Recommended materials for catalytic cracking unit towers and other equipment
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The towers and other equipment in a catalytic cracking unit mainly include fractionation towers, top reflux tanks, light cycle oil stripping towers, heavy cycle oil stripping towers, absorption towers, and desorption towers. Their shells are generally made of carbon steel + 0Cr13Al (0Cr13) composite plates, while the trays are made of 0Cr13, 12AlMoV, or aluminized carbon steel.
Aluminized carbon steel: Process – Alumination of the carbon steel surface (by hot-dip plating or powder embedding) to form an Al₄C₃ diffusion layer and an Al₂O₃ surface film. Features: Resistant to high-temperature oxidation and sulfide corrosion, with a cost that is only 1/3 of that of stainless steel. Suitable for environments of 450–600°C, such as the top trays of distillation columns. Limitations: The thickness of the aluminized layer is limited (usually 0.1–0.2 mm), and corrosion must be monitored regularly.