FlueGas Desulfurization (FGD) is the main measure for controlling sulfur dioxide emissions in coal-fired systems today. Limestone gypsum wet flue gas desulfurization is a widely used and mature process in various countries around the world.

There are many types of valves used in FGD systems. Due to the fact that pipelines in desulfurization engineering often come into contact with harsh media, scaling, blockage, corrosion, and wear are common problems in FGD systems, which seriously affect the equipment operation rate of the system. Therefore, the correct selection of valves also requires understanding the properties of the medium they come into contact with.

The FGD slurry system is divided into three major parts based on the composition of the medium: limestone slurry, limestone gypsum slurry, and gypsum slurry. Its main characteristics are as follows:

(1) Granular, with wear resistance, the mass fraction of limestone slurry can reach 55%, and the density can reach 1500kg/m3;

(2) PH=4-7, inorganic chemical weak acid corrosion;

(3) Organic solutions containing inert substances with corrosive properties;

(4) The flow rate is fast, and in general, the slurry flow rate is controlled below 2.5m/s in design. In actual operation, it can reach up to 3.5m/s, with particle jet phenomenon. The circulating water and process water can reach up to 5m/s;

(5) High Cl - concentration: Desulfurization engineering companies generally design at 20000mg/L, with actual tower concentrations reaching around 180000mg/L, and wastewater containing around 40000 mg/L. In addition to acidic corrosion, it also has strong oxidizing and reducing properties. Overall, limestone slurry exhibits more severe abrasion, while gypsum slurry exhibits more corrosiveness.

Therefore, for valve selection, in addition to conventional requirements such as excellent product design, low torque, flexible action, reliable operation, long service life, and low maintenance costs, wear resistance and corrosion resistance are also required.