Table of Content

12 April 2014, Volume 45 Issue 4

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STATUS AND PROGRESS OF COAL GASIFICATION TECHNOLOGY

2014, 45(4):  1-7. 

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Coal gasification technology is the base and key of new coal chemical industry. The correct application of the technology plays a vital role in comprehensive energy efficiency of coal chemical project and running stability. According to the bed classification, this paper describes the technologies of the most widely used fixed-bed and entrained-flow bed and analyzes the characteristics and applicability of pulverized coal, coal-water slurry-flow bed gasifier，solid slag and melten slag fixed-bed gasification technologies. The future development trend of coal gasification technology and some suggestions for technology choice are suggested.

STUDY ON INFLUENCE FACTORS OF DEALUMINATION OF Y ZEOLITE BY CALCINATION

2014, 45(4):  8-13. 

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Dealumination extent affects the catalytic activity and selectivity of zeolite. A series of NH4NaY zeolites were prepared. The effect of calcination temperature, calcination time, Na+ concentration and air humidity on the dealumination extent was analyzed by 27Al small angle MAS NMR experiment. As it turned out, when the NH4NaY sample was calcined in air, the calcination temperature affects the formation of the total extra-framework aluminum and extra-framework aluminum species. When the calcination temperature is high, Na+ content influences the amount and composition of extra-framework aluminum species. Na+ content affects only the amount of extra-framework aluminum when calcination temperature is low. In addition, the calcination time affects dealumination degree, depending on calcination temperature and Na+ content. The calcination time has a complex influence on dealumination degree. The calcination time has no effect on the dealumination degree when calcination temperature is low, while at high calcination temperature, the influence degree reduces as Na+ content increases. The degree of dealumination is also affected by air humidity. The higher the humidity, the more aluminium is removed from the molecular sieve framework.

EFFECT OF CALCIUM ON RESIDUE CONTACT CRACKING CATALYST

2014, 45(4):  14-18. 

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The cracking contact catalyst contaminated by different amount of calcium was studied by BET, NH3-TPD, FT-IR, SEM-EDX. The contaminated catalyst samples were evaluated in a micro-reactor and a fixed-fluidized bed reactor. The results show that both the specific surface area and the pore volume decrease because of pollution. The total acid number and micro-activity of contaminated catalysts decrease even more. However, the pore size distribution suffers no changes. The calcium from calcium naphthenate deposits evenly in the bulk phase of the contact catalysts. The calcium contamination can make Tahe AR FCC product change significantly.

STUDY ON MILD THERMAL CRACKING OF HEAVY OIL

2014, 45(4):  19-22. 

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A series visbreaking experiments were carried out with four types of vacuum residues on LPEC static tester to investigate the effect of reaction temperature and time on the visbreaking ratio and the contents of C7 insolubles in visbroken residue oils. The results indicate that the visbreaking ratio varies with different residue oils under the same operating conditions and that there is a maximum visbreaking ratio as the reaction time increases under the same reaction temperature for the same oil. Under mild reaction conditions, little difference of visbreaking results for different heavy oils is found. However, great changes are observed under severe operating conditions and the visbreaking ratio decreases sharply, showing the stable structures of resins in residue oils are destroyed. The contents of C7 insolubles in visbroken residue oils also vary significantly with reaction temperature and time.

NUMERICAL SIMULATION OF PRESSURE DISTRIBUTION PATTERN IN FCC DISENGAGER

2014, 45(4):  23-26. 

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The pressure distribution inside disengager determines the flow path of the gas and steam, feed speed and the height of material seal leg. To well understand the distribution pattern inside the FCC disengager, a numerical simulation of oil gas flow in a full-size disengager of fluid catalytic cracking unit (FCCU) was conducted by Fluent 6.2 software. The Reynolds stress transport turbulence model (RSM) was used. The commercial disengager of 1.40 Mt/a FCCU was used as the computational geometry model, including the two stage separators and the built-in riser. The simulation results indicate that the space in the disengager can be divided into three regions according to the pressure: high-pressure region inside the primary cyclone separator and riser; medium-pressure region inside the disengager and low-pressure zone inside the secondary cyclone separators. The pressure inside the diplegs of the secondary cyclone separator is the lowest in the disengager, so it is necessary to establish an effective material seal of catalyst particles to balance the negative pressure and lock the air for nesting, or will cause the phenomenon of air leakage.

STUDY OF STORAGE STABILITY OF MODIFIED ASPHALT WITH CRUMB RUBBER

2014, 45(4):  27-30. 

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POR, PPA, vulcanization cross-linking system (sulfur, stabilizer and vulcanization accelerator) and the origin of asphalt stocks all influence the storage stability of modified asphalt. The test results show that the use of TOR and PPA can reduce the softening point difference of segregation of the modified asphalt to a certain extent. There is an optimal value for the dosage of sulfur and stabilizer in the vulcanization system. The compatibility of accelerator has a significant influence on the storage stability of the modified asphalt, and the asphalt stocks from different sources is a decisive factor impacting on the storage stability of the asphalt. The higher aromaticity of matrix asphalt is helpful to the swelling of the crumb rubber in the asphalt and to the desulfurization degradation and cross-liking process, resulting in satisfied modification effect.

EFFECT OF STEAM ACTIVATION ON PORE STRUCTURE OF ALUMINA

2014, 45(4):  31-35. 

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Steam activation is an important way to modify the pore structure of alumina support. Techniques such as XRD, nitrogen adsorption-desorption, mercury porosimetry and nuclear magnetic resonance (NMR) spectrometer were employed to characterize the crystalline phases, surface area, pore size distribution and Al atom chemical shift of these samples. The results show that steam activation can make alumina micropore size larger and macropore size reduction. An activated alumina with larger pore volume, lower bulk density and low surface area can be prepared by the steam treatment. The main reason for the changes of alumina pore structure by steam treatment is the presence of water vapor. The vapor makes the six ligand aluminum atom migrate easily, thus changes the way of the accumulation of Al2O3 particles, resulting in grain growth and structure order degree increase.

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CRACKING PERFORMANCE OF HEAVY FISCHER-TROPSCH SYNTHESIS OIL ON ZEOLITE CATALYSTS

2014, 45(4):  36-40. 

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USY zeolite, Beta zeolite and ZRP zeolite were used for testing the cracking performance of heavy Fischer-Tropsch synthesis oil in a bench-scale fixed-fluidized bed reactor, respectively, emphasizing on the yield and properties of the naphtha product. The results indicate that the highest yield of catalytic naphtha is obtained using the USY zeolite catalyst, the content of iso-paraffins in the catalytic naphtha is as high as 39.87%; the LPG yield of 52.44% and 50.92% are reached over Beta and ZRP zeolite catalysts, respectively with high concentration of propylene. The differences of reaction performance of heavy Fischer-Trosph synthesis oil on the three different zeolite catalysts can be attributed to their different reaction paths. The monomolecular reactions are taken place in a dominant position in the small pores of ZRP zeolite, while in the larger pores of USY zeolite a bimolecular reaction mechanism is operative. In the pores of Beta zeolite, the monomolecular reactions are mainly taken place and the bimolecular reactions can be also occurred in a certain extent, but more than that of ZRP zeolite and less than that of USY zeolite.

STUDY OF PROCESS CHARACTERISTICS OF SKI-400H CATALYST IN DIETHYLBENZENE ISOMERIZATION

2014, 45(4):  41-44. 

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The effect of reaction temperature，pressure, hydrogen/hydrocarbon mole ratio and weight hourly space velocity (WHSV) on the SKI-400H catalyst performance was investigated in a fixed bed. Based on the results, the adjustment of process parameters of its industrial application was conducted. The results show that the catalyst activity is increased with increasing the reaction temperature or pressure or decreasing the hydrogen/hydrocarbon mole ratio and WHSV and the reverse is true for selectivity. Gradually increasing the reaction temperature or pressure can keep the catalyst activity stable in a certain period of operation, but higher temperature can make the selectivity of the catalyst decrease significantly. However, there is a little impact on the selectivity of the catalyst when reaction pressure increases.

INFLUENCE OF V2O5 LOADING ON ISOBUTANE DEHYDROGENATION ON VOx/MgAl2O4 CATALYST

2014, 45(4):  45-49. 

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VOx/MgAl2O4 catalysts with different V2O5 loadings were prepared by the incipient wetness impregnation and their isobutane dehydrogenation activities were investigated. X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier transform infrared (FT-IR) spectroscopy and hydrogen-temperature programmed reduction (H2-TPR) were used to characterize the structure and reducibility of vanadium species on the surface of MgAl2O4. The results show that the isolated and polymeric VO4 species on the surface are present at low vanadium loading of <5% and can be reduced more easily than samples with higher vanadium loading. With increase of V2O5 loadings, mixed magnesium vanadate compounds (Mg3V2O8, Mg2V2O7) appear, which are difficult to reduce by hydrogen. At the optimum V2O5 loading (5%), yield of isobutylene was 31.4% with the corresponding isobutane conversion of about 41.9% at 560 ℃，reaction time 1.5h. Based on the experimental results, it is suggested that low valence Vδ+ (δ<5) species on the surface are the active sites for this reaction..

STUDY ON SULFUR-TRANSFER ADDITIVE FOR SOx REMOVAL AND VANADIUM ANCHORING IN RFCC

2014, 45(4):  50-55. 

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The 0.1Ce/MgAl1.8Fe0.2O4?MgO sulfur-transfer additive was prepared by acid-processed gelatin method. Vanadium trapping capacity of the additive was confirmed through heavy oil micro-reactor evaluation. The comparison of the XRD profile of the V-contaminated FCC catalyst before and after the addition of sulfur-transfer additive proves that the sulfur-transfer additive protect the zeolite in FCC catalyst from being destroyed and can restrain the generation of Mullite at the same time. The DTA results of the mixture of V2O5 and sulfur-transfer show that it is the components in sulfur-transfer additive such as MgO and CeO2 that form the stable new compounds such as Mg3(VO4) and Ce(VO4), which protect the FCC catalyst zeolite from damage. The influence of V2O5 content on DeSOx activity and the crystalline structure was also studied. It is found that the DeSOx activity and renewable performance remains stable and the crystalline phases intact when the content of V2O5 is under 5%, while its surface area decreased and pore structure is changed slightly if the V2O5 is above 5%.

COMMERCIAL APPLICATION OF TWO-STAGE HYDROGENATION FOR PRODUCING AROMATIC EXTRACTION MATERIALS FROM PYROLYSIS NAPHTHA

2014, 45(4):  56-59. 

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catalytic pyrolysis cracking (CPP) naphtha contains a large quantity of mono-olefin, di-olefin, alkenyl aromatic, indene and other unsaturated hydrocarbons as well as sulfur, nitrogen, oxygen in organic compound. It can result in unstable cracking naphtha, which tends to form condensate like resin and impurities. However, CPP naphtha can be treated by two stage hydrogenation process to produce on-specified aromatic extraction raw material. The first time commercial test shows that the two stage hydrogenation technology for producing aromatic extraction materials from pyrolysis naphtha is reliable and stable.

TECHNIQUE-ECONOMICS ANALYSIS OF FCC FLUE GAS DESULFURIZATION SCHEMES

2014, 45(4):  60-63. 

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FCCU flue gas desulfurization process is now in a boom period. There are sulfur transfer additive and wet flue gas desulfurization (WFGD) that can be selectively considered for a 1.80 Mt/a catalytic cracking unit with two risers for prolific propylene. The cost of additives, recycling product and alkali waste treatment, equipment investment, operating cost and occupied areas of schemes were compared comprehensively. The results show that under the present environmental requirements, the scheme adopting sulfur transfer additive is more economical than the WFGD when the SOx content in flue gas to be treated is less than 1000 mg/Nm3, while in the case of more than 1000 mg/Nm3 SOx, the combination of above two schemes or only the WFGD may well be adopted.

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PREPARATION OF ENVIRONMENTAL-FRIENDLY AROMATIC OIL BY HYDROGENATION-EXTRACTION COMBINATION PROCESS

2014, 45(4):  64-67. 

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Using the extracted FCC slurry oil as raw material, the environmental-friendly aromatic oil was produced by hydrogenation-extraction combination process. The selective hydrogenation of the slurry feed was conducted under the optimal conditions: 300 ℃, hydrogen pressure 6.0 MPa, reaction time 6 h in an autoclave, then the product was hydrotreated again under the same conditions. The mass fraction of PCA is decreased from 56.28% in raw oil to 7.86% in hydrotreated product and the liquid yield is 94.10%. Further reduction of PCA is completed by the extraction process. Under the conditions of the extraction temperature 50 ℃, extractant to oil ratio 2:1, complex solvent (A: B) ratio 1:1, extraction time 15 min, the content of PCA is decreased to 2.40% with the extracted liquid yield 85.30%. The quality of the product is improved greatly and close to the VIVATEC500.

PRACTICE OF REVAMPING DIESEL HYDROTREATING UNIT FOR NAPHTHA HYDROTREATING

2014, 45(4):  68-72. 

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The operation of diesel hydrogenation unit expansion revamping for hydroprocessing the mixed feed of coker gasoline (naphtha) and non-aromatic naphtha were introduced. Problems during the operation and measures were discussed and proposed. The practices indicate that at the conditions of high separator pressure 3.40 MPa, reaction temperature of R1/R2 222℃/266~170℃，LHSV1.85 h-1，the sulfur content in the refined naphtha is less than 200 ?g/g, meeting the requirements for ethylene production and large load production as well. All transformation reaction, fractionation and desulfurization system can keep running smoothly. Some of the issues affecting the smooth operation of the device and product quality, after eliminating defects and operational adjustment, are basically resolved.

APPLICATION OF HIGH TEMPERATURE CORROSIVE INHIBITOR AT HIGH TEMPERATURE POSITIONS OF DISTILLATION UNIT

2014, 45(4):  73-76. 

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Naphthenic acid corrosion seriously affects the smooth operation of devices and even leads to major incidents. A high temperature corrosive inhibitor CK356N2C is used at five high temperature places of the distillation unit in SINOPEC Yanshan Co. to lighten corrosion. The results are evaluated by lateral line hydrogen flux detection and iron content analysis. The evaluation shows that the high temperature corrosive inhibitor plays a positive role in the inhibition of naphthenic acid corrosion at high-temperature parts: the hydrogen flux drops by 67.34%～88.82% and the iron content of the second and third vacuum side-stream is decreased to 0.357 μg/g and 0.417 μg/g, respectively, indicating the functions of the corrosion inhibitor.

INDUSTRIAL SIDE-LINE TEST OF COMPLEXING DECALCIFYING AGENT FOR CRUDE OIL DECALCIFICATION

2014, 45(4):  77-81. 

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The 1.5 m3/h crude from 2Mt/a No.2 atmospheric and vacuum distillation unit in Karamay petrochemical co. was fed into in a self-made small scale electric desalting device for decalcification test with own developed complexing decalcifying agent. The results show that for low calcium content crude oil, 6% water injection and dosage of decalcifying agent 60ppm, using a structured channel mixer followed by tube packing mixer, can get the removal rate of Ca, Fe and Mg of 71.5%～78.2%，32.3%～45.5% and 30.0%～38.2%，respectively. The water content in decalcified oil is less than 0.3%. The discharged water meets the quality requirements for industrial use.

PROBLEMS DURING END POINT ADJUSTMENT OF DELAYED COKING GASOLINE AND COUNTERMEASURES

2014, 45(4):  82-84. 

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The operation experience of adjusting end-point of delayed coking gasoline of 1.5Mt/a delayed coking unit in Karamay Petrochemical Corp is summarized. The issues during the adjustment are discussed in terms of diesel system overloading, top circulating reflux pump exhausting and salt deposition on column trays. It is proved that the above issues could be handled appropriately by optimizing diesel process flowsheet, adding top circulating water sump，and cleaning tray periodically. As a result, the coking gasoline end point could be controlled under 180 ℃ and used as the feed for reforming. The diesel yield increases by 3.45% as well as higher diesel to gasoline ratio.

STUDY ON TRIBOLOGICAL PERFORMANCE OF COMPLEXING FRICTION MODIFIER IN DIESEL ENGINE OIL

2014, 45(4):  85-89. 

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The four-ball friction and wear tester was used to investigate the tribological properties of complexing friction modifiers of molybdenum dialkyl dithiophosphate and nitrogen-molybdenum complex, phosphate, N-containing borate ester in CF-4 15W-40 diesel engine oil. A uniform design method was used to design the test. The partial least squares quadratic polynomial regression method was introduced to establish the regression model of multi-independent variables on the multi-dependent variables. The relationship between independent variables of temperature and additives content and the dependent variables of friction coefficients at low, medium and high load and wear scar diameter (WSD) were created, resulting in the optimum formula of the complexing friction modifier, which was verified by experiment. The results show that the optimum composition of complexing friction modifier is consist of molybdenum dialkyl dithiophosphate and nitrogen-molybdenum complex, phosphate, N-containing borate estethe as 0.779 9%，1.200 0%，0.662 9%, respectively. The optimum formula can effectively reduce the friction and wear: more than 43% reduction of the friction coefficient and 47% decrease of the WSD.

STUDY OF COMPOSITION OF HAZE IN 120BS BRIGHT OIL

2014, 45(4):  90-92. 

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The haze in 120BS bright oil was separated by solvent method. The structure and composition of the haze was characterized by average molecular mass, simulated distillation, gas chromatography (GC) and nuclear resonance (13C-NMR). The results show that the haze does not affect the properties of the bright oil, but affect its appearance seriously, although the content of haze is 0.05% only. The haze is characterized by its higher average molecular mass and higher simulated distillation temperature than the de-hazed oil and is mainly composed of n-alkanes, iso-paraffins, and cycloalkanes. Among of them, 20.2% is high carbon n-alkanes and the rest is i-paraffins and cycloalkanes with lower levels of isomers. All these components have higher freezing point. However, there are some n-alkanes and cycloalkanes with somewhat lower freezing point and low level isomerization in the haze. At the industry level, the haze is actually considered to be composed of a mixture of microcrystal wax and foots oil.