SO_2, although its concentration occasionally exceeds standard limits, because reduction of its concentration can be achieved thorough control of the sulfur content of natural gas at a stable low level. Furthermore, the atmospheric combustion boilers (ACBs) should be substituted with CCBs, because ACBs have a higher emission despite lower gross installed capacity. The results of this study will enable in understanding and controlling emissions from gas-fired boilers in Beijing.