Flue gas desulfurization (FGD) is a technology used to remove sulfur dioxide (SO2) from the exhaust flue gases of fossil fuel power plants. Fossil fuel power plants burn coal or oil to produce steam for steam turbines, which in turn drive electricity generators.
Sulfur dioxide is one of the elements forming acid rain. Tall flue gas stacks disperse emissions by diluting the pollutants in ambient air and transporting them to other regions.
As stringent environmental regulations regarding SO2 emissions have been enacted in many countries, SO2 is now being removed from flue gases by a variety of methods. The below is among the common methods used:
Wet scrubbing using a slurry of alkaline sorbent, usually limestone or lime, or seawater to scrub gases;
Spray-dry scrubbing using similar sorbent slurries;
Wet sulfuric acid process recovering sulfur in the form of commercial quality sulfuric acid;
SNOX Flue gas desulfurization removes sulfur dioxide, nitrogen oxides and particulates from flue gases;
Dry sorbent injection systems.
For a typical coal-fired power station, FGD will remove 95 percent or more of the SO2 in the flue gases.