title page · generalized wesp process description conditioning section • ensures gas is...
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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
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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
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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)
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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
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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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