CONTROL OF SULFUR DIOXIDE AND SULFUR TRIOXIDE USING MAGNESIUM-ENHANCED LIMEJoseph Potts and Erich LochCinergy Corporation

Lewis Benson, Robert Roden and Kevin SmithCarmeuse North America

Control of SO2 and SO3 Using Magnesium-enhanced Lime

Overview Of Talk Background on control of SO3 with Mg(OH)2 and Ca(OH)2Magnesium-enhanced lime FGD process with byproduct Mg(OH)2 Results of 800 MW and 1300 MW demonstrations of SO3 control with byproduct Mg(OH)2Description of 1300 MW byproduct Mg(OH)2 and SO3 control systemSO3 control costs byproduct Mg(OH)2 vs. commercial Mg(OH)2

Control of SO2 and SO3 Using Magnesium-enhanced Lime

SO3 Emission from Coal-fired PlantsFrom oxidation of SO2 in furnace and SCRUp to 3% oxidation, 70 ppmv SO3 Can foul heat transfer surfacesCan cause visible plumeTRI substance

Control of SO2 and SO3 Using Magnesium-enhanced Lime

Background on SO3 control with Mg(OH)2Furnace injection of magnesium hydroxide to control SO3Reacts selectively with SO3 to form water-soluble MgSO4, but not with SO2Decades of experience in oil-fired unitsSome use in coal-fired unitsIncreases melting point of slag

Control of SO2 and SO3 Using Magnesium-enhanced Lime

Magnesium-Enhanced Lime FGD Process DescriptionWet FGD process (Thiosorbic process)Uses lime reagent with 3-6 wt.% MgO, balance CaOMg increases SO2 removal and allows low L/G21 L/G (3 l/Nm3) for 91% removal with 4% sulfur coalLow chemical scaling potentialLiquid in absorber only 10% gypsum-saturated Lime is source of Mg for byproduct Mg(OH)2

Control of SO2 and SO3 Using Magnesium-enhanced Lime

800 MW and 1300 MW Demonstrations of Furnace Injection of Mg(OH)2DOE/NETL program by URS co-sponsored by EPRI, First Energy, AEP, TVA, and CarmeuseObjectives90% SO3 removalReduce plume opacityStudy balance-of-plant effects on:Slag accumulationSCR catalystESPFly ash composition

Control of SO2 and SO3 Using Magnesium-enhanced Lime

Mg(OH)2 Injection LocationsMg(OH)2 Injection LocationsFurnaceSelective CatalyticReductionESPWetFGD

Control of SO2 and SO3 Using Magnesium-enhanced Lime

800 MW and 1300 MW Demonstrations of Furnace Injection of Mg(OH)2800 MW unitAH, ESP (100 SCA), magnesium-enhanced lime wet FGDBaseline SO3 32-39 ppmv at ESP outlet1300 MW unitSCR, AH, ESP (400 SCA), magnesium-enhanced lime wet FGDBaseline SO3 37 ppmv at economizer outlet, 65 ppmv at SCR outlet

Control of SO2 and SO3 Using Magnesium-enhanced Lime

SO3 Removal in 800 MW Furnace

Control of SO2 and SO3 Using Magnesium-enhanced Lime

SO3 Removal in 1300 MW Furnace

Control of SO2 and SO3 Using Magnesium-enhanced Lime

SO3 Removal Across 1300 MW Furnace and SCR

Control of SO2 and SO3 Using Magnesium-enhanced Lime

800 MW and 1300 MW Demonstrations of Furnace Injection of Mg(OH)2No adverse impact on SCR catalyst or slaggingESP impact800 MW adverse when SO3 reduced to 3-4 ppmv 1300 MW - no adverse impactOpacity monitor readings reduced from 16-20% to 10-15%Byproduct and commercial Mg(OH)2 gave similar results

Control of SO2 and SO3 Using Magnesium-enhanced Lime

800 MW and 1300 MW Demonstrations of Furnace Injection of Mg(OH)2Visible opacity significantly reducedFlyash composition within spec for sulfate

Control of SO2 and SO3 Using Magnesium-enhanced Lime

Hydrated Lime [Ca(OH)2] Injection for SO3 Control12 micron avg. particle size, 16 m2/gramDemonstrated at 1300 MW for control of SO3 following SCRInjected after air heaterDemonstrated at 1300 MW (Zimmer station) with post-SCR SO3 concentrationsInjected after ESPCaptured in FGD absorber and completely utilized

Control of SO2 and SO3 Using Magnesium-enhanced Lime

Control of SO2 and SO3 Using Magnesium-enhanced Lime

Magnesium-Enhanced FGD Processwith Byproduct Mg(OH)2

Control of SO2 and SO3 Using Magnesium-enhanced Lime

Byproduct Mg(OH)2 System at ZimmerMgSO4 + Ca(OH)2 + 2H2O CaSO42H2O (gypsum) + Mg(OH)2

Control of SO2 and SO3 Using Magnesium-enhanced Lime

Babcock & Wilcox design54 ft (16.5 m) high straight shellL/G is 21 gal/1000 acfm (3 l/m3) for 91% SO2 removalMagnesium-Enhanced Lime Absorberat Zimmer Station

Control of SO2 and SO3 Using Magnesium-enhanced Lime

Ex-Situ Oxidizer at Zimmer Station

Control of SO2 and SO3 Using Magnesium-enhanced Lime

Byproduct Mg(OH)2 from Magnesium-Enhanced Lime Wet FGD ProcessByproduct process developed by CarmeusePiloted in 1995 at Cinergys Zimmer station with support of EPRI, Ohio Coal Development Office and CinergyTwo plants currently producing byproduct Mg(OH)2Pre-treats FGD wastewaterReduces dissolved solids by 80%, metals

Control of SO2 and SO3 Using Magnesium-enhanced Lime

Composition of Byproduct Mg(OH)2

Mg(OH)2, wt. %

73

Gypsum, wt. %

21

Inerts, wt. %

6

Total Suspended Solids in slurry, %

20

BET Specific Surface Area, m2/g

55

Median Particle Size, microns

3

Control of SO2 and SO3 Using Magnesium-enhanced Lime

1300 MW SO3 Control System Design Parameters at Zimmer StationMg(OH)2 injection system design3 TPH Mg(OH)2Mg:SO3 ratio = 890% removal of furnace-generated SO3Ca(OH)2 injection system4 TPH Ca(OH)2Ca:SO3 ratio 7.790% removal of SO3 post-SCR

Control of SO2 and SO3 Using Magnesium-enhanced Lime

SO3 Control Costs with Mg(OH)2Study by Carmeuse of 1300 MW byproduct Mg(OH)2 system$5.4 million capital costO&M cost $67/ton Mg(OH)2Compares with commercial Mg(OH)2 cost of ~$210/ton$2.5 million/yr savings2 year paybackWastewater pre-treatment at low cost

Control of SO2 and SO3 Using Magnesium-enhanced Lime

ConclusionsInjection of byproduct Mg(OH)2 demonstrated at 800 and 1300 MW for 90% capture of furnace-generated SO3Byproduct Mg(OH)2 system being installed in 1300 MW plant, start-up 1st quarter 2004Byproduct process pre-treats FGD wastewaterByproduct Mg(OH)2 cost compares favorably with cost of commercial Mg(OH)2 Hydrated lime controls SO3 formed during SCR