燃煤烟气污染物控制装置协同脱汞特性研究
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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(Hg~0)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Hg~0和氧化态汞(Hg~(2+))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(Al_2O_3、Fe_2O_3)是吸附气态汞的关键组分,汞在飞灰表面主要以Hg Cl_2、Hg S(红色)和Hg O的形态存在,高于190℃时会分解再释放.WFGD对Hg~(2+)的平均脱除率为91.10%,并能将部分Hg~(2+)还原成Hg~0,存在明显的汞二次释放问题.
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(Hg~0)by SCR catalyst was greatly promoted by the chlorine(Cl)content in coal and 96.18%Hg~0was oxidized to oxidized mercury(Hg~(2+))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 Hg~0 and 27.79%of Hg~(2+)were observed.Unburned carbon and metal oxides(Al_2O_3,Fe_2O_3)were the main components of ESP fly ash to adsorb gaseous mercury.Hg Cl_2,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 Hg~(2+)by WFGD were 91.10%.Meanwhile,the phenomenon of mercury re-emission due to part of Hg~(2+)was reduced to Hg~0 in WFGD was found.
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(Hg~0)by SCR catalyst was greatly promoted by the chlorine(Cl)content in coal and 96.18%Hg~0was oxidized to oxidized mercury(Hg~(2+))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 Hg~0 and 27.79%of Hg~(2+)were observed.Unburned carbon and metal oxides(Al_2O_3,Fe_2O_3)were the main components of ESP fly ash to adsorb gaseous mercury.Hg Cl_2,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 Hg~(2+)by WFGD were 91.10%.Meanwhile,the phenomenon of mercury re-emission due to part of Hg~(2+)was reduced to Hg~0 in WFGD was found.
引文
[1]Wang S,Zhang L,Zhao B,et al.Mitigation potential of mercury emissions from coal-fired power plants in China[J].Energy Fuels,2012,26:4635-42.
[2]United Nations Environment Programme(UNEP)Chemicals.Global Mercury Assessment[M].Geneva,Switzerland,2002.
[3]Environmental Protection Agency.National emission standards for hazardous air pollutants from coaland oil-fired electric utility steam generating units and standards of performance for fossil-fuel-fired electricutility,industrial commercial institutional,and small industrial commercial institutional steam generating units[S].Washington,D.C:U.S.EPA,2013.
[4]GB 13223-2011火电厂大气污染物排放标准[S].
[5]DB11/139-2015锅炉大气污染物排放标准[S].
[6]Galbreath K C,Zygarlicke C J.Mercury transformations in coal combustion flue gas[J].Fuel Process Technol,2000,65-66:289-310.
[7]Tang H,Duan Y,Zhu C,et al.Theoretical evaluation on selective adsorption characteristics of alkali metal-based sorbents for gaseous oxidized mercury[J].Chemosphere,2017,184:711.
[8]朱法华,王临清.煤电超低排放的技术经济与环境效益分析[J].环境保护,2014,21:28-33.
[9]支国瑞,薛志钢,李洋,等.基于国内实测燃煤电厂烟气汞排放估算的不确定度[J].环境科学研究,2013,26(8):814-821.
[10]Wang S X,Zhang L,Li G H,et al.Mercury emission and speciation of coal-fired power plants in China[J].Atmospheric Chemistry&Physics Discussions,2010,10(3):1183-1192.
[11]Tang H,Duan Y,Zhu C,et al.Characteristics of a biomass-based sorbent trap and its application to coal-fired flue gas mercury emission monitoring[J].International Journal of Coal Geology,2017,170:19-27.
[12]Zhang Y,Yang J P,Yu X H,et al.Migration and emission characteristics of Hg in coal-fired power plant of China with ultra low emission air pollution control devices[J].Fuel Processing Technology,2017,158:272-280.
[13]段钰锋,江贻满,杨立国,等.循环流化床锅炉汞排放和吸附实验研究[J].中国电机工程学报,2008,28(32):1-5.
[14]杨立国.燃煤烟气汞形态转化及脱除机理研究[D].南京:东南大学,2008.
[15]Tang N,Pan S W.Study on mercury emission and migration from large-scale pulverized coal fired boilers[J].Journal of Fuel Chemistry&Technology,2013,41(4):484-490.
[16]Belkin H E,Finkelman R B,Zheng B.Mercury in People`s Republic of China coal[J].The Geological Society of America Abstract,2005,37(7):48.
[17]姜英.我国煤中氯的分布及其分级标准[J].煤质技术,1998,(5):7-8.
[18]Yokoyama T,Asakura k,Mastude H,et al.Mercury emissions from a coal-fired power plant in Japan[J].The Science of the Total Environment,2000,259(1-3):97-103.
[19]Zhao S,Duan Y,Yao T,et al.Study on the mercury emission and transformation in an ultra-low emission coal-fired power plant[J].Fuel,2017,199:653-661.
[20]Zhang L,Zhuo Y,Chen L,et al.Mercury emissions from six coal-fired power plants in China[J].Fuel Process Technol,2008,89(11):1033-1040.
[21]Pudasainee D,Kim J H,Yoon Y S,et al.Oxidation,reemission and mass distribution of mercury in bituminous coal-fired power plants with SCR,CS-ESP and wet FGD[J].Fuel,93(2012):312-318.
[22]巴蓓.燃煤飞灰热处理过程中汞的释放特征及机理分析[D].广州:华南理工大学,2012.
[23]Bhardwaj R,Chen X H,Vidic R D.Impact of fly ash composition on mercury speciation in simulated flue gas[J].Air Waste Management Association,2009,59:1331-1338.
[24]Wang F Y,Wang S X,Meng Y,et al.Mechanisms and roles of fly ash composition on the adsorption and oxidation of mercury in flue gas from coal combustion[J].Fuel,2016,163:232-239.
[25]Lee C W,Kilgroe J D,Ghorishi S B.Mercury control research:Effects of fly ash and flue gas parameters on mercury speciation[J].Fuel&Energy Abstracts,1998,43(1):70-71.
[26]Lopze-antona M A,Perry R,Abad-valle P,et al.Speciation of mercury in fly ashes by temperature programmed decomposition[J].Fuel Processing Technology,2011,92(3):707-711.
[27]周强.改性吸附剂喷射脱汞的实验及机理研究[D].南京:东南大学,2016.
[28]Chang J C,Ghorish S B.Simulation and evaluation of elemental mercury concentration increase in flue gas across a wet scrubber[J].Environ Sci Technol,2003,37(24):5763-5766.
[29]李志超,段钰锋,王运军,等.300MW燃煤电厂ESP和WFGD对烟气汞的脱除特性[J].燃料化学学报,2013,41(4):491-498.
[2]United Nations Environment Programme(UNEP)Chemicals.Global Mercury Assessment[M].Geneva,Switzerland,2002.
[3]Environmental Protection Agency.National emission standards for hazardous air pollutants from coaland oil-fired electric utility steam generating units and standards of performance for fossil-fuel-fired electricutility,industrial commercial institutional,and small industrial commercial institutional steam generating units[S].Washington,D.C:U.S.EPA,2013.
[4]GB 13223-2011火电厂大气污染物排放标准[S].
[5]DB11/139-2015锅炉大气污染物排放标准[S].
[6]Galbreath K C,Zygarlicke C J.Mercury transformations in coal combustion flue gas[J].Fuel Process Technol,2000,65-66:289-310.
[7]Tang H,Duan Y,Zhu C,et al.Theoretical evaluation on selective adsorption characteristics of alkali metal-based sorbents for gaseous oxidized mercury[J].Chemosphere,2017,184:711.
[8]朱法华,王临清.煤电超低排放的技术经济与环境效益分析[J].环境保护,2014,21:28-33.
[9]支国瑞,薛志钢,李洋,等.基于国内实测燃煤电厂烟气汞排放估算的不确定度[J].环境科学研究,2013,26(8):814-821.
[10]Wang S X,Zhang L,Li G H,et al.Mercury emission and speciation of coal-fired power plants in China[J].Atmospheric Chemistry&Physics Discussions,2010,10(3):1183-1192.
[11]Tang H,Duan Y,Zhu C,et al.Characteristics of a biomass-based sorbent trap and its application to coal-fired flue gas mercury emission monitoring[J].International Journal of Coal Geology,2017,170:19-27.
[12]Zhang Y,Yang J P,Yu X H,et al.Migration and emission characteristics of Hg in coal-fired power plant of China with ultra low emission air pollution control devices[J].Fuel Processing Technology,2017,158:272-280.
[13]段钰锋,江贻满,杨立国,等.循环流化床锅炉汞排放和吸附实验研究[J].中国电机工程学报,2008,28(32):1-5.
[14]杨立国.燃煤烟气汞形态转化及脱除机理研究[D].南京:东南大学,2008.
[15]Tang N,Pan S W.Study on mercury emission and migration from large-scale pulverized coal fired boilers[J].Journal of Fuel Chemistry&Technology,2013,41(4):484-490.
[16]Belkin H E,Finkelman R B,Zheng B.Mercury in People`s Republic of China coal[J].The Geological Society of America Abstract,2005,37(7):48.
[17]姜英.我国煤中氯的分布及其分级标准[J].煤质技术,1998,(5):7-8.
[18]Yokoyama T,Asakura k,Mastude H,et al.Mercury emissions from a coal-fired power plant in Japan[J].The Science of the Total Environment,2000,259(1-3):97-103.
[19]Zhao S,Duan Y,Yao T,et al.Study on the mercury emission and transformation in an ultra-low emission coal-fired power plant[J].Fuel,2017,199:653-661.
[20]Zhang L,Zhuo Y,Chen L,et al.Mercury emissions from six coal-fired power plants in China[J].Fuel Process Technol,2008,89(11):1033-1040.
[21]Pudasainee D,Kim J H,Yoon Y S,et al.Oxidation,reemission and mass distribution of mercury in bituminous coal-fired power plants with SCR,CS-ESP and wet FGD[J].Fuel,93(2012):312-318.
[22]巴蓓.燃煤飞灰热处理过程中汞的释放特征及机理分析[D].广州:华南理工大学,2012.
[23]Bhardwaj R,Chen X H,Vidic R D.Impact of fly ash composition on mercury speciation in simulated flue gas[J].Air Waste Management Association,2009,59:1331-1338.
[24]Wang F Y,Wang S X,Meng Y,et al.Mechanisms and roles of fly ash composition on the adsorption and oxidation of mercury in flue gas from coal combustion[J].Fuel,2016,163:232-239.
[25]Lee C W,Kilgroe J D,Ghorishi S B.Mercury control research:Effects of fly ash and flue gas parameters on mercury speciation[J].Fuel&Energy Abstracts,1998,43(1):70-71.
[26]Lopze-antona M A,Perry R,Abad-valle P,et al.Speciation of mercury in fly ashes by temperature programmed decomposition[J].Fuel Processing Technology,2011,92(3):707-711.
[27]周强.改性吸附剂喷射脱汞的实验及机理研究[D].南京:东南大学,2016.
[28]Chang J C,Ghorish S B.Simulation and evaluation of elemental mercury concentration increase in flue gas across a wet scrubber[J].Environ Sci Technol,2003,37(24):5763-5766.
[29]李志超,段钰锋,王运军,等.300MW燃煤电厂ESP和WFGD对烟气汞的脱除特性[J].燃料化学学报,2013,41(4):491-498.