基于Ontario Hydro方法的贵州省人为源大气汞排放特征研究

Mercury is a global pollutant due to its long life in the atmosphere. Coal-fired power plant and Zinc smelting plant are the main anthropogenic atmospheric mercury sources in Guizhou province. Research on the characteristics of anthropogenic atmospheric mercury emissions in Guizhou province can be of significant importance for the establishment and updates of emission inventory of anthropogenic atmospheric mercury and policy-making of mercury pollution control in China, especially in Guizhou. Here, several research works are carried out as follows： 1. The characteristics of mercury emission from coal-fired power plant in Guizhou The percentage of Hg0 constitutes more than 70% in the exhaust of coal-fired power plants and Hg0 is the main species in the exhaust air. Using the U.S. Materials Society Ontario Hydro method, on-site monitoring and investigations and mercury emissions characteristics analysis for 200MW, 300MW, 600MW coal-fired power plant would be carried out in Guizhou Province, as well as the mercury removal efficiency evaluation in typical 200MW unit equipped with SCR, 100MW unit equipped with circulating fluidized bed (CBF-FGD) and fabric filter bag houses. 2. The characteristics of mercury emission from Zinc smelting plant in Guizhou Using the modified EPA Method 29, combined with Ontario Hydro method, the exhaust gas released from roasting (sintering) process in zinc smelter by hydrometallurgy and sulfuric acid fumes, drying kiln exhaust, flue gas in head of sintering machine released from pyro-metallurgical ISP are performed to investigate the different morphology, mercury removal efficiency and emission characteristics in Zinc smelting plant. 3. Estimation of mercury emission from anthropogenic sources in Guizhou The mercury emission factor in coal-fired power plant, industrial boilers and Zinc smelting plant are estimated based on emission factor method and the Ontario Hydro method. Anthropogenic sources of atmospheric mercury emission are estimated for the establishment of the emission inventory of Guizhou Province and serve for the mercury prediction in the future.

汞是全球性污染物。燃煤电厂和锌冶炼厂是贵州最主要大气排汞源。经现场测试，开展以下研究：1. 贵州省燃煤电厂大气汞排放特征。燃煤电厂尾气排放汞的形态以元素汞为主，占到70%以上。运用Ontario Hydro方法，开展贵州省内200MW、300MW、600MW燃煤电厂汞的排放特征，以及200MW配备SCR，100MW配备循环流化床（CBF-FGD）和布袋除尘器后，燃煤电厂的联合脱汞效率研究。2. 贵州省锌冶炼厂大气汞排放特征。运用改进的EPA Method 29方法，结合Ontario Hydro方法，对湿法配备烟气汞回收和火法ISP工艺大型炼锌厂焙烧（烧结）制酸烟气、干燥窑尾气、烧结机头烟气中气态汞的不同形态、脱汞效率与排放特征开展研究。3.贵州省人为源大气汞排放估算。采用排放因子法和Ontario Hydro方法对贵州省人为源大气排汞进行估算，建立大气汞排放预测机制并编制贵州省排放清单。

汞是全球性污染物。燃煤电厂和锌冶炼厂是贵州最主要大气排汞源。经现场测试，开展以下研究：1.贵州省燃煤电厂大气汞排放特征及脱汞效率研究。2.贵州省锌冶炼厂大气汞排放特征及烟气中气态汞的不同形态、脱汞效率开展研究。3.燃煤飞灰理化特征与汞吸附量相关分析。4.贵州省人为源大气汞排放估算并编制贵州省排放清单。项目的主要结论如下：1.贵州电厂煤种汞含量高，汞含量随灰分含量增加而升高；烟气总汞去除率在57%-69%之间，略低于发达国家电厂烟气中总汞脱除率，最终排放到大气中汞以Hg0为主。2.具有制酸工艺的炼锌厂对大气汞排放主要位于干燥窑尾气、挥发窑尾气和烧结机头尾气；烟气净化设备脱汞率为17.0-17.7%；电除雾器脱汞率为21.0-42.2%；脱汞塔脱汞率为82.8-92.1%；制酸过程对烟气汞的去除率为96.5－97.8%。3.电厂和冶炼厂向大气排放不同形态的汞，其组成明显不同。电厂Hg0 比例63%-88%，Hg2+比例其次，Hgp比例小于0.1%；冶炼厂比例组成Hg2+ 82%-90% ，Hg0 6%-12%，Hgp 4%-6%。4.通过数据统计分析，贵州省国控企业汞及其汞化合物均可达标排放，其中水泥行业、冶金矿产行业、化工行业和电力行业等对大气汞污染源排放都有贡献值。5.江苏电厂烟气中汞浓度为3.197μg/m3，汞去除率达80%，汞含量和浓度明显降低。省内外电厂对比，各省汞排放水平总体接近于发达国家。6.通过燃煤飞灰理化特征分析，同一电厂粗灰和细灰的无机组成基本相同，未燃尽碳含量不同；细灰的烧失量、比表面积、汞吸附量均是粗灰的两倍左右；比表面积与烧失量成正比，汞吸附量与比表面积正相关。7.燃煤飞灰中的汞以不同汞化合物存在，包括HgCl2（Hg2Cl2）、黑色HgS 和HgO。部分飞灰的汞化合物类型只有黑色HgS 和HgO。8.应用排放因子法对贵州省大气汞排放清单进行了修正，贵州省大气汞与该地区人为源汞排放量的变化一致；汞开采、水泥行业、燃煤电厂、燃煤工业锅炉、住宅锅炉及其他相关化工企业依然为大气汞的主要人为排放源。研究成果不仅可以帮助企业改善燃煤样的选择和排放量的控制，还可以帮助政府确定适合本地区的大气污染控制政策。