ICAC - U.S. EPA
December 3, 2015
Dr. Joe Wong, ADA Carbon Solutions
• Mercury control regulatory drivers
• Understanding & Applying the Science
– Fundamental Mechanisms – Contact, Conversion & Capture
– Applying the science of mercury capture in the plant
• Mercury control approaches
– Native Capture
– Sequestration Stability
– Mercury Re-emission
• Activated Carbon Injection as Best Available Control Technology
– Tuning Surfaces, Pores & Particles
– Advanced Carbon Innovations
• Compliance Planning
– Mercury Measurement
• Summary - Guiding Principles for mercury capture
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Institute of Clean Air Companies survey that covered 181 GW of coal-fired power
generation revealed:
MATS Update: Coal-Fired EGU Compliance Plans
Data based on late 2014 survey results. Source: Institute of Clean Air Companies; Power Magazine, April 2015
Activated Carbon Injection is viewed as Best Available Control Technology and
Maximum Achievable Control Technology
Number of Generating Units
Size of Generating Units, GW (%)
ACI 310 137 (76%)
Boiler Oxidant 49 26 (14%)
Non-carbon Sorbents 3 1.6 (1%)
Wet FGD Additives 36 16.5 (9%)
Totals 398 181 (100%)
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Industrial Boiler MACT
◦ Reconsideration of Final Rule
November 2015 (Not Yet
Published)
◦ Compliance: January 2016
◦ Major Source (>14,000 units)
> 10 TPY Single Pollutant or
> 25 TPY All Pollutants
◦ Mercury Emission for Existing
Sources: 5.7 lb/TBtu
◦ Typical Inlet Mercury
Concentrations: 4-12 lb/TBtu
Typical IB Boiler Utility Boiler
Size (Steam lb/hr)
100,000 3,500,000
Reliability > 95% ~75%
Use Various Steam ForTurbine
Boiler Temperature
Varies > 2,000°F
Flue Gas at PM Device
> 500 ° F < 350°F
NOx Control Simple (LNB, OFA, SNCR)
Advanced (LNB, OFA, SNCR,
SCR)
SOx Control Simple (DSI,SDA)
Advanced (DSI, SDA, WFGD)
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Cement MACT
◦ Final Amendments of Final
Rule July 2015 (Not Yet
Published)
◦ Compliance: September 2015
◦ Portland Cement Locations
(~100 plants)
◦ Some Cement Kilns Classified
ICI Boiler MACT
◦ Mercury Emission for Existing
Sources: 55 lb/Million Tons
Clinker
All Fuels Types
◦ Fuel Minor Source of Mercury
◦ Raw Materials Major Source of
Mercury
◦ All Particulate is Used in
Cement
◦ Process Raw Materials For
Cement
Boilers Generate Steam
◦ Flue Gas Temperatures Vary
Raw Mill On or Off
◦ Potentially Multiple PM
Devices
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• Industrial Boilers
– High temperature at injection point and in particulate collector
– High mercury content in coal in some cases
– Less likely to have SCR, wet scrubber in emissions train to enhance oxidation
– Lower cost for ACI equipment (about $0.5 to $1.2 Million vs $1 to 2 Million for utility-scale) driven by lower injection rates, smaller silos
• Cement Plants
– Recycle of mercury in process leads to higher concentrations
– Raw mill off condition can spike oxidized mercury flue gas emissions
– Variability in oxidation state/speciation of mercury still applies
– Removal of mercury from the system can be achieved by ACI into existing baghouse or scrubber
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Science of Efficient Mercury Capture
All three mechanisms must occur in seconds or less to achieve compliance.
Conversion
of elemental mercury (Hg0) to an oxidized
state (Hg+ or Hg++) to enhance mercury’s receptivity to the
capture mediaContactof mercury, which is in
very dilute concentrations in the
flue gas, with the capture media
Captureof the mercury in the
capture media’s structure for removal
from the system
Three Critical Mechanisms
Science of Efficient Mercury Capture
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MATS Implementation in US
Coal Pretreatment
Combustion Oxidation
Dry Sorbent Injection
SorbentInjection
Wet Scrubber Additives
• Integrate technology options and actively manage mercury control.
• Maximize native and co-benefit capture of mercury.
Post Scrubber Treatments
Applying Science in the Plant
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MATS Implementation in US Native Mercury Capture
• Can range from almost none to 90% of the coal mercury; may not
be consistent over time
• With extensive testing, some plants can rely on native control
alone for compliance
• Caveats
o Control is “passive” with no dial to turn up
o High degree of control is the exception rather than the rule
o May sub-optimize primary function of individual equipment
pieces
o Future changes to process conditions or coal may inhibit Hg
control
o Ash LOI is not a stable capture medium
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Activated carbon injection can be used in flue gas or
slurried into a scrubber
Scrubber additives include sulfides that precipitate
mercury
Removal from the system is also key; these solids
need to be separable
Good results have been reported with either PAC or
sulfides in scrubbers
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Mercury re-emissions from wet scrubbers is well documented
◦ Southern Company - EPRI/URS paper #57 from 2014 MEGA
describes oxidized Hg being reduced to elemental in the wet
scrubber and re-emitting
Stack Hg exceeds inlet Hg under changing process
conditions
Good example of Contact-Conversion-Capture not
succeeding
The same concept applies to other temporary capture
techniques
◦ Fly ash LOI is not a stable capture media; oxidation without
stable capture does not achieve compliance goals
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Creating Activated Carbon Features to Maximize Contact, Conversion & Capture
Tuning carbon surfaces, pores and particles improves Hg control properties
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Surfaces and Surface Area
Carbon surfaces can be tuned in different ways to maximize Hg capture
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Gen 2 “Innovation”
Step-change
Improvement in Hg
Capture EfficiencyGen 1 “Adaptation”
Traditional PAC Products
Adapted
for Mercury Removal
Gen 3+ “Collaborative
Specialization”
Resolving Specialized
Emission Requirements
• Concrete Compatible
• Acid/SO3 Tolerant
• DSI Compatible
• High Temperature
• Others
Rapid Innovation Will Continue to Enhance Activated Carbon Performance
GEN 1 PACs developed in the mid-2000s are no longer the industry performance
standard ... it’s new Gen 2 and Gen 3+ carbons
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0% 10% 20% 30% 40% 50% 60% 70%
A
B
C
D
E
% Hg Removal Relative to Baseline Removal
PAC
Fo
rmu
lati
on
Comparative Hg Removal Across ESP
Baseline PAC
Enhanced Oxidation/SO3 Tolerance #1
Enhanced Oxidation
SO3 Tolerance
Enhanced Oxidation/SO3 Tolerance #2
High sulfur fuel
blend, 18-24
ppm SO3
Stepwise
mechanistic
formulation
enhancement
s
GEN 3+ PACs have improved tremendously Hg removal efficiency in very demanding
flue gas conditions…thus, offering significantly lower costs of compliance.15
Initial MeasurementsUsing Appropriate
Methods
Evaluate Native/Co-Capture
Incorporate PlannedChanges to Operation
e.g. retrofits, fuel
Selected Tests; Confirmation
Measurements
Identify PotentialControl Approaches with Preliminary Cost Models
Evaluate CostsBalance-of-Plant
and Multi-Pollutant Interactions
Select, Procure, InstallTechnology and
CEMs or Trap Systems
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Sorbent Traps Mercury CEMS
Complexity Simpler More complex
Cost Lower Higher
Speciation in low-ash environments (neither is reliable in high-ash gas)
Under development Better established
Sample Transport In-situTransport to instrument
can pose challenges
Real-time data for process feedback
Not available Yes
Approved compliance method
PS 12B PS 12A + MATS App A
Insure that fundamental capture mechanisms of Conversion-Contact-
Capture are completed as effectively as possible and ideally all at once
Adopt true “engineering” or “active” control methods
◦ Take advantage of co-benefit capture from existing Air Pollution Control
operation, but be careful not to sub-optimize their primary function
Always consider balance of plant (BOP) issues... Avoiding corrosion, excess
bromine in water, scrubber re-emissions, Hg in water streams, Hg in solid
wastes, impact on other contaminants, need for added chemicals, etc.
Take advantage of new advanced Gen 2+ PACs that provide more cost-
effective compliance in specialized APC system requirements
Consider the stability of the mercury in the media of concern, avoid re-
emission
Testing is the only way to know for sure what your plant will do when
compliance levels are tight
Summary – Guiding Principles
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“Bid Specification and Information Requirements and Bid
Evaluation Form for Activated Carbon Injection Systems”
“Conducting a Successful Mercury Control Demonstration
Test at a Coal-Fired Power Boiler.”
“Improving Capture of Mercury Efficiency of WFDGs by
Reducing Mercury Reemissions”
ICAC MARAMA webinar, March 2013
Available at www.icac.com
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Contact:
Joe Wong
Chief Technology Officer
ADA Carbon Solutions, LLC
Littleton, CO
(303) 962-1967
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