Table of Content

12 July 2025, Volume 56 Issue 7

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STUDY ON INCREASING ELECTRIFICATION RATE IN NEW LARGE ETHYLENE PLANTS

2025, 56(7):  1-7. 

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Under the dual-carbon targets,utilizing green electricity and improving electrification rate constitute crucial pathways for reducing carbon emissions in ethylene plants. This study investigates the feasibility of electrification of some steam users in newly constructed large-scale ethylene plants through comprehensive analysis of equipment technology, process operational stability, carbon dioxide emissions, and economy. The results show that:  Current electrical equipment technologies exhibit sufficient maturity for practical implementation; After the electrification rate is improved, the stability of the process operation depends more on the power supply quality; Utilizing green electricity, elevating electrification rate from 14.8% to 34.7% could reduce CO₂ emissions by 510 kt/a;  Economic analysis indicates that the internal rate of return (IRR) of electrification rate enhancement schemes exhibits high sensitivity to fuel gas and electricity prices, while achieving a higher IRR under carbon tax scenarios. Considering ethylene plants' leading role in petrochemical systems, increasing the electrification rate needs to be gradual according to the specific situation in practical projects.It is technically and economically feasible to increase the electrification rate of ethylene plants under the premise of fully guaranteeing the stability of power supply, which is helpful to reduce carbon emissions.

DIFFERENCE ON HYDRODEMETALIZATION REACTION CHARACTERISTICS FOR DIFFERENT KINDS OF RESIDUE FEEDSTOCK

2025, 56(7):  8-12. 

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Using Feedstock A with high nickel(Ni) content and low vanadium(V) content (Ni and V mass fractions of 36.6 μg/g and 19.2 μg/g, respectively) and Feedstock B with low Ni content and high V content (Ni and V mass fractions of 23.8 μg/g and 83.0 μg/g, respectively), fixed bed residue hydrotreating experiments were carried out on the same fixed bed hydrotreating pilot-test unit with the same catalyst gradation under the conditions of a liquid-hour volume space velocity of 0.23 h^-1, a hydrogen partial pressure at the reactor inlet of 15.0 MPa, a hydrogen oil volume ratio of 700, and an average reaction temperature of 375.5 ℃. The results demonstrated that Feedstock B achieved superior hydrodemetallization performance. Compared with Feedstock A, Feedstock B showed higher Ni,V and (Ni+V) removal efficiency by 4.00,8.71 and 9.41 percentage points,respectively. This trend was corroborated in industrial operations when comparing Unit U1 processing high Ni content and low V content residue with Unit U2 processing low Ni content and high V content residue. U2 exhibited higher Ni removal by 4.52 percentage points, higher V removal by 8.18 percentage points, and higher total metal removal by 9.52 percentage points than U1,respectively. To enhance hydrodemetallization efficiency in fixed-bed residue hydrotreating, two strategic approaches are recommended: Laboratory development of catalysts and grading systems with enhanced conversion capability for resins and asphaltenes, followed by industrial implementation; Operational optimization through preferential processing or appropriate blending of feedstocks with lower Ni/V mass ratio or higher aromaticity in commercial units.

FABRICATION AND CHARACTERIZATION RESEARCH ON HIGH-ASPHALT-CONTENT EMULSIFIED ASPHALT BASED ON CATASTROPHIC PHASE INVERSION

2025, 56(7):  13-23. 

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Increasing the asphalt content in asphalt emulsion can effectively improve the road performance of asphalt mixtures. Based on this, the phase inversion method was adopted to prepare high-asphalt-content asphalt emulsions (HIACEs) with an asphalt mass fraction greater than 75%. The preparation process and the influence mechanisms of HIACEs' performance were studied through dispersibility tests, conductivity tests, particle size tests, storage stability tests, and residue evaporation tests. The results showed that the maximum asphalt mass fraction that could be "accommodated" in water-in-oil HIACEs was 96%. With the increase in asphalt content, emulsifier dosage, stirring time, and stirring rate, the average particle size of HIACEs decreased and stabilized, while the storage stability gradually improved. Orthogonal experiments further determined that the order of influence of preparation process conditions on HIACEs' performance decreased following: asphalt content > emulsifier content > stirring rate. The optimal preparation conditions for HIACEs were:an asphalt mass fraction of 89%, an emulsifier mass fraction of 4%,a stirring time of 10 min, and a stirring rate of 1000 r/min. The research results provide a theoretical foundation and technical support for the production and application of HIACEs.

ANALYSIS AND COUNTERMEASURES OF LONG TERM OPERATION PROBLEMS IN A HYDROGEN PRODUCTION UNIT

2025, 56(7):  24-31. 

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A detailed analysis was conducted on the causes of problems such as flower spots on the conversion furnace tubes, rapid decrease in heat transfer efficiency of the waste heat boiler, and overheating of the medium temperature shift reactor bed in a domestic natural gas hydrogen production unit, and corresponding solutions were proposed. The results showed that the main reasons for the occurrence of flower spots in the converter tube include：①high sulfur and chlorine impurity content in the feed gas, ②low processing load of the device and frequent adjustment of the device processing capacity, ③improper catalyst loading, resulting in "bridging" phenomenon, ④catalyst coking, ⑤improper adjustment of the converter furnace nozzle, ⑥the impact of rapid heating/cooling speed on the strength of the conversion catalyst during repeated start-up and shutdown processes. The reason for the rapid decrease in heat transfer efficiency of the waste heat boiler is that the anti-coking additive K2O in the catalyst is taken away to form scaling, resulting in a decrease in heat transfer rate.The rapid decrease in heat exchange efficiency of the waste heat boiler is the main reason for the bed overheating of the medium temperature shift reactor. To address these issues, measures such as strictly controlling the frequency and rate of load adjustment, controlling the rate of change in feed gas flow rate and temperature rise/fall rate, optimizing the combustion state of the converter, implementing medium pressure steam thermal circulation, and injecting water into the inlet of the medium temperature shift reactor are proposed. The comprehensive implementation of the above measures can ensure the continuous and stable operation of the hydrogen production unit.

STUDY ON BLOCKING OF LIQUID DISCHARGE LINE OF AIR COOLER IN STYRENE UNIT

2025, 56(7):  32-38. 

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Styrene monomer is active and liable to form polymer by polymerization reaction. The fouling of styrene polymer is an important factor affecting the long cycle operation of styrene plant. By analyzing the process of styrene production and the principle of ethylbenzene dehydrogenation reaction, and analyzing the blockage in the drain line of the air cooler in the dehydrogenation process in detail, it is found that the reason of the blocking in the drain line of the air cooler is caused by stilbene crystallization. The existence of stilbene, a by-product of ethylbenzene dehydrogenation, and its influence on the blocking of styrene unit were systematically proposed. According to the properties of stilbene and the experience in the production process, the countermeasures and solutions for the crystallization blocking of the air cooler discharge pipeline were put forward, which could provide theoretical guidance and practical reference for the long-term stable operation of styrene unit.

APPLICATION AND COMPARATIVE STUDY ON EBULLATED BED FILTRATION TECHNOLOGY FOR DMTO AND SMTO QUENCH WATER

2025, 56(7):  39-48. 

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In order to solve the problem of blockage of production equipment caused by high concentration of fine catalysts in MTO quench water, an ebullated bed filtration (EBF) unit was developed and successfully applied to MTO water system by combining deep filtration and cyclone enhanced desorption technology. Compared with the DMTO unit, the suspended solids content of the quench water in the SMTO unit is higher, the catalyst particle size is smaller and the dispersion is better. Although it is not easy to block, it is more difficult to separate. For the quench water of the DMTO unit, when the suspended solids content in the influent is 400—800 mg/L, the first-stage filtered effluent is reduced to 16—102 mg/L, and the second-stage filtered effluent is reduced to 7—16 mg/L. For the quench water of SMTO unit, when the suspended solids content in the influent is 4 500—9 500 mg/L, the effluent of primary filtration is reduced to 100—862 mg/L, and the effluent of secondary filtration is reduced to 13—160 mg/L. The EBF unit uses discharged quench water to regenerate the filtration medium without additional consumption of fresh water. The excellent separation effect of suspended solids greatly improves the reuse rate of quench water, reduces the cleaning frequency of heat exchange equipment and the cost of production and operation, and provides strong support for the efficient operation of methanol to olefins process.

APPLICATION OF MEMBRANE SEPARATION TECHNOLOGY IN RECOVERING HYDROGEN FROM HYDROGEN-RICH DRY GAS IN REFINERY

2025, 56(7):  49-55. 

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The technical principle, process flow and practical application of two new sets of dry gas hydrogen recovery facilities using membrane separation technology in a refinery were introduced. According to the calibration results, the recovery rate of hydrogen is above 90%, and 29 008 tons of hydrogen can be recovered every year, with a benefit of 98.83 million Yuan. At the same time, the heat value of fuel gas in the whole plant pipe network is improved, the fluctuation is reduced, the operation of the plant is stabilized, and the competitiveness of the refinery is enhanced.

RESEARCH AND DEVELOPMENT OF CATALYTIC CRACKING CATALYST RICH IN INTERCONNECTED MESO-MACRO PORES

2025, 56(7):  56-61. 

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A new catalytic cracking (FCC) catalyst rich in interconnected meso-macro pores has been developed by SINOPEC Research Institute of Petroleum Processing Co., Ltd., basing on the new developed alumina matrix and catalyst preparation technology, which solves the problem of the mutual constraint between abundant meso-macro pores and excellent strength of catalyst. The results of physical and chemical properties show that compared with the catalyst using conventional alumina matrix, the new catalyst has larger pore volume and better diffusion performance, the pore volume increased from 0.37cm³/g to 0.45 cm³/g, the 5—100 nm pore proportation increased from 16% to 52%, and has excellent pore inter-connectivity. The evaluation results of catalytic cracking reaction using heavy feedstock show that the new catalyst could achieve higher light oil product yields, lower heavy oil and coke yields than the comparative catalyst, providing technical support for improving the efficient conversion of inferior feedstocks.

APPLICATION OF Fe-Ni BIMETALLIC NANOEMULSION CATALYST IN SLURRY-PHASE HYDROCRACKING OF COAL TAR

2025, 56(7):  62-68. 

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Water in oil (W/O) type Fe-Ni bimetallic nanoemulsions were prepared as the dispersed catalysts, and their catalytic performance in the slurry-phase hydrocracking of coal tar atmospheric residue was investigated. The results demonstrated that the nanoemulsion with transparent appearance and stable kinetics was obtained at surfactant dosage of 10%. The dispersed phase was distributed uniformly in the range of 5 - 30 nm, with an average particle size of approximately 10.5 nm. The active phase of the nanoemulsion catalyst after in-situ sulfurization is mainly Fe4.5Ni4.5S8 mixed crystal, with an average particle size of 328 nm, distributed in the range of 125 - 425 nm. During the coal tar hydrocracking process, the catalytic performance of the Fe-Ni bimetallic catalyst is better than that of the Fe or Ni single metal catalysts, which is attributed to the synergistic effect of Fe-Ni bimetals. The activity of Fe-Ni bimetallic nanoemulsion catalyst is close to that of oil-soluble catalyst, realizing the advantage combination of high activity of oil-soluble catalysts and low cost of water-soluble catalysts.

COMMERCIAL APPLICATION OF MULTIFUNCTIONAL LIGHT OLEFIN-BOOSTING ADDITIVE COMP IN CATALYTIC CRACKING UNIT

2025, 56(7):  69-76. 

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The first commercial application of COMP additive for boosting lighe olefins in a catalytic cracking unit with capacity of 1.8 Mt/a is introduced. The COMP additive accounts for 8% of the inventory. Compared with the blank test, the yield of LPG and propylene increased by 2.50 and 1.35 percentage points, respectively, the yield of gasoline decreased by 2.11 percentage points, the yield of diesel and slurry oil decreased by 0.55 and 0.20 percentage point, respectively, furthermore the selectivity of coke decreased by 0.13 percentage point. The results indicate that the unit achieved the trial target of and significant economic benefits after COMP additive application.

DEVELOPMENT AND ADSORPTION KINETICS OF LIQUID PHASE DECHLORINATOR FOR REFORMATE OIL

2025, 56(7):  77-82. 

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Utilizing the “one pot method” with molecular sieve and Na₂CO₃ as the principal components, along with the addition of a binder and other substances, a layer-type of reformate oil liquid-phase dechlorinating agent was fabricated. The dechlorinating agent exhibited a chlorine capacity of 16.37% and a strength reaching 87 N/cm. Moreover, no sludging phenomenon was observed even after 24 hours of water immersion, thereby fulfilling the requirements for industrial application.Long-term industrial sideline comparison tests were conducted, and the results demonstrated that the dechlorination effect achieved by the self-made dechlorinating agent surpassed that of the imported agent, indicating its promising potential for industrial application. Through X-ray diffraction (XRD), N₂ adsorption-desorption, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR) analyses of the dechlorinating agent both before and after the reaction, it was found that the lamellar structure and the abundant active sites of Na₂CO₃ within its internal structure were favorable for the processes of adsorption and dechlorination.Furthermore, an adsorption kinetic study on the adsorption process of the dechlorinating agent was carried out. The findings revealed that the adsorption process conformed to the pseudo-second-order kinetic model, signifying that the adsorption process was predominantly a chemisorption-based adsorption process.

RESEARCH ON THE RELATIONSHIP BETWEEN CATALYST MORPHOLOGY AND CRUSHING STRENGTH

2025, 56(7):  83-89. 

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The influence of support morphology on crushing strength was investigated using various methods. The results indicated that the crushing strength of the support has a certain distribution range, which conforms to a normal distribution. The crushing strength values, and corresponding morphological parameters were obtained using the Weibull analysis method. The impact of morphology on the extrusion of dry strips and the crushing strength of the support was also studied. It was found that the square-shaped columnar support had the highest strength, while the triangular support had the lowest. The proportion of the real part was not the key determinant of strength; instead, morphology had a significant impact on strength. Finite element analysis was employed to simulate the stress distribution during the compression process of supports with different morphologies, revealing that the low strength was due to structural collapse caused by local stress concentration.

FLUID DISTRIBUTION PERFORMANCES IN SCALLOP FOR RADIAL BED REACTOR

2025, 56(7):  90-98. 

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The C₈ aromatics isomerization is an important reaction process for the production of p-xylene. This process is typically carried out in a radial bed reactor, with the scallop which is a key internal component of the radial bed reactor, playing a significant role in achieving uniform fluid distribution. A combination method of cold model experiments and computational fluid dynamics (CFD) simulation was used to analyze the pressure drop and flow field distribution inside the scallop. By comparing the experimental data with the simulation data,it was found that the relative error between the pressure drop inside the scallop and the average outlet velocity of the side holes under different gas velocities was less than 15%, which validated the accuracy of the established scallop simulation model. The influence of inlet gas velocity on the fluid flow characteristics inside the scallop was investigated, and it was found that the fluid distribution patterns were essentially consistent under different gas velocities. The gas velocity in the perforated section of the scallop is symmetrical along the circumference, with the gas velocity in the middle hole slightly lower than that in the two side holes. Due to the presence of the jet zone, the static pressure inside the scallop shows a trend of decreasing first and then increasing along the axial direction from top to bottom.

INFLUENCE OF REMOVING LIGHT COMPONENTS DURING FCC SLURRY THERMAL POLYCONDENSATION REACTION PROCESS ON THE FORMATION AND PROPERTIES OF MESOPHASE PITCH

2025, 56(7):  99-106. 

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Mesophase pitches with different crystal structures were prepared from FCC slurry by thermal polycondensation and nitrogen blowing process. The light component removal rate was regulated by changing the reaction temperature, reaction time, and nitrogen flow rate. The influence of removing light components on the formation and development of mesophase structure was investigated. The results showed that pressurized treatment at the early stage gives an opportunity for small molecules to react into precursor pitch, and nitrogen blowingat the subsequent stage drives the rapid concentration of the precursor pitch into mesophase spheres of the appropriate size and coalescence into mesophase pitch with excellent optical texture by efficiently removing the residual light components and low-boiling point isotropic components. The removal rate of light components can be increased by increasing the reaction temperature, reaction time and nitrogen flow rate.The increase in the removal rate of light components increased the mesophase content and promoted the formation of a ‘broad domain’ mesophase structure, which increased the size of the thickened cyclic aromatic hydrocarbon molecules of mesophase pitch and improved the orderly arrangement of the microcrystalline structure.

DISTRIBUTION OF CATALYTIC PYROLYSIS PRODUCTS OF POLYOLEFIN PLASTICS

2025, 56(7):  107-118. 

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To enhance the utilization rate and added value of waste plastics, the effects of catalyst type, protective gas atmosphere, reaction temperature, and pressure on the product yield and the composition of gas and liquid products of cracking reaction of polypropylene (PP) and mixed plastics (PP-HDPE-PS) were investigated using a high-pressure autoclave reactor. The results showed that both PP and PP-HDPE-PS achieved oil and gas yields exceeding 94% by mass, with liquid products predominantly composed of gasoline fractions. Water vapor atmosphere was conducive to the generation of liquid products of PP and mixed plastics cracking, and the catalyst was conducive to the generation of gas products. The yield of PP cracking liquid products increased first and then decreased with the increase of temperature, and decreased with the increase of reaction pressure. Under the combined action of water vapor and S-type FCC catalyst, the content of aromatics in PP liquid product was multiplied, and the generation of olefin was inhibited. For the cracking reaction of mixed plastics, the coke formation could be inhibited by steam atmosphere, and the total yield of benzene, toluene, ethylbenzene and xylene (BTEX) could exceed 29%.

STUDY ON ADSORPTION CHARACTERISTICS AT THE SILICON CARBIDE/ASPHALT INTERFACE BASED ON MOLECULAR DYNAMICS SIMULATION

2025, 56(7):  119-127. 

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To investigate the adsorption characteristics of silicon carbide (SiC) particles on asphalt, molecular dynamics simulations were employed to construct models of matrix asphalt, SiC, and the SiC/asphalt interface. The rationality of the constructed models was validated through density, energy, and radial distribution functions. The interfacial energy of the SiC/asphalt interface was analyzed at different temperatures, and the diffusion characteristics and selective adsorption of asphalt components at the interface were examined at 298 K. The simulation results were further verified by a four-component asphalt test. The results indicate that the absolute value of interfacial energy first increases and then decreases with rising temperature, reaching its maximum at 298 K. At this temperature, lighter components (saturates and aromatics) and resinsexhibit better diffusion at the SiC/asphalt interface. SiC demonstrates selective adsorption towards asphalt components, with significant accumulation of resins and lighter components at the interface. The four-component asphalt test results show that the relative contents of saturates, aromatics, and resins decrease in the SiC-modified asphalt, while the relative content of asphaltenes increases. This suggests that the selective adsorption of SiC on the four asphalt components enhances the viscosity and stiffness of asphalt, providing a theoretical basis for the study of asphalt pavement performance.

SIMULATION STUDY ON SHORT-CYCLE OPERATION OF p-XYLENE PURIFICATION UNIT

2025, 56(7):  128-135. 

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A model was established to simulate the process of p-xylene adsorption and separation on a moving bed to study the effects of the cycle period and the reflux ratios of each area of the adsorption tower on the adsorption performance of the adsorption and separation process. The simulation results show that: keeping the reflux ratio of each region unchanged, with the gradual shortening of the cycle period, the production WHSV is greatly increased, the purity of paraxylene and the yield indexes are gradually reduced, and when the cycle period is more than 24 min, the paraxylene product can still maintain a higher purity, and the yield is slightly reduced; to continue to shorten the cycle period, the reflux ratio of each region needs to be adjusted to ensure the purity of the product. Under the premise of ensuring product purity, the maximum production WHSV was obtained at a cycle time of 17.6 min, but at this time, the yield was lower at 82.2%, and the desorbent dosage per unit of product was about 19.9% higher than that at a cycle time of 32 min.

STEADY STATE AND DYNAMIC SIMULATION OF C₈ AND C₉ AROMATIC HYDROCARBONS SEPARATION FROM REFORMATE GASOLINE

2025, 56(7):  136-146. 

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For the renovation project of C₈ and C₉ aromatic hydrocarbon distillation units, simulation design was carried out using conventional two tower process and distillation tower process with side lines, and non dominated sorting genetic algorithm was used to optimize the process. Firstly, simulations were conducted on the conventional two tower process for the C₈ and C₉ removal towers. When the purity (w) indicators of C₈ and C₉ products were required to be 0.98 and 0.9999, respectively, the total heat load of the conventional two tower process reboiler was calculated to be 33.52 MW. Then, the conventional two tower process was optimized, and the total heat load of the optimized two tower reboiler was 23.40 MW. Furthermore, a single-sided line extraction process and a double-sided line extraction process were constructed separately, and the steady-state structure of the distillation tower was optimized. It was found that, while meeting the purity requirements, the total heat load of the reboiler using both single-sided and double-sided distillation processes was significantly reduced, to 21.86 MW and 21.55 MW, respectively. Finally, the single-sided process with better structural controllability was selected, and simulations were conducted for temperature dynamic control structure and temperature side flow ratio dynamic control structure. The results showed that both the temperature control structure and the temperature side line proportional control structure can effectively cope with dynamic control of feed flow rate ±10% disturbance and feed composition (w) ±5% disturbance, while the steady-state deviation of the temperature side line proportional control structure was smaller.

FAULT DIAGNOSIS METHOD FOR CRUDE OIL NEAR-INFRARED SPECTROSCOPY ANALYSIS SYSTEM BASED ON ENSEMBLE CSSOA-SVM

2025, 56(7):  147-152. 

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To address the challenges of local optima, high-dimensional feature, and insufficient diagnostic accuracy in fault diagnosis of crude oil near-infrared (NIR) spectroscopy analysis system, an ensemble CSSOA-SVM-based fault diagnosis method is proposed. The chaos sparrow search optimization algorithm (CSSOA) is introduced to optimize the support vector machine (SVM) parameters, overcoming the local optima limitations of the traditional sparrow search algorithm (SSA) while preserving its rapid convergence, thus enhancing classification performance. By integrating the AdaBoost algorithm, multiple CSSOA-SVM base classifiers are combined, with dynamic adjustments to sample and classifier weights improving the recognition accuracy and robustness for complex fault patterns. Experimental results demonstrate that the proposed ensemble CSSOA-SVM model achieves a diagnostic accuracy of 95.48% across six common fault types, outperforming traditional methods in accuracy, convergence speed, and robustness, offering an effective solution for fault diagnosis in crude oil NIR spectroscopy analysis system.

TRIBOLOGICAL PROPERTIES AND ELECTRICAL CONDUCTIVITY OF COMPOSITE LITHIUM GREASE REINFORCED BY IONIC LIQUID MODIFIED GRAPHITE

2025, 56(7):  153-161. 

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Using pentaerythritol ester as base oil, lithium complex soap as thickener, and adding ionic liquid modified graphite with different chain lengths as additives, lithium complex grease was prepared. The corrosivity and volume resistivity of the grease were tested. The tribological properties under current-carrying and non-current-carrying conditions were determined by using high-speed reciprocating friction and wear tester. The worn surfaces were analyzed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results show that the modified graphite material improves the wear resistance and conductivity of the base grease. Ionic liquids with longer chains form denser chemical films and exhibit the best friction reduction and anti-wear properties. Ionic liquids with shorter chains have lower volume resistivity and the best conductivity due to reduced electron entanglement.

INFLUENCE OF MOLECULAR STRUCTURE OF AMIDE SOAP-BASED THICKENERS ON PERFORMANCE OF LUBRICATING GREASES

2025, 56(7):  162-171. 

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Amide soap-based grease exhibits excellent properties such as high-temperature stability, oxidation stability, mechanical stability, radiation resistance, and long service life. To investigate the influence of molecular structure of amide soap-based thickeners on grease performance, four types of N-octadecyl terephthalamate metal salt thickeners and four sodium-based N-alkyl terephthalamate thickeners with varying hydrocarbon chain lengths were synthesized, and corresponding greases were prepared. The grease properties including penetration, dropping point, oil separation rate, and tribological performance were evaluated to explore the relationship between the molecular structure of amide soap-based thickeners and grease characteristics. Results indicate that the performance of amide soap-based grease demonstrates regular variations with changes in the atomic number of metal ions and hydrocarbon chain length. A soap-soap dimer model was established using molecular simulation methods to preliminarily discuss the influence mechanism of thickener molecular structure on grease properties.

COMPARASION ON TREATMENT TECHNOLOGIES OF SULFUR-CONTAINING SPENT CAUSTIC FROM Mt/a GRADE ETHYLENE PLANT

2025, 56(7):  172-178. 

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At present, mature technologies on the treatment of sulfur-containing spent caustic from million-ton ethylene plants included state-owned wet oxidation technology, imported wet oxidation technology, combination of catalytic oxidation and bioaugmentation technology. Analysis showed that both wet oxidation technologies had excellent treatment effects on thiols and sulfides of ethylene spent caustic, and further the state-owned wet oxidation technology had a higher treatment efficiency, with a COD removal rate of 96.3%. In comparison, the COD removal rate of catalytic oxidation technology was only 81.1%, and GC-MS analysis showed that the effluent from catalytic oxidation still contained a large amount of organic sulfur compounds, while the direct treatment of ethylene spent caustic by bioaugmentation technology had problems such as low treatment efficiency and difficult treatment of odorous gases. Cost and economic analysis showed that state-owned wet oxidation technology had the advantages of high treatment efficiency, low operating costs, low equipment investment costs, and had great promotion and application value.

COMMERCIAL APPLICATION OF COKE POWDER REMOVAL TECHNOLOGY FOR SULFUR-CONTAINING WASTEWATER FROM DELAYED COKING UNIT

2025, 56(7):  179-185. 

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In light of the inadequate treatment effectiveness exhibited by contemporary technologies in eradicating oil and coke powder from sulfur-containing wastewater, a phenomenon that has given rise to challenges concerning coking and blockage within downstream stripping units, this study proffers a novel chemical-free pretreatment process, predicated on the "cyclone dissolved air flotation + coalescence oil removal" technology. This process is further augmented by filtration mechanisms that are designed for the elimination of coke powder, thereby functioning as a pretreatment for the stripping apparatus. The experimental results demonstrate that, during the non-small steam blowing phase, the process achieves an average oil removal efficiency of 98.93%.The average mass concentration of suspended solids at the outlet is 7 mg/L. This is calculated using the average mass concentration of suspended solids at the inlet, which is 353 mg/L. In the small steam blowing phase, oil removal efficiency and suspended solids removal rate have been improved to different degrees. It is also notable that high-quality light pollution oil can be recycled and reused, providing a valuable reference for the effective treatment of similar wastewater.

APPLICATION OF RISK-BASED INSPECTION (RBI) TECHNOLOGY IN HYDROGENATION UNIT

2025, 56(7):  186-194. 

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In recent years, with the crude oil processed by domestic refineries has gradually deteriorated, and the content of corrosive elements such as Cl, N and S in the feedstocks used in the hydrogenation system has gradually increased, which has led to an increase in the number of corrosion failures caused by ammonium salts in hydrogenation units.Based on the historical failure cases of hydrogenation systems, the corrosion locations and corrosion mechanisms, and formulates the risk level of the equipment under different operating conditions were summarized using risk based inspection(RBI) technology.Then, the gas oil hydrogenation system of a factory was taken as the research object, and the corrosion circuit division and risk assessment of the equipment and pipelines prone to ammonium salt (NH₄Cl, NH₄HS) corrosion were carried out. At the same time, ideal control ranges are set for various indicators of different corrosion unit circuits in the system to control or slow down the occurrence of ammonium salt corrosion.

RESEARCH PROGRESS ON SELECTIVE HYDROGENATION OF CYCLODODECATRIENE

2025, 56(7):  195-200. 

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Cyclododecene holds significant application value in the fields of high-performance materials and fine chemicals, and its efficient production is crucial for fields such as those in specialty nylon manufacturing. The selective hydrogenation of 1, 5, 9-cyclododecatriene (abbreviated as cyclododecyltiene) is the key pathway for cyclododecene synthesis, with the optimization of catalysts and processes being the primary focus for improving yield and reducing production costs. This review presents recent progress on selective hydrogenation of cyclododecatriene to cyclododecene, primarily introducing the reaction mechanism, comparing the advantages and disadvantages of different technologies, and the reaction performance of various catalysts. The existing problems and challenges in the selective hydrogenation of cyclododecatriene to cyclododecene are also analyzed. Finally,this paper concludes with some concluding remarks on the future development of selective hydrogenation of cyclododecatriene for the production of cyclododecene.