Table of Content

12 August 2015, Volume 46 Issue 8

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STUDY ON INCREASING LIGHT AROMATICS PRODUCTION IN DEEP CATALYTIC CRACKING OF HEAVY OIL

2015, 46(8):  1-6. 

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The effect of reaction temperature, catalyst/oil ratio, WHSV, and water/oil mass ratio on product distribution, light olefins and light aromatics yields was investigated using pipeline VGO as a feedstock. The best process parameters are: 560 ℃, ratio of catalyst to oil (C/O) of 6, WHSV of 2h-1 and water to oil (W/O) of 10. Daqing VGO and intermediated pipeline VGO were employed as cracking feedstocks to examine how feedstock properties impact on the yields of light olefins and light aromatics under the same conditions. The results indicate that the paraffin based feedstock is better in maximizing yields of light olefins and light aromatics, even more light aromatics can be produced at larger catalyst/oil ratio. Using paraffin base VGO, more light olefins and aromatics can be obtained simultaneously. The pathway of light aromatics formation was investigated. It is discovered that most light aromatics are formed by breaking side chain of the mononuclear aromatics when the conversion is low, while the light aromatics from dehydrocyclization of olefins becomes gradually the main pathway when the conversion is higher.

TECHNICAL ROADMAP AND BENEFIT ANALYSIS FOR NATIONAL PHASE V GASOLINE PRODUCTION

2015, 46(8):  7-11. 

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The cost and benefit of producing national phase V gasoline in a 2 Mt/a VGO FCC unit using MIP or conventional catalytic cracking technology with S Zorb, alkylation and MTBE technologies are analyzed. Compared with the conventional catalytic cracking, MIP technology has higher gasoline yield, lower production cost, resulting in a better benefit. Although gasoline quality upgrading increases the cost of refinery, it can be compensated through technological advances largely.

DEVELOPMENT AND COMMERCIALIZATION OF CLEAN FUELS PRODUCTION TECHNOLOGY FROM MEDIUM AND LOW TEMPERATURE COAL TARS

2015, 46(8):  12-17. 

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Two-stage hydrogenation process of high pressure hydrotreating and hydrocracking is adopted to produce clean fuels from medium and low temperature coal tars. The technology developed by Fushun Research Institute of Petroleum and Petrochemical (FRIPP) is applied in a coal tar hydrotreating unit with a capacity of 160 kt/a. The <500 ℃ fraction after pretreatment of coal tar was used as a feedstock. Under the reaction conditions of 15.0 MPa, oil/ hydrogen volume ratio of 1 000, hydrotreating temperature of (base+10) ℃ and Sv of (base+0.2)，hydrocracking temperature of (base+30) ℃ and Sv of (base+0.2), the sulfur content and octane number（RON）of the fraction below 160 ℃ is 3.3 μg.g-1 and 65.3, respectively, which could be used as a low sulfur naphtha; the diesel fraction of 160～375 ℃ has a density of 0.852 5 g.cm-3, the cetane number is as high as 49.5, and the solidifying point is -10 ℃, which could be used as a high quality diesel blending component; fraction beyond 375 ℃ with sulfur of 2.6 μg.g-1 and the aromatics of 2.0% could be used as a good raw of lube base oil.

REASERCH ON COAL TAR ATMOSPHERIC RESIDUE HYDROCRACKING IN SLURRY-BED AND PILOT SCALE TEST

2015, 46(8):  18-23. 

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The hydrocracking experiment of medium temperature coal tar atmospheric residue (MCAR,＞350 ℃ fraction) was conducted in a magnetic-stirred autoclave to simulate the situation in real slurry-bed and the influence of reaction pressure, temperature, catalyst, additive and time was investigated. Then the pilot scale test was performed in a slurry-bed hydrocracking pilot plant with a 3 000 mL loop reactor under the optimal conditions determined by the above test. The results show that when the reaction conditions are 425 ℃, initial hydrogen pressure of 9 MPa (reaction pressure of 12.5 MPa), reaction time of 60 min, space velocity of 1.0 h-1, fresh H2 rate of 1 800 L/h , and the dosage of oil soluble Mo-Ni bimetallic catalyst, additive (SDBS) and sulfur of 150 μg?g-1, 200 μg?g-1and 400 μg?g-1, respectively, the total yield of naphtha, diesel and wax oil is 88.26% and vacuum residue is only 7.98% for 24 h operation. Furthermore, the light oil yield per unit of coke formed is up to 48.13%.

PROCESS OPTIMIZATION AND ENERGY SAVING MEASURES OF LUBRICATING BASE OIL PRODUCTION UNITS

2015, 46(8):  24-27. 

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The new "three traditional technologies" units for production of bright stock were built through expansion and reconstruction of old processing units (furfural refining, ketone-benzene dewaxing and clay refining) of SINOPEC Jinan Company. The problems of operation instability, high energy and material consumptions were occurred due to changes of feedstock properties during the start-up. These problems were solved well by technical transformation and adjustment of air cooler process for furfural unit and self-pressure process for three-effect evaporation tower, optimization and adjustment of heat exchange scheme and fresh solvent ratio for ketone-benzene dewaxing unit, stopping clay addition and realizing heat integration of ketone benzene dewaxing unit and clay refining unit. The direct economic benefit of these measures is more than ￥8.042 7 millions/a.

COMMERCIAL APPLICATION OF SGC-1 CATALYST FOR IMPROVING GASOLINE YIELD

2015, 46(8):  28-33. 

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The commercial application of FCC catalyst SGC-1 for improving gasoline yield in the 2nd RFCCU of Sinopec Yanshan Petrochemical Company was presented. The results show that the yield of gasoline increases to 47.57%, 47.05%, and 47.10%, i.e. the growing range of 4.56, 4.04, and 4.09 percentage points, respectively for three solutions of maximizing gasoline yield, maximizing feedstock flow rate, and maximizing blending residue ratio. The selectivity of dry gas, gasoline, and coke are improved, especially the selectivity of gasoline increases significantly. While the yield of total liquid products remained steady. SGC-1 catalyst has significant advances in increasing the yield of gasoline, good feedstock adaptability and dry gas selectivity. It can meet the requirement of improving product distribution of FCC unit.

DEVELOPMENT OF LOW-COST AND ECO-FRIENDLY HYDROCRACKING CATALYST WITHOUT NOx EMISSION

2015, 46(8):  34-39. 

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A clean process was realized by utilizing low cost, clean raw materials and new idea for hydrocracking catalyst production. This technology platform integrated clean peptizing agent, higher pH, low viscosity metal salt solution and modified molecular sieve resistant to acid. No nitrogen compounds were used during the catalyst preparation, resulting in zero emission of NOx and ammonia nitrogen. By optimizing hydrogenation metal species and the way of introduction, the total amount of metals and the bulk density are reduced by 20.0% and 6.5%, respectively, compared with the reference catalyst. The cost of raw materials is reduced by about ￥3.9×104/m3 catalyst, a drop of about 28%. The results of catalytic performance evaluation and stability test show that the new catalysts achieve the similar levels to those prepared by conventional methods and have good stability.

EFFECT OF TITANIA WHISKER MODIFICATION ON HYDRODESULFURIZATION OF Ni-Mo/γ-Al2O3 CATALYST

2015, 46(8):  40-43. 

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Bring titania whisker with pure anatase crystal structure into alumina, the hydrodesulfurization activity of Ni-Mo/γ-Al2O3 catalyst can be increased. The characterizations of Raman spectrum and H2-TPR indicate that titania whisker can weak the interaction between alumina and active components, which favors the active metal molybdenum to form octahedral species, resulting in higher activity of the catalyst. When the content of titania whisker is beyond a certain rang, the catalyst activity is decreased due to the significant reduction of specific surface area.

INFLUENCE OF CALCINATION TEMPERATURE ON PROPERTIES OF UNSUPPORTED MoS2 CATALYSTS

2015, 46(8):  44-48. 

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Unsupported MoS2 were obtained from the decomposition of ammonium tetrathiomolybdate (ATM) at variable temperatures (200-600 ℃) under N2. The effect of calcination temperature on the HDS activity of MoS2 using ammonium tetrathiomolybdate (ATM) as precursor was tested. The structures and properties of the catalysts were investigated by means of BET, XRD, SEM, TEM and XPS. The dibenzothiophene HDS activity was studied in an autoclave reactor. The results indicate that as the calcination temperature rises, the surface area and crysatllinity gradually increase. The characterizations show that the properties of the catalysts are affected by the amount and valence state of S. The optimal calcination temperature for the ATM was 400 ℃, resulting in the highest catalytic activity.

LOW TEMPERATURE HYDROTHERMAL SYNTHESIS OF ZSM-5/ CORDIERITE MONOLITH CATALYST

2015, 46(8):  49-53. 

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A low temperature hydrothermal synthesis method in situ at crystallization temperature 120 ℃ was used to prepare ZSM-5 zeolite coating on cordierite honeycomb ceramic support. The prepared monolith catalysts were characterized by means of X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The firmness of the coating was tested by ultrasonic and thermal shock experiments and the NO oxidation activity of the monolith catalyst at room temperature was investigated. It is found that zeolite coatings with 15 μm thickness (loading 25.8% ZSM-5) are successful synthesized at crystallization temperature of 120 ℃ and that low synthesis temperature favors to the formation of homogeneous distribution of ZSM-5 zeolite on cordierite support. And the thermal shock tests indicate that zeolites coatings synthesized at 120 ℃ show a higher homogeneity and better firmness than that synthesized at 170 ℃. The monolith catalyst synthesized at 120 ℃ also show higher catalytic activity of NO oxidation compared with that synthesized at 170 ℃.

SIMULATION OF AROMATIC EXTRACTION FEEDSTOCK SEPARATION BY DIVIDING-WALL COLUMN

2015, 46(8):  54-60. 

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A new classified lumped model for aromatic extraction feedstock was proposed. And by strict steady-state simulation of DWC and lumped model, the column structure parameters and operation conditions were determined, resulting in the side stream withdraw ratio less than 75%, benzene in the top stream less than 1 %(w), and the yield of C6-C8 fraction in the side stream reaches 99%. Using Aspen Dynamic, a dynamic control structure with three control loops and feedforward controllers was established. The dynamic simulation shows that dividing wall column is a good way to complete the separation of target products; and the temperature control strategy with feedforward can be very good in dealing with feed composition and flow rate fluctuations, the stable time is shorter and the qualities of the products conform to the requirements of the separation.

CORRELATION OF HEAVY OIL HLB VALUE AND ITS MOISTURE INVERTED POINT

2015, 46(8):  61-65. 

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HLB values of eight heavy oil samples of Shengli oilfield were measured by conventional method, and the correlations between the HLB value and the inverted point and the hydroxyl absorption area were studied. The results show that HLB value, inverted point and hydroxyl absorption area of the 8 samples have the same order: xin6xie6>kendong52pai222>shengtuo3pai12xie181>kendong52pai225>xin68xie87>shan56pai11geng9>shan56pai4xie4>caoku126. The reason from the perspective of oil-water interface layer is that the oil-water interface layer is made up of asphaltene aggregates and their chains as well as polar functional groups. The higher HLB values of the oil, the stronger the interacting forces and the emulsifying ability, resulting in higher moisture inverted point and more the functional groups. The quantitative relation shows that for the five ordinary heavy oils, the ratio of the inverted point to the HLB value is 6 and the ratio of the HLB value over the absorption peak area of hydroxyl respectively is 0.1. While for the three super heavy oils, the above two ratios are 5, and 0.015, respectively. It is concluded that using the HLB value to measure heavy oil emulsifying ability is reasonable.

THERMODYNAMIC ANALYSIS OF CYCLOHEXANE DEHYDROGENATION IN MEMBRANE REACTOR

2015, 46(8):  66-70. 

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The cyclohexane dehydrogenation is a model reaction of membrane reactor. The thermodynamic analysis was used to calculate the change of Gibbs free energy, equilibrium constant at different temperatures, and the cyclohexane equilibrium conversion with different removal rates of hydrogen of the reaction system. And the influence of different removal rates of hydrogen on cyclohexane equilibrium conversion was investigated. Further the severity of the reaction and the increasing percentages of equilibrium conversion of cyclohexane with different removal rate of hydrogen were investigated and compared with that of the conventional fixed bed reactor. The potential use of membrane reactor in improving cyclohexane equilibrium conversion of the reversible dehydrogenation reaction was described. It is found that the cyclohexane equilibrium conversion achieved in membrane reactor is higher than that in conventional fixed bed reactor. The results show that membrane reactor can effectively improve the equilibrium conversion of cyclohexane, and reduce the severity of the reaction, indicating its good prospect for industrial applications.

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STUDY ON LUMPED KINETIC MODEL OF HYDROCRACKING IN SLURRY-BED

2015, 46(8):  71-75. 

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Under the conditions of different reaction temperatures and initial hydrogen pressures, the hydrocracking of Karamay atmospheric residue is done in an autoclave in order to simulate the hydrocracking process in slurry-bed. Based on the experimental data and the demand of predicting the yields of light oil products in actual process, a six-lumped kinetic model (gas，gasoline，diesel，gas oil，vacuum residue，coke) of hydrocracking process in slurry-bed is established. The kinetic parameters are determined by the least square method with matlab software and the error is also analyzed. The results show that the model can well predict the yield of each lumped product and the calculation results agree with the experimental value and most of the errors are within 5%.

STUDY ON W-SBA-15 PREPARATION AND ITS ADSORPTIVE DENITRIFICATION PERFORMANCE

2015, 46(8):  76-80. 

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W-SBA-15(x) was synthesized by direct synthesis method using tetraethoxysilane (TEOS) as silica source and Na2WO4 as W source, (x represent the mole ratio of W and Si). The W/SBA-15(x) was prepared by post-synthesis method using prepared SBA-15 and ammonium tungstate solution. The samples were characterized by XRD, BET, and NH3-TPD. Effect of preparation method, WO3 loadings, calcination temperature and time on the performance of adsorptive denitrification was investigated. The results show that the mesoporous structure of SBA-15 can well be remained by both direct synthesis and post-synthesis methods. The ordered crystallinity of W-SBA-15(10) is worse. The denitrification performance of W-SBA-15(20) is better than W/SBA-15(20) and W-SBA-15 (10). The denitrification performance of W-SBA-15(20) is the best when the adsorbent was calcined at 550 ℃ for 6 h. At the adsorption conditions of 140 ℃, 30 min and absorbent/oil ratio of 1:30, the denitrification rate of model oil quinoline solution in dodecane, reaches 66.32% and the saturated absorption capacity is 25.66 mg/g.

ADVANTAGE OF CONTINUOUS LIQUID PHASE DIESEL HYDROGENATION IN ENERGY CONSUMPTION

2015, 46(8):  81-85. 

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The advantages in energy consumption of continuous liquid phase diesel hydrogenation technology developed by SINOPEC with own intellectual property rights were analyzed. The results show that continuous liquid phase diesel hydrogenation technology has an incomparable advantage in low energy consumption over traditional trickle bed process.

ANALYSIS AND APPLICATION OF ENERGY SAVING MEASURES FOR 2.5 Mt/a FCC UNIT

2015, 46(8):  86-89. 

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The measures for optimal energy saving were suggested and applied for a new 2.5 Mt/a FCC unit of Sichuan Petrochemical Co. Ltd.. The measures for energy saving optimized the coke rate, electricity consumption and steam production both in design and operation. The actual energy consumption after 12 months operation reduced significantly compared with the design values. The unit energy consumption of coking, electricity and 4.0 MPa steam production is reduced by 0.080 8 GJ/t, 0.030 1 GJ/t, and 0.041 GJ/t, respectively. The overall energy consumption of the FCC unit decreases by 0.124 GJ/t. The processing cost for the 2.5 Mt/a FCC unit can save ￥7.5 millions/a. Both the energy saving and the economic efficiency are significant.

MODELING VGO HYDROCRACKING PROCESS BY BP-ANN TECHNOLOGY

2015, 46(8):  90-95. 

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The highly complexity of petroleum hydrocracking process results in the application of artificial neural network (ANN) in this field. In this paper a BP-ANN was used to model a VGO hydrocracking unit with a capacity of 2.80 Mt/a. The effect of feed rate, inlet temperatures of reactors, and amount of quench H2 used on product distribution and outlet temperatures of reactors were well predicted by the model. The results show that the model has a higher accuracy, especially in the prediction of temperatures (less than 0.1 ℃ ) and a good ability of reproducibility and generalization ability and that the model is able to guide practical operation.

QUANTITATIVE MEASUREMENT OF WEAK ACID IN COAL TAR BY POTENTIOMETRIC TITRATION

2015, 46(8):  96-100. 

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A method was developed for the quantitative determination of weak organic acids in coal tar by means of potentiometric titration using KOH solution as a titrant and N, N- dimethylformamide as a solvent. The end point of the titration is clearly determined by the inflections of the curves at the equivalence points. Modifications were suggested for GB7304 method, which is unable to get acid number in coal tar sample. The modified method was successfully applied to analyze the coal tar samples. The standard addition recovery is 96%-105%, with RSD’s (n=5) in the range of 0.4%-1.1%.

DETERMINATION OF COMPOSITIONS OF HIGH VISCOSITY POLY ALPHA OLEFINS BY HIGH TEMPERATURE GAS CHROMATOGRAPHY

2015, 46(8):  101-104. 

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The compositions of high viscosity PAO150 were determined by high temperature gas chromatography. The types and polymerization degree of PAO were analyzed by ASTM D7169. The atmospheric pressure boiling points of poly α-olefins with the degree of polymerization of 2-13 in the sample were calculated using CET (Chromatography Equivalent Temperature) method. The results indicate that there is a 1-decene polymer with polymerization degree of 2-16 in the sample and the boiling point of 1-decene polymer is 100 ℃ lower than that of paraffin with same carbon number when the polymerization degree is over 13. The high boiling point components in PAO150 are easy to cracking during the kettle-type distillation process, resulting in reduction of viscosity, viscosity index and relative molecular weight, but bromine index.