Implementation of Clean Air Act Requirements for Advanced Coal Technologies

CoalFleet Program Update and Workshops

Kingsport, TN

July 26–28, 2005

Implementation of Clean Air Act

Requirements for

Advanced Coal Technologies

Steve Jenkins

Tampa, FL

Advanced Coal Technology Work Group

March 6, 2007

Topics

• Bob Wayland has discussed overall CAA:

–

Rules and how they apply to utility sector

–

Timeline

–

Regulatory process

–

Projected emissions and retrofits to comply with CAIR, CAMR,
CAVR

–

BACT and LAER

• Now let’s see how ACTs that being planned are going to

comply with these rules:

–

How emission control systems for PC and IGCC are different

–

Focus on New Source Performance Standards

–

How emission limits compare

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CoalFleet Program Update and Workshops

Kingsport, TN

July 26–28, 2005

Applicable Air Regulations

• National Ambient Air Quality Standards (NAAQS)
• New Source Review (NSR) requirements, including

Prevention of Significant Deterioration (PSD) and Non-
Attainment NSR; and BACT/LAER

• New Source Performance Standards (NSPS)

• National Emission Standards for Hazardous Air

Pollutants (NESHAPs) including proposed Utility MACT
and Combustion Turbine MACT rules

• Federal Acid Rain Program (Title IV)
• Operating permit (Title V)
• Clean Air Interstate Rule (CAIR)
• Clean Air Mercury Rule (CAMR)

Technology Comparison

IGCC

Feedstock

Coal

Fuel

Coal

Syngas

Combustion

Coal in boiler

Syngas in gas turbine

Emission Control

Post-combustion

clean-up of large

volume of exhaust gas

Pre-combustion

clean-up of small

volume of syngas

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CoalFleet Program Update and Workshops

Kingsport, TN

July 26–28, 2005

NOx

Mercury

Limestone-
based FGD

system

Low-NOx

burners and SCR

ESP or

baghouse

Inject

activated

carbon into

flue gas

IGCC

Amine

system

removes

S from

syngas

Syngas

saturation and N

diluent

Wet scrubber,

high

temperature

cyclone,

ceramic filter

Pre-sulfided

activated

carbon bed

in syngas

stream

IGCC - a Different Environment Than PC

• Gasification occurs in a reducing

atmosphere

– sulfur compounds are liberated as H

S and

COS

– removed by refinery industry technologies to

levels

≥

99%

• Low levels of H

S in the syngas are

burned in the gas turbine and become
SO

in exhaust

• NOx is controlled by injecting N

at ~1:1

ratio with syngas, as well as saturating
the syngas stream with water or steam
(cools the flame)

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Comparison of Air Emission Controls:
PC and IGCC

CoalFleet Program Update and Workshops

Kingsport, TN

July 26–28, 2005

New NSPS

Emission

NSPS

NSPS on Input

Basis for IGCC

(estimated

)

NSPS on Input

Basis for PC

(estimated

)

NOx

1.0 lb/MWh*

0.132 lb/MMBtu

0.11 lb/MMBtu

1.4 lb/MWh* and

minimum 95% removal

0.185 lb/MMBtu

0.155 lb/MMBtu

Lesser of 0.14 lb/MWh*

or 0.015 lb/MMBtu

0.015 lb/MMBtu

Mercury

20 x 10

-6

lb/MWh*

(bituminous)

2.6 lb/TBtu

2.2 lb/TBtu

*output-based standards are on a gross generation basis,

so gross heat rate is used to calculate estimated input-based limit

New Source Performance Standards

• NSPS for Electric Utility Steam Generating Units

(Subpart Da), February, 2006:

– Applies to IGCC combustion turbines that burn

≥

75% “synthetic coal gas”

– When burning <75% syngas (12-month rolling

average), Subpart KKKK applies

•

This could be a problem during initial start-up

•

Meeting the NSPS for NOx may not be possible when burning
natural gas in diffusion burners designed for syngas

– Industry requested modification to regulations

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CoalFleet Program Update and Workshops

Kingsport, TN

July 26–28, 2005

New Source Performance Standards

•

EPA proposed changes in February 2007

•

IGCC is only covered by subpart Da, if:

–

“

The combined cycle gas turbine is

designed and

intended

to burn fuels containing 50 percent (by heat

input) or more solid-derived fuel not meeting the

definition of natural gas on a 12-month rolling

average basis; and

–

The combined cycle gas turbine commenced

construction, modification, or reconstruction after

February 28, 2005.”

New Source Performance Standards

•

Coal-fired electric utility steam generating unit

means an electric utility steam generating unit

that burns coal, coal refuse, or a

synthetic gas

derived from coal either exclusively, in any

combination together, or in any combination with

other fuels in any amount.

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CoalFleet Program Update and Workshops

Kingsport, TN

July 26–28, 2005

New Source Performance Standards

•

Integrated gasification combined cycle electric

utility steam generating unit

IGCC

means a

coal-fired electric utility steam generating unit

that burns a

synthetic gas

derived from coal in a

combined-cycle gas turbine. No coal is directly

burned in the unit during operation.

Air Permitting Requirements

• IGCC and PC plants are similar

– Fugitive dust controls

•

Coal delivery, unloading and handling

– Cooling towers

•

But IGCC cooling towers would have

lower duty since only 40% of plant

output is from steam turbine generator

– Air dispersion modeling

– BACT analysis for emission controls

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CoalFleet Program Update and Workshops

Kingsport, TN

July 26–28, 2005

Air Permitting: IGCC

• Unique emission points depend on technology

provider

– Flare

– Start-up burner

– Gasifier pre-heat burner

– Sulfur Recovery Unit tail gas incinerator

– Sulfuric Acid Plant stack

– Tank vents

– Air Separation Unit cooling tower

Air Permitting: IGCC

• For air permit application:

– Inventory of emission points has to be developed

early in the engineering process

– Emission limits in lb/hr are easier for measurement

and compliance than ppm or lb/MMBtu

– Startup, shutdown and emergency emissions must be

calculated – and can be substantial

– Emissions from flare are critical

•  Raw syngas
•  Clean syngas
•  Duration
•  Number of flare events/year

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CoalFleet Program Update and Workshops

Kingsport, TN

July 26–28, 2005

• Technical issues

–

The fuel is syngas, not natural gas as in NGCC

–

Ammonium sulfate/bisulfate deposits in the HRSG,
causing corrosion and plugging, requiring more
downtime for washdowns

–

Possible poisoning of SCR catalyst from syngas

–

No coal-based IGCC system in the world uses SCR

• Economic Issues

–

No commercial guarantees yet with syngas

–

SCR would require deeper sulfur removal to reduce
sulfate formation to low levels

• Selexol
•

Higher capital costs

SCR in a PC Plant

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What About SCR for IGCC?

CoalFleet Program Update and Workshops

Kingsport, TN

July 26–28, 2005

SCR: PC vs IGCC

•

FGD system, or baghouse

SCR in a PC plant

– Air pre-heater baskets:

have large openings due to
the fly ash in the exhaust gas
stream

are designed for removal,
replacement and cleaning

– Particulates are removed

downstream in the ESP,

SCR: PC vs IGCC

• SCR in an IGCC plant

– heat transfer occurs in the HRSG

•

on fixed finned tubing with small
clearances

•

designed for exhaust gas from
natural gas combustion – no
sulfates/bisulfates

•

sulfate/bisulfate deposition would be
a problem on finned tubing

•

finned tubing is not designed for
removal, replacement or easy
cleaning

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CoalFleet Program Update and Workshops

Kingsport, TN

July 26–28, 2005

Why SCR?

• But more IGCC plants are being proposed with

SCR than without SCR

• Reasons:

– As BACT
– As Innovative Control Technology to reduce

emissions beyond diluent injection

– As a trial/experiment, with emission limits proposed

only for natural gas use

– To evaluate SCR as part of DOE demonstration

program with a syngas-fired combined cycle unit

– To minimize NOx emissions in order to reduce NOx

emission allowance costs

NOx BACT

using SCR w/IGCC

sulfur removal

–

issue

• EPA has addressed this issue

• Report notes technical problems with

• Looked at SCR w/Selexol for deep

• EPA concluded that:

even w/Selexol, problems are not solved

additional cost and reduced output are
negative impacts to IGCC

BACT will continue to be a case-by-case

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CoalFleet Program Update and Workshops

Kingsport, TN

July 26–28, 2005

Mercury Removal: PC

•

Inject activated carbon in flue gas stream

Mercury adsorbed onto carbon particle

Particles removed in ESP or baghouse

Mercury Removal: IGCC

•

stream

•

once/year

•

this technology

Pre-sulfided carbon beds in syngas

Forms a mercury-sulfur complex

Spent carbon disposed of in drums

Most IGCC plants plan to use

Source: Eastman Chemical

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CoalFleet Program Update and Workshops

Kingsport, TN

July 26–28, 2005

NOx and SO

Emissions

• NOx emission rates not very different for

proposed PC and IGCC units

• IGCC units being proposed with much lower SO

emission rates

– due to ability to remove higher percentages of H

S vs

• Mercury emission rates about the same for PC

and IGCC

Air Emission Comparisons - NOx

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

NOx

Orlando Gasification IGCC w SCR PRB

Seminole Unit #3 SCPC - Bit. Coal/Pet
Coke

Taylor Energy Center SCPC - Bit. Coal Pet
Coke

Peabody Thoroughbred SCPC-Bit Coal

Excelsior Energy Mesaba IGCC - PRB

AEP GCC - Bit. Coa

Duke Edw ardsport GCC - Bit. Coa

FPL Glades USC - Bit Coal Pet Coke

TXU SCPC - PRB

ERORA IGCC w SCR - B t. Coa

Tondu Nue ce s GCC w SCR - Pe t Coke

Energy Northwest IGCC w SCR PRB or Pet
Coke

Lb/M

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CoalFleet Program Update and Workshops

Kingsport, TN

July 26–28, 2005

Air Emission Comparisons – SO

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

SO2

Orlando Gasification IGCC PRB

Seminole Unit #3 SCPC - Bit. Coal/Pet Coke

Taylor Energy Center SCPC- Bit Coal Pet
Coke

Peabody Thoroughbred SCPC Bit Coal

Excelsior Energy Mesaba IGCC - PRB

AEP IGCC - Bit. Coal

Duke Edw a rdsport GCC - Bit. Coa

FPL G a de s USC - B t. Coa Pe t Coke

TXU SCPC - PRB

ERORA IGCC w SCR - Bit. Coa

Tondu Nueces IGCC - Pet Coke

Energy Northwest IGCC- PRB or Pet Coke

Lb/M

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