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Flue Gas Desulphurization

Topics Covered: Conservation, environmental pollution and degradation, environmental impact assessment.

Flue Gas Desulphurization:


The Ministry of Power has proposed pushing back deadlines for adoption of new emission norms by coal fired power plants, saying “an unworkable time schedule” would burden utilities and lead to an increase in power tariffs.


  • The Centre had initially set a 2017 deadline for thermal power plants to comply with emissions standards for installing Flue Gas Desulphurization (FGD) units that cut emissions of toxic sulphur dioxide.
  • That was later changed to varying deadlines for different regions ending in 2022. Under the latest proposal, no new dates have been set.
  • The target should be to maintain uniform ambient air quality across the country and not uniform emission norms for thermal power plants.

What is flue gas desulphurisation?

  • Removal of Sulfur Dioxide is called as Flue-gas Desulphurization (FGD).
  • It seeks to remove gaseous pollutants viz. SO2 from exhaust flue gases generated in furnaces,boilers, and other industrial processes due to thermal processing, treatment, and combustion.

Common methods used:

  1. Wet scrubbing using a slurry of alkaline sorbent, usually limestone or lime, or seawater to scrub gases;
  2. Spray-dry scrubbing using similar sorbent slurries;
  3. Wet sulfuric acid process recovering sulfur in the form of commercial quality sulfuric acid;
  4. SNOX Flue gas desulfurization removes sulfur dioxide, nitrogen oxides and particulates from flue gases;
  5. Dry sorbent injection systems that introduce powdered hydrated lime (or other sorbent material) into exhaust ducts to eliminate SO2 and SO3 from process emissions.


Prelims Link:

  1. What is flue gas desulphurisation?
  2. Methods.
  3. What is SO2? How is it produced?

Sources: the Hindu.