Table of Content

12 May 2024, Volume 55 Issue 5

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DEVELOPMENT AND APPLICATION OF KEY TECHNOLOGIES FOR EFFICIENT LCO HYDROCRACKING AND HYDROUPGRADING

2024, 55(5):  1-7. 

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The efficient processing of typical macromolecular aromatic hydrocarbons in light cycle oil (LCO) has always been one of the keys to improve enterprise economic efficiency. Based on the chemical reaction network of macromolecular aromatics in LCO, through the integrated innovation of catalytic materials, process technology and reaction engineering, SINOPEC Research Institute of Petroleum Processing Co. Ltd. has successively developed the medium pressure hydro-upgrading technology (MHUG) and LCO hydrocracking to produce gasoline with high octane or aromatics technology (RLG). MHUG technology can process inferior raw materials such as LCO and coking diesel, and the clean vehicle diesel with high cetane number can be obtained through aromatics hydrogenation saturation and ring opening reaction. RLG technology can process LCO and C₉/C₁₀+ heavy aromatics, and the high-octane gasoline blending components or BTX extracts can be obtained through aromatics selective hydrogenation saturation, selective ring opening, and side chain break reaction. The development and application of the platform technology provides strong technical support for LCO upgrading, oil-to-chemicals, reducing the ratio of diesel to gasoline, and improving economic benefits.

SIDE-STREAM TEST AND COMMERCIAL APPLICATION OF FLEXIBLE FILTER TECHNOLOGY FOR FCC SLURRY

2024, 55(5):  8-13. 

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FCC slurry filtration test was carried out in the 5 kt/a side-stream test unit using the remove solid flexible filter (RSFF) technique in Shanghai Petrochemical Corporation. The results showed that the yield of the de-solid slurry was about 90% and the mass fraction of (Al+Si) in the de-solid slurry was about 10 μg/g. The particle size smaller than 1 μm could be effectively removed by RSFF technology. In the initial stage of filtration, the filtration pressure difference rose rapidly and then slowly. The inflexion of filtration pressure difference had a positively correlation with the feed flow rate. Based on the above results, an industrial application test was carried out in a 300 kt/a unit of Maoming Wailian Petrochemical Company. The results showed that the average yield of the de-solid slurry was over 92%, the ash content in the de-solid slurry was less than 100 μg/g, and the ash removal rate was about 98%. RSFF technology does not need a lot of material circulation and has low wear to equipment. It is suitable for processing slurry directly from FCC unit and even purchased slurry.

DEVELOPMENT AND APPLICATION OF AROMATICSEXTRACTION AND DISTILLATION PROCESS (SED-BTX)

2024, 55(5):  14-19. 

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A new process for aromatics extraction and distillation (SED-BTX) of hydrogenated catalytic cracking gasoline was developedby establishing a comprehensive phase equilibrium data package and process simulation system. This process takes extraction distillation as the core, combines extraction distillation and liquid-liquid extraction organically, and makes use of their respective advantages to achieve the goals of energy conservation and carbon reduction, as well as high recovery rate and high purity of BTX products. The SED-BTX process was successfully applied to a 350 kt/a industrial plant in one run. The results showed that the yield and purity of benzene product reached 99.9% and 99.99% respectively, that of toluene product reached 99.9% and 99.98% respectively,the non-aromatic content in the raffinate oil was over 99.3%, and the sulfolane content was less than 1 μg/g. The comprehensive energy consumption of the whole unit including the distillation unit was 56.6 kgOE/t（1 kgOE=41.8 MJ）, which was 25% lower than the traditional liquid-liquid extraction process.

COMMERCIAL APPLICATION OF LIQUID-PHASE HYDROGENATION PROCESS USING TUBULAR REACTORS FOR REFORMATE

2024, 55(5):  20-25. 

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In response to the problems of insufficient refining depth, high yield of heavy component, fast deactivation of clay, and complex processand high energy consumption of xylene hydrogenation system in a 1.0 Mt/a continuous catalytic reforming unit of a petrochemical company, the reformate was treated withthe liquid phase hydrogenation process (FITS process) developed by SINOPEC Changling Company and Hunan Changling Petrochemical Technology Development Co., Ltd.. The process makes use of hydrogen nano-pore dispersion technology to make hydrogen evenly dispersed in the oil phase, and can effectively remove olefins from reformate.The bromine index of benzene product is lessthan 20 mgBr/(100g), and that of mixed xylene product is less than 50 mgBr/(100g). The successful application of FITS process could eliminate clay tank for benzene refining and xylene hydrogenation unit, and greatly reduce the energy consumption and operating costs of aromatics treatment unit.

PROBLEM ANALYSIS AND TECHNICAL REFORM OF OVERFLOW COKE COOLING PROCESS IN DELAYED COKING UNIT

2024, 55(5):  26-30. 

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In order to solve the environmental problem of high content of volatile organic compounds（VOCs） in coke cooling hot water tank caused by oil entrainment of coke cooling water during overflow coke cooling process of 1.2 Mt/a delayed coking unit in a petrochemical company,the overflow coke cooling process was transformed into coke soaking coke cooling process.By adding a steam extractor on the evaporator line at the top of the reflux tank of the contact cooling drum, the steam and oil gas generated in the coke cooling process of the coke drum were pumped to the fractionation system, and the heat in the coke layer was removed by utilizing the vaporization latent heat of the coke cooling water, so as to achieve coke soaking and coke cooling in the coke drum. The coke cooling time of the coke drum could reach the water discharging condition within 12 h after the process of coke soaking coke cooling was completed and put into operation, which had no impact on the production cycle of the unit. During coke cooling, the mass concentration of VOCs in the top of hot water tankdecreased from 352.8 mg/m³ to 1.6 mg/m³，the mass concentration of oil in the coke cooling water decreased from 20-70mg/L to 1-10mg/L.The decrease of 30 m³/d in the waste oil tank indicated that more oil and gas in the coke process were recovered to the fractionation system, thus reducing the oil and gas carried out with the cold coke water. The steam energy consumption of 1.0MPa steam increased by 4.13 MJ/t, the electrical energy consumption decreased by 2.04 MJ/t, and the total energy consumption increased by 2.09 MJ/t, which had little impact on the energy consumption of the unit. The volatile of petroleum coke increased slightly, which could meet the index requirements. The problemof environmental protection existing in the original overflow coke cooling process was solved, and the environmental operation of the unit was realized after the coke soaking coke cooling process was adopted in the coke drum.

PRACTICE OF 4.0 Mt/a HYDROCRACKER FOR INCREASING HEAVY NAPHTHA PRODUCTION USING NAPHTHENE-BASED FEED

2024, 55(5):  31-37. 

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The 4.0 Mt/a hydrocracker of CNOOC Huizhou Petrochemical Company Limited was modified by using RN-410C/RHC-210/RHC-220 graded catalysts and fractionation system revamping to upgrade the production of high-quality chemical feedstocks. The calibration results show that using the VGO feedstock, blended with 20.16% of CGO, with the nitrogen mass fraction of 0.1846% and a density (20 ℃) of 0.910 g/cm³, under the conditions of an inlet pressure of 15.18 MPa, an average hydrotreating temperature of 385.6℃ and average hydrocracking temperature of 389.3℃, the hydrogen consumption is 2.98%, heavy naphtha yield is 35.23%, and tail oil yield is 10.69%. The naphtha, jet fuel, and diesel products can meet the specification requirements. The smoke point of jet fuel can reach 30 mm, the cetane index of diesel with 1% of polycyclic aromatics, can reach 72.3, and the BMCI value of tail oil is 12. The energy consumption of the unit is 21.91 kgEO/t(1 kgOE=41.8 MJ), reaching the advanced level of similar units. The selectivity of heavy naphtha increased from 77.3% in the previous cycle to 84.2% in this cycle, indicating a significant effect of catalyst gradation and reaction zone regulation.

DEVELOPMENT AND COMMERCIAL APPLICATION OF HYDROCRACKING CATALYST RCF-1 FOR FISCHER-TROPSCH SYNTHETIC OIL

2024, 55(5):  38-44. 

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In order to process Fischer-Tropsch (F-T) synthetic oil, on the basis of optimizing the acidic component of the catalyst to improve the temperature sensitivity of the catalyst and selectingthe suitable mesoporous silica-aluminum components, catalyst RCF-1 for isomerization-hydrocracking of F-T wax was developed,which had low temperature sensitivity and high selectivity of middle-distillate. Based on this catalyst, the low-temperature F-T hydrotreating and hydrofinishing CFH^L technology was employed. The commercial application of the catalyst RCF-1 showed that the cetane number and freezing point of the diesel distillate produced by the isomerization-hydrocracking unit were 76 and -33 ℃, respectively,using the low-temperature process for the hydrogenation of F-T synthetic CFH^L.The stabilization-hydrogenation and isomerization-hydrocracking naphtha fractions are particularly suitable as steam cracking feed.

STUDY ON THE PERFORMANCE OF Mn/Cr₂O₃ CATALYSTS FOR CATALYTIC OXIDATION OF TOLUENE

2024, 55(5):  45-52. 

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In order to improve the inefficiency of volatile organic compound (VOCs) combustion processing, Cr₂O₃ nano-particles were prepared by using a hydrothermal synthesis method and subsequently used as carrier to load manganese through impregnation method, leading to the development of a series of Mn/Cr₂O₃ catalysts. The physical and chemical properties of the catalysts were characterized, and the catalytic oxidation performance for toluene was evaluated. The corresponding results indicated that the introduction of MnO_x onto Cr₂O₃ not only instigated the creation of an organized mesoporous structure within the chromium-based support, but also markedly increased the specific surface area. This enhancement facilitated the dispersion of active MnO_x, maintained the stable structure of Mn/Cr₂O₃ catalysts, and resolved the issue of aggregation-induced deactivation of the active components. When Mn content was 20%, Mn/Cr₂O₃ catalyst exhibited the highest activity, and the temperature for the toluene conversion reaching 50%, 90% and 100%, were 210, 229 and 240 ℃, respectively. Moreover, the toluene conversion could be maintained at 100% at 240 ℃ in 50 h stability test. The results demonstrated that by controlling the amount of Mn species incorporated, it was possible to effectively modulate the pore structure of the Mn/Cr₂O₃ catalysts, the interactions between the metal and support and the ability to eliminate coke deposition.

PERFORMANCE OF ALKALI-TREATED HY ZEOLITE SUPPORTED Co-BASED CATALYST FOR FISCHER-TROPSCH SYNTHESIS

2024, 55(5):  53-57. 

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A series of Co/HY-X catalysts for Fischer-Tropsch synthesis were prepared by melting method on HY zeolites treated with different quaternary ammonium bases. The effects of different ammonium-alkaline-treated HY zeolite on Fischer-Tropsch synthesis catalysts performance were investigated. The catalysts were characterized by nitrogen physical adsorption-desorption, X-ray diffraction, Fourier transform infrared spectrum and ammonia temperature-programmed desorption, and the catalytic performance of the catalysts for Fischer-Tropsch synthesis was tested in a high-pressure fixed bed reactor. The results showed that the conversion rate of CO increased by about 30 percentage points on the catalyst treated with tetramethylammonium hydroxide, compared with that of Co-HY without treatment.

EFFECT OF ZEOLITE-MODIFIED COPPER-SILICON CATALYST ON SELECTIVE HYDROGENATION OF MALEIC ANHYDRIDE

2024, 55(5):  58-66. 

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In this paper, the effects of ZSM-5, MOR, 4A and 5A zeolites on the selective hydrogenation of maleic anhydride over copper-based catalysts were investigated by using ammonia evaporation method to treat CuSi catalysts. The results showed that the dispersion of copper particles in CuSi-4A catalyst was poor, which resulted in a small specific surface area; the adsorption capacity of H₂ on CuSi-4A catalyst was the weakest, and the activity of CuSi-4A was significantly lower than that of CuSi-MOR, CuSi-ZSM-5 and CuSi-5A catalysts. The CuSi-MOR catalyst was rich in Cu⁺, and the copper particles were smaller. Under the reaction conditions of a temperature of 280 ℃, a molar ratio of hydrogen to anhydride of 79 and a WHSV of 0.12 h^-1, the maleic anhydride conversion rate was as high as 99.6%, and the selectivity of γ-butyrolactone anhydride was 47.9%. Compared with CuSi catalysts without zeolite doping, the catalytic activity was significantly lower than that of the zeolite doped catalysts. Therefore, the use of zeolite as part of the silicon source in the process of preparing catalyst by ammonia evaporation can provide certain reference for improving metal dispersion and catalyst design.

PREPARATION OF IN-SITU CRYSTALLIZATION TYPE CATALYTIC CRACKING CATALYST BY INTRODUCING Y ZEOLITE SEED SOLUTION TO PREFORM KAOLIN MICROSPHERES

2024, 55(5):  67-72. 

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NaY/kaolin composite microspheres were prepared by in-situ crystallization of kaolin microspheres after introducing Y zeolite seed solution in the preforming process, and it was characterized by X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), N2 adsorption-desorption at low temperature and scanning electron microscopy (SEM). XRF and XRD showed that compared with conventional methods, the silicon aluminum ratio of NaY/kaolin composite microspheres prepared by introducing seed solution increased from 1.61 to 1.70, and the crystallinity of Y zeolite increased from 21% to 29%. N₂ adsorption-desorption characterization result showed that the specific surface area and pore volume of NaY/kaolin composite microspheres prepared by conventional methods were 311.8m²/g and 0.28cm³/g, respectively. After the introduction of seed solution, the specific surface area and pore volume increased to 521.8m²/g and 0.41cm³/g, respectively, and the mesoporous distribution increased from 4-25 nm to 10-150 nm. The catalytic cracking test results of heavy oil showed that compared with conventional methods,the slurry yield over the in-situ crystallization catalyst prepared by introducing seed solution as additives decreased by 3.78 percentage points,the gasoline yield increased by 3.48 percentage points, and the total liquid yield increased by 3.11 percentage points.

PREPARATION OF ZINC-BASED ROOM TEMPERATURE DESULFURIZER BY CO-PRECIPITATION

2024, 55(5):  73-79. 

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Under the background of rapid development of polypropylene industry in China, sulfur, as a harmful impurity in the propylene polymerization, has a negative effect on the quality of polypropylene product and the normal operation of the plant, therefore, how to effectively remove harmful impurities such as sulfur in propylene has become a key problem. This study utilized the co-precipitation method, employing zinc nitrate hexahydrate [Zn(NO₃)₂.6H₂O] and aluminum chloride hexahydrate (AlCl₃.6H₂O) as the active component and carrier, respectively, with sodium carbonate (Na₂CO₃) as the precipitant, to successfully develop an efficient zinc-based room temperature desulfurizer. After single-factor experiments,the optimum conditions were determined as follows:a reaction temperature of 60℃,a molar ratio of zinc to aluminum of 4:1, a molar ratio of zinc and aluminum to precipitator of 1:1.3,a concentration of zinc salt of 0.75 mol/L and a calcination temperature of 300℃.The permeation capacity of the desulfurizer reached 22.69%. Further analyses revealed that the precursor of the desulfurizer was basic zinc carbonate. The optimum calcination temperature was 300 ℃, at which the desulfurization activity was the highest (penetration sulfur capacity was 22.69%) and the pore structure and properties were excellent (specific surface area of 67.63 m²/g, pore volume of 0.202 cm³/g, average pore diameter of 10.94 nm). The performance evaluation at 25℃showed that the desulfurizer exhibited excellent desulfurization effect, with a penetration time of 600 min and a penetration capacity of 23.17%.

THERMODYNAMIC ANALYSIS AND EXPERIMENTAL STUDY ON DEHYDROGENATION OF ISOPENTANE TO MONO-OLEFINS

2024, 55(5):  80-86. 

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The thermodynamic equilibrium parameters of the main dehydrogenation reactions of isopentane to various mono-olefinand theoretical equilibrium conversion of isopentane were calculated.The product distribution and the effects of temperature, pressure and molar ratio of hydrogen to hydrocarbon on the equilibrium were analyzed.Simultaneously, the impacts of different process conditions on the reaction performance and product distribution on the Pt-Sn-M/Al₂O₃ catalyst were investigated by experiments.The results showed that the most abundant olefin produced by isopentane dehydrogenation was 2-methyl-2-butene, followed by 2-methyl-1-butene, and the least was 3-methyl-1-butene. High temperature, low pressure and low molar ratio of hydrogen to hydrocarbon were favorable for dehydrogenation reaction, but high temperature would lead to increase of side reactions such as cracking, and decrease of the selectivity of olefin. However, low pressure and low molar ratio of hydrogen to hydrocarbon could accelerate the coke deposition rate of the catalysts. The actual conversion of isopentane dehydrogenation testwas lower than the thermodynamic equilibrium calculated by thermodynamics. By selecting suitable test conditions, the conversion of isopentane dehydrogenation could be close to the thermodynamic equilibrium, which verified the reliability of the thermodynamic analysis results.

STUDY ON CATALYTIC CRACKING REACTION PERFORMANCE OF PYROLYSIS OIL FROM WASTE PLASTICS

2024, 55(5):  87-95. 

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In order to realize the circular economy of plastics, the catalytic cracking reaction rule, product distribution and composition characteristics of pyrolysis oil from waste plastics were explored by using the catalyst CGP and DMMC-2, respectively. The results showed that the pyrolysis oil of waste plastics had good performance in the production of gasoline or/and the raw chemicals by catalytic cracking. When aiming at increasing gasoline production, the gasoline yield can reach 52.37%, and the liquefied gas yield is 19.01%, of which the propylene yield is 7.82%; when the production of raw chemicals is the goal, the total yield of low carbon olefins and benzene, toluene and xylene (BTX) can reach 47.82%, of which the ethylene, propylene and butane yield is 32.51% and the propylene yield is 16.67%, and the yield of BTX reaches 15.31%, in which xylene is the dominate. The research results can provide a guidance for the development of high-value utilization technology of waste plastic pyrolysis oil.

STUDY ON KEY COMPONENTS OF HYDROGENATED LCO CATALYTIC CRACKING FOR LIGHT AROMATICS PRODUCTION

2024, 55(5):  96-103. 

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A small-scale fixed fluidized bed (FFB) pilot plant was used to compare the potential oflight circulating oil (LCO)catalytic cracking for producing light aromaticsunder the conditions suitable for LCO hydrogenation, the key components of FCC light aromatics in hydrogenation of LCO were identified as cycloalkanes and non-indenylated monocyclic aromatics. Based on the result that the mass fraction of cycloalkanes in hydrogenated LCO was positively proportional to its contribution to light aromatics yield and selectivity, a good linear relationship between the light aromatics selectivity contributed by non-indene monocyclic aromatic hydrocarbons and the mass fraction of that was obtained, and it was calculated that the non-indene monocyclic aromatic hydrocarbons in hydrotreated LCO contributed to the light aromatics selectivity about twice as much as that of cycloalkanes for the same mass fraction in an effective mass fraction interval of the key components (30%-70%).

STUDY ON THE ENERGY EFFICIENCY OF PHOTOCATALYTIC DEGRADATION OF ALKANES BY COUPLING ADSORPTION-DESORPTION OF TiO₂-Bi₂WO₆/Zn(CH₃COO)₂-ACF COMPOSITE

2024, 55(5):  104-112. 

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TiO₂-Bi₂WO₆/Zn(CH₃COO)₂-ACF(TBZA) composite was prepared by hydrothermal and impregnation-sol-gel method,its morphology and structure of the composite were characterized by SEM, TEM, XRD, BET, UV-vis and I-T photocurrent response, and the degradation of propane in the adsorption-desorption coupling photocatalytic reactor was investigated. The results showed that the prepared materials had good photoelectron-hole separation rate. In the three-stage series adsorption-desorption coupled photocatalytic reactor, the propane mass concentration was 1000 mg/m³, the flow rate was 1.2 m³/h, the humidity was 33%, and the temperature was 34 ℃. The photocatalytic efficiency of TBZA composite was 85.8%, which was 48.9 percentage points higher than that of a single reactor, and the overall propane conversion decreased by less than 2% when the desorption temperature was 65 ℃ under ultraviolet irradiation, indicating that TBZA material had good performance as catalyst for recycling.

OPTIMIZATION RESEARCH ON LOW TEMPERATURE HEAT RECOVERY SYSTEM OF AIR COOLERS IN REFINERY

2024, 55(5):  113-122. 

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In response to the issue of low-temperature heat recovery and utilization of air coolers in some refinery units, the factors such as the grade of low-temperature heat source, load, process medium characteristics and operating conditions of the air coolers in each unit were analyzed comprehensively. According to seasonal variation, considering the periodicity fluctuation of the heat trap, the heat trap was set up to recover the heat step by step, and two sets of low-temperature heat recovery and utilization systems were set up to realize reasonable utilization of low-temperature heat in the air cooler. Two sets of low-temperature heat recovery and utilization systems can recover 299.3 MW heat, and the recovered low-temperature heat can be used for power generation, refrigeration, process unit heating, pipeline equipment tracing, building heating, and other aspects. All low-temperature heat can be fully utilized in winter, and surplus in summer.

STUDY ON MICROBIAL DEGRADATION OF TAIL POLLUTANTS FROM SOIL VAPOUR EXTRACTION (SVE ) IN GAS STATION

2024, 55(5):  123-134. 

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According to the composition and content of soil vapour extraction (SVE) tail pollutants in gas station soil, firstly, different concentrations of petroleum hydrocarbons were used to domesticate, enrich and screen petroleum hydrocarbon degrading microorganisms in activated sludge, and a total of 7 high-quality petroleum hydrocarbon degrading bacteria were isolated. Secondly, biodegradation experiment was carried out using the mixed degrading bacteria. After 180 days of biodegradation of artificially prepared simulated petroleum hydrocarbon contaminated soil (initial concentration 1 400 μg/g), the total biodegradation rate of petroleum hydrocarbons was more than 86%. Finally, the mixed degradation bacteria were used to degrade the real contaminated soil (initial concentration 1 532.3 μg/g) in the target gas station. The results showed that the mass fraction of total petroleum hydrocarbons in the truly contaminated soil was reduced to 342.6 μg/g (230 d) by the mixed microbial, which was lower than the risk-based assessment standard of Kansas in the United States (total petroleum hydrocarbon content in non-residential land was less than 450 μg/g), and the total biodegradation rate could reach 77.6%.

SIMULATION AND OPTIMIZATION OF EXTRACTIVE DIVIDING WALL COLUMN FOR CYCLOHEXANE/CYCLOHEXENE SEPARATION

2024, 55(5):  135-140. 

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In view of the separation of cyclohexane and cyclohexene in the product of partial hydrogenation of benzene to cyclohexene, an extractive dividing wall column(EDWC) process based on conventional extractive distillation process was proposed. The separation of cyclohexane and cyclohexenewas carried out by conventional extractive distillation and EDWCwith dimethyl sulfoxide as extractant.The equivalent and strict models of conventional extractive distillation and EDWC three-columnprocess were established by using Aspen Plus software, and the univariate analysis was carried out to obtain initial values for simulation. Based on multi-objective evolutionary algorithm (NSGA-Ⅱ),the multi-objective optimization of EDWC process was carried out, Pareto optimal solutions were obtained, and a set of solutions with the minimum annual total cost (TAC) and CO₂ emission were selected and compared with the conventional extraction distillation process. The simulation calculation results showed that compared with the conventional extraction distillation process, EDWC process could save TAC by 9.46% and reduce carbon emission by 17.25%. The results also revealed that the EDWC process was an effective energy-saving and carbon reduction method for separating cyclohexane and cyclohexene.

INTELLIGENT PERCEPTION TECHNOLOGY FOR CRUDE OIL SWITCHING IN ATMOSPHERIC AND VACUUM DISTILLATION UNITS AND ITS APPLICATION

2024, 55(5):  141-147. 

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In response to the problems such as the increase of operating load, the aggravation of product quality fluctuations and high energy consumption caused by the variety of crude oil, based on the principle of distillation, material balance, energy balance and big data, the on-line twinning model of distillation columns and the real-time perception technology of crude oil feed property were developed. The characteristic of this technology was to calculate the properties of crude oil according to the data of temperature, pressure and flow of crude oil distillation column, without the need for the installation of the real-time raw material analysis,nor the input of crude oil database and tank analysis data. Using scientific verification methods and processes, the veracity of the raw material property prediction model and twin process model was verified by using the production data of atmospheric and vacuum distillation units.An intelligent optimization control system for atmospheric column was developed,and the reliability of the system was verified by production data. By optimizing the system, the impact of crude oil switching on product properties was reduced, the naphtha yield was increased by 0.9% at the top of the atmospheric column, the yield of crude oil was increased by 0.8% atthe second line, and the energy consumption was reduced by 1.43%.

CRUDE OIL SCHEDULING OPTIMIZATION FOR COASTAL REFINERIES BASED ON EVOLUTIONARY MULTI-OBJECTIVE OPTIMIZATION

2024, 55(5):  148-156. 

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The optimization of crude oil scheduling for coastal refineries was studied,and a mixed-integer nonlinear programming model based on discrete time representation was developed. An efficient evolutionary multi-objective optimization algorithm,non-dominated sorting genetic algorithm,was used to solve the model. Aiming at the high-dimensional decision variables in crude oil scheduling optimization problem, the periodic rolling optimization strategy was used to reduce the dimension effectively, and Deb criterion was used to deal with the problem effectively.The results showed that the optimized scheduling plans were all feasible, the minimum number of formula switching was stable at 12-15, and the minimum total berthing time of oil tanker was stable at 123-132 h,which showed that the model and the optimized algorithm could effectively deal with the crude oil scheduling problem of coastal refineries.It can provide an optimal method for crude oil scheduling optimization in refineries which depends on artificial experience.

STUDY ON CORRELATION OF LOW TEMPERATURE APPARENT VISCOSITY OF No.8 HYDRAULIC TRANSMISSION OIL

2024, 55(5):  157-164. 

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In order to meet the needs of the lean production of No.8 hydraulic transmission oil and achieve the prediction and control of the low temperature apparent viscosity of No.8 hydraulic transmission oil in the blending control room, the correlation between the physical properties and the low-temperature apparent viscosity of No.8 hydraulic transmission oil prepared from different raw materials was studied. In order to grasp the change rule of apparent viscosity at low temperature and establish a prediction model of apparent viscosity at low temperature,the correlation between density, viscosity index, kinematic viscosity and low-temperature apparent viscosity was further studied by using the response surface methodology and Design-expert 12.0 software. The results showed that the kinematic viscosity (A), viscosity index (B) and 20 ℃ density (C) of No.8 hydraulic transmission oil hada high correlation with low-temperature apparent viscosity. After fitting, the regression equation of apparent viscosity at low temperaturewas (Y)obtained: Y=2 032.74+123.28 A-1 142.98 B + 574.01 C+680.72 AB-1 294.84 AC-1 091.62 BC,which was verified by the application of No.8 hydraulic transmission oil produced by 8 batches of different raw materials, the predicted value of apparent viscosity at low temperature was basically consistent with the measured value, and the reliability of the regression equation model was high.

RESEARCH ON DIFFERENTIAL SCANNING CALORIMETRY METHOD FOR THE DETERMINATION OF MELTING POINT OF PARAFFIN WAX

2024, 55(5):  165-171. 

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The melting point of paraffin wax was determined by means of differential scanning calorimetry (DSC) method, simulating the measuring process of melting point of paraffin wax(cooling curve method). The effects of starting and stopping temperatures, nitrogen purge gas flow rate, temperature rising and falling rate, sample mass, constant temperature time, sample preparation method, and temperature rising and falling times on the measurement results were studied,the suitable conditions for determining the melting point of paraffin wax by DSC method were determined, and the bias between DSC method and standard method (GB/T 2539-2008) was investigated. The results showed that the heating rate and cooling rate was 10 ℃/min and 5 ℃/min respectively when the melting point of paraffin wax was determined by DSC method, and the melting time should not exceed 1 h when the melting point was 20-30 ℃ above the predicted melting point. By testing 14 kinds of paraffin wax samples with 6 kinds of DSC instruments, the deviation between DSC and standard method was calculated to be -1.14 ℃. DSC method is a simple, rapid and repeatable method for determining the melting point of paraffin wax,and can be used as a control analysis method to quickly and accurately determine the melting point of paraffin wax.