Air Pollution Control notes for B.Sc. Sem. IV Environmental Science of Gondwana University, Gadchiroli

1. Pollution Control Technologies
Air Pollution Control

2. Air pollution control
• Particulates
• Gaseous
– Mechanical devices
– Bag House filter/Fabric filter
– Electrostatic precipitator
– Wet scrubber

3. Particulate air pollution control
• Settling chambers
• Impact separators/Inertial
• Cyclones

4. Gravitational settling chamber
• Gas inlet speed
< 3 m/sec
• Best results
0.3 m/sec

5. Baffled chamber

7. Cyclone separators
• Centrifugal force
• Greater the centrifugal
force, the greater the
separating efficiency
• Efficiency 90%

8. Internal force in a cyclone separator

9. Bag house filter (Fabric filter)
• Fabric: cotton,
wool, nylon,
dacron,
polypropylene,
fabric glass
• Fabric bag: 2-10
m length, 12-40
cm dia.
• Inlet air: v=0.4-
1.0 m/min

12. Electrostatic precipitator

14. Scrubbers (Wet collectors)
• Devices utilize liquid
• Water is used as a scrubber
• Dust agglomerate with water
• Cheap to install
• Expensive to operate

15. • Steps involved:
Transportation
Collision
Adhesion
Precipitation
• Principles of scrubbers:
– Impingement (to strike)
– Interception (to stop)
– Diffusion (spreading out)
– Condensation

16. Spray towers Venturi scrubber

18. • Most frequently used
• High energy wet
scrubber
• Efficiency for removing
particulate matter
• Velocity= 60-100 m/sec

19. Cyclone spray scrubber

20. Flue gas desulfurization
• Flue gas has high % of SO2
• Coal having high sulphur content
• Reduction of SO2 in flue gases by
– By liquid ammonia
– Lime stone-lime wash method