Table of Content

12 February 2016, Volume 47 Issue 2

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STUDY OF CORROSION ON CARBON STEEL BY ALUMINUM SOL

2016, 47(2):  1-4. 

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The corrosion of aluminum sol on carbon steel was studied through the weightlessness of the steel sample soaked in the sol. The corrosion products were characterized by means of IR and SEM, and the formation mechanism of the corrosion products was analyzed. It is discovered that the corrosion products are mainly composed of α-FeOOH, γ-FeOOH and Fe3O4, and the presence of chloride ions in aluminum sol destroys the structure of the passivation film on the surface of the carbon steel to accelerate the corrosion of carbon steel, resulting in the formation of corrosion products.

INFLUENCE OF CALCINATION ON PERFORMANCE OF SPHERICAL ADSORBENT

2016, 47(2):  5-8. 

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To obtain the spherical adsorbent with good adsorptive performance and high strength, the influence of dry air flow rate and bed thickness on the crystallinity of FAU zeolite in the adsorbent, as well as the calcination temperature and dry air flow rate effect on the adsorbent strength were investigated systematically. The X-ray diffraction measurement (XRD), thermogravimetric analyzer (TG) and intelligent particle strength tester were employed to characterize the samples. It is found that the higher flow rate of dry air and smaller bed thickness are in favor of lowering air humidity in the adsorbent bed, and consequently reducing the hydrothermal damage of FAU zeolite and remaining its crystlinity. The higher the calcination temperature, the higher the strength of the spherical adsorbent. When the calcination temperature exceeds 500 ℃, the binder, halloysite, in the adsorbent, is transformed into amorphous material, resulting in higher strength of the adsobent. The adsorbent strength also increases with the increase of dry air flow rate.

NUMERICAL SIMULATION OF BUBBLE COLUMN REACTORS WITH DIFFERENT NOZZLES OR DISTRIBUTORS

2016, 47(2):  9-15. 

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Three-dimensional numerical simulations of bubble column reactors with different nozzles or distributors were conducted using Euler-Euler multiphase model and RNG k-ε turbulence model. The gas holdup and axial liquid velocity in reactors were analyzed and compared. The results indicate that the liquid circulation flow is formed in all reactors. Venturi nozzle and multi-nozzle are proved to be more effective than single-nozzle. A uniform gas holdup distribution and a large-scale liquid circulation can be provided by ring and calandria liquid distributors, indicating the better performance than that of three nozzles tested.

NUMERICAL SIMULATION OF EFFECT OF FCC FEED ATOMIZING NOZZLE STRUCTURE ON INTERNAL FLOW FIELD AND MIXING CHARACTERISTICS

2016, 47(2):  21-25. 

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By using CFD method and multiphase flow model , based on the Euler-Euler method,the internal flow field of an internal mixed catalytic cracking feed atomizing nozzle is si-mulated. The distribution of gas-liquid flow field in the nozzle and their mixing characteristics ar-e studied.In order to enhance the entire perforamce of the nozzle,a helical structure is built into it, and the comparative simulation is conducted.The results show that the original structure of the two-phase distribution is relatively concentrated,the tangential velocity of the fluid is almo-st zero,this makes the atomization effect of the nozzle drops,and limited spray range ;the h-elical structure can rotate the fluid inthe mixed chamber and thus fluid obtains a tangential velocit-y with the maximum value of 18.49 m/s. In additon,the turb-ulence intensity of two-phase flow is increased and the average velocity is effectively raised.So the atomization performance of the spr-ay nozzle is finally enhanced.

STUDY ON THERMAL DECOMPOSITION OF TYPICAL CORROSION INHIBITORS USED IN OILFIELDS

2016, 47(2):  26-31. 

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A great number of oilfield chemicals are used in oil fields for enhancing oil recovery and oil transport in China. Some of these chemicals directly come into crude oils, resulting in the corrosion of refinery equipments. It was thought that the corrosion inhibitor is believed to be one of the causes of equipment corrosion. The thermal decomposition simulation experiments were performed to understand the changes of typical corrosion inhibitors in oil refining processes. The mechanism of these changes leading to the corrosion was analyzed. It is found that as the decomposition temperature rises, the concentration of inorganic Cl- increases in inhibitors tested at 120 ℃ and increases markedly at 360 ℃, compared with the one before heating. It is concluded that the production of Cl- is due to the hydrolysis or cracking reactions of some of stable compounds in corrosion inhibitors.

DIAGNOSIS FOR CCR CATALYST REPLACEMENT

2016, 47(2):  32-37. 

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Based on the analysis of specific surface area, the damage extent of support crystal phase, Pt dispersion, and metal impurity pollution of the CCR catalyst at the end of run, the difference between fresh catalyst and the catalyst in operation was quantitatively compared by using simulation calculation and laboratory activity test. The technical parameters for catalyst replacement were proposed by comparison of the physicochemical properties, catalytic activity and the unit economy between fresh catalyst and the catalyst at different time on stream. When the specific surface area of catalyst in operation is less than 140-145 m2/g, and the activity decreases by 4-5 ℃ and the yield of C5+ decreases by 1.5~2 percentage points, the catalyst in service must be replaced to reduce the operation risk and boost the economic benefit of CCR unit.

PROPERTIES AND STRUCTURE STUDY OF NI/Y CATALYST

2016, 47(2):  38-41. 

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A series of Ni/Y catalysts were prepared using incipient impregnation method. The effect of Ni loading on the microstructure and activity of the catalysts were investigated by the means of BET, XRD, NMR, and TEM. The results showed that the crystallinity, specific surface area, pore volume and the amount of Br?nsted type acid all decreases with increasing amount of Ni loading, but the hydrogenative regeneration activity of catalysts first increases then decreases with increasing amount of Ni loading. 2Ni/Y with 2.0% Ni loading has the best hydrogenative regeneration activity, which can regenerate 92.8% catalyst life. This mainly because that Ni is the active center of hydrogenation, the number of Ni active site increases with increasing Ni loading, but Ni dispersion decreases when Ni loading is too large, and the number of Ni active site decreases, thus hydrogenative regeneration activity of the catalysts would decrease.

STUDY OF ISODEWAXING CATALYST FOR HYDROCRACKING TAIL OIL TO PRODUCE LUBE BASE OIL

2016, 47(2):  42-46. 

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The influence of ZSM-22 content in isodewaxing catalyst TH-2 on yield and pour point of base oil from hydrocracking bottom oil was studied. The results show that with decrease of the molecular sieve content, the activity of catalyst decreases and the base oil yield increases. When Huizhou unconverted oil(UCO) were used as the feed，the best reaction conditions for TH-2 are 320 ℃, 14.0 MPa, hydrogen to oil ratio of 600:1 and LHSV=1.1 h-1. After 1 000 h running, TH-2 catalyst performance is stable and the pour point of 150N base oil is -18 °C, the total base oil yield is 77.2%.

METHANOL AROMATIZATION PERFORMANCE OF ZSM-5 MODIFIED BY NaAlO2

2016, 47(2):  47-52. 

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ZSM-5 zeolite was modified successively by sodium aluminate and HCl washing with a calcination between the two steps. The samples were characterized by XRD, SEM, NH3-TPD, N2 adsorption, ICP-OES, and TG techniques. The results show that mesopores were created, and a higher solid yield was obtained with the crystallinity, acidity and micropore volume largely preserved. Besides, the calcination before acid washing is in favor of eliminating the pore blocking and recovering the acidity. The methanol aromatization performance over the modified catalysts was investigated at the conditions of 400 ℃, 0.15 MPa and the weight hourly space velocity of 1.9 h-1. The ZSM-5 zeolite modified with 0.45 mol/L NaAlO2 presents the optimal performance. The aromatics yield reaches 41.9% and BTX yield is 32.7%, increased by 3.8 and 4.4 percentage points compared with catalytic activity of parent ZSM-5, respectively. Meanwhile, the modified catalyst’s lifetime is 30h, one more times than the parent zeolite.

PREPARATION OF ZSM-11 ZEOLITE CATALYST MODIFIED BY SILVER AND ITS CATALYTIC CRACKING PERFORMANCE FOR HEAVY OIL

2016, 47(2):  53-59. 

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The ZSM-11 zeolites with micro-meso porous were modified by Ag species, followed by incipient impregnation to prepare catalysts. The modified zeolites and catalysts were characterized by XRD, FT-IR, NH3-TPD, UV-Vis and N2 adsorption-desorption. The results indicated that small amounts of Ag had little influence on the structure of ZSM-11. Ag+, Agn+ and Agm were the main states of Ag on modified ZSM-11 zeolites. Besides, Ag species affect the acidity of the samples and increase the strong Lewis acidity. The heavy oil catalytic cracking performance of the catalysts was investigated in a fixed micro-reactor. The results indicated that the addition of small amount of Ag can enhance greatly the hydrothermal stability and the catalytic activity. However, larger Ag loadings favore the formation of dry gas and coke due to more strong Lewis acidity formed, resulting in the decrease of selectivity to light olefins.

SYNTHESIS OF DISCARBOXYL PHENOXY PHTHALOCYANINE COBALT AND APPLICATION IN OXIDATION DESULFURIZATION OF MERCAPTAN COMPOUNDS

2016, 47(2):  60-64. 

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The 4-(3,5-dicarboxy) phenoxyphthalonitrile as an intermediate was synthesized with 4-Nitrophthalonitrile and 5-hydroxy isophthalic acid as raw materials, followed by the purification by column chromatography. Afterwards, a new tetra -2(3), 9(10), 16(17), 23(24) - (3,5-discarboxylphenoxy) phthalocyanine cobalt was obtained from the intermediate under the catalytic action of 1,8-diazabicyclo undec-7-ene (DBU). The intermediate and the final product were characterized by mass spectrum, Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (1H-NMR) and MADLI-TOF-MS techniques. The sweetening performance of the synthesized phthalocyanine cobalt was evaluated using mercaptan compounds and compared with the industrial catalysts. The sulfur conversions of n-propyl mercaptan and n-butyl mercaptan of the synthesized phthalocyanine cobalt are both around 98.0%, and for t-butyl mercaptan the conversion is 68.2%. The results show that the sweetening performance of the synthesized phthalocyanine cobalt is better than the industrial catalysts.

DEVELOPMENT AND APPLICATION OF DENITROGENATION AGENT FOR DEEPLY NITROGEN REMOVAL FROM LOW TEMPERATURE ISOMERIZATION FEED

2016, 47(2):  65-68. 

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A new denitrogenation agent and a relative process were developed to deeply remove basic nitrogen impurities from the light naphtha (topped oil) of distillation column of reforming feed prehydrogenation unit. Through the lab test in a fixed-bed down-flow reactor, the optimal conditions of denitrogenation process were determined as follows: 40 ℃of adsorption temperature, 0.5-1.0 MPa, space velocity=5.0-10.0 h-1. The technology has been successfully applied in an isomerization unit with 0.3 Mt/a of Sinopec Tahe Petrochemical Co. The results show that the nitrogen content of the light naphtha is lower than 0.1 μg/g, meeting the requirement of the subsequent low temperature isomerization process. The octane number of the isomerization product is 20 percentage points higher than that of feed.

PRESULFIDATION BY WAX OIL FOR RESIDUE OIL HYDROTREATING CATALYSTS

2016, 47(2):  69-73. 

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The wax oil as a sulfidation agent carrying oil was firstly used for residue hydro treating catalysts at both high and low temperature presulfidation process in a commercial unit. The method avoids the switching between diesel oil and wax oil in conventional presulfidation process, thus shortening start-up time more than 20 h. The fluid distribution in catalyst bed and the activity of the catalysts presulfided by wax oil were analyzed in terms of temperature changes during catalyst wetting, reactor pressure differential, radial temperature difference, and uneven temperature distribution index of bed and compared with the conventional process using diesel as a presulfidation agent carrying oil. It is concluded that the fluid distribution is even in the wax oil presulfidation process and the presulfiding effect meets the process requirements.

ANALYSIS OF OPERATION FLUCTUATION OF SOLVENT REGENERATION TOWER IN SOUR GAS DESULPHURIZATION SYSTEM AND ITS OPTIMIZATION

2016, 47(2):  74-78. 

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The reasons for operation fluctuation in the ethanol amine solvent regeneration tower of the sour gas desulphurization system were analyzed. The flood phenomena increased the loss of diethanol amine and affected the quality of dry gas and liquefied gas. Based on the analysis, the following operation parameters were required to solve flood problem: the steam temperature from the bottom of the regeneration tower was controlled at 115-120 ℃, the heavier component in liquefied gas and the dry gas were reduced to less than 1.5% and 2%, respectively, the pressure of flash tank of rich diethanol amine solution was set at 0.30 MPa, the load of filtered diethanol amine was adjusted to 3 t/h. These measures make the operation stable, and assure the qualities of dry gas and LPG products. The loss of diethanol amine is reduced and the economic benefits of enterprises are increased.

DEVELOPMENT OF SPECIAL WAX WITH HIGH HARDNESS AND LOW MELTING POINT

2016, 47(2):  79-83. 

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The waxes were modified by addition of polyethylene wax and lauric acid with perfect mixing for lowering drop melting point and strengthening hardness of the waxes. The modification conditions and the effect of additives on the properties of the waxes were investigated. The experimental results show that to prepare the ideal special waxes with low drop melting point and high hardness, the best conditions for modification are 130 ℃, 3h and stirring speed of 600 r/min with addition of lauric acid 8% and polyethylene wax 5%. If polyethylene wax, lauric acid and stearic acid are mixed used as additive (5%:8%:0-25%), the waxes with even lower drop melting point and stronger hardness can be obtained. Based on the results, a relationship of the amount of polyethylene wax, lauric acid and stearic acid with drop melting point as well as penetration (25 ℃) is presented by using SPSS software and linear regression method.

WATER SPARATION AND OIL/WATER INTERFACIAL PROPERTIES OF BASE OILS FOR MARINE DIESEL ENGINE

2016, 47(2):  84-88. 

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According to SH/T 0619，the water separation properties of HVIⅡ-10，HVI750，HVI150BS base oils for marine diesel engine lubricant were determined after the addition of the same composite additive. The relationships between water separation and oil/water interfacial tension as well as interfacial shear viscosity were then investigated. The results show that the water separation abilities become worse in the order of HVIⅡ-10，HVI750，HVI150BS, the interfacial tension lowers and the interfacial shear viscosity rise in the same order. It is found that the more aromatics and resins in the base oils, the poorer the water separation property. The additive reduces the interfacial tension and increases the interfacial shear viscosity of the system, resulting in more stable emulsion. The shear viscosity decreases as the shear rate increases. It is concluded that the lower the interfacial tension, the higher the interfacial shear viscosity, the greater the stability of the emulsion, and the poorer the water separation.

SIMULATION ANALYSIS OF DIOLEFIN HYDROGENATION OF FCC GASOLINE IN CATALYTIC DISTILLATION

2016, 47(2):  89-92. 

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The hydrogenation-catalytic distillation process for diolefin removal from FCC gasoline was simulated and analyzed using Aspen Plus software, and the influence of reflux ratio, H2/oil volume ratio, space velocity, reaction temperature and reaction pressure on the diolefin hydrogenation efficiency were investigated. Results showed that the diolefin removal rate of FCC gasoline increased with the increasing of reaction pressure, while increased with the decreasing of space velocity, reflux ratio, and H2/oil volume ratio. The results obtained could be useful for the operation condition optimization and process design of the hydrogenation-catalytic distillation for diolefin removal from FCC gasoline.

MULTI-OBJECTIVE OPTIMIZATION OF MULTI-PRODUCT PLAN FOR FLUID CATALYTIC CRACKING SEPARATION SYSTEM

Hong-Jin DAI

2016, 47(2):  93-97. 

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Based on the simulation of a FCC separation system using Aspen Plus software, where the gasoline end point, diesel 95% point, C2 and C3 volume fraction in dry gas and LPG, respectively were used as the constrain conditions, a multi-objective model of maximizing the yield of product, minimizing the energy consumption of separation system is established in consideration of multi-product plan. Multi-objective line-up competition algorithm (MOLCA) was employed to solve the model, and the Pareto front obtained from the model reveals the influence rule of the energy consumption on the yield of product. The results indicate that the optimal compromise solutions of operation parameters are superior to that of real practice.

ANALYSIS ON DEVELOPMENT OF CHINA REFINING INDUSTRY IN FUTURE AND SUGGESTIONS

2016, 47(2):  98-102. 

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The development for China’s oil refining industry during the Twelfth Five-year Plan period is briefly overviewed. During the thirteenth five-year plan period, the main problems and situation Such as deceleration of oil demand, the continued decline of diesel-gasoline ratio, refining overcapacity, intense market competition, the strict criterion of oil quality and environmental protection for refining industry are analyzed, with macroeconomic to new normal, related industry policy, regulations and standards, etc.. Suggestions on the main development ideas and measures are put forward, such as restriction of new refining capacity, optimization of current refinery. Simultaneously, it is suggested that heavy oil conversion, diesel conversion, alkylation and other related technologies should be applied to improve high value-added products yield, adjust product structure and upgrade oil quality, in order to build green, intelligent and efficient refinery.