Process Description of Furnace Sorbent Injection based Dry Flue Gas Desulphurization System

  • Lime stone or lime is injected into the combustion furnace and /or in the convection zone of the boiler for SO2 absorption.
  • Lime or limestone reacts with SO2 forming calcium sulphite, CaSO3, which partially oxidizes to anhydrous calcium sulphate, CaSO4.
  • The solid by-products are then collected at the bottom of the furnace as well as in the electro static precipitator /fabric filter.


  • Dry Lime /limestone powder used as sorbent
  • Upto 90% SO2 removal is possible
  • Integrated SO2 and particulate control
  • Low initial cost
  • Low operating cost
  • Well suited to a situation where only a low SO2 removal efficiency is required, and where there is little space available in the unit plant area
  • The by-products have no reuse potential. Landfill is the only option.
  • Excess lime / limestone dosing is needed due to very small time available for reaction in the furnace.


  • Even though this process has been widely used for large boiler upto 50 MWe, it is recommended only for CFBC boiler applications with sulfur content in fuel not exceeding 1%