Why is hot air backblowing performed before a long-term shutdown of the converter in flue gas acid production?
Thread Content
This post was last edited by W Give it my all on 2025-12-29 21:25. Why is hot air backwashing performed before a long-term shutdown of the converter in flue gas acid production? After the conversion system is shut down, the SO₂ gas remaining in the catalyst layer and the heat exchanger can continue to be converted into SO₃ gas and absorbed under conditions of low air flow rate and a normal or slightly higher temperature in the catalyst layer; as a result, the amount of SO₂ emitted in the exhaust gases is significantly reduced. If hot air backflow is not used and a large volume of cold air is employed from the beginning to reduce the temperature, the temperatures of the catalyst layers in various sections of the converter will drop rapidly. Once these temperatures fall below the level required for catalyst reaction, SO₂ loses the opportunity to be converted into SO₃; as a result, the SO₂ content in the exhaust gases increases. This also causes pollution to the environment as well as to the conditions in which the catalysts are replaced.
If cooled directly, the catalyst powder at the bottom of one section will become pulverized and form scabs; meanwhile, the ceramic balls at the bottom of that section will get stained, and the support screen at the bottom will also be corroded.