The Flue Gas Desulfurization (FGD) process is a critical technology used to remove sulfur dioxide (SO₂) from exhaust flue gases generated by fossil fuel power plants, industrial boilers, and other combustion processes. Among the various FGD methods, the limestone-gypsum wet flue gas desulfurization system is one of the most widely adopted due to its high efficiency, reliability, and ability to produce valuable by-products such as gypsum.In this system, limestone (calcium carbonate, CaCO₃) is used as the primary reagent to absorb SO₂ from the flue gas. The process begins with the flue gas being introduced into an absorber tower, where it comes into contact with a limestone slurry. The SO₂ in the flue gas reacts with the limestone slurry to form calcium sulfite (CaSO₃). To enhance the efficiency of the reaction, air is introduced into the system, oxidizing the calcium sulfite into calcium sulfate (CaSO₄), commonly known as gypsum. The chemical reactions involved in this process are as follows:1. Absorption: SO₂ + CaCO₃ + ½O₂ + 2H₂O → CaSO₄·2H₂O + CO₂ 2. Oxidation: CaSO₃ + ½O₂ → CaSO₄ The gypsum slurry produced in the absorber tower is then sent to a hydrocyclone for separation. The hydrocyclone is a key component in the system, as it efficiently separates the gypsum particles from the slurry based on their size and density. The separated gypsum is further dewatered and processed to produce high-purity gypsum, which can be used in various applications, such as construction materials (e.g., wallboard) or as a soil amendment in agriculture. The remaining liquid, which contains unreacted limestone and other impurities, is recycled back into the absorber tower to maximize reagent utilization and minimize waste.One of the significant advantages of the limestone-gypsum wet FGD system is its ability to achieve high SO₂ removal efficiencies, often exceeding 95%. Additionally, the system is highly adaptable and can handle varying flue gas compositions and flow rates. The use of limestone as a reagent is cost-effective, as it is widely available and relatively inexpensive. Furthermore, the production of gypsum as a by-product adds economic value to the process, making it an environmentally and economically sustainable solution.In summary, the limestone-gypsum wet flue gas desulfurization system, combined with hydrocyclone separation, is a highly effective and efficient method for reducing SO₂ emissions from industrial processes. Its ability to produce valuable by-products, coupled with its high removal efficiency and operational flexibility, makes it a preferred choice for flue gas desulfurization in various industries.