【摘要】 采用Ontario Hydro方法对某100MW燃煤机组进行了烟气汞取样测试,获得了选择性催化还原（SCR）脱硝装置、静电除尘器（ESP）和湿法烟气脱硫装置（WFGD）对烟气汞形态转化和脱除特性规律.借助程序升温脱附（TPD）、扫描电子显微镜分析（SEM）和X射线荧光光谱分析（XRF）等方法探究了飞灰对汞的吸附特性及吸附后汞的热稳定性.结果表明,在75%MCR和85%MCR不同的机组负荷下,SCR+ESP+WFGD对烟气总汞（Hg^T）的联合脱除率分别为92.83%、81.66%.SCR对元素汞（Hg⁰）的氧化率与燃煤氯（Cl）含量正相关,Cl含量为500mg/kg时,氧化率高达96.18%.ESP在完全脱除颗粒汞（Hg^P）的同时对Hg⁰和氧化态汞(Hg²⁺)的平均脱除率分别为12.73%和27.79%,ESP飞灰中的未燃尽炭和金属氧化物（Al₂O₃、Fe₂O₃）是吸附气态汞的关键组分,汞在飞灰表面主要以Hg Cl₂、Hg S（红色）和Hg O的形态存在,高于190℃时会分解再释放.WFGD对Hg²⁺的平均脱除率为91.10%,并能将部分Hg²⁺还原成Hg⁰,存在明显的汞二次释放问题.更多还原

【Abstract】 The Ontario Hydro Method（OHM）was applied to determine the mercury speciation and concentration in the flue gas emitted from a 100MW boiler system.Mercury speciation transformation and removal characteristics of selective catalytic reduction（SCR）system,electrostatic precipitators（ESP）and wet flue gas desulfurization（WFGD）had been obtained.Temperature programmed decomposition（TPD）,Scanning electron microscope（SEM）and X ray fluorescence（XRF）were used to investigate the adsorption characteristic of mercury by fly ashes and thermal stability after adsorption.The results show that the overall mercury（Hg^T）removal efficiencies over SCR+ESP+WFGD combination were92.83%and 81.66%under 75%MCR and 85%MCR,respectively.The oxidation of element mercury（Hg⁰）by SCR catalyst was greatly promoted by the chlorine（Cl）content in coal and 96.18%Hg⁰was oxidized to oxidized mercury(Hg²⁺)by SCR when the Cl concentration in burned-coal contained 500mg/kg.Hg^P could be effectively removed by ESP,removal efficiencies with 12.73%of Hg⁰ and 27.79%of Hg²⁺were observed.Unburned carbon and metal oxides（Al₂O₃,Fe₂O₃）were the main components of ESP fly ash to adsorb gaseous mercury.Hg Cl₂,Hg S（red）,and Hg O were the main mercury compounds in the ash after adsorption which would decompose when the temperature reached 190 degrees.The average removal efficiencies of Hg²⁺by WFGD were 91.10%.Meanwhile,the phenomenon of mercury re-emission due to part of Hg²⁺was reduced to Hg⁰ in WFGD was found.更多还原