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

joe.wong@ada-cs.com

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