某660 MW燃煤发电机组汞的迁移排放特性研究

Migration and Emission Characteristics of Mercury in 660 MW Coal-Fired Power Plant

为研究某660 MW燃煤发电机组汞的迁移排放特性,采用安大略法对烟气进行采样,并对煤、灰、石膏、废水等物质中的汞含量进行了测定。结果表明:入炉煤中汞的质量浓度为0.154 mg/kg。本次测试汞的质量平衡率为91.07%。燃煤电厂汞主要通过飞灰(40.57%)、脱硫石膏(32.01%)和烟气(27.02%)排放至环境中。SCR系统对Hg^(0)的氧化率为54.38%,空预器会促进Hg^(0)和Hg^(2+)向Hg^(p)转化,除尘器对Hg^(p)的去除率为99.89%,FGD对Hg^(2+)的去除率为86.14%。全系统对Hg^(T)的脱除效率为71.85%。通过烟气排放至大气中的汞浓度为3.99μg/m^(3),满足《火电厂大气污染物排放标准》(GB/T 13223)的要求。

In order to study the mercury migration and emission characteristics of a 660 MW coal-fired generating unit,the Ontario method was adopted to sample the flue gas,and the mercury content in coal,ash,gypsum,wastewater and other substances was tested.According to the results,the mass concentration of mercury in the furnace coal was 0.154 mg/kg,the mass balance rate of mercury in this test was 91.07% and mercury is mainly emitted from coal-fired power plants through fly ash(40.57%),desulphurized gypsum(32.01%)and flue gas(27.02%).The results also showed that the oxidation rate of Hg^(0) by SCR system was 54.38% and the air preheater would promote the conversion of Hg^(0) and Hg^(2+)to Hg^(p).The dust collector removed 99.89% of Hg^(p) and FGD removed 86.14% of Hg^(2+).The removal efficiency of Hg^(T) by the system was 71.85%.The concentration of mercury emitted into the air through the flue gas is 3.99μg/m^(3),which meets the requirements of Emission Standard of Air Pollutants for Thermal Power Plants(GB/T 13223).