77 West 200 South, Suite 210Salt Lake City, Utah 84101REACTIONENGINEERINGINTERNATIONALTutorial:Tutorial:Mercury Chemistry in BoilersMercury Chemistry in BoilersandMercury Control Technology (Part 1)Mercury Control Technology (Part 1)Presented byConnie Senior (senior@reaction-eng.com)April 17-21, 200530thInternational Technical Conference onCoal Utilization & Fuel SystemsClearwater, FloridaREACTIONENGINEERINGINTERNATIONALCourse Objectives•Mercury comes into the boiler in the coal•Sometimes mercury can be removed from the coal—butnot always•Mercury comes in different “flavors” (species) in flue gas•Mercury speciation in flue gas is not “magic”•The “flavor” of mercury in the flue gas affects how muchmercury is removed before the stack•Existing air pollution control devices remove some of themercury from flue gas•Mercury control technologies have been usedcommercially on incinerators, but not on electric utilityboilers•The most mature technology (demonstrated for longerthan six months) is activated carbon injection with abaghouseREACTIONENGINEERINGINTERNATIONALMercury Inputs to the Boiler0%20%40%60%80%100%0 0.1 0.2 0.3 0.4 0.5Hg content, ug/g

%Less than valuePetcokeTiresSubbituminousBituminousLignite• Highermedian valueforbituminous,lignites• BroaddistributionICR Part II data for 4thquarter 1999 were taken fromthis site and analyzed:http://utility.rti.org/part2/summaryP2.cfmREACTIONENGINEERINGINTERNATIONALhttp://ugs.utah.gov/emp/mercury/index.htmREACTIONENGINEERINGINTERNATIONALCan Hg in Coal Be Predicted?• Data from ICR Part II• Example: Coal datafrom two Marylandcounties, identified byseam• Hg vs. ash content• Trends within a seam,but cannot begeneralized too far!0.00.10.20.30.40.50 5 10 15 20 25 30Ash, wt% dry

Mercury, ug/g dryAllegheny (Pittsburgh)Allegheny (Tyson)Allegheny (various)Garrett (Mahoning)Garrett (Upper Freeport)Garrett (various)REACTIONENGINEERINGINTERNATIONALCan Hg in Coal Be Predicted?• Data from ICR Part II• Example: Coal datafrom two Ohiocounties, identified byseam• Hg vs. sulfur content• Trends within a seam,but cannot begeneralized too far!0.00.10.20.301234Sulfur content, wt% dry

Mercury content, ug/g dryHopkins - Kentucky #11Hopkins - Kentucky #4Knott - Elkhorn #3Knott - Hazard #4REACTIONENGINEERINGINTERNATIONALCan Mercury Be Removed?• Bituminous coals:– On a limited basis, mercury content follows trendsin sulfur or ash –no general relationship– Coal washing may reduce mercury from somecoal sources – limited applicationREACTIONENGINEERINGINTERNATIONALCan Mercury Be Removed?• Subbituminous coals:– Mercury organically bound in coal– Mild heating (e.g., K-Fuelprocess, WRI process)removes some mercury– Cost?Source: Bland et al., 2005REACTIONENGINEERINGINTERNATIONALHow Does Mercury Get into the Air?It starts with the fuel...FuelBottom AshBottom AshFly AshFly AshFGD Byproducts andFGD Byproducts andWasteStackEmissionsEmissions...but doesn’t all get to the stack...but doesn’t all get to the stackREACTIONENGINEERINGINTERNATIONALWhat Do We Mean by Speciation?• Gas-phase mercury:– Elemental: Hg0– Oxidized: Hg+2(HgCl2, other species?)• Particulate mercury– Hgp– Mercury (adsorbed on particles)REACTIONENGINEERINGINTERNATIONALWhy Do We Care About Speciation?-50%-25%0%25%50%75%100%125%150%10 100 1,000 10,000Coal Chlorine, ppm dry

Hg RemovalElementalOxidizedWet scrubbersremove:~90% of Hg+2<25% of Hg0=> Speciationin flue gasaffects capturein controldevicesSource: ICR dataREACTIONENGINEERINGINTERNATIONALMercury Chemistry in Flue GasHgCl2Gas-phasereactionsreactionsHeterogeneousreactionsHgpHgHg0AdsorptionAdsorptionOxidationOxidationREACTIONENGINEERINGINTERNATIONALMercury Speciation in CombustionSystems• Speciation at inletto air pollutioncontrol equipmentdepends on coaland ashcompositionFraction of particulate mercury in flue gasat inlet to particulate control device.(Source: ICR data)0%20%40%60%80%100%10 100 1,000 10,000Coal Chlorine, ppm dry

% as Hg p at InletREACTIONENGINEERINGINTERNATIONALhttp://ugs.utah.gov/emp/mercury/index.htmREACTIONENGINEERINGINTERNATIONAL-20%0%20%40%60%80%100%ESP Baghouse SprayDryerBaghouseWetScrubber

Mercury RemovalBituminousSubbituminousLigniteMercury Captured by Air PollutionControl EquipmentSource: EPA ICR DataREACTIONENGINEERINGINTERNATIONALMercury Captured by Air PollutionControl EquipmentBoilerBurnersAirHeaterFuelCoa l P ulveriza tion Coal SupplyP articulate CollectorS O2ScrubberStackSCRBoilerBurnersAirHeaterFuelCoa l P ulveriza tion Coal SupplyP articulate CollectorS O2ScrubberStackSCR...a walk through the boilerREACTIONENGINEERINGINTERNATIONALOxidation Across Full-Scale SCRs• Full-scale data• Large variation inobserved oxidation• Low oxidation withPRB (low chlorinecoal)0%20%40%60%80%100%0 500 1000 1500 2000Coal chlorine, ug/g

Oxidation of Hg

0 Across SCRNH3 OnNH3 OffREACTIONENGINEERINGINTERNATIONALOxidation of Hg Across APHs0%20%40%60%80%100%0 200 400 600 800 1000 1200 1400 1600Coal Chlorine, ug/g

Change in Hg

0 across APHNo SCR (low S)No SCR (med/high S)SCR (low S)SCR (med/High S)• Full-scale Hgspeciationmeasurements• Significantoxidation acrossAir Preheater• More data neededto understandbehaviorREACTIONENGINEERINGINTERNATIONALHg Removal in PCDsFrom ICR data:• High level of Hg removalpossible in FFs• ESPs have lowerremoval• Hot-side ESPs lowestremoval of Hg0%20%40%60%80%100%10 100 1,000 10,000Coal Chlorine, ppm dry

% Removal of HgFFCESPHESPREACTIONENGINEERINGINTERNATIONALRemoval of Total Hg Across ESPs• Data from plantsburning bituminouscoal• Carbon fromunburned carbon• Limited coal types indataset, butsurprisingly goodcorrelation withcarbon in ash0%20%40%60%80%100%0% 10% 20% 30% 40% 50%LOI %

%Hg Removal Across ESPDe Vito, et al.Sjostrom et al.Plant CPlant DPlant EFit to PC/CESP dataHot-side ESPStokerCycloneSource: Senior and Johnson, 2005REACTIONENGINEERINGINTERNATIONALActivated Carbon v. Fly Ash Carbon• Activatedcarbon:Highercapacity andreactivity thanfly ash carbon(per gram)0%20%40%60%80%100%0% 10% 20% 30% 40% 50%LOI %

%Hg Removal Across ESPDe Vito, et al.Sjostrom et al.Plant CPlant DPlant EFit to PC/CESP dataACIHot-side ESPStokerCycloneSource: Senior and Johnson, 2005REACTIONENGINEERINGINTERNATIONALMercury Removal in Dry Scrubbers• Spraydryer/fabricfilters effectivefor highchlorine (>500ug/g), but notfor lowerchlorine coalsSource: ICR dataICR SDA/FF Data-20%0%20%40%60%80%100%10 100 1000 10000Coal Cl, ug/g dry

Removal of Hg across SDA/FFBituminousLigniteSubbituminousREACTIONENGINEERINGINTERNATIONALMercury Removal in Dry Scrubbers• Spraydryer/fabricfilters effectivefor highchlorine (>500ug/g), but notfor lowerchlorine coals• Fabric filtersalone moreeffective forsubbituminouscoalsSource: ICR dataICR FF Data with and without SDA-40%-20%0%20%40%60%80%100%10 100 1000 10000Coal Cl, ug/g dry

Removal of HgBituminousLigniteSubbituminous(Open symbols are FF only)REACTIONENGINEERINGINTERNATIONALMercury Removal in Wet ScrubbersSource: ICR dataICR ESP/FGD Data0%20%40%60%80%100%10 100 1,000 10,000Coal Cl, ug/g dry

Removal of Hg across ESP/FGDBituminousLigniteSubbituminous• Speciation at inlet toFGD critical to highremoval acrossscrubber• Strategies forincreasing Hg+2atFGD inlet to bediscussed laterREACTIONENGINEERINGINTERNATIONALBehavior in Existing APCDs: Summary• Vapor-phase species:– Elemental: difficult to remove from gas– Oxidized: soluble in wet scrubbers, adsorbedmore readily by some sorbents• Hg found in vapor-phase and bound to particulatematter; partitioning depends on– carbon content– particulate control device (ESP vs. FF)– NOxcontrol (post-combustion, SCR)– coal type (bituminous vs. low rank)•Significant removal of Hg possible in existingAPCDsREACTIONENGINEERINGINTERNATIONALMercury in Byproducts• Mercury is already removed by– Fly ash– Scrubber sludge (FGDs)• Where does it go?REACTIONENGINEERINGINTERNATIONALUse of Fly Ash from Coal CombustionEstimates for 1999Source: Kilgroe, et al., 2001Fate Millionsof tons% Potential release mechanismsLand disposal 42.210 67.0% Leaching, windblown dustConcrete/grout 10.000 15.9% Leaching, volatilization(application-specific)Structural fills 3.200 5.1% UnlikelyWastestabilization 1.9003.0% UnlikelyMiningapplications1.500 2.4% LeachingRaw feed forcement kiln1.300 2.1% Volatilization in the kiln, withrecovery in finesRoadbase/subbase1.200 1.9% Not expected to be significantFlowable fill 0.850 1.3% UnlikelyOther 0.840 1.3%Total 63.000REACTIONENGINEERINGINTERNATIONALLeaching of Hg from Fly Ash• Results to date show little Hg leaches from fly ash instandard testsSource: Senior, et al., 2004Hg in (μg/L)TCLP SGLPSalem S.American bituminous 0.034 < 0.010Brayton Eastern bituminous < 0.010 0.01Brayton Eastern bituminous 0.02 0.05Brayton Eastern bituminous 0.02 0.02CoalPlantREACTIONENGINEERINGINTERNATIONALDistribution of Hg in FGD Plants• Most Hg in scrubberends up in FGDbyproduct, but notalways• Other testsconducted– Simulated gypsumcalcining at 300,350oF– TCLP of byproduct– Low T (125, 140oF)volatilization of Casulfite• Results: little Hgremoved from solidsSource: Richardson, et al., 2003020406080100120140 Bit / L S F Bit/ L S F Bit/LSF B i t/LSI

B i t / L S N Bi t / LF PRB/ LSF T X L ig/LSF TX L ig / L S I

%Hg in CoalFines LiquorGypsum FinesFGD ByproductFly AshLSF = Limestone Forced OxidationLS = Lime Forced OxidationLSI - Limestone Inhibited OxidationLSN = Limestone Natural OxidationREACTIONENGINEERINGINTERNATIONALMercury Control TechnologySource: Offen, et al., 2005Stage Process1. Laboratory Novel sorbents2. Pilot scaleNovel sorbents, oxidation catalysts,boiler and SCR Hg chemistry3. Full scale: capabilities/limitsCombustion mods, non-carbonsorbents, chemical additives,TOXECONTMII4. Full scale: multiple sitesACI, Chemically treated carbon,SCR/FGD5. Long term: 12-18 months TOXECONTM6. Widespread implementation---REACTIONENGINEERINGINTERNATIONALActivated Carbon Injection (ACI)DemonstrationsSource: US EPA, 2005APCConfiguration Bituminous Subbituminous LigniteC-ESPHudson* Pleasant Prairie 2 Leland Olds 1Brayton Point 1 Powerton* Coal CreekSalem Harbor 1 St. Clair 1Stanton 1Yates 1,2 MeramecPoplar River 1,2Valley* Miller*LauscheMonroeMiami Fort IndependenceAllenConesvilleH-ESPCliffside none noneFFnoneComanche 2* SprucePleasant Prairie*Presque IsleSDA/FFnoneHolcomb Stanton 10Antelope Valley 1SDA/ESPLaramie River 3PSnone Laskin 2 none*Pilot-scaleItalics denote testing that has not been completed (March, 2005)REACTIONENGINEERINGINTERNATIONALACI – Required EquipmentSource: Sjostrom et al., 2005SorbentStorageHg MonitorSorbentInjectionInjectionLancesREACTIONENGINEERINGINTERNATIONALDarco Hg Sorbent*• Lignite-derivedactivated carbon• 600 m2/g surfacearea• MMD 18 microns0%5%10%15%20%25%30%35%40%2.0 2.9 5.0 10.0 18.6 44.0 55.5 60.9 74.0Average size in bin, microns

Mass in bin*Formerly called DARCO FGDREACTIONENGINEERINGINTERNATIONALACI with ESPSource: ADA ESSorbentInjectionAsh andSorbentESPAsh andSorbentESPREACTIONENGINEERINGINTERNATIONALACI in ESP:Sorbent Injection at Pleasant PrairieSpray CoolingCarbon InjectionMercury AnalyzerMercury AnalyzerESP 2-4ESP 1-2Spray CoolingCarbon InjectionMercury AnalyzerMercury AnalyzerESP 2-4ESP 1-2REACTIONENGINEERINGINTERNATIONALInjectors, Geometry and GridSource: Cremer, et al., 2005REACTIONENGINEERINGINTERNATIONALEffect of Mixing on Hg0Removal• CFD Simulation ofSorbent trajectories andHg removal• Distribution of Hg0ingas• 10 lb/MMacf sorbentinjection• One-third of removaloccurs at 90oturn⇒high turbulence⇒good mixingHg0removal 32.6%Hg0removal 29.2%Hg0removal 26.5%Hg0removal 10.9%Hg0removal 32.6%Hg0removal 29.2%Hg0removal 26.5%Hg0removal 10.9%Source: Cremer, et al., 2005REACTIONENGINEERINGINTERNATIONALSummary of ACI Demonstrations:DARCO Hg & Plants with ESPsSource: Sjostrom et al., 2005Cold-Side ESP Units0204060801000 5 10 15 20 25ACI Rate, lb/MMacf

%Hg RemovalSt. ClairMeramecPleasant PrairieCoal CreekStantonLeland OldsBrayton PointREACTIONENGINEERINGINTERNATIONALSummary of ACI Demonstrations:DARCO Hg & Plants with SDA/FF0%20%40%60%80%100%02468ACI Rate, lb/MMacf

% Hg RemovalHolcomb (PRB)Stanton (Lignite)Source: Sjostrom et al., 2005REACTIONENGINEERINGINTERNATIONALEPRI TOXECONTMSorbentInjection~1% Ash andSorbentESPPJFFSorbentInjection~1% Ash andSorbentESPPJFFSource: ADA ESREACTIONENGINEERINGINTERNATIONALSummary of ACI Demonstrations:DARCO Hg & Plants with FFs• Gaston long-termdemonstration (12months) completed• Full-scaleTOXECONTMsystem underconstruction at WeEnergies PresqueIsleFF Units0204060801000 5 10 15 20 25ACI Rate, lb/MMacf

%Hg RemovalGastonSubbit (Pilot)Bit (Pilot)Range of ESP dataREACTIONENGINEERINGINTERNATIONALGeneral Trends in ACI:Single Sorbent (DARCO Hg)All Units0%20%40%60%80%100%0 5 10 15 20 25ACI Rate, lb/MMacf

% Hg RemovalESPSDA/FFFFREACTIONENGINEERINGINTERNATIONALLeaching of Hg from ACI +Fly Ash• Injection ofactivated carbonhas not shownincrease inmercury leachedfrom ash to dateSource: Senior, et al., 2004Hg in (μg/L)TCLP SGLPSalem S.American bituminous 0 0.034 < 0.010Salem S.American bituminous10< 0.010 < 0.010Salem S.American bituminous10< 0.010 < 0.010Brayton Eastern bituminous0< 0.010 0.01Brayton Eastern bituminous 0 0.02 0.05Brayton Eastern bituminous100.07 0.03Brayton Eastern bituminous0*0.03 0.01Brayton Eastern bituminous20< 0.010 0.01Brayton Eastern bituminous0*0.02 0.02Gaston COHPAC B-Side1.50.01 <0.01Gaston COHPAC B-Side1.5<0.01Gaston COHPAC B-Side1.5<0.01 <0.01Prairie PRB10<0.01 <0.01Prairie PRB10<0.01 <0.01Prairie PRB10<0.01*Old ESPPlant CoalInjectionRatelb/MacfREACTIONENGINEERINGINTERNATIONALACI+ESP Cost EstimatesSource: US EPA, 2005Estimated sorbent and disposal costs for injection upstream of a cold-side ESPCold-Side ESP Units0204060801000 0.5 1 1.5 2 2.5Sorbent and Sorbent Disposal Costs, mills/kWhr

%Hg RemovalBituminousSubbit/LigniteREACTIONENGINEERINGINTERNATIONALACI+FF Cost EstimatesSource: US EPA, 2005Estimated sorbent and disposal costs for injection upstream of a fabric filterFF Units0204060801000 0.5 1 1.5 2 2.5Sorbent and Sorbent Disposal Costs, mills/kWhr

%Hg RemovalBituminousSubbit/LigniteREACTIONENGINEERINGINTERNATIONALSummary•Mercury comes into the boiler in the coal•Sometimes mercury can be removed from the coal—butnot always•Mercury comes in different “flavors” (species) in flue gas•Mercury speciation in flue gas is not “magic”•The “flavor” of mercury in the flue gas affects how muchmercury is removed before the stack•Existing air pollution control devices remove some of themercury from flue gas•Mercury control technologies have been usedcommercially on incinerators, but not on electric utilityboilers•The most mature technology (demonstrated for longerthan six months) is activated carbon injection with abaghouseREACTIONENGINEERINGINTERNATIONALReferences• Alan Bland, Kumar Sellakumar, Lyle Johnson, Gary Walling, Duane Steen, and Edgar Klunder,“Mercury Control at Low Rank CoalFired Power Plants by a Pre-Combustion Thermal Treatment Process - An Update,” presented at 8th Annual Electric UtilitiesEnvironmental Conference, Tucson, AZ, January 24-26, 2005.• Cremer, M., Senior, C., Chiodo, A., Wang, D., Valentine, J., "CFDModeling of Activated Carbon Injection for Mercury Control inCoalFired Power Plants," presented at Electric Power Conference 2005, Chicago, IL, April 4-7, 2005.• Angela Jenkins and John M. Holloway III, “State Effortsto Get Ahead of the Feds inRegulating Emissions (CO2and Mercury),”presented at 8th Annual Electric Utilities Environmental Conference, Tucson, AZ, January 24-26, 2005.• Kilgroe, J.D., Sedman, C.B., Srivastava, R.K., Ryan, J.V., Lee, C.W., Thorneloe, S.A., 2001,Control of Mercury Emissions from CoalFired Electric Utility Boilers: Interim Report, U.S. Environmental Protection Agency, Office of Research and Development, NationalRisk Management Laboratory, Air Pollution Prevention and Control Division, EPA-600.R-01-109, December 2001.• George Offen, Ramsay Chang, Paul Chu and Richard Rhudy, “Mercury Control for Coal-fired Power Plants - An Update of TechnologyOptions,” presented at 8th Annual Electric Utilities Environmental Conference, Tucson, AZ, January 24-26, 2005.• Quick, J.C., Brill, T.C., and Tabet, D.E., Mercury in US coal – observations using the COALQUAL and ICR data sets,”EnvironmentalGeology2003,43, 247-259.• Richardson, M.K., Blythe, G.M., Golden,D., “Mercury Stability in FGD Byproducts”,presented at the DOE-EPRI-U.S. EPA -A&WMACombined Power Plant Air Pollutant Control Symposium - The Mega Symposium, Washington, DC, May 19-22, 2003.• Senior, C.L., Bustard, C.J., Durham, M.D., Baldrey, K., "Characterization of Fly Ash from Full-Scale Demonstration of Sorbent Injectionfor Mercury Control on Coal-Fired Power Plants,"Fuel Processing Technology2004,85, 601-612.• Senior, C.L., Johnson, S.A., “Impact of Carbon-in-Ash on MercuryRemoval across Particulate Control Devices in Coal-Fired PowerPlants,”Energy & Fuels2005,in press.• Sharon Sjostrom, Travis Starns, Jerry Amrhein, Jean Bustard,Wayne Penrod, Corey Lineville, Rich Phillips, Tom Hart, AndrewO'Palko, Ramsay Chang, “Full-Scale Evaluations of Mercury Control Technologies with PRB Coals,” presented at 8th Annual ElectricUtilities Environmental Conference,Tucson, AZ, January 24-26, 2005.• US EPA, “Control of Mercury Emissions from Coal Fired Electric Utility Boilers – An Update,” February 18, 2005,http://docket.epa.gov/edkpub/do/EDKStaffItemDetailView?objectId=090007d48068b4aa.