Investigation of the coking behavior of serial petroleum residues derived from deep-vacuum distillation of Venezuela extra-heavy oil in laboratory-scale coking

The coking behavior of serial petroleum residues derived from deep-vacuum distillation of Venezuela extra-heavy oil has been systematically investigated in laboratory-scale coking appliances from the perspectives of distribution and properties of coking products. The usage of residue with deeper distilling cut would favor the decreasing of low-value products, i.e., coke and coking gas. The hydrogen circumstance of coking feedstock indicated by H-1 NMR analysis, implies residue with ultra-deep distilling cut as a valid hydrogen evolution potential. By comparison with the de-metallization rate in the hydrodemetallization process (Ni, 61.2%; V, 80.8%) (Zhang et al., 2006), the performance in the study seems more promising. Evidently, the stripping of VGO would notably change the morphological characteristics of resultant coke. However, no secondary assembled or clustered shot coke was observed in the coker, which made the decoking quite easy. A valid linear agreement between the area of green region quantitatively assessing the process flexibility and the metal content has been established. The extrapolation (dot line) of the trend suggests that shot coke formation cannot be avoided in any circumstance of the study if the metal content of coking feedstock is over 1516 mu g g(-1).