CONTROL OF SULFUR DIOXIDE AND SULFUR TRIOXIDE USING MAGNESIUM-ENHANCED LIME Joseph Potts and Erich Loch Cinergy Corporation Lewis Benson, Robert Roden and Kevin Smith Carmeuse North America

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime Overview Of Talk Background on control of SO 3 with Mg(OH) 2 and Ca(OH) 2 Magnesium-enhanced lime FGD process with byproduct Mg(OH) 2 Results of 800 MW and 1300 MW demonstrations of SO 3 control with byproduct Mg(OH) 2 Description of 1300 MW byproduct Mg(OH) 2 and SO 3 control system SO 3 control costs – byproduct Mg(OH) 2 vs. commercial Mg(OH) 2

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime SO 3 Emission from Coal-fired Plants From oxidation of SO 2 in furnace and SCR  Up to 3% oxidation, 70 ppmv SO 3 Can foul heat transfer surfaces Can cause visible plume TRI substance

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime Background on SO 3 control with Mg(OH) 2 Furnace injection of magnesium hydroxide to control SO 3  Reacts selectively with SO 3 to form water- soluble MgSO 4, but not with SO 2  Decades of experience in oil-fired units  Some use in coal-fired units  Increases melting point of slag

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime Magnesium-Enhanced Lime FGD Process Description Wet FGD process (Thiosorbic ® process) Uses lime reagent with 3-6 wt.% MgO, balance CaO Mg increases SO 2 removal and allows low L/G  21 L/G (3 l/Nm 3 ) for 91% removal with 4% sulfur coal Low chemical scaling potential  Liquid in absorber only 10% gypsum-saturated Lime is source of Mg for byproduct Mg(OH) 2

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime 800 MW and 1300 MW Demonstrations of Furnace Injection of Mg(OH) 2 DOE/NETL program by URS co-sponsored by EPRI, First Energy, AEP, TVA, and Carmeuse Objectives  90% SO 3 removal  Reduce plume opacity  Study balance-of-plant effects on: ­Slag accumulation ­SCR catalyst ­ESP ­Fly ash composition

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime Mg(OH) 2 Injection Locations Furnace Selective Catalytic Reduction ESP Wet FGD

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime 800 MW and 1300 MW Demonstrations of Furnace Injection of Mg(OH) MW unit  AH, ESP (100 SCA), magnesium-enhanced lime wet FGD  Baseline SO ppmv at ESP outlet 1300 MW unit  SCR, AH, ESP (400 SCA), magnesium-enhanced lime wet FGD  Baseline SO 3 37 ppmv at economizer outlet, 65 ppmv at SCR outlet

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime SO 3 Removal in 800 MW Furnace

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime SO 3 Removal in 1300 MW Furnace

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime SO 3 Removal Across 1300 MW Furnace and SCR

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime 800 MW and 1300 MW Demonstrations of Furnace Injection of Mg(OH) 2 No adverse impact on SCR catalyst or slagging ESP impact  800 MW – adverse when SO 3 reduced to 3-4 ppmv  1300 MW - no adverse impact ­Opacity monitor readings reduced from 16-20% to % Byproduct and commercial Mg(OH) 2 gave similar results

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime 800 MW and 1300 MW Demonstrations of Furnace Injection of Mg(OH) 2 Visible opacity significantly reduced Flyash composition within spec for sulfate

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime Hydrated Lime [Ca(OH) 2 ] Injection for SO 3 Control 12 micron avg. particle size, 16 m 2 /gram Demonstrated at 1300 MW for control of SO 3 following SCR  Injected after air heater Demonstrated at 1300 MW (Zimmer station) with post-SCR SO 3 concentrations  Injected after ESP  Captured in FGD absorber and completely utilized

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime

Magnesium-Enhanced FGD Process with Byproduct Mg(OH) 2

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime Byproduct Mg(OH) 2 System at Zimmer MgSO 4 + Ca(OH) 2 + 2H 2 O → CaSO 4 2H 2 O (gypsum) + Mg(OH) 2

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime Babcock & Wilcox design 54 ft (16.5 m) high straight shell L/G is 21 gal/1000 acfm (3 l/m 3 ) for 91% SO 2 removal Magnesium- Enhanced Lime Absorber at Zimmer Station

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime Ex-Situ Oxidizer at Zimmer Station

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime Byproduct Mg(OH) 2 from Magnesium- Enhanced Lime Wet FGD Process Byproduct process developed by Carmeuse Piloted in 1995 at Cinergy’s Zimmer station with support of EPRI, Ohio Coal Development Office and Cinergy Two plants currently producing byproduct Mg(OH) 2 Pre-treats FGD wastewater  Reduces dissolved solids by 80%, metals

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime Composition of Byproduct Mg(OH) 2

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime 1300 MW SO 3 Control System Design Parameters at Zimmer Station Mg(OH) 2 injection system design  3 TPH Mg(OH) 2  Mg:SO 3 ratio = 8  90% removal of furnace-generated SO 3 Ca(OH) 2 injection system  4 TPH Ca(OH) 2  Ca:SO 3 ratio 7.7  90% removal of SO 3 post-SCR

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime SO 3 Control Costs with Mg(OH) 2 Study by Carmeuse of 1300 MW byproduct Mg(OH) 2 system  $5.4 million capital cost  O&M cost $67/ton Mg(OH) 2  Compares with commercial Mg(OH) 2 cost of ~$210/ton  $2.5 million/yr savings  2 year payback  Wastewater pre-treatment at low cost

Control of SO 2 and SO 3 Using Magnesium-enhanced Lime Conclusions Injection of byproduct Mg(OH) 2 demonstrated at 800 and 1300 MW for 90% capture of furnace-generated SO 3 Byproduct Mg(OH) 2 system being installed in 1300 MW plant, start-up 1 st quarter 2004 Byproduct process pre-treats FGD wastewater Byproduct Mg(OH) 2 cost compares favorably with cost of commercial Mg(OH) 2 Hydrated lime controls SO 3 formed during SCR