基于燃煤电厂“近零排放”的大气污染物排放限值探讨

针对神华集团典型“近零排放”燃煤机组，考察了大气污染物（烟尘、SO₂、NO_x、汞及其化合物）的排放特征，提出了更加契合绿色发展生态环保要求的燃煤电厂大气污染物排放限值，即烟尘、SO₂、NO_x和汞及其化合物排放限值分别为1、10、20和0.003 mg/m3（简称“‘1123’排放限值”）.评估了新建“近零排放”燃煤机组的长期运行排放状态，并研究了“近零排放”机组汞污染协同减排效果.结果表明，2017年1—10月新建机组烟尘、SO₂、NO_x排放质量浓度平均值分别在0.69~0.77、6.04~6.63、16.56~16.79 mg/m3之间，排放绩效可低至0.0023、0.022、0.057 g/（kW·h），污染减排已达到国际领先水平；“1123”排放限值下烟尘、SO₂和NO_x的达标率分别超过92.06%、85.43%和77.46%，“近零排放”原则性技术路线可实现更好、更优的生态环保排放指标.燃煤机组通过“近零排放”技术改造，可提高烟气中Hg0的氧化效率和汞化合物的捕获效率，环保设施组合协同脱汞效率提升至75.3%~90.9%（平均值为82.8%±8.1%），汞排放水平降至0.51~1.45 μg/m3〔平均质量浓度为（0.94±0.47）μg/m3〕，基本达到国际先进煤电机组的协同控制水平.研究显示，清洁煤电大气污染物新排放限值总体上比GB 13223—2011《火电厂大气污染物排放标准》中燃煤电厂大气污染物排放限值小1个数量级，可为加快推进生态文明建设、制订先进的燃煤电厂大气污染物排放新标准提供科学依据. 

Discussion of Emission Limits of Air Pollutants for 'Near-Zero Emission' Coal-Fired Power Plants

The emission characteristics of air pollutants (i.e., particulate matter (PM), SO₂, NO_x and Hg) from typical 'near-zero emission' coal-fired power plants of Shenhua Group were investigated. The '1123' emission limits of air pollutants for clean coal-fired power plant agreeing with eco-friendly requirement for green development was put forward, which required the emission limits of PM, SO₂, NO_x and Hg were 1, 10, 20 and 0.003 mg/m3, respectively. Based on the monitoring results, the long-term operation states of two new coal-fired units were evaluated. Also, the co-removal efficiency for mercury pollution in near-zero emission units has been studied. The results show that the PM, SO₂ and NO_x average emission concentrations of new units advanced in environmental indicators from January to October 2017 were in the range of 0.69-0.77, 6.04-6.63 and 16.56-16.79 mg/m3, respectively. The emission performances of PM, SO₂ and NO_x could be as low as 0.0023, 0.022 and 0.057 g/(kW·h), which is the lowest in the world. Furthermore, the discharge rates of PM, SO₂, and NO_x under the '1123' emission limits exceeded 92.06%, 85.43% and 77.46%, indicating that the principle technology roadmap of near-zero emission could achieve better and more excellent eco-friendly emission targets. After the 'near-zero emission' retrofitted, Hg synergistic removal efficiency of air pollution control devices increased to 82.8%±8.1% from 75.3% to 90.9% due to the increasing efficiencies of Hg0 oxidation and Hg compounds capture, and Hg emission concentrations were reduced to the range of 0.51-1.45 μg/m3, which basically reached the collaborative control level of world advanced coal-fired units. On the whole, the new emission limits of air pollutants for clean coal-fired power were about 1 order of magnitude less than the limits regulated in the latest Emission Standard of Air Pollutants for Thermal Power Plants (GB 13223-2011), which accelerate the ecological civilization construction and provide scientific evidence for setting new emission standard of air pollutants for coal-fired power plants.