Ebullated Bed Reactor Research Articles

CFD assessment of internal Vapor/Liquid separator in an ebullated bed reactor (EBR) for heavy oil hydroprocessing

The ebullated-bed reactor (EBR) is an important system used in the upgrading of heavy oil residue into valuable light products in petroleum refinery operations. The assessment of the gas separation region hydrodynamics is very significant to investigate the performance of EBR. An advanced understanding of EBR fluid dynamics will help in improving the design of existing and future commercial units. For this reason, the development of a computational fluid dynamics (CFD) model is very challenging, where understanding the fundamentals of fluid dynamics in EBR is carried out using a three dimensional model and the turbulence model with a standard wall function in cup geometric design. The two models were used to analyze the influence of operational parameters such as recycle ratio, and inlet velocity on gas fraction recycled and separation efficiency. Moreover, the prediction of the regime transitions occurring in the freeboard region of the EBRs was achieved using the two aforementioned models. The results of the fluid dynamics behavior revealed that the inlet velocity has a substantial effect on gas fraction recycled and separation efficiency. The liquid mean residence time scale provided a valuable efficiency result for the separation within the range of expected mean residence times. This investigation, therefore, provided a good framework for the evaluation of future design and gave a better understanding of gas and liquid flow patterns in EBR.

Research on the coupling principle of revolution and self-rotation of catalysts in a bio-oil hydrodeoxidation ebullated bed reactor

As a renewable and environmentally friendly resource, biomass energy has been widely used and is considered to be a promising alternative to petroleum-based liquid fuels. At present, the ebullated bed reactor is generally used to upgrade the biomass pyrolysis liquid, but the catalyst is prone to deactivation due to the polycondensation and coking of bio-oil. This paper proposes an ebullated bed with a built-in axial hydrocyclone to achieve in-situ activation of the catalyst. The influences of the vortex finder insertion depth and the inlet flow rate on the particles' revolution and self-rotation were investigated by numerical simulation, high-speed imaging technology and particle image velocimetry (PIV), and the coupling principle of revolution and self-rotation of catalysts was also analyzed. The results show that increasing flow rate and decreasing vortex finder insertion depth will increase the particles' revolution speed, which varies in the range of 18–78 rad/min. The particles' self-rotation speed varies in the range of 240–1200 rad/min. With the increase of flow rate and vortex finder insertion depth, the particles' self-rotation speed increases, the attached oil phase on particle pores and surfaces receives greater centrifugal force, the coupled centrifugal separation factor increases, and the oscillation period of the coupled centrifugal force decreases, which is beneficial to the desorption of the oil phase. The self-rotation, revolution and their coupling principle are beneficial to the removal of pore pollutants in the catalyst.

Numerical Analysis of Gas Hold-Up of Two-Phase Ebullated Bed Reactor

Due to the significant increase in heavy feedstocks being transported to refineries and the hydrocracking process, the significance of adopting an ebullated bed reactor has been reemphasized in recent years. The predictive modelling of gas hold-up in an ebullated two-phase reactor was performed using 10 machine learning methods based on support vector machine (SVM) and Gaussian process regression (GPR) in this study. In an ebullated bed reactor, the impacts of three features, namely liquid velocity, gas velocity, and recycling ratio, on the gas hold-up were examined. The liquid velocity has the most impact on the predicted gas hold-up, according to the feature significance analysis. The rotational-quadratic, squared-exponential, Matern 5/2, and exponential kernel functions integrated with the GPR models and the linear, quadratic, cubic, fine, medium, and coarse kernel functions integrated with the SVM model performed well during training and testing, with the exception of the fine SVM model, whose R2 is very low. According to the R2 > 0.9 and low RMSE and MAE values, the rotational-quadratic, squared-exponential, and Matern 5/2 GPR models performed the best.

Gas segregation in a pilot-scale ebullated bed system: Experimental investigation and model validation

Gas hold-up reduction inside hydroprocessors is critical to improving the efficiency of bitumen conversion. The use of internal gas/liquid segregation devices, such as recycle cups, has been the focus of much past research and development over the previous five decades. In this study, the effects of different recycle cup designs and working fluids were evaluated using a pilot-scale cold-flow ebullated bed reactor and compared to multiphase flow simulation predictions. Two recycle cup designs from the literature were fabricated using 3D printing technology and two working fluids were used: air-water and air-5 wt% ethanol aqueous solutions. The addition of ethanol helped create high gas hold-up and foaming conditions frequently observed in commercial hydroprocessors. It was observed that in foaming systems, the performance of the recycle cups deteriorated. Additionally, increasing the liquid flow rate, either through the inlet or increased recycle, resulted in diminished gas/liquid segregation efficiency. The accuracy of simulations using the two-fluid model was evaluated to predict gas hold-up in the pilot scale system as well as inside the recycle line. In the homogeneous flow regime, given the proper bubble size, the simulations predicted the gas hold-up in the column with less than 5% error. However, unlike the experimental observations, simulations did not predict any gas entrained in the recycle line, which is attributed to variation in the average bubble size and limitations of the existing momentum exchange closures.

Effect of Titanium tetrachloride on the rate of chlorination of Yarega quartz-leucoxene concentrate

This paper considers the results of a study that looked at chlorination of the Yarega quartz-leucoxene concentrate in an ebullated bed reactor (EBR) that feeds titanium tetrachloride vapours and their mixture with chlorine to the reaction mass. The experiments were conducted at a temperature of 850 oC and an incoming gas flow rate of 1,600 ml/min. 250–315 μm concentrate grains mixed with 160–250 μm calcined petroleum coke (the carbon to titanium dioxide molecular ratio was 5) were subjected to chlorination. The reaction products were analyzed with the help of inductively coupled plasma optical emission spectroscopy. It was found that, in the absence of chlorine, titanium tetrachloride only interacts with iron oxides. Feeding a mixture of titanium tetrachloride vapours and chlorine into the reactor leads to an intensified chlorination of the main concentrate components, including TiO2, SiO2, Al2O3 and Fe2O3. The TiO2 chlorination rate rises proportionally to the square root of the partial pressure of titanium tetrachloride in the gas-vapour mixture. The risen rate can be attributed to a higher concentration of active chlorine atoms, which in this case occur on carbon surface not only due to dissociation of molecular chlorine but also as a result of decomposition of titanium tetrachloride. A higher partial pressure of chlorine atoms leads to higher rates of reaction between the chlorine atoms and the concentrate components. According to the proposed reaction mechanism, the TiO2 chlorination rate is proportional to the square root of the product of the partial pressure of TiCl4 and the carbon grains surface area. The excessive chlorine does not impact the chlorination rate. It would be advisable to take into account the discovered ability of TiCl4 to intensify the titanium dioxide chlorination process when designing a chlorine feeding unit in the ebullated bed reactor. Feeding chlorine mixed with titanium tetrachloride vapours into the lower section of the reactor can help enhance the process performance while avoiding using too much chlorine.The work weas carried out under financial support of the Russian Foundation for Basic Research grant, the project No. 18-29-24187mk.

Hydrodynamic Properties Investigation of Ebullated Bed Reactor Using Non-Newtonian Liquid

The importance of using EBR has been renewed recently due to the sharp increase in heavy feedstocks sent to refineries and the hydrocracking process. Most of these feedstocks have a non-Newtonian behavior. The performance of this type of reactor using non-Newtonian liquid is complicated and has not been covered well yet. Hence, the present work is devoted to elucidating the effect of the non-Newtonian behavior of fluid on the hydrodynamic properties of a three-phase (gas-liquid-solid) reactor under operating conditions of different values ​​of gas velocity (2, 4, 6) cm/sec, liquid velocity (0.9, 1.39, 1.8, 2.3) cm/sec, and recycle ratio (1.5, 2, 2.5). The study observed the effect of non-Newtonian behavior using polymethyl Cellulose (PMC) at different concentrations (0.1, 0.2, 0.3, and 0.4) wt%. The pressure gradient method was used to elucidate the minimum liquid fluidization velocity and to estimate hold up, while the imaging method was used to measure the bubble's size. The results showed that the higher the gas velocity, the lower the minimum liquid fluidization velocity. As the intensity of the non-Newtonian behavior increased, gas velocity showed the opposite effect. The results also showed that increasing the velocity of liquid and gas and the intensity of the non-Newtonian increase the gas hold-up. The bubbles characteristics, represented by bubble size results, show that small bubbles appear at low gas velocities, and these bubbles collapse as gas and liquid velocities increase as well as liquid viscosity.

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.

Cold model testing of in-situ catalyst activation by swirling self-rotation in ebullated bed reactor for biomass pyrolysis oils hydrogenation

In the process of biomass pyrolysis oils hydrogenation in the ebullated bed, the catalyst faces several serious issues (e.g., short operation time, frequent addition, massive waste) due to coking and channel blocking. Based on the phenomenon of the self-rotation of particles in the rotation shear flow, an axial-flow hydrocyclone is developed to activate the catalyst. In this study, the self-rotation of particles was presented with the help of microfluidic technology and high-speed photogrammetry, and the effect of self-rotation on the deoiling efficiency of the catalysts was investigated using a catalyst activation cold model experiment. The results show that when the inlet flow rate Q and the vortex finder length hc increase, the self-rotation speed of the particles also increases. When the particles rotate, the periodic coupling centrifugal force causes interfacial turbulence between the oil attachments and the fluid, which promotes the mass transfer. When Q and hc were 0.22 m3/h and 335 mm, the self-rotation speed reaches the maximum, which is 887.4 rad/min, the content of guaiacol (coking precursor) decreases from 55.0% to 11.4%, and the content of n-Hexadecane decreases from 38.8% to 16.1%. This innovative technic will prolong the lifetime of catalysts used in the ebullated bed reactor and make biomass pyrolysis oils hydrogenation more competitive.

Analysis of performance of novel hydrocyclones in ebullated bed reactor with different vortex finder structures

A novel axial-flow hydrocyclone in the ebullated bed reactor is proposed to solve problems such as low space utilization rate, low operation flexibility and complex device structure. This study presents a numerical and experimental study of the liquid-solid two-phase flow and the performance of the hydrocyclone, with focus on the effects of length hc, taper angle αc and diameter D2 of the vortex finder over a certain range of inlet flow rates. Results show that the influence of D2 on separation performance is more significant than the influence of either hc or αc. Increasing D2, increasing hc or decreasing αc are all beneficial to improve separation efficiency, and separation performance decreases as inlet flow rate increases. When the dimension and structure of the vortex finder and inlet flow rate change, it is always accompanied by a low-level pressure drop (400 Pa–650 Pa). Considering separation efficiency and pressure drop, a hydrocyclone with a cylindrical vortex finder with hc of 335 mm and D2 of 75 mm is the optimum hydrocyclone. Overall, this study provides guidance for the design of axial-flow hydrocyclones for particle separation in ebullated bed reactors.

Ebullated bed process for high conversion of heavy hydrocarbons with a low sediment yield

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.

Internal Gas–Liquid Separation in Industrial Ebullated Bed Hydroprocessors

Ebullated bed reactors used in heavy oil upgrading internally recycle up to 90% of net liquid flow to maintain fluidized conditions. Internal phase separators result in significant gas re-entrainme...

Technology advancements in hydroprocessing of bio-oils

This manuscript describes the research and development undertaken at Pacific Northwest National Laboratory subsequent to an earlier bio-oil hydrotreating historical development review in 2007. It also includes the implications for future development needs related to hydroprocessing of biomass fast pyrolysis bio-oil for liquid hydrocarbon fuels production. The results of the research, the needs and implications for additional research and development, as well as the future potential for technology transfer to industrial application are included. The progress over the 10 years of research can be captured by the technoeconomic assessment in the reduction in cost of the product by nearly 80% of the starting assessment. Design catalyst lifetime was extended from <10 days to half a year through improvements in operational details such as catalyst formulations and operating temperatures, with introduction of sulfur guard beds (with regeneration protocols) to protect precious metal catalyst in the low-temperature stabilization bed, as well as the recycle of the heavy ends of the hydrotreated product back to the hydrotreater for product finishing. Attempted operation of an ebullated bed reactor system was unsuccessful but enlightening as to the complex phase structure experienced in bio-oil hydrotreating.

Optimization of Residual Oil Hydrocrackers: Integration of Pump-Free Ebullated Bed Process with Membrane-Aided Gas Recovery System

The ebullated bed residual oil hydrocracking is a well-established technology wherein the vacuum residue (VR) of crude oil is converted into light valuable oils. This research work targeted to optimize the hydrocracking process by integrating the pump-free ebullated bed reactor (PF-EBR) with a membrane-based gas synthetic recovery system. A PF-EBR hydrocracking unit with a feed capacity of 3 × 106 t/a (ton per annum) of vacuum residues was modeled by the axial dispersion model; the 5-lump axial dispersion model and the finite difference model for PF-EBR and membrane unit were developed and packaged as self-defined extensions in Aspen HYSYS, allowing the integrated process to be evaluated in high efficiency and accuracy; the proposed model was further validated by the experimental data of the pilot and 5 × 104 t/a industrial unit. The results of process optimizations showed that the membrane-aided separation system demonstrated better performance than the conventional condensation system in separating hydrogen and hydrocarbons from bulk refinery gas. The recovery of hydrogen from the reactor effluent resulted in 30.0% drop in reactor fresh makeup hydrogen cost; the membrane-based system separated the light hydrocarbons from refinery flash gases, which boosted the net profit of hydrocarbon recovery by 80%, leading to $122.3 × 106/a increase in the total product sale (about 7% of the hydrocracker total sale). This study bridged the gap between theoretical models and industrial PF-EBR processes and provided a designing framework for the integrate process of PF-EBR VR hydrocracking and gas synthetic recovery system. The described improvements implied significant reductions in energy cost, carbon footprint, and operational cost; the estimated reduction in CO2 emissions is around 2.6 × 104 t/a; all are attributed to the thorough gas recovery.

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.

Experimental and analysis study on dispersion of phases in an Ebullated Bed Reactor

The effectiveness and performance of industrial hydro-processing Ebullated Bed Reactors (EBRs) are highly dependent on the bed hydrodynamics and operating conditions. In present work, hydrodynamics of EBRs was studied in a cold model experimental setup using air–water–solid particles system. Pressure gradient method and Residence Time Distribution (RTD) technique were used to estimate the individual holdups, and dispersion coefficients in the lab-scale ebullated bed column. System Hydraulic Efficiency (HEF) was also estimated. The results showed that liquid internal recycle ratio, which characterized the EBRs, has a predominant effect on the individual holdups and dispersion coefficients. Empirical correlations were developed for prediction of phase holdups, and dispersion coefficients with good accuracy.

Effect of Reactor Configuration on the Hydrotreating of Atmospheric Residue

To study the effect of reactor configuration on hydrotreating, a series of experiments was carried out in a pilot plant equipped with two reactors in series that can operate in two modes: a fixed-bed reactor (FBR) or an ebullated-bed reactor (EBR). The experiments were carried out with the atmospheric residue as feedstock and commercial catalysts at a pressure of 100 kg/cm2 and temperatures of 380 and 400 °C. The highest conversions were obtained for the EBR–EBR (35.67–52.21%) and EBR–FBR (29.08–53.09%) configurations, unlike the FBR–FBR configuration that exhibited the lowest conversion (15.42–27.34%). At 400 °C, the EBR–FBR and FBR–FBR configurations showed higher hydrodemetalization than the others (81.00 and 76.95%, respectively). It was confirmed that the formation of sediments increases at high temperatures, whereas at 400 °C, it begins to be significant for the EBR–FBR and EBR–EBR configurations (0.010–0.767 and 0.041–0.613 wt %, respectively), in contrast to the FBR–FBR configuration that presente...

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.

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.

Parametric analysis of internal gas separation within an ebullated bed reactor

Ebullated bed reactors are commonly found within resid hydroprocessors used to thermally crack and catalytically hydrogenate atmosphere and vacuum tower residue in heavy oil upgrading. These units have historically experienced very high solids-free gas holdups above 30%, displacing heavy feed and limiting product throughput, with significant focus placed on the effects of the internal recycle geometry on column performance. A fully functional 3D CFD framework for simulating the gas separation region is presented here, capable of capturing tangential and rotational fluid motion and transient gas separation dynamics. The model is applied to a first-generation recycle cup separator design and is used to explore operational parameters (fluid velocity, bubble size/holdup, recycle rate, and foam generation) and the choice of momentum coupling strategy on gas entrainment and separation efficiency. The results provide a framework for comparison and evaluation of future designs as well as fundamental insight in the separation dynamics in the freeboard region of this reactor, with efforts ongoing to compare and contrast fundamental operating modes of multiple separator designs.

Application of Novel Zeolite Y Nanoparticles in Catalytic Cracking Reactions

The cracking activity of a fluid catalytic cracking (FCC) catalyst containing novel zeolite Y nanoparticles fabricated using mesoporous silica (average particle size of 150 nm) was examined and compared with the performance of other catalysts. The activity experiments were carried out in a fluidized bench-scale batch riser simulator reactor. The bulky probing compound of 1,3,5-triisopropylbenzene (TIPB) was cracked to lighter compounds over a catalyst containing 25% of the developed zeolite. The synthesized sodium-type zeolite nanoparticles were subjected to two cycles of ion-exchange treatment using ammonium sulfate and lanthanum chloride and then to calcination. To investigate the effects of particle size on the activity, three additional catalysts were prepared with the mean particle size of the supported zeolites ranging from 450 to 1800 nm. The preparation of the FCC catalysts was conducted by mixing the highly aqueous dispersed zeolite Y nanoparticles with colloidal silica–alumina as a matrix and silica sol as a binder. The results of the catalytic cracking of TIPB demonstrated the significant effect of the size reduction of the synthesized zeolite Y nanoparticles on the catalytic performance of the catalyst. The FCC catalyst that contained zeolite Y nanoparticles (150 nm) showed superior conversion and selectivity percentages for the main products. The results of this study have a direct implication on the preparation of colloidal catalysts containing zeolite Y nanoparticles, which form stable emulsion with petroleum products. These emulsions can be utilized for slurry and ebullated bed reactors in heavy oil upgrading applications.