【Daily Question No. 043】2018.02.12
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【Daily Question No. 043】February 12, 2018: Why is it necessary to add corrosion inhibitors to the distillation system of hydrogenation units? What is the principle? The reference answers will be visible after responding; points are awarded by identifying the key points. The overhead stream from the stripping tower contains large amounts of hydrogen sulfide and water vapor, which can form hydrosulfuric acid and cause severe corrosion to the equipment and pipelines. Therefore, the injection of corrosion inhibitors is used to prevent corrosion of these equipment and pipelines ； Corrosion inhibitors are oil-soluble and water-soluble; they contain polar groups, and their molecules can adsorb onto the metal surface to form a protective layer that prevents corrosive agents from coming into contact with the metal, thereby providing protection. “My Registration Season” event – (currently ongoing in the Chemical Engineering section) https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1897835 Summary of daily questions related to chemical engineering registration in 2017: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1866965 Summary post of daily questions for the Chemical Engineering Engineer registration program in 2018: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1888974
The overhead stream from the stripping tower contains large amounts of hydrogen sulfide and water vapor, which can form hydrosulfuric acid and cause severe corrosion to the equipment and pipelines. Therefore, corrosion inhibitors are injected to prevent such corrosion. These inhibitors are either oil-soluble or water-soluble; they possess polar groups that enable their molecules to adhere to the metal surface, forming a protective layer that prevents corrosive agents from coming into contact with the metal, thereby providing protection. Note: An excessive amount of injection does not provide good protection, while too little injection also fails to offer any protection; therefore, the amount of injection must be controlled appropriately.
The overhead stream from the stripping tower contains large amounts of hydrogen sulfide and water vapor, which can form hydrosulfuric acid and cause severe corrosion to the equipment and pipelines. Therefore, corrosion inhibitors are injected to prevent such corrosion. These inhibitors are either oil-soluble or water-soluble; they possess polar groups that enable their molecules to adhere to the metal surface, forming a protective layer that prevents corrosive agents from coming into contact with the metal, thereby providing protection. Note: An excessive amount of injection does not provide good protection, while too little injection also fails to offer any protection; therefore, the amount of injection must be controlled appropriately.
The overhead stream from the stripping tower contains large amounts of hydrogen sulfide and water vapor, which can form hydrosulfuric acid and cause severe corrosion to the equipment and pipelines. Therefore, corrosion inhibitors are injected to prevent such corrosion. These inhibitors are either oil-soluble or water-soluble; they possess polar groups that enable their molecules to adhere to the metal surface, forming a protective layer that prevents corrosive agents from coming into contact with the metal, thereby providing protection. Note: An excessive amount of injection does not provide good protection, while too little injection also fails to offer any protective effect; the amount of injection must be controlled appropriately
The overhead stream from the stripping tower contains large amounts of hydrogen sulfide and water vapor, which can form hydrosulfuric acid and cause severe corrosion of the equipment and pipelines. Therefore, corrosion inhibitors are injected to prevent such corrosion. These inhibitors are either oil-soluble or water-soluble; they possess polar groups that allow their molecules to adhere to the metal surface, forming a protective layer that prevents the corrosive agents from coming into contact with the metal, thereby providing protection. Note: An excessive amount of injection does not provide good protection, while too little injection also fails to offer any protective effect; the injection amount must be controlled appropriately
The corrosion inhibitor for hydrogenation units (WX-121D) is a specialized corrosion inhibitor developed for hydrogenation units. This corrosion inhibitor, formulated with precision, has a strong neutralizing effect on H2S-HCL-CO2-H2O and organic acids. The corrosion inhibitor for hydrogenation units (WX-121D) prevents corrosion in two ways: firstly, by altering the charge state on the metal surface, it increases the activation energy of corrosion reactions, thereby making corrosion more difficult to occur; secondly, the non-polar groups arrange themselves on the metal surface to form a hydrophobic film, which prevents most of the charges associated with corrosion reactions as well as the corrosive agents from moving, thus achieving the purpose of suppressing corrosion.
The overhead stream from the stripping tower contains large amounts of hydrogen sulfide and water vapor, which can form hydrosulfuric acid and cause severe corrosion to the equipment and pipelines. Therefore, corrosion inhibitors are injected to prevent such corrosion. These inhibitors are either oil-soluble or water-soluble; they possess polar groups that enable their molecules to adhere to the metal surface, forming a protective layer that prevents corrosive agents from coming into contact with the metal, thereby providing protection. Note: An excessive amount of injection does not provide good protection, while too little injection also fails to offer any protection; therefore, the amount of injection must be controlled appropriately.
The overhead stream from the stripping tower contains large amounts of hydrogen sulfide and water vapor, which can form hydrosulfuric acid and cause severe corrosion to the equipment and pipelines. Therefore, corrosion inhibitors are injected to prevent such corrosion. These inhibitors are either oil-soluble or water-soluble; they possess polar groups that enable their molecules to adhere to the metal surface, forming a protective layer that prevents corrosive agents from coming into contact with the metal, thereby providing protection. Note: An excessive amount of injection does not provide good protection, while too little injection also fails to offer any protection; therefore, the amount of injection must be controlled appropriately.
The overhead stream from the stripping tower contains large amounts of hydrogen sulfide and water vapor, which can form hydrosulfuric acid and cause severe corrosion to the equipment and pipelines. Therefore, corrosion inhibitors are injected to prevent such corrosion. These inhibitors are either oil-soluble or water-soluble; they possess polar groups that enable their molecules to adhere to the metal surface, forming a protective layer that prevents corrosive agents from coming into contact with the metal, thereby providing protection. Note: An excessive amount of injection does not provide good protection, while too little injection also fails to offer any protection; therefore, the amount of injection must be controlled appropriately.
Answer: A corrosion inhibitor is a substance that, when added in small amounts to a corrosive medium, can significantly slow down the rate of metal corrosion. Corrosion inhibitors can adsorb onto metal surfaces to form a monomolecular water-resistant protective layer. Most corrosion inhibitors possess functional groups containing atoms such as oxygen and sulfur; these polar functional groups adhere to the metal surface, creating a monomolecular protective film. The polar functional groups bond with metal atoms through electron pairs, while the hydroxyl groups in the corrosion inhibitor molecules cover the metal surface, forming the outer layer of this molecular film. This layer separates the metal from the corrosive aqueous environment, preventing contact between the metal surface and acidic substances. It also helps to neutralize acidic components in the fluid, regulating its acidity and thus serving to protect the metal. Since active sulfur compounds such as H2S present in the distillation system can cause corrosion to the equipment, corrosion inhibitors are added to prevent such corrosion and protect the equipment.