Sulfur is produced in the sulfur recovery unit (CS); during shutdowns, there is a high amount of moisture, which causes pipe corrosion. What do you do to address this?
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The hot nitrogen desulfurization process can effectively reduce corrosion issues during the shutdown of sulfur recovery units (CS), especially in conditions with high moisture levels; by using high-purity nitrogen for system protection, it significantly lowers the risk of pipeline corrosion. During shutdown, the residual sulfur can react with moisture and oxygen to produce sulfurous acid (H₂SO₃) or sulfuric acid (H₂SO₄), leading to severe dew point corrosion, especially in low-temperature areas such as condensers, pipelines, and catchers. Due to the limited corrosion resistance of current materials, controlling the environmental medium becomes a key means of protection. The advantages of using the thermal nitrogen desulfurization process include: using high-temperature nitrogen to purge the system, thereby effectively removing residual sulfur and acidic substances ； Avoid additional SO₂ emissions caused by fuel gas ； The inert nitrogen atmosphere blocks oxygen, inhibiting the formation of H₂SO₃/H₂SO₄, thereby reducing corrosion ； Practice has shown that this process can keep the SO₂ concentration in the exhaust gases below 400 mg/m³, significantly reducing the risk of environmental pollution and equipment damage. Despite the issues of high nitrogen consumption and long downtime, economic efficiency and productivity can be improved by optimizing operational procedures such as staged purging and nitrogen recycling.
Purge the system with high-temperature nitrogen to effectively remove residual sulfur and acidic substances；
Thermal nitrogen purging is indeed an effective method for protecting equipment during shutdowns, but several details need to be taken into account in practice: 1) The purity of the nitrogen should be maintained at over 99.9%, as even trace amounts of oxygen can still cause corrosion； 2) It is recommended to keep the purging temperature between 120–150°C, which ensures the fluidity of sulfur without causing the equipment to overheat ； 3) Our factory will install a humidity monitor after purging to ensure that the system’s dew point temperature remains at least 5°C above the ambient temperature. It is also recommended to conduct a comprehensive PTA inspection before resuming operations, with a focus on changes in the wall thickness of the condenser tube bundles.