© 2012ADA-ES

Mercury Measurement and Control

Sharon Sjostrom & Connie Senior

ADA Environmental Solutions

NASDAQ: ADES www.adaes.com

Hot Topic Hour

April 12, 2012

© 2012ADA-ES

Topics to Cover

• Overview of MATS for existing & new plants

• Measurement of Hg

• Capabilities of available control technologies for

mercury control

• Coal to Stack: Integrated approaches for multi-

pollutant compliance

© 2012ADA-ES

MATS Final Limits (Coal)

• Standards for new units are based on outputs Subcategory Filterable PM HCl Mercury

New coal, 0.007 lb/MWh 0.0004 lb/MWh 0.0002 lb/GWh

≥8300 Btu/lb

New coal, 0.007 lb/MWh 0.0004 lb/MWh 0.040 lb/GWh

<8300 Btu/lb

Existing coal, 0.30 lb/MWh 0.020 lb/MWh 0.013 lb/GWh

≥8300 Btu/lb

Existing coal, 0.30 lb/MWh 0.020 lb/MWh 0.040 lb/GWh

<8300 Btu/lb

• Standards for existing units are based on inputs

• Standards for new units (bituminous,

subbituminous) are ~65 times lower than for

existing units!

© 2012ADA-ES

Mercury Measurement

• Continuous measurement of Hg required

– CEM or Sorbent Trap

• Emissions averaging

– For existing bituminous/subbituminous units, limit of

1.2 lb/TBtu (30-day average) or 1.0 lb/TBtu (90-day

average)

• Facility-wide averaging for similar units

• Challenges in measuring very low levels of Hg

© 2012ADA-ES

The Compliance Challenge

• Integrated Decisions

Multiple regulations. Decisions on one pollutant may affect

options for others

Long-range, multi-plant CapEx decisions, fuel decisions

• Tight Timeframes

Implementation by 2015 for MATS and CSAPR

Rapid, informed decisions are now required

• Limited Resources

Testing Services, Engineering and Construction Services,

APC Equipment, Chemicals

© 2012ADA-ES

Fuel Choice Affects MATS Compliance

• Mercury inputs vary by region and by mine

within a region

MATS sets limits on Hg emissions, not percent

reduction

The bar is higher (for control) when Hg input is higher

• SO2 and HCl emissions might also have to be

controlled under MATS (or CSAPR)

• Sulfur and chlorine in coal affect ability to reduce

Hg emissions

• Finding the perfect MATS coal…?

© 2012 ADA-ES

MATS Compliance Limits:

Example for Existing Bituminous Plant

Final MACT Limits:

PM,

lb/MMBtu

HCl,

lb/MMBtu

SO2,

lb/MMBtu1 Hg, lb/TBtu

0.03 0.002 0.2 1.2

Estimated control efficiency, based on fuel:

HCl SO21 Mercury

98% 97% 86%1Alternate acid gas l imit for units with scrubbers2Concentrations at 3% O2

INPUT COAL PROPERTIES

Coal Rank Coal S, wt% Coal Ash, wt% Coal HHV, Btu/lb Coal H2O, wt% Coal Cl, µg/g Coal Hg, µg/g

Bituminous 3.60% 10.30% 11,011 3.30% 1000 0.1

As-received coal composition Dry coal composition

© 2012ADA-ES

Factors Affecting Mercury Control

• Coal Type

Halogen content (Cl, Br, other)

Sulfur content

Mercury content

• Flue Gas

Acid Gases (HCl, SO2, SO3)

Gas Temperature

• Boiler type

• Emission Control Equipment (e.g. SCR, ESP, FF, etc.)

• ACI Design

Distribution, residence time, sorbent characteristics

Similar factors affect

Hg removal from

native carbon in ash

and activated carbon

injection

© 2012ADA-ES

Native Mercury Removal (Average %):

The Good, the Bad, and the Ugly… Bituminous Subbit. Lignite

CSESP 41 17 -2

+ WFGD 73 21 45

HS ESP 22 14

+ WFGD 44 25

FF 87 71

+ WFGD 78

SDA + FF 95 31 29

SDA + ESP 50 50

WPS 14 -2 30

Projected

for MATS

80-90+ 80-90+ 60-90+

Analysis of 1999 EPA ICR data

© 2012 ADA-ES

SCR plus FGD Increases Hg Removal

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Plant 6, U4

(SCR off-line)Plant 6, U4 Plant 7, U1

(SCR off-line)Plant 7, U1

Tota

l Hg

Rem

ova

l

Source: Bituminous-fired plants

from Consol sampling program

© 2012 ADA-ES

SCR-FGD Reduces Hg Emissions

Source: Bituminous-fired plants

from Consol sampling program

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Plant 3, U2

Plant 4, U1

Plant 4, U2

Plant 5, U1

Plant 6, U4

Plant 7, U1

Plant 8, U1

Plant 9, U1

Plant 10, U2

Tota

l Hg

Rem

ova

l

…but >90% removal not always achieved

and trim control with ACI might be needed

© 2012ADA-ES

Halogens Increase Oxidized Mercury

0

20

40

60

80

100

0 500 1000 1500 2000 2500 3000

Halogen in Coal, ppmw dry

%O

xid

ize

d H

g a

t A

ir P

reh

ea

ter

Ou

tle

tNaCl

MgCl2

CaCl2

HCl

CaBr2

Halogen addition at various full-scale PRB boilers

Source: Dombrowski et al., 2006

© 2012ADA-ES

Benefits of Oxidized Mercury

Many plants’ APCDs can take advantage of native

capture…if there’s enough oxidized Hg (Hg2+)

0%

20%

40%

60%

80%

100%

0% 20% 40% 60% 80% 100%

Rem

oval of

Hg a

cro

ss F

GD

Fraction Hg2+ at Inlet

Dry FGD, FF

Wet FGD

© 2012ADA-ES

Halogens in Wet Scrubbers

• Adding halogens (Cl or Br) increases oxidized Hg,

which increase capture of Hg in scrubber

• Wet FGD scrubbers remove halogens efficiently

– Average Cl removals for wet FGDs (2010 ICR): 81% for

subbituminous, 97% for bituminous

– Removal of Br at Plant Miller wet FGD: 94-96%

(Dombrowski et al., 2008)

• Halogens build up in wet scrubber liquor

© 2012ADA-ES

Corrosion in Flue Gas

• Indirect evidence that HBr

might be more corrosive

than HCl at flue gas

temperature

• No direct comparison, but

HBr corrosion higher than

baseline (no HBr) in

simulated flue gas

(6-month study)

0

0.02

0.04

0.06

0.08

0.1

0.12

0 100 200 300 400

Co

rro

sio

n l

oss

, m

m

Temperature, oF

Baseline

51 ppmv HBr

• Chlorine corrosion in furnaces can occur for very

high levels of chlorine in coal (> 2000 µg/g)

– Bromine addition at much lower concentrations

Zhuang et al., 2009

© 2012ADA-ES

US Coal-Fired Generation Fleet

More than 1100 units in

operation

~ 317 GW

~ 66% have SO2 or

NOx controls

Unscrubbed units

~ 50 GW bituminous

~ 60 GW subbituminous

*http://www.eia.gov

0

20

40

60

80

100

120

140

Ge

ne

rati

on

(G

W)

FGD+SCR

SCR

FGD

None

© 2012ADA-ES

Activated Carbon Injection

Configuration Range of AC for 90% Control

(lb/MMacf)

PRB/SDA/FF 1 to 3

PRB/Toxecon 2 to 4

Bit/Toxecon 2 to not achieved

PRB/ESP 2 to not achieved

Bit/ESP 2.5 to not achieved

EPA Estimates 141 GW new ACI

© 2012 ADA-ES

Activated Carbon Injection

Performance Depends on Fuel Choice

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 Injection Concentration (lb/MMacf)

Hg

Re

mo

va

l (%

)

PRB ESP

SDA + FF

LS Bit ESP

ESP with SO3

Conditioning

HS Bit ESP

© 2012ADA-ES

SO3 Injection and PAC Effectiveness • Any SO3 in gas phase appears to affect Hg capture

– SO3 is used to condition fly ash for better capture in ESPs

– SO3 higher in bituminous flue gas, especially after SCR

• Typical injection targets < 10ppm in gas phase

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10

PAC Injection (lb/MMacf)

Hg R

emoval

(%)

No injected SO3

5.4 ppm SO3

10.7 ppm SO3

Ameren Labadie Data: DOE DE-FC26-03NT41986 and

EPRI PRB, ESP

0

20

40

60

80

100

0 2 4 6 8 10

SO3 Off

SO3 On

Sorbent Injection Ratio (lb/MMacf)

Mer

cury

Rem

ov

al (%

)

Mississippi Power Plant Daniel

Low sulfur bituminous coal

© 2012ADA-ES

Compliance Strategies for Mercury

• 80 to >90% control at the stack to meet proposed

MATS emission limits required for most units

• For units with FGD/SCR:

Low conversion SCR catalyst and minimize ammonia slip

Minimize re-emission of Hg0 from wet FGD

• MATS limits achievable with ACI or ACI + coal

additives on most subbituminous units if SO3 flue

gas conditioning (FGC) is eliminated

• MATS limits may be challenging on units with

higher sulfur coals and may require SO3 mitigation

© 2012ADA-ES

Coal to Stack: Integrated

Approaches for Multi-Pollutant

Compliance Examples:

Fuel (low mercury, low sulfur, low chlorine)

DSI as required to meet HCl limits and/or control

SO3 to maximize ACI effectiveness

Manage SCR operation and catalyst choice to

increase fraction of oxidized mercury and

resulting removal in WFGD

Utilize coal additives to manage ACI usage and

Hg removal effectiveness

© 2012 ADA-ES

DSI-ACI Synergy: Example

Medium-sulfur

bituminous plant

Lime injection to

reduce SO3 =>

improve ACI

performance for Hg

control

0

20

40

60

80

100

0 5 10 15 20

% V

ap

or-

ph

ase R

em

oval w

rt B

aselin

e M

easu

rem

en

t

Sorbent (lb/MMacf)

Shawville 3, ESP 1 Darco Hg

Shawville 3, ESP 1 Lime/Darco Hg

© 2012 ADA-ES

DSI-ACI Synergy: Example

Low-sulfur bituminous plant with SCR

Trona injection to reduce SO3 => improve ACI

performance for Hg control

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20

% V

ap

or-

ph

as

e R

em

ov

al

Sorbent (lb/MMacf)

Merrimack 2, Darco Hg-LH

Merrimack 2, Darco Hg-LH, APH In, normal CEA

Merrimack 2, Darco Hg-LH, Trona, normal CEA

Merrimack 2, Darco Hg-LH, Trona, low CEA

Merrimack 2, Darco Hg-LH, Mill Trona, low CEA

Effect of SO3 sorbent

Effect of temperature

Effect of milling

© 2012ADA-ES

Summary: The Multi-Pollutant View Mercury

• 80 to >90% control required for most units

• Achievable on most subbituminous units if

SO3 FGC is eliminated

• Limits may be challenging on units with higher sulfur

coals and may require SO3 mitigation

HCl

• > 90% control required for most bituminous units. May

require new scrubbers for some units.

• < 80% control required for most plants with low-rank

coals. Should be achievable with fuel management,

DSI or existing FGD for most plants.

Total PM

• May result in several new fabric filters

ADA Environmental Solutions

(303) 734-1727

Energizing the Future with

Cleaner Coal

NASDAQ: ADES www.adaes.com