The corrosion mechanism of the flue is due to the presence of acidic gases like SO2 and SO3 in the flue gases, which condense into dilute sulfuric acid and sulfurous acid solutions when cooled. When the flue gas temperature falls below the acid dew point, it can directly corrode metal or concrete flues. Additionally, high sulfur and chlorine content in the fuel increases the concentration of acidic substances; the denitrification and dust removal processes may introduce ammonia escape (forming ammonium salts that corrode) or moisture, exacerbating corrosion. During operation, corrosion issues are also a challenge for flues and chimneys that must be addressed. In solving flue corrosion, corrosion-resistant materials are particularly important. Currently, in China, four main types of corrosion-resistant materials for flues are used.

1. Corrosion-resistant chimney materials — fiberglass materials

Due to its chemical resistance and lower cost compared to high-nickel alloys, many wet separation system devices have achieved significant effects when using glass fiber reinforced plastic (FRP) materials for corrosion prevention. According to foreign data, FRP materials have been successfully applied in the wet flue gas desulfurization (FGD) system field: absorber towers, lime dissolution tanks, collectors, demisters, slurry conveying pipelines, flues, chimneys. Since the inner surface of FRP materials is smooth, it's less prone to dirt accumulation and is wear and acid-resistant. Therefore, they typically perform well in areas with high flow rates and high concentrations of particulate matter.

2. Corrosion-resistant material for flue duct — rubber materials

Silicone rubber linings and polyurea coatings are commonly found in our domestic market, though they lack high-temperature resistance. However, they excel in waterproof and acid resistance.

3. Corrosion-resistant material for flue—Glass Phosphate Material + Abrasion-resistant Carbonized Silica Mortar

Due to the main filling material of glass flake being SiO2, it boasts excellent temperature resistance and acid resistance, and is quite common in the market. Common applications include silicone foam glass bricks and the composite method of glass flake + wear-resistant carbonized silicon gel mortar.

4. Corrosion-resistant material for flue—Acid-resistant mortar material

The above four materials are commonly and widely used in the current applications of chimney corrosion prevention.