Light Vacuum Gas Oil Research Articles

Optimisation of Vacuum Distillation Units in Oil Refineries Using Surrogate Models

To ensure the optimum performance of downstream processes in a petrochemical refinery, the operation of a vacuum distillation unit (VDU) is critical. It needs to satisfy the yield and quality requirements of the downstream process. Otherwise, it will result in a loss of profitability in the refinery. Hence, it is important to optimise the operation of the VDU to ensure optimum performance. Traditionally, VDU is operated within the design envelope, and its operation condition is fine-tuned based on the operator’s experience. However, such action does not guarantee the optimum performance of the entire refinery as it only considers the operation of VDU without understanding the effects towards downstream processes. Therefore, this work presents a framework to optimise VDU operations with consideration of the downstream processes. The framework consists of process simulation, surrogate modelling, and multi-objective optimisation. The developed framework aims to determine trade-offs between high vacuum gas oil (HVGO) yield and total annualised cost (TAC) of a refinery that considers the needs of downstream operations. In this work, crude oil blending ratio, furnace outlet temperature, flash zone temperature, column top pressure, column bottom pressure, stripping steam flowrate, HVGO pump-around flowrate, and light vacuum gas oil (LVGO) pump-around flowrate of the VDU are to be optimised. Based on the optimised result, the heavy-light crude blend achieves higher HVGO yield and lower TAC, and the optimised results were validated with the simulation results via Aspen HYSYS. The proposed methodology was proven to have accurate estimations of the VDU operation in the process simulation environment. Moreover, the optimised results can provide insight into the optimal process conditions of VDU for the refiners. With this insight, effective operating strategies can be developed to overcome the limitations present in real VDU operations.

Oxidative desulfurization of VGO using carbon nanostructures created by NTP-pyrolysis of fuel oil

Desulfurization of heavy oil fractions is complicated due to the high content of stable polycyclic systems including thiophene ring. Therefore, there is a need to develop new efficient and cost-effective desulfurization methods. The catalytic activity of carbon structures obtained by plasma-chemical pyrolysis of hydrocarbon feedstock (fuel oil, non-hydrorefined vacuum gas oil and catalytic cracking residue) was investigated in this work. The catalytic activity of carbon structures was investigated in relation to the process of oxidative desulfurization of light vacuum gas oil. The oxidation process was carried out at 60°C using ultrasonic dispersion for 1 minute. The oxidation products were extracted with furfural. As a result of oxidation followed by extraction, the sulfur content in gas oil decreased from 0.64 to 0.24% wt.

Thermodynamic Modeling and Process Simulation of Kumkol Crude Oil Refining

The Crude Distillation Unit (CDU) mechanism is commonly regarded as the first stage in petroleum refining. In this study, Aspen Plus® is used to simulate the basic process of a CDU, which consists of an Atmospheric Distillation Column (ATC) and a Vacuum Distillation Column (VC). These columns are fed with two types of crude oil: KUMKOL from Kazakhstan and Soviet Export Blend, in the proportions of 0.75:0.25, 0.50:0.50, and 0.25:0.75, respectively. The goal was to do a parametric analysis and analyze the resultant streams of naphtha, kerosene, Atmospheric Gas Oil (AGO), Light Vacuum Gas Oil (LVGO), and Heavy Vacuum Gas Oil (HVGO). The simulation used the CHAO-SEA thermodynamic model, which included the Chao-Seader correlation, the Scatchard-Hildebrand model, the Redlich-Kwong equation of state, the Lee-Kesler equation of state, and the API gravity technique. Temperature, pressure, mass flow, enthalpy, vapor percentage, and average molecular weights of the streams at various phases within the CDU system were estimated. For both the ATC and VC columns, curves indicating Temperature- Pressure vs the number of stages, as well as ASTM D86 (temperature) versus stream volume % distillation, were developed. The results show that when compared to feed streams containing 0.25 and 0.50 StdVol of Kumkol Kazakhstan Oil, the feed stream with 0.75 StdVol produces more Heavy, Medium, and Light Vacuum Gas Oil (H-VGO, M-VGO, and L-VGO), as well as more Vacuum Gas (VG). These findings indicate that Kumkol Kazakhstan Oil is of high quality and has fewer contaminants, such as sulfur when compared to other accessible mixes throughout the world.

Revamping Fluid Catalytic Cracking Unit, and Optimizing Catalyst to Process Heavier Feeds

H-Oil gas oils have a higher density and higher nitrogen content, and consequently much lower reactivity than straight-run vacuum gas oils during fluid catalytic cracking (FCC). The conversion of H-Oil gas oils observed in a laboratory catalytic cracking unit at constant operating conditions showed a 20 wt.% lower conversion rate than straight-run hydrotreated vacuum gas oil. Thus, a revamp of commercial FCC units, and the selection of a higher activity catalyst with lower coke selectivity is needed to provide the stable trouble-free operation of the unit. The performed revamp of the commercial FCC unit allowed a stable operation at a higher throughput. It also allowed an increased riser outlet temperature from 532 to 550 °C; increased maximum allowable regenerator temperature from 705 to 730 °C; decreased afterburning from 12 to 6 °C; decreased NOx emissions in the flue gas from 250 to 160 mg/Nm3; improved catalyst regeneration; decreased catalyst losses to 0.0142 kg/t feed; and improved catalyst circulation at a higher throughput. It was confirmed in the commercial FCC unit that the H-Oil light vacuum gas oil is the least reactive H-Oil gas oil during catalytic cracking.

Feasibility study of the preparation of RFO from deasphalted pitch

Crude oil is fractionated into different products as it is composed of thousands of different compounds having different boiling points. Crude oil is generally described as sweet, sour, light, and heavy crude. This nature of crude decides its processing in the refinery. In a typical petroleum refinery, the refinery design is based on the crude potential and the targeted product. The upgradation of petroleum pitch is a versatile challenge since ever. There are several approaches used to upgrade petroleum pitches. Several known methods are solvent deasphalting, visbreaking, delayed coking, and bitumen making. Solvent deasphalting is important as it is used to make lubricating oil of different grades and wax. The primary purpose of SDA is to decrease the metal content and waxes (paraffin) in the deasphalted asphalt. This approach overall increases the insoluble metals and reduces the oil in asphalt, and thus, up-gradation of asphalt becomes difficult further. This paper describes the upgradation of deasphalted pitch to make fuel oil of different viscosity grades using Kero, light vacuum gas oil, and light cycle oil as cutter stocks. In this study, it had been tried to make fuel oil as per IS 1593: 2018. The detailed study showed that when the deasphalted pitch is blended with cutter stocks, it resulted in fuel oil of different grades. The study also showed the effect of addition kero on the calorific value. This study clearly defines why Kero was not suitable for the formation of fuel from deasphalted pitch based on high-resolution mass spectroscopy (HRMS). HRMS analysis showed that kero fraction contains maximum saturates 75.1 % while light cycle oil contains maximum aromatics 59.8 %. Finally, the study showed that why light cycle oil is found suitable for the preparation of fuel from deasphalted aromatics pitch. ASTM D 6730 also confirms the non-suitability of kero fraction to prepare fuel oil and support the HRMS data.

Impact of hydrogenation on miscibility of fast pyrolysis bio-oil with refinery fractions towards bio-oil refinery integration

In particular, a straw-based Ablative Fast Pyrolysis (AFP) oil was upgraded via hydrotreatment (HDT) in order to be used as a blending component with fossil-based intermediates. The raw pyrolysis oil is characterized by H/C = 0.14, O/C = 0.58 and C = 57.73 wt%, while the HDT pyrolysis oil has a H/C = 0.14, O/C = 0.016 and C = 85.85 wt%. Based on the density, viscosity and composition, and in association with a typical refinery, the possible petroleum refinery entry points for HDT pyrolysis oil include Straight Run Gas-Oil (SRGO), Atmospheric Gas-oil (GO), Fluid Catalytic Cracking Light Cycle Oil (LCO) and Heavy Cycle Oil (HCO), as well as Light Vacuum Gas-Oil (LVGO). To that aim, this work examined raw and HDT bio-oil blends with the aforementioned candidate petroleum streams at a 30:70 v/v ratio (raw or HDT bio-oil/petroleum stream) with respect to their miscibility, by comparing the blend components’ properties, microscopic observation, and interfacial tension analysis. From the microscopic observation, the addition of HDT pyrolysis oil in all examined petroleum candidates renders a homogeneous mixture where the two phases cannot be distinguished. In addition, no interfacial tension was observed in the examined blends, while the blend of HDT pyrolysis oil with the different petroleum streams not only did not deteriorate the fuel characteristics over the original petroleum stream, but also it improved them, in some cases. In general, the HDT pyrolysis oil was found to be miscible with all the examined refinery streams, extending the potential further investigation of stabilized pyrolysis oil integration over oil refineries.

ОЦЕНКА ВОЗМОЖНОСТИ ПОЛУЧЕНИЯ РАСТВОРИТЕЛЯ С НИЗКИМ СОДЕРЖАНИЕМ АРОМАТИЧЕСКИХ УГЛЕВОДОРОДОВ В АО «АНХК»

. In connection with the emerging demand for gasoline solvent with a low content of
 aromatic hydrocarbons we carrier out the analysis of intermediate products obtained in JSC " ANHK " 
 suitable for the producing of the solvent. The most suitable for the separation of the fraction are gaso line fractions producing from the hydrogenation product of the hydrocracking of light vacuum gas oil 
 and the hydrogenation product of high conversion hydrogenation of the heavy middle distillate frac tions. We performed work on the recovery of a narrow fraction of gasoline solvent and its tests for 
 compliance with the requirements.

Role of Catalyst in Optimizing Fluid Catalytic Cracking Performance During Cracking of H-Oil-Derived Gas Oils

Three H-Oil gas oils, heavy atmospheric gas oil (HAGO), light vacuum gas oil (LVGO), heavy vacuum gas oil (HVGO), and two their blends with hydrotreated straight run vacuum gas oils (HTSRVGOs) were cracked on two high unit cell size (UCS) lower porosity commercial catalysts and two low UCS higher porosity commercial catalysts. The cracking experiments were performed in an advanced cracking evaluation fluid catalytic cracking (FCC) laboratory unit at 527 °C, 30 s catalyst time on stream, and catalyst-to-oil (CTO) variation between 3.5 and 7.5 wt/wt The two high UCS lower porosity catalysts were more active and more coke selective. However, the difference between conversion of the more active high UCS lower porosity and low UCS higher porosity catalysts at 7.5 wt/wt CTO decreased in the order 10% (HAGO) > 9% (LVGO) > 6% (HVGO) > 4% (80% HTSRVGO/20% H-Oil VGO). Therefore, the catalyst performance is feedstock-dependent. The four studied catalysts along with a blend of one of them with 2% ZSM-5 were examined in a commercially revamped UOP FCC VSS unit. The lower UCS higher porosity catalysts exhibited operation at a higher CTO ratio achieving a similar conversion level with more active higher UCS lower porosity catalysts. However, the higher UCS lower porosity catalysts made 0.67% Δ coke that was higher than the maximum acceptable limit of 0.64% for this particular commercial FCC unit (FCCU), which required excluding the HVGO from the FCC feed blend. The catalyst system containing ZSM-5 increased the LPG yield but did not have an impact on gasoline octane. It was found that the predominant factor that controls refinery profitability related to the FCCU performance is the FCC slurry oil (bottoms) yield.

Functional influence of depressor and depressor-dispersant additives on marine fuels and their distillates components

The influence of depressant and depressant-dispersing additives injection in the amount of less than 0.75% on low-temperature properties of marine fuels and their distillate compounds is presented in this research paper. As tested components were used the following industry-derived components: hydrotreated straight-run diesel fraction (HSRDF), ultra-low sulfur content hydro-creaking diesel fuel (ULSDH), light gas oil delayed coking and light gas oil catalytic creaking (LGODC and LGOCC), light vacuum gas oil (LVGO) and visbreaker residue (VR). As marine fuels samples the compounds based on described above components were used. The influence of the following additives was studied: SEVILEN 11606-40, KOLTEK DN 3149, Dodiflow 5934 and DPN-172.

Study on phase behavior and properties of binary blends of bio-oil/fossil-based refinery intermediates: A step toward bio-oil refinery integration

To defossilize the current liquid energy backbone a sustainable renewable substitute for fossil crude oil is required. The long–term aim is to increase the co-feed of renewables beyond the current level. However, technical constrains and certain properties limit the conventional biogenic co-feed level to less than 10%.The potential of identifying refinery compatible entry points to directly co-feed bio-based refinery intermediates and further co-process in existing petroleum crude oil refineries is investigated in the current study. The studied pyrolysis bio-oil has been upgraded via mild hydrotreatment (HDT) in order to fulfil specifications and become a “drop-in” biofuel in compatible refinery “location”. The properties of HDT-Bio-oil as well as fossil-based refinery intermediates were compared and five fossil-based refinery intermediates have been concluded as potential candidates for co-processing. The miscibility of the aforementioned renewable and conventional fuels has been investigated. Among all refinery streams, Fluid Catalytic Cracking Light Cycle Oil (FCC LCO) and secondly Light Vacuum Gas Oil (LVGO) have been concluded to be the most promising candidates for co-processing, resembling HDT-Bio-oil’s properties.

A Comparative study between MPC and PI controller to control vacuum distillation unit for producing LVGO, MVGO, and HVGO

This study describes the selection of controllers in the vacuum distillation unit (VDU) between a model predictive control (MPC) and a proportional-integral (PI) controller by comparing the integral square error (ISE) values. Design of VDU in this simulation is based on modified Metso Automation Inc. scheme. Controlled variables in this study are feed flow rate, feed temperature, top stage pressure, condenser level, bottom stage temperature, LVGO (light vacuum gas oil), MVGO (medium vacuum gas oil), and HVGO (heavy vacuum gas oil) flow rate. As a result, control performance improvements occurred as using MPC compared to PI controllers, when testing a set-point change, of feed flow rate control, feed temperature, top-stage pressure, bottom-stage temperature and flow rate of LVGO, MVGO, and HVGO, respectively, 36%, 6%, 92%, 53%, 90%, 96% and 88%. Only on condenser level control PI performs much better than the MPC. So PI controller is used for level condenser control. While for the test of disturbance rejection, by changing feed flow rate by 10%, there is improvement of control performance using MPC compared to PI controller on feed temperature control, top-stage pressure, bottom-stage temperature and flow rate LVGO, MVGO and HVGO 0.3%, 0.7%, 14%, 2.7%, 10.6% and 4.3%, respectively.

Effectivity of Phenol during Solvent Extraction of a South African Bituminous Coal under Mild Conditions

Solvent extraction of a South African bituminous coal was carried out under mild conditions (<400 °C) with a holding time of 20 min and an initial nitrogen (N2) pressure of 6 MPa. Thermal degradation of coal with phenol results in the depolymerization of the coal, yielding coal-derived liquids and insoluble residues. The effectiveness of phenol for solvent extraction of coal within the temperature range of 300–360 °C was investigated, with a focus on the quality of the coal-derived liquids. It was found that an increase in temperature from 300 °C to 360 °C resulted in an increase in the conversion and yields of both oil and gas, and a reduction in the intermediate components (preasphaltenes + asphaltenes, PAAs). The conversion and extraction yields of hexane-soluble (HS) oils were 49.5% (daf) and 26.3% (daf), respectively (daf = dry ash-free), for thermal depolymerization reactions at 360 °C. It seems that the extraction process dissolves molecular fragments of the coal, because the infrared spectra of the coal and the extraction products are similar. The SimDis results of the coal-derived liquids (300–360 °C) indicated that the samples consisted of light vacuum gas oil (23–31 wt %), distillate fuel oil (16–30 wt %), heavy vacuum gas oil (18–34 wt %), and residual oil (3–16 wt %). These results show the potential of phenol as a solvent to extract South African bituminous coal at mild temperatures for value-added liquid fuels and add to the general knowledge of the potential utilization of the Permian-aged South African bituminous coals.

Untreated and HNO3-treated pyrolysis char as catalysts for pyrolysis of waste tire: In-depth analysis of tire-derived products and char characterization

The pyrolysis char produced in the pyrolysis of scrap tire rubber has few market outlets, reducing the economic viability. Thus, the char properties was firstly studied in this work, and then untreated and 5M HNO3-treated chars were investigated for their potentials as the catalysts for pyrolysis of waste tire. The product distribution and the quality of tire pyrolysis oil were examined. The gas products were analyzed by using GC/FID whereas the oil products were analyzed by using SIMDIST-GC and GC×GC/TOF-MS. Sulfur and nitrogen contents were determined by using CHNS-analyzer. The catalysts were also characterized by using BET, XRD, XRF, FTIR, FE-SEM, and TG/DTA. The results indicated that the surface area and pore size of treated char were enhanced by the acid treatment. Furthermore, it can be noted that the increase in the total acidity of treated char was caused by the enhancement of carboxyl (-COOH) group on the surface. Additionally, the treatment using 5M HNO3 can demineralize and significantly reduce sulfur content in the char. When employed as a catalyst, the HNO3-treated char increased the gas production due to its enhanced acidity, surface area and pore size, consequently promoting the greater cracking activity. However, both untreated and treated chars dramatically decreased gas oil, light vacuum gas oil, and heavy vacuum gas oil, leading to the drastic enhancement of gasoline and kerosene. Moreover, even though the char catalysts cannot reduce nitrogen content in oil, they can greatly remove sulfur in oil (approximately 26.6–27.3%). Nevertheless, the untreated char that contained a larger content of elements or minerals than the treated one gave significantly higher petrochemical production, which indicates that deminerization by the acid treatment may not always be needed for better activity, especially for petrochemical production.

Economic Model Predictive Control (EMPC) of an Industrial Diesel Hydroprocessing Plant

Diesel hydroprocessing is a refinery process by which the sulfur impurities are removed by hydrodesulfurization and the main product diesel is obtained by hydrocracking. The industrial Diesel Hydroprocessing Plant considered in this study consists of two hydrodesulfurization reactors and one hydrocracking reactor in series. The feed to the plant is a blend of four different raw material streams which are heavy diesel (HD), light diesel (LD), light vacuum gas oil (LVGO) and imported diesel from another refinery. A two-layer, hierarchical Economic Model Predictive Control (EMPC) structure is proposed to maximize the profit of the plant. The plant-wide profit is maximized by computing the optimal set-points by the upper economic model predictive control layer while these set-points are tracked by the regulatory model predictive controllers in the lower level. Set-point tracking and disturbance rejection performances of the proposed EMPC structure are tested through closed-loop simulations.

Liquefaction of Lignocellulose in Fluid Catalytic Cracker Feed: A Process Concept Study

We report a process concept for lignocellulose liquefaction in a refinery stream that will be coprocessed with the resulting biocrude and that, therefore, does not require the recovery and recycling of the liquefaction solvent. Light cycle oil and vacuum gas oil were found to be the two most promising solvents. Both refinery streams could provide a liquid yield of 58 C % (64 % energy yield). A techno-economic assessment indicates that the biocrude could be produced at an energy-equivalent crude oil price of 51-64 $ per barrel at a wood cost of 85 $ per dry ton.

Upgrading of Waste Tyre-Derived Oil from Waste Tyre Pyrolysis over Ni Catalyst Supported on HZSM-5 Zeolite

The catalytic pyrolysis of waste tyre was investigated using Ni-doped HZSM-5 zeolite as a catalyst in a bench-scale reactor ramped from room temperature to 500 °C (pyrolysis zone) and 350 °C (catalyst bed), aiming to improve the quality of tyre-derived oil in terms of sulphur reduction and enhancement of valuable petrochemical production. 5 wt% of nickel was introduced on HZSM-5 zeolite using incipient wetness impregnation, and characterised using XRD, surface area analyser, and XPS. Gaseous products were analysed by GC-FID. The GCxGC-TOF/MS and SIMDIST-GC were used for analysis of pyrolysis oil. The sulphur content in tyre-derived oil was determined by S-analyser. The introduction of metallic nickel on HZSM-5 zeolite significantly changed textural properties, also modified the catalytic behaviour. When compared to parent HZSM-5 zeolite, Ni/HZSM-5 catalyst significantly improved gasoline and kerosene production in waste tyre-derived oil, whereas the heavy fractions, such as gas oil and light vacuum gas oil, drastically decreased. In addition, Ni doping drastically reduced sulphur contents in tyre-derived oil by 29.2%. Benzothoiphenes, dibenzothiophenes, and naphthothiophene were the sulphur species that significantly decreased. Furthermore, with Ni loading, the production of cumene, ethylbenzene, toluene, and mixed xylenes in oil was also enhanced. These results indicated Ni/HZSM-5 was a promising catalyst for enhancement of tyre-derived oil quality.

Vacuum Gas Oil Hydrocracking on NiMo/USY Zeolite Catalysts. Experimental Study and Kinetic Modeling

A bench-scale experimental unit based on a Robinson–Mahoney reactor with completely mixed gas and liquid phases was used to study the hydrocracking of a light vacuum gas oil on two base metal sulfide containing acid catalysts, characterized by their textural properties, NH3-TPD and pyridine-adsorbed Fourier-transformed infrared (Py-FTIR) acidity. The reactor effluent was analyzed in great detail by means of online gas chromatography and gas chromatography–mass spectrometry which evidenced the role of the catalyst acidity. The detailed analysis allowed the reaction scheme to be expressed at the level required by the kinetic analysis in terms of the fundamental Single Event Kinetics approach and thus drastically reduce the number of independent kinetic parameters to be determined from the experimental data. Reactor simulations illustrate the detailed predictions made possible by this approach.

Co-processing of vacuum residue/fraction oil blends: Effect of fraction oils recycle on the stability of coking feedstock

Thermal treatment and pyrolysis of vacuum residue/fraction oil blends have been conducted to quantitatively study the effect of the fraction oils recycle (i.e. the composition and the ratio of recycled fraction oils) on the stability of blends. The thermal treatment was completed in a static autoclave and the pyrolysis was run at 500°C according to a standard test (i.e. the MCR test, ASTM D4530). The pyrolysis coupled with the polarized light microscopic observation of the coke products provided a quantitative and convenient method for predictive assessment of the stability of a given feed. It was strongly suggested that atmospheric gas oil distillate (AGO) was not conducive to the stability of blends. The recycle ratio of AGO and light vacuum gas oil distillate (LVGO) had better be confined to around 0.1 and the valid upper limitation of recycle ratio for heavy vacuum gas oil distillate (HVGO) could be increased up to 0.6 for the purpose of digesting ill-processable vacuum gas oil fraction (VGO). It was concluded that appropriate selection of recycled fraction and ratio might not only favor the improvement of coking products distribution and the process capacity debottleneck, but also be beneficial for maintaining the stability of coking feedstock, suppressing asphaltenes-involved phase separation in the exchanger sections at high temperature, and consequentially favor the operation period extending of coking plants.

Modified HZSM-5 as FCC additive for enhancing light olefins yield from catalytic cracking of VGO

HZSM-5 with varying Si/Al2 ratios were modified with Mn and alkaline treatment and tested as FCC catalyst additives to enhance the yield of light olefins (in particular, propylene) from catalytic cracking of hydrotreated Arab Light vacuum gas oil (VGO). The performance of the Mn/HZSM-5 and alkaline treated HZSM-5 additives were assessed using a commercial equilibrium USY FCC catalyst (E-Cat) in a fixed-bed micro-activity test unit at 550°C and various catalyst/oil ratios. The yield of light olefins over E-Cat containing parent HZSM-5 increased to 18.1, 25.4 and 27.4wt% for Si/Al2 of 30, 80 and 280, respectively, compared with 15.4wt% over E-Cat (at 75wt% conversion). Further increase in light olefins yield was achieved upon using Mn modified HZSM-5 as an additive. The highest light olefins yield of 29.2wt% was achieved over E-Cat-Mn/HZSM-5 (Si/Al2=80, 2.0wt% Mn). The enhanced production of light olefins over the Mn/HZSM-5 additive is mainly attributed to the decrease in the acid density and the amount of strong acid sites, and (possibly) the partial narrowing of ZSM-5 micropore. Alkaline treated HZSM-5 also exhibited high light olefins yield compared with parent HZSM-5, due to the formation of hierarchical micro-meso topology. The highest light olefins yield of ∼28.3wt% was obtained over E-Cat-containing alkaline treated HZSM-5 (Si/Al2=80–280, using the appropriate desilication conditions).

Nitrogen Compound Conversion and Distribution in Liaohe Atmospheric Residue during Slurry-Bed Hydrocracking

The nitrogen compounds in Liaohe atmospheric residue (LHAR) have been analyzed through Fourier transform infrared spectroscopy (FTIR), gas chromatography coupled with mass spectrometry (GC–MS), etc. to investigate the mechanism of reaction during slurry-phase hydrocracking. Their chemical structures have been exploited, and the experiment data revealed that the molecular weight of nitrogen compounds after hydrocracking was increased in comparison to that in crude oil in the same fraction. Basic nitrogen compounds in Liaohe light vacuum gas oil (VGO) were composed of quinolines, etc., and non-basic nitrogen compounds consisted of carbazoles, amines, etc. The contents of basic nitrogen compounds were decreased with the increase of the boiling point, but non-basic nitrogen compounds changed oppositely. Meanwhile, nitrogen compounds could be hydrocracked, and the products were transferred into some “lighter” fractions, such as diesel and VGO.