Effects of temperature and SO_3 on re-emission of mercury from activated carbon under flue gas conditions
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摘要
Mercury(Hg) is a toxic and bio-accumulating heavy metal that is predominantly released via the combustion of coal. Due to its toxicity, the Environmental Protection Agency(EPA)has introduced Mercury and Air Toxics Standards(MATS) Rule regarding allowable Hg emissions. In order to reduce emissions, power plants have widely adopted activated carbon(AC) injection. AC injection has proven to be an effective method to reduce Hg emissions, but the re-emission of previously adsorbed Hg during unit operation, likely due to changing temperature or flue gas composition, could be problematic. This study specifically examined the effects of temperature and sulfur trioxide(SO3) concentration,by ramping temperature and SO3 concentration independently and simultaneously, on AC samples that are already exposed to flue gas and saturated in presence of Hg, sulfur dioxide(SO2) and nitric oxide(NO). Of these two suspected factors to cause re-emission,temperature had the greater impact and resulted in re-emission of both elemental and oxidized Hg with a greater fraction of oxidized Hg, which can be attributed to elemental Hg being more strongly bonded to the AC surface. Surprisingly, exposing the samples to increasing concentrations of SO3 had nearly no effect under the conditions examined in this study, possibly as a result of the samples being already saturated with sulfur prior to the SO3 ramp tests to simulate transient conditions in the plant.
Mercury(Hg) is a toxic and bio-accumulating heavy metal that is predominantly released via the combustion of coal. Due to its toxicity, the Environmental Protection Agency(EPA)has introduced Mercury and Air Toxics Standards(MATS) Rule regarding allowable Hg emissions. In order to reduce emissions, power plants have widely adopted activated carbon(AC) injection. AC injection has proven to be an effective method to reduce Hg emissions, but the re-emission of previously adsorbed Hg during unit operation, likely due to changing temperature or flue gas composition, could be problematic. This study specifically examined the effects of temperature and sulfur trioxide(SO3) concentration,by ramping temperature and SO3 concentration independently and simultaneously, on AC samples that are already exposed to flue gas and saturated in presence of Hg, sulfur dioxide(SO2) and nitric oxide(NO). Of these two suspected factors to cause re-emission,temperature had the greater impact and resulted in re-emission of both elemental and oxidized Hg with a greater fraction of oxidized Hg, which can be attributed to elemental Hg being more strongly bonded to the AC surface. Surprisingly, exposing the samples to increasing concentrations of SO3 had nearly no effect under the conditions examined in this study, possibly as a result of the samples being already saturated with sulfur prior to the SO3 ramp tests to simulate transient conditions in the plant.
Mercury(Hg) is a toxic and bio-accumulating heavy metal that is predominantly released via the combustion of coal. Due to its toxicity, the Environmental Protection Agency(EPA)has introduced Mercury and Air Toxics Standards(MATS) Rule regarding allowable Hg emissions. In order to reduce emissions, power plants have widely adopted activated carbon(AC) injection. AC injection has proven to be an effective method to reduce Hg emissions, but the re-emission of previously adsorbed Hg during unit operation, likely due to changing temperature or flue gas composition, could be problematic. This study specifically examined the effects of temperature and sulfur trioxide(SO3) concentration,by ramping temperature and SO3 concentration independently and simultaneously, on AC samples that are already exposed to flue gas and saturated in presence of Hg, sulfur dioxide(SO2) and nitric oxide(NO). Of these two suspected factors to cause re-emission,temperature had the greater impact and resulted in re-emission of both elemental and oxidized Hg with a greater fraction of oxidized Hg, which can be attributed to elemental Hg being more strongly bonded to the AC surface. Surprisingly, exposing the samples to increasing concentrations of SO3 had nearly no effect under the conditions examined in this study, possibly as a result of the samples being already saturated with sulfur prior to the SO3 ramp tests to simulate transient conditions in the plant.
引文
Bolate,Y.,2017.Inventory of US Sources of Mercury Emissions to the Atmosphere.Columbia University.
Carey,T.R.,Jr,O.W.H.,Richardson,C.F.,Chang,R.,Meserole,F.B.,1998.Factors affecting mercury control in utility flue gas using activated carbon.J.Air Waste Manage.Assoc.48,1166-1174.
De,M.,Azargohar,R.,Dalai,A.K.,Shewchuk,S.R.,2013.Mercury removal by bio-char based modified activated carbons.Fuel103,570-578.
EIA(Energy Information Admistration),2018.Electric Power monthly.Available:https://www.eia.gov/electricity/monthly/archive/february2018.pdf.Accessed:August 30,2018.
EPRI,2015.Utility Pulse Jet Baghouse Performance 2015 Update,3002006153.Palo Alto,CA.
Eswaran,S.,Stenger,H.G.,2005.Understanding mercury conversion in selective catalytic reduction(SCR)catalysts.Energy Fuel 19,2328-2334.
Ghorishi,S.B.,Sedman,C.B.,1998.Low concentration mercury sorption mechanisms and control by calcium-based sorbents:application in coal-fired processes.J.Air Waste Manage.Assoc.48,1191-1198.
Granite,Evan J.,Hargis,R.A.,Pennline,Henry W.,1998.Sorbents for mercury removal from flue gas.Federal Energy Technology Center,Pittsburgh https://www.osti.gov/scitech/biblio/1165/.
Granite,E.J.,Pennline,H.W.,Hargis,R.A.,2000.Novel sorbents for mercury removal from flue gas.Ind.Eng.Chem.Res.39,1020-1029.
Granite,E.J.,Freeman,M.C.,Hargis,R.A.,O'Dowd,W.J.,Pennline,H.W.,2007.The thief process for mercury removal from flue gas.J.Environ.Manag.84,628-634.
Granite,E.J.,Pennline,H.W.,Senior,C.,2015.Mercury control:For coal-derived gas streams.John Wiley&Sons.
Ho,T.C.,Yang,P.,Kuo,T.H.,Hopper,J.R.,1998.Characteristics of mercury desorption from sorbents at elevated temperatures.Waste Manag.18,445-452.
Kamata,H.,Ueno,S.-i.,Sato,N.,Naito,T.,2009.Mercury oxidation by hydrochloric acid over Ti O2 supported metal oxide catalysts in coal combustion flue gas.Fuel Process.Technol.90,947-951.
Kampa,M.,Castanas,E.,2008.Human health effects of air pollution.Environ.Pollut.151,362-367.
Korpiel,J.A.,Vidic,R.D.,1997.Effect of sulfur impregnation method on activated carbon uptake of gas-phase mercury.Environ.Sci.Technol.31,2319-2325.
Li,Y.,Duan,Y.,Wang,H.,Zhao,S.,Chen,M.,Liu,M.,et al.,2017.Effects of acidic gases on mercury adsorption by activated carbon in simulated oxy-fuel combustion flue gas.Energy Fuel31,9745-9751.
Luo,Z.,Hu,C.,Zhou,J.,Cen,K.,2006.Stability of mercury on three activated carbon sorbents.Fuel Process.Technol.87,679-685.
Miller,S.J.,Dunham,G.E.,Olson,E.S.,Brown,T.D.,2000.Flue gas effects on a carbon-based mercury sorbent.Fuel Process.Technol.65-66,343-363.
Min,H.,Ahmad,T.,Lee,S.-S.,2017.Mercury adsorption characteristics as dependent upon the physical properties of activated carbon.Energy Fuel 31,724-729.
Mullett,M.,Pendleton,P.,Badalyan,A.,2012.Removal of elemental mercury from Bayer stack gases using sulfurimpregnated activated carbons.Chem.Eng.J.211-212,133-142.
Ochiai,R.,Uddin,M.A.,Sasaoka,E.,Wu,S.,2009.Effects of HCl and SO2 concentration on mercury removal by activated carbon sorbents in coal-derived flue gas.Energy Fuel 23,4734-4739.
Olson,E.S.,Crocker,C.R.,Benson,S.A.,Pavlish,J.H.,Holmes,M.J.,2005.Surface compositions of carbon sorbents exposed to simulated low-rank coal flue gases.J.Air Waste Manage.Assoc.55,747-754.
Presto,A.A.,Granite,E.J.,2007.Impact of sulfur oxides on mercury capture by activated carbon.Environ.Sci.Technol.41,6579-6584.
Presto,A.A.,Granite,E.J.,2008.Noble metal catalysts for mercury oxidation in utility flue gas.Platin.Met.Rev.52,144-154.
Presto,A.A.,Granite,E.J.,Karash,A.,2007.Further investigation of the impact of sulfur oxides on mercury capture by activated carbon.Ind.Eng.Chem.Res.46,8273-8276.
Qiao,S.,Chen,J.,Li,J.,Qu,Z.,Liu,P.,Yan,N.,et al.,2009.Adsorption and catalytic oxidation of gaseous elemental mercury in flue gas over Mn Ox/Alumina.Ind.Eng.Chem.Res.48,3317-3322.
Ralston,N.,2008.Nanomaterials:Nano-selenium captures mercury.Nat.Nanotech.3,527.
Rice,K.M.,Walker,E.M.,Wu,M.,Gillette,C.,Blough,E.R.,2014.Environmental mercury and its toxic effects.J.Prev.Med.Public Health 47,74-83.
Rumayor,M.,Lopez-Anton,M.A.,Díaz-Somoano,M.,MartínezTarazona,M.R.,2015.A new approach to mercury speciation in solids using a thermal desorption technique.Fuel 160,525-530.
Rungnim,C.,Promarak,V.,Hannongbua,S.,Kungwan,N.,Namuangruk,S.,2016.Complete reaction mechanisms of mercury oxidation on halogenated activated carbon.J.Hazard.Mater.310,253-260.
Rupp,E.C.,Wilcox,J.,2014.Mercury chemistry of brominated activated carbons-Packed-bed breakthrough experiments.Fuel 117,351-353.
Sano,A.,Takaoka,M.,Shiota,K.,2017.Vapor-phase elemental mercury adsorption by activated carbon co-impregnated with sulfur and chlorine.Chem.Eng.J.315,598-607.
Sasmaz,E.,Kirchofer,A.,Jew,A.D.,Saha,A.,Abram,D.,Jaramillo,T.F.,et al.,2012.Mercury chemistry on brominated activated carbon.Fuel 99,188-196.
Senior,C.,Denison,M.,Bockelie,M.,Sarofim,A.,Siperstein,J.,He,Q.,2010.Modeling of thermal desorption of Hg from activated carbon.Fuel Process.Technol.91,1282-1287.
Sjostrom,S.,Dillon,M.,Donnelly,B.,Bustard,J.,Filippelli,G.,Glesmann,R.,et al.,2009.Influence of SO3on mercury removal with activated carbon:Full-scale results.Fuel Process.Technol.90,1419-1423.
Sun,P.,Zhang,B.,Zeng,X.,Luo,G.,Li,X.,Yao,H.,et al.,2017.Deep study on effects of activated carbon's oxygen functional groups for elemental mercury adsorption using temperature programmed desorption method.Fuel 200,100-106.
Tan,Z.,Xiang,J.,Su,S.,Zeng,H.,Zhou,C.,Sun,L.,et al.,2012.Enhanced capture of elemental mercury by bamboo-based sorbents.J.Hazard.Mater.239-240,160-166.
U.S.EPA(United States Environmental Protection Agency),2011.Mercury and Air Toxics Standards(MATS).Available:.https://www.epa.gov/mats,Accessed date:30 April 2018.
Vainio,E.,Fleig,D.,Brink,A.,Andersson,K.,Johnsson,F.,Hupa,M.,2013.Experimental evaluation and field application of a salt method for SO3 measurement in flue gases.Energy Fuel 27,2767-2775.
Yan,R.,Ng,Y.L.,Liang,D.T.,Lim,C.S.,Tay,J.H.,2003.Bench-scale experimental study on the effect of flue gas composition on mercury removal by activated carbon adsorption.Energy Fuel17,1528-1535.
Zhou,Q.,Duan,Y.,Chen,M.,Liu,M.,Lu,P.,2017.Studies on mercury adsorption species and equilibrium on activated carbon surface.Energy Fuel 31,14211-14218.
Zhu,C.,Duan,Y.,Wu,C.-Y.,Zhou,Q.,She,M.,Yao,T.,et al.,2016.Mercury removal and synergistic capture of SO2/NO by ammonium halides modified rice husk char.Fuel 172,160-169.
Carey,T.R.,Jr,O.W.H.,Richardson,C.F.,Chang,R.,Meserole,F.B.,1998.Factors affecting mercury control in utility flue gas using activated carbon.J.Air Waste Manage.Assoc.48,1166-1174.
De,M.,Azargohar,R.,Dalai,A.K.,Shewchuk,S.R.,2013.Mercury removal by bio-char based modified activated carbons.Fuel103,570-578.
EIA(Energy Information Admistration),2018.Electric Power monthly.Available:https://www.eia.gov/electricity/monthly/archive/february2018.pdf.Accessed:August 30,2018.
EPRI,2015.Utility Pulse Jet Baghouse Performance 2015 Update,3002006153.Palo Alto,CA.
Eswaran,S.,Stenger,H.G.,2005.Understanding mercury conversion in selective catalytic reduction(SCR)catalysts.Energy Fuel 19,2328-2334.
Ghorishi,S.B.,Sedman,C.B.,1998.Low concentration mercury sorption mechanisms and control by calcium-based sorbents:application in coal-fired processes.J.Air Waste Manage.Assoc.48,1191-1198.
Granite,Evan J.,Hargis,R.A.,Pennline,Henry W.,1998.Sorbents for mercury removal from flue gas.Federal Energy Technology Center,Pittsburgh https://www.osti.gov/scitech/biblio/1165/.
Granite,E.J.,Pennline,H.W.,Hargis,R.A.,2000.Novel sorbents for mercury removal from flue gas.Ind.Eng.Chem.Res.39,1020-1029.
Granite,E.J.,Freeman,M.C.,Hargis,R.A.,O'Dowd,W.J.,Pennline,H.W.,2007.The thief process for mercury removal from flue gas.J.Environ.Manag.84,628-634.
Granite,E.J.,Pennline,H.W.,Senior,C.,2015.Mercury control:For coal-derived gas streams.John Wiley&Sons.
Ho,T.C.,Yang,P.,Kuo,T.H.,Hopper,J.R.,1998.Characteristics of mercury desorption from sorbents at elevated temperatures.Waste Manag.18,445-452.
Kamata,H.,Ueno,S.-i.,Sato,N.,Naito,T.,2009.Mercury oxidation by hydrochloric acid over Ti O2 supported metal oxide catalysts in coal combustion flue gas.Fuel Process.Technol.90,947-951.
Kampa,M.,Castanas,E.,2008.Human health effects of air pollution.Environ.Pollut.151,362-367.
Korpiel,J.A.,Vidic,R.D.,1997.Effect of sulfur impregnation method on activated carbon uptake of gas-phase mercury.Environ.Sci.Technol.31,2319-2325.
Li,Y.,Duan,Y.,Wang,H.,Zhao,S.,Chen,M.,Liu,M.,et al.,2017.Effects of acidic gases on mercury adsorption by activated carbon in simulated oxy-fuel combustion flue gas.Energy Fuel31,9745-9751.
Luo,Z.,Hu,C.,Zhou,J.,Cen,K.,2006.Stability of mercury on three activated carbon sorbents.Fuel Process.Technol.87,679-685.
Miller,S.J.,Dunham,G.E.,Olson,E.S.,Brown,T.D.,2000.Flue gas effects on a carbon-based mercury sorbent.Fuel Process.Technol.65-66,343-363.
Min,H.,Ahmad,T.,Lee,S.-S.,2017.Mercury adsorption characteristics as dependent upon the physical properties of activated carbon.Energy Fuel 31,724-729.
Mullett,M.,Pendleton,P.,Badalyan,A.,2012.Removal of elemental mercury from Bayer stack gases using sulfurimpregnated activated carbons.Chem.Eng.J.211-212,133-142.
Ochiai,R.,Uddin,M.A.,Sasaoka,E.,Wu,S.,2009.Effects of HCl and SO2 concentration on mercury removal by activated carbon sorbents in coal-derived flue gas.Energy Fuel 23,4734-4739.
Olson,E.S.,Crocker,C.R.,Benson,S.A.,Pavlish,J.H.,Holmes,M.J.,2005.Surface compositions of carbon sorbents exposed to simulated low-rank coal flue gases.J.Air Waste Manage.Assoc.55,747-754.
Presto,A.A.,Granite,E.J.,2007.Impact of sulfur oxides on mercury capture by activated carbon.Environ.Sci.Technol.41,6579-6584.
Presto,A.A.,Granite,E.J.,2008.Noble metal catalysts for mercury oxidation in utility flue gas.Platin.Met.Rev.52,144-154.
Presto,A.A.,Granite,E.J.,Karash,A.,2007.Further investigation of the impact of sulfur oxides on mercury capture by activated carbon.Ind.Eng.Chem.Res.46,8273-8276.
Qiao,S.,Chen,J.,Li,J.,Qu,Z.,Liu,P.,Yan,N.,et al.,2009.Adsorption and catalytic oxidation of gaseous elemental mercury in flue gas over Mn Ox/Alumina.Ind.Eng.Chem.Res.48,3317-3322.
Ralston,N.,2008.Nanomaterials:Nano-selenium captures mercury.Nat.Nanotech.3,527.
Rice,K.M.,Walker,E.M.,Wu,M.,Gillette,C.,Blough,E.R.,2014.Environmental mercury and its toxic effects.J.Prev.Med.Public Health 47,74-83.
Rumayor,M.,Lopez-Anton,M.A.,Díaz-Somoano,M.,MartínezTarazona,M.R.,2015.A new approach to mercury speciation in solids using a thermal desorption technique.Fuel 160,525-530.
Rungnim,C.,Promarak,V.,Hannongbua,S.,Kungwan,N.,Namuangruk,S.,2016.Complete reaction mechanisms of mercury oxidation on halogenated activated carbon.J.Hazard.Mater.310,253-260.
Rupp,E.C.,Wilcox,J.,2014.Mercury chemistry of brominated activated carbons-Packed-bed breakthrough experiments.Fuel 117,351-353.
Sano,A.,Takaoka,M.,Shiota,K.,2017.Vapor-phase elemental mercury adsorption by activated carbon co-impregnated with sulfur and chlorine.Chem.Eng.J.315,598-607.
Sasmaz,E.,Kirchofer,A.,Jew,A.D.,Saha,A.,Abram,D.,Jaramillo,T.F.,et al.,2012.Mercury chemistry on brominated activated carbon.Fuel 99,188-196.
Senior,C.,Denison,M.,Bockelie,M.,Sarofim,A.,Siperstein,J.,He,Q.,2010.Modeling of thermal desorption of Hg from activated carbon.Fuel Process.Technol.91,1282-1287.
Sjostrom,S.,Dillon,M.,Donnelly,B.,Bustard,J.,Filippelli,G.,Glesmann,R.,et al.,2009.Influence of SO3on mercury removal with activated carbon:Full-scale results.Fuel Process.Technol.90,1419-1423.
Sun,P.,Zhang,B.,Zeng,X.,Luo,G.,Li,X.,Yao,H.,et al.,2017.Deep study on effects of activated carbon's oxygen functional groups for elemental mercury adsorption using temperature programmed desorption method.Fuel 200,100-106.
Tan,Z.,Xiang,J.,Su,S.,Zeng,H.,Zhou,C.,Sun,L.,et al.,2012.Enhanced capture of elemental mercury by bamboo-based sorbents.J.Hazard.Mater.239-240,160-166.
U.S.EPA(United States Environmental Protection Agency),2011.Mercury and Air Toxics Standards(MATS).Available:.https://www.epa.gov/mats,Accessed date:30 April 2018.
Vainio,E.,Fleig,D.,Brink,A.,Andersson,K.,Johnsson,F.,Hupa,M.,2013.Experimental evaluation and field application of a salt method for SO3 measurement in flue gases.Energy Fuel 27,2767-2775.
Yan,R.,Ng,Y.L.,Liang,D.T.,Lim,C.S.,Tay,J.H.,2003.Bench-scale experimental study on the effect of flue gas composition on mercury removal by activated carbon adsorption.Energy Fuel17,1528-1535.
Zhou,Q.,Duan,Y.,Chen,M.,Liu,M.,Lu,P.,2017.Studies on mercury adsorption species and equilibrium on activated carbon surface.Energy Fuel 31,14211-14218.
Zhu,C.,Duan,Y.,Wu,C.-Y.,Zhou,Q.,She,M.,Yao,T.,et al.,2016.Mercury removal and synergistic capture of SO2/NO by ammonium halides modified rice husk char.Fuel 172,160-169.