Transcript Document

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
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•
•
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- 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
Control of SO3 Using Ca(OH)2 and Mg(OH)2
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
Control of SO3 Using Ca(OH)2 and Mg(OH)2
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.
Control of SO3 Using Ca(OH)2 and Mg(OH)2
Compounds Tested for Injection for SO3
Control in Coal-fired Plants
Magnesium oxide
Micronized limestone
Magnesium
hydroxide
dolomite, lime
kiln dust,
magnesite
Sodium
bisulfite
Furnace
SCR
Ammonia
Trona
Soda ash
Hydrated
lime
ESP
Control of SO3 Using Ca(OH)2 and Mg(OH)2
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
Control of SO3 Using Ca(OH)2 and Mg(OH)2
Full-scale Magnesium Hydroxide Injection
Applications
• Magnesium hydroxide
 Zimmer – upper furnace - 20 mo. in service
 Fuel Chem TIFI / TDI – furnace / air preheater
Control of SO3 Using Ca(OH)2 and Mg(OH)2
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
Control of SO3 Using Ca(OH)2 and Mg(OH)2
Key Properties of Hydrated Limes
for SO3 Control
Ca(OH)2, wt. %
Specific Surface
Area, m2/g
Average Particle
Size, microns
92 - 95
10 - 25
4 - 10
Control of SO3 Using Ca(OH)2 and Mg(OH)2
Key Properties of Magnesium Compounds
for SO3 Control
60
98
--12
Byproduct
Mg(OH)2
20
60-65
--55-75
3
3
Mg(OH)2
Solids, %
Mg(OH)2, wt. %
MgO, wt. %
Specific Surface
Area, m2/g
Average Particle
Size, microns
Control of SO3 Using Ca(OH)2 and Mg(OH)2
MgO
----97
40
5
Magnesium-enhanced Lime (Thiosorbic®) Wet FGD
with Byproduct Mg(OH)2 Production
Cleaned Gas
Magnesium
Enhanced
Absorber
Lime
Water
Flue
Gas
Slaker
Lime
Slurry
Tank
Oxidizer
Belt Filter
Inerts
Compressed
Air
Gypsum
Byproduct
Pre-Treated
FGD Effluent
Byproduct
Magnesium
Hydroxide Precipitation
Tank
System
pH 9.5 - 10
Gypsum
to Oxidizer
Control of SO3 Using Ca(OH)2 and Mg(OH)2
Magnesium
Hydroxide
for SO3 control
Injection Locations for Mg(OH)2 in NETL
Demonstrations
Commercial
Mg(OH)2
or
Byproduct
Mg(OH)2
37 ppmv SO3
at economizer
outlet
65 ppmv SO3
at SCR outlet
Control of SO3 Using Ca(OH)2 and Mg(OH)2
SO3 Removal in Furnace in 1300 MW
NETL Demonstration
Baseline SO3 37 ppmv at economizer outlet
100%
90%
SO3 Removal
80%
70%
60%
50%
40%
30%
20%
10%
0%
0
1
2
3
4
5
6
7
Mg:SO3 Molar Ratio based on economizer outlet SO3 concentration
Control of SO3 Using Ca(OH)2 and Mg(OH)2
8
SO3 Removal Across 1300 MW Furnace
and SCR in NETL Demonstration
SO3 Removal at ESP Outlet
100%
Baseline SO3 65 ppmv at SCR outlet
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
0
1
2
3
4
5
6
7
Mg:SO3 Molar Ratio (based on baseline SCR outlet SO3)
Control of SO3 Using Ca(OH)2 and Mg(OH)2
8
Injection Locations for Mg(OH)2 and
Ca(OH)2 for 1300 MW unit
50-75 gpm
Mg(OH)2
slurry
Furnace
SCR
1-3 TPH
hydrated
lime
ESP
Control of SO3 Using Ca(OH)2 and Mg(OH)2
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
Control of SO3 Using Ca(OH)2 and Mg(OH)2
Alkali Injection Short-term Performance
Tests
• Hydrated lime – pre-wet FGD
 650 MW
• Hydrated lime – pre-ESP
 Zimmer – 1300 MW
 Gibson 5 - 625 MW
Control of SO3 Using Ca(OH)2 and Mg(OH)2
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
Control of SO3 Using Ca(OH)2 and Mg(OH)2
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
Control of SO3 Using Ca(OH)2 and Mg(OH)2
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
1.1-1.3
30
23
3.5
Control of SO3 Using Ca(OH)2 and Mg(OH)2
Summary
• Injection of hydrated lime & magnesium
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•
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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
Control of SO3 Using Ca(OH)2 and Mg(OH)2
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
Control of SO3 Using Ca(OH)2 and Mg(OH)2
Contact information:
• Bob Roden – Carmeuse FGT Technical
Marketing Manager – 412-777-0722 office:
412-889-9662 cell;
[email protected]
• Lew Benson – Carmeuse FGT Technical
Manager – 412-777-0723; 412-818-9839 or
412-225-8816 cell;
[email protected]
• Mark Thomas – Cinergy – 513-287-3802:
office: 513-312-0124 cell;
[email protected]
Control of SO3 Using Ca(OH)2 and Mg(OH)2