In the petrochemical plant, the sulfur content increased from 1% to 2%, leading to corrosion in the distillation towers and furnaces

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Increasing the sulfur content from 1% to 2% significantly exacerbates high-temperature sulfur corrosion in distillation towers and furnaces, especially in areas where the temperature is above 240°C. The corrosion rate increases as the sulfur content rises, which can lead to uniform thinning of the equipment or even leaks. According to the mechanism of high-temperature sulfur corrosion, when the concentration of active sulfides in the medium (such as H₂S and elemental sulfur) increases, the FeS protective film formed on the metal surface is easily washed away by the rapidly flowing medium, resulting in the continuous exposure of the metal matrix and subsequent corrosion. The corrosion rate reaches its peak at around 425°C, and areas such as the bottom of the distillation tower, the oil transfer lines, and the heating furnace tubes are typical high-risk zones. Furthermore, an increase in sulfur content also raises the amount of SO3 generated in the flue gases, which can lead to molten corrosion caused by low-melting-point sulfates, further damaging the metal oxide layer. For carbon steel, if the silicon content is below 0.10%, the corrosion rate will be even more significant. To address this issue, the following measures are recommended: Material upgrade: Use Cr-Mo steel (such as Cr5Mo) or 300 series stainless steel in critical areas to improve resistance to sulfur corrosion. Control the flow rate: Avoid allowing the medium flow speed to exceed 30 m/s to reduce the risk of erosion and corrosion. Process optimization: By adding corrosion inhibitors and adjusting operating temperature and pressure profiles, the accumulation of corrosive substances is reduced. Enhance monitoring: Use online corrosion monitoring techniques (such as resistance probes) to monitor wall thickness changes in real time.