What is the purpose of adding lime (CaCO₃) to the bed in fluidized bed combustion?

The purpose of adding lime (CaCO₃) to the bed in fluidized bed combustion is primarily to reduce SO₂ emissions. When limestone is introduced into the combustion process, it undergoes a chemical reaction with sulfur dioxide (SO₂) produced during the combustion of sulfur-containing fuels, such as coal. The reaction forms calcium sulfite (CaSO₃), which can further oxidize to form calcium sulfate (CaSO₄). This process effectively captures sulfur emissions and helps in meeting environmental regulations regarding air quality.

By incorporating lime into the fluidized bed, operators can not only control sulfur emissions but also enhance the overall sustainability of the combustion process. This integrated approach plays a crucial role in minimizing the environmental impact of power generation facilities utilizing fossil fuels.