Mercury Monitoring

Barrett Parker, EPA Emissions Measurement Center

Basis for Mercury Monitoring

• Utility air toxics report to Congress– EPA made determination for MACT rule

• Proposed rule 1/30 (69 FR 4652)

• New PS included

• Comment period closed 3/30

Electric Utility MACT

• 12 month rolling average mercury emission limit

• Cap and trade system is an alternative

EMC Involvement

• Collected data on mercury monitors

• Made recommendations for proposal

• Partnered with CAMD, ORD, NIST, EPRI

Test Objectives

• Determined– Ability for reliable data over time– Durability, availability, maintenance

requirements– Suitability of draft PS-12 for CEMS

• Investigated all types of mercury monitors– Sought options for flexibility and accountability

Monitoring Types

• Periodic Testing (ASTM D 6784-02, M29)– Reference method

• Continuous collection, delayed analysis (sorbent tube)

• Continuous collection and analysis (CEMS)– Wet conversion, dry conversion, other

Monitoring Types (continued)

• CEMS and sorbent tube selected– Requested comments on monitoring for

sources emitting less than 25 pounds of mercury per year

German Experience

• Mercury CEMS on Incinerators– No requirements for coal-fired power plants

• Visited six incinerators– One co-fired lignite to produce electricity

• Sources are well controlled– ESPs, scrubbers, carbon adsorption, and

SCR

• 3rd party instrument certification

Test Phase Description

• Phase I (summer 01)– 140 MW firing bituminous coal with cold side

ESP– Use 2 German-certified CEMS

• Phase II (fall 02)– Same site– Use 6 CEMS and EPRI monitor

Test Facility During Phase II

• Instruments (left to right)– Envimetrics, Mercury Instruments, Genesis, Opsis,

Durag, PS Analytical

EPRI’s Carbon Tube Sampler

Test Phase Description (continued)

• Phase III Pilot (spring 03)– Low level detection and interference checks– Pilot scale facility firing natural gas and lignite,

bituminous, and subbituminous coals– Use 3 CEMS and EPRI monitor

Test Phase Description (continued)

• Phase III (summer 03)– 550 MW firing subbituminous coal with dry

FGD, SCR, and baghouse– 5 CEMS and EPRI monitor

Test Phase Description (continued)

• Phase IV (fall 03)– 440 MW firing bituminous coal with wet FGD

and reverse-air baghouse– 2 CEMS and EPRI monitor– 3 three-hour test periods

Phase I - Initial

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Phase I - Initial

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RM CEMS #1

Phase I – Final

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Phase I - Final

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RM Wet CEMS CEMS #2

Phase II - Initial

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Phase II - Initial

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RM Wet CEMS CEMS #2 CEMS #3

Phase II - Final

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Phase II - Final

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RM Wet CEMS CEMS #2

CEMS #3 CEMS #4 CEMS #5

Xray CEMS

Phase III - Pilot Scale

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RM avg

Phase III - Pilot Scale

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RM avg Wet CEMS CEMS #6 CEMS #4

Phase III - Initial

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Phase III - Initial

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RM CEMS #2 CEMS #4

CEMS #5 CEMS #6 Xray MS

Selected Phase III – Initial Runs

Run

RM

RM dup

CEMS #6

CEMS #2

CEMS #4

CEMS #5

Xray MS

1 1.36 1.26 1.2 1.6 1.0 1.08

2 5.34 3.05 2.9 2.3 2.4 2.75

4 1.50 1.50 1.5 1.4 1.5 1.38

6 6.91 4.22 4.4 4.7 3.8 4.39

8 14.27 10.1 13.4 11.8 3.4 19.00

11 3.33 3.36 3.2 3.2 3.1 1.1 3.37

Phase III - Final

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Phase III - Final

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RM CEMS #2 CEMS #4

CEMS #5 CEMS #6 Xray MS

DRAFT Phase IV - Initial

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RM 1 avg RM 2 avg

DRAFT Phase IV – Initial and Proposed MACT Limit

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RM 1 avg RM 2 avg CEMS #4 avg

CEMS #6 avg 10% Limit

DRAFT Phase IV – Initial and Proposed MACT Limit (Rescaled)

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CEMS #6 avg 10% Limit

DRAFT Phase IV - Final

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DRAFT Phase IV – Final and Proposed MACT Limit

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RM 1 avg RM 2 avg CEMS #4 avg

CEMS #6 avg 10% Limit

DRAFT Phase IV – Final and Proposed MACT Limit (Rescaled)

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CEMS #6 avg 10% Limit

Findings

• No sample loss in 200 feet of line

• Monitors improving between Phases

• Monitors can meet RA requirements of draft PS-12, but low-level correction needed

Findings (continued)

• Dual train reference method testing is important

• Monitors can operate for up to 3 months with routine maintenance

Products

• Monitoring operational characteristics and costs

• Data for GPRA report on Mercury CEMS and coal combustion

• Proposed PS 12A– Covers only vapor phase (no particulates)– Designed for fossil fuel fired boiler exhaust– Allows use of existing equipment

Products (continued)

• Proposed PS 12A (continued)– Requires at least 9 paired sets of 2 hour

(minimum) runs– Allows up to 3 sets to be rejected– Specifies results to be within 20% of reference

method or 10% of MACT limit– Identifies outliers as

• RSD > 10% if mercury > 1 μg / m3 or• RSD > 20% if mercury 1 μg / m3

Products (continued)

• Proposed PS 12A (continued)– Requires measurement error test using NIST

traceable Hg0 and HgCl2 at zero, mid, and high levels

• Calibration standards from NIST – Certified elemental mercury in cylinders

• 2, 5, and 20 micrograms per cubic meter

– Ionic mercury to follow (1/06)

Concurrent Activities

• Assist R2 and NJ with PSEG’s NSR settlement

• Monitor and assist State rulemakings

• Coordinate with ETV mercury CEMS Phase III

Next Steps

• Respond to proposal comments

• Potential additional testing– Longer term subbituminous and bituminous

coals with cold side ESP