Table of Content

12 December 2020, Volume 51 Issue 12

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INDUSTRIAL PRACTICE OF LTA TECHNOLOGY FOR CONVERTING LCO TO LIGHT AROMATICS

2020, 51(12):  1-5. 

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The industrial trial of LTA technology for converting LCO to light aromatics was carried out in a LCO hydrotreating unit with capacity of 705 kt/a and a catalytic cracking unit with capacity of 700 kt/a in SINOPEC Yangzi Petrochemical Company, Ltd. The results showed that using the hydrotreated LCO with density of 921.0 kg/m³, hydrogen content of 10.92% and polycyclic aromatics content of 18.7% as FCC feed, the once-through conversion was 70.90%, the yields of gasoline, C₆-C₈ aromatics and C₆-C₁₀ monocyclic aromatics were up to 64.53%, 23.91% and 35.53%, respectively in full recycle operation. In addition, the industrial results of LTA technology also proved that the hydrotreated LCO feed can meet the heat-balance operation of reaction and regeneration system, and meanwhile the operation of the fractionator and absorbing-stabilizing system can be stable.

REMOVAL OF HEAVY COMPONENTS FROM SULFOLANE IN BTX EXTRACT-DISTILLATION PROCESS

Gao Siliang Tang Wencheng Zhao Ming Tian Longsheng

2020, 51(12):  6-11. 

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The accumulation of heavy components in lean solvent occurs in the extraction-distillation process of pyrolysis gasoline after hydrogenation. The purification effect of sulfolane solvent were investigated by four methods: back-extraction of reffinate, water washing of lean solvent, water washing of rich solvent, and combination of back-extraction of raffinate and water washing. The results showed that among all the heavy components，the linear alkylbenzenes were the easiest to remove，while the separation of polycyclic aromatics were the most difficult；temperature had a certain influence on the removal of the heavy components，and the effect was different in different methods. The purification results of back-extraction and water washing coupling methods for raffinate were the best. The mass fraction of sulfolane in the lean solvent can increase from 94.25% to 99.86% under the following conditions：the ratio of raffinate to lean solvent of 1.0，the washing water to the solvent ratio of 1.0，the temperature of 40℃. The purified solvent meets the purity requirement of recycled lean solvent for industrial production.

COMMERCIAL APPLICATION OF HYDROCRACKING TECHNOLOGY FOR IMPROVING HEAVY NAPTHA AND JET FUEL YIELD

2020, 51(12):  12-16. 

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In order to satisfy the increasing market demand of jet fuel and chemical materials, the hydrocracking technology for improving heavy naphtha and jet fuel yield developped by SINOPEC Research Institute of Petroleum Processing was applied in 2.7 Mt/a hydrocracking unit of PetroChina Sichuan Petrochemical Company in2018. The caliberation results after 14 months operation illustrated that with unconverted oil yield of 18.86%, heavy naphtha yield was 29.47%; the jet fuel yield reached 36.24%, 11.48 percentage points higher than the last operation cycle and met the requirements of No.3 jet fuel. The unconverted oil with BMCI value of 7.8 was the high quality feedstock for steam cracking. The goal of increasing heavy naphtha and jet fuel yields was achieved while reducing diesel oil and improving the quality of chemical raw materials.

IN-SITU REGENERATION OF HIGH COKE DEPOSIT CONTINUOUS REFORMING CATALYST

2020, 51(12):  17-21. 

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Because the carbon content of high coke deposit continuous reforming catalyst is far beyond the level allowed by the normal operation of the regeneration system, the normal continuous regeneration in the reactor will lead to the destruction of catalyst support crystal phase and the damage of reactor internals.Taking the abnormal increase of carbon content caused by abnormal shutdown of a CCR unit as an example, under the condition of no feed into the reforming reaction system, through strictly controlling the parameters such as inlet temperature, inlet oxygen content and catalyst circulation rate in the regenerator, the coke burning in fixed bed and continuous coke burning in moving bed were adopted in the regenerator to reduce the catalyst carbon content in the unit. Then, the normal regeneration of catalyst was realized and the activity of catalyst was fully recovered. It became the first successful case of in-situ regeneration of high coke deposit continuous reforming catalyst in China.

PROCESS SELECTION AND ANALYSIS OF CHANGING VENTING GAS INTO WET GAS COMPRESSOR IN DELAYED COKING UNIT

2020, 51(12):  22-27. 

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The main media in the coke drum venting process in delayed coking unit are venting gas and steam, which contains coke powder and sulfides. In order to avoid the blockage and pipeline corrosion of dry gas low pressure separator caused by coke powder and sulfides, the refinery decided to enter the venting gas of coking unit into coking wet gas compressor. The industrial application results showed that excessive coke powder blocked the tube bundle of air cooler at the top of fractionator, and also affected the heat transfer of water cooler, which needs tracking detection; no obvious impact on the operation of coking wet gas compressor was found, the vibration value of the compressor and the flow rate of main seal gas only slightly increased; the venting and coke cooling rate were not affected. When the pressure of the vent cooling tower was close to that of the fractionator tower, the venting gas should be changed into the low-pressure flare system in time; the desorbed gas could be completely consumed through the converter; At the same time, the cleaning frequency of dry gas compressor cooler in the low-pressure dry gas separation unit was from once a month to more than 4 months, which realizes the long-term operation of dry gas compressor.

PREPARATION OF ENVIRONMENTAL-FRIEDLY RUBBER PROCESSING OIL FROM RAFFINATE OF COAL-BASED HYDROCRACKING TAIL OIL

2020, 51(12):  28-32. 

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The coal-based environmental-friendly rubber oil was prepared using the raffinate oil of coal tar hydrocracking tail oil．The combined process of hydrodewaxing and solvent extraction was adopted to reduce the pour point and remove the polycyclic aromatic hydrocarbons in the raffinate．The results showed that the pour point of the raffinate was decreased from 26 ℃ to －6 ℃ at 5.0 MPa，350 ℃，mass space velocity of 1.0 h^-1 and volume ratio of hydrogen to oil of 800∶1．Two-stage countercurrent extraction test was carried out for the fraction with boiling point higher than 300℃ in the oil after hydrodewaxing by two-stage counter-current extraction with furfural as the solvent at extraction temperature of 60 ℃ and the mass ratio of the agent to oil of 2∶1．The eco-friendly rubber oil with a polycyclic aromatic hydrocarbons content of 1.88% and a value of aromaticity (CA) of 12.0% was prepared．The main properties meet the requirement of environmental-friendly rubber oil A0709 in the national standard GB/T 33322—2016．

STUDY ON Pt-SO₄^2-/ZrO₂-Al₂O₃ SOLID SUPERACID CATALYST

2020, 51(12):  33-40. 

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ZrO₂-Al₂O₃ was prepared by co-precipitation method, SO₄^2-/ZrO₂-Al₂O₃ was prepared by impregnating ZrO₂-Al₂O₃ with sulfuric acid solution, and Pt-SO₄^2-/ZrO₂-Al₂O₃ solid superacid catalyst was prepared by impregnating platinum chloride solution by equal volume method. BET, XRF, XRD, NH₃-TPD, Py-IR techniques were used to characterize the pore structure, crystal phase structure, and acid properties of different Pt- SO₄^2-/ZrO₂-Al₂O₃ catalysts. The n-hexane was used as the probe material to evaluate the conversion and isomerization activity of Pt-SO₄^2-/ZrO₂-Al₂O₃ catalysts. The results showed that when the content of Al₂O₃ was 5%, the roasting temperature of SO₄^2-/ZrO₂-Al₂O₃ was 650 ℃, and the sulfuric acid added was 15%, the tetragonal phase zirconia content of Pt- SO₄^2-/ZrO₂-Al₂O₃ catalyst was the highest, the total acid content and the amount of B acid were the most, and both the conversion and isomerization rate of n-hexane were the highest. At 2.0 MPa, 240 ℃, volumetric space velocity of 1.0 h^-1, and hydrogen-to-oil volume ratio of 700, the conversion of n-hexane on Pt-SO₄^2-/ZrO₂-Al₂O₃ catalyst was 88.72%, the isomerization rate was 80.07%.

DEVELOPMENT AND INDUSTRIAL APPLICATION OF HEAVY OIL CRACKING CATALYST WITH LOW COKING AND HIGH LPG YIELD

2020, 51(12):  41-44. 

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A heavy oil catalytic cracking catalyst M with low coke and high LPG selectivity was developed by using high activity ultrastable molecular sieve and new shape selective technology and applied in the RFCC unit of a petrochemical company. The application results showed that compared with the blank calibration, when the raw materials and operating conditions were roughly the same and the catalyst M accounted for 80% of the system reserves, the processing load of the device increased by 5%, the yield of liquefied gas and the total liquid yield increased by 1.72 and 0.18 percentage points, respectively, the gasoline yield and diesel yield decreased by 1.23 and 0.21 percentage points, respectively, the oil slurry and coke yield decreased by 0.14 and 0.16 percentage points, respectively, and the dry gas yield remained basically unchanged. The new developed catalyst M showed a strong bottom oil conversion ability and excellent coke selectivity and could convert a large number of gasoline molecules into LPG without decreasing the total liquid yield and can meet the LPG demand of the plant.

PREPARATION AND PERFORMANCE EVALUATION OF HYDROFINING CATALYST FOR LOW VISCOSITY PAO

2020, 51(12):  45-49. 

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Boron was added in the preparation process of alumina carrier for modification. The hydrofining catalyst for low viscosity PAO based on the modified carrier was prepared by equal volume impregnation. The modified carrier and catalysts were characterized by BET, XRD, H₂-TPR, and Hy-IR techniques. The characterization results showed that the boron modified hydrofining catalyst carrier reduced the interaction between the active metal components and the carrier. The acidity of the catalyst was greatly enhanced and B acid was produced at the same time. At atemperature of 240 ℃, a hydregen pressure of 4.5MPa,a space velocity of 0.2h^-1 and a volume ratio of hydrogen to oil of 300:1, the aromatics saturation performance of modified hydrofining catalyst applied to PAO4 hydrogenation was investigated and compared with that of unmodified catalyst, the results showed that both of the catalysts could effectively improve the color of the product, but the aromatic saturation performance of the modified catalyst was much better than that of the unmodified catalyst. The stability evaluation results of the modified hydrofining catalyst showed that the catalyst had good activity and stability, which can meet the requirements of industrial application.

STUDY ON PERFORMANCE OF CLINOPTILOLITE-BASED CATALYST FOR OIL SAND BITUMEN UPGRADING

2020, 51(12):  50-54. 

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Hydrothermal catalytic cracking catalyst with high efficiency of viscosity reduction, sulfur and nitrogen resistance is the key to the utilization technology of oil sand bitumen resource. H-type clinoptilolite carrier and microporous Ni-based catalyst were prepared using natural clinoptilolite. Its performance in hydrothermal cracking of the model compound and in visbreaking and upgrading of SAGD oil sand bitumen in McCann, Canada were investigated. The results showed that the Ni-based clinoptilolite catalyst exhibited good catalytic cracking performance and hydrothermal stability in the process of hydrothermal cracking with n-hexadecane as the model compound. The catalyst could significantly reduce the bitumen viscosity, increase the yield of middle distillate oil, and reduce the sulfur and nitrogen content to a certain extent. It could be used for viscosity reduction and upgrading of oil sand bitumen under medium and low temperature and non-hydrogen conditions.

PREDICTION MODEL FOR HYDROGEN SOLUBILITY IN DIESEL BASED ON PR EQUATION OF STATE

2020, 51(12):  55-63. 

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A hydrogen solubility prediction model based on the Peng-Robinson equation of state (PR EOS) was established. The experimental data of hydrogen solubility of typical diesel compounds were collected from literature. The PR EOS binary interaction parameters between hydrogen and typical model compounds were regressed from experimental data. An empirical correlation was built between the binary interaction parameters and the key properties of molecules. Based on the developed model，the hydrogen solubilities in typical model compounds and diesel oil products were predicted，and the average relative errors of hydrogen solubility in straight-chain alkanes，cycloalkanes and aromatic hydrocarbons were 4.45%，11.84%，8.50%，respectively. The hydrogen solubilities in several diesel samples at different temperatures and pressures were predicted with a good agreement between predicted and measured values were observed，showing the validity of the developed model.

INFLUENCES OF COMPOSITIONS OF AROMATIC-RICH OILS ON FORMATION OF MESOPHASE PITCH

2020, 51(12):  64-68. 

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Mesophase pitch is recognized as excellent precursor for making new carbon material. The quality of mesophase is closely related to the structural properties of its raw material. Distillate oils with different structural composition obtained from aromatic-rich oil were used for preparing mesophase pitch by thermal polycondensation. The molecular weight and molecular structure of the three distillate oils were characterized. The polarized optical microscopy, FT-IR, TG and XRD were used to analyze the optical texture, microcrystal and molecular structure of mesophase pitches for investigating the effects of molecular weight and structure of raw material on the formation and development of mesophase. The results showed that the structural composition of the raw material played an important role on the properties of mesophase pitch. It was found that the raw material with narrow molecular-weight distribution and more naphthenic structures was conducive to the generation of mesophase pitch with high content of anisotropic structure, low softening point and ordered crystal structure.

PREDICTION OF GASOLINE RESEARCH OCTANE NUMBER BASED ON RANDOM FOREST REGRESSION

2020, 51(12):  69-75. 

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Aiming at the detection difficulty of gasoline Research Octane Number (RON) in fuel sales enterprises, a RON prediction method based on random forest regression algorithm was proposed. Based on the fuel quality database, with gasoline olefin content, aromatic content, oxygen content, distillation range (T10, T50, T90 and FBP) and density as independent variables and RON value as the dependent variable, the random forest regression prediction models of NO.92 gasoline, NO.95 gasoline and ( NO.92+ NO.95) gasoline were established. The results showed that the prediction accuracy of models for the NO.92 and the NO.95 gasoline was better, and the coefficient of determination (R2) of the two models both reaches 0.95. After the fuel quality upgraded, the prediction models maintained high accuracy, reliability, and adaptability. Compared with the mid-infrared spectral detection method, the absolute error of more than 84% prediction results of the random forest regression model was less than 0.7, and its accuracy was significantly better than that of the mid-infrared spectral detection method. This prediction model can be helpful for the quality monitoring of gasoline RON of fuel sales enterprises.

EFFECT OF MODIFIED GRAPHENE ON TRIBOLOGICAL PROPERTIES OF HYDRAULIC OIL

2020, 51(12):  76-81. 

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Three kinds of modification methods were used to modify the active functional groups of five graphenes with different thicknesses and different oxidation degrees to improve their dispersion stability in hydraulic oil. The dispersion of modified graphenes was investigated through long standing test and centrifugal test. The effect of modified graphenes on the friction and wear performance and anti-oxidation performance of hydraulic oil was investigated by four-ball machine friction test and oxidation stability test. The results showed that after modified by KH570, MMA, oleylamine and oleic acid, the few or multi-layer graphenes with low oxidation degree, had poor dispersion stability when added into hydraulic oil. And the high-oxidation graphenes modified by oleamine or oleic acid, when the added amount was 0.01%, the hydraulic oil obtained good oil solubility with stable dispersion for more than one year. At the same time, anti-wear, anti-friction and extreme pressure performance of hydraulic oil was significantly improved.

INVESTIGATION ON SERVICE PERFORMANCE OF LONG-LIFE ANTIWEAR MOTOR BEARING GREASE

2020, 51(12):  82-84. 

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The performance of a long life anti-wear motor bearing grease was investigated. Comparative test analysis of infrared spectrum, high pressure differential thermal scanning and SRV was carried out on grease after 518 hours. The analysis results show that the overall performance of the developed long-life anti-wear bearing grease has little change from that of the unused long-life anti-wear motor bearing grease after being used for 518 h, and the grease still has excellent oxidation resistance and anti-wear performance, which is superior to Russian СЭДА grease.

QUANTITATIVE STUDY OF STORAGE TANKS VOCs EMISSION CHARACTERISTICS BASED ON TANKS 4.0.9d MODEL

2020, 51(12):  85-91. 

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Based on the Tanks 4.0.9d model published by US EPA, the paper quantitatively studied the emission characteristics and influence factors on VOCs emission from the storage tank. The difference between the measured data and the model calculation results was analyzed. The results showed that the emissions of storage tanks were affected by tank structural characteristics, environmental factors, and operating conditions. The emission of the internal floating roof tank was the smallest, and the emission of the fixed roof tank was 110.5 times that of the former tank. The reduction of the tank emission could be realized by measures of painting the outer wall of the tank with white primer, regularly spraying water, installing heat insulation baffle, using anti-rust and anti-corrosion coating on the inner wall of the tank, and using LDAR (leak detection and repair) technology to regularly and quantitatively check the leakage of storage tank and repair them in time. It was found that the measured data of internal floating roof gasoline tank was 3.5 times that calculated by the model, showing that the emission from field monitoring was higher than that of calculation by the model. There are limitations in both actual measurement and model calculation. It is suggested that developing new optimized calculation softwares are of great necessity based on the domestic situation.

ORGANIC RANKINE CYCLE POWER GENERATION USING LOW TEMPERATURE WASTE HEAT IN REFINERY AND ITS BENEFIT ANALYSIS

2020, 51(12):  92-95. 

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A petrochemical company adopted organic Rankine cycle to recover low temperature waste heat from condensed water，steam and exhaust steam in the power generation process. The present situation and the process of power generation using every kind of low temperature waste heat in the company were described. The economic and environmental benefits of the power generation project were analyzed. The results indicated that the annual net income of power generation was 8.698 million Yuan; the annual average income of recycling soft water was 8.19 million Yuan, and the entire investment can be recovered in one year and a half. The annual energy saving reached about 169 354 GJ, the annual reduction amount of CO₂ was about 12.9 kt. The implementation of this power generation project is of great significance for improving the energy efficiency of the whole plant, creating energy-saving enterprise and promoting the company's energy saving and consumption reduction plan.

RAPID DETERMINATION OF TRACE CONTAMINANTS IN LIGHT PETROLEUM PRODUCTS BY ED-XRF

2020, 51(12):  96-101. 

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A rapid accurate method for determination of trace pollutants in light petroleum products, including silicon, phosphorus, sulfur and chlorine-containing compounds, was established by using ED-XRF. The target material of X-ray source, matrix effect and the interfering factors for the measurement process were investigated and optimized. The validation was carried out by the standard addition. The results showed that the established method had a good linear relationship with silicon, phosphorus, sulfur, chlorine content with R² more than 0.999. The detection limits of silicon, phosphorus, sulfur and chlorine were 2.0, 0.8, 0.5, 0.2 μg/g, respectively. The adding standard recoveries were between 95.1%-105.0%，the relative standard deviation was less than 6.0%. It could be used for rapid determination and screening of harmful impurities in light petroleum products.

COMPARATIVE STUDY ON CLOSED CUP FLASH POINT TEST METHODS

2020, 51(12):  102-106. 

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In this study, the commonly used test methods for closed cup flash point measurement,Pensky-Martens closed cup method, Abel closed cup method and Tag closed cup method, were analyzed comparatively. The closed cup flash points of two certified reference material samples, four organic compound samples and seven jet fuel samples were tested by these three methods. It was found that there were some differences of the three methods in application scope, instrument structure, temperature rise speed, ignition operation requirements. As a result, the closed cup flash points of the same sample determined by these three methods were slightly different. The maximum difference among the test results of the same sample by the three methods was positively correlated with its flash point. In general, the flash point determined by Pensky-Martens closed cup method was a little higher than that of Abel closed cup method. For No.3 jet fuel samples, the difference of flash points was 0-1.0 ℃, and in comparison, Abel closed cup method was the most suitable for the determination of closed cup flash point of No.3 jet fuel. For pure organic compound samples, there is a good linear relationship between the results by Pensky-Martens closed cup method and Abel closed cup method.

APPLICATION OF RARE EARTH COMPOUND IN GREASE

2020, 51(12):  107-110. 

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Rare earth elements have excellent tribological properties. In order to better understand the research trends of rare earth compounds in the field of grease, the basic information of rare earth elements and the study history of tribological properties of rare earth compounds are briefly introduced. Starting from the research of rare earth compounds in greases, the research situation of inorganic rare earth compounds and surface modified rare earth compounds as grease additives is introduced. Rare earth elements have excellent tribological properties, which can improve the friction reduction and wear resistance of lubricating grease to different degrees and are superior to ZDDP under certain conditions. The basic situation and problems in the application of inorganic rare earth compounds and polyurea-organic acid lanthanum compounds as greases thickeners are also briefly introduced. Finally, the friction reduction and anti-wear mechanism of rare earth compounds are briefly discussed, and the bright prospects for the application of rare earth compounds in the field of grease are also prospected.