Ebullated Bed Hydrocracking Research Articles

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

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.

Laboratory and commercial investigation of ebullated bed residue hydrocracking performance during processing of Urals crude vacuum resid and its blends with vacuum gas oil and atmospheric residue

This study focuses on investigating the conversion behaviour of vacuum residue and blends with heavy VGO (480-540°C) and atmospheric residue (340°C+), three fractions originating from the same Russian export blend crude oil (REBCO), in a laboratory ebullated bed hydrocracking pilot plant unit and in the LUKOIL Neftohim Burgas commercial H-OilRC hydrocracker. It was found that the vacuum residue conversion was 1.7 times as high as that of the VGO at the same operating conditions in both laboratory and in the commercial H-OilRC hydrocracking unit. No increase in the sediment content of the atmospheric residue product, obtained during hydrocracking of the lighter feeds, was observed. It was found that the vacuum residue H-Oil hydrocracking is best described by 1.5 order kinetics. This study showed that co-processing of distillate material (mainly vacuum gas oil) is an option to increase capacity of an existing H-OilRC residue hydrocracker while also improving the VGO product quality without adversely impacting sediment levels in the unconverted residue product. [Received: February 2, 2017; Accepted: September 21, 2017]

Converting Vacuum Residue Into Light Fuels By Self-Fluidized Pump-Free Ebullated-Bed Hydrocracking

Converting Vacuum Residue Into Light Fuels By Self-Fluidized Pump-Free Ebullated-Bed Hydrocracking

Investigation of the liquid recycle in the reactor cascade of an industrial scale ebullated bed hydrocracking unit

Abstract One of the commercial means to convert heavy oil residue is hydrocracking in an ebullated bed. The ebullated bed reactor includes a complex gas–liquid–solid backmixed system which attracts the attention of many scientists and research groups. This work is aimed at the calculation of the internal recycle flow rate and understanding its effect on other parameters of the ebullated bed. Measured data were collected from an industrial scale residual hydrocracking unit consisting of a cascade of three ebullated bed reactors. A simplified block model of the ebullated bed reactors was created in Aspen Plus and fed with measured data. For reaction yield calculation, a lumped kinetic model was used. The model was verified by comparing experimental and calculated distillation curves as well as the calculated and measured reactor inlet temperature. Influence of the feed rate on the recycle ratio (recycle to feed flow rate) was estimated. A relation between the recycle flow rate, pump pressure difference and catalyst inventory has been identified. The recycle ratio also affects the temperature gradient along the reactor cascade. Influence of the recycle ratio on the temperature gradient decreased with the cascade member order.

Feasibility of Bitumen Production from Unconverted Vacuum Tower Bottom from H-Oil Ebullated Bed Residue Hydrocracking

In relation to the constant requirement for reduction of sulfur level and low demand for fuel oil, this study presents an approach for utilization of unconverted vacuum tower bottom (UVTB) from the ebullated bed hydrocracking process, H-Oil technology, in bitumen production. The kinetic study shows a slower softening point increase for crude blend 70% Urals and 30% Middle Eastern than other feeds in the air-blowing process. Also, penetration values for straight run vacuum residue feeds decrease quicker than the increase in their softening point values. UVTB softening point increase at high temperature is faster and penetration decrease is slower than LNB SRVR. Air blowing is shown to improve the penetration index of UVTB to a greater extent than the SRVR one. The bottleneck of this new application of UVTB is its low resistance to hardening, determined by using a rolling thin film oven (RTFO), which limits its quantity up to 20–30% in blends.

Dependence of visbroken residue viscosity and vacuum residue conversion in a commercial visbreaker unit on feedstock quality

Nine vacuum residual oils were characterized and eight blends of them were processed in the LUKOIL Neftohim Burgas commercial visbreaker unit. It was found that at constant content of about 8vol.% of the fraction boiling up to 360°C (diesel cut) in the visbroken residue the visbroken residue viscosity correlated with the vacuum residual oil visbreaker feed viscosity with a squared correlation coefficient R2>0.98. By application of correlation analysis and intercriteria analysis the vacuum residual oil feedstock parameters which have statistically meaningful impact on conversion to product boiling below 360°C were found to be vacuum residual oil sulfur and hydrogen content, and solubility power of maltenes. The results obtained in this work are consistent with those obtained from other groups, even for other types of vacuum residue processing like ebullated bed hydrocracking. The vacuum residual oils which contained more resinous-asphaltenic materials formed more asphaltenes in the process of thermal conversion. The vacuum residual oil viscosity increment with increasing of asphaltene content for the straight run vacuum residual oils can be described by a second order polynomial. The secondary vacuum residual oils — the visbroken vacuum residual oils exhibited a lower than straight run residual oil dependence of the residue viscosity increment on increasing of the asphaltene content.

Reactivity and stability of vacuum residual oils in their thermal conversion

Thirteen vacuum residual oils originating from Russia, Middle East, Asia, and South America were thermally cracked in a modified high-temperature–high-pressure batch autoclave reactor. It was found that the colloidal stability of the vacuum residual oils expressed by S-value was the dominant factor that affected the residue thermal reactivity. SARA analysis data of the residual oils were confirmed to contain insufficient information about residue thermal reactivity and colloidal stability. It was found that the higher the colloidal stability of a residual oil the lower residue thermal reactivity and the steeper colloidal stability reduction during thermal conversion. The asphaltene solubility was found to linearly decrease with the increase of the thermal conversion, while the maltene solubility power did not always decrease with the increase of the thermal conversion for the studied residual oils. Having in mind that the ebullated bed residue hydrocraking H-Oil process is also based on thermal conversion the properties of commercial straight run Urals vacuum residue (UVR), visbreaker residue obtained by thermal cracking of UVR (UVBR), and ebullated bed hydrocracking (H-Oil) unconverted residue were investigated. It was found that asphaltene solubility lowered linearly with increasing of conversion regardless of the process: visbreaking or ebullated bed hydrocracking. The maltene fraction average molecular weight seems to decrease with the increase of the residue thermal conversion processes visbreaking and ebullated hydrocracking as the asphaltene average molecular weight does for the same processes. It was found that the atmospheric gas oil fraction from visbreaker has no negative effect on residual oil colloidal stability while the vacuum gas oil fraction has negative impact on residue stability in both visbreaker and H-Oil unconverted residual oils. The data generated in this work study suggest that the asphaltene solubility has a bigger impact on the residual oil colloidal stability than the maltene solubility power.

Controlling Sediments in the Ebullated Bed Hydrocracking Process

To evaluate the effect of decanted oil (DO) from fluid catalytic cracking (FCC) units on product sediments in the ebullated bed hydrocracking process (EBHP), an experimental investigation was carried out, in which the reduction of sediments was evaluated by injecting DO into different points of the EBHP. This study was carried out in a H-Oil pilot plant, in which the operation of the industrial EBHP was simulated. To evaluate the effect on the reaction system, DO was injected into the feedstock drum, and to evaluate the effect on the product recovery section, DO was injected into different points of this section. The amount of oil injected was 5 and 10 vol % based on the fresh feed. Experimental results indicate that, when DO is injected together with the feedstock, its effect on sediment reduction is marginal. However, when DO was injected into the product recovery section, sediments were reduced up to 40%. The effect on the reaction system was marginal because the aromatic hydrocarbons of the DO, which should help to maintain asphaltenes in solution, were saturated in the reactors. The effect on the product recovery section may be explained by the asphaltene solubility on the aromatic hydrocarbons of the DO, which contributed to maintain asphaltenes in solution.

Combined process schemes for upgrading of heavy petroleum

Key refinery technologies for upgrading of heavy oils feasible to be combined to increase yield and quality of upgraded oil are reviewed and analyzed. Hydrogen addition and carbon rejection based technologies are described to establish their current situation for heavy oil and residue upgrading. Various integrations of upgrading processes were identified in the literature and others have been proposed, which include deasphalting, gasification, delayed coking, RFCC, ebullated-bed hydrocracking, slurry-phase hydrocracking and fixed-bed hydrotreating. The main advantages of the integrated process schemes were highlighted in terms of product yields, quality of products, elimination of low-value by-products and reduction of impurities.

Thermodynamic Model of Sediment Deposition in the LC-FINING Process

The LC-FINING ebullated bed hydrocracking process is used to hydrocrack residuum. In this process, sediment deposition in the downstream equipment sometimes affects the overall economics by limiting the operating conversion, even though the upstream reactor system is capable of achieving much higher conversion levels. The sediment is measured by SHFT value (Shell Hot Filtration Test method), which mainly measures that portion of the asphaltene that is insoluble in heavy oil at specific laboratory test conditions. A solubility-theory-based thermodynamic model is developed to predict the SHFT value. According to this model, asphaltenes are in equilibrium (in solution) with the surrounding fluid. The model parameters are asphaltene molecular weight and its solubility parameter. Both are related. The solubility parameter is modeled as a function of the hydrogen/carbon (H/C) atomic ratio of the heavy oil. The molecular weights are estimated from pilot plant data by minimizing the sum of squares of the residuals between the observed SHFT value and the calculated value for all runs. The asphaltene molecular weight decreases with an increasing process severity, indicating that the asphaltene becomes more aromatic by losing side chains. The simple model is able to explain the observed trends with respect to different LC-FINING catalysts, feed sources, and diluent effects. Commercial data is compared to the pilot plant data, and the model prediction validates the model.

A framework for implementing on-line diagnostic advisory systems in continuous process operations

The application of diagnostic knowledge-based systems to continuous operations involving gas-solid or gas-liquid-solid reactions is analyzed. As a complex reasoning activity, diagnosis is decomposed into its constituent information-processing tasks(IPTs). The important IPTs are described in terms of their input, output, knowledge representation and inferencing strategy. How these tasks interact and are integrated to form a framework for constructing knowledge based diagnostic systems is described. A three phase ebullated bed hydrocracking units is used to illustrate the concepts of the task-based method for building knowledge-based systems. It is shown that this approach provides a natural basis for bringing together a variety of technologies into a comprehensive system for automated diagnosis.