Traditional and Emerging

Air Pollutant Control for

Baseload Generation Stations

Greg Owen

2

Topics Covered

• What are air pollutants?

• Why are they important to

understand?

• How are air pollutants controlled?

• What’s ahead for the future?

3

Quiz Question #1

• Which of the following is used to

remove particulate matter?

A. Wet Scrubber

B. Baghouse

C. Over-Fire Air

4

Quiz Question #2

• Which of the following is used to

remove sulfur-based pollutants?

A. Dry Scrubber

B. Electrostatic Precipitator

C. Selective Non-Catalytic Reduction

5

Quiz Question #3

• Which of the following is used to

remove nitrogen-based pollutants?

A. Wet Scrubber

B. Fabric Filter

C. Selective Catalytic Reduction

6

Basin Electric Power

Cooperative

• 138 Member Cooperatives

• 540,000 square miles

• 9 states • 2.9 million

consumers • Operate 5,003

MW generation • 5,594 MW

generation portfolio

• Owns/maintains >2,000 miles of HV transmission

LRS

DFS

AVS LOS

DCS

7

Air Pollutants Definition

• Air pollutants are any physical,

chemical, biological, radioactive

substance or matter which is emitted

into or otherwise enters the ambient air

• Principle Air Pollutants – Carbon Monoxide

– Lead

– Nitrogen Dioxide

– Ozone

– Sulfur Dioxide

– Particulate Matter (2.5 and 10 µm)

• Limits vary per location

• Newer plants have more restrictive limits

• Plants must meet all limits

8

Timeline of Legislation

1963 1970 1990 2011 2015

Clean Air Act passed by Congress

Clean Air Act amended, includes National Ambient Air Quality Standards

Clean Air Act amended, includes Acid Rain program and Maximum Achievable Control Technology

Mercury and Air Toxics Standards

Clean Power Plan becomes law

9

Current and Proposed Air

Rules

• State Air Rules (typically follow EPA rules)

• Clean Air Act

• Acid Rain Program

• New Source Performance Standards (NSPS)

• Mercury and Air Toxics Standards (MATS)

• New Source Review (NSR)

• Toxic Release Inventory (TRI)

• Clean Power Plan (Green House Gases)

• State Radiation Rules

10

How Do We Demonstrate

Compliance With Each Limit?

• Calculate emissions using engineering

data such as: air flow, fuel feed rate,

heat rate, and a derived or measured

emission factor.

• Install a continuous emission

monitoring system, CEMS

11

Non-compliance Penalties

• States

– Notice of Violation for state rules

– Typically try to get source back into compliance without taking legal action

– Fines up to $25k/day possible

• Federal

– More likely to see penalty

– Lawsuits from environmental groups

– Courts can issue corrective action

Traditional Air Pollutant Control

13

Particulate Matter Control

Electrostatic Precipitator LRS

• Approximately 100’ long, 100’ tall, 55’ wide

• Four per unit in parallel

• 40 transformer/rectifiers • 55kV DC • ~4MW load

14

Laramie River Station Precip

Electrodes and Plates Mechanical Rapper

15

Particulate Control -

Fabric Filter/Baghouse AVS

28 compartments with 288 bags each Total of 8,064 bags per unit

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Particulate Control -

AVS Baghouse

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Other Particulate Control

• Bottom Ash Handling

• Dust Collectors

• Stack

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Sulfur Control

• Chemical reaction to reduce SO2

compounds

• Typical reagents:

– Limestone (Calcium Carbonate)

– Lime (Calcium Oxide or Calcium

Hydroxide)

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Sulfur Control - Wet Scrubber

Flue Gas Desulfurization LRS

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Wet Scrubber LRS

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Sulfur Control - “Dry” Scrubber

AVS Spray Dryer Absorber

22

Dry Scrubber AVS

23

Sulfur Control - DFS

Circulating Fluidized Bed

Scrubber

See Power Engineering Magazine, September 2015, Vol. 119, No. 9, pg 18-23

24

Circulating Fluidized Bed

Scrubber DFS

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Nitrogen Control

• Sources: Fuel and Air

• Rapid formation >2800 degF

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Nitrogen Control - Over Fire Air

Low NOx Burners

Over-fire air ports

Low NOx burners

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Nitrogen Control - Over Fire Air

Low NOx Burners for LRS

1980-1982

1995 2009-2011

2012-2015 1996

Station began operating, 0.7 lbs/MBtu

Replaced burner nozzles, $300k/unit 0.3 lbs/MBtu

Added over-fire air, $7.5M/unit 0.19 lbs/MBtu

New Low-NOx burners & more OFA $19M/unit 0.15 lbs/MBtu

Operational adjustments $0 0.27 lbs/MBtu

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Nitrogen Control - Combustion

Optimization

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Nitrogen Control - Selective

Non-Catalytic Reduction (SNCR)

• Inject reagent (NH3) directly into furnace

• High temperatures (1600-2100 deg F)

• Process intensive

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Nitrogen Control - Selective

Catalytic Reduction (SCR)

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Selective Catalytic Reduction

DFS

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Selective Catalytic Reduction

LRS

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Selective Catalytic Reduction

LRS

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Mercury Control

• Activated Carbon Injection

35

Best Available Retrofit

Technology

1. Identify all available technologies

2. Eliminate technically infeasible options

3. Evaluate control effectiveness for each remaining control technology

4. Evaluate impacts and document results

5. Evaluate visibility results

6. Select BART

Emerging Pollutant Control

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Nitrogen Control

• Pulsed Beam

• NOx bonds

are broken,

forming O2

and N2

• Process still

being refined

See Power Engineering Magazine, February 2015

38

Clean Power Plan

• Proposed in June 2014

• Final version unveiled 8/3/15,

published 10/23/15, effective 12/22/15

• Over 3,000 pages

• 32% nationwide reduction in CO2

• Compliance plans by 2018

• Full compliance by 2030

• About 2 dozen states planning litigation

39

Clean Power Plan

40

Clean Power Plan

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Carbon Control Methods

• North Dakota Energy & Environmental Research Center – www.undeerc.org

• Pre-combustion – Oxy fuel

• Post-combustion – Boundary Dam

• Chemical looping

• Allam Cycle

• Clean Power Plan

– Improve efficiency

– Use Natural Gas

– Renewable

Energy

– Carbon Credits

• Carbon Capture

– DGC > 30M tons

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Allam Cycle Using Natural Gas

Zeus Combustor

Heat Exchanger

Turbine

Pump

Generator

CO2 and Water

CO2 to Pipeline

O2 ASU

N2

Air

NG from Pipeline

Water Separator

Recycle CO2

Water

43

Quiz Question #1

• Which of the following is used to

remove particulate matter?

A. Wet Scrubber

B. Baghouse

C. Over-Fire Air

44

Quiz Question #2

• Which of the following is used to

remove sulfur-based pollutants?

A. Dry Scrubber

B. Electrostatic Precipitator

C. Selective Non-Catalytic Reduction

45

Quiz Question #3

• Which of the following is used to

remove nitrogen-based pollutants?

A. Wet Scrubber

B. Fabric Filter

C. Selective Catalytic Reduction

Questions?