The Formation And Spontaneous Combustion Tendency Of Sulfide Products From Oil Refinery Equipment Corrosion

The problem of sulfur corrosion of oil refinery equipment is improving with the increasing of sulfur content in imported crude oil. The accidents caused by oxidation heat of sulfur corrosion products occur frequently. The study on spontaneous combustion tendency and effect factors of iron sulfides formed from different ways, is important for production.The experiment simulated the formation of sulfur corrosion products in different ways, based on the mechanism of sulfur corrosion. The spontaneous combustion tendency of iron sulfides was investigated. It shows that, under both low and high temperature corrosion condition, sulfur corrosion products from iron oxides are iron sulfides with complex component and molecular structure, and they have higher spontaneous combustion tendency. Because of the water and S, iron sulfides from low-temperature have higher self-heating characteristics. The different morphology of iron sulfides from Fe₂O₃, Fe₃O₄ and Fe(OH)₃ were observed by SEM, and it is the main reason for their different self-heating characteristics. Both sulfur corrosion product of low-temperature electrochemical corrosion and co-melting FeS have single component and molecular structure. They have low spontaneous combustion tendency, but they can change into Fe₂O₃ during oxidation slowly in the air.The mechanism of key effect factors was researched. It shows that, the increasing of air flow rate can improve oxygen concentration, accelerate oxidation reaction. The improving of ambient temperature can't markedly improve the velocity of reaction, but it can activate more iron sulfides such as FeS₂, the spontaneous combustion tendency can be improved. 60% water content can restrain the spontaneous combustion tendency of iron sulfides, but 5% water content conduce to oxidation reaction. Because a little water can join the reaction and produce S.The general analysis of spontaneous combustion tendency of iron sulfides shows, the essential of spontaneous combustion of iron sulfides is the process of S and oxygen produce SO₂ under the catalysis of iron oxides.