How does the presence of hydrogen sulfide (H2S) in refinery streams contribute to corrosion, and what mitigation strategies can be employed?

Hydrogen sulfide (H2S) is a corrosive gas commonly found in refinery streams that significantly contributes to corrosion due to its ability to react with metals, especially carbon steel, forming iron sulfide (FeS). This corrosion is particularly problematic in wet environments where H2S dissolves in water, creating a sour environment that accelerates the corrosion process. The underlying mechanism involves the electrochemical reaction between H2S and the metal surface, leading to the formation of FeS and the release of hydrogen ions. The FeS scale can be porous and non-protective, allowing further corrosion to occur. Additionally, H2S can promote hydrogen embrittlement, where atomic hydrogen diffuses into the metal, reducing its ductility and increasing its susceptibility to cracking. The presence of H....