What is a benefit of adding crushed limestone during fluidized bed combustion?

Adding crushed limestone during fluidized bed combustion primarily serves to reduce the emission of sulfur dioxide (SO2). This is because limestone (calcium carbonate) reacts with sulfur dioxide produced during the combustion of sulfur-containing fuels, such as coal. When limestone is introduced into the combustion process, it undergoes a chemical reaction that produces calcium sulfite, which can later be oxidized to gypsum. This process effectively captures sulfur and minimizes its release into the atmosphere as SO2, which is a major contributor to air pollution and acid rain.

This method is particularly advantageous in fluidized bed combustion systems because the conditions in these systems allow for better mixing and contact between the limestone and flue gas, leading to more effective desulfurization. As a result, power plants utilizing this technology can comply with emission regulations and reduce their environmental impact. This impact highlights the importance of employing additives like crushed limestone in improving air quality while operating power generation systems.