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Air Pollution
Control Measures:
Air pollution occurs when the air contains
gases, dust, fumes or odour in harmful
amounts.
The substances that cause air p...
5 Major Pollutants:
1.) Carbon Monoxide
2.) Sulfur Dioxide
3.) Nitrogen Dioxide
4.) Particulate Matter
5.) Ground Level Oz...
The atmosphere has several built-in self cleaning
processes such as dispersion, gravitational
settling, absorption, rain-w...
 To be able to identify and describe the
different air pollution control devices which
are used by different industries.
...
Flue-gas
desulfurization (FGD):
 Flue gas is the gas
exiting to the
atmosphere via a flue,
which is a pipe or
channel for...
Flue-gas desulfurization (FGD)
is a set of technologies used to
remove sulfur dioxide (SO2)
from exhaust flue gases of fos...
It is a control
device that
absorbs and
react using
the alkaline
reagent to
produce a
solid
compound.
The largest part of the flue gases from most fossil
fuel combustion are..
Uncombusted Nitrogen
Carbon Dioxide (CO2)
Wat...
Flue-gas
desulfurization (FGD):
Mechanism of Pollutant Removal
How does it work?
•Wet scrubbing using a slurry of alkaline...
oWet sulphuric acid process recovering sulfur in
the form of commercial quality sulphuric acid.
oSNOX Flue gas desulfuriza...
o Works via the contact of target compounds or
particulate matter with the scrubbing solution.
Solutions may simply be wat...
o Removal efficiency of pollutants is improved
by increasing residence time in the scrubber or by
the increase of surface ...
Fig.1 wet scrubber
Scrubber: a device that removes impurities from gases.
Slurry: flowable suspension of small particles i...
Dry scrubbing
No moisture is added, while in others only the
amount of moisture that can be evaporated in the
flue gas wit...
Dry scrubbing systems
 Often used for the removal of odorous and
corrosive gases from wastewater treatment
plant operatio...
Wide range of removal for other odorous compounds
such as methyl mercaptans, aldehydes, volatile organic
compounds, dimeth...
Dry sorbent injection
 Involves the addition of
an alkaline material (usually hydrated
lime or soda ash) into the gas str...
These devices have been used on medical waste incinerators
and a few municipal waste combustors.
Spray Dryer Absorbers
•The flue gases are introduced into an absorbing tower
(dryer) where the gases are contacted with a ...
These devices have been used on industrial and
utility boilers and municipal waste incinerators.
Absorber
The flue gas is passed
through a cartridge which is
filled with one or several
absorber materials and has
been ad...
MercuryRemoval
 Usually addition of the halogens to the flue gas are
used for this purpose. The type of coal burned as we...
 Mercury is a highly toxic element
commonly found in coal and municipal
waste. Wet scrubbers are only effective for
remov...
System Description
The equipment necessary for SO2 emission reduction
comes under four operations:
• Scrubbing or absorpti...
•Sludge processing - Accomplished with sludge clarifiers for
dewatering, sludge
pumps and handling equipment, and sludge s...
Flue-gas desulfurization (FGD): Advantages
•High SO2 removal efficiencies, from 50% up to 98%
•Products of reaction may be...
Flue-gas desulfurization (FGD): Disadvantages:
High capital and O&M cost
Scaling and deposit of wet solids on absorber a...
Flue gas desulphurization detailed process
Flue gas desulphurization detailed process
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Flue gas desulphurization detailed process

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Flue gas desulphurization detailed process

  1. 1. Air Pollution Control Measures:
  2. 2. Air pollution occurs when the air contains gases, dust, fumes or odour in harmful amounts. The substances that cause air pollution are called pollutants.
  3. 3. 5 Major Pollutants: 1.) Carbon Monoxide 2.) Sulfur Dioxide 3.) Nitrogen Dioxide 4.) Particulate Matter 5.) Ground Level Ozone
  4. 4. The atmosphere has several built-in self cleaning processes such as dispersion, gravitational settling, absorption, rain-washout, etc to cleanse the atmosphere. However, control of contaminants at their source level is a desirable and effective method through preventive or control technologies.
  5. 5.  To be able to identify and describe the different air pollution control devices which are used by different industries. Flue-gas Desulfurization To determine the effectiveness of this devices in controlling pollution. To familiarize with the mechanisms or processes on how this modern technologies work. Objectives:
  6. 6. Flue-gas desulfurization (FGD):  Flue gas is the gas exiting to the atmosphere via a flue, which is a pipe or channel for conveying exhaust gases from a fireplace, oven, furnace, boiler or steam generator
  7. 7. Flue-gas desulfurization (FGD) is a set of technologies used to remove sulfur dioxide (SO2) from exhaust flue gases of fossil- fuel power plants, and from the emissions of other sulphur oxide emitting processes.
  8. 8. It is a control device that absorbs and react using the alkaline reagent to produce a solid compound.
  9. 9. The largest part of the flue gases from most fossil fuel combustion are.. Uncombusted Nitrogen Carbon Dioxide (CO2) Water Vapor (H20) Nitrogen Oxides (NOx) Sulfur Dioxide (SO2) Particulate Matter
  10. 10. Flue-gas desulfurization (FGD): Mechanism of Pollutant Removal How does it work? •Wet scrubbing using a slurry of alkaline sorbent, usually limestone or lime, or seawater to scrub gases. •Spray-dry scrubbing using similar sorbent slurries.
  11. 11. oWet sulphuric acid process recovering sulfur in the form of commercial quality sulphuric acid. oSNOX Flue gas desulfurization removes sulfur dioxide, nitrogen oxides and particulates from flue gases. oDry sorbent injection systems.
  12. 12. o Works via the contact of target compounds or particulate matter with the scrubbing solution. Solutions may simply be water (for dust) or solutions of reagents that specifically target certain compounds. o A wet scrubber is used to clean air, fuel gas or other gases of various pollutants and dust particles. Wet scrubbing
  13. 13. o Removal efficiency of pollutants is improved by increasing residence time in the scrubber or by the increase of surface area of the scrubber solution by the use of a spray nozzle, packed towers or an aspirator. o Wet scrubbers may increase the proportion of water in the gas, resulting in a visible stack plume, if the gas is sent to a stack.
  14. 14. Fig.1 wet scrubber Scrubber: a device that removes impurities from gases. Slurry: flowable suspension of small particles in liquid.
  15. 15. Dry scrubbing No moisture is added, while in others only the amount of moisture that can be evaporated in the flue gas without condensing is added. Therefore, dry scrubbers generally do not have a stack steam plume or wastewater handling/disposal requirements. Dry scrubbing systems are used to remove acid gases (such as SO2 and HCl) primarily from combustion sources.
  16. 16. Dry scrubbing systems  Often used for the removal of odorous and corrosive gases from wastewater treatment plant operations.  The medium used is typically an activated alumina compound impregnated with materials to handle specific gases such as hydrogen sulfide.
  17. 17. Wide range of removal for other odorous compounds such as methyl mercaptans, aldehydes, volatile organic compounds, dimethyl sulfide, and dimethyl disulfide.
  18. 18. Dry sorbent injection  Involves the addition of an alkaline material (usually hydrated lime or soda ash) into the gas stream to react with the acid gases.  The acid gases react with the alkaline sorbents to form solid salts which are removed in the particulate control device. These simple systems can achieve only limited acid gas (SO2 and HCl) removal efficiencies.
  19. 19. These devices have been used on medical waste incinerators and a few municipal waste combustors.
  20. 20. Spray Dryer Absorbers •The flue gases are introduced into an absorbing tower (dryer) where the gases are contacted with a finely atomized alkaline slurry. Acid gases are absorbed by the slurry mixture and react to form solid salts which are removed by the particulate control device. •The heat of the flue gas is used to evaporate all the water droplets, leaving a non-saturated flue gas to exit the absorber tower.
  21. 21. These devices have been used on industrial and utility boilers and municipal waste incinerators.
  22. 22. Absorber The flue gas is passed through a cartridge which is filled with one or several absorber materials and has been adapted to the chemical properties of the components to be removed. The absorber material has to be replaced after its surface is saturated.
  23. 23. MercuryRemoval  Usually addition of the halogens to the flue gas are used for this purpose. The type of coal burned as well as the presence of a selective catalytic reduction unit both affect the ratio of elemental to oxidized mercury in the flue gas and thus the degree to which the mercury is removed.
  24. 24.  Mercury is a highly toxic element commonly found in coal and municipal waste. Wet scrubbers are only effective for removal of soluble mercury species, such as oxidized mercury.
  25. 25. System Description The equipment necessary for SO2 emission reduction comes under four operations: • Scrubbing or absorption - Accomplished with scrubbers, holding tanks, liquidspray nozzles, and circulation pumps. • Lime handling and slurry preparation - Accomplished with lime unloading and storage equipment, lime processing and slurry preparation equipment.
  26. 26. •Sludge processing - Accomplished with sludge clarifiers for dewatering, sludge pumps and handling equipment, and sludge solidifying equipment. •Flue-gas handling - Accomplished with inlet and outlet ductwork, dampers, fans, and stack gas reheaters.
  27. 27. Flue-gas desulfurization (FGD): Advantages •High SO2 removal efficiencies, from 50% up to 98% •Products of reaction may be reusable •Difficulty to retrofit is moderate to low •Inexpensive and readily available reagents
  28. 28. Flue-gas desulfurization (FGD): Disadvantages: High capital and O&M cost Scaling and deposit of wet solids on absorber and downstream equipment Wet system generates a water waste product and may result in visible plume Cannot be used for waste gas SO2 concentrations greater than 2,000 ppm Disposal of waste products significantly increases O&M costs

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