Chapter 12. Air Pollution Control

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Chapter 12. Air Pollution Control

• CIEG 331
• Introduction to Environmental Engineering

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Air Pollution Control

• Gaseous
• Particulates

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Gaseous Pollutants

• Absorption
• Adsorption
• Combustion

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Flue Gas Desulfurization (FGD)

• Non-regenerative non-recovery and reuse of
  chemical reagents
• Regenerative recovery and reuse of chemical
  reagents

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Non-regenerative systems

• Chemicals lime, limestone, caustic soda, soda
  ash, ammonia
• SO2 CaCO3 ---gt CaSO3 CO2
• SO2 Ca(OH)2 ---gt CaSO3 H2O
• CaSO3 1/2 O2 ---gt CaSO4
• Types
• Wet
• Dry

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Wet Type

• Venturi
• Static packed
• Moving bed
• Tray tower
• Spray towers

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Vertical Venturi Scrubber
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Packed Bed Scrubber
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Dry Scrubber System
http//www.fkinc.com/dirctspraydry.htmtop
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Control Technologies for Nitrogen Oxides

• Preventive
• minimizing operating temperature
• fuel switching
• low excess air
• flue gas recirculation
• lean combustion
• staged combustion
• low Nox burners
• secondary combustion
• water/steam injection

• Post combustion
• selective catalytic reduction
• selective non-catalytic reduction
• non-selective catalytic reduction

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Particulate Pollutants

• Cyclone
• Filter
• Liquid scrubbing
• Electrostatic precipitation (ESP)

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Cyclone
d0.5 cut diameter at 50 removal m dynamic
viscosity of gas, Pa-s B width, m H height,
m rp particle density, kg/m3 Qg gas flow
rate, m3/s q effective number of turns
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For standard Cyclone B 0.25 D2 0.13 m H
0.5 D2 0.25 m L1 L2 2 D2 1 m
Ex. 6-9 Given D2 0.5 m Qg 4 m3/s T 25
oC rp 800 kg/m3
Q What is the removal efficiency for
particles with ave diameter of 10 mm?
h 0.95
_at_ d 10 mm
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Cyclone Installation at Wood Working Plant
http//www.fkinc.com/cyclones.htm
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Air Filtration
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Case A Pore blocking Case B Pore plugging Case
C1 Pore narrowing Case C2 Pore narrowing
w/lost pore Case D Pore bridging
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Air Filtration

• Impaction
• Diffusion
• Straining (Interception)
• Electrostatics

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Air Filter

• High removal efficiency for lt 5 mm particles

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Scrubber

• Venturi

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ESP
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ESP
http//www.powerspancorp.com/news/precipitator.sht
ml
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http//www.ppcbio.com/ppcdespwhatis.htm
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