Interactions of Active Sulfur Compounds and Impact on Sulfidic Corrosion in Crude Oil Distillation Environments (C2026-00117)

Hui Li, Yuhchae Yoon, Russell Kane

Effect of active sulfur compounds on corrosion of crude distillation units and associated piping is of great interest to refining operators. Processing crude oils with the right level of active sulfur could yield protective sulfide scale to mitigate naphthenic acid corrosion, while those with high concentrations of active sulfur might lead to increased corrosion rates due to sulfidic attack. A previous paper presented findings on H2S evolution stemmed from thermal decomposition of single active sulfur compounds. This paper focuses on the behavior of active sulfur mixtures composed of different types and concentrations of sulfur compounds, and the relevant impact on corrosion rates of several alloys commonly used in crude distillation units. Interactions of sulfur compounds were found in certain temperature ranges. Temperature, type of active sulfur and concentration, and residence time were identified as the key factors governing the extent of sulfur breakdown. Based on the experimental results, a model was developed to correlate these factors with evolved H2S partial pressures, which were used to predict sulfidic corrosion rates. The findings improved the understanding of effect of sulfur mixtures and contributed to more accurate corrosion prediction, providing better assistance with material section and crude corrosivity assessment.