燃煤电厂大气重金属排放控制策略

Emission Control Strategies of Atmospheric Heavy Metals for Coal-fired Power Plants

燃煤是人为源大气重金属的主要排放源,为制定适合我国燃煤电厂且经济高效的大气重金属排放控制策略,该文系统分析我国原煤中6种重金属(Hg、As、Pb、Se、Cd、Cr)的含量和分布特征,以及燃煤电厂大气重金属排放控制措施,建立最佳可行技术/最佳环境实践(best available technique/best environment practice,BAT/BEP)的决策树模型,并评估不同BAT/BEP控制策略的大气重金属减排效果。结果表明:燃煤电厂大气重金属排放与煤质、炉型、常规烟气污染物控制设备(air pollution control devices,APCDs)组合等显著相关。对于安装选择性催化还原(selective catalytic reduction,SCR)脱硝+静电除尘器(eletrostatic precipitator,ESP)+湿法烟气脱硫(wet flue gas desulfurization,WFGD)(或+湿式静电除尘器(wet electrostatic precipitator,WESP))组合的超低排放或近零排放燃煤机组,改性飞灰专门脱汞技术对大气汞深度脱除效果最显著,适用范围广泛;强化协同控制技术(APCDs提效)对其他大气重金属(As、Pb、Se、Cd、Cr)的深度脱除效果最显著。

Coal combustion is the most important source of anthropogenic atmospheric releases of heavy metals.To develop the economical and efficient emission control strategies of atmospheric heavy metals suitable for coal-fired power plants in China,this paper systematically analyzes the main characteristics of 6 concerning heavy metals(Hg,As,Pb,Se,Cd and Cr)in Chinese coal in relation to their content,distribution,and emission control measure.Particularly,the best available technique(BAT)and best environment practice(BEP)decision tree models for each technological option of heavy metals emission control are established,and the emission reduction effects for different BAT/BEP control strategies are evaluated.The results show that the atmospheric heavy metals emissions from coal-fired power plants are significantly correlated with coal property,boiler type,and air pollution control devices(APCDs).For the ultra-low or near-zero emission units equipped with selective catalytic reduction(SCR)+eletrostatic precipitator(ESP)+wet flue gas desulfurization(WFGD)(+WESP),the modified fly ash specialized mercury removal technology and enhancement of synergistic control technologies exhibit significant effects on the deep removal of atmospheric Hg and other 5 heavy metals(As,Pb,Se,Cd and Cr),respectively.