Lewis Benson Carmeuse Technology Use of Alkaline-Earth Hydroxides for Reduction of Plume Visibility in Coal-Fired Power Plants Lewis Benson Carmeuse Technology Mark Thomas Cinergy Power-Gen International 2005 Las Vegas, Nevada

Overview Of Talk SO3 removal performance requirements Applicability of injection of alkaline earth compounds - hydrated lime, magnesium hydroxide Full-scale injection applications Results of full-scale demonstrations of SO3 control with calcium and magnesium hydroxides Tests of improved hydrated lime performance with higher surface area and humidification Balance-of-plant effects

Performance Requirements for SO3 Control and Applicable Technology Retrofit Return to pre-SCR SO3 in stack: ~50% reduction Good fit for alkali injection “Clear stack” - < ~5 ppm SO3, ~90% reduction Potential fit for alkali injection Demonstrated with SBS process New Power Plant < 2 ppm SO3 Wet ESP Alkali injection ahead of baghouse

Conditions Favoring Alkali Injection Existing FGD system with difficult retrofit for a WESP Existing FGD system with multiple absorber modules Little impact on sale of fly ash Problems with sulfuric acid corrosion in ductwork.

Compounds Tested for Injection for SO3 Control in Coal-fired Plants Sodium bisulfite Magnesium oxide Micronized limestone Ammonia Trona Soda ash Magnesium hydroxide Furnace Hydrated lime SCR dolomite, lime kiln dust, magnesite ESP Wet FGD

Full-Scale Calcium Hydroxide Injection Applications Hydrated lime – pre-ESP Zimmer – 1300 MW – 20 mo. in service Cumberland – 2 x 1300 MW – in engineering Hydrated lime – pre-wet FGD Widows Creek 8 - 550 MW – 1 yr in service 650 MW – 3 mo. in service

Full-scale Magnesium Hydroxide Injection Applications Zimmer – upper furnace - 20 mo. in service Fuel Chem TIFI / TDI – furnace / air preheater

Pilot-scale Magnesium Hydroxide Injection Testing NETL DOE / Consol / Alstom / Allegheny Energy - 1.6 MW pilot Injection ahead of Alstom pilot air preheater 4 moles Mg(OH)2 per mole SO3 inlet >90% SO3 capture from ~10-30 ppmv SO3 10 day continuous operation with <240 F flue gas exit Carmeuse / Consol / Alstom / Allegheny Energy – 1.6 MW pilot SCR-like SO3 conc. ~50 ppmv Demonstrate >90% SO3 capture, air preheater cleanliness with <240 F flue gas exit temperature for 3 month continuous operation

Key Properties of Hydrated Limes for SO3 Control

Key Properties of Magnesium Compounds for SO3 Control

Magnesium-enhanced Lime (Thiosorbic®) Wet FGD with Byproduct Mg(OH)2 Production for SO3 control

Injection Locations for Mg(OH)2 in NETL Demonstrations 37 ppmv SO3 at economizer outlet 65 ppmv SO3 at SCR outlet Commercial Mg(OH)2 or Byproduct Mg(OH)2

SO3 Removal in Furnace in 1300 MW NETL Demonstration Baseline SO3 37 ppmv at economizer outlet

SO3 Removal Across 1300 MW Furnace and SCR in NETL Demonstration Baseline SO3 65 ppmv at SCR outlet No adverse impact on SCR catalyst or slagging No significant adverse ESP impact Opacity monitor readings reduced from 16-20% to 10-15% Byproduct and commercial Mg(OH)2 gave similar results

Injection Locations for Mg(OH)2 and Ca(OH)2 for 1300 MW unit 1-3 TPH hydrated lime Furnace 50-75 gpm Mg(OH)2 slurry SCR ESP Wet FGD

Balance-of-Plant Issues with Mg(OH)2 and Hydrated Lime Injection in 1300 MW unit Furnace Magnesium salt deposit on economizer tubes ESP Mg(OH)2 no significant effect Hydrated lime No significant adverse effect at addition rate of 3 TPH No accumulation in ESP, downstream ducts Slight build-up at air in-leaks Flyash sales continue for concrete, other

Alkali Injection Short-term Performance Tests Hydrated lime – pre-wet FGD 650 MW Hydrated lime – pre-ESP Zimmer – 1300 MW Gibson 5 - 625 MW

SO3 Reduction w/ Mg(OH)2 and Hydrated Lime Injection 1300 MW, 3 TPH hydrated lime w/ 13 SSA, 75 gpm 15% commercial Mg(OH)2 slurry to furnace, SCR off Lime, TPH Stack SO3, ppmv 2 2.5 3 3.4

Effect of Specific Surface Area of Hydrated Lime on SO3 Reduction 1300 MW, 1.8 TPH hydrated lime, 50 gpm byproduct Mg(OH)2 slurry to furnace, SCR off SSA, m2/gram Stack SO3, ppmv No lime addition 15 13 12 21 6.5 23 4

Effect of Humidification on Hydrated Lime for SO3 Reduction 625 MW, 1 Effect of Humidification on Hydrated Lime for SO3 Reduction 625 MW, 1.8 TPH hydrated lime w/~23 SSA, pre-ESP, SCR off TPH lime gpm water SSA m2/gram Stack SO3 ppmv --- 15.6 1.1-1.3 23 5.7 30 3.5

Summary Injection of hydrated lime & magnesium hydroxide applicable for SO3 control Full-scale injection applications Options for hydrated lime injection location: pre-ESP, pre-FGD, pre-baghouse Options for magnesium hydroxide injection: upper furnace, post furnace Improved SO3 performance with higher surface area hydrated lime and humidification

Summary Furnace injection of Mg(OH)2 proven at 1300 MW for efficient capture of furnace-generated SO3; additional injection of hydrated lime ahead of ESP reduced stack SO3 <5 ppm ESP performance with calcium or magnesium hydroxide depends on ESP design, improves with humidification

Contact information: Bob Roden – Carmeuse FGT Technical Marketing Manager – 412-777-0722 office: 412-889-9662 cell; bob.roden@carmeusena.com Lew Benson – Carmeuse FGT Technical Manager – 412-777-0723; 412-818-9839 or 412-225-8816 cell; lew.benson@carmeusena.com Mark Thomas – Cinergy – 513-287-3802: office: 513-312-0124 cell; mark.thomas@cinergy.com