What Is Behind the High Values of Hot Filtration Test of the Ebullated Bed Residue H-Oil Hydrocracker Residual Oils?

Abstract

This work summarizes the results of multiple experiments performed in the LUKOIL Neftohim Burgas Research Laboratory related to the issue of high values of hot filtration test (HFT) of the residue H-Oil hydrocracking residual oil products. After the start-up of the new residue H-Oil hydrocracker in the LUKOIL Neftohim Burgas refinery during the second half of 2015 the values of the HFT of the vacuum tower bottom product varied between 0.01 and 8.7%. It was found that the vacuum residual oil feed source has a profound effect on the processes of sedimentation in the H-Oil hydrocracker. The processing of vacuum residual oils from Arab medium, Arab heavy, and Basrah light crudes reduced the sedimentation and allowed achievement of a higher conversion. The H/C ratios of asphaltenes from all studied feeds decreased after hydrocracking. However, the decrease of the H/C ratio was the least pronounced with the Basra light asphaltenes, while the H/C ratios of asphaltenes from the vacuum residual oils originating from the crudes Urals and El Bouri became much lower. The maltene fraction H/C ratio could become lower, the same, or higher after hydrocracking depending on the feed source, catalyst metal (vanadium) loading, or the hydrocracking unit (commercial, pilot plant, or laboratory unit). It was found that after addition of high aromatic fluid catalytic cracking gas oils the H-Oil residue HFT dropped and the dependence of the residue HFT on the concentration of FCC gas oils in the blend could be approximated by a third order polynomial. Correlations were developed to predict the H-Oil based residual fuel oil HFT from information on the base H-Oil residue HFT and the amount of added fluid catalytic cracking (FCC) gas oil. The treatment of the H-Oil residual oils with commercial HFT reducers may decrease the residual oil HFT. However, the efficiency in HFT reduction turned out to depend on the nature of the H-Oil residue and on the concentration range of the HFT reducing additive. From all studied additives solely the dodecylbenzenesulfonic acid (DBSA) was capable of reducing the H-Oil residual oil below 0.1%. However, the treatment rate of the DBSA was an order higher than that of the commercial additives A, B, and C. DBSA was an order of magnitude more effective in the reduction of the total sediment existent, and the total sediment potential than the FCC HCO.

Commercial Investigation of the Ebullated-Bed Vacuum Residue Hydrocracking in the Conversion Range of 55–93%

“…Case 2 ( Table 2 ) is characterized by an extremely high sediment content in the hydrocracked ATB, and a 2-day operation at the conditions of case 2 was sufficient to shut down the ebullated-bed hydrocracker for 2 weeks for cleaning of the equipment. 59 By not being in operation for 1 day, the ebullated-bed hydrocracker experiences a loss of about 600 KUSD/day. 61 Except for case 2, all other 11 cases are characterized with the hydrocracked ATB sediment content not higher than 0.4%.…”

“…A simplified process diagram of the LNB EBR hydrocracker with the typical range of the operating condition variations is presented in ref ( 59 ). The catalyst employed in this study was a commercial Ni–Mo low sediment catalyst.…”

Colloidal stability and hot filtration test of residual fuel oils based on visbreaking and ebullated bed residue H-Oil hydrocracking

“…This suggests that the thermal aging facilitates the processes of agglomeration of the particles for those residual oils which are colloidal unstable. In our earlier study, it was found that in the H-Oil residual oils obtained from the LNB H-Oil residue hydrocracker the sediments are formed mainly due to aggregation of the insoluble asphaltenes (Stratiev et al, 2016b). Therefore, a conclusion could be made that the thermal aging procedure favours further the processes of agglomeration of the aggregated insoluble asphaltenes in the H-Oil residual oils.…”

“…Sa is related to the solubility of the asphaltenes, the length and number of the aromatic chains), and So (peptising power of oil is the 'aromatic' equivalent of the oil; it is a measure of the solvency power of the oil with respect to asphaltene solubility) were measured by the use of a modification to ASTM D7157-05 as described in Bartholdy and Andersen (2000). Stratiev in his work showed that according to the oil compatibility model of Wiehe oils whose S-value ≥ 1.4 should be considered colloidal stable, which are not prone to form sediments (Stratiev et al, 2016b). The colloidal stability parameter SN of the investigated residual oils was measured in accordance with the ASTM D7061.…”

“…The S-value minimum for the unconverted visbroken residue was set at 1.43, to provide stable and reliable production of finished fuel oil with sediment content lower than the specified 0.1%. Unfortunately, this strategy seems difficult to follow for the higher residue conversion processes like the ebullated bed residue H-Oil hydrocracking because at conversion higher than 40% during processing Urals vacuum residue the S-value gets lower than 1.3 (Stratiev et al, 2016b). However, the aim of the H-Oil residue hydrocracker is to operate at higher conversions (Stanislaus et al, 2005).…”