超低排放典型燃烧源颗粒物及水溶性离子排放水平与特征

研究以自行开发建立的超低排放高湿废气中总颗粒物（total particulate matter，TPM）的直接冷凝采样系统及监测方法，应用于3台北京市超低排放典型燃烧源烟气中颗粒物的排放监测.分析和评估超低排放典型燃烧源排气中颗粒物及其水溶性离子的排放水平与组成特征，探究可过滤颗粒物（filterable particulate matter，FPM）和可凝聚颗粒物（condensable particulate matter，CPM）及其水溶性离子的相互作用与影响因素.结果表明：北京市超低排放燃煤锅炉FPM基准氧含量排放浓度介于1.04~1.11mg·m^-3之间，TPM基准氧含量排放浓度介于3.82~8.69mg·m^-3之间，均满足国家超低排放颗粒物限值要求（10mg·m^-3），燃煤电厂TPM排放浓度超过了北京市颗粒物排放标准限值要求（5 mg·m^-3）.燃煤供暖锅炉CPM及其总水溶性离子排放水平分别为3.05mg·m^-3和1.30mg·m^-3，显著低于燃煤电厂，与燃煤电厂的负荷和烟温较高有关；燃煤电厂锅炉CPM及其总水溶性离子排放浓度分别是燃煤供暖锅炉的2.2~2.4倍和1.7~2.2倍.燃气电厂TPM及其总水溶性离子排放水平分别为1.99mg·m^-3和1.44mg·m^-3，均明显低于燃煤锅炉.CPM是燃烧源排气中颗粒物的主要形式，在超低排放锅炉烟气中CPM对TPM的质量贡献显著增加，并随烟温的升高而增加，燃煤锅炉为72.6%~88.1%，燃气电厂为93.1%，且水溶性离子总量的66.1%~94.2%存在于CPM中.排气烟温显著影响颗粒物及其水溶性离子的赋存形态、脱除效率与排放水平.SO₄^2-是燃煤锅炉颗粒物的主要特征离子，排放浓度介于0.98~1.18mg·m^-3，占水溶性离子排放总量的27.7%~49.6%，来源于烟气脱硫；F^-是燃煤电厂颗粒物中又一主要特征离子，排放浓度介于1.91~2.32mg·m^-3，占水溶性离子排放总量的54.4%~56.1%，可能与燃料煤含氟量高有关；NH₄⁺是燃气电厂颗粒物的主要特征离子，排放浓度为0.92mg·m^-3，占水溶性离子排放总量的64.2%，来源于选择性催化还原法（selective catalytic reduction，SCR）脱硝过程中的NH₃逃逸，其排放浓度显著高于燃煤锅炉，可能与燃气电厂缺少其它净化设施的协同去除效应有关.

Emission Concentration and Characteristics of Particulate Matter and Water-Soluble Ions in Exhaust Gas of Typical Combustion Sources with Ultra-Low Emission

A self-developed direct condensation sampling system and monitoring method for total particulate matter (TPM) in ultra-low-emission and high-humidity exhaust gas were applied to the emission monitoring of particulate matter in flue gas from three typical combustion sources with ultra-low emissions in Beijing. The emission levels and composition characteristics of particulate matter and water-soluble ions in the exhaust gas of typical combustion sources with ultra-low emissions were analyzed and evaluated. The interaction and influencing factors of filterable particulate matter (FPM) and condensable particulate matter (CPM) and their water-soluble ions were explored. The results showed that the emission concentration of FPM in the exhaust gas of the coal-fired boiler with ultra-low emissions was between 1.04 mg·m^-3 and 1.11 mg·m^-3 in standard smoke oxygen content, and that of TPM was between 3.82 mg·m^-3 and 8.69 mg·m^-3, which all met the national ultra-low emission limit (10 mg·m^-3). However, the TPM emission concentration of the coal-fired power plant exceeded the emission limit of Beijing (5 mg·m^-3). The emission concentrations of CPM and its total water-soluble ions from the coal-fired heating boiler were 3.05 mg·m^-3 and 1.30 mg·m^-3, respectively, which were significantly lower than those of the coal-fired power plant, and were related to the higher load and flue gas temperature of the coal-fired power plant. Furthermore, the emission concentrations of CPM and its total water-soluble ions from the coal-fired power plant boiler were 2.2 to 2.4 times and 1.7 to 2.2 times greater than those of the coal-fired heating boiler, respectively. The emission concentrations of TPM and its total water-soluble ions from the gas power plant were 1.99 mg·m^-3 and 1.44 mg·m^-3, respectively, which were significantly lower than those from the coal-fired boiler. CPM was the main form of particulate matter in the exhaust gas of the combustion source. The contribution of CPM to TPM in the ultra-low-emission boiler flue gas increased significantly, and increased with the increase in the flue gas temperature, ranging from 72.6% to 88.1% for the coal-fired boiler and 93.1% for the gas power plant. Total water-soluble ions made up 66.1% to 94.2% of the CPM. The flue gas temperature had a significant impact on the existing forms, removal efficiencies, and emission concentrations of particulate matter and water-soluble ions. SO₄^2- was the main characteristic water-soluble ion of particulate matter in the coal-fired boiler, and its emission concentration ranged from 0.98 mg·m^-3 to 1.18 mg·m^-3, accounting for 27.7% to 49.6% of the total water-soluble ion emissions, which originated from flue gas desulfurization. F^- was another characteristic water-soluble ion of particulate matter in the coal-fired power plant, and its emission concentration ranged from 1.91 mg·m^-3 to 2.32 mg·m^-3, accounting for 54.4% to 56.1% of the total water-soluble ion emissions, which might have been related to the high F content of fuel coal. NH₄⁺ was the main characteristic water-soluble ion of particulate matter in the gas power plant, and its emission concentration was 0.92 mg·m^-3, accounting for 64.2% of the total water-soluble ion emissions, which originated from the escape of NH₃ in the process of selective catalytic reduction. The emission concentration of NH₄⁺ was significantly higher than that of the coal-fired boiler; this might have been related to the synergistic removal effect of the gas-fired power plant, which lacked other purification facilities.