Commercial Ebullated Bed Vacuum Residue Hydrocracking Performance Improvement during Processing Difficult Feeds

Abstract

The Urals and Siberian vacuum residues are considered difficult to process in the ebullated bed hydrocracking because of their increased tendency to form sediments. Their achievable conversion rate reported in the literature is 60%. Intercriteria analysis was used to assess data from a commercial vacuum residue hydrocracker during processing blends from three vacuum residues: Urals, Siberian Light, and Basra Heavy. The analysis revealed that the main contributors to conversion enhancement is hydrodemetallization (HDM) and the first reactor ΔT augmentation. The increase of HDM from 40 to 98% and the first reactor ΔT (ΔT(R1)) from 49 to 91 °C were associated with a vacuum residue conversion enhancement of 62.0 to 82.7 wt.%. The developed nonlinear regression prediction of conversion from HDM and ΔT(R1) suggests a bigger influence of ΔT(R1) enhancement on conversion augmentation than the HDM increase. The intercriteria analysis evaluation revealed that the higher first reactor ΔT suppresses the sediment formation rate to a greater extent than the higher HDM. During processing Basrah Heavy vacuum residue, a reduction in hydrodeasphaltization (HDAs) from 73.6 to 55.2% and HDM from 88 to 81% was observed. It was confirmed that HDM and HDAs are interrelated. It was found that the attainment of conversion of 80 wt.% and higher during processing Urals and Siberian Light vacuum residues is possible when the HDM is about 90% and LHSV ≤ 0.19 h−1.

Industrial Investigation of the Combined Action of Vacuum Residue Hydrocracking and Vacuum Gas Oil Catalytic Cracking While Processing Different Feeds and Operating under Distinct Conditions

“…The reduction in WABT from 430 to 405 • C also showed no effect on the ATB TSE at the end of the study period. This supports the correctness of the decision to replace the cascade mode of fresh catalyst addition with the parallel mode and the optimization of the fresh catalyst addition rate, as discussed in our recent research [31]. The data shown in Figure 6 confirm the very low fouling rate registered during this study.…”

“…Such an increase in the sediment formation rate with an increase in reaction temperature cannot be seen in the data in Figure 5. This may be attributed to the suitable catalyst addition rate strategy and the application of a parallel mode of fresh catalyst addition, as discussed in our recent research [31]. Sediment formation affinity during vacuum residue hydrocracking has been the subject of numerous investigations [36][37][38][39][40][41][42][43].…”

“…A net 540 • C+ vacuum residue conversion, which involves the transformation of material boiling above 540 • C from the feed into material boiling below 540 • C (percentage of feed), asphaltene conversion (HDAs), and hydrodemetallization (HDM) extent were computed following Equations ( 1)-( 3), as reported in our recent investigation [31]. A simplified layout of the heavy oil technological chain in the LUKOIL Neftohim Burgas refinery that includes the H-Oil and FCC processes is presented in Figure 3.…”

“…A net 540 °C+ vacuum residue conversion, which involves the transformation of material boiling above 540 °C from the feed into material boiling below 540 °C (percentage of feed), asphaltene conversion (HDAs), and hydrodemetallization (HDM) extent were computed following Equations ( 1)-( 3), as reported in our recent investigation [31].…”

“…Two models were developed to relate vacuum residue conversion to reaction temperature and reaction time. The first model was a regression similar to that developed in our recent research [31]. The second used the kinetic expression employed for a continuous stirred tank reactor (CSTR) because ebullated bed reactors are assumed to behave as such a reactor [33].…”