Intercriteria Analysis to Diagnose the Reasons for Increased Fouling in a Commercial Ebullated Bed Vacuum Residue Hydrocracker

Abstract

The intercriteria analysis developed on the base of intuitionistic fuzziness and index matrices was applied to evaluate processing data of the LUKOIL Neftohim Burgas H-Oil ebullated bed vacuum residue hydrocracker with the aim of revealing the reasons for increased fouling registered during the 3rd cycle of the H-Oil hydrocracker. It was found that when the ratio of the Δ T of the 1st reactor to the Δ T of the 2nd reactor gets lower than 2.0, an excessive H-Oil equipment fouling occurs. The fouling was also found to be favored by processing of lower Conradson carbon content vacuum residual oils and increased throughput and depressed by increasing the dosage of the HCAT nanodispersed catalyst. The fouling in the atmospheric tower bottom section is facilitated by a lower aromatic content in the atmospheric tower bottom product. The addition of FCC slurry oil not only increases aromatic content but also dissolves some of the asphaltenes in the atmospheric residual hydrocracked oil and decreases its colloidal instability index. The fouling in the vacuum tower bottom section is facilitated by a higher saturate content in the VTB. Surprisingly, it was found that the asphaltene content in the VTB depresses the fouling rate. No relation was found of the sediment content in the hydrocracked residual oils measured by hot filtration tests and by the centrifuge method to the equipment fouling of the H-Oil hydrocracker.

Synthesis of Mild Hydrocracking Catalysts for Residue Conversion

“…The API results in Figure complement the activity results, reported in Figures and , where the best overall performance was observed in MHCR-E. In addition to the API gravity, the stability of the product after heavy oil conversion should also be considered because any disturbance in the SARA fractions (saturate, aromatic, resin, and asphaltene) may result in sediment formation and asphaltene precipitation. − The overcracking of residual oil can considerably increase the saturate fraction, which consequently disturbs the balance between the other three fractions and results in asphaltene precipitation and unstable cracked oil . In addition to product instability, the precipitation of asphaltene on the catalyst surface can significantly increase the rate of coke formation and consequently the catalyst deactivation rate.…”

Study of Bulk Properties Relation to SARA Composition Data of Various Vacuum Residues Employing Intercriteria Analysis

“…This observation suggests that, similar to the full SARA composition as discussed earlier in this study, the difference in asphaltene contents in the distinct vacuum residues seems to be sample specific. In this research, we omitted discussing the relations of LNB SARA composition to vacuum residue bulk properties, which were already discussed in our earlier studies [38,40].…”

“…Some of the vacuum residues were analyzed for their four fraction SARA composition following the procedure IFP 9305. The relations between the SARA composition data and the bulk properties were evaluated by the use of intercriteria analysis (ICrA), as described in our recent research [40].…”

Application of Ebullated-Bed Vacuum Residue Hydrocracking at Lukoil Neftohim Burgas

“…Along with the feedstock quality, the catalyst condition is another significant factor that affects the conversion rate and efficiency of an H-Oil plant [ 9 ]. Thus, changes in the feedstock quality can result in changes in the VR conversion rate of up to 20 wt % [ 10 ], while the catalyst condition can cause a difference of up to 14 wt % [ 9 , 11 ].…”

“…A previously unreported phenomenon was observed during operation of the H-Oil ebullated bed hydrocracking unit at the LUKOIL Neftohim Burgas, concerning the transformation of the catalyst into a black powder in the first reactor. The powder consisted of vanadium sulfide and iron sulfide [ 11 ]. This phenomenon was observed for the first time at the beginning of 2018, during the first maintenance operation of the unit following three years of its operation.…”