Process Description of Limestone based Wet Flue Gas Desulphurization System

  • The incoming flue gas from boiler after ESP / Bag Filter is brought into contact with aqueous slurry of limestone in a scrubber tower.
  • Sulphur dioxide in the gas reacts with the slurry to form calcium sulphite which is oxidized in oxidation tank to produce Gypsum.
  • Gypsum is continuously removed from the oxidation tank in the form of slurry.
  • This slurry is passed through hydro cyclones followed by a filtration plant to separate gypsum flakes (10 -15 % moisture) and filtrate is recycled back to the process.


  • Low Cost Limestone is used as sorbent
  • Commercial grade Gypsum is obtained as by-product
  • Most proven technology worldwide
  • Reasonable Operating cost
  • By-product (gypsum) is sellable
  • No disposal cost
  • High SO2 removal efficiency
  • Negligible liquid effluent discharge from the plant.
  • No solid waste is generated


  • Coal fired power plants
  • Large process boilers
  • Carbon black plants