Emissions of air pollutants from sintering flue gas in the Beijing-Tianjin-Hebei area and proposed reduction measures

Iron and steel manufacturing, especially the sintering process, is highly energy- and pollution-intensive, and is responsible for substantial emissions of major air pollutants in China, including particulate matter (PM), sulfur dioxide (SO2), and nitrogen oxides (NOx), which poses challenges to air quality improvement in the country. In this study, we carried out a comprehensive analysis of the temporal and spatial characteristic of SO2, NOx, and PM emission concentrations, quantified the standard-reaching rate and air pollutant emissions factors, as well as discussed the spatial distribution and potential reduction measures of emission amounts based on the hourly online monitoring data and basic information collected from sintering head process in the Beijing-Tianjin-Hebei region (BTH) in 2017. We found that there was a downward trend of monthly emission concentrations during September to December 2017, in response to the emission control policies. By comparing with the emission standard implemented in 2017, the standard-reaching rate of PM, NOx, and SO2 were 74.7%, 23.5%, and 62.5% respectively, higher relative to the ultra-low emission standard. The emission factors of PM, NOx, and SO2 were calculated at different sintering machine scales, and were found to be lower than previous estimates. The emissions of SO2, NOx, and PM from sintering machine heads in the BTH region amounted to 14.2 kt, 143.2 kt and 46.3 kt respectively, Tangshan and Handan accounted for over 60% of the total emission amounts. The most popular technologies applied for PM and SO2 removals are electrostatic precipitators and limestone-gypsum flue gas desulfurization with an average removal efficiency of 71.8% and 90.3%. The potential of NOx reduction is huge, more effective technical measures shall be adopted to further reduce the NOx emission amount during the sintering process.