1. Air Pollution Control: Stationary source
Ms Sherina

2. Air Pollution Control approaches
Gas
Particulate

3. Gas Control Technologies
Divided into 2 categories
Process gases
Volatilized organic compounds
Solvents
perchloroethylene
Fuel vapors
Propane, hexane
Organic chemicals
Acid gases
HCl, HNO3, H2SO4, SO2, NO2
Toluene, methanol
Combustion gases
CO, Sulfur dioxides, NOx, product of incomplete combustion

4. Gas Control Technologies
Absorbers
Adsorbers
Condenser

5. Absorbers
Absorption is a gas-liquid contacting process that uses the preferentially solubility of the pollutant gas for the liquid phase
Applications
Gas streams containing
Alcohols
Acids
Substituted aromatics
Aldehydes
esters

6. Adsorbers
Work with the principle of molecular or atomic interaction at the surface of a sorbent
Process is exothermic
Application- gas phase air pollutants
Composed of either natural or synthetic materials

7. Adsorbers Typical adsorbent materials Activated carbon
Activated alumina
Molecular sieves
Silica gels

9. Condensers
Operate by the removal of heat from the gas stream and provide a surface/medium for condensations from the gas phase to liquid to take place
Two types
Surface
Coolant does not come into contact with the vapors/liquid condensate
Contact
The coolant, vapors and condensate are all intimately mixed

10. Condensers Used in gas streams containing: Aldehydes Alcohols
Chlorinated compounds
Fuel vapors
Organic acids

11. Particulate control technologies
Mechanical collectors
Settling chambers
Cyclones
Fabric filters
Wet scrubbers
ESP

12. Wet scrubbers
Provide control for a wide range of particulate emissions
Used to control dry particulates in gas streams, equipped with a water spray system

13. Wet scrubbers
Device that remove pollutants from a furnace flue gas or from other gas streams
Applications:
Gas streams containing emissions of dusts, metals, sticky particulates, soluble organic compounds

14. Wet scrubbers Advantages Relatively small space requirements
Ability to collect gases as well as particulates
Ability to handle high temperature, high humidity gas streams
Minimal fire and explosion hazards
Can neutralize corrosive gases
Ability to achieve high collection efficiencies on fine particulates

15. Wet scrubbers Disadvantages Relatively high maintainance cost
Must be protected from freezing
Problem creation of water disposal problem
Product collected wet
Pressure drop and horsepower requirements possibly high

16. Dry scrubber
does not saturate the flue gas stream that is being treated with moisture
In some cases no moisture is added; while in other only the amount of moisture that can be evaporated in the flue gas without condensing is added
do generally not have wastewater handling/disposal requirements
Dry scrubbing systems are used to remove acid gases(such as SO2 and HCl) primarily from combustion sources

17. Dry scrubber Advantages No wet sludge to dispose of
Relatively small space requirements
Ability to collect acid gases at high efficiencies
Ability to handle high temperature gas streams

18. Dry scrubber
Acid gas control efficiency not as high as wet scrubber

19. END OF LECTURE