Flue Gas Desulfurization

The best demonstrated available technology for reducing SO₂ emissions is Flue Gas Desulfurization (FGD) systems. These systems are designed to introduce an alkaline sorbent consisting of lime or limestone (primarily limestone) in a spray form into the exhaust gas system of a coal-fired boiler. The alkali reacts with the SO₂ gas and is collected in a liquid form as calcium sulfite or calcium sulfate slurry. The calcium sulfite or sulfate is allowed to settle out as most of the water is recycled.