mercury control in north america using powdered activated ... · for epri, doe, utilities • the...

Expertise. Reliability. Compliance.

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Mercury Controlin North America Using

Powdered Activated Carbon (PAC)

Mercury Emissions from Coal (MEC 12)2 March 2017

Sheila GlesmannADA Carbon Solutions, LLC


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Outline

• U.S. Compliance Trends

• Continued Optimization

• State of ADA Carbon Solutions’ PAC advancements

• Synergies of controls together

• Anticipating future needs for change

• Coal flexibility, load cycling

• Water and ash management - intersections with air

pollution control choices

• Conducting useful testing and demonstrations


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ADA Carbon Solutions, LLC

• ADA Carbon Solutions is committed to flue gas mercury control. We manufacture powdered activated carbons and continuously drive improvement through science using our in-house R & D and collaboration

• Headquartered in Littleton CO and operating three facilities in Louisiana

• Since 2008 have built significant market share in the North American mercury control market

• Personnel experience in coal-fired mercury measurement and control goes back to 1990’s technology development for EPRI, DOE, utilities

• The decades of power plant mercury control experience is invaluable for evaluating and applying technology efficiently


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• EPA’s AMPD (Air Markets Program Database) provides data on compliance technologies

• On Sep 30 (downloaded Feb 2017) 324 coal-fired units reported an hourly mercury emission value midday. About 220 of these have a mercury-specific technology listed.

• Activated Carbon Injection (ACI) is the BACT and MACT technology

• Over 70 GW documented by DOE’s Energy Information Agency from 2014-April 2016; understates magnitude

• Many coal-fired plants were already using ACI under state rules, permits, and consent decrees

• ICAC documented >135 GW (over 300 units) as of late 2014

• EPA’s AMPD shows over 200 units reporting ACI as part of strategy; database is incomplete

Mercury Control Applications under MATS


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• Additives

• In EPA’s AMPD there is no distinction between coal additives (e.g. halogens on coal) and/or scrubber additives (e.g. sulfides or PAC)

• All wet scrubber additives require oxidation of mercury upstream of scrubber, this can be accomplished through native halogens in coal or halide additives, and/or through SCR

• About 80 units list “additives” as part of strategy

• Other technologies include catalyst (10 units), non-PAC sorbents (2 units), sodium-based (4 units), regenerative activated carbon (1 unit); many list multiple technologies

AMPD-Reported Mercury Control under MATS


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PAC has been safely handled at industrial sites for decades in water treatment and in the past 20 years for flue gas injection.

To many utilities however, it is a new material. It is distinct from coal because our

manufacturing process drives off volatiles and moisture, making it less susceptible

to fire and explosion risk than pulverized coal. With knowledge of the proper

handling it can continue to be a safe part of the industrial work environment.

Some of the startup guidelines are connected to material handling safety.

Education on the Safety Data Sheet (SDS) of the material, Personnel Protective

Equipment (PPE) required, housekeeping/cleanup, and measurements available is

recommended. For more details on safe PAC handling, refer to our handouts,

product information and technical experts.

• Also ICAC White Paper is available on Safe Sorbent Handling

The Good News…

Safe PAC Material Handling


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Relative Performance, all units


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Relative Performance of Lignite Units


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Optimization Over Time

• We have come a long way since early 2000’s PAC injection rates

of 5-20 lb/MMacf and today, rates have dropped dramatically

• Plants have found ways to reduce sorbent use or do

intermittent injection through improved distribution and Co-

benefits

• Suppliers have advanced the technology to reduce sorbent

consumption and address more-challenging applications:

• SO3-tolerant PACs and/or DSI for SO3 management

• Higher temperature–compatible PACs

• Sodium reagent interferences addressed

• Reduction in PAC usage as shown in case studies


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Benefits of Optimization

• Load cycling operation in a competitive power price environment has driven a laser focus on costs

• Lowest cost of compliance is key to success

• Compliance has to consider air, water, solids utilization/storage

• Lower PAC injection rates through improved products and fine-tuning process controls/feedback have led to

• Continued utilization of ash; improved foam stability; good strength properties

• Less impact from halogens / oxidation

• Learning curve on ability to manage the chemistry

• Reinforcement of key principle of removing mercury all at once with minimal balance-of-plant effect

PAC is not the only cost


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PAC Innovations to Adapt to the Evolving Performance Landscape

GEN 1 PACs developed in the mid-2000s are no longer the industry performance standard ... it’s new Gen 4 and Gen 5 carbons

2000… …2010 2012 2014 2015+

Gen 1 “Adaptation”

• Power PACTM

• Power PAC PremiumTM

Traditional PAC Products Adapted

for Mercury Removal

Step-change Improvement in Hg Removal

Efficiency

Resolving Specialized Emission Requirements

Gen 3 “Collaborative Specialization”

• Concrete Compatible• Acid/SO3 Tolerant• Trona –Compatible• High-Temperature• Baghouse Optimized• WFGD Optimized

Gen 2 “Innovation”

• Power PAC Premium PlusTM

• FastPACTM

Platform

Gen 4 & 5+“Balance of Plant & Multi-contaminant

Specialization”

• Corrosion• Coal Combustion Residual

(solids) & Effluent Limitations Guidelines (liquid)impacts

• Fate of contaminants (Br, Hg, Se, As, etc.)

• By-product sales

Optimization & Holistic Solutions


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Active Engineering Controls withGeneration 2 PACs - 20122012

• > 200 MW EGU

• PRB coal fired

• Emission Configuration:

Econ-ACI-APH-ESP-Stack

• Hg CEMS

Gen 2 PACs can reduce carbon usage by 50% and Improved Hg Removal to >95%

Steep, Rapid Capture

Low Hg Residual& Secure Capture

GEN 2

FastPACTM Premium

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0.0 1.0 2.0 3.0 4.0 5.0

Emis

sio

n R

ate

(lb

/TB

tu)

Lbs Activated Carbon / MMacf

Gen 1

PowerPAC Premium™

Emission Standard 1.2 lb/TBtu-60%


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Developmental Work – Laboratory Results

• Our lab Dynamic Mercury Index (DMI) test provides rapid PAC Hg removal performance comparisons.

• Our patent-pending Gen 4 & 5 FastPAC series PACs have significantly enhanced Hg removal performance compared to standard Gen 1 PACs like PowerPAC Premium.


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Full-Scale Testing of Advanced Gen 4 FastPAC Platinum

Target Emission Rate

Gen 4FastPAC Platinum

~40% reduction in PAC Usage

Hg

Emis

sio

ns

ACI Rate

Gen 2FastPAC Premium

Our Gen 4 FastPAC Platinum reduced PAC usage by 38% compared to our Gen 2 FastPAC Premium in a sodium DSI system.

PRB: Econ-SCR-DSI-APH-ACI-ESP-Stack


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SO3 Tolerant PACs Provide a Dramatic Improvement in PAC Performance

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

0 1 2 3 4 5 6 7 8 9 10

Hg

Tota

l µg

/dsc

m

PAC Rate, lb/MMacf

Native Removal

~40% Reduction in ACI Rate

FastPAC Platinum Plus

With SO3 Tolerance

FastPAC Platinum Plus Without SO3 Tolerance

Operating Target

• Our Gen 5 FastPAC Platinum Plus with SO3 tolerant features reduced PAC injection rate by 43% over over a similar PAC without SO3 tolerant features.

7 ppm SO3


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Stable Capture without Re-emission of Mercury

• Mercury re-emission 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 capture of Hg can result in re-emission or leaching; oxidation without stable capture does not achieve control goals

• 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 –catch is that injecting halogens throughout the boiler and process has collateral effects


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• Three 750 MW units

• Western bituminous coal

• Low sulfur coal

• Two wet FGD absorbers/unit

• Hg 0.02-0.09 µg/g

• CaBr2 injection

• Activated carbon injection in wet FGD in

slurry form using STEAG technology

• Technology was selected

Field Test at Salt River Project –Navajo Generating Station

• SRP Navajo Unit 3 tested over a 4.5 month period

• Several technologies had been evaluated

• These results are using ADA-CS PowerPAC WS


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1.2 lb Hg/TBTU compliance level was achieved

No CaBr2 & No PAC

Met 30-Day Rolling Average for MATS Compliance with Calcium Bromide Treatment on Coal and PowerPAC WS in Wet FGD (A&WMA MEGA Symposium 2014 Paper #90)


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Key PAC Benefits for Wet FGD (LSFO) Applications

• No bulk chemistry/ORP impacts:

• For low ORP scrubbers, PAC does not impact ORP as do sulfide additives,

and this removes the risk of overshooting and impacting gypsum quality

• For scrubbers that do not monitor ORP, ORP and pH do not impact PAC’s

effectiveness

• Gypsum Preservation:

• In work by Southern Company and URS/AECOM, successful separation of

PAC from gypsum was achieved by tuning hydrocyclones. Marketing the

gypsum for wallboard or agricultural use have proven effective

• Low dosage for effective control:

• Southern Company tests showed that PowerPAC shifted the liquid phase

Hg to the solid phase (95%) at 200-300 ppm PAC addition


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Mercury Compliance While Avoiding Halogen/Oxidation-Driven CorrosionBOP Issues

• We have taken a fundamental scientific approach to examine each of pores, surfaces and

particles to optimize mercury capture based on specific flue gas requirements

• Use of laboratory tools and full-scale test feedback loop to drive Contact, Conversion and

Capture while tuning mercury removal to minimize reagent consumption and BOP impacts

• Some common takeaways:

o Use a low-volatility halogen salt (e.g. Sodium Bromide – NaBr)

o Use a halogen concentration that assures effective and efficient Hg oxidation but is

not in excess to cause BOP issues

o Design PACs so that the halogen is at the surface of the PAC particle to maximize

accessibility to the gas phase Hg and to insure efficient halogen utilization and apply

in a way that it is also less water extractable

o Use advanced Gen 4 and 5 PACs that require less consumption to reduce overall

halogen levels in your emission system

o Evaluate next-generation non- or low-halogen PAC technologies


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Intersections with Water and Solids

• Mercury can be partitioned in the gas, liquid, or solid phase and subsequently concentrated and sequestered by control technologies, but not destroyed; similar to Se and As - all key water and waste (RCRA) metals

• Philosophy of active control (a “control knob”)• Mechanistic approach to ensure completion of “Contact –

Conversion – Capture”• CaBr2 injection on coal has been shown to increase the scrubber

liquor Se content, increasing water treatment system loading• Secure capture needed to ensure ash and effluent streams are not

adversely affected• Reduced Hg and potentially Se loading to scrubber is beneficial for

future water discharge technologies – get them out as early as possible!

• Ash and other byproducts have value and utilization is increasing


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Criticality of Testing Programs

• How do the options impact your plant?

• Establish performance ranges for design input (define variables: coal type or quality, loads, evaluating test methods, etc)

• Get the measurements right – cross check methods

• Planning so the right things are measured - BOP

• Duration of test or demonstration is key to ability to extrapolate

Good white paper on testing published by the Institute of Clean Air Companies (ICAC) in 2013: “Conducting a Successful Mercury Control Demonstration Test at a Coal-Fired Power Boiler” at www.ICAC.com


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Provided by Robert Mastropietro of Nol-Tec Lodge Cottrell

Resistivity Guidelines


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Provided by Robert Mastropietro of Nol-Tec Lodge Cottrell


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Native Control is the First Step

• Example of native control: SCR, ESP and wet scrubber

• Pros:

• No reagent use except SCR ammonia or urea

• SCR provides oxidation

• Wet scrubber captures oxidized mercury


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Native Control has Limitations

• Example of native control:SCR, ESP and wet scrubber

• Cons:

• SCR oxidation/conversion of Hg may be inconsistent as catalyst

ages; no control knob to turn/passive control

• Insufficient oxidation results in pass-through of elemental Hg

• Wet scrubber is a large sink for mercury but may not be stable as

process conditions vary : re-emission risk

• Cycling up scrubber concentrations to reduce effluent flow is

limited by halogen content

• Ash and unburned carbon have a loose hold on mercury

captured in ESP; is it stable?


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Management and Technology Synergies

• Example of native control: SCR, ESP and wet scrubber

• Management:

• May be able to manage ORP and pH of scrubber

liquor to minimize re-emissions (challenging)

• Understanding the fate of emissions in each

individual system and trace metals fate requires

informed testing

• Water effluent management: stability of stream flow

and concentration into effluent treatment/bio

system is crucial


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• Remember scientific principles for “Conversion – Contact –Capture” and obtain accurate mass balances where achievable to confirm fate of trace species

• Assess the stability of those species and the process streams

• Engage “active” rather than “passive” controls

• Revisit compliance strategies as appropriate when new requirements or operating conditions develop (water discharge control, new coal, etc.)

• Remove the Hg upstream as far as possible to minimize entropy and utilize scrubber for primary purpose: acid gas control

• Always evaluate Balance-of-Plant impacts such as ash utilization, corrosion, scrubber chemistry, etc.

• Testing is critical to demonstrate results and effects

Guiding Principles


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Integrating the APC System to Maximize Native and Co-benefit Hg Capture

Coal Pretreatment

Combustion Oxidation

Dry Sorbent Injection

SorbentInjection

Wet Scrubber Additives

• Integrate technology options and actively manage mercury control.

• Maximize native capture of mercury.

Post Scrubber Treatments

Technology solutions need to be cost effective for Hg control and favorableto balance-of-plant considerations.


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Mercury Inventory and Projected Impact of MATS


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‹#›

References/Resources• Power Engineering article Nov 2016 “MATS and Beyond: The Role of Technology

Choices in Present and Future MATS Compliance”• Available in pdf format for download at http://www.ada-cs.com/news

• Power Magazine articles http://www.powermag.com• March 2014 “The Role of Activated Carbon in a Comprehensive MATS Strategy”• April 2015 “The State of U.S. Mercury Control in Response to MATS”

• www.ICAC.com• “Conducting a Successful Mercury Control Demonstration Test at a Coal-Fired Power

Boiler”• “Process Implementation Guidance for Powdered Sorbents at Electric Generating

Units”

• MEGA Symposium papers – 2014 and 2016 – available upon request• Aug 2014 “Field Demonstration of Advanced Activated Carbon for Mercury Control in

Wet FGD”• Aug 2016 “MATS Problem Solving: Advancing SO3-Tolerant Activated Carbons

Through Pilot Demonstration”

• World of Coal Ash (WOCA) paper April 2015 “Evaluating Impacts of Ash Quality of Powdered Activated Carbon for Mercury Control”

• DOE Energy Information Agency snapshot of MATS retrofits from 2014-April 2016:

• http://www.eia.gov/todayinenergy/detail.php?id=26972

http://www.ada-cs.com/news

http://www.powermag.com/


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Thank You and Questions?

Joe Wong

Chief Technology Officer

[email protected]

Sheila Glesmann

SVP Environmental and External Affairs

[email protected]

mailto:[email protected]

mailto:[email protected]

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