Table of Content

12 July 2020, Volume 51 Issue 7

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STUDY OF SODIUM REMOVAL OF HIGH-SODIUM CRUDE OIL

2020, 51(7):  1-5. 

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Excessive sodium content in crude oil will lead to subsequent FCC catalyst poisoning. This paper analyzed the problem of abnormally high sodium content in de-salted crude oil of a refinery. In order to solve the problem, a sodium removal agent was developed. The effect of the sodium removal agent on sodium removal rate and on the demulsification was investigated. Based on the laboratory experiments, the agent was applied in a desalination unit. The results showed that the excessive sodium content in crude oil after electric desalination was caused by the excessive sulfonates used as crude oil recovering agent in oil field. The addition of sodium removal agent can break the equilibrium of petroleum sodium sulfonates distribution between the oil phase and water phase, and makes more sulfonates entering into the water phase, thus decreasing the sodium content in desalted crude oil. The industrial test in No.2 electric desalting unit showed that the sodium removal rate increased from 75.7% to 84.2% with the addition of the sodium removal agent.

INDUSTRIAL APPLICATION OF DOMESTIC SULFURIC ACID ALKYLATION TECHNOLOGY

2020, 51(7):  6-10. 

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In order to meet the needs of China phase-VI gasoline, a new alkylation unit is imperative. The new 0.20 Mt/a alkylation unit of SINOPEC Luoyang Company adopted the SINOALKY, a sulfuric acid alkylation technology, independently developed by SINOPEC. Industrial results confirmed that the technology has the advantages of simple process, easy maintenance of reactor, low acid consumption and good product quality. When the reaction temperature was 0 ℃, the octane number of alkylate was 97, acid consumption was 65 kg/t alkylate, while unit energy consumption was 4598 MJ/t . Since the start of the unit, the process parameters and the operation of the unit has been stable, it can produce more than 16 kt of alkylae per month, which fundamentally solves the problem of gasoline blending and creates economic benefits of nearly 10 million Yuan for the company per month.

INFLUENCING FACTORS OF ETHYLENE LOSS IN DEMETHANIZER SYSTEM OF ETHYLENE PLANT AND CORRESPONDING MEASURES

2020, 51(7):  11-15. 

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Demethanizer system is the key of cryogenic separation in ethylene plant, which can influence the loss of ethylene products. The loss of ethylene is often related to the design and operation of demethanizer system. Taking a demethane tower system in the former depropane process of ethylene plant as an example, the influencing factors, such as methane/hydrogen mole ratio of feed and feed temperature, setting of ethylene scrubber, reflux of demethanizer and overhead temperature, as well as heat load of reboiler/condenser were studied. And the solutions were proposed to reduce ethylene loss in the demethanizer top and provided reference for the design and operation of demethane tower system in ethylene plant.

ANALYSIS OF COKING IN DISENGAGER AND APPLICATION OF ANTI-COKING TECHNOLOGY WITH DIRECT CONNECTION AND OVERFLOW BUCKET

2020, 51(7):  16-20. 

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Based on the comparing the operating parameters and coking situations in the first and second operating cycles of the 2.0 Mt/a FCC unit of SINOPEC Yangzi Petrochemical Co. Ltd., the causes of the coking in disengager were analyzed. It was determined that the coking in the disengager is caused by poor cyclone matching and the long oil and gas retention time in the disengager. For this reason, the soft connection of the disengager was changed to a direct coupled plus overflow bucket configuration. The results showed that the disengager coking was effectively avoided, while reducing the dry gas, diesel and coke yields by 0.26, 0.25 and 0.54 percentage point, respectively. The yield of LPG, gasoline and slurry was increased by 0.54, 0.33 and 0.18 percentage point, respectively. The solid content of the slurry was reduced from 4.1 g / L to 2.0 g / L, showing excellent anti-coking and improved operating effects.

COMPLEXATION DESULFURIZATION OF HYDROFINING DIESEL BY METAL CLORIDES

2020, 51(7):  21-26. 

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Benzothiophenes were the main residual sulfides in hydrofining diesels. Based on the complexation mechanism between thiophenes and metal ions, four kinds of metal chlorides such as CuCl2, AlCl3, FeCl3 and MnCl2 were selected as complexation desulfurizers for desulfurization research on shallow hydrogenated diesel with sulfur mass fraction of 592 μg/g. The results indicated that at the same conditions, the desulfurization effect of AlCl3 was the best in one-component metal chloride, and that of CuCl2 /AlCl3 in two-component metal chloride was the best when the mass ratio of CuCl2 /AlCl3 was 1:1. Considering the process cost and operation cycle, the optimum process conditions were as follows: 50 ℃, reaction 30 min with the mass fraction of complex desulfurizer of 10%. Under optimal process conditions, the desulfurization rate of AlCl3 can reach 86%, and that of CuCl2/AlCl3 can reach 95% when the mass ratio of CuCl2/AlCl3 was 1∶1.

REFACTION PERFORMANCE OF HYDROGENATION VGO ON CATALYTIC CRACKING CATALYSTS WITH DIFFERENT AGING TIME

2020, 51(7):  27-32. 

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The effects of aging time of FCC catalyst on the distribution of reaction products, gas and gasoline composition were investigated in a small fixed fluidized bed unit with hydrotreated VGO as raw material under the conditions of a reaction temperature of 500 ℃, a water injection rate of 10%, a mass space velocity of 10h-1 and a mass ratio of catalyst to oil of 6. The results showed that the effects of catalyst aging time had a good correlation with the acid amount and specific surface area of catalyst. When the catalyst aging time exceeded 8 h, the yields of dry gas and coke were relatively low,while the total liquid yield was relatively high. When the catalyst aging time was more than 25 h, it was beneficial to achieve high propylene yield and control propane yield. The benzene content of total aromatics in gasoline was not affected by aging time. The reduction of the benzene content in gasoline product of different production schemes could be achieved by reducing the total amount of aromatics through changing catalyst aging time by adjusting the amount of cracking catalyst supplement.

STUDY ON CATALYTIC CRACKING PERFORMANCE OF HIGH STABILIZED ZEOLITES

2020, 51(7):  33-38. 

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A series of highly stabilized zeolites（HSZ）with different cell sizes was designed and manufactured by changing the degree of cation exchange and gas phase super stabilization in commercial scale. The catalysts were prepared with HSZ-3，HSZ-4，HSZ-5 zeolites as active component and their catalytic cracking performances were investigated and compared by using automated micro activity test and ACE fixed fluid bed reactor. The results showed that the catalysts with gas phase super stabilized zeolite as active component possessed stronger heavy oil cracking ability，higher yield of gasoline，light oil and total liquid，and better coke selectivity compared with the catalysts using hydrothermal stabilized zeolite as active component.

COMMERCIAL APPLICATION OF C8 AROMATICS ISOMERIZATION CATALYST RIC-270

2020, 51(7):  39-42. 

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A new generation catalyst RIC-270 with higher activity, selectivity and stability for xylene isomerization was developed by SINOPEC Research Institute of Petroleum Processing and applied in the aromatics complex unit of SINOPEC Jinling Company in January 2020. Dense phase loading technology was adopted. And a new soft flow-guiding sealing cloth RKJ-1 at the upper part of the catalyst bed was used to replace the baffle plate. Industrial data showed that the isomerization activity（the mass ratio of PX/X）of the catalyst was 23.2%, ethylbenzene conversion rate was 30%, and C8 aromatics loss was only 2.4%. The initial reaction temperature and pressure of RIC-270 were relatively low,which indicated that RIC-270 had the potential of long-term stable operation.

CAUSE ANALYSIS OF REDUCTION OF HYDROGENATION CATALYST ACTIVITY

2020, 51(7):  43-48. 

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In order to study the deacidification, desulfurization and denitrification activities of hydrotreating catalysts under different conditions and the reasons for the activity reduction, the hydrogenation experiments were carried out with WO3-NiO/Al2O3 as the catalyst and Suizhong vacuum gas oil as feed. The activity stability of the catalysts under severe conditions was investigated byraising temperature and pressure. The results showed that the activity of the catalyst decreased after 600 h ofreaction under high temperature and high pressure, but the specific surface area, pore volume, average pore size and pore size distribution of the catalyst changedslightly compared with the same catalyst without temperature and pressure rise. The results of catalyst characterization show that the reasons for the decrease of activity are the higher carbon content, the reduced content of W4+ and NiWS phase with high activity and the increased content of NiS, W5+ and W6+ with low activity in the active component.

STUDY ON GAS PHASE HYPERSTABILIZATION OF SMALL CRYSTALL SIZE Y ZEOLITE

2020, 51(7):  49-54. 

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In order to solve the problem of poor thermal stability and hydrothermal stability of small crystal size Y zeolite, the USY zeolites were prepared by SiCl4 gas phase hyperstabilization using different particle size NaY zeolites as raw materials. The effects of different particle size and different silicon-aluminum ratios on physicochemical properties, MAT activity and hydrothermal stability of Y zeolite were investigated. The results showed that the hydrothermal stability of small crystal size Y zeolite could be greatly improved by the SiCl4 gas phase hyperstabilization where the skeleton aluminum was substituted by silicon. After the hydrothermal treatment at 800 ℃, 4 h, 100% steam, the crystallinity retention and acid properties of small crystal stablized Y zeolite with crystal size about 700 nm and crystal lattice constant over 2.440 nm were similar to those of gaseous stablized traditional Y zeolite. Since small crystal zeolites had much more active centers on the external surface, leading the large molecular, which could hardly diffuse into the zeolite canal, more conducive to react. The conversion of 1, 3, 5-triisopropylbenzene could increase 15-23 percentage points on the SiCl4 stabilized Y zeolite with small crystal size, compared with gaseous stablized ordinary Y zeolite.

RESEARCH ON ULTRA-STRUCTURE OF MONORAPHIDIUM AND EXTRACTION OF LIPID THROUGH AQUEOUS ENZYMATIC PROCESS

2020, 51(7):  55-60. 

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The morphology and ultra-structure of Monoraphidium were studied with the transmission electron microscope and the aqueous enzymatic method. The cell of the algae was quasi-ellipse smoothing surface without flagellum and the thickness of its cell wall was about 50 nm. The cell wall was mainly composed of cellulose and hemicelluloses. The extraction of lipid from the Monoraphidium through aqueous enzymatic process was investigated. The results showed that the combination of the alkaline pretreatment and the enzymatic treatment subsequently and then the dual solvent system extraction was the most effective process. Under the mild reaction conditions, the lipid yield of monoraphidium with cellulose enzyme reached more than 13% with the extraction rate more than 80%. In addition, it was found that the content of saponifiable lipid extracted by n-hexane was higher than that by trichloromethane. The fatty acids, containing 71.59% of saturated and Monounsaturated fatty acid, with a lower degree of unsaturation (DU) of 97.20% and the main carbon number of C16—C22 was obtained from lipid in Monoraphidium, which could be used as feed to produce biodiesel.

EFFECTS OF BLENDING ETHYLENE TAR ON COLLOIDAL STABILITY OF DELAYED COKER FEEDSTOCK AND PYROLYSIS PROCESS

2020, 51(7):  61-64. 

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The n-d-M method, E-d-M method and hydrocarbon group (PONA) analysis method were used to analyze the composition and properties of the existing delayed coker feedstocks(vacuum residue,FCC slurry) and ethylene tar. The conductivity and thermal weight loss (including TGA and DTA) of feedstocks were measured, and the influence of blending ethylene tar on the stability and pyrolysis process of delayed coker feedstocks colloid was studied. The results showed that blending ethylene tar in the existing delayed coker feedstock would lead to a decrease in the saturation and an increase in the aromatic content of the feedstock. In the case at 35 oC, the colloidal stability parameters of delayed coker feedstocks increased with the increase of the ethylene tar blending ratio, and the colloidal stability was improved in a certain range. In addition, the mixing ethylene tar would lead to the coking reaction trend in advance and higher coke yield, and the yield of each distillate in the product would change significantly. It proves that the pyrolysis process and the pyrolysis products compositions are complicated after mixing ethylene tar.

EFFECT OF SYNTHETIC BASE OIL ON PROPERTIES OF LITHIUM GREASE

2020, 51(7):  65-69. 

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Five kinds of lithium grease samples were prepared under the same content of lithium soap and the same technological conditions by using poly-α-olefin synthetic oil and diester synthetic oil as base oil in five different proportions. The influence of synthetic base oil with similar viscosity and different types on the performance of lithium grease was analyzed through the thermal stability, low temperature type, shear stability and colloidal stability of five kinds of lithium grease samples. The results show that the shear stability and colloidal stability of the lithium grease prepared from diester synthetic oil are better than the lithium grease prepared from poly-α-olefin synthetic oil, while the lithium base grease prepared from poly-α-olefin synthetic oil has excellent thermal stability and low temperature performance due to the low pour point and low evaporation loss at high temperature.

DEVELOPMENT OF LUBRICATING OIL FOR ELECTRIC VEHICLE TRANSMISSION SYSTEM

2020, 51(7):  70-74. 

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Lubrication characteristics of transmission system and the standard of General Motors were analyzed in order to understand the lubrication requirements for pure electric passenger vehicles. The oil was mixed with base oil of API Ⅲ+ hydrogenated mineral oil, ester oil and extreme-pressure and anti-wear additives, metal passivator, anti-rust, ashless dispersant. The physical-chemical and friction tests showed that the oil had good properties of thermal oxidation stability, shear stability, insulation, anti-rust and anti-corrosion, extreme-pressure and anti-wear additives, anti-friction. The oil performance is superior to the automatic transmission oil used in an electric passenger car.

PRODUCT STRUCTURE OPTIMIZATING SOLUTION OF HYDROCRACKING UNIT AND EFFECT

Zhang Hongliang

2020, 51(7):  75-79. 

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In view of the fact that the demand for diesel fuel in the domestic oil product market is decreasing while the demand for jet fuel，heavy naphtha and hydrocracker tail oil is increasing，SINOPEC refining and chemical enterprises have flexibly adjusted the product scheme through adopting new hydrocracking catalyst to replace partly original catalysts, grading hydrocracking catalysts with different performance, optimizing product cutting solution and producing white oil from diesel fraction. The yields of jet fuel，heavy naphtha and hydrocracker tail oil were improved and the yield of diesel was reduced. The qualities of jet fuel and tail oil products were also improved. After implementation，the yield of jet fuel of hydrocracking unit increased by 3.58-13.28 percentage points，and the yield of diesel decreased by 5.14-5.81 percentage points; the ice point of jet fuel was declined by more than 1 ℃，and the BMCI of tail oil declined by 1.2-1.7.

PROCESS SIMULATION AND OPERATION OPTIMIZATION FOR INCREASING FIRST SIDE LINE OIL OF ATMOSPHERIC DISTILLATION UNIT

2020, 51(7):  80-85. 

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After revamping the atmospheric column of atmospheric and vacuum distillation unit in SINOPEC Luoyang Company, the light oil yield increased. The production adjustment is guided by benefit, and the optimization work is carried out around increasing the output of jet fuel. A model of off-line operation optimization was established to optimize the first side line oil with PETRO-SIM. The results of simulation showed that the end point of overhead naphtha had a greater impact on the output and properties of the first side line oil. The optimizing target of increasing the output of the first side line oil was realized by adjusting the flow rates of stripping steam into bottom of atmospheric tower and the second side line oil stripper, the flow rate of the second side line oil, as well as the end point of naphtha at the atmospheric tower top. During the optimization, the problems of low utilization of high temperature potential heat source in atmospheric pressure tower and lack of naphtha in jet fuel fractionator in jet fuel hydrogenation unit were found, and the solutions were put forward.

STUDY ON PROCESSING ROUTES FOR NEW REFINERY WITH 10 Mt/a CAPACITY

2020, 51(7):  86-92. 

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In this paper, processing routes for a new refinery with ten million tons capacity were studied, and the impacts of different processing routes on unit configuration, product structure, investment and economic benefits were discussed. The results showed that it is feasible for a ten million tons refinery to produce chemical products and aromatics. When the scale of ethylene and PX is constant, the slurry bed residue hydrocracking + fixed bed residue hydrotreating + catalytic cracking route has the highest yield of oils (including gasoline, kerosene and diesel), while the slurry bed hydrocracking + deep catalytic cracking route has the highest yield of gasoline, and the slurry bed hydrocracking + VGO hydrocracking route has the highest yield of kerosene and diesel. From the aspect of chemical product, combined technology of residue hydrocracking, residue hydrotreating and deep catalytic cracking can increase the yield of ethylene and propylene about 4%-5%, 5%-6%, respectively. The slurry bed hydrocracking + VGO hydrocracking route has the lowest investment and the highest benefit rate and is a better and shorter processing route to realize transformation of refineries than other routes.

ANALYSIS OF SCALE SAMPLE IN HIGH PRESSURE HEAT EXCHANGER OF VGO HYCROCRACKING UNIT AND SOLUTIONS

Han Longnian Xin Jing Chen Yufei

2020, 51(7):  93-98. 

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In view of heat exchange efficiency reduction of the high pressure heat exchangers of VGO hydrocracking and the pressure drop continuously rise，the high pressure exchangers were cleaned and the scale samples were analyzed. The X-ray fluorescence spectrometer（XRF），scanning electron microscope（SEM）and X-ray diffractometer（XRD） and other analysis techniques were used to analyze the sample after toluene extraction. The results showed that the main inorganic components in scale sample were Fe2P4O12 and FeS. In addition, it also contained a small amount of inorganic materials containing Si and Na and a small amount of organic scales. In view of this, it is suggested that refineries strictly control the carrying of phosphorus-containing substances in hydrocracking feed oil, and protect equipment and pipelines from corrosion by naphthenic acid as much as possible.

CARBON DIOXIDE CORROSION OF DEHYDROGENATION EXHAUST OF STYRENE UNIT AND MEASURES

2020, 51(7):  99-103. 

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Corrosion of dehydrogenation exhaust system was mainly concentrated in inlet pipes of cooler, casing head and outlet of cooler in styrene unit, with typical local corrosion morphology by CO2, such as pit corrosion, trench corrosion and platform corrosion. The corrosion mechanism was the galvanic corrosion caused by the different coverage of FeCO3 corrosion products on the metal surface. The operation results showed that the corrosion of CO2 was slight toward austenitic stainless steel equipment and pipeline, but serious for carbon steel equipment and pipeline and that the system process, temperature, material and pipeline structure provide the environment condition and promotion for the occurrence and development of carbon dioxide corrosion. In view of the process flow and corrosive environment of the system, the solutions of replacing the material and adding neutralizing corrosion inhibitor was put forward and the good results of anti-corrosion achieved.

DEVELOPMENT IN THE SYNTHESIS AND APPLICATION OF MICROPOROUS MOLECULAR SIEVE ZSM-22

2020, 51(7):  104-112. 

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ZSM-22 molecular sieve has medium-strength surface acidity and appropriate pore structure and exhibits excellent catalytic activity in many reactions, such as long-chain alkane isomerization and olefin isomerization. The catalytic activity, selectivity, thermal stability and operational life of ZSM-22 are mainly dependent on their physicochemical properties, e.g pore structure, surface acidity, grain size, and chemical composition of crystal. It is very important for catalyst design to understand the influence of physicochemical properties on catalytic performance. By comparing the characteristics of different synthesis methods of ZSM-22 molecular sieve, the effects of synthesis methods on the activity, selectivity, structure and other physical and chemical properties of molecular sieve were analyzed. The application status of ZSM-22 molecular sieve, the optimization of the application results and the extension of the range were summarized.