Table of Content

12 February 2022, Volume 53 Issue 2

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INDUSTRY CHAIN ANALYSIS OF NEEDLE COKE AND ITS MARKET DEVELOPMENT MEASURES

Huang Yousheng

2022, 53(2):  1-5. 

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The production and consumption of needle coke in China were analyzed, and its application prospect in graphite electrode and anode material industry was forecasted. The challenges faced by the development of oil-based needle coke were studied, including the supply of raw materials, insufficient quality, long application evaluation period and excess capacity, etc. Measures such as increasing product subdivision research and application performance correlation research were put forward to explore the high-end market.

APPLICATION OF QUANTUM CHEMICAL CALCULATION AND MOLECULAR DYNAMICS SIMULATION IN METAL-WORKING FLUIDS INVESTIGATIONS

2022, 53(2):  6-14. 

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Applications of quantum chemical calculation and molecular dynamics simulation in the personalized design, customization and evaluation of metal-working fluids were overviewed. Quantum chemical calculation can accurately obtain the chemical reactivity of various molecules in the metal-working fluids, the adsorption behavior on the metal surface and other microscopic properties, so as to realize the efficient screening and design of additives such as friction improver and antirust agent. The advantage of molecular dynamics simulation is the ability to obtain the physical and chemical properties of metal-working fluids, such as viscosity and thermal conductivity, to simulate or reproduce the actual metal-working process, including the friction and lubrication procedure, especially the macroscopic properties of complex solid-liquid system containing nano-additives. Two methods will further provide the theoretical guidance for the optimization of functional and individualized formula of metal working fluid and the evaluation of high efficient performance, realizing from molecular scale to macro scale, and from microscopic properties to physicochemical behaviors, “bottom-up” design and development.

RESEARCH AND INDUSTRIAL APPLICATION OF CATALYTIC CRACKING TECHNOLOGY FOR PRODUCING ULTRA-LOW OLEFIN GASOLINE

2022, 53(2):  15-22. 

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With the increasingly stringent environmental regulations, reducing the olefin content of FCC gasoline has practical significance. Based on the mechanism of the hydride ion transfer reaction on the bimolecular reaction, a new concept of selective hydrogen transfer reaction is proposed to regulate and control gasoline olefins. It is found that the components rich in naphthenic aromatics and polycyclic alkanes can be used as hydride ion release agents to control gasoline olefins and inhibit the formation of coke. Through technological innovations such as the regulation of reaction modes, and the introduction of hydride ion release agents, the catalytic cracking technology for producing ultra-low olefin gasoline (ULO) has been successfully developed. The industrial application results show that ULO technology can be used to produce stable gasoline with a volume fraction of olefin less than 10%, maintaining gasoline octane number and coke selectivity, to realize the high-value conversion of LCO.

OPTIMIZATION MEASURES AND EFFECT OF ENERGY EFFICIENCY IMPROVEMENT OF XYLENE UNIT

2022, 53(2):  23-29. 

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Para-xylene is the main target product in xylene unit of aromatics unit, but its energy consumption is high. Taking the common problems of restricting energy efficiency of xylene unit as the breakthrough point，the heat exchange process of xylene unit was optimized to reduce the fuel gas consumption of the reboiler of xylene column. A new type of wound tube heat exchanger was developed to improve the design accuracy of heat exchanger. At the same time，the low temperature heat recovery network system of xylene unit was systematically designed，which significantly reduced the energy consumption of the unit. The industrial application results showed that the total amount of fuel gas consumption was reduced by 0.87 t/h, the low-temperature heat was recovered by 29.56 MW, and the comprehensive energy consumption was reduced by 3 118.6 MJ/t，greatly improving the energy efficiency of the xylene unit, and the energy-saving modification of xylene plant is of guiding significance.

IMPROVEMENT MEASURES FOR NAPHTHENIC BASE OIL YIELD IN HYDROGENATION UNIT

2022, 53(2):  30-34. 

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The naphthenic base oil (U30 transformer oil, N4010 rubber plasticizer) was produced by a high-pressure hydrogenation unit in CNOOC Oil & Gas (Taizhou) Petrochemical Co., Ltd. Aiming at the problem that the calibration results of naphthenic base oil produced by the unit was lower than the designed value, the influence factors was analyzed. In order to improve the yield of naphthenic base oil, some measures was taken, such as increasing the lubricating oil composition of the feedstock, increasing the space velocity, reducing the depth of the dewaxing reaction, and controlling product indicators on their indicator boundaries. The results showed that the average yield of naphthenic base oil was increased from 83.67% to 86.50%, and the highest yield could reach 89%.

COKING REASON OF BOTTOM REBOILER OF DEPROPANIZER IN DCC UNIT AND COUNTERMEASURES

2022, 53(2):  35-39. 

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The coking of butadiene in the bottom reboiler of depropanizer in a deep catalytic cracking (DCC-plus) unit in a company seriously affects the long-term operation of the unit. The comprehensive analysis shows that the high content of butadiene in LPG, the high reboiler heat source temperature, and the high content impurities such as oxygen and alkaline matter cause coking and fouling. By means of optimizing the separation process, transforming reboiler heat source, reducing impurities such as oxygen, strengthening system equipment passivation, injecting the inhibitor, the coking and scaling rates can be greatly reduced, to ensure the long period operation of the unit.

EFFECT OF NICKEL ON CONTACT CRACKING CATALYST AND CONTACT CRACKING OF RESIDUE

2022, 53(2):  40-45. 

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Four kinds of contact agents with high nickel content were prepared by saturated impregnation method. The effects of nickel on the physical properties of contact agent were studied by BET, XRD, H₂-TPR, EPMA and other means. The effects of nickel on the contact cracking of residue were investigated in a small fixed fluidized bed experimental equipment. The results show that nickel has little effect on the pore structure of the contact agent, even if the nickel content on the contact agent reaches 5.17 %. The specific surface area and pore volume of the contact agent have little change. Nickel on the contact agent promoted the formation of dry gas and coke in the process of heavy oil contact cracking, especially the increase of coke yield, which led to the increase of hydrogen generation factor and promoting the dehydrogenation performance of the contact agent.

DEVELOPMENT AND APPLICATION OF RF-4 CATALYST FOR MOVING-BED LIGHT HYDROCARBON AROMATIZATION

2022, 53(2):  46-52. 

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In order to meet the requirement of moving-bed light hydrocarbon aromatization for the continuous flow performance of catalyst, a spherical zeolite catalyst RF-4 with independent intellectual property was developed by SINOPEC Research Institute of Petroleum Processing. The new catalyst exhibited excellent catalytic performance and continuous flow properties, such as high aromatization activity, high crushing strength, high spherical degree and good regeneration performance, which broke through the key technology in the development of moving-bed light hydrocarbon aromatization. The results of industrial application showed that catalyst RF-4 had excellent activity and stability in the moving-bed aromatization unit with light hydrocarbons as raw materials, and it had broad application prospects.

PREPARATION OF Ni-MoO₃/SG AND ITS CATALYTIC PERFORMANCE OF OXIDATIVE DESULFURIZATION

2022, 53(2):  53-62. 

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n%-Ni-MoO₃/SG（n＝2.0，5.0，7.0） catalyst was synthesized by sol-gel method using Ni-MoO₃ as active component and silica gel (SG) as carrier. The structure of the catalyst was characterized by Fourier transform infrared spectrum(FT-IR），X-ray diffraction(XRD)，scanning electron microscope(SEM），N₂ adsorption-desorption，and X-ray photoelectron spectroscopy(XPS). The removal of dibenzothiophene(DBT） from simulated oil was studied with Ni-MoO3/SG as catalyst，H2O2 as oxidant and acetonitrile as extractant. The effects of active component loading，reaction temperature，amount of catalyst，oxygen-sulfur molar ratio （O/S），addition amount of extractant，and types of sulfides on desulfurization were investigated. The experimental results showed that the sulfur removal rates of the simulated oil of DBT，4，6-dimethyldibenzothiophene （4，6-DMDBT） and benzothiophene(BT) were 99.4%，93.6%，and 99.1% ,respectively, under the optimal reaction conditions, and the sulfur removal rate of the simulated oil of DBT could still reach 93.7% after 5 times recycling.

EFFECT OF ZINC SILICATE ON DESULFURIZATION ACTIVITY OF S Zorb ADSORBENT

2022, 53(2):  63-68. 

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Effect of zine silicate on desulfurization activity of S Zorb adsorbent was studied in a fixed bed reactor. The results showed that the sorbents had higher desulfurization activity, and the sulfur breakthrough capacity were more than 12% when there was no zinc silicate in the S Zorb adsorbent. The sorbents had little influence on sorbents desulfurization activity and selectivity when the content of zinc silicate was low. The great increase of zinc silicate content had a significant effect on the sulfur carrying capacity of the adsorbent. When the mass fraction of zinc silicate in the adsorbent was 39.4%, the sulfur breakthrough capacity of the adsorbent was decreased to 2.18%, and the desulfurization activity of the adsorbent was decreased greatly. When the mass fraction of zinc silicate in the adsorbent was low, the adsorbent could maintain high desulfurization rate and high desulfurization selectivity, which could avoid excessive olefin hydrogenation saturation and reduce the octane number loss of gasoline. In addition, the increase of zinc silicate in adsorbent could reduce the desulfurization selectivity of the S Zorb adsorbent and lead to more olefin saturation and RON loss while producing gasoline products with sulfur content below 10 μg/g. Therefore in the operation of S Zorb commercial units, the operating conditions should be controlled to reduce the formation of zinc silicate as much as possible.

SYNTHESIS OF X ZEOLITE WITH LOW SILICA TO ALUMINA RATIO

2022, 53(2):  69-76. 

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In order to synthesize pure low silicon X zeolite with high crystallinity, the effects of n(SiO₂)/n(Al₂O₃) , n(Na₂O+K₂O)/n(SiO₂),n(H₂O)/n(Na₂O+K₂O)  and n(K₂O)/n(Na₂O+K₂O)  as well as aging and crystallization temperature on the properties of the products were systematically investigated. The products were characterized by X-ray diffraction, dynamic adsorption of toluene, X-ray fluorescence spectrum, solid state nuclear magnetic resonance, and scanning electron microscopy. The results showed that with the increase of n(SiO₂)/n(Al₂O₃) , n(Na₂O+K₂O)/n(SiO₂) ,n(H₂O)/n(Na₂O+K₂O) ，n(K₂O)/n(Na₂O+K₂O) , aging temperature and crystallization temperature, the crystallinity and toluene adsorptive capacity of the synthesized low silicon X zeolite was increased firstly and then decreased. Under the optimum conditions covering a n(SiO₂)/n(Al₂O₃) of 2.05, a n(Na₂O+K₂O)/n(SiO₂) of 3.25, a n(H₂O)/n(Na₂O+K₂O) of 17, a n(K₂O)/n(Na₂O+K₂O) of 0.23, an aging temperature of 50－80 °C, and a crystallization temperature of 95 °C, the low silicon X zeolite with high crystallinity degree can be obtained. The low silicon X zeolite with a n(SiO₂)/n(Al₂O₃) of 2.0 without non-framework Al, shows sphere morphorology with a diameter of 0.5－1.5 μm.

REACTION BEHAVIOR OF ATMOSPHERIC GAS OIL DURING CATALYTIC CRACKING AND THERMAL CRACKING

2022, 53(2):  77-83. 

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The catalytic cracking and thermal cracking reactions of atmospheric gas oil（AGO）were investigated in a small fixed fluidized bed reactor at 520－680 °C using acid catalyst and quartz sand respectively. Compared with thermal cracking, the catalytic cracking of AGO had the advantages in increasing its conversion, decreasing the dry gas yield and increasing the LPG yield, which could reduce the ethylene yield by 1.67－3.78 percentage points, increase propylene yield by 5.23－9.12 percentage points and the butene yield by 3.32－7.94 percentage points respectively, so as to the BTX yield. The content of methane and ethylene in the dry gas of catalytic cracking and thermal cracking of AGO had the same change trend with reaction temperature, but the volume fraction of hydrogen in catalytic cracking dry gas was greater than ethane, while the volume fraction of hydrogen in thermal cracking dry gas was lower than ethane. When the reaction temperature was higher than 600 ℃, the mole ratio of C2H4/CH4 of catalytic cracking dry gas was less than the optimal distribution value of thermal cracking dry gas（0.82）. The changing trends of n-alkane, isoalkane, olefin and aromatic in the two kinds of cracking gasoline were similar, but the changing trend of naphthene was opposite. The naphthene in catalytic cracking gasoline decreased with the increase of reaction temperature, while the naphthene in thermal cracking gasoline increased with the increase of reaction temperature.

MOLECULAR SIMULATION OF n-HEXANE ADSORPTION ON HZSM-5 ZEOLITES WITH DIFFERENT Si/Al RATIO

2022, 53(2):  84-92. 

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The adsorption behavior of n-hexane on HZSM-5 zeolites with different Si/Al ratios has been simulated by Grand Cannonical Monte Carlo method. By simulating the adsorption of n-hexane molecules on HZSM-5 zeolites with different Si-Al ratios at 298 K and 423 K, some parameters such as the adsorption isotherm, adsorption energy density, adsorption potential energy, radial distribution function and other related parameters were obtained and analyzed, and the effect of Si/Al ratio on the adsorption behavior of n-hexane was also analyzed. The results show that the adsorption between n-hexane and HZSM-5 zeolite accords with the Langmuir-Freundlich adsorption model. When the Si/Al ratio is high, n-hexane molecules adsorbs preferentially on B acid sites of T3 and T9 in the inter channels of HZM-5 zeolites and the interaction between n-hexane molecules is more obvious than other B acid sites. With the decrease of Si/Al ratio, the saturated adsorption capacity of n-hexane was increased, the adsorption ratio of n-hexane molecules adsorbed in the straight channel was increased, and the interaction between hexane molecules was weaken.

STUDY ON THE INFLUENCING FACTORS OF EVAPORATION LOSS OF LUBE BASE OIL

Wang Luqiang

2022, 53(2):  93-98. 

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Using the representative hydrocracking tail oil as raw material，the effects of raw material composition and corresponding base oil composition, the range of the feedstock distillation range and the processing technology on the evaporation loss of the base oil were investigated by two evaporation loss analysis methods, NB/SH/T 0059 and SH/T 0695. It is found that the structural and composition of base oil were the key and the internal factors affecting the evaporation loss, and the content of alkanes in base oil could be increased by various technological means. The viscosity and distillation range of the base oil were the external factors affecting the evaporation loss，which could be reduced by optimizing the feedstock and operating the fractionating column. The effective measures to reduce the evaporation loss of base oil were put forward.

STUDY ON THE PROPERTIES OF HIGH TEMPERATURE ANTIOXIDANT ALKYLATED N-PHENYL-α-NAPHTHYLAMINE

2022, 53(2):  99-104. 

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A high temperature antioxidant,alkylated N-phenyl-α-naphthylamine,was successfully synthesized in laboratory. The structure and purity of the antioxidant were characterized by IR,MS and GC. The oxidation resistance of the antioxidant in base oil was investigated by means of pressure differential scanning calorimetry (PDSC) and oven oxidation method. The antioxidant performance in aviation engine oil and SM specification gasoline engine oil was also evaluated. The results show that alkylated N-phenyl-α-naphthylamine has higher thermal decomposition temperature and oxidation stability, compared with the conventional antioxidant, which can meet the requirement of antioxidants in high temperature environment.

DEVELOPMENT OF SN/GF-5 GASOLINE ENGINE OIL

2022, 53(2):  105-110. 

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The gasoline engine oil with independent intellectual property rights to meet SN/GF-5 specification was developed by using domestic additives and base oil. The combination of complex antioxidant, complex antifriction agent and anti-wear agent zinc dialkyldithiophosphate(ZDDP) for gasoline engine oil was selected by simulation test. The results show that the composite antioxidants with the mass ratio of long chain diphenylamine antioxidants and phenol ester antioxidants of 3:7 can greatly improve the antioxidant performance of the lubricating oil. The friction-reducing performance of the oil can be improved obviously by the combination of the amide friction modifier and the molybdenum carbamate, and the wear-resisting performance of the di-sec-alkyl ZDDP is the best among the three structures. The developed gasoline engine oil has passed the engine tests of program ⅢG, ⅢGA, ⅢGB, ⅣA, ⅤG, ⅥD, Ⅷ, and each performances has reached the SN/GF-5 specification.

OPERATION OPTIMIZATION AND ENERGY-SAVING MODIFICATION OF FRACTIONATOR IN DIESEL HYDROGENATION UNIT

2022, 53(2):  111-116. 

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With the help of Aspen Plus 10 and system model recommendator, the fractionation of No. 4 diesel hydrogenation unit in SINOPEC Maoming Companywas simulated, analyzed and optimized by Chao-Seader and Galyson-Streed thermodynamic models. The results show that the simulation results are in good agreement with the actual operation data of the unit. Through the analysis and optimization of feeding stage and feeding temperature of the cold and hot low pressure separator oil in the fractionator, and the matching adjustment of the heat exchanger flow, as well as the transformation of the cold and hot low pressure separator oil into the fractionator separately, the final heat exchange temperature of cold low pressure separator oil is raised to 210 ℃, the consumption of stripping steam in the fractionation process is reduced by 1.7 t/h, and energy-saving effect is remarkable.

STUDY ON THE HIGH-PERFORMANCE CHROMATOGRAPHIC METHOD FOR THE DETERMINATION OF POLYCYCLIC AROMATIC HYDROCARBONS IN DIESEL FUELS

2022, 53(2):  117-122. 

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At present,the standard method SH/T 0806-2008 “Determination of aromatic hydrocarbon types in middle distillates-high performance liquid chromatography (HPLC) method with refractive index detection” is used as the arbitration method of China for PAHs determination in vehicle diesel fuel. However, a series of problems have been exposed during the PAHs determination for some vehicle diesel fuel samples, including inconsistent separation sequences with different columns, poor system stability, and severe overlap of monocyclic and bicyclic aromatic hydrocarbons, which make it difficult to accurately determine the PAHs. In this work, experimental and theoretical analysis were carried out to solve the above those problems, the chromatographic column was classified by improving the SPS (system performance solution), and the appropriate type of HPLC column for PAHs determination was selected. With the verification of several laboratories, it has been demonstrated that this solution can significantly improve the accuracy of PAHs determination and increase the system stability, and it can meet the precision requirements of SH/T 0806-2008.

COMMERCIAL APPLICATION OF HIGH HARDNESS AND AMMONIA NITROGEN WASTEWATER TREATMENT TECHNOLOGY FOR COAL GASIFICATION

2022, 53(2):  123-126. 

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It is of great significance for the development of coal chemical industry to solve the standard treatment of high hardness and high ammonia nitrogen wastewater produced from coal gasification for hydrogen production. According to the characteristics of sewage, the combined process of chemical hardness reduction with biological decarbonization and nitrogen removal was adopted in a refinery. The results of unit running indicated that the average removal rates of COD, NH3-N, total nitrogen were stable at above 90.8%, 98.5%, 92.9%, respectively, which could meet the requirement of special discharge limit in the national standard “Emission standard of pollutants for petroleum refining industry(GB 31570—2015)”. The long-term stable operation of the designed water load of 140% has been realized. The experience can be used for reference in similar wastewater treatment.

COMMERCIAL APPLICATION OF CATALYTIC DEEP REDUCTION TECHNOLOGY FOR REFINERY BIOCHEMICAL EXCESS SLUDGE

2022, 53(2):  127-130. 

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It is of great significance to reduce the sludge treatment and disposal cost and protect the ecological environment. The effect of industrialized treatment of refinery biochemical excess sludge was studied by using SMR unit. The operation results showed that the biochemical excess sludge with the water content of 98.3% was treated by SMR unit, the dewatering performance of sludge was improved significantly, the average water content of residue was 57.1%, the sludge amount was reduced by 99.4%, the average VSS removal rate was 78.3%, the BOD₅/COD ratio of digestion liquid was 0.31, and the deep reduction of sludge were realized.