Continuous injection of minimum concentration will help to protect the system from corrosion. Mostly, Corrosion Inhibitors used in refinery will be dosed at overhead of distillation columns. They can be oil soluble or water soluble and can be applied for gas, oil and water phase systems.
Two types of Corrosion Inhibitors used in refinery
- Neutralizing amine
- Filming amine
Neutralizing amine for Refinery Applications
- These are chemicals added to neutralize acids present in the condensing water in refinery distillation units.
- Strong HCl and dissolved acidic gas such as H2S are neutralized to maintain the pH.
- At acidic pH values, corrosion becomes excessively aggressive, while pH values higher than 7 could lead to fouling.
- Effective neutralization is an acid base reaction formulated to have high solubility in water.
- Neutralizers would contain one or more low molecular weight amines to counteract HCl and at the same time to avoid formation of corrosive salts.
Filming amine corrosion inhibitors
- Filming inhibitors are high film persistent organic compounds, forms a hydrophobic layer that repels water molecules and subsequently retarding corrosion reactions.
- Blistering, Hydrogen Induced Cracking and stress Oriented Hydrogen Induced Cracking damage can occur throughout the refinery wherever carbon and low-alloy steels and wet-2 environments are present.
- In refinery, high-temperature corrosion that occurs mainly in crude and vacuum units, and downstream units that process certain crude oil fractions or cuts containing naphthenic acids, which are highly corrosive species.
