Sulfur dioxide (SO2) is a pollutant often generated from combustion of fossil fuels. SO2 is a major contributor to air pollution, leading to the formation of acid rain, visibility obstruction and health problems. To combat this issue, Flue Gas Desulfurization (FGD) technologies are used in many power plants to reduce the amount of SO2 in the combustion flue gas stream.
FGD is an advanced method to clean up exhaust gases from coal- or oil-fired boilers. The process involves the reaction of SO2 with a sorbent to remove it from the flue gas. The sorbent is typically limestone, lime or other limestone derivatives such as calcium hydroxide. The flue gas is thoroughly mixed with the sorbent, and is then fed into a reactor where the sorbent reacts with the SO2. The reaction leads to the formation of a alkaline slurry which is then further processed.
After reaction in the absorber, the slurry is fed to a clarifier where the particles settle to the bottom, and are then removed by decantation. The clarified solution is then fed to a regeneration process, where the sulfur dioxide is converted to sulfuric acid, which can be sold as a by-product or reused within the plant.
In the regeneration process, the alkaline slurry is fed into a reactor, where it is heated and pressurized in a closed system. In the presence of a catalyst, the sulfur dioxide is converted to sulfuric acid, which can then be recovered as a by-product.
Furthermore, the remaining slurry from the regeneration process is sent to a second clarifier, where the remaining particles are removed. The clarified solution is then remixed with limestone or lime in a slurry tank, and is then returned to the absorber for reuse.
The use of FGD is an effective method for removal of SO2 from flue gas. The process is highly efficient, with a typical SO2 removal efficiency of 95-98 %, depending on the sorbent used, the flue gas temperature and moisture content, and the FGD system design. In addition, FGD systems are often designed to allow for flexibility in operation. This is important because the flue gas conditions can vary widely between different fuels, causing significant variation in the SO2 concentrations. The flexibility of the system allows for quick switching between different fuels.
In conclusion, FGD is an advanced technology which can be used to reduce SO2 emissions from combustion processes. The process is efficient and has the potential to achieve high SO2 removal rates with little environmental impact. Furthermore, the process is designed to be flexible, allowing it to respond to varying flue gas conditions and to accommodate a wide range of fuels.
