How to protect metals from corrosion by low-temperature, wet flue gas in flue gas systems?
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In industrial heating furnace systems, the low-temperature, wet flue gas resulting from desulfurization and denitration after passing through the heating furnaces often causes severe corrosion of equipment made of metallic and non-metallic materials. What anti-corrosion methods can be used to minimize corrosion of these devices?
How about welding corrosion-resistant material to the contact surface? Alternatively, the corresponding components can be made directly from corrosion-resistant materials, but the latter is too costly and not recommended
If the temperature is low, a flue made of fiberglass can be used
Option 1: Vinyl glass flake at 600 yuan/m2. 1. Flue gas temperature: 40–160°C; temporarily up to 180°C under emergency conditions. Option 2: Boric acid brick lining at 1,600 yuan/m2. 1. Boric acid bricks have low thermal conductivity, making them suitable as an anti-corrosion lining for chimneys. 2. When lining the facade, from bottom to top, and to prevent misalignment due to unhardened mortar, it is specified that **no more than 3 layers may be lined consecutively**. Continue with lining after the lower layer of clay has begun to set. Option 3: Sprayed polyurea at 500 yuan/m2. 1. Polyurea possesses good thermal stability and can withstand short-term heat shocks up to 350°C. Option 4: Alloy composite chimneys at 5,000 yuan/m2. 1. C-31/276/59/926/625 are the nickel-based alloys most widely used in flue gas desulfurization systems. 2. Alloy composite panels are fabricated on site and welded; they are not suitable for old chimneys.
Tubular heating furnaces are equipped with air preheaters; the heat exchange tubes can be coated, but they must be inspected and replaced regularly. The air preheater shell is constructed from acid-resistant bricks, while carbon steel coated with a protective layer is used below the dew point. The dew point of the boiler is in the flue; acid-resistant bricks can be used