Sulfur Dioxide Scrubbers
Flue gas desulfurization (FGD) technology, commonly referred to as a scrubber, is a proven and effective method for removing sulfur dioxide (SO2) emissions from the exhaust of coal-fired power plants.
How does a scrubber work?
During the combustion process the sulfur that is present naturally in the coal combines with the oxygen in the combustion air to form SO2. The SO2 is captured by bubbling the exhaust gas through a mixture of lime or limestone and water. This mixture reacts with the SO2 to remove it before the exhaust gas is released to the atmosphere. Duke Energy’s scrubbers are typically designed to remove 95 percent or more of the SO2 that is contained in the exhaust gas. The white plume that comes out of the stack is water vapor.
Why reduce SO2 emissions?
Sulfur dioxide emissions from power plants undergo complex reactions in the atmosphere to form fine particles. These fine particles are referred to as secondary particles because they aren’t emitted directly into the atmosphere. Emissions from industrial sources and automobiles also contribute to the formation of secondary particles.
What happens to the SO2 that is captured in a scrubber?
The SO2 that is captured in a scrubber combines with the lime or limestone to form a number of byproducts. A primary byproduct is calcium sulfate, commonly known as synthetic gypsum. It is a recyclable product and has many beneficial uses. Synthetic gypsum is the primary ingredient in the manufacture of wallboard. It is also used as a soil amendment in agricultural and construction applications, and in the manufacturing of cement. Much of the synthetic gypsum that is produced from Duke Energy’s scrubbers is reused in these and other applications. The scrubber byproducts that are not reused are disposed of in permitted landfills.