Table of Content

12 July 2021, Volume 52 Issue 7

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COMMERCIAL APPLICATION OF NOVEL DEEP CATALYTIC CRACKING TECHNOLOGY FOR RESID TO CHEMICALS（RTC）

2021, 52(7):  1-5. 

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Based on the analysis of DCC process unadaptable to inferior feedstock，a novel high efficient fast fluidized bed with special structure for heavy oil catalytic cracking was developed for production of propylene，and accordingly to form a process called RTC（Residue To Chemicals）. The old DCC unit in SINOPEC Anqing Company was revamped with the new RTC process by replacing the previous reactor of riser plus dense phase bed with the new developed fast fluidized bed reactor. Subsequently, the commercial application was completed. The commercial application results showed that in comparison with DCC，RTC not only showed excellent adaptability to inferior feed blended with hydrotreated residue，but also produced more propylene and ethylene with higher selectivity while coke and slurry yields decreased. In addition，the gasoline property was improved due to lower olefin content，higher aromatics and higher RON by applying RTC process.

STUDY OF HYDROGENATION PERFORMANCE OF RESIDUES WITH DIFFERENT HYDROCARBON STRUCTURES

2021, 52(7):  6-11. 

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The 1 500 h experiment of catalyst stability was conducted with residue of paraffin-base Qinghai crude oil (Qinghai residue) and residue of intermediate-base Saudi Arabia light crude oil (Saudi Arabia residue) as feedstock,respectively. The differences of the molecular structures of the feedstock and products were analyzed by Fourier transform ion cyclotron resonance mass spectrometer and NMR techniques，as well as the coke- composition of post-reaction catalyst in experiment （used catalyst）. According to the results in this study，Qinghai residue has high content of saturated hydrocarbon and long numerous side-chains on aromatic rings. The accessibility of Qinghai residue can be improved by cracking its side-chains with rapidly–rising temperature at the start of run. Besides，the tendency of coking is declined. The molecular of Saudi Arabia residue has high content of aromatics with short side-chains. It can achieve high removal rate of impurity at low temperature, but it tends to form coking-precursor when the temperature is high，which is one of the main factors causing deactivation of catalyst rapidly. Saudi Arabia residue has lager amount of coke-composition of used catalyst and high proportion of hard coke compared to Qinghai residue. The reaction temperature distribution of Qinghai residue hydrogenation was optimized. The temperature of the demetallization catalyst bed was increased rapidly，while the temperature of the desulfurization catalyst bed was decreased，forming the distribution of the high temperature down to low temperature. The data showed that the hydrogenated products with the optimized temperature had better properties.

RESEARCH AND INDUSTRIAL PRACTICE ON THE TREATMENT OF HIGH SILICON NAPHTHA IN FCC UNIT

2021, 52(7):  12-17. 

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In order to prevent the silicon in naphtha from harming the catalysts used in hydrogenation and reforming processes, a scheme of treating high silicon naphtha in fluidized catalytic cracking unit was proposed. High silicon naphtha was desiliconized in a pilot riser unit. By adjusting the blending ratio, reaction residence time and feedstock properties, the industrial process conditions were preliminarily determined, and the reaction mechanism was explored. The industrial experiment was carried out in a 2.80 Mt/a catalytic cracking unit of SINOPEC Tianjin Company, and the effect of this scheme on the desiliconization of naphtha was further verified. The results showed that when the high silicon naphtha was injected as terminator with the blending ratio less than 1% and the reaction residence time more than 3 s, the treatment effect was the best. The program has excellent desiliconization effect of naphtha and can avoid impurity pollution caused by using silicon catcher or desilication protector.

APPLICATION OF CATALYTIC OXIDATION METHOD IN DEEP DESULFURIZATION OF LIQUEFIED PETROLEUM GAS

2021, 52(7):  18-23. 

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The sulfur content of refined liquefied petroleum gas (LPG) often fails to meet the requirements of downstream users. Therefore, the study of high selective and deep desulfurization of LPG with H₂O₂ as oxidant under the specific catalyst was carried out. The most common residual sulfide in refined LPG was used to prepare model oil to explore the reaction conditions, and then the desulfurization test of refined C₄ was carried out under the best conditions. The results show that when C is the catalyst, the reaction temperature is 35℃, the molar ratio of n(H₂O₂)/n(S) is 4, and the concentration of H₂O₂ is 30%, the desulfurization rate of the simulated oil can reach more than 98%. Under the same conditions, the desulfurization rate of refined C₄ is only 50%, but after optimizing the mixing mode of H₂O₂, catalyst and refined C₄, it is found that the desulfurization rate of refined C₄ is close to 100%. In addition, the method has little effect on the hydrocarbon composition of hydrocarbon oil or refined C₄, indicating that this method has higher selectivity for oxidative removal of sulfide, and is expected to be used for ultra deep desulfurization of LPG in the future.

PREPARATION AND MECHANISM OF NEEDLE COKE FROM HIGH TEMPERATURE COAL TAR

2021, 52(7):  24-28. 

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Quinoline insoluble substance (QI) in high temperature coal tar is removed by solvent dilution and thermal filtration at 110 ℃, then the light components in solvent and coal tar are removed by vacuum distillation to obtain purified asphalt with moderate softening point and QI content of 0.548%. Furthermore, the content of QI in asphalt is reduced to 0.087% by mild hydrogenation process. Needle coke products are obtained by delayed coking at 500 ℃ and calcination at 1 000 ℃. Compared with a foreign product, the performance index is almost the same. The mechanism study shows that the catalytic hydrogenation of coal tar is a process of hydrogenation of unsaturated hydrocarbons, desulfurization and denitrification . After hydrogenation, the H/C atomic ratio of the system increases, and the contents of N and S elements decrease. In the further reaction, aromatics will undergo dehydrogenation, cyclization, aromatization and recombination to form polynuclear aromatic compounds with large molecular weight and thermodynamic stability, and then form planar disk-shaped condensed polynuclear aromatic compounds. Due to the space surface energy, the condensed polynuclear aromatic compounds will curl to form mesophase complex spheres, and then merge into parallel mesophase system, forming "needle like" junction under the action of air flow. Finally, the needle coke is obtained after solidification and coking.

INFLUENCE OF RESIN CONTENT ON HYDROTREATING PROCESS OF SHENGLI VACUUM RESIDUE

2021, 52(7):  29-33. 

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Shengli vacuum residue with different amount of resin as raw materials was hydrotreated in an autoclave. Elemental analysis, measurement of molecular weight , simulated distillation and content analysis of metal (Ni, V) were performed on oil samples before and after hydrotreating. The results showed that compared with the raw materials, the average relative molecular mass, the sulfur content, the nitrogen content and the metal content of hydrotreated liquid products of Shengli vacuum residue with different amount of resin decreased, while the H/C ratio increased. With the increase of resin amount, the average relative molecular mass, the H/C ratio of liquid products of hydrogenation increased, and the sulfur content decreased, while the content of nitrogen and metal decreased first and then increased. With the increase of resin amount, the yield of gasoline and gas, hydrogenation residue oil and coke reduced, while the yield of diesel and gas oil distillate increased.

EFFECT OF BLENDING FCC SLURRY ON DELAYED COKING UNIT

2021, 52(7):  34-37. 

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FCC slurry is blended in delayed coking unit. Compared with vacuum residuum，the FCC slurry has the characteristics of high density，low carbon residue，high aromatic content and high solid content. The experimental results of SINOPEC Jinling Company 1.6 Mt/a delayed coking unit showed that the yield of gasoline and diesel decreased，and the yield of gas oil and coke increased when the slurry blending ratio increased from 5.6% to 12.4%. The ash content of coke increased and the sulfur content of coke decreased simultaneously. Moreover，The increase of slurry blending ratio also led to the increase of fuel gas，steam and electricity consumption. The blending of slurry can cause coking in the furnace tube，blocking the filter at the bottom of fractionation tower and aggravating the wear of equipment. Controlling blending ratio，removing solid and adjusting the operation can be taken to ensure the stable operation of the delayed coking unit.

INDUSTRIAL TEST OF CONTINUOUS PREPARATION OF FCC CATALYST SLURRY GEL

2021, 52(7):  38-43. 

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A continuous preparation technology of FCC catalyst slurry gel was developed, and the industrial sideline test unit of continuous preparation/grinding was designed. The industrial test of continuous preparation of catalyst slurry gel with the capacity(dry basis) of 3 t/h and 6 t/h were carried out. The results show that the unit runs continuously and stably, and the feeding and discharging are smooth. Compared with intermittent technology of FCC catalyst slurry gel preparation, when the processing capacity(dry basis) was 3 t/h, both the two methods cost the same processing time, while the processing capacity(dry basis) was 6 t/h,the processing time was shortened by half and the power consumption were reduced by 56%-67%. The particle size of slurry gel prepared by continuous method was smaller,the catalyst prepared by continuous technology exhihited the lower average attrition resistence index by 0.6 percentage point, the higher micro-activity after aging at 100% steam for 17 h by 3.0 percentage points, showing the better hydrothermal stability.

APPLICATION OF ENHANCED SULFUR TRANSFER AGENT RFS09 IN CATALYTIC CRACKING UNIT

2021, 52(7):  44-48. 

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The application of sulfur transfer agent RFS09 in the 3.4 Mt/a MIP-CGP catalytic cracking unit of SINOPEC Zhenhai Refining & Chemical Company is introduced. It is shown that after the sulfur transfer agent RFS09 content reached 1.6% in the reactor and the regenerator, blue smoke was basically eliminated, SOx content in regeneration flue gas decreased by about 80%, the amount of alkali used for desulfurization decreased by 58%, and the annual cost reduction and efficiency increase reached 2.7 million Yuan. The utilization of sulfur transfer agent has no adverse effects on product distribution, circulation of catalyst between the reactor and the regenerator,and operation of the flue gas turbine.

ANALYSIS ON IMPURITY OF GUARD CATALYST FROM DIESEL HYDROCRACKING PROCESS

2021, 52(7):  49-55. 

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Guard catalysts of the diesel hydrocracking unit in a refinery were collected and characterized by X-ray diffraction (XRD), X-ray fluorescence spectrum (XRF), carbon-sulfur analysis, thermogravimetry-mass spectrometry analysis (TG-MS), N2 adsorption-desorption and scanning electron microscopy with energy dispersive X-ray (SEM-EDX) after toluene extraction treatment. The results showed that along the cross section of the guard catalyst, the non-metallic impurities Si and P were evenly distributed in the interior and exterior of the guard catalyst, and the impurities Ca and Fe were mainly deposited on the outer surface of the guard catalyst. A large amount of Si, P, Fe, Ca, C and other impurities deposited and formed a “shell” over the guard catalyst, which blocked the pore channel and covered the outer surface of the catalyst, resulting in a significant reduction in the ability of containing impurities. The falling off of the “shell” eventually leads to the increasing pressure drop in the reactor.

SYNTHESIS AND PERFORMANCE OF NEW ANTIOXIDANT 2-TERT-BUTYL-5-EPOXY PENTADECYL PHENOL

2021, 52(7):  56-60. 

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Based on the structural characteristics of cardanol, the molecular structure of environment-friendly antioxidant was designed. A new structure of phenolic antioxidant was synthesized by epoxidation and tert-butylation of cardanol. The structure of the synthesized antioxidant was characterized by F-T infrared spectroscopy and ¹³C-NMR spectroscopy, and its application in different base oils was investigated. The antioxidant properties and compatibility with amine antioxidants were studied. The results showed that the molecular structure of the synthesized phenolic antioxidant was 2-tert-butyl-5-epoxypentadecylphenol; in different types of lube base oils, especially in ester base oils, the synthesized antioxidant had good antioxidant performance. Besides, in dioctylsebacate, the synthesized antioxidant had good compatibility and synergistic effect with amine antioxidant, which was suitable for use as lubricating oil / grease additive.

EFFECT OF COMPLEX AGENT AND ANTIOXIDANT ON OXIDATION STABILITY OF COAL BASED GASOLINE ENGINE OIL

2021, 52(7):  61-65. 

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Taking coal based APIIII+ lube base oil from F-T synthesis as raw material, the initial oxidation temperature and high temperature deposit of the obtained formula oil were determined by high pressure differential scanning calorimeter (PDSC) and TEOST MHT-4 test device. The influences of complex agent and antioxidant on initial oxidation temperature and high temperature deposit of coal based base oil were studied. The results showed that the oxidation stability of base oil was not enhanced by the addition of complex agent and antioxidant. On the contrary, excessive antioxidant increased the formation of high temperature deposits due to its own oxidation. By testing the fully-formulated coal based gasoline engine oil, it could be seen that the initial oxidation temperature and the high temperature deposit were 259.94 ℃ and 18 mg, respectively. Compared with a certain brand of petroleum based 5W-30 gasoline engine oil, the coal based 5W-30 gasoline engine oil had better oxidation stability and lower high temperature deposit generation.

STUDY ON SYNERGISTIC EFFECT OF DIFFERENT ANTIOXIDANTS IN GREASE

2021, 52(7):  66-71. 

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The antioxidation of free radical terminating antioxidants and peroxide decomposing antioxidants in grease were investigated by differential scanning calorimetry，and the synergistic effect of the two antioxidants was studied. According to Arrhenius equation, the activation energy of the oxidation reaction of grease with different antioxidants was calculated. The results show that as free radical terminating antioxidants,the amines and phenolic antioxidants show synergistic effect which can improve antioxidant performance of grease. The ternary complex system of free radical terminating antioxidants of amines and phenols and peroxide decomposing antioxidants has good antioxidant synergistic effect, which can significantly improve the oxidation reaction activation energy of grease and greatly enhance its antioxidant performance.

APPLICATION OF LIQUID PHASE DECHLORINATING AGENT RDL-100 IN CONTINUOUS REFORMING UNIT

2021, 52(7):  72-75. 

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RDL-100 liquid phase dechlorinating agent developed by SINOPEC Research Institute of Petroleum Processing has been used in a 2.0 Mt/a continuous reforming unit of PetroChina Sichuan Petrochemical Company. The results of RDL-100 liquid phase dechlorinating agent running for 7 months showed that the dechlorinating agent had good dechlorination function, and the content of hydrogen chloride in reforming oil after dechlorination treatment was less than 1 μg/g. The dechlorinating agent is not hardened or sludded in the process of use, the pressure drop of dechlorination tank has no obvious change, and the service life is long, which can meet the requirement of dechlorination of reformate from continuous reforming unit, reduce the chlorine corrosion and salt formation of the depentanizer system, and ensure the stable operation of the unit for a long period.

TYPICAL CORROSION CASES AND PROTECTIVE MEASURES OF DELAYED COKER

2021, 52(7):  76-81. 

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Since the overhaul of the delayed coking unit in 2016, there have been corrosion on the top of the raw material buffer tank，the feed line on the coke tower，the shell of the reboiler at the bottom of the tower, and the cooler bundle at the top of the tower. The causes of corrosion were analyzed and protective measures were proposed. The short joint corrosion on the top of the raw material buffer tank is high temperature sulfur corrosion, which needs to adopt measures such as material upgrading or pipeline lining. The corrosion of the elbows of the feed line on the coke tower is due to the joint action of low temperature sulfur corrosion and erosion corrosion. The valve should be cut off or added heat tracing at the top of the tower. The corrosion of the reboiler shell at the bottom of the analytical tower is the electrochemical corrosion. It is necessary to control the sulfur content of the raw materials and to upgrade the reboiler equipment. The corrosion of the cooler tube bundles on the top of the stability tower is the inner wall scaling and metal corrosion of the tube bundles.The operation of the device showed that protective measures were proper and the corrosion risk was basically controllable．

GRAPH CONVOLUTION NEURAL NETWORK FOR PREDICTING THE OCTANE NUMBER OF PURE HYDROCARBONS IN GASOLINE

2021, 52(7):  82-87. 

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Based on the graph convolution neural network, an improved neural fingerprint method was established by introducing pooling operation. A model for predicting octane number of pure hydrocarbons in gasoline was established by this method as an important part of blending model of gasoline on molecular level. Through the verification on the boiling point and critical temperature data set, the prediction ability of neural fingerprint method was improved obviously by introducing pooling operation. The favorable and unfavorable features could be selected automatically by the improved neural fingerprint method. It was also found that the effect of double bond on motor octane number was greater than that of aromatic ring. The improved neural fingerprint method also had good results in the prediction of both research octane number and motor octane number of pure hydrocarbons in gasoline.

DECREASING OCTANE NUMBER LOSS OF PRODUCT GASOLINE FROM S Zorb UNIT USING BP NEURAL NETWORK WITH GENETIC ALGORITHM

2021, 52(7):  88-95. 

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There is usually a certain degree of octane number loss in FCC gasoline upgrading process. Based on the data over the years from a domestic S Zorb unit, 21 modeling variables from a total of 368 variables including the properties of feedstock,adsorbent,product and operating variables were screened out by grey correlation analysis and SPSS method. On the basis of clustering the feedstocks into three categories by fuzzy C-means clustering algorithm, the 21-20-1, 21-18-1, and 21-17-1 types of BP neural network models were established respectively. The verification results indicated that the accuracies of the three models established were high. The BP neural network models and genetic algorithm were combined to optimize the operating conditions for reducing the octane number loss of product on the premise of ensuring the desulfurization effect of gasoline. The predicted results can give an important reference for industrial production.

SIMULATION OPTIMIZATION OF XYLENE RECTIFICATION COLUMN AND APPLICATION BASED ON ASPEN PLUS

2021, 52(7):  96-100. 

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Xylene rectification column is the key equipment for aromatics separation with high energy consumption. Aspen Plus process simulation software was used to model the xylene rectification column of PetriChina Jilin Petrochemical Company Refinery. The accuracy of the model was verified by comparing the calculated values with the actual values. By the optimization and the sensitivity function of the software, the influence of operating conditions on the separation efficiency and the thermal load at the bottom of the xylene rectification column was studied. According to the analysis results, the energy-saving optimization of xylene rectification column was carried out by reducing the reflux rate in practical production. On the basis of ensuring product quality, the operation cost was reduced.

STUDY ON BIOLOGICAL AGENT WASHING AND MICROORGANISM DEGRADATION TREATMENT TECHNOLOGY OF OILY SLUDGE IN OIL FIELD

2021, 52(7):  101-106. 

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Oily siudge is an important part of solid pollutants in Xinjiang Oilfield. The reduction and harmlessness of oily sludge are of great significance for the control and treatment of oil pollution. In order to solve this problem, the oily sludge of Xingang Company in Xinjiang Oilfield was treated by the combination of biological agent cleaning and microbial degradation treatment, so that the oil content of oily sludge was effectively removed. The optimal reaction parameters were obtained by single factor experiment and response surface methodology (RSM). The initial oil content was 28.23%, the oil content was 6.48% after single factor optimization, and 3.04% after response surface optimization. Furthermore, Bacillus subtilis XG02 was used to degrade the oily sludge after the oily sludge was washed by the biological agent. After 20 days, the oil content of the sludge was only 0.45%, which could meet the requirements of mineral oil in the pollution control requirements of DB65/T 3998—2017.

THE INFLUENCING FACTORS OF WATER-GAS SHIFT REACTION COUPLED HYDROGENATION PROCESS

2021, 52(7):  107-112. 

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The influencing factors of water-gas shift reaction(WGSR) coupled hydrogenation of model compounds and distillates were reviewed, including the influence of catalyst and reaction conditions on in-situ hydrogenation and the interaction between different types of reactions. The influence mechanism of carbon monoxide partial pressure and water content on in-situ hydrogenation was discussed, and the important role of water in in-situ hydrogenation was analyzed and summarized. It provides an important reference for catalyst selection and reaction condition optimization in in-situ hydrogenation process.