77 West 200 South, Suite 210

Salt Lake City, Utah 84101

Tutorial: Tutorial:

Mercury Chemistry in B

Mercury Chemistry in B

and

Mercury Control Technology 

Mercury Control Technolog

Presented by

Connie Senior (senior@reaction-eng.com

April 17-21, 2005

30th International Technical Conference on Coal Utilizatio

Clearwater, Florida
Course Objectives

• Mercury comes into the boiler in the coal• Sometimes mercury can be removed from the 

not always

• Mercury comes in different “flavors” (species

• Mercury speciation in flue gas is not “magic”• The “flavor” of mercury in the flue gas affects 

mercury is removed before the stack

• Existing air pollution control devices remove 

mercury from flue gas

• Mercury control technologies have been used 

commercially on incinerators, but not on elecboilers

• The most mature technology (demonstrated f

than six months) is activated carbon injection baghouse
Mercury Inputs to the B

0%

20%40%60%80%

100%

0 0.1 0.2 0.3 0.4 0.5

Hg content, ug/g

%Less than value

Petcoke

Tires

Subbituminous

Bituminous

Lignite

ICR Part II data for 4th quarter 1999 were taken from this site and analyzed: 

http://utility.rti.org/part2/summaryP2.cfm
http://ugs.utah.gov/emp/mercury/index.htm 
Can Hg in Coal Be Pred

• Da• Ex

frocose

• Hg • Tre

buge

0.00.10.20.30.40.5

0 5 10 15 20 25 30

Ash, wt% dry

Mercury, ug/g dry

Allegheny (Pittsburgh)Allegheny (Tyson)Allegheny (various)Garrett (Mahoning)Garrett (Upper Freeport)Garrett (various)
Can Hg in Coal Be Pred

• Da• Ex

frocose

• Hg • Tre

buge

0.00.10.20.3

01234

Sulfur content, wt% dry

Mercury content, ug/g dryHopkins - Kentucky #11 Hopkins - Kentucky #4 Knott - Elkhorn #3 Knott - Hazard #4
Can Mercury Be Remo

• Bituminous coals:

– On a limited basis, mercury content f

in sulfur or ash – no general relations

– Coal washing may reduce mercury f

coal sources – limited application
Can Mercury Be Remo

• Subbituminous coals:

– Mercury organically bound in coal– Mild heating (e.g., K-Fuel process, W

removes some mercury

– Cost?

Source: B
How Does Mercury Get into 

It starts with the fuel... 

Fuel

Bottom Ash Bottom Ash

Fly Ash Fly Ash

FGD Byproducts and FGD Byproducts and 

Waste

...but doesn’t all get to t

...but doesn’t all get to t
What Do We Mean by Spe

• Gas-phase mercury:

– Elemental: Hg

0

– Oxidized: Hg+2 (HgCl

2, other species

• Particulate mercury

– Hg

p

– Mercury (adsorbed on particles)
Why Do We Care About Spe

-50%-25%

0%

25%50%75%

100%125%150%

10 100 1,000 10,000

Coal Chlorine, ppm dry

Hg Removal Elemental Oxidized

Werem

~9

<25

=> in affin 

Source: ICR data de
Mercury Chemistry in Flu

HgCl

2

Gas

-phase 

reactions reactions

Hr

Hg

0 Hg

Adsorption Adsorption

Oxidation Oxidation
Mercury Speciation in Com

Systems

• Sp

to codeanco

Fraction of particulate mercury in flue gas at inlet to particulate control (Source: ICR data)

0%

20%40%60%80%

100%

10 100 1,000 10,000

Coal Chlorine, ppm dry

% as Hg p at Inlet
http://ugs.utah.gov/emp/mercury/index.htm 
-20%

0%

20%40%60%80%

100%

ESP Baghouse Spray

DryerBaghouse

Wet

Scrubber

Mercury Removal

BituminousSubbituminousLignite

Mercury Captured by Air P

Control Equipmen

Source: E
Mercury Captured by Air Po

Control Equipment

Boiler

Burners

Air

Heater

Fuel

Coa l P ulveriza tion Coal Supply

P articulate Collector S O2

Scrubber

Stack

Boiler SCR

Burners

Air

Heater

Fuel

Coa l P ulveriza tion Coal Supply

P articulate Collector S O2

Scrubber

Stack

SCR

...a walk throug
Oxidation Across Full-Scale 

• Full• Lar

obs

• Low 

PRB coa

0%

20%40%60%80%

100%

0 500 1000 1500 2000

Coal chlorine, ug/g

Oxidation of Hg 0 Across SCR

NH3 OnNH3 Off
Oxidation of Hg Acros

0%

20%40%60%80%

100%

0 200 400 600 800 1000 1200 1400 1600

Coal Chlorine, ug/g

Change in Hg 0 across APH

No SCR (low S)No SCR (med/high S)SCR (low S)SCR (med/High S)

• • • 
Hg Removal in PCD

From ICR • High l

possib

• ESPs 

remov

• Hot-si

remov

0%

20%40%60%80%

100%

10 100 1,000 10,000

Coal Chlorine, ppm dry

% Removal of Hg

FFCESPHESP
Removal of Total Hg Acro

• • • 

0%

20%40%60%80%

100%

0% 10% 20% 30% 40% 50%

LOI %

%Hg Removal Across ESPDe Vito, et al. Sjostrom et al. Plant C Plant D Plant E Fit to PC/CESP data Hot-side ESP Stoker Cyclone

Source: Senior and Johnson, 2005
Activated Carbon v. Fly A

• A

ccrf(

0%

20%40%60%80%

100%

0% 10% 20% 30% 40% 50%

LOI %

%Hg Removal Across ESP

De Vito, et al.Sjostrom et al.Plant CPlant DPlant EFit to PC/CESP dataACI

Hot-side ESP

Stoker

Cyclone

Source: Senior and Johnson, 2005
Mercury Removal in Dry S

• S

dffcufc

Source: ICR data

ICR SDA/FF Data

-20%

0%

20%40%60%80%

100%

10 100 1000 10000

Coal Cl, ug/g dry

Removal of Hg across SDA/FF

BituminousLigniteSubbituminous
Mercury Removal in Dry S

• S

dffcufc

• F

aesc

Source: ICR data

ICR FF Data with and without SDA

-40%-20%

0%

20%40%60%80%

100%

10 100 1000 10000

Coal Cl, ug/g dry

Removal of Hg 

BituminousLigniteSubbituminous

(Open symbols are FF only)
Mercury Removal in Wet S

Source: ICR data

ICR ESP/FGD Data

0%

20%40%60%80%

100%

10 100 1,000 10,000

Coal Cl, ug/g dry

Removal of Hg across ESP/FGD

BituminousLigniteSubbituminous

• Spe

FGremscr

• Str

inc

FGdis
Behavior in Existing APCDs: 

• Vapor-phase species:

– Elemental: difficult to remove from gas– Oxidized: soluble in wet scrubbers, ad

more readily by some sorbents

• Hg found in vapor-phase and bound to pa

matter; partitioning depends on 

– carbon content– particulate control device (ESP vs. FF)– NO

x control (post-combustion, SCR) 

– coal type (bituminous vs. low rank)

• Significant removal of Hg possible in 

APCDs
Mercury in Byproduc

• Mercury is already removed by

– Fly ash– Scrubber sludge (FGDs)

• Where does it go?
Use of Fly Ash from Coal Co

Estimates for Source: Kilgr

Fate Millions 

of tons 

% Potential release me

Land disposal 42.210 67.0% Leaching, windblowConcrete/grout 10.000 15.9% Leaching, volatilizat

(application-specific

Structural fills 3.200 5.1% Unlikely Waste stabilization 1.900

3.0% Unlikely 

Mining applications 

1.500 2.4% Leaching 

Raw feed for cement kiln 

1.300 2.1% Volatilization in the 

recovery in fines 

Road base/subbase 

1.200 1.9% Not expected to be s

Flowable fill 0.850 1.3% Unlikely Other 0.840 1.3% Total 63.000 
Leaching of Hg from Fly 

• Results to date show little Hg leaches fro

standard tests

Source: Senio

Hg in 

TCLP 

Salem S.American bituminous 0.034 

Brayton Eastern bituminous < 0.01Brayton Eastern bituminous 0.02 Brayton Eastern bituminous 0.02 

Plant Coal
Distribution of Hg in FGD 

• M

eba

• O

c

• R

re

Source: Richardson, et al., 2003

0

20406080

100120140

Bit/LSF

Bit/LSF

Bit/LSF

Bit/LSI

Bit/LSN

Bit/LF

PRB/LSF

TX Lig/LSF

TX Lig/LSI

%Hg in Coal

Fines LiquorGypsum FinesFGD ByproductFly Ash

LSF = Limestone Forced OxidationLS = Lime Forced OxidationLSI - Limestone Inhibited OxidationLSN = Limestone Natural Oxidation
Mercury Control Techn

Source: Offen, et al., 2005

Stage Process1. Laboratory Novel sorbents2. Pilot scale

Novel sorbents, oboiler and SCR H

3. Full scale: capabilities/limits

Combustion modsorbents, chemicTOXECONTM II

4. Full scale: multiple sites

ACI, Chemically tSCR/FGD

5. Long term: 12-18 months TOXECONTM 

6. Widespread implementation ---
Activated Carbon Injectio

Demonstrations

Source: US EPA, 2005

APC Configuration Bituminous Subbituminous LigniteC-ESP Hudson* Pleasant Prairie 2 Leland O

Brayton Point 1 Powerton* Coal CrSalem Harbor 1 St. Clair 1 Stanton Yates 1,2 Meramec Poplar RValley* Miller*Lausche MonroeMiami Fort IndependenceAllenConesville

H-ESP Cliffside none noneFF none Comanche 2* Spruce

Pleasant Prairie*Presque Isle

SDA/FF none Holcomb Stanton 

Antelop

SDA/ESP Laramie River 3PS none Laskin 2 none

*Pilot-scaleItalics denote testing that has not been completed (March, 2005)
ACI – Required Equipm

Source: Sjo

Sorbent Storage Hg 

Sorbent Injection
Darco Hg Sorbent

• Lig

ac

• 60

are

• MM

0%5%

10%15%20%25%30%35%40%

2.0 2.9 5.0 10.0 18.6 44.0 55.5 60.9 74.0

Average size in bin, microns

Mass in bin

*Formerly called DARCO FGD
ACI with ESP

Source: ADA ES

Sorbent Injection

Ash and Sorbent

ESP

Ash and Sorbent

ESP
ACI in ESP:

Sorbent Injection at Pleasant 

Spray Cooling

Carbon Injection

Mercury Analyzer

Mercury Analyzer

ESP 2-4 

ESP 1-2 

Spray Cooling

Carbon Injection

Mercury Analyzer

Mercury Analyzer

ESP 2-4 

ESP 1-2 
Injectors, Geometry and G

Source: C
Effect of Mixing on Hg

0 Rem

• CFD Si

SorbenHg rem

• Distribu

gas

• 10 lb/M

injectio

• One-th

occurs 

⇒ high ⇒ goo

Hg

0 removal 32.6%

Hg

0 removal 29.2%

Hg

0 removal 26.5%

Hg0 removal 10.9%

Hg

0 removal 32.6%

Hg

0 removal 29.2%

Hg

0 removal 26.5%

Hg0 removal 10.9%

Source: C
Summary of ACI Demons

DARCO Hg & Plants with 

Source: Sjo

Cold-Side ESP Units

0

20406080

100

0 5 10 15 20 

ACI Rate, lb/MMacf

%Hg Removal St. Clair Meramec Pleasant Pra

Coal CreekStantonLeland OldsBrayton Poin
Summary of ACI Demons

DARCO Hg & Plants with 

0%

20%40%60%80%

100%

0246

ACI Rate, lb/MMacf

% Hg Removal Holcomb (PRB)

Stanton (Lignite

Source: Sjo
EPRI TOXECONTM

Sorbent Injection

~1% Sor

ESP

P

Sorbent Injection

~1% Sor

ESP

P

Source: ADA ES
Summary of ACI Demonstra

DARCO Hg & Plants with F

• Gas

demmon

• Full-

TOXsysteconsEneIsle

FF Units

0

20406080

100

0 5 10 15 20 25

ACI Rate, lb/MMacf

%Hg Removal Gaston Subbit (Pilot)

Bit (Pilot)

Range of ESP data
General Trends in ACI:

Single Sorbent (DARCO H

All Units

0%

20%40%60%80%

100%

0 5 10 15 20 

ACI Rate, lb/MMacf

% Hg Removal ESP SDA/FF

FF
Leaching of Hg from ACI +

• Inj

achaincmefro

Source: Senio

Hg in (μg/L)

TCLP SGLP

Salem S.American bituminous 0 0.034 < 0.010

Salem S.American bituminous 10 < 0.010 < 0.010

Salem S.American bituminous 10 < 0.010 < 0.010

Brayton Eastern bituminous

0 < 0.010 0.01

Brayton Eastern bituminous 0 0.02 0.05

Brayton Eastern bituminous 10 0.07 0.03

Brayton Eastern bituminous 0* 0.03 0.01

Brayton Eastern bituminous 20 < 0.010 0.01

Brayton Eastern bituminous 0* 0.02 0.02

Gaston COHPAC B-Side 1.5 0.01 <0.01Gaston COHPAC B-Side 1.5 <0.01Gaston COHPAC B-Side 1.5 <0.01 <0.01

Prairie PRB 10 <0.01 <0.01Prairie PRB 10 <0.01 <0.01Prairie PRB 10 <0.01

*Old ESP

Plant Coal

Injection 

Rate 

lb/Macf
ACI+ESP Cost Estima

Source: US EPA, 2005

Estimated sorbent and disposal costs for injection upstream of a c

Cold-Side ESP Units

0

20406080

100

0 0.5 1 1.5 2 2.5

Sorbent and Sorbent Disposal Costs, mills/kWhr

%Hg Removal Bituminous

Subbit/Lignite
ACI+FF Cost Estima

Source: US EPA, 2005

Estimated sorbent and disposal costs for injection upstream of a fa

FF Units

0

20406080

100

0 0.5 1 1.5 2 2.5

Sorbent and Sorbent Disposal Costs, mills/kWhr

%Hg Removal Bituminous

Subbit/Lignite
Summary

• Mercury comes into the boiler in the coal• Sometimes mercury can be removed from the 

not always

• Mercury comes in different “flavors” (species

• Mercury speciation in flue gas is not “magic”• The “flavor” of mercury in the flue gas affects 

mercury is removed before the stack

• Existing air pollution control devices remove 

mercury from flue gas

• Mercury control technologies have been used 

commercially on incinerators, but not on elecboilers

• The most mature technology (demonstrated f

than six months) is activated carbon injection baghouse
References

• Alan Bland, Kumar Sellakumar, Lyle Johnson, Gary Walling, Duane Steen, and Edgar Klunder, “Mercu

Fired Power Plants by a Pre-Combustion Thermal Treatment Process - An Update,” presented at 8th A

Environmental Conference, Tucson, AZ, January 24-26, 2005.

• Cremer, M., Senior, C., Chiodo, A., Wang, D., Valentine, J., "CFD Modeling of Activated Carbon Injectio

Fired Power Plants," presented at Electric Power Conference 2005, Chicago, IL, April 4-7, 2005.

• Angela Jenkins and John M. Holloway III, “State Efforts to Get Ahead of the Feds in Regulating Emissi

presented at 8th Annual Electric Utilities Environmental Conference, Tucson, AZ, January 24-26, 2005.

• Kilgroe, J.D., Sedman, C.B., Srivastava, R.K., Ryan, J.V., Lee, C.W., Thorneloe, S.A., 2001, Control of 

Fired Electric Utility Boilers: Interim Report, U.S. Environmental Protection Agency, Office of Research Risk Management Laboratory, Air Pollution Prevention and Control Division, EPA-600.R-01-109, Decem

• George Offen, Ramsay Chang, Paul Chu and Richard Rhudy, “Mercury Control for Coal-fired Power Pla

Options,” presented at 8th Annual Electric Utilities Environmental Conference, Tucson, AZ, January 24

• Quick, J.C., Brill, T.C., and Tabet, D.E., Mercury in US coal – observations using the COALQUAL and 

Geology 2003, 43, 247-259.

• Richardson, M.K., Blythe, G.M., Golden, D., “Mercury Stability in FGD Byproducts”, presented at the DO

Combined Power Plant Air Pollutant Control Symposium - The Mega Symposium, Washington, DC, Ma

• Senior, C.L., Bustard, C.J., Durham, M.D., Baldrey, K., "Characterization of Fly Ash from Full-Scale De

for Mercury Control on Coal-Fired Power Plants," Fuel Processing Technology 2004, 85, 601-612.

• Senior, C.L., Johnson, S.A., “Impact of Carbon-in-Ash on Mercury Removal across Particulate Control D

Plants,” Energy & Fuels 2005, in press.

• Sharon Sjostrom, Travis Starns, Jerry Amrhein, Jean Bustard, Wayne Penrod, Corey Lineville, Rich Ph

O'Palko, Ramsay Chang, “Full-Scale Evaluations of Mercury Control Technologies with PRB Coals,” pr

Utilities Environmental Conference, Tucson, AZ, January 24-26, 2005.

• US EPA, “Control of Mercury Emissions from Coal Fired Electric Utility Boilers – An Update,” February 

http://docket.epa.gov/edkpub/do/EDKStaffItemDetailView?objectId=090007d48068b4aa.