Fouling tendency of bitumen visbreaking products

In this work, the fouling behaviour of thermally processed bitumen products obtained by visbreaking was studied. The feedstock was prepared by blending raw oil sands bitumen with 15 vol% hydrotreated light oil (HLO). The visbreaking products obtained at different pitch (525 degrees C + fraction) conversions were characterized and tested for fouling tendency. Test results showed that the fouling tendency linearly increased with total olefin content in visbreaking products. To further investigate the separate contributions of olefins and asphaltenes to fouling tendency, a selected visbreaking product was distilled into an olefin-rich 280 degrees C fraction and a heavy 280 degrees C + fraction to avoid the loss of lighter fractions during the deasphalting process. To minimize the effect of interactions between olefins and asphaltenes on the fouling tendency, the 280 degrees C fraction was hydrotreated and the 280 degrees C + fraction deasphalted. The deasphalted samples with different olefin contents and the hydrotreated samples with different asphaltene contents were obtained by blending the processed 280 degrees C and 280 degrees C + fractions. Test results showed that deasphalting significantly reduced the fouling tendency of the visbreaking product. In the presence of olefins, asphaltenes have a significant effect on the fouling tendency of thermally processed products, whereas in the absence of olefins, the impact of asphaltenes on fouling tendency was limited. Similarly, olefins have a limited effect on the fouling tendency of visbreaking product in the absence of asphaltenes.

Automated summary

This study reveals a linear relationship between fouling tendency and total olefin content in visbreaking products. Deasphalting significantly reduces the fouling tendency of the visbreaking products, and the interactions between olefins and asphaltenes have a significant impact on fouling tendency.