Mirant: Who We AreINDEPENDENT POWER COMPANYMake and sell electricitycompetitively, reliably, ethically,and safely10 power plants in the USApproximately 10,000 MW ofgenerating capacity ~ 10 millionhomesCoal, natural gas, and oil fuelelectric generation fleetMidAtlantic’s generation output-sold to PJM wholesale electricitymarketMirant emplo s nearl 1 6001Mirant employs nearly 1,600employees in the U.S.Summary of Mid-Atlantic Air Pollution Control ProjectsInvesting for the Future: Air Quality Control Systems (>$1.6B)Flue Gas Desulphurization (aka FGD or Scrubbers)U 9 % l f SOf MD fl–Upto95%removalof SO2forMD fleet–Morgantown, Chalk Point and Dickerson Scrubbers placed in serviceDecember, 2009Selective Catalytic Reduction (SCR)–Up to 90% removal of NOx for MD fleet–Morgantown•Unit 1 placed in service June 2007•Unit 2 placed in service May 2008–Chalk Point•Unit 1 placed in service May2008–Dickerson•Selective Non-Catalytic Reduction (SNCR); Units 1, 2, 3 placed in serviceJ l 2009July 2009Together, FGDs and SCRs reduce ionic Hg by >80%SO2Control System at DickersonFlue Gas Desulphurization SystemO t f U it 1 2 d 3OnesystemforUnits1,2and 3‘Wet’ scrubber technologyRemoves ~ 95% of SOfrom Flue Gas2MDE regulations set annual tonnage limitsNearly 30,000 tons/year removed from the unitsCreates a Commercially Saleable By-ProductSO2reductions help the State of Maryland achieve compliance withthe National Ambient Air Quality Standard (NAAQS) for particulatematter smaller than 2 5 microns (PM 2 5)matter smaller than 2.5 microns (PM 2.5)Dickerson Generating StationThree coal-fired boilers,182 MW eachTwo Combustion Turbines (CTs),167 MW eachOne 13 MW Blackstart CTWater source: Potomac RiverE i i t l itEmissions controlunits:- Selective non-catalytic reduction (SNCR)- Electrostatic Precipitators- Baghouse- Flue Gas Desulfurization (FGD) SystemPurpose of FGD:To reduce the SO2, NOx, and Hg emissions of coal combustion viachemical reactions between water, flue gas, and limestone.Limestone arrives intrainsMixed with water tocreate slurryStack gases routedto absorber vessel• Clean flue gas• WastewaterGypsumWastewater (fromIWWTP) and river water•FGD Chemistry•SO2in flue gas reacts with water to create sulfurousacid (H2SO3)acid (H2SO3HSOreacts with the calcium carbonate (CaCO)2SO3reacts with the calcium carbonate (CaCO3)in limestone slurry to create calcium sulfite(CaSO) and liberatesCOas a gas &HOas a3),and liberatesCO2as a gas &H2Oas aliquid•O2is added by natural and forced oxidationCaSO3+ 1⁄2 O2combine to producegypsum(CaSO4)W t W t T t tFGDWasteWaterTreatmentFGDPhysical Chemical TreatmentMetals ReductionBiological TreatmentNitrogen Reduction7Physical Chemical SystemAlkali (pHcontrol)Organosulfide(metalsprecip.)FerricChloride(coagulant)PolymerHydrochloricTreatedWastewaterFGD PurgefromHydroclonesHydrochloricAcid(tobiologicaltreatmentorRecycle SludgeClarificationGravityFiltrationEqualizationDewateringSludgeorbackwash)RecycleSludgeFiltrationSludgegLandfillTankFiltrateCakeBackwash StreamBiological Treatment StagePerformed downstream of physical-chemicaltreatment, after removal of TSS andmetalsNitrogen removal–Activated Sludge reactors toremove N–Nitrogen levels of dischargeless than 4 ppmFGD Wastewater TreatmentPhysical Chemical SystemTreatment EffectivenessConstituent Typical Influent (mg/L) Typical Effluent (mg/L)TreatmentEffectivenessTSS 10,000 - 40,000 <30.0pH 4.5 - 6.0 6.5 - 8.5As 0.05 - 3.0 <0.05Cd0 04-0 5<0 10...Cr 0.3 - 5.0 <0.10Cu 0.1 - 0.85 <0.10Hg 0.05 - 0.8 <0.002Ni 0.2 - 6.0 <0.3Pb 0.1 - 3.0 <0.05Zn 0.4 - 8.0 <0.10Total N20-290<4.00TotalNNitrogen SourcesMakeup WaterRiver WaterRiverWaterSewage Treatment Plant EffluentIndustrial WWTP effluentFlue GasA i Sli f SCR/SNCR E i tAmmoniaSlipfromSCR/SNCREquipmentNitrous Oxide (NOx)95% NO and 5% NO2Nitrogen (N2)FGD System Nitrogen Containing Additives11FGDSystemNitrogenContainingAdditivesPolymers, DBA, etc