Table of Content

12 August 2022, Volume 53 Issue 8

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DEVELOPMENT AND INDUSTRIAL PRACTICE OF HEAVY OIL CATALYTIC CRACKING PROCESS OVER MESOPOROUS ZEOLITE FOR LOW COKING LOW ENERGY CONSUMPTION AND HIGH OLEFIN YIELD

2022, 53(8):  1-10. 

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Based on the innovations of both catalytic materials and reaction engineering of diameter-transformed fluidized bed reactor, the highly selective catalytic cracking process from heavy hydrocarbon to olefins was proposed, and industrial test was carried out, which was aimed at the improvement of the yield and the selectivity of light olefin products. The industrial results were consistent with those of laboratory results, and the selectivity of olefin products was greatly improved. The successful industrialization proved the feasibility and effectiveness of the diameter-transformed fluidized catalytic cracking technology by using mesoporous zeolites catalyst, which could provide technical support for the smooth transformation from oil refining to chemicals. At the same time, it lays a reliable theoretical foundation and accumulates rich industrial practice for the in-depth development of targeted catalytic cracking.

DEVELOPMENT OF RESIDUUM HIGH-SELECTIVITY CATALYTIC CRACKING （RTC-G）TECHNOLOGY

2022, 53(8):  11-15. 

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In order to produce more gasoline and light olefins from the catalytic cracking of inferior heavy oil，based on the concept of high catalyst concentration，pseudo uniform reaction temperature and pseudo constant gas phase velocity，a method which use a fast fluidized bed reactor has been proposed to crack inferior heavy oil. Research of catalytic cracking reaction in a fast fluidized bed reactor had been carried out by using the feed of No.2 FCC unit of SINOPEC Jinan Company，from which the residuum high-selectivity catalytic cracking technology（RTC-G）had been formed. The research indicated that in comparison with the riser reactor，the yield of LPG and gasoline is 2.33 percentage points and 0.35 percentage point higher，the yield of dry gas is 0.34percentage point lower by using the fast fluidized bed reactor. Meanwhile，both product conversion and selectivity of high-valued product have competitive advantages. The yield of LPG and propylene from inferior heavy oil could respectively reach 25.52% and 11.84% when appropriate catalyst is used.

APPLICATION AND PROSPECT OF MEASURES TO REDUCE DIESEL FUEL IN OIL REFINING ENTERPRISES

2022, 53(8):  16-20. 

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In recent years, with fierce competition in the domestic oil market and intensified changes in the consumption structure, oil refining enterprises need to constantly optimize their product structure, vigorously reduce the production of diesel, and increase the production of gasoline, jet fuel and ethylene raw materials as needed, and this is the primary task to enhance the competitiveness of enterprises at present and in the long term in the future. Combined with the actual situation of SINOPEC Changling Company, through the adoption of a series of new technologies and optimization measures, good results have been achieved in changing the yield of oil products and optimizing the structure of oil products. Based on the actual case of the enterprise, combined with the experience of other refining and chemical enterprises in product structure adjustment in recent years, the development and application of new technologies, the suggestions were put forward for the adjustment of products structure under the goal of "double carbon" and 14th Five-Year Plan.

OPERATION ANALYSIS OF 2.6 Mt/a SINGLE SERIES FIXED-BED RESIDUE HYDROGENATION UNIT

2022, 53(8):  21-25. 

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The 2.6 Mt/a single-series fixed-bed residue hydrogenation unit in SINOPEC Luoyang Company is the largest single-series residue hydrogenation unit in China. During the first start-up and operation, the some problems such as high filter differential pressure, periodic pulsation of circulating hydrogen content, and sulfur-containing wastewater were appeared, which brought great difficulty to the stable operation of the plant. Through the analysis of raw material residue, process flow, equipment operation and other aspects, the above problems have been solved or alleviated successively, and the long-term operation of the device has been realized. According to the calibration results, the raw material properties and product quality were relatively stable, the desulfurization rate was 75.16%, the denitrification rate was 34.48%, the carbon residue removal rate was 46.02%, and the metal (Ni+V) removal rate was about 77%, which provided the high quality raw material for the downstream device.

STUDY ON PRODUCTION OF LOW-SULFUR HEAVY MARINE FUEL OIL BY VISBREAKING PROCESS

2022, 53(8):  26-30. 

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With the increasing prominent contradiction between domestic refining capacity and oil products demand, the production of low-sulfur marine fuel has become the key to heavy oil balance and profitability. At present, light fractions are often used to dilute low-sulfur vacuum residue to produce low-sulfur marine fuel. The viscosity and pour point of vacuum residue can be greatly reduced by visbreaking process, and blending of vacuum residue to produce low-sulfur marine fuel can be realized. The shows that the viscosity reduction rate of residual oil is over 90% and the pour point is below 30℃. Compared with the original blending scheme, the blending amount of light fraction is reduced from 30% to 3.2%, and the production cost is greatly reduced. In addition, the production of low-sulfur marine fuel by a visbreaking route can reduce the load of the hydrogenation unit, the amount of high carbon residue and low quality components entering the FCC unit, and improves the feed to the catalytic unit. The comprehensive calculation of enterprise benefit can increase by 79.82 million Yuan/a. The production of low-sulfur heavy marine fuel from low-sulfur residue by visbreaking process provides a reference for the production of low-sulfur marine fuel and the efficient utilization of low-sulfur residue.

STUDY ON MEASURES TO REDUCE ASH CONTENT IN PETROLEUM COKE

2022, 53(8):  31-34. 

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According to the characteristics and application fields of high ash petroleum coke, the measures to reduce ash content in petroleum coke were studied. The results showed that the main elements in the ash of petroleum coke were O, Ca, S, Fe, Ni, Si, Mn and so on. The total contribution of metal and non-metal elements to the ash of petroleum coke was about 43% and 57%, respectively. The results of XRD analysis showed that under the condition of high calcium content in crude oil, most of the substances in petroleum coke ash existed in the form of metal oxide, especially the proportion of CaSO₄ and CaO which had stable structure was the highest, and the total proportion of the two calcium compounds in ash is about 90%. Decalcification of high calcium crude oil can obviously reduce the ash content of delayed coking coke and the proportion of CaSO₄ and CaO in the ash. The result showed that there was a linear relationship between the ash content of petroleum coke and the calcium content of crude oil. This conclusion can provide a certain reference for the production and sale of petroleum coke.

FIRST REGENERATION AND APPLICATION OF SR-1000 REFORMING CATALYST IN KAZAKHSTAN REFINERY

2022, 53(8):  35-40. 

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The SR-1000 catalyst developed by SINOPEC Research Institute of Petroleum Processing was regenerated for the first time in the 1.0 Mt/a semi-regenerative reforming unit of PKOP Refinery in Shimkent, Kazakhstan. Compared with the fresh catalyst, the reduction of specific surface area and pore volume of the coking catalyst was less than 2.0%, which showed that the coking process control was relatively stable and the hydrothermal stability of the catalyst was good. Compared with the fresh catalyst, the preliminary results of SR-1000 regenerated catalyst showed that at the condition of the reforming feed of the SR-1000 regeneration catalyst being higher by 17.1 m³/h，the sum of the cyclic alkane and aromatics mass fraction was increased by 6.01 percentage points than that of the fresh catalyst，the stable gasoline RON with regenerated catalyst was higher than that with fresh catalyst by 0.5 , and liquid yield was increased by 0.9 percentage point than that of the fresh catalyst, which showed that the regenerated SR-1000 catalyst had good performance.

COMMERCIAL APPLICATION OF NEW V-TRAP CATALYTIC CRACKING CATALYST IN MIP UNITS

2022, 53(8):  41-47. 

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New vanadium-trap（V-trap） catalytic cracking(FCC) catalysts that could be used in complete regenerated units were developed by using means of catalyst particles surface coating technology. The results show that the catalyst has better ability of metal tolerance and high bottoms conversion. The catalyst has been applied commercially in the third FCC unit of SINOPEC Jinling Company. The results of routine statistic data showed that the catalyst had good ability of vanadium resistance and excellent catalytic performance when the mass fraction of vanadium in the equilibrium catalyst exceeds 6 000 ug/g. Under the condition of reducing the catalyst consumption, the activity of the balancing agent was still increased more than 3, and showed excellent activity stability. The yield of LPG and gasoline was increased by 3.54 percentage points, the yield of LCO was decreased by 1.67 percentage points, the yield of propylene was increased by 0.69 percentage point, and the volume ratio of H₂ and CH₄ was obviously decreased by 0.23 percentage point.

START-UP AND APPLICATION OF THE EX-SITU TRULY SULFIDED HYDROTREATING CATALYSTS IN HYDROGENATION UNIT

2022, 53(8):  48-53. 

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The application of ex-situ truly sulfided hydrotreating catalysts in 1.7 Mt/a naphtha hydrofining, 0.6 Mt/a kerosene hydrofining, 2.2 Mt/a liquid-phase diesel hydrofining and 0.8 Mt/a hydrocracking was introduced. The start-up process of the truly sulfided catalyst can not only avoids the use of sulfiding agent and does not produce waste gas containing hydrogen sulfide and acidic sewage，but also greatly reduces the start-up time. From the beginning of oil feeding to the production of qualified products, the time for naphtha hydrogenation and jet fuel hydrogenation was 21.5 h and 15 h, respectively. The time saving effect of liquid-phase diesel hydrogenation unit was the most obvious, from 130 h to 27 h. It took 14 h from the inlet to the outlet temperature of 300 ℃, which saves more than 30 h compared with the start-up time of the oxidized catalyst.

ENLIGHTENMENT OF IMPURITY DISTRIBUTION OF SPENT RESIDUE HYDROTREATING CATALYST ON OPTIMIZATION OF CATALYST GRADATION

2022, 53(8):  54-61. 

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The spent catalysts in the two cycles before and after the revamping of the residue hydrogenation unit of Hainan Refining & Chemical Co. Ltd. were analyzed. The results showed that along the reaction flow direction, the deposition amount of (nickel + vanadium) was increased first and then was decreased, and the deposition proportion of vanadium was higher in the upstream of the reaction flow direction; the amount of iron deposition showed a trend of high front and then low, and there was a phenomenon of capping; the carbon deposition amount was gradually decreased, and the high temperature operation led to a significant increase in the amount of carbon deposition on the catalyst. According to the different characteristics of impurity deposition distribution and its influencing factors, the improvement directions of residue hydrogenation catalyst gradation were proposed.

COMMERCIAL APPLICATION OF HIGH-DENSITY CATALYST PS-Ⅷ FOR CONTINUOUS REFORMING

2022, 53(8):  62-67. 

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In view of the demand for capacity expansion of continuous reforming units in some refineries, high-density catalyst provides a new technological solution for capacity expansion of existing units.The industrial test of domestic continuous reforming high-density catalyst PS-Ⅷ was carried out in SINOPEC Jiujiang Company.The industrial test results showed that under the operations of a fresh feed rate of 163.3 t/h, a WAIT of 519 ℃,a molar ratio of hydrogen to oil of 2.24 and a WHSV of 1.46 h^-1, the yield of C₅+ products was 88.4%, the RON of C₅+ products was 101.8, the yield of aromatics was 69.7%, and the yield of hydrogen was 3.85%. The consumption of catalyst was low, and coke deposition rate was equivalent to normal density catalyst. Under the operations of the same RON, the reaction temperature of PS -Ⅷ was 4 ℃ lower than that of PS -Ⅵ. Meanwhile, compared with PS -Ⅵ, the hydrogen yield, C₅+ product yield and aromatics yield of PS-Ⅷ were increased by 7.8 m³/t, 0.5 percentage point and 0.4 percentage point respectively, and the yield of LPG was reduced by 0.3 percentage point. PS-Ⅷ catalyst showed excellent reaction activity and stability when the content of light components in fresh feed rate was high and (naphthene+aromatics) content was lower than the designed value. The successful commercial application of high-density catalyst PS-Ⅷ is of great significance to the serialization of domestic continuous reforming catalyst.

THERMODYNAMIC ANALYSIS AND EXPERIMENTAL STUDY ON THE ISOMERIZATION OF n-BUTANE TO ISOBUTANE

Yu ZhongWei Zhang Qiuping Wang Jieguang Ma Aizeng Ling-jiang Kong

2022, 53(8):  68-72. 

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Based on the analysis of the reaction characteristic and thermodynamic behaviors of n-butane isomerization to isobutane, standard molar enthalpy change, standard molar Gibbs free energy change, standard equilibrium constant and equilibrium conversion of n-butane at different temperatures were obtained, and the n-butane isomerization over Pt/Al₂O₃-Cl catalyst was investigated. The results show that the isomerization of n-butane is an exothermic reaction, and the equilibrium conversion of n-butane can be increased by lowering the reaction temperature. In the n-butane isomerization catalyzed by Pt/Al₂O₃-Cl, the reaction temperature, reaction pressure, space velocity of n-butane and molar ratio of hydrogen to hydrocarbon (H₂/HC) have obvious effects on the conversion of n-butane. The n-butane conversion can be increased by selecting reaction temperature and pressure carefully and decreasing n-butane space velocity and H₂/HC molar ratio properly. Under optimum reaction conditions, the conversion of n-butane was in good agreement with that of thermodynamic equilibrium, which proved the reliability of thermodynamic analysis.

COMPUTATIONAL FLUID DYNAMICS SIMULATION OF GAS-SOLID DOWNER DISTRIBUTOR

2022, 53(8):  73-78. 

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In order to solve the problem that it is difficult to take into account both high solids holdup and uniform gas-solid distribution in the inlet distributor of the downer, a novel gas-solid distributor for particle concentration in downers was proposed based on the mechanism of gas-solid two-phase flow in downer. The performance of downer fluid mechanics was investigated by using the developed structural drag model coupled with computational fluid dynamics software. The simulation results showed that the simulation results of the structural drag model were consistent with the experimental data. Compared with the distributor in the literature, the novel distributor is more uniform with the design of subarea fluidization, Venturi type overflow pipe and funnel type. When the solids circulation rate was up to 700 kg/(m².s), the overall solids holdup could reach 0.06 with uniform gas-solid distribution. Furthermore, the solid circulation rate plays a more sensitive role in increasing solids holdup than the gas velocity.

PERFORMANCE SIMULATION OF OVERFLOW GAS-LIQUID DISTRIBUTOR IN FIXED-BED REACTOR

2022, 53(8):  79-83. 

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As an important component in fixed-bed reactor, the performance of gas-liquid distributor directly affects the operation efficiency of the reactor. In this paper, using oil and hydrogen as raw materials, Euler-Euler multiphase flow model and standard k-εturbulence model, a mathematical model of distributor in fixed bed reactor was established by using computational fluid dynamics software. On the basis of verifying the accuracy of the model, the performance of the distributor composed of overflow distributor was analyzed, and the effects of the arrangement, spacing and height of the distributor on the performance of the distributor were investigated. The results showed that the distribution of the liquid phase in the gas-liquid distribution tray was the smallest, only 1.86%, when arranged in square form, the spacing between the distribution points was 118 mm and the spacing between the distributor and the catalyst bed was 150 mm. Compared with the basic configuration of the distribution plate, the liquid distribution uniformity was reduced by 42.9%.

HETEROATOM COMPOSITION OF COKE DEPOSITED ON CATALYTIC CRACKING CATALYST AND ITS REGENERATION CONVERSION MECHANISM

2022, 53(8):  84-90. 

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Heteroatom composition of coke deposited on catalytic cracking catalyst and flue gas were analyzed under different process conditions. According to density functional theory, the most stable configurations of typical nitrogen and sulfur compounds in carbon deposits were obtained by using Gaussian 09 software at B3LYP/def2-TZVP level, the Laplacian bond level was used as the criterion, and the conversion mechanism of heteroatom in carbon deposits was studied. The results showed that the nitrogen-containing compounds in coke deposited on catalyst were mainly pyridine, pyrrole and quaternary ammonium compounds, and the sulfur-containing compounds were mainly thiophene compounds. In the initial stage of catalyst regeneration, nitrogen-containing compounds escaped in the form of :NH and .CN were mainly converted into NH₃ and HCN, sulfur-containing compounds escaped in the form of .HS and :S were mainly converted into H₂S and COS, and NH₃, HCN, H₂S and COS were finally converted into NO_x and SO_x respectively. The simulation results were consistent with the flue gas composition under different regeneration process conditions.

MODELING THE DENITRIFICATION MECHANISM OF SELECTIVE CATALYTIC REDUCTION IN CATALYTIC CRACKING UNIT BASED ON INDUSTRIAL DATA

2022, 53(8):  91-96. 

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Based on the mechanism of selective catalytic reduction (SCR) technology, a set of denitrification mechanism modeling equations of regenerator flue gas SCR system in fluidcatalytic cracking unitwere established. According to a large amount data of SCR system, the mechanism model equations were solved by Runge-Kutta-Gill method, and the model parameters were optimized by combining genetic algorithm. The verification results show that the mean absolute percentage error of the model is 5.75% and the coefficient of determination is 0.906, which indicate that the established SCR denitrification mechanism model has strong generalization ability and high simulation accuracy. The model will be expected to play an important role in optimizing the operating conditions of the SCR systems for achievement standard ofnitrogen oxides emission of the treated flue gas.

STUDY ON PROCESS SIMULATION AND OPTIMIZATION OF HYDROCRACKING TAIL GAS DESULFURIZATION AND SOLVENT REGENERATION UNIT

2022, 53(8):  97-102. 

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Taking the hydrocracking tail gas desulfurization and solvent regeneration unit of a petrochemical company as the research object, based on the design data, the process simulation was carried out by using Aspen Plus process simulation software, and the process model was established, including absorption system and separation system. The simulation results are compared with the design data, and the error is within a reasonable range, which shows that the established model can better reflect the actual production situation of the unit and can be used in the subsequent analysis and optimization work. The influence of temperature, pressure, methyldiethanolamine concentration, steam load and other factors on the product distribution and quality of the unit are analyzed by using the established model. On this basis, the parameters were optimized to achieve the objectives of increasing efficiency, saving energy and reducing consumption. It has the guiding significance for the operation of the actual unit.

SIMULATION AND OPTIMIZATION OF MTBE CRACKING TO PRODUCE HIGH PURITY ISOBUTENE BASED ON ASPEN PLUS

2022, 53(8):  103-109. 

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Taking a MTBE cracking unit for producing high-purity isobutene as the research object, a steady-state model of the whole process of the unit was built by using Aspen Plus software. On this basis, using the sensitivity analysis tool, and on the premise of satisfying the product quality requirements, the paper optimized and analyzed important operating parameters of the distillation column pressure and reflux ratio at the top of the column in order to reduce the energy consumption of the unit. The results showed that the total load of the column bottom reboilers was reduced by 1 347 kW, the steam consumption of the column bottom reboilers was reduced by 2.12 t/h after the implementation of the optimization scheme, and the annual economic benefit was about 2.544 million Yuan.

APPLICATION OF DYNAMIC SIMULATION TECHNOLOGY IN ADVANCED PROCESS CONTROL PROJECT OF GAS FRACTIONATOR

2022, 53(8):  110-115. 

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An advanced process control (APC) project of multi-variable model predictive control was proposed to solve the problems of multi-disturbance, serious coupling and low automation in gas fractionator. During the execution of the project, it was difficult to obtain a reliable model for routine step test because of the long steady time caused by the large number of column plates and the long interval time of analyzer, and the product purity requirement was high, the step test would have great interference to the operation of the unit. In this paper, a dynamic model was built by Aspen Hysys dynamic software, and the step response curve of the dynamic model was used to build the predictive control model of APC project. The results show that the dynamic model has a good effect, greatly reduces the difficulty of step test, reduces the interference to the unit, and obtains a better control effect.

EFFECTS OF REGENERATION CONDITIONS ON DESULFURIZATION ACTIVITY OF SULFUR TRANSFER AGENT IN PARTIAL COMBUSTION REGENERATOR

2022, 53(8):  116-120. 

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In order to solve the problem of poor effect of sulfur transfer agent in a catalytic cracking unit with two-stage partial combustion regenerator, the influence of regeneration conditions on the desulfurization performance of sulfur transfer agent was investigated. The results show that the flue gas desulfurization (FGD) rate is increased by 4.54 percentage points when the temperature of the oxygen-poor regeneration unit is decreased by 10 ℃. With the increase of coke combustion air consumption, the content of CO in flue gas was gradually decreased. When CO volume fraction is decreased by 1.0 percentage point, the FGD rate can increase by 5.27 percentage points. When the total amount of main air remains unchanged, the FGD rate will increase by 0.65 percentage point with increasing the proportion of main air into the first regenerator by 1 percentage point. In addition, it was found that the change of catalyst inventory had little effect on the desulfurization effect of sulfur transfer agent.

SITUATION AND DEVELOPMENT TREND OF ULTRAVIOLET FLUORESCENCE STANDARD METHODS FOR DETERMINATION OF SULFUR CONTENT IN PETROLEUM PRODUCTS

2022, 53(8):  121-126. 

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The newly implemented Beijing local gasoline standard and the soon-to-be-implemented motor vehicle ethanol gasoline standard (GB 18351) have designated GB/T 34100 as the arbitration standard for the determination of sulfur content. At present, the domestic standards for the determination of sulfur content in light fuel oil by ultraviolet fluorescence method are GB/T 34100-12017 and SH/T 0689-12000, both of which adopt ASTM D5453, but the corresponding versions are different. In view of the doubts in the use of the national standard and the industry standard for the determination of sulfur content in oil products by ultraviolet fluorescence method, this paper expounded the development and changes of the standard for the determination of sulfur content by ultraviolet fluorescence method, and introduced the preparation, revision and development process of standard ASTM D5453. The differences between SH/T 0689, GB/T 34100 and ASTM D5453 were compared, and the shortcomings of the existing methods and the requirements for improvement were pointed out.