Thread Content
For some large desulfurization towers in power plants, they are mostly tall, upright structures, with heights generally exceeding 50 meters. Flue gas desulfurization towers are subjected not only to pressure, temperature, and gravitational loads, but also to dynamic loads such as wind loads and seismic loads. The magnitude, direction, and even the point of application of dynamic loads change over time. These dynamic loads cause the structure to accelerate, leading to resonance phenomena and an increased risk of vibration-related accidents. http://img52.chem17.com/9/20160313/635934928755910084788.jpg Therefore, the materials used for corrosion protection in desulfurization towers must possess the following characteristics: 1) They must meet the requirements for corrosion resistance in complex chemical environments. The chemical conditions inside chimneys are complex, with flue gas containing high levels of acidity. The condensates that form on the inner surface of these chimneys are highly corrosive to most building materials; hence, the lining materials need to have strong resistance to acid corrosion. 2) They must be able to withstand temperature fluctuations. The temperature of the flue gas after wet desulfurization ranges from 40°C to 80°C. When the desulfurization system is under maintenance or not in use but the power plant is still operating, the temperature of the flue gas inside the chimney can reach 130°C to 150°C. Thus, the lining materials need to be able to resist such temperature changes, remaining intact and durable in such conditions. 3) They must have good wear resistance. Flue gas contains a large amount of dust, and combined with the corrosive effects, wear can be significant. Therefore, the corrosion-resistant materials need to have good wear resistance. 4) They must possess certain bending resistance. Considering the high altitude at which some chimneys are located, as well as factors such as Earth’s movements, earthquakes, and wind forces, the chimneys, especially at higher heights, may experience tilting or deviation. Additionally, unforeseen mechanical stresses may occur during the installation and transportation of chimneys. Hence, the corrosion-resistant materials need to have adequate bending resistance. 5) They must have good adhesion. The corrosion-resistant materials need to have strong bonding strength—not only within the material itself but also between the material and the substrate. They should also be resistant to cracking, delamination, or peeling, with good adhesion and impact strength, thereby ensuring good corrosion resistance. Generally, we require that the adhesion strength between the primer material and the steel structure foundation be at least 10 MPa or higher. The glass flake mortar anti-corrosion material has the following characteristics: 1. It boasts excellent corrosion resistance, as it uses a high-performance vinyl resin as its matrix; vinyl resin offers better high-temperature and corrosion resistance compared to epoxy resin. 2. Lower permeability, with high resistance to water vapor penetration – 6-15 times higher than that of ordinary epoxy putties and coatings, and 4 times higher than that of ordinary epoxy fiberglass FRP. 3. It possesses a high adhesion strength of >2.0 MPa, as well as an adhesion strength to concrete of >2.5 MPa; therefore, the glass flake mortar lining coating is less prone to cracking, delamination, separation, or peeling. Its good adhesion and impact strength ensure excellent corrosion resistance. 4. It has high temperature resistance and good heat shock resistance; the coating contains numerous glass flakes, which eliminate the difference in linear expansion coefficients between the coating and the steel. The linear expansion coefficient of glass flakes is 11.5x10-6/℃, which is quite similar to that of the steel, enabling this flake-based coating to withstand environments with sudden temperature changes and severe corrosion, such as those found in power system FGD systems. Under certain abnormal conditions, the temperature in certain stages of FGD processes can reach 200–250℃. We conducted heat shock tests by exposing steel plates coated with this flake-based coating to boiling water at 100℃ and ice water at 0℃ for one hour each; no abnormalities were observed after 10 such temperature shock tests. 6. It has good wear resistance; after curing, it achieves a high hardness and thus excellent wear resistance. The wear resistance of glass flake mortar is 130 mg (under the condition of CS-17W-500G). In the event of mechanical damage, the damage is limited to local areas, allowing for timely repair. 7. It is easy to apply, quality is easy to ensure, and it has a high solid content; 1–1.5 mm can be achieved in a single application. Even if damage occurs after several years of use, simple repairs are sufficient, allowing the coating to continue to be used without any loss in performance.