H-Oil Process Research Articles

Study on The Effect of Solid Properties on The Hydrodynamics in an Ebullated Bed Reactor

Published data on the hydrodynamics of ebullated- bed reactors (EBRs) used in the H-Oil process are scarce. In the present work, the effect of solid properties (e.g., particle size, and degree of hydrophobicity) on the hydrodynamics and foaminess in a lab-scale cold model of an (EBR) was investigated. 20wt. % MgSO4 solution was utilized as the liquid phase to imitate the hydrodynamic trends in the industrial-scale EBR of the hydro-conversion process. Experimental results depicted that the flow regime of the multiphase system can be readily evaluated by using the pressure drop technique. The turning from the bubbly to the turbulent system is enhanced with diminishing particle size, and decreasing particle hydrophobicity. Moreover, the degree of particle hydrophobicity was inversely proportional to the average gas holdup in the EBR. The reduction in average gas holdup was 7.9 % using hydrophobic particles more than that of the hydrophilic one. In the EBR, it was found that bubble sizes were increased with both gas velocity and the axial location far from the gas distributor while liquid velocity has negative impact on bubble size. The experimental work revealed that hydrophobic particles of smaller size (250 μrm) reduced foaming by 70% using 20 vol. % of solid loading and gas and liquid velocities of 10 and 0.15 cm s-1 respectively. This outcome revealed that the surface of catalyst particles used can be modified to act as foaminess- reducer in fluidized bed hydro conversion reactors.

Технология MELANGETM одностадийного производства битума без окисления

The innovative technology MELANGETM allows produce of the bitumen in one stage with the required properties, according to the technical request of the Customer, from the heavy oil residue basis on the use of physical and induced by them chemical processes. In this case, the main physical processes are heating and homogenization of various heavy residues upon heating, that is, mechanical mixing, almost to an ideal state, in parallel with the addition of a polymer capable of forming long spirals and chains in dispersed media. The experimental work was the basis for the trial production of bitumen according to the European standard BDS EN12591: 2009, which was successfully implemented using the MELANGETM technology at the LUKOIL Neftochim Burgas AD refinery (Burgas, Bulgaria). The heavy unreacted fluidized bed hydrocracking (VTB) residue of the Axens France H-oil process was used as feedstock. Based on the results of experimental work and the basis of confirmed data from the Customer, a patent of the Russian Federation No. 272118 " Method of producing road bitumen from a heavy residue" was issued. MELANGETM technology allows solving the problem of utilizing low-margin heavy oil residues, including unconverted residues from high conversion of oil residues, into high-margin products such as road bitumen and bituminous binders.

Hydrodynamic Study of an Ebullated-bed Reactor in the H-oil Process

The effectiveness and performance of industrial hydro-processing ebullated bed reactors (EBRs) are highly dependent on the bed hydrodynamics and operating conditions. Hydrodynamics of ebullated bed reactors was studied in a cold model experimental setup. The results of a dynamic similarity test showed that the experimental data could be applied in the study of a large scale unit (Refinery of Lukoil, Burgas, Bulgaria) within a reasonable accuracy. Air and magnesium sulfate 20 wt% (MgSO4 + H2O) solution and solid catalyst particles were used as the gas, liquid and solid phases, respectively. For the design of experiments in the lab-scale cold-flow column, factorial method was introduced to study the influence of operating variables on the individual holdups and bubble characteristics. Pressure gradient method was used to estimate the individual holdups and bed porosity along the column, while photographic method was utilized to obtain images of the moving gas bubble. The images were analyzed using Ai Adobe illustrator CC (64 Bit) software to determine the bubbles geometric characteristics. Large gas bubbles were broken to smaller ones due to the increased turbulent intensity and shear forces at higher liquid velocities, reducing mass transfer resistances. Empirical correlations were developed for prediction of phase holdups and bed porosity with high accuracy. The results showed that liquid internal reflux ratio, which characterized the ebullated bed reactors has a predominant effect on the individual holdups and bubble size. A good agreement was observed between the results and available data in the literature.

Modeling and Kinetic Study of an Ebullated Bed Reactor in the H-Oil process

The present work was devoted to investigate the kinetic behavior of an industrial-scale ebullated bed reactor, licensed by Axens Co., in Lukoil refinery at Bourgas, Bulgaria. Another objective of the present work is to formulate a steady state mathematical model to predict the profile of products along the reactor, and to investigate effects of the operating variables [e.g., operating temperature, weight hour space velocity (WHSV), and reaction time] on the kinetic parameters, and performance of the industrial ebullated bed reactor. A five-lump kinetic model was utilized to describe the catalytic hydrocracking of heavy oil and to formulate the reaction rate equations of the main components of heavy oil. The formulated model was validated by comparing its outcome with experimental measurements of fractions of VR, VGO, and N at the effluent of industrial reactor against residence time. Results revealed an opposite relationship of the effectiveness factor with both temperature and WHSV. Results showed that the activation and deactivation energies were approximately equal, indicating that catalyst deactivation has no appreciable effect on the hydrocracking reactions in the ebullated bed reactor. The hydrocracking reactions of vacuum residue to lower molecular weight components are preferentially obtained in the following descending order: VGO; middle distillates; naphtha; gases. WHSV has a negative effect on the yield of the industrial reactor while the trend was different with the operating temperature. Outcomes of the formulated model were compared with the data reported in the literature.

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.

Activity of hydroprocessing catalysts prepared by reprocessing spent catalysts

In this study, two spent catalysts from the 3rd and 4th fixed beds of the atmospheric residue desulfurization (ARDS) process and one spent catalyst from the H-Oil process employing the expanded bed were used as the starting material for preparation of hydroprocessing catalysts. The spent catalysts were used either in a coked or decoked form. The procedures involved pulverizing the spent catalysts before mixing, kneading and extruding with boehmite in the presence of peptizing agent such as HNO 3. The hydrodesufurization (HDS) and hydrodemetallization (HDM) activities of the new catalysts were evaluated in the microreactor using the atmospheric residue derived from Kuwait crude. The new catalysts prepared from the spent catalysts used in the fixed bed reactors exhibited higher activity than that of commercial catalysts. The HDS activity of the new catalysts prepared from spent catalysts used in the ebullated bed reactor was much lower than that of the other catalysts. This was attributed to a high content of vanadium in the former spent catalyst. At the same time, the adverse effect of vanadium on HDM was much less evident.

Plugging problems observed in severe hydrocracking of vacuum residue

Carbons deposited on the filter after the reactor of hydrocracking (US-Sludge) and in the heat exchanger (DS-Sludge) in a commercial H-Oil process were analyzed through the elemental analysis, XRD, SEM, optical microscope, 13C-NMR and Raman spectroscopy to elucidate their formation mechanism. Heat treatment of sludge and oil products recovered from the commercial process was performed at 698 K of a reaction temperature. XRD showed the presence of Fe 1− x S, NaCl, and CaSO 4 as well as carbon (2 Θ = 26.6°) in US-Sludge. The carbon showed medium and fine mosaic textures surrounding the isotropic grains. DS-Sludge showed mixed texture of domain and flow surrounding the fine mosaic grains. The sludge consisted of stacked carbon flakes with a number of pores on the surface. EDX showed dominant presence of NaCl and CaO particles in the mosaic region. Heat treatment of asphaltene in the product mixed with US-Sludge gave the same appearance to that of DS-Sludge. US- and DS-Sludge are concluded to be formed through the respective carbon formation in the reactor and to be separated on the filter and on the heat exchanger surface, respectively. The carbon particles produced in the reactor collect contaminant Fe 1− x S and CaSO 4 particles to form the agglomerate where the growth and coalescence of the anisotropic spheres are very restricted to form the fine mosaic texture as observed in the US-Sludge. In contrast, the carbonization of the major precipitated heavy aromatic component leads to the domain or flow anisotropic texture through rather free growth and coalescence of anisotropic spheres on the surface of the heat exchanger wall. Although some parts of precipitated component together with US-Sludge give mosaic texture through the restricted growth and coalescence of anisotropic sphere by the presence of reactive fine solids.

Structural Characterization of Asphaltenes from Raw and Desulfurized Vacuum Residue and Correlation Between Asphaltene Content and the Tendency of Sediment Formation in H-oil Heavy Products

Asphaltenes obtained from raw vacuum residue from Russian (Ural) petroleum have been characterized by means of elemental analysis and 1H proton nuclear magnetic resonance (NMR) and compared with asphaltenes separated from the residue desulfurized in the H-oil process. The latter have much lower molecular weight and more aromatic character. In high-temperature conditions of fractionation of the whole H-oil product and in the presence of catalyst dust carried away from reactors, asphaltenes tend to condense, dehydrogenate, and separate from the desulfurized oil as a coke-like sediment. Some correlations have been found between the asphaltene contents of raw and desulfurized residue and the tendency of sediment formation in desulfurized residual oil that causes serious operating problems in H-oil units.

Contribution of Analytical Tools for the Understanding of Sediment Formation: Application to H-Oil® Process

Analytical studies were performed concerning the H-Oil® Process to better understand the mechanisms involved during residue conversion and the possible formation of sediment. Asphaltenes present in residue are known to behave as colloïdal species since they form micelles, aggregates and can flocculate depending on the temperature, pressure and solvating power of the other hydrocarbons in the residue. In this study, different catalysts were tested in the H-Oil Process pilot units and the stability of effluents was evaluated using the Martin–Bailey and the IP methods. To obtain a more detailed insight into the characterization of the residue, the following analyses were performed: group-type separation of effluents (S.A.R.A method) followed by elementary analyses of the fractions, nickel and vanadium content, molecular weight distribution by steric exclusion chromatography, and X-ray diffraction to obtain the Yen parameters of the asphaltenes in the solid state. Additionally, a solvent fractionation of the asphaltenes was evaluated in order to reach the “hard core” asphaltene which is considered to be important in sediment formation. We will show data trends obtained from these characterizations and the way that these analytical techniques can further contribute to the better knowledge of the H-Oil® Process.

Improvements of Ebullated-Bed Technology for Upgrading Heavy Oils

Improvements of Ebullated-Bed Technology for Upgrading Heavy Oils — Residue from heavy crude oils can be upgraded through various existing processes. Among these processes, the catalytic hydroconversion ebullated-bed process (H-Oil) has the unique feature of deeply converting heavy feedstocks with high impurity contents while operating with a long cycle time. This is accomplished through daily on-line catalyst replacement of a small portion of the catalyst bed. The ebullated-bed reactor includes an internal recirculation of the reactor liquid to ebullate the catalyst bed. The paper will present background information on the H-Oil process and discuss some of the recent improvements that have been developed for this technology. A Residence-Time Distribution (RTD) study was conducted using a radiotracer on a new laboratory bench unit of this process. This experiment quantified the reactor hydrodynamics and the liquid holdup. These parameters are critical to insure a safe extrapolation of the pilot plant results. The technology of H-Oil process was improved for heavy feedstocks. A new hot high-pressure separator design, based on R&D studies, has been developed to improve the separation of gas/liquid avoiding excessive liquid carry-over and gas carry-under. The use of this new separator in a commercial H-Oil plant operation at higher feedstock throughput results in improved operation and minimization of operating costs.

Influence of the solids R.T.D.F. on the conversion in three phase fluidized bed reactors

Three phase fluidized bed reactors (F.B.R.) are used industrially for the hydrodesulfurization of petroleum products (see for instance the H-oil Process) and are suitable for continuous operations since, thanks to the large catalyst size, the solids separation from gas and liquid is easier than in other slurry reactors. The continuous catalyst flow rate in the reactor and its renewal are necessary because of catalyst deactivation. In this paper a theoretical investigation is presented in which the influence of the Residence Time Distribution Function and of the solids mean residence time on the conversion rate in three phase fluidized bed reactor is evaluated. The deactivation equations for the HDS catalyst suggested by Shah, Mhaskar and Paraskos (1976) and by Raiagopalan and Dan Luss (1979) were used. It is shown that, when the deactivation of the catalyst is very rapid or the residence time of the solids rather long, the R.T.D.F. of the solids affects the conversion degree substantially. For instance, in the two extreme conditions of: 1. solid-liquid perfectly mixed systems and 2. solid-liquid with ideal plug flow at different velocities, and for peculiar values of the parameters involved, the ratio between conversion degrees with the models b) and a) may vary up to 30%.</lt>

Hydrodesulfurization of Fuel Oil

The hydrodesulfurization of fuel oil was reviewed. The minor component in fuel oil was tabulated. The engineering problems on the hydrodesulfurization was discussed, especially, work performed in a fluidized bed, socalled “H-Oil Process” was explained in detail. Studies on the hydrodesulfurization, which has been carried out in Government Chemical Industrial Research Institute, Tokyo, were described from two viewpoints, that are engineering problem and one of catalysts. The developement of a process, which belongs to a type of “Moving Bed” and is expected to be usefull in a commercial plant, was described with some data obtained. Catalyst employed in this process was Co-Mo-Al2O3 and the ralation between the methods of preparation and its characteristics were discussed.