Table of Content

12 September 2024, Volume 55 Issue 9

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DEVELOPMENT AND COMMERCIAL APPLICATION OF TAILORED START-UP CATALYST FOR RESID TO CHEMICALS UNIT

2024, 55(9):  1-7. 

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Based on the process characteristics and product distribution of resid to chemicals (RTC) unit, while considering the demands for the fluidization performance and physicochemical properties of the start-up catalyst, a scientific blend of selected equilibrium catalyst component, customized fresh component, and inert auxiliary was developed to create the tailored start-up catalyst TSC-R1. Compared to traditional start-up catalyst, the tailored start-up catalyst has excellent physical properties, higher propylene factor and lower coke selectivity, and can quickly match the start-up requirements of the target plant, enhancing the economic benefits of the RTC unit. The industrial application of TSC-R1 in SINOPEC Anqing Petrochemical Company 3.00 Mt/a RTC unit showed that the adjustment time of the unit was greatly shortened, and the time for the unit to achieve stable operation was only 7 d. The quick and stable reaction activity of the catalyst is helpful for the product distribution of the unit to reach the design condition and ensures economic benefits.

ANALYSIS OF SPENT CATALYST IN INDUSTRIAL FIXED-BED RESID HYDROTREATING UNIT AFTER LONG TERM OPERATION

2024, 55(9):  8-12. 

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The spent catalyst in a domestic resid hydrotreating unit after long-term operation was collected , and a comprehensive analysis was conducted. The deposition of Ni and V on the catalyst in the unit showed a trend of first increasing and then decreasing along the flow direction, and mainly deposited on the HDM catalyst in the reactors R1-R3. The R1-HDM3 catalyst had the highest Ni and V deposition, reaching 31.3% and 92.2%, respectively. Fe and Ca were mainly deposited on the protective agent. The amount of carbon deposits decreased gradually along the flow direction, and mainly deposited on the R1 catalyst. The deposition of Ni in the catalyst was relatively uniform, Fe and V tended to deposit in the pore, and the distribution of sulfur was highly correlated with that of V.After a long period of operation, the pores of resid hydrotreating catalysts, especially the demetallization catalysts,are seriously blocked by deposited metals, thus reducing their activity.

SYNTHESIS OF FUNCTIONAL GROUP MODIFIED UiO-66 SUPPORTED Rh CATALYST AND ITS CATALYTIC PERFORMANCE FOR CO2 HYDROGENATION TO ETHANOL

2024, 55(9):  13-23. 

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The hydrogenation of carbon dioxide (CO₂) to ethanol and other value-added chemicals is one of the important routes to achieve "dual-carbon" goals economy. Rh-based catalysts supported on UiO-66 modified with different functional groups (—OH and —NH₂) were prepared, their catalytic performance for CO₂ hydrogenation was tested in a batch reactor, and the effect of functional group modification on the performance of Rh-based catalysts for CO₂ hydrogenation was investigated by XRD, SEM, TEM, FT-IR, ICP, BET, TG, CO pulse, XPS and CO₂-TPD. The results showed that the catalytic performance of the catalyst modified with functional groups was significantly enhanced compared with that of Rh/UiO-66 catalyst. In particular, the Rh/UiO-66-NH₂ catalyst modified with —NH₂ exhibited excellent catalytic activity, ethanol selectivity and catalytic stability; while the Rh⁺ content in catalyst increased obviously after —NH₂ modification, which was beneficial to the stabilization of CO*, C-C coupling and hydrogenation with CH_x* were promoted to produce ethanol. At the pressure of 3.0 MPa and the temperature of 250 ℃, Rh/UiO-66-NH₂ exhibited the highest catalytic activity (5.6%) and ethanol selectivity (84.7%) with basically unchanged catalytic performance after five cycles.

EFFECT OF METAL AND ZEOLITE COMPATIBILITY ON THE CATALYTIC DEHYDROGEANTION OF ETHANE

2024, 55(9):  24-32. 

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It is important to develop cheap, environmentally friendly and efficient transition metal molecular sieve system for catalytic dehydrogenation of ethane in order to supplement the traditional petroleum route for olefin production. Metal ions anchored to Br?nsted acid sites in zeolite by ion exchange method showed unique C—H and C—C bond-selective activation. The effects of the compatibility of a series of transition metals (Fe, Co, Ni, Cu, Zn and Mn) with different types of molecular sieves (MOR, β, Y, MCM-22, MCM-41, SAPO-11, SAPO-34, USY and ZSM-5) on the catalytic dehydrogenation of ethane were investigated by ion exchange method. The results of X-ray diffraction, ultraviolet and visible spectrophotometry and H2-temperature programmed reduction characterizations showed that the metal ions at the Bronsted acid site were highly dispersed and resistant to reduction. The experimental results and density functional theory calculations showed that Co had excellent potential for selective activation of C—H bonds, but the product distribution still depended on the type and properties of molecular sieve. The selectivity of ethylene could be close to 100% on the zeolite with suitable pore size, otherwise the dehydrogenated products were prone to secondary reaction at the remaining Bronsted acid site to form aromatics and carbon deposits.

SYNTHESIS OF ORDERED MESOPOROUS CARBON SUPPORTED Pt-MoOx CATALYST AND ITS CATALYTIC PERFORMANCE FOR METHYLCYCLOHEXANE DEHYDROGENATION

2024, 55(9):  33-41. 

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Using ordered mesoporous carbon (CMK-3) as a carrier, yPt/CMK-3 and MoO_x additive-modulated catalyst yPt-zMoO_x/CMK-3 (y and z are the number of deposition cycles of Pt and MoO_x, respectively) were prepared by atomic layer deposition technology. The impact of the number of deposition cycles on the dispersion of the Pt metal and the catalytic performance for the dehydrogenation of methylcyclohexane was studied. The results showed that optimal Pt dispersion and an appropriate amount of atomically dispersed MoO_x additives could significantly improved the performance of Pt-based catalysts. Compared with 10Pt/CMK-3, the dehydrogenation rate (amount of H₂ produced per unit mass of Pt per unit time) on the catalyst 10Pt-1MoO_x/CMK-3 increased from 79.02 mol/(g.h) to 97.88 mol/(g.h), and the methylcyclohexane conversion rate increased from 71% to 91%. The addition of MoO_x additive had little effect on the dispersion of Pt nanoparticles, mainly increased the electron density on the Pt surface and decreased the activation temperature of catalyst. In addition, the MoO_x additives can promote the desorption of H₂ on the catalyst surface through hydrogen overflow, thus increasing the yield of H₂. The research provides a theoretical basis for the design of efficient methylcyclohexane dehydrogenation catalysts.

THERMODYNAMIC ANALYSIS ON HYDRODEALKYLATION REACTION OF C₉+ HEAVY AROMATIC HYDROCARBON

2024, 55(9):  42-51. 

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Two kinds of typical C₉+ heavy aromatic hydrocarbon feedstocks were selected for hydrocarbon composition analysis. The analysis results showed that trimethylbenzene and ethyltoluene were the major component in the C9+ heavy aromatic hydrocarbon feedstocks. Therefore, trimethylbenzene and ethyltoluene were selected as model compounds to calculate the standard molar reaction enthalpy change, standard molar Gibbs free energy change, and standard equilibrium constant of the hydrodealkylation reactions in the temperature range of 350-650 ℃, and the thermodynamic calculation results of dealkylation reaction were analyzed. The results indicated that the hydrodealkylation reactions of trimethylbenzene and ethyltoluene were exothermic reaction within the temperature range of 350-650 ℃, and the exothermic energy of the reactions was negatively correlated with the symmetry of the molecular structure, which might be related to overcoming the steric hindrance of methyl or ethyl groups. The dealkylation of trimethylbenzene and ethyltoluene can be carried out spontaneously in standard conditions, meanwhile the equilibrium constants of the reactions gradually decreases with the increase of reaction temperature.

EFFECT OF NOZZLE ARRANGEMENT ON GAS-SOLID FLOW CHARACTERISTICS AND HEAT AND MASS TRANSFER INSIDE THE RISER

2024, 55(9):  52-61. 

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Good interphase heat and mass transfer and gas-solid flow characteristics in the catalytic cracking riser can provide a favorable reaction environment for the catalytic cracking unit. The effects of 4 different nozzle arrangements on gas-solid flow characteristics and heat and mass transfer in the riser of a 1.80 Mt/a FCC unit were studied by numerical simulation. The simulation results showed that the distribution of solid holdup of catalyst and oil-gas in the riser of arrangement B with 8 nozzles and 30° nozzle inclination was better than other arrangements;the heat transfer between phases in the riser was very rapid, the temperature distribution of gas-liquid-solid three-phase was almost the same under 4 nozzle arrangements, and the distribution of feedstock oil droplets was relatively uniform in arrangement B. Through the evaluation of feedstock oil droplet evaporation, it is found that arrangement B has the best evaporation effect, which is beneficial to the FCC reaction and the improvement of product distribution.

CHARACTERISTICS OF FALLING FILM FLOW ON SHELL SIDE OF TUBE-WOUND HEAT EXCHANGERS WITH ROUND AND FLAT TUBES

2024, 55(9):  62-69. 

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In order to investigate the characteristics of falling film flow on the shell side of a special-shaped tube-wound heat exchanger, a three-dimensional physical model of the tube-wound heat exchanger was established, the multi-phase flow model based on the volume of fluid (VOF) method was numerically simulated, and the characteristics of falling film flow outside the tube of circular tube and flat tube were compared and analyzed. The results showed that the axial distribution of the falling film flow outside of the round tube and the flat tube showed the shape of "trough-peak-trough", and the falling film flow velocity of the flat tube was obviously higher than that of the round tube. The thinnest part of the outer liquid film of the round tube was at 120° of the circumferential angle of the round tube, and the thinnest part of the outer liquid film of the flat tube was at 90°- 120°. With the increase of pipe spacing, the average liquid film thickness of the round tube and the flat tube showed a downward trend, and the circumferential average film thickness of the flat tube was 10%-29% thinner than that of the circumferential average film thickness of the equal circumference of the round tube. With the increase of the winding angle, the circumferential average film thickness of the flat tube was 4%-28% thinner than that of the circumferential average film thickness of the circumferential round tube. Therefore, it is recommended to use the flat tube instead of the round tube as the winding tube of the winding tube of the tubular heat exchanger.

PRACTICE OF INCREASING HEAVY NAPHTHA PRUDUCTION IN 4.0 Mt/a HYDROCRACKING UNIT

2024, 55(9):  70-77. 

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In order to increase the production of high quality continuous reforming feedstock, the No.1 4.0 Mt/a hydrocracking unit of Zhejiang Petrochemical Co., Ltd. was revamped and the original catalyst was replaced with chemical type hydrocracking catalyst RHC-220. After changing agent, the radial temperature difference at the bottom of each bed was controlled within 3 ℃, the yield of heavy naphtha increased from 29.29% to 42.73%, and the BMCI of unconverted oil decreased from 15 to 5.5. It can adapt to the working condition of the hydrogenated gas oil in slurry bed, enrich the raw material composition of the unit, ensure the high load operation of the unit, and optimize the product structure and quality of the unit. It provides strong support for the increasing production of PX with high added value.

INDUSTRIAL PRACTICE OF BLENDING HEAVY AROMATIC OIL INTO COKER GASOLINE/DIESEL HYDROGENATION UNIT

2024, 55(9):  78-83. 

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The catalytic diesel and C10+ heavy aromatics produced by a petrochemical enterprise have a large output and poor properties. In order to solve the problem of difficult processing of heavy aromatics oil, some FCC diesel and C₁₀+ heavy aromatics were modified to the coker gasoline/diesel hydrogenation unit for processing. Industrial experiments were conducted on blending heavy aromatics oil at different ratios, and the changes of raw material propertyies, main operating parameters, product properties, material balance and other data under different operating conditions were compared and analyzed. The results showed that when the inlet hydrogen partial pressure was 7.0 MPa and inlet hydrogen/oil volume ratio was 530-580, after blending about 8% heavy aromatic oil, the diesel blending component with a sulfur mass fraction of 7.3 μg/g, a cetane number of 49.2 and a polycyclic aromatic hydrocarbon content of 6% was obtained. Under the conditions of low pressure and low hydrogen/oil ratio, the saturation of aromatics can reach equilibrium at low reaction temperature, and the amount of heavy aromatics can be adjusted according to the equilibrium conversion rate.

OPTIMIZATION AND LONG-TERM OPERATION OF HYDRO-UPGRADING UNIT FOR PROCESSING NAPHTHENIC FEEDSTOCK

2024, 55(9):  84-92. 

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In order to improve the economic benefits of the whole plant, according to the type of catalyst filled in the 1.2 Mt/a hydro-upgrading unit and the reaction mechanism of cycloalkyl diesel processing, the composition of the crude oil in the whole plant was optimized to achieve long-term stable operation. By adjusting the operating conditions of the unit, optimizing the crude oil processing ratio, and adding filtration facilities, the flexible switching of the unit under different production conditions was realized. The optimized results indicated that, on the basis of the loaded high diesel selectivity catalyst, it could flexibly switch 3 working conditions, such as producing No.2 fuel oil, national VI vehicle diesel and providing raw materials for downstream precision fractionation units, while keeping maximum diesel yield. The long-term operation results of the unit showed that the deactivation rate of hydrofining catalyst was 0.28 ℃/month(a month was counted as 30 days), and that of hydroupgrading catalyst was 0.24 ℃/month, both of which were relatively low and had good operational stability.

COMMERCIAL APPLICATION OF INORGANIC MEMBRANE PURIFICATION TECHNOLOGY FOR COKER GAS OIL

2024, 55(9):  93-97. 

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The successful application of inorganic membrane purification technology for coker gas oil (CGO) in the 0.3 Mt/a CGO purification unit of SINOPEC Jinling branch was introduced, including the structure of the inorganic membrane, purification principle and process flow of the unit. The results of industrial application showed that the inorganic membrane purification unit for coker gas oil had the advantages of simple operation, stable operation, strong anti-pollution ability and good purification effect. After purification, the mechanical impurity content in CGO was always less than 0.01% with a removal rate more than 92%,and a purified CGO yiela above 90%, which could meet the feeding requirements of the following process.After 115d of operation,the transmembrane pressure difference increased from initial 83.95kPa to 103.00kPa,showing a good operation stability.

RESEARCH ON COKING AND SCALING IN THE SPIRAL WOUND INLET AND OUTLET HEAT EXCHANGER OF REFORMING UNIT

2024, 55(9):  98-106. 

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The physical characteristics and composition of coking and scaling samples in different parts of the spiral wound inlet and outlet heat exchanger in catalytic reforming unit were investigated through experimental and analysis. Furthermore, the main causes of coking and scaling in the heat exchanger were analyzed. The results showed that the coking and scaling samples in the lower header and tube side were mainly composed of hydrocarbons, while the coking and scaling samples in the shell side were mainly composed of catalyst dust. There are certain amounts of ammonium salts in the coking and scaling samples in different parts. The hydrocarbons for coking and scaling in the lower header are mainly heavy oil, while the heavy oil content for coking and scaling in the tube side and shell side is relatively low and the degree of carbonization is high. The molecular weight and aromatic ring number of coking and scaling samples in the lower header, tube side and shell side increase sequentially. To inhibit coking and scaling in spiral wound inlet heat exchanger, the formation of coking and scaling in the lower header should be controlled. The cleaning of spiral wound inlet and outlet heat exchanger should adopt the combination method of mechanical coke removal and chemical cleaning, and ammonium salt corrosion should be prevented during the cleaning process.

ANALYSIS AND SUGGESTION ON INTERNAL LEAKAGE OF HIGH-PRESSURE HEAT EXCHANGER IN RESIDUE HYDROTREATING UNIT

2024, 55(9):  107-111. 

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During the operation of the residue hydrotreating unit, it was found that the sulfur content of the hot low-pressure separator oil increased abnormally and the quality of the hydrotreated residue was unqualified. Based on impurity removal rate analysis, heat analysis of heating furnace and FT-ICR MS analysis, it was determined that there was internal leakage in the high-pressure heat exchanger, and the estimated leak at the end of the run was close to 15%. After the shutdown, a water pressure test was conducted on the heat exchanger, and it was judged that the cause of the leakage was due to the small pre-tightening force of the top pressure bolt. In the early stage of operation, the pressure drop of the reactor was relatively small, and the heat exchanger operated normally. As the operating time increased, the pressure drop between the tube side and the shell side increased, the pressure on the shell side exceeded the rebound force of the metal coating pad, and the leakage occurs at the sealing point between the tube side and the shell side of the heat exchanger. The feed oil with high impurity content directly leaked into the hydrotreated product, resulting in the increasing impurity content of the product. It is suggested that the structure of metal toothed gasket and steel ring should be used to replace the metal cover cushion, and the pre-tightening force of heat exchanger should be re-calculated to ensure long-term efficient operation of the high-pressure heat exchanger.

COMPARISON OF CHLORINE CONTENT IN GASOLINE TESTED BY INTER-LABORATORY

2024, 55(9):  112-117. 

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A comparative study on the determination of chlorine in gasoline was carried out, and a total of 51 laboratories reported their testing results. The results of chlorine content were analyzed by frequency distribution statistics and robust Z-ratio statistics. The results showed that there was little difference between the arithmetic mean and the median value of each sample, and the distribution of results was symmetrical. The frequency distributions of the results were approximately normal. Two methods were used in the comparative study: X-ray fluorescence spectrometry and oxidative microcoulometry. There was no significant difference between the arithmetic means of the two methods. X-ray fluorescence spectrometry has the characteristics of simple operation, fast analysis speed, high precision and good stability, and the deviation of the results was smaller than that of oxidative microcoulometry in this comparative study. The overall satisfaction rate of Z-score evaluation was 88.2%, which indicated that the detection level of related laboratories was high and could provide reliable support for the detection of chlorine content in petroleum products.

GREEN SUSTAINABILITY ANALYSIS OF SOIL THERMAL DESORPTION REMEDIATION TECHNOLOGY BASED ON LIFE CYCLE ASSESSMENT

2024, 55(9):  118-128. 

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Based on the whole life cycle assessment software eFootprint and five cases of ectopic thermal desorption remediation projects of contaminated soil in East China, the green sustainability of thermal desorption technology was evaluated from the perspective of environmental impact potential. The results showed that natural gas, activated carbon and electric power were the main environmental factors affecting the thermal desorption remediation technology, and the cumulative environmental impact frequencies were 95.00%, 97.03% and 92.82%, respectively. For primary energy consumption potential, climate change potential and ozone layer depletion potential, soil pretreatment was the main influence stage, contributing 51.37%, 59.09% and 53.86%, respectively. For water resources consumption potential and competition-land use potential, exhaust gas treatment is the main influence stage, accounting for 55.1% and 99.92%, respectively. During the pretreatment of contaminated soil, diesel oil had the greatest influence on the ozone layer depletion potential and competition-land use potential, accounting for 83.68% and 100%, respectively. In the main treatment process, natural gas is the main contributing factor for all sustainability and green indicators, and the contribution rate of all indicators is more than 60%. In the process of tail gas treatment, the contribution of wastewater to primary energy consumption potential, non-biomass resources consumption potential, climate change potential, acidification potential, eutrophication potential and inhalable inorganic potential was 75.90%, 66.92%, 81.90%, 91.98%, 93.61% and 90.76%, respectively. Taking into account the impact of each stage, electric heating or other clean energy sources can be used instead of traditional diesel heating, and research and promotion of recycled or biodegradable polyvinylidene fluoride membrane materials can be carried out, developing and using low or calcium-free soil amendment to reduce the need for quick lime, and gradually increasing the proportion of renewable energy used in the thermal desorption process to improve energy and remediation efficiency and reduce environmental emissions, therefore, the green sustainability of thermal desorption technology can be improved.

RESEARCH ON THE APPLICATION OF HYDROGEN RECOVERY FROM REFINERY EXHAUST GAS

2024, 55(9):  129-135. 

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In view of the configuration of hydrogen purification system and the properties of exhaust gas of a newly built 20 Mt/a refinery of an enterprise, the scheme of process optimization based on the original hydrogen recovery process was determined. The implementation effect of the optimization scheme was verified by detailed material flow, hydrogen production, exhaust emissions to the fuel gas network, compressor handling capacity, membrane separation module handling capacity, and benefit and investment accounting. The results showed that the recovery of the hydrogen from the desorption gas of No.5 PSA(pressure swing adsorption) unit by membrane separation and PSA coupling process increased 9 880.53 m³/h, and the annual economic benefit of the refinery was about 25.498 6 million Yuan. However, the scheme of building a new hydrogen PSA unit can increase hydrogen production by 14 351 m³/h, but the new PSA cannot be centrally arranged in the hydrogen purification area because of its large footprint, as a result, the timeliness of operation and accident treatment is reduced.

ANALYSIS OF ENERGY CONSUMPTION AND ECONOMY OF HYDROGEN PRODUCTION FROM METHANOL STEAM REFORMING

2024, 55(9):  136-143. 

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Based on the processing parameters of industrial hydrogen production from methanol, a process model of hydrogen production from methanol steam reforming was established by using Aspen Plus software. The reaction thermodynamics of methanol steam reforming was discussed, and the effects of various parameters on energy consumption, material consumption, hydrogen cost, and CO₂ emission intensity in the hydrogen production process were analyzed. The results showed that the conversion of methanol increased with the increase of reaction temperature, but the CO selectivity increased and the hydrogen yield decreased. Under the optimum conditions of a temperature of 240 ℃,a pressure of 1.5 MPa, a molar ratio of water to alcohol of 1.8, and a PSA unit H₂ yield of 90%, the methanol consumption, comprehensive energy consumption, CO₂ emission intensity and hydrogen cost of the process were 5.96 kg/kg, 1 185.98 kgOE/t(1kgEO=41.8MJ), 10.45 kg/kg and 17.46 Yuan/kg, respectively. Higher reaction pressure and PSA unit H₂ yield, lower molar ratio of water to alcohol and reaction temperature were beneficial to energy saving and CO₂ emission reduction in the process of methanol hydrogen production. The order of influence on hydrogen production by steam reforming of methanol decreases as follows: H2 yield of PSA unit > molar ratio of water to alcohol > the reaction pressure > the reaction temperature.

APPLICATION OF ASPEN PLUS FOR REDUCING THE OPERATING PRESSURE OF DE-BUTANE COLUMN

国金 黄

2024, 55(9):  144-149. 

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The scaling problem of polymer in the de-butane column is one of the main factors that restrict the long-term operation of ethylene plants. Recently, the newly-built unit has achieved significant results in preventing polymer scaling in the de-butane column by reducing the operating pressure. Taking the de-butane column as an example, the feasibility, economy and risk points of the step-down process were analyzed and summarized, the process parameters after step-down operation were simulated and optimized by using the chemical process simulation software Aspen Plus, and the optimization results were applied to the actual production process. The results showed that the depressurisation limit of the de-butane column was 350 kPa, the temperature of the whole column decreased about 4 ℃ after depressurisation, the C₄ mole fraction of the crude cracked gasoline in the column kettle decreased by 0.32 percentage point, the low pressure steam was saved by 1.3 t/h, and the energy consumption and the loss of the C₄ product of the plant were reduced. The pressure drop of the circulating water side, the flow rate of the circulating water in the heat exchanger and the temperature difference of the logarithmic heat transfer were all within a reasonable range.

DEVELOPMENT OF ETHYLBENZENE DEHYDROGENATION REACTOR MODULE BASED ON CAPE-OPEN STANDARD AND WHOLE PROCESS SIMULATION

2024, 55(9):  150-157. 

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Based on the fact that the conversion rate of ethylbenzene dehydrogenation unit is lower than design value under vacuum insulation, the chemical kinetic model for adiabatic dehydrogenation of ethylbenzene to styrene including the small molecule steam conversion reactions and a reactor model were established. The kinetic parameters of the model were estimated with the data from an industrial ethylbenzene dehydrogenation unit and their reliability was verified. A reactor module of ethylbenzene dehydrogenation to styrene was developed by C++ language and COM technologies according to the CAPE-OPEN standards, and the whole process model of ethylbenzene dehydrogenation to styrene was built on Aspen Plus platform. The simulation results of the reactor and distillation column were in good agreement with actual situation. The influence of the process parameters on the conversion during the operation mid-term of the unit was further investigated, and the suitable process parameters were put forward. It can provide useful support for the process design and production optimization of ethylbenzene dehydrogenation to styrene.

PROGRESS AND REFLECTION ON THE LONG-TERM OPERATION TECHNOLOGY OF THE FIXED-BED RESIDUE HYDROTREATING UNIT

2024, 55(9):  158-170. 

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In response to the technical requirements for the long-term operation of a fixed-bed residue hydrotreating unit, the key factors restricting its operation period and improvement direction were analyzed first, and then the advantages and disadvantages of the existing fixed-bed residue hydrotreating guard reactor technology were compared. Finally, the future development direction of long-term operation technology was discussed. It is considered that the deactivation caused by metal deposition and carbon deposition is the main factor that restrict the operating cycle of the fixed-bed residue hydrotreating unit; the cut-off guard reactor technology and up-flow guard reactor technology are more suitable for solving the problem of increasing pressure drop of the reactor, which can prolong the running period of the unit; the rotary guard reactor technology and catalyst on-line displacement guard reactor technology can significantly extend the operating cycle of unit, but there are problems of complex process, high investment and high technical safety risks. The technology of gradually cut-off guard reactor has the advantages of both simple process and significantly extended operating cycle, and the development of new guard reactor technologies with more simplified processes is emphasized in the future. At the same time, attention should be paid to the development of high-capacity metal catalyst grading technology, catalyst coke reduction technology, and low-pressure and high-efficiency residual oil hydrogenation catalyst.

RESEARCH PROGRESS AND EXPERIMENTAL EXPLORATION OF SUSTAINABLE AVIATION FUEL PRODUCTION TECHNOLOGY

2024, 55(9):  171-176. 

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China's aviation industry is growing at the fastest rate in the world, but also facing increasingly stringent international emission reduction requirements. As the most effective aviation emission reduction measures,sustainable aviation fuel has broad development prospects and market needs. In recent years, the production of sustainable aviation fuel from biomasshas been regarded as apromising non-oil route for the production of alternative aviation fuels.The most technical and economic advantages lie in the hydrogenation of animal and vegetable oil and biomass gasification for the production of sustainable aviation fuel. However,factors such as feedstock availability, price fluctuations and high processing costs affect the availability and economic benefits of sustainable aviation fuel. The technology of producing sustainable aviation fuel from renewable energy sources has the advantages of unlimited resource supply, high efficiency of chemical reaction process and easy realization of large-scale industrial production, which is the most fundamental solution to the problem of sustainable aviation fuel supply.

METALLOCENE CATALYSTS AND THEIR SUPPORTS FOR OLEFIN POLYMERIZATION

2024, 55(9):  177-186. 

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Metallocene catalysts have attracted attention from both academic and business communities due to the single center catalytic performance in the polymerization of α-olefins, dienes and styrene. In order to further improve the activity and utilization efficiency of catalysts, prevent the occurrence of kettle sticking phenomenon and effectively control the microstructure of catalytic products, metallocene catalysts are usually loaded on the carrier for use. The basic structure and development history of metallocene catalysts were introduced, and the kinds of supports for metallocene catalysts were summarized, including MgCl₂, molecular sieves or porous materials, layered materials, polymers, carbon nanotubes and graphite, and silica gel, and self-loading characteristics and properties were summarized. It was pointed out that it was still an important work to search for highly active catalysts and their efficient loading processes in this field in the future.