1. 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

2. 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

3. 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

4. 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.

5. 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

6. 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 MW – 1 yr in service
650 MW – 3 mo. in service

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

8. Pilot-scale Magnesium Hydroxide Injection Testing
NETL DOE / Consol / Alstom / Allegheny Energy 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

9. Key Properties of Hydrated Limes for SO3 Control

10. Key Properties of Magnesium Compounds for SO3 Control

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

12. 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

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

14. 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

15. 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

16. 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

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

18. SO3 Reduction w/ Mg(OH)2 and Hydrated Lime Injection 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

19. Effect of Specific Surface Area of Hydrated Lime on SO3 Reduction 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

20. 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 23
5.7 30
3.5

21. 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

22. 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

23. Contact information:
Bob Roden – Carmeuse FGT Technical Marketing Manager – office: cell;
Lew Benson – Carmeuse FGT Technical Manager – ; or cell;
Mark Thomas – Cinergy – : office: cell;