Use of Alkaline-Earth Hydroxides for Reduction of Plume Visibility in Coal-Fired Power Plants

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Use of Alkaline-Earth Hydroxides for Reduction of
Plume Visibility inCoal-Fired Power Plants

• Lewis Benson
• Carmeuse Technology

Mark Thomas Cinergy
Power-Gen International 2005 Las Vegas, Nevada
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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

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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 - lt 5 ppm SO3, 90 reduction
• Potential fit for alkali injection
• Demonstrated with SBS process
• New Power Plant
• lt 2 ppm SO3
• Wet ESP
• Alkali injection ahead of baghouse

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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.

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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
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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

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Full-scale Magnesium Hydroxide Injection
Applications

• Magnesium hydroxide
• Zimmer upper furnace - 20 mo. in service
• Fuel Chem TIFI / TDI furnace / air preheater

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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
• gt90 SO3 capture from 10-30 ppmv SO3
• 10 day continuous operation with lt240 F flue gas
  exit
• Carmeuse / Consol / Alstom / Allegheny Energy
  1.6 MW pilot
• SCR-like SO3 conc. 50 ppmv
• Demonstrate gt90 SO3 capture, air preheater
  cleanliness with lt240 F flue gas exit temperature
  for 3 month continuous operation

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Key Properties of Hydrated Limesfor SO3 Control
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Key Properties of Magnesium Compoundsfor SO3
Control
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Magnesium-enhanced Lime (Thiosorbic) Wet
FGDwith Byproduct Mg(OH)2 Production
for SO3 control
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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
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SO3 Removal in Furnace in 1300 MW NETL
Demonstration
Baseline SO3 37 ppmv at economizer outlet
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SO3 Removal Across 1300 MW Furnace and SCR in
NETL Demonstration
Baseline SO3 65 ppmv at SCR outlet
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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
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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

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Alkali Injection Short-term Performance Tests

• Hydrated lime pre-wet FGD
• 650 MW
• Hydrated lime pre-ESP
• Zimmer 1300 MW
• Gibson 5 - 625 MW

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SO3 Reduction w/ Mg(OH)2 and Hydrated Lime
Injection1300 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
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Effect of Specific Surface Area of Hydrated Lime
on SO3 Reduction1300 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
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Effect of Humidification on Hydrated Lime for SO3
Reduction625 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
1.1-1.3 30 23 3.5

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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

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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 lt5 ppm
• ESP performance with calcium or magnesium
  hydroxide depends on ESP design, improves with
  humidification

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Contact information

• Bob Roden Carmeuse FGT Technical Marketing
  Manager 412-777-0722 office 412-889-9662 cell
  bob.roden_at_carmeusena.com
• Lew Benson Carmeuse FGT Technical Manager
  412-777-0723 412-818-9839 or 412-225-8816 cell
  lew.benson_at_carmeusena.com
• Mark Thomas Cinergy 513-287-3802 office
  513-312-0124 cell mark.thomas_at_cinergy.com