Table of Content

12 July 2014, Volume 45 Issue 7

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MOLECULAR-BASED STUDY ON FCC LCO TO LIGHT AROMATICS

Jianhong Gong Gong

2014, 45(7):  1-6. 

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The reaction rule on production of light aromatics (BTXE) of benzene, toluene, xylene and ethylbenzene from hydrotreated LCO by FCC process is studied on molecular level. The results show that the content of heavy monocylic aromatics and FCC reaction conditions are the key factors which influences the yield of BTXE and that the optimal reaction conditions for converting LCO to light aromatics are: moderate hydrotreating severity (hydrogen content 11.0% in hydrotreated LCO), high reaction temperature (over 550 ℃) and middle ratio of catalyst to oil (more than 8) of FCC process. In the range of experimental conditions, the proportion of the apparent cracking reaction of monocyclic aromatic hydrocarbons in hydrotreated LCO is above 73.4%, the condensation reaction is less than 14.7%, and the rest is unconverted monocyclic aromatics. Increasing FCC reaction temperature is favorable for monocyclic aromatics cracking. The once-through yield of light aromatics reaches 14.3% under experimental conditions, about 1/3 of all monocyclic aromatic hydrocarbons in FCC products. It is concluded that the integration of hydrogenation and FCC process is a cost-effective technology to convert inferior LCO to high value BTXE light aromatics.

STUDY ON SYNERGY OF ZEOLITE AND MATRIX AND PROCESS OF HEAVY OIL CRACKING

2014, 45(7):  7-12. 

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The synergy of zeolite and matrix and the VGO cracking routes were studied by a fixed-bed reactor in which ReUSY zeolite and phosphoric acid modified alumina kaolin as matrix were loaded in different layered or mixed packing ways. It is observed that contacting the matrix first for heavy oil results in a higher conversion compared with that of contacting zeolite first. However，neither the molecular sieve nor the matrix along can make the heavy oil convert effectively. This indicates the preliminary cracking functions of the matrix, resulting in synergistic effect of zeolite and matrix. With the mixing degree of zeolite and matrix increase, the conversion and the liquid product yield rises significantly, while the yields of dry gas and coke decrease slightly. The synergy effect of mixing zeolite and matrix was also discussed in view of the hydrogen distribution in dry gas and LPG products. The data obtained in this work well fit the classic cracking mechanism, but existing protolytic cracking path which contributes to a rise in dry gas yield.

STUDY ON HYDROGENATION OF UNSATURATED HYDROCARBON DURING FCC GASOLINE DESULFURIZATION BY S Zorb PROCESS

2014, 45(7):  13-19. 

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The S-Zorb process can reduce the sulfur content of gasoline to less than 10μg/g. However, the hydrogenation reactions of olefins and aromatics occur inevitably during S-Zorb adsorption desulfurization, leading to some octane number loss. In order to optimize the S-Zorb operation, the comparative analysis of the compositions of feed and product of S-Zorb unit of Shanghai Gaoqiao branch was conducted to see the influence of hydrogenation reactions on change of compositions from the point of view of thermodynamics and kinetics. The equilibrium constants and Gibbs free energies at different temperatures were calculated under the normal pressure. And the reaction rate constants were figured out by the 4th order Runge-kutta method.

WET FLUE GAS DENITRIFICATION USING UREA/O3 SOLUTION TECHNOLOGY

2014, 45(7):  20-23. 

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The wet flue gas denitrification test was conducted for the exhaust gas from sorbent desulfurization unit using urea/O3 solution in a packed column. The effect of the experimental parameters of flue gas flow, ozone flow and the stages of ozone oxidation were investigated. The laboratory tests show that the optimum process conditions are 8.6 m3/h of flue gas, 1.5 m3/h of O3 and three stage ozone oxidation. At the above conditions, the removal ratio of NOX using urea/O3 solution technology can reached 99.9%, NOX content in wet flue gas is below 100mg/m3. The results compared with that of urea solution/absorption and supergravity technology indicate that the urea/O3 solution denitrification technology exhibits higher removal efficiency towards NOX in flue gas.

TEST AND ANALYSIS OF FUNGICIDE IN POLYMER FLOODING SYSTEM FOR ENHANCING OIL RECOVERY

2014, 45(7):  24-28. 

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Two kinds of fungicides named Dodecyl dimethyl benzyl ammonium chloride(1227) and isothiazolinone （Kathon 886）were experimentally tested in the lab individually or mixed use in order to investigate their sterilization rate and compatibility with polymer. Test indicates that the mixed usage of two agents with the mass ratio of 1:3 (1227: Kathon 886) achieves better effect than two kinds of fungicides used individually and exhibits a high compatibility with polymer for enhanced oil recovery (EOR), indicating the synergetic effect exists. Under the conditions of no oxygen atmosphere, 53℃ and 90 day aging, the polymer viscosity retention rate is 64.7%. It is concluded that the composite fungicide can be used as a new type of high-effect fungicide in polymer flooding for tertiary oil recovery process.

RESEARCH ON POST-TREATMENT OF FCC CATALYST

2014, 45(7):  29-35. 

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Due to the complexity of present FCC catalyst preparation process, catalyst post-treatment technology was explored. NaY zeolite, pseudo-boehmite, aluminum sol and kaolin were mixed and spray-dried into catalyst microsphere NaY35. The basic properties of the unmodified NaY35 were characterized by XRF、XRD、BET. The NaY35 catalyst was treated by once calcination and then once rare earth ion exchange. The treated NaY35 was used as a starting precursor. The precursor was then treated by three times calcinations and three times ammonium ion exchanges at normal temperature（＜90 ℃）, and two times calcinations and two times ammonium ion exchanges at high temperature（＞90 ℃）, respectively to explore the optimized post-treatment conditions for FCC catalyst．The test results indicate that the Na2O contents in both prepared catalysts are less than 0.3% (wt).

PREPARATION AND APPLICATION OF HYDROUPGRADING CATALYST FOR INFERIOR DIESEL Part I.CATALYST PREPARATION METHOD AND SELECTIVE RING-OPENING TETRALIN

2014, 45(7):  36-41. 

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Tetralin hydroconversion process is a complex reaction consisting of the hydrogenation, dehydrogenation, isomerization, ring-opening, alkyl and transalkylation. Unsupported Ni-Mo-W hydroupgrading catalysts were prepared by three different preparation methods (dry mixing, wet mixing, co-gelling), and tetralin was selected as a model compound to evaluate the hydrogenation and selective ring-opening performance of the catalysts. The results show that the catalyst prepared by co-gelling shows higher hydrogenation conversion of tetralin as well as higher selective ring opening and isomerization performance than the other two catalysts. The wet mixing catalyst has a high hydrogenation selectivity and tetralin conversion rate, but lower in isomerization and ring-opening selectivity. The tetralin conversion rate, the isomerization selectivity and the hydrogenation selectivity are low for the dry mixing catalyst. The single molecule mechanism is mainly followed for tetralin hydrogenation and ring-opening reactions over the co-gelling and wet mixing catalyst, inducing less heavy products and coke. The unsupported Ni-Mo-W hydroupgrading catalyst prepared by co-gelling shows the desired dearomatization performance by selective ring opening.

INFLUENCE OF TITANIUM MODIFICATION ON REDUCTION TEMPERATURE OF SUPPORTED ACTIVE COMPONENTS

2014, 45(7):  42-46. 

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A series of HDS catalysts were prepared using titanium modified cylindrical Al2O3 and SBA 15 SiO2 supports. The active components of Mo, Ni and NiP were loaded on Al2O3 and Ti modified Al2O3 supports. NiP was supported onto the SiO2 and Ti modified SiO2 supports. The influence of titanium modification was investigated on the reduction temperature of the supported active components by temperature programmed reduction (TPR) method. The results show that the titanium modification can lower the reduction temperature of the active components on all catalyst tested. The reduction temperature of NiP on the silica carrier increases significantly compared with that on the alumina carrier. The reason for the lower reduction temperature of active components on the modified catalyst is due to the changes of interaction between active component and carrier by modification of titanium.

STUDY ON EXTRUSION CONDITIONS FOR TRILOBULAR ALUMINA CARRIER

2014, 45(7):  47-51. 

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The influence of extrusion conditions such as water to powder ratio, extruder frequency and material temperature on kneading，extruding, and carrier properties were studied. The results show that the kneading process, carrier properties are directly affected by extrusion conditions. Based on actual production requirement, the optimum extrusion conditions are found as follows: water to powder mass ratio 1.37~1.40, extrusion pressure of 10~15 MPa, extruder frequency of 35 Hz and then 20 Hz at the point where the peptization starts with external circulating cooling water.

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COMMERCIAL APPLICATION OF SINGLE-STAGE, DOUBLE-CATALYST HYDROCRACKING TECHNOLOGY

2014, 45(7):  52-55. 

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A single-Stage, double-catalyst hydrocracking technology (FDC technology) is developed by FRIPP, which converts heavy gas oil to maximum clean diesel. FDC technology has been successfully applied in six commercial units. The commercial results in Jinling branch hydrocracking unit with 1.5 Mt/a as well as Hainan petrochemical co., LTD hydrocracking unit with 1.2 Mt/a show that the middle distillate yield is high (78.99%, 74.87%, respectively) and chemical hydrogen consumption is low（2.31%, 2.15%, respectively）. The FDC technology possesses the properties of simple flow sheet and high LHSV of the single-stage hydrocracking technology and remedy for some shortcomings of single-stage hydrocracking technology such as bad feed adaptability, short running cycle of catalyst and bad quality of hydrocracking product. Moreover, the FDC technology is also featured by good quality of products and flexibility for product slate and low production cost as well.

TECHNICAL TRANSFORMATION AND EFFECTIVENESS FOR REGENERATION FLUE GAS SYSTEM OF RFCCU

2014, 45(7):  56-61. 

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The 3rd RFCCU with a capacity of 2.0 Mt/a in Sinopec Beijing Yanshan Co. ran for more than 1 100 days last operation period. Some issues arose in the flue gas regeneration circuit system at the end of the period. Cracks were found in the lining of the gas flue and local ultra-temperature due to three expansion joints being corroded at the inlet of high temperature heat removal device; the outlet temperature of waste heat boiler was more than 200 ℃(design, 180 ℃) resulting in scaling; One tube bundle exploded and many nicks left; the inlet pipeline of flue gas turbine and the critical nozzle leaked several times. Multiple technical transformations were adopted during the maintenance this year. A large area of linings and five expansion joints were repaired or replaced, material of the inlet pipeline of flue gas turbine was upgraded, and the 4th cyclone separator and a composite phase change heat exchanger were added in the waste heat boiler exit. The operation results reveal that the outlet temperature is reduced to 150 ℃and no ultra-temperature parts in the regeneration flue gas system is observed, resulting in an efficient, economical and long-period operation in RFCCU.

OAPPLICATION OF ONLINE DECOKING TECHNOLOGY IN COKING FURNACE OF 1.2 Mt/a UNIT

2014, 45(7):  62-67. 

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The application of on-line coke cleaning technology in the furnace of 1.2 million t/a delayed coking device in Urumqi petrochemical company is introduced. The problems and countermeasures during the process and the effect were described. The surface temperature of the furnace tube decreases by more than 80 ℃, and 500 m3/h fuel gas consumption are saved due to the application of the technology. The life time of the furnace is effectively prolonged, meeting the three year overhaul period. The main factors affecting coke cleaning are: difference of high and low temperature of tube， rate of heating and cooling temperature，decoking process time, thickness of coke in furnace tube. The changes of gas consumption at constant temperature, surface temperature difference of each furnace tube, and temperature difference between the furnace tube surface and branch outlet can be used as a success criterion for the process.

DEVELOPMENT AND APPLICATION OF DRAG REDUCING AGENT HG-2 SYNTHESIZED BY DOUBLE MATERIAL PRE-POLYMERIZATION METHOD

2014, 45(7):  68-71. 

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Synthesized HG-2 oil drag reducing agent (DRA) by a new controllable pre-polymerization technology was prepared. The polymer average molecular weight is greater than 3.0?106. Performance evaluation, bench test and road test of diesel fuel with 50 mg/L DRA were conducted. Results show that adding 50 mg/L DRA into diesel fuel has no obvious influence on the vehicle performance and the quality can conform to the GB 252-2011 national standard. Field experiment in oil pipeline was conducted. The delivery rate increase of diesel with DRA10 mg/L can be up to 30%. With 8 mg/L DRA, at Reynolds number of 52411, 70940 and 78087, the corresponding delivery rate increase is 26%, 30.2% and 38.6%, respectively.

STUDY ON SELF-REPAIRING PERFORMANCE OF LUBRICANT ADDITIVES

2014, 45(7):  72-76. 

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A phyllosilicate lubricating material was prepared by ball-milling and mixing with traditional additives. The self-repairing performance of lubricant additives in lithium grease was investigated by four-ball friction and wear tester, and the self-repairing effect was evaluated by optical microscope (OM), energy dispersive spectrometer (EDX), and electronic balance. The results were compared with that of the traditional additives and the mechanism was discussed. The results indicate that the composite system of the phyllosilicate and traditional additives exhibits excellent tribological and self-repairing properties. It exhibits the best self-repairing effect at 100N loading, 800 r/min, 60℃, and friction time 80 min. It is concluded that the complex physical chemistry reactions occur between additives and friction surface, resulting in a ceramic-like metal that sinks to the surface defects and forms a protective layer, the so-called self-repairing surface layer.

STUDY ON TRIBOLOGICAL PROPERTIES OF ULTRAFINE SILICON AND Zn COMPOSITE POWDER AS LUBRICATING ADDITIVE

2014, 45(7):  77-81. 

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Lithium base grease was prepared in laboratory. Different composites of ultrafine silicon material (Si-Al type) and Zn powder were designed as the Lithium base grease additives. The four-ball friction tester was used to investigate the influence of different composites on the tribological properties. The results were compared with that of the market additives. The worn surfaces were analyzed by means of optical microscope (OM) and energy dispersive X-ray Detector (EDX). The results show that the tribological properties of the composite powders were more excellent than that of the base grease and market product additives. Compared with base grease, the wear scar diameter and the average friction-coefficient using the composite additive (0.5%Zn/0.5%(Si、Al)) was reduced by 54.97% and 23.62%, respectively, at 588N loading. The analysis of the instant changes of friction-coefficient shows that the amplitude of the friction factor can be effectively reduced by the composite powder, which is helpful to reduce the noise and enhance the steady ability of machine. EDX show that a lubricating film mainly composed of SiO2 and Zn is formed on the worn surface that has notable tribological properties.

INFLUENCE OF ANTI-OXIDANT ON SURFACE HARDENING AND TRIBOLOGY OF OVERBASED CALCIUM SULFONATE COMPLEX GREASE

2014, 45(7):  82-86. 

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The surface hardening of overbased calcium sulfonate complex grease containing different concentrations of anti-oxidant L57 and L135 was studied. The tribology of the grease containing different additives was investigated using MFT-R 4000 reciprocating friction tester after 40 days storage. The worn surface was observed by scanning electron microscope (SEM) and energy spectrum analysis. The results show that antioxidants can postpone the surface hardening of the grease tested and the complex greases containing 2% L57 and 2% L135 have a better tribology performance.

ENERGY-SAVING OPTIMIZATION OF FCC ABSORBTION-STABILIZATION PROCESS

2014, 45(7):  87-90. 

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With the PROII software, the absorption-stabilization process of a new FCC unit was simulated to optimize the energy conservation. The impact of changes of the compressor outlet flow path on absorption-stabilization process parameters and energy consumption was studied to propose measures for process optimization. The simulation results show that the duty of the stripper bottom reboiler and the compressed rich-gas cooler can be reduced greatly using two feeds with different composition and temperature to the stripper. The energy consumption can be reduced by 44.04 MJ/t feed.

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GA-ANN METHOD FOR PREDICTION OF GASOLINE YIELD OF RFCCU

2014, 45(7):  91-96. 

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The system of reaction and generation unit of RFCCU is a highly non-linear and strong coupled operation system and is too hard to be described by traditional model. The combination of the artificial neural network (ANN) with strong nonlinear prediction and self-learning ability and the genetic algorithm (GA) with global optimization ability provides a promising way to solve the problem. The optimal initial weights and threshold value are calculated by GA for the BP neural network first and feeded back to BP model to improve the method for random uncertain choice of initial value and the mapping accuracy. In a practical application of this method for a 2.8 Mt/a MIP device, a 6-11-1 type of BP neural network where the GA is used to optimize the weights and values of the BP network was established using the temperatures of two reactors and two regenerators along with the pressures of the reactor and regenerator as six input variables to predict the output variable gasoline yield. The results show that the predictive gasoline yield by BP neural network without GA has the mean squared error (MSE) of 5.16 while the one with GA optimization has the MSE of 4.92.

DETERMINATION OF PHOSPHORUS CONTENT IN BIOLOGICAL OIL BY ICP-OES

2014, 45(7):  97-101. 

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Dry ashing with auxiliary method and on-line internal standard with direct introduction of organic solvent method are established to determine the P content in biological oil with inductively coupled plasma optical emission spectrometry (ICP-OES). The multicomponent spectral fitting model of phosphorus was used to eliminate the spectral interference of copper. In dry ashing method, the kinds and addition amount of auxiliary were investigated and the organic magnesium was finally selected as the best one. The recovery of phosphorus from 1,2- dioleoyl-sn-glycero-3-phosphocholine is 104%±1%. The limits of detection of two methods were 0.013 ?g/g and 0.264 ?g/g, respectively. Besides, the article points out the shortage of density correction in the ASTM D7111-05 and redressed.

DETERMINATION OF DENSITY OF VISCOUS OIL BY RANDOM WEIGHING –KEROSENE DILUTING AND U-SHAPED OSCILLATING TUBE METHOD

2014, 45(7):  102-106. 

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The kerosene dilution method for determination of density of heavy viscous oil was improved in three aspects. First, random weighed kerosene and heavy viscous oil was mixed, instead of equal volume mixing method. Second, a digital analyzer consisting of a U-shaped oscillating sample tube was used to replace the manual hydrometer method. Finally, a computational formula for viscous oil density determination were programmed and installed into the computer, by which the viscous oil density can be automatically and quickly determined through directly entering four parameters. It is found that the mixture of kerosene and heavy oil closely obey the volume additivity rule and within (1:2) ~ (2:1) mass ratio scope of heavy oil and kerosene, the density of heavy oil can be obtained satisfactorily by the modified method. The standard deviation for three times density determination is less than 0.000 1 g/cm3, parallel to the result of direct oscillating U tube method, but superior to hydrometer method. The modified method is also suitable for heavy crude oil containing bubble.