How is the dry flue gas desulfurization process in a medium-temperature circulating fluidized bed?

The dry flue gas desulfurization process in a medium-temperature circulating fluidized bed is a typical gas-solid reaction process. The flue gas enters the circulating fluidized bed through a distribution plate and first comes into contact with the bed material in the dense phase layer; most of the material in this dense phase layer consists of desulfurization products that have reacted to a certain extent, as well as the desulfurizing agents that have just been added. In the flue gas, SO2 undergoes both physical and chemical adsorption on the materials in the bed – SO2 diffuses from the surface into the interior of the desulfurizing agents, where the desulfurization reaction takes place. As the flue gas rises, both the concentration of SO2 and that of the bed material decrease. The SO2 in the flue gas continues to react with the active components present in the bed material it carries. Due to the characteristics of the circulating bed, some of the bed material aggregates and falls back, coming into contact with the flue gas in the reverse flow direction. As the desulfurization reaction proceeds, the concentration of SO2 decreases, and the reaction rate slows down. The flue gas then passes through the bed outlet and enters a cyclone separator for gas-solid separation; subsequently, the flue gas along with the bed material it contains goes into a bag filter, where the extremely fine particles are captured, and the flue gas leaves the system.