Flue Gas Desulphurisation (FGD) Technology

The Ministry of Power reviewed an IIT-Delhi study that challenged need for Flue Gas Desulphurisation in thermal power plants.

About FGD Technology:

• Flue Gas Desulphurisation technology is essential for removing Sulfur Dioxide (SO₂) from exhaust emissions.
• Burning fossil fuels like coal and oil produces flue gas with high SO₂ content.
• Approximately 95% of the sulfur in these fuels converts to SO₂ during combustion.
• The Ministry of Environment, Forest & Climate Change has mandated FGD systems for all coal-based TPPs. FGD technology is crucial for maintaining a clean and safe environment.
• There are three major types of FGD systems used globally:
  • Dry Sorbent Injection: Uses limestone to remove SO₂.
  • Wet Limestone Based: Utilizes a slurry of water and limestone.
  • Sea Water Based: Employs sea water for SO₂ removal.
• FGD systems are highly efficient, capable of removing over 90% of SO₂ from flue gas emissions.

FGD Process:

• The FGD process involves the use of absorbents to eliminate SO₂ from flue gas.
• Common absorbents include ammonia, sodium sulfite, lime, or limestone slurry.
• The process is typically carried out in a scrubber tower (absorber tower).
• The uncleaned flue gas is sprayed with a scrubbing slurry, a mixture of water and limestone.
• A chemical reaction occurs, bonding most of the SO₂, effectively removing up to 95% of the sulfur dioxide.

About SO₂:

• SO₂ is a toxic gas produced by burning fossil fuels containing sulfur.
• It is a major air pollutant affecting human health and the environment.
• It is a precursor to acid rain, which damages forests, freshwater, soils, insects, aquatic life, and man-made structures.

Environmental and Health Implications:

• Acid rain, resulting from SO₂, leads to the corrosion of steel structures such as bridges and the weathering of stone buildings and statues.

SO₂ is also detrimental to human health, primarily affecting the respiratory system