Transcript NORIT ADA Sorbent Development meeting

Performance and Costs of
Mercury Control Technology
for Bituminous Coals
NC DAQ Mercury and CO2 Workshop
April 20, 2004
Raleigh, NC
Michael D. Durham, Ph.D., MBA
ADA-ES, Inc.
8100 SouthPark Way, Unit B
Littleton, CO 80120
(303) 734-1727
[email protected]
Outline
• Mercury Emissions from Coal Fired Boilers
• Background on Control Technology
• Sorbent Injection for Controlling Hg
Emissions
• Costs for Mercury Control
• Regulatory Parameters from a Control
Device Perspective
Hg Removal with Existing Equipment
Controls
PM Only
CS-ESP
HS-ESP
FF
PM Scrubber
Bituminous
Subbituminous
46%
12%
83%
14%
16%
13%
72%
0%
98%
38%
25%
Dry FGD
SDA + ESP
SDA + FF
Wet FGD
CS-ESP+Wet FGD
HS-ESP+Wet FGD
FF+Wet FGD
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81%
55%
96%
35%
33%
Existing Source MACT Limits
Subcategory
Hg
(lb/TBtu)1
Bituminous-fired
2.0
Subbituminous-fired
5.8
NOTE: Output-based standards are referenced to a baseline efficiency (35% for new units; 32% for existing units).
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Mercury Emissions with Average Capture for
Bituminous (46%) and Subbituminous (16%) Coals
Cumulative Distribution (%)
100
80
60
40
Other Bituminous
Subbituminous
20
0
0
5
10
15
Mercury in Coal (lb/TBtu)
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20
Options Available for Reducing
Mercury Emissions
1. Wet Flue Gas Desulfurization (FGD)
Scrubbers.
2. Sorbent Injection.
Novel approaches are not considered viable as
time from development to market is too long
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Control of Mercury in
Wet FGD Scrubbers
• Oxidized Mercury is water soluble and can
be captured in wet scrubbers.
– Some captured mercury gets re-emitted.
• Elemental mercury cannot be captured by
scrubbers.
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Mercury Removal in Wet Scrubbers for
Bituminous Coals
Mercury Removal (%)
100
80
60
40
Eastern Bit
Western Bit
20
Pittsburgh #8
0
0
500
1000
1500
2000
Coal Chloride (ppm)
Low correlation of existing data; difficult to
predict the mercury removal that will be
achieved in a WFGD
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Enhancing Capture of Hg in Wet Scrubbers:
Increase Amount of Oxidized Hg
Oxidizing
Catalysts
Wet Scrubber
SCR for
NOx
Electrostatic
Precipitator
Coal
Oxidizing
Chemicals
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Status of Technologies for
Oxidizing Mercury
• SCRs:
–
–
–
–
–
Documenting performance on full-scale installations.
Better performance on bituminous than subbituminous coals.
Possibility of aging effects.
Possibility of interferences from other chemicals.
Catalysts are being designed to reduce oxidation of SO3;
this may impact oxidation of Hg.
• Oxidizing Catalysts:
– Pilot-scale testing under way.
• Oxidizing Chemicals:
– Some very short-term full-scale tests.
– Concerns with corrosion.
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Sorbent Injection
Mercury Control
Technology
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Coal-Fired Boiler with Sorbent Injection
Sorbent
Injection
Hg
CEM
ESP or FF
Ash and
Sorbent
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Activated Carbon
Storage and Feed System
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Powdered Activated Carbon
Injection System
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ADA-ES Hg Control Program: Phase I
• Full-scale field testing of sorbent-based mercury
control on coal-fired boilers.
• Primary funding from DOE National Energy
Technology Laboratory (NETL).
• Cofunding provided by:
–
–
–
–
–
–
–
–
–
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Southern Company;
We Energies;
PG&E NEG;
EPRI;
Ontario Power Generation;
TVA;
FirstEnergy;
Kennecott Energy; and
Arch Coal.
Removal of Mercury Species with PAC
on Bituminous Coal
Bituminous with FF
PAC Injection
COHPAC™ Inlet
COHPAC™ Outlet
Removal Efficiency
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PARTICULATE
OXIDIZED
ELEMENTAL
TOTAL
μg/m3
0.23
0.12
45.6%
μg/m3
6.37
0.91
μg/m3
4.59
0.03
μg/m3
11.19
1.05
85.7%
99.3%
90.6%
Cost and Performance of
Sorbent-Based Mercury Control
100
Mercury Removal (%)
90
80
70
60
50
FF Bituminous
40
FF PRB (EPRI Pilot)
30
ESP Bituminous
20
ESP PRB
10
0
0.0
0.5
1.0
1.5
2.0
2.5
Sorbent Costs (mills/kWh)
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3.0
3.5
4.0
Effect of Flue Gas Characteristics
• The capacity of sorbents to capture
mercury decreases at higher temperatures.
• Chlorine and other trace acid gases play a
significant role in the performance of PAC.
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Adsorption Capacity vs. Temperature
Equilibrium Adsorption Capacity - Darco FGD
( g HgCl2 /g AC)
3000
2500
2000
1500
1000
500
0
200
250
300
350
Temperature (F)
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400
450
Hg Capture vs. Temperature (w/ACI)
100
90
Mercury Removal (%)
80
ESP Bitum 300F
ESP - Bitum 350F
70
60
50
40
30
20
10
0
0
5
10
15
20
Sorbent Injection Rate (lb/Macf)
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25
30
Equilibrium Adsorption Capacity (µg Hg/g AC)
Equilibrium Adsorption Capacities at 250°F
Upstream and Downstream of SO3 Injection
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10000
Upstream of
SO3
9000
8000
Downstream of
SO3
7000
6000
5000
4000
3000
2000
1000
0
FGD Carbon
Norit Insul Carbon
P4 Ash
PAC Performance with ESPs:
Effect of Trace Acid Gases
100
Mercury Removal (%)
90
80
70
60
50
40
ESP Low S Bit
30
ESP PRB
20
ESP Hi S Bit
10
0
0
5
10
15
20
Sorbent Injection Rate (lb/MMacf)
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25
30
Sorbent Injection
Upstream of a Wet Scrubber
• Injection of AC and capture in ESP will provide an
additional mechanism to reduce mercury emissions.
• Oxidation of mercury produced by carbon could
enhance capture in FGD.
• Decreased mercury levels in scrubber could reduce
potential for reemission of elemental mercury from
scrubber.
• Two DOE/Industry full-scale field tests are scheduled:
– Georgia Power Yates; currently on-going, medium-sulfur
bituminous coal; and
– AEP Conesville; Spring ’05, high-sulfur bituminous.
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Ash Issues
• The mercury captured by PAC, LOI, and ash appears
to be very stable and unlikely to reenter the
environment.
• The presence of PAC will most likely prevent the sale
of ash for use in concrete.
• Several developing technologies to address the
problem:
–
–
–
–
–
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Separation
Combustion
Chemical treatment
Non-carbon sorbents
Configuration solutions such as EPRI TOXECON™
TOXECON™ Configuration
TOXECON™
N
Sorbent
Injection
PJFF
Coal
Electrostatic
Precipitator
Fly Ash (99%)
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Fly Ash (1%) + PAC
Alabama Power E. C. Gaston Unit 3
• 270 MW firing a variety of lowsulfur, washed eastern
bituminous coals.
• Particulate Collection:
– Hot-side ESP;
SCA = 274 ft2/kacfm
– COHPAC™ baghouse
• Wet ash disposal to pond.
• Primary funding from DOE/NETL
with cofunding provided by:
–
–
–
–
–
–
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Southern Company
Duke Energy
Ontario Power Generation
TVA
Kennecott Energy
We Energies
– EPRI
– First Energy
– Hamon Research-Cottrell
– Arch Coal
% Hg Removal
Phase I Test Results
PRS4003
100
90
80
70
60
50
40
30
20
10
0
0
1
2
3
4
5
Injection Concentration (lbs/MMacf)
Year-Long TOXECONTM Test
• Conduct ~ 1 year demonstration of
TOXECONTM (sorbent injection into COHPAC)
for power plant mercury control.
• Determine design criteria and costs for new
TOXECONTM systems.
• Determine balance-of-plant impacts.
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Daily and Weekly Average Mercury
Hg (ug/cm)
30
20
15
10
5
Removal Efficiency (%)
0
7/18/03
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Inlet
Outlet
Inlet Weekly
Outlet Weekly
25
8/7/03
8/27/03
9/16/03
10/6/03
10/26/03
11/15/03
100
Daily
80
Weekly
60
40
20
0
7/18/03
8/7/03
8/27/03
9/16/03
10/6/03
10/26/03
11/15/03
Impact of Injection on Performance
4.5
Average p/b/h
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0
0.5
1
1.5
2
2.5
3
3.5
Injection Concentration (lbs/MMacf)
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4
% Hg Removal
Phase I Test Results
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100
90
80
70
60
50
40
30
20
10
0
0
1
2
3
4
5
Injection Concentration (lbs/MMacf)
Low Load/Low Flow Test
• Baseline conditions limit injection
concentration.
• Test plan changed to accommodate real-life
conditions.
• Current air-to-cloth ratio of 8.0 ft/min is too
high for TOXECONTM.
• Low load test conducted to simulate
operation at air-to-cloth ratio of 6.0 ft/min
– APC arranged for 72 hours of operation at low,
steady load.
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30
Outlet 3%
25
20
Inlet 3%
15
10
5
11/6/03
11/7/03
11/8/03
11/9/03
100
5.0
80
4.0
60
3.0
Switched Feeders
40
2.0
20
1.0
0
11/5/03
0.30
0.25
0.20
0.15
0.10
0.05
0.00
11/5/03
11/6/03
11/7/03
11/8/03
Boiler Load/1000
Frequency
Mass Loading
11/6/03
11/7/03
11/8/03
0.0
11/9/03
6
5
4
3
2
1
0
11/9/03
Inj Conc (lbs/MMacf)
0
11/5/03
Hg
Removal
Carbon
Pulses/bag/h
Loading (gr/acf)
Removal Efficiency (%)
Concentration (ug/cm)
Low Load Test: A/C = 6.0 ft/min
B Mass Loading
Boiler Load/1000
B Pulse Freq.
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ACI Cost Estimates for Bituminous Coals
• Assumptions
– 250 MW Plant; 80% Capacity Factor
• Capital and Operating Costs for ESP
– 50-70% Hg Removal: PAC Injection @ 10 lb/Macf
– PAC Injection Equipment:
$790,000
– Carbon costs:
$2,562,000/yr
• Capital and Operating Costs for FF
–
–
–
–
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Add COHPAC Fabric Filter at $50/kW: $12,500,000
80-90% Hg Removal: PAC Injection @ 3 lb/Macf
PAC Injection Equipment:
$790,000
Carbon costs:
$769,000/yr
• Costs of mercury
control are unrelated to
the amount of mercury
captured
– Sorbent Injection
Technology
– SCR/FGD
– Catalytic Oxidation
– Other Developing
Technologies
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Hg Control Costs ($/wt)
Costs of Mercury Control Depend on
Plant Size Not on Amount Removed
100
80
60
40
20
0
0
5
10
15
Mercury in Coal (Hg/TBTU)
20
Conclusions on ACI Performance
• AC injection can effectively capture elemental and oxidized
mercury from bituminous coals.
• There will be difference in site to site performance of ACI due
to differences in coal, equipment, and flue gas
characteristics.
• Fabric filters provide better contact between the sorbent and
mercury than ESPs, resulting in higher removal levels at
lower sorbent costs.
• Long-term results are promising showing consistent Hg
removal greater than 85%.
• New COHPAC™ fabric filters will have to be designed to
handle higher loadings of PAC to insure high (>90%) mercury
removal.
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Commercial Status of Technology
1. Equipment
•
•
•
•
Similar equipment has been used successfully in the waste
industry to inject AC into flue gas.
It has successfully been scaled up for full-scale utility
applications.
Operating continuously for nearly a year at Gaston.
Three AC injections systems currently operating.
2. Supply of Activated Carbon and Other Sorbents
•
•
•
Sufficient supply available to meet several State regulations.
Additional production needed to meet Federal regulations.
Tremendous progress being made with improved sorbents.
3. Performance
•
•
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Will vary with type of equipment (FF vs. ESP).
Will vary from site to site due to flue gas characteristics
(temperature, acid gases).
Availability of Activated Carbons
Current excess capacity
of AC production
in Tons/year
NORIT Americas:
Other US Suppliers:
Total US Excess Capacity
22,500
40,000
62,500
Donau (Germany)
CarboChem (China)
Total Import Excess Capacity
130,000
60,000
190,000
Total US and Import Excess Capacity
252,500
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Number of 250 MW Plants that Can Be Treated by
Currently Available AC (out of 1100 in US)
Excess Capacity
ESPs
Tons/yr
(50-70%)
FF
(70-90%)
US AC
62,000
30
99
Total US
Plus Imports
252,000
120
400
• Manufacturers plan to increase production to meet market
demand, but only upon regulatory certainty.
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Regulatory Parameters from a Control
Device Perspective
1. Long term averaging
2. Dual Limit
•
•
Removal Efficiency
Emission Limit
3. Flexibility in Achieving Mercury Removal
•
•
Accounts for site by site variation in performance
Enhances cost effectiveness
4. Mechanism to Encourage Adoption
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Long-Term Averaging Time will Allow Control Devices to
Adapt to Variations in Coal and Operating Conditions
Hg (µg/Nm3)
25
Ontario Hydro
20
Total Inlet
15
10
5
Total Outlet
0
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4/23
4/24
4/26
4/25
Load
Sorbent Injection Concentration
4/23
4/24
4/25
4/26
4/27
12
10
8
6
4
2
0
4/27
Inj. Conc. (lb/MMacf)
Boiler Load (MW)
4/22
300
250
200
150
100
50
0
4/22
Decisions on Mercury Control with
Flexibility in Achieving Reductions
Utilities would have a significant economic
incentive to put mercury control on units that are:
• Higher emitters
• Larger plants
Therefore, a flexible approach would result in the
greatest reduction in total mercury emissions
while minimizing costs
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Flexibility Would Provide a Framework for
Fleet-wide Decisions on Mercury Control
100
Mercury Removal (%)
90
80
70
60
50
FF Bitum
40
FF PRB
30
ESP Bituminous
20
ESP PRB
10
0
0.0
0.5
1.0
1.5
2.0
2.5
Sorbent Costs (mills/kWh)
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3.0
3.5
4.0
Flexibility Would Help Address Plant by
Plant Variations in Performance Guarantees
100
Mercury Removal (%)
90
ESP Bitum
80
ESP PRB
70
60
50
40
30
20
10
0
0
5
10
15
20
Sorbent Injection Rate (lb/Macf)
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25
30
Early Adoption of Technology
Provides Increased Experience Base
• To date, 8 full-scale field tests have been
completed through funding from DOE-NETL,
EPRI, Utilities, APC Vendors, and Coal
Companies.
• An additional 12 field tests are planned for the
next 2-3 years.
• Economic incentives for early compliance are
needed to offset risks with new technology.
• This will increase the operational data base
(different fuels and equipment), decrease
uncertainty, solidify guarantees.
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