Table of Content

12 March 2014, Volume 45 Issue 3

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INVESTIGATION ON INFLUENCE FACTORS OF METHANE FORMATION IN NAPHTHA CATALYTIC CRACKING

2014, 45(3):  1-5. 

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The difference of CH4 yields in catalytic cracking and thermal cracking of naphtha were investigated. The influence of operating parameters, micro-activity of catalyst and hydrocarbon structures on the CH4 yields and selectivities was explored. The results indicate that catalytic cracking reaction has a larger contribution to methane formation in range of 600℃ to 700℃, in which the stronger Br?nsted acidic sites play a key role. Paraffinic hydrocarbons are apt to produce more methane and the protolytic cracking tend to take place on C–C bond or C–H bond adjacent to C2 carbon atom in the carbon chain. Among the factors, the cracking temperature and reaction time are the most important. In order to make balance between conversion of feed and CH4 selectivity, the optimized measures of suitable reaction temperature, high catalyst-to-oil ratio and short residence time are proposed.

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EFFECT OF OPERATING PARAMETERS ON LOW CARBON OLEFIN SELECTIVITY

2014, 45(3):  6-10. 

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Low carbon olefins and distillates are produced separately by two FCC units in Jingmen petrochemical company. In order to obtain high selectivity for low carbon olefins and liquid product of distillates at the same time respectively by the two units, the operation parameters were examined, including reaction time, ratio of catalyst to oil, and regeneration temperature. The results show that these parameters have different effect on the selectivity and distillates yield. As the reaction time prolonged, thermal cracking will increase, resulting in more dry gas and H2. Increasing the ratio of catalyst to oil is the better way to keep the propylene yield and increase the total liquid yield. The higher initial oil-catalyst contact temperature is good for low carbon olefins formation. In case of high yields of gasoline and diesel needed, the regeneration temperature must be optimized.

INFLUENCE OF DISPERSION OF ASPHALTENE IN DECALIN ON HYDROTREATING REACTION

2014, 45(3):  11-13. 

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Asphaltene exists in residue in form of large molecular aggregates and it is difficult to diffuse and react in catalyst microporous. Tahe atmosphere residue was used as test material to see the effect of stirring on hydrotreatment results. It is found that by addition of a constant-temperature stirring process at 373K for 1h before the residue hydro-treatment, the diffusibility of asphaltene in catalyst microporous is improved due to the depolymerization and dispersion of decalin for asphaltene. Compared with the results without stirring, the stirring process can make asphaltene conversion increase by 15%, the coke yield decrease by 2.5%, and the hydrotreated residue amount also decreases. The four components of hydrotreated residue undergo a significant change: the saturate, aromatic, and resin are increased. The removal of sulfur and nitrogen is improved to different degrees. It is demonstrated that the structure state of asphaltene is changed by stirring and that the addition of the stirring step is beneficial to hydroconversion of asphaltene.

CRYSTAL PRECIPITATION LAW OF BIODIESEL AT LOW TEMPERATURES

2014, 45(3):  14-17. 

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Based on the viscosity-temperature curves of soybean oil, waste oil and peanut oil biodiesel, the cloud points of biodiesels were obtained. The amount and composition of precipitated crystals of biodiesels at different temperatures were measured by high speed centrifugation and gas chromatography (GC). It is found that the solid filtrated from the biodiesel is not a pure crystal, but a mixed one mainly composed of saturated fatty acid methyl esters(FAMEs). The amount of FAMEs with high carbon number is more than that with low carbon number. The higher content of saturated fatty acid methyl ester, the higher cloud point and viscosity and the more crystal precipitation as well. The diesel will exhibit worse cold flow properties.

THERMAL STABILITY OF Ce MODIFIED γ-Al2O3 SUPPORT UNDER PULSE ELECTROMAGNETIC FIELD

2014, 45(3):  18-21. 

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Ce modified γ-Al2O3 support samples were prepared by sol-gel method with and without the presence of a pulse electromagnetic field (PEMF), respectively. The physical properties and thermal stabilities of the samples at different pulse voltage were characterized by N2 physisorption, scanning electron microscope, IR spectroscopy and X-ray diffraction techniques. Results show that the specific pore volume and specific surface area of Ce modified γ-Al2O3 sample at 300 V increase by 19.50% and 18.45%, respectively, compared with sample without PEMF treatment. Moreover, the amount of hydroxyl group covered on the surface of γ-Al2O3 increases resulting from evenly dispersed CeO2 and the high temperature thermal stability of samples with PEMF treatment is improved accordingly.

EFFECT OF DIFFERENT ANTIOXIDANT ON THERMAL STABILITY OF SULFOLANE

2014, 45(3):  22-24. 

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Four kinds of antioxidants were selected to investigate the effect on the thermal stability of sulfolane. The quantity of sulfur dioxide release was taken as the comparison index. The results show that all antioxidants chosen are effective for improving the thermal stability of sulfolane and that the influence order of the four antioxidants on the thermal stability of sulfolane is phenolic antioxidant ＞ amine antioxidant ＞ sulfur containing antioxidant ＞ copper containing antioxidant. The phenolic antioxidant has the best effect when the addition amount of this antioxidant is 0.12g.

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EFFECT OF CRACKING DEPTH OF HEAVY OIL MILD THERMAL-CRACKING IN DELAYED COKING PROCESS

2014, 45(3):  25-29. 

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As the feedstocks of delayed coker become heavier and inferior, there are more challenges for coker unit，such as higher liquid product yield , long-term and safe operation, environmental protection and capacity of the unit. A new process named ADCP which integrates a mild thermal cracking stage with a deep thermal cracking stage with one furnace in a coking unit is realized by LPEC for higher liquid product yield. Studies were conducted in LPEC pilot plant with visbreaking, delayed coking and continuous distillation to investigate the effect of heavy oil mild thermal cracking depth on the properties and compositions of coking products. The results show that the yields of liquid products are improved by 0.48, 0.97 and 1.71 percent, respectively when visbreaking ratios of heavy oil are 33.03, 52.43 and 78.21 percent. The yields of light liquid products are increased by 1.04, 1.11 and 2.19 percent, respectively, compared with that of the traditional process. The improvement in light oil yields is mainly manifested in yield increase of the diesel fraction. However, the properties of ADCP products are almost the same as the ones of traditional process products, so the new process has no negative effects on down-stream processes.

EFFECT OF H2S AND NH3 ON HETEROATOMIC REMOVAL BY HYDROGENATION

2014, 45(3):  30-34. 

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Single and Two stage hydrotreating tests were performed in pilot plant using high sulfur Middle-East residue. The results indicate that HDS is inhibited by H2S and NH3 for their competitive adsorption. The higher H2S and NH3 contents in reaction atmosphere are not in favor of residue HDS; However, HDN can be promoted by H2S as it promotes the C-N bond breaking reaction. More H2S content is also favorable for residue HDM.

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STUDY ON MIP-LTG PROCESS

2014, 45(3):  35-39. 

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The investigation of a MIP-LTG process for enhancing high octane gasoline production by cracking heavy diesel fraction was conducted in a continuous catalytic cracking unit. The test results show that a high yield of good quality gasoline can be obtained at high conversion and propylene yield in appropriate reaction temperature range. By increasing catalyst to oil ratio, the conversion, liquefied gas yield, gasoline yield and octane number are all increased, while more dry gas and coke is observed as well. The properties of feed have a critical influence on the product distribution and properties. The higher aromatic content, in particular, the higher monocyclic aromatic content in the feed, the higher content of aromatics in the gasoline product, and the higher gasoline octane.

SELECTION OF REFINING CONFIGURATION FOR MAXIMIZING CLEAN GASOLINE PRODUCTION

2014, 45(3):  40-45. 

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The grass-root large-scale refinery with a capacity of 12.0 Mt/a processing Saudi Arab medium crude is studied for maximizing clean gasoline production by PIMS linear programming mode. Two typical refining configurations of Case 1 (the combination of ARDS+RFCC) and Case 2(the combination of RDS+RFCC and VGO HCR) are compared. The results show that the Case 1 with 4.4744 Mt/a gasoline production is better than the Case 2 with 4.0516Mt/a gasoline. Based on Case 1 selected, more gasoline with the production of 0.718 Mt/a can be further increased by FCC light fraction etherification, LPG alkylation and ethylbenzene synthesis of benzene and thin ethylene in RFCC. And clean gasoline product meeting the GB17930—2013 standard can be obtained by optimization of blending ratio of the gasoline pool components.

COMMERCIAL APPLICATION OF LURGI MTP TECHNOLOGY

2014, 45(3):  46-50. 

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The characteristics and commercial application of Lurgi`s methanol-to-propylene (MTP) technology in Shenhua Ningxia Co, Ltd. was introduced. Through the technical improvement and optimization, some of the problems in this process, such as the cavitation of chilling water pump, the over standard Na+ amount in process steam and water in propylene were solved, resulting in improved capacity of the process steam tower and full load operation of the MTP device. But there are still some problems in the process: the complex structure of MTP reactors, the uneven distribution of materials, and the insufficient capacity of the process steam tower. The industrial operation results show that the propylene yield is about 1.5 %~9.8 % lower than the designed value, while the yields of liquefied petroleum gas and fuel gas are higher. Gasoline fraction obtained from Lurgi’s MTP reaction is characterized by low normal alkane and high aromatic content. The composition of the MTP gasoline is quite different from that of the conventional FCC gasoline. The total life of MTP catalyst is less than 8 000 h, and its regeneration cycles is only about 640-700 h.

EFFECT OF SILICON ON REFORMING CATALYST PERFORMANCE

2014, 45(3):  51-54. 

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This paper described the influence of Si addition in different ways on the performance of reforming catalysts. Introduction of Si-containing molecular sieve in catalysts increases the cracking activity and coking rate, and lowers the selectivity. The experiment find that the addition of Si in carrier preparation leads to the reduction of specific surface area and selectivity of the catalysts and higher coking rate and that after contaminated by Si during reforming reaction, the Cl-keeping capacity becomes poor and the catalyst activity is dropped as well. Si poisoning are irreversible and catalyst activity cannot be recovered through conventional regeneration method.

RESEARCH AND COMMERCIAL APPLICATION OF HYDROCRACKING CATALYST FC-20

2014, 45(3):  55-61. 

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To well understand the new generation hydrocracking catalyst FC-20 with high selectivity of middle distillates, the tests in pilot plant were conducted using several kinds of feedstocks under different pressures, different conversion depths with different diesel upgrading scheme. The test results show that the catalyst FC-20 is characterized by suitable cracking activity, high hydroisomerization activity, good temperature sensitivity and strong ability to preferentially crack and isomerize wax components in feed. The catalyst also has a good flexibility to product scheme and wide adaptability to feeds, which could be used to produce premium chemical naphtha, No.3 jet fuel, clean diesel with low solidification and high cetane number, and low pour point lube base oil feed. The results of commercial application indicate that catalyst FC-20 can upgrade the poor quality diesel and improve the low temperature fluid performance.

COMMERCIAL APPLICATION OF THE THIRD GENERATION RHT SERIES CATALYSTS IN RDS UNIT

2014, 45(3):  62-66. 

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The application results of the second and third generation RHT series catalysts in the 4th -6th run of the RDS unit in Hainan Refining & Chemcial Co., Ltd. were introduced. The third generation RHT series catalysts show its good abilities and stability to remove impurities and carbon residues during 412-day long-term operation. Comparison the results in the fourth, fifth and sixth cycle with the imported catalysts reveals the better activity and stability of the second generation and third generation RHT series residue hydrotreating catalysts.

PERFORMANCE ANALYSIS OF PS-VI CONTINUOUS REFORMING CATALYST AT SOR AND EOR

2014, 45(3):  67-70. 

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This article expounds the commercial application of PS-VI catalyst (RC011), developed by Research Institute of Petroleum Processing, in the 0.8 Mt/a continuous reforming unit (CRU) of SINOPEC Zhenhai Refining and Chemical Company (ZRCC). In order to examine if the activity and selectivity has changed, the calibrations of the unit are conducted at its SOR and EOR stages. It is discovered that after running for 541 operation cycles, the surface area of the catalyst decreases from 187 m2/g at SOR to 143 m2/g at EOR and iron content increases form 280 ?g/g at SOR to 2 400 ?g/g at EOR, resulting in decrease of the catalyst activity by 4.1℃ and the selectivity of the stabilized gasoline, aromatics and H2 yield decreases 1.77％, 1.13％ and 0.2%, respectively. These changes result in the benefit of the device falling 28.136 million yuan/a. It is suggested that the replacement of the catalyst be once every 4 years to keep pace with the factory overhaul cycle every four-years.

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RESEARCH AND OPTIMIZATION OF NAPHTHENIC LUBE BASE OIL MANUFACTURE PROCESS

2014, 45(3):  71-75. 

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After comparison of the combined processes of hydrotreating, hydrofinishing with one of three kinds of dewaxing processes: selective dewaxing, hydrodewaxing, and hydroisodewaxing in pilot plant, the hydrotreating-hydrodewaxing-hydrofinishing cascaded process with obvious advantages is chosen to produce naphthenic base oil from Suizhong-361 VGOs. The reaction conditions in each stage are determined by process simulation, respectively. The hydrotreating process conditions are：H2/Oil ratio of 820, space velocity of 0.5 h-1, total pressure of 16 MPa, WABT of 365—390 ℃; the hydrodewaxing process needs the conditions as follows: H2/Oil ratio of 580, space velocity of 3.0 h-1, total pressure of 15.5 MPa and WABT of 370—380 ℃; while for the hydrofinishing, space velocity of 1.5 h-1and WABT of 250 ℃ are needed. Besides, the steam stripping desulfurization is replaced by high pressure hydrogen stripping. The side-draw of kerosene and light diesel and the heat transfer process are all optimized to lower the investment and operation cost.

RESEARCH ON LSXPT-1 TYPE DUAL-DIRECTION LIQUID SPRAY NOZZLE

2014, 45(3):  76-79. 

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The distribution performance, liquid drop size, the inlet pressure change and entrainment of the LSXPT-1 type dual direction liquid spray nozzle were studied in air-H2O system by synthetic glass tower (ID1000mm) device. The results indicate that its distribution non-uniformity coefficient are between 0.031-0.040, 40% lower than that of the conventional trough-type liquid distributor as well as the buffer sedimentation-type liquid distributor, exhibiting excellent distribution performance. With increase of liquid flow rate, the nozzle inlet pressure increases. The pressure can reach to 0.04-0.66 MPa and the liquid drop size from dual-direction liquid spray nozzle is between 1 975-2 350 μm in the flow rate range of 2.15-9.62 m3/h, much higher than the size of 400-700 μm, required for the liquid droplet settling at gas-liquid flow in turbulent state when gas velocity between 3.0-4.0 m/s. Results show that the entrainment quantity is still less than 7% when the empty tower velocity is as high as 4m/s. Thus the new nozzle can increase the tower’s upper limit of operating gas velocity and the processing capacity.

EFFECT OF WASTEWATER SHOCK ON REFINERY HIGH CONCENTRATION WASTEWATER TREATMENT SYSTEM

2014, 45(3):  80-83. 

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Keeping the stable quality of high concentrated wastewater is the key to reach the discharge standards for refinery wastewater. The operation results of high pollutant wastewater treatment system indicate that the wastewater shock has a severe influence on alkaline residue wet-air oxidation process and oil-removing process, resulting in more phenol, sulfide and oil than design requirement in treated wastewater and low dissolved oxygen in bio-chemical process under the wastewater shock conditions. It becomes the bottleneck for effluent to meet the discharge standards. Solutions were put forward to solve the problems.

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ANALYSIS OF HYDROCARBON AND NON- HYDROCARBON COMPOSITION IN COKER DIESEL OF FCVR AND ITS SFEF FRACTIONS

2014, 45(3):  84-89. 

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The hydrocarbon and non-hydrocarbon compositions of coker diesel of Xingjiang Fengcheng vacuum residue (FCVR) and supercritical fluid extraction narrow fractions (SFEF) were analyzed by GC, GC-MS, GC-SCD and GC-NCD methods. The results show that the composition and distribution of hydrocarbon and non-hydrocarbon are affected directly by properties of feeds. With the fractions getting heavier, the content of sulfur and nitrogen compounds gets higher, and the types of hydrocarbon and non-hydrocarbon compounds become more complex. The content of saturated hydrocarbon in coker diesels is higher than that of aromatics and so as the cycloalkanes compared with that of alkane. The contents of aromatics in diesels increase and the saturated hydrocarbon is just the opposite with the fractions getting heavier. Sulfides in diesels are mainly benzothiophenes and dibenzothiophenes, while alkaline quinolines and benzoquinolines, neutral indoles and carbazoles are main N-containing components.

ESTABLISHMENT OF RAPID EVALUATION METHOD FOR OXIDATION STABILITY OF TRANSFORMER OILS

2014, 45(3):  90-96. 

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The transformer oil oxidation stability was tested by two methods of classical NB/SH/T 0811 and ASTM D2112 Rotating Bomb Oxidation, different results were observed. The inconsistency is caused by high temperature (140℃) and lower oxygen pressure (620KPa) of the RBOT method. At the optimized conditions of 120℃ and 1500KPa, and taking the time at which the quick reduction of oxygen pressure occurs as the end point, the consistency of the two methods is obtained. Based on these experiments, an easy and reliable method as early assisted method for evaluating oxidation stability of transformer oil is established with best resolving power and repeatability.