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Here's how a typical SO2 scrubber works:

1.Flue Gas Inlet: The scrubbing process begins with the introduction of the flue gas containing sulfur dioxide into the scrubber system.
2.Absorption: In the scrubber, the flue gas is exposed to a liquid absorbent, which is usually a calcium-based slurry or solution. The most common absorbent is limestone (calcium carbonate), but other materials like lime (calcium oxide) or magnesium-based compounds can also be used.
3.Chemical Reaction: Sulfur dioxide in the flue gas reacts with the calcium-based absorbent to form calcium sulfite or calcium sulfate, depending on the specific chemistry employed. The chemical reaction is as follows:
For calcium carbonate (limestone):
SO2 + CaCO3 + 1/2O2 → CaSO4 + CO2
4.Neutralization: The calcium sulfite or calcium sulfate is removed from the scrubber system, leaving the exhaust gas cleaned of most of its sulfur dioxide content.
5.By product Handling: The byproducts of the scrubbing process (usually calcium sulfate, often referred to as "FGD gypsum") can be collected and may have commercial value. FGD gypsum can be used in various applications, including in the production of construction materials.
6.Clean Gas Outlet: The treated flue gas, now with significantly reduced SO2 levels, is released into the atmosphere, complying with environmental regulations.

SO2 scrubbers are a crucial component of environmental protection efforts to reduce sulfur dioxide emissions and mitigate their environmental and health impacts. They play a vital role in achieving compliance with air quality standards and reducing acid rain, which can have harmful effects on ecosystems and infrastructure. Different types of SO2 scrubbers, such as wet scrubbers, dry scrubbers, and semi-dry scrubbers, exist, each with its own advantages and disadvantages, depending on the specific application and regulatory requirements.