基于实测的300 MW燃煤发电机组大气汞排放特征分析

Mercury Emission Characteristics from Coal-Fired 300 MW Generating Units Based on Measurements

对我国西南地区某燃煤电厂300 MW发电机组进行实测,依据实测结果对静电除尘装置(ESP)及湿法脱硫系统(WFGD)脱汞率进行分析.结果表明:目前已知测试过的绝大多数燃煤电厂大气汞排放质量浓度都低于《火电厂大气污染物排放标准》(GB13223-2011)中30μg/m3的标准限值.生产工况对燃煤电厂大气汞排放浓度的影响程度大于燃煤中汞含量对其影响的程度,且当生产工况大于98%时总汞排放浓度明显高于其他工况下排放浓度.ESP既脱除颗粒态汞也脱除气态汞,脱汞率较稳定,均值为90.0%;而WFGD脱汞率不稳定,脱汞率最低为42.8%,最高为96.6%,均值为75.0%.

Actual measurement was conducted on a 300 MW generator unit in a coalfired power plant in the southwest of China. On the basis of the measurement results, the mercury removal rate of the ESP and WFGD was analyzed. The results show that the mercury emission concentration into the atmosphere in most coalfired power plants that have undergone tests is below the standard limit of 30 μg/m3 as regulated in Emission Standard of Air Pollutants for Thermal Power Plants （GB132232011）. Compared with the mercury content in the fuel coal, production conditions have greater influence on the mercury emission concentration into the atmosphere from the coalfired power plants, and when the production conditions are more than 98%, the total mercury emission concentration is significantly higher than that under other conditions. ESP removes both particle mercury and gaseous mercury with a stable mercury removal rate of 90.0% on average. By contrast, WFGD has an unstable mercury removal rate of 75.0% on average, ranging from 42.8% to 96.6%.