Title Page

What are WESPs and RTOs? WESP: Wet Electrostatic

Precipitator –

A device for removing particulates and condensable gasses from an air stream by imparting a charge to the particulates and fluid droplets then electrostaticly attracting them to collection plates where they will be captured and washed away.

RTO: Regenerative Thermal Oxidizer –

A device that destroys hydrocarbon molecules in an air stream by heating the air stream and oxidizing the hydrocarbons turning them into carbon dioxide and water vapor. Heat from the oxidation reactions is recovered and returned to the reaction chamber for further oxidation reactions.

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Targeted Reductions

Arsenic

Cadmium

Lead

1,3 Butadiene

Nickel

3

4

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Generalized WESP Process DescriptionConditioning

Section• Ensures gas is

saturated

• Evenly distributes gas to collection section

• Sub-cools gas in condenser/absorber

• Neutralize acid gases

• Polish SO2 removal

Outlet Section• Supports high voltage

grid

• Air purge system to

clean high voltage

insulators

• Wash headers to

provide wet film for

PM removal

Collection Section• Collects and

removes particulate

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Conditioning Section

Section is filled with a

scrubber tower

packing material

A soda ash solution is

continuously

circulated

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Looking up into the Collection

Section (the Honey Comb)

Saw tooth emitter

discs provide the

corona

Particles and

ionized droplets

are deposited on

the hexagonal

collectors

8

WESP Uses a Corona Discharge to

Charge and Remove particlesCHARGING

Particles are given strong negative charge by an ionizing corona produced by high-voltage electrodes

COLLECTING

The electric field causes charged particles to migrate to the grounded tube walls where they accumulate

REMOVING

A falling water film inside the tubes removes collected material to a discharge drain

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Outlet Section: Charge is delivered to the array of electrodes

through the suspension bars at the top of the array

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0

100

200

300

400

500

600

700

WESP Stack Process Emissions (lbs/year)

3.59

1.22

0.808

8.58

614.95

Progression of Lead Emission Reductions

Nov-10 Nov-09 Jun-09 Nov-08 Baseline (Pre-WESP)

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0

10

20

30

40

50

60

70

80

90

100

WESP Stack Process Emissions (lbs/year)

2.89

1.59

4.56

8.67

96.01

Progression of Arsenic Emission Reductions

Nov-10 Nov-09 Jun-09 Nov-08 Baseline (Pre-WESP)

12

0

1

2

3

4

5

6

7

WESP Stack Process Emissions (lbs/year)

1.08

0.53

0.14

1.01

6.55

Progression of Cadmium Emission Reductions

Nov-10 Nov-09 Nov-09 Nov-08 Baseline (Pre-WESP)

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Levels of Regulation

National Ambient Air Quality Standard for Lead (Lead

NAAQS)

1.5 ug/m3 (current)

0.15 ug/m3 (adopted & beginning implementation)

National Emission Standards for Hazardous Air

Pollutants for Secondary Lead Smelters (Subpart X)

California-specific rules:

Rule 1420.1

Early implementation of new Lead NAAQS

Rule 1402

Health Risk Assessment and Reduction

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RTO – Regenerative Thermal

Oxidation

Thermal

Beds

Inlet

Blower

Exhaust Duct

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Regenerative Thermal Oxidizer

17

RTO Ceramic Bed

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1, 3-Butadiene Emissions Reduced 98.4% &

Benzene Emissions Reduced 94.6% by RTO

Post-Project

33.3

Pre-Project

2,024

Post-Project

89.8

Pre-Project

1,653

0

500

1,000

1,500

2,000

2,500

Comparison of Emissions Pre- and Post-RTO Installation

Emis

sio

ns

- P

ou

nd

s P

er Y

ear

1,3-ButadieneBenzene

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Questions

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