Delayed Coking Unit (DCU)

Delayed coking, along with steam cracking, visbreaking, and thermal cracking, is a thermal refining process in which hydrocarbons are converted through thermally initiated radical reactions. Delayed coking primarily produces petroleum coke from heavy fractions, with gasoline and lighter fractions as by-products. As a downstream unit, the delayed coking unit (DCU) processes residual feedstocks from upstream refining. These feeds, which are rich in sulfur species, heavy metals (e.g., vanadium and nickel), olefins, and nitrogen compounds, tend to accumulate contaminants that exacerbate operational challenges and accelerate equipment degradation. In the high-temperature sections of the DCU, common damage mechanisms include creep, thermal fatigue, and temper embrittlement. Additionally, low-temperature areas, such as the overhead systems of the main fractionator, are prone to corrosion caused by sulfur or chloride compounds.
#High Temperature Corrosion; #Sulfidation; #HCl Corrosion; #NH₄Cl Corrosion