Table of Content

12 March 2013, Volume 44 Issue 3

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THE PREPARATION OF PROPYLENE OXIDE BY PROPYLENE EPOXIDATION WITH HYDROGEN PEROXIDE IN 1.0 kt/a PILOT PLANT

2013, 44(3):  1-5. 

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The environmental friendly preparation process of propylene oxide (PO) by propylene epoxidation with hydrogen peroxide was studied. Based on the results of basic research, laboratory test and side-line testing, a 1.0 kt/a pilot plant was built for PO preparation by epoxidation of propylene with hydrogen peroxide. Factors influencing the conversion of hydrogen peroxide and PO selectivity were investigated on pilot plant, using HPO-1 catalyst containing modified hollow titanium silicalite molecular sieve. The process conditions of pilot plant test were confirmed, in which the reaction temperature is 30—70 ℃, the WHSV of hydrogen peroxide is 0.12—1.20 h-1, the molar ratios of methanol to hydrogen peroxide and propylene to hydrogen peroxide are 5—25 and 1.2—2.5, respectively. Running under such conditions for more than 6 000 hours, the decrease of catalyst activity is nonsignificant, the conversion of hydrogen peroxide is 96—99% and the PO selectivity is 96—98%. By separating with dual azeotropic distillation process and purification, the purity of PO product is more than 99.97%.

DEVELOPMENT AND COMMERCIAL APPLICATION OF MIP-DCR PROCESS

2013, 44(3):  6-11. 

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Based on studying the reaction chemistry of catalytic cracking, MIP-DCR process was developed to reduce the dry gas and coke yields in FCC process theoretically. The principles of development were discussed and some possible operation modes of MIP-DCR process were explored on a small scale of experimental unit. It was found that operating under higher catalyst activity and lower catalyst to oil ratio, less dry gas and coke were produced. Results of commercial application show that in MIP-DCR process the reactions of protonation cracking and thermal cracking are suppressed somewhat, thus the yields of dry gas and coke reduce by 15.58% and 4.10%, respectively. At the same time, the yields of LPG and gasoline increase slightly, the energy consumption is lower too. Moreover, in MIP-DCR technology, since it is not restricted by the unit heat balance, taking catalyst to oil ratio as an independence variable, more flexible operation modes can be adopted. Besides, the blending efficiency of regeneration catalysts with different temperatures in a pre-lift mixer was modeled by CFD software as well.

A COMPARISON STUDY OF HEAVY CRUDE DELAYED COKING AND VACUUM RESIDUE DELAYED COKING

2013, 44(3):  12-17. 

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In some refining enterprises, using delayed coking to process heavy crude directly becomes the first choice of processing inferior crude. The features of heavy crude delayed coking are introduced in this paper, and the delayed coking processes of processing heavy crude and conventional vacuum residue (VR) are compared from the aspects of corrosion type, product distribution, operation of heating furnace and coke drum, as well as startup procedure. It can be seen that in VR delayed coking, high temperature sulfur corrosion and low temperature H2S corrosion are the main corrosion types; for heavy crude delayed coking, naphthenic acid corrosion is the dominant one. Under the same recycle ratio, in heavy crude delayed coking the total liquid yield is higher, especially middle distillate; yet for VR delayed coking, the yields of coke and rich gas are higher, total liquid yield is relatively lower. The coking tendency in heating furnace of heavy crude delayed coking is much lower than that of VR delayed coking, besides, the gas linear velocity in coke drum of the former is also slightly lower than that of the latter.

APPLICATION OF WINDMILL STYLE PHYSICAL SEPARATION TECHNOLOGY IN CCR UNIT FOR GRADING CATALYST

2013, 44(3):  18-20. 

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Windmill style physical separation technology was applied at the CCR unit of SINOPEC Jinling Company for grading withdrawn CCR catalyst based on catalyst density varied with coke content. Non-porous beads and fine catalyst particles were separated from normal catalyst. After separation, the maximum coke content of the usable catalyst was 4.5%, which is lower than the control index of less than 6%. The low coke catalyst beads were reused in CCR unit and the operation results showed that the reuse catalyst not only well met the requirements of reaction and regeneration, but also shortened the black burning time during the start-up of regeneration system.

THERMODYNAMIC ANALYSIS AND EXPERIMENTAL STUDY OF PENTANE ISOMERIZATION TO ISOPENTANE

2013, 44(3):  21-25. 

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In this paper, thermodynamic analysis of pentane isomerization to isopentane was carried out in detail. Thermodynamic data, including standard molar enthalpy change, standard molar Gibbs free energy change and standard equilibrium constant at various temperatures were calculated. The effects of temperature, pressure, and molar ratio of hydrogen to hydrocarbon (H2/HC) on the isomerization rate of pentane were discussed. It is found that the isomerization of pentane is an exothermic reaction, lower temperature favors the proceeding of reaction and the cracking reactions of pentane are suppressed as well. Hydrogen partial pressure has significant effect on the conversion and selectivity of pentane isomerization, overhigh hydrogen partial pressure leads to decrease of pentane conversion. The experimental study on isomerization of pentane to isopentane was conducted in a fixed-bed reactor, using RISO C5/C6 paraffin isomerization catalyst developed by Research Institute of Petroleum Processing. Results show that the experimental data agree well with the thermodynamic calculation results. However, reaction temperature, pressure and H2/HC ratio are the main factors affecting the isomerization process, it is essential to optimize these parameters for an optimum utilization of catalyst.

STUDY ON THE REMOVAL OF SULFUR COMPOUNDS IN GASOLINE BY SELECTIVE ADSORPTIVE DESULFURIZATION PROCESS

2013, 44(3):  26-31. 

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The performance of selective adsorptive desulfurization of FCC gasoline and HDS gasoline over a series of adsorbents, including microporous and mesoporous materials, was investigated using microcoulomb analysis and GC-SCD technique, focusing on the removal selectivity of sulfur compounds in gasoline. Results indicate that the interaction modes between adsorbents and the sulfur compounds in model oil and gasoline sample are varied. Among the tested adsorbents, adsorbent containing CeY exhibits good sulfur removal effect to both FCC gasoline and HDS gasoline. Other adsorbents for the removal of thiophenes, particular for the small alkylthiophene molecules, neither microporous nor mecroporous adsorbents are effective. For an individual adsorbent, the compositions of sulfur compounds in gasoline have great impact on the sulfur removal rate.

EFFECT OF CH4/N2 ATMOSPHERE ON THE YIELD AND COMPOSITION OF GAS FROM HEAVY OIL THERMOLYSIS

2013, 44(3):  32-35. 

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In delayed coking process, water vapor is injected into the heater as a dilution medium to suppress coke formation, yet sour water pollution is generated, now dry gas is proposed to use as an alternative dilution medium to eliminate the sour water pollution. In order to investigate the effect of dry gas on the yield and compositions of gas formed by thermolysis, thermal reaction experiments are conducted under the atmosphere of CH4 and N2 using vacuum residues from Jinling, Jinan and Qingdao as feeds, the gas yields and compositions are measured. Results indicate that under the same reaction conditions, compared with in N2 atmosphere the gas yield in CH4 atmosphere is lower and the volume fraction of methane in cracking gas is 1-2 percentage point lower. Furthermore, under same reaction time, the difference of gas yields between these two conditions decreases as the reaction temperature increasing, as well as decrease with the increase of oil vapor partial pressure.

STUDY ON THE INFLUENCE OF IRON NAPHTHENATE ON THE DEMULSIFITION OF AGING CRUDE OIL AND THE MECHANISM OF IRON REMOVAL

2013, 44(3):  36-40. 

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The influence of iron naphthenate on the stability of oil-water emulsion and the iron removal mechanism of aging crude oil was studied. Results showed that with the increase of iron naphthenate in emulsion, the size of water droplets and water removal rate decreased, oil content in water and the negative value of zeta potential increased, indicating that the stability of emulsion increased. The water and iron removal rates of crude emulsion with BSE-238 demulsifier could be enhanced by adding compound complexing agent of polyaspartic acid and acetic acid (mixed with mass ratio of 1:1) containing 50 mg/L of HCl, NaCl and methanol respectively. The demulsification and deferrization mechanism was discussed by using polarized light microscopy and conductometric titration. It was found that both polyaspartic acid and BSE-238 demulsifier could promote the aggregation of water droplets and reduce the stability of emulsion. Polyaspartic acid could react with iron in crude emulsion and form an ionic water-soluble complex, which could be further removed with the proceeding of dehydration, resulting in the increase of aqueous solution electrical conductivity. The arranged simulation tests showed that the curve of changing in electrical conductivity was consistent with the suggested iron chelating mechanism.

RESEARCH ON A NEW EXTRACTANT FOR REDUCING VISCOSITY AND RESISTANCE OF CRUDE OIL

2013, 44(3):  41-43. 

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DRIVE oil extractant is a new type of surfactant mixture which mainly contains fluorine polyester complex. It is developed to solve difficult problems, such as descaling, viscosity reduction of crude oil, declining of production and oil recovery rate. A series of tests in laboratory was carried out to study its function and performance. Test results show that this oil extractant can effectively reduce the viscosity of heavy crude, thus the fluidity and rheological property of crude oil are improved, besides, it also can help crude to separate from grease stain and scale quickly. Experiments of film forming and corrosion tests show that the characteristic of film forming with this oil extractant could reduce the adhesive force of particle surface; furthermore, this extractant will not cause heavy corrosion of equipment steel parts. The results of field experiments indicate that DRIVE oil extractant shows excellent oil displacement efficiency.

PERFORMANCE OF VARIOUS CATALYTIC MATERIALS ON THE REMOVAL OF TRACE OLEFINS FROM REFORMATE

2013, 44(3):  44-49. 

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The performance of various molecular sieve catalysts on the removal of trace olefins from reformate was investigated. Results of catalyst evaluation show that the pore structure of molecular sieve, acidity of catalyst and heavy components in reformate have great influence on removing trace olefins from reformate. Compared with clay, catalyst containing a suitable amount of modified REY molecular sieve exhibits good activity, stability and regeneration property.

EFFECT OF SULFUR CONTENT IN FEEDSTOCK ON THE PERFORMANCE OF PS-VI CCR CATALYST

2013, 44(3):  50-53. 

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The performance of PS-Ⅵ CCR catalyst prior and post to processing high sulfur feeds was compared. It can be seen that running under high sulfur environment, the yield and RON of C5+ liquid product are only slightly lower, which means that PS-Ⅵ catalyst possesses good resistance to sulfur poisoning. When stop using high sulfur feed, the sulfur content of feed decreased, and gradually the sulfur content of catalyst could be returned to normal level. Moreover, the effect of temporarily sulfur poisoning on catalyst activity and service life is non-significant.

CHARACTERIZATION AND PERFORMANCE EVALUATION OF LARGE CRYSTAL SIZE TS-1 MOLECULAR SIEVE PREPARED FROM INORGANIC MATERIALS FOR AMMOXIMATION OF CYCLOHEXANONE

2013, 44(3):  54-59. 

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In this paper, a large crystal size TS-1 molecular sieve was synthesized using inorganic silica sol and TiCl3 as silicon source and titanium source respectively. The synthesis of cyclohexanone oxime by ammoximation of cyclohexanone was carried out over the prepared TS-1 molecular sieve in a continuous slurry reactor at 75 oC and WHSV of 6 h-1. The fresh and used TS-1 molecular sieve samples were characterized by XRD, XRF, FT-IR, SEM, TEM and N2 adsorption-desorption methods. It was found that the structure of TS-1 molecular sieve samples prior and post to catalytic reaction was basically unchanged. Within running 190 h, the conversion of cyclohexanone and the selectivity of cyclohexanone oxime maintained around 99.0% and 96.0%, respectively, which indicated that the catalytic activity and stability of the prepared large crystal size TS-1 molecular sieve was similar, or even better than that of TS-1 molecular sieve prepared from organic materials. Furthermore, this TS-1 molecular sieve could be easily separated from the reaction mixture, and after regeneration its catalytic performance was close to that of fresh one.

A RESEARCH OF LUBRICATING GREASE FOR AIRCRAFT PROTECTION

2013, 44(3):  60-62. 

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In order to meet the requirements of protecting aircraft parts in various external field environments, a type of lubricating grease for aircraft protection was developed using polyolefin synthetic oil (PAO) as base oil and aluminum stearate as thickener to prepare basic grease, and then adding tackifier under certain conditions. The performance of this prepared grease was evaluated comprehensively and the results show that this grease possesses excellent adhesion, rust protection, water resistance and low temperature performance, which can well meet the requirements of national military standard GJB 2095-94. Comparing with 3＃ ship grease used as an aircraft protecting grease presently, their water resistance and adhesion properties are similar, however, the rust protection property and low temperature performance of this prepared aircraft protection grease are much better.

EFFECT OF LAURIC DIETHANOLAMIDE ON THE BIODEGRADABILITY AND SERVICE PERFORMANCE OF HYDRAULIC OIL

2013, 44(3):  63-66. 

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The impact of lauric diethanolamide (abbreviated as LDEA) on the biodegradability of HM46 mineral hydraulic oil and service performance, such as lubricity, anti-wear and friction reduction, corrosiveness, demulsibility and anti-foam ability was investigated. Test results indicated that LDEA biodegradation accelerant not only could enhance the biodegradability of said hydraulic oil effectively, but also could improve the friction reducing property and demulsifying ability of said oil; yet its effect on anti-wear, anti-corrosion and anti-foaming performance was little.

RESEARCH ON THE PERFORMANCE OF REGENERATED LUBRICATING OIL FOR ALUMINUM ROLLING

2013, 44(3):  67-70. 

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Regenerated lubricating oil for aluminum rolling was obtained by vacuum distillation of waste rolling oil. The physico-chemical properties, chemical composition, tribological properties and oxidation stability of the regenerated rolling oil were analyzed and compared with those of fresh rolling oil and rolling oil in use. Results showed that the physico-chemical properties and tribological performance of the regenerated rolling oil could reach the requirements of aluminum rolling, and large molecules in regenerated rolling oil were less than those of rolling oil in use. However, the oxidation stability of regenerated rolling oil still needed to be improved. By adding antioxidant the oxidation stability of regenerated rolling oil met the requirement of aluminum rolling, since then, the regenerated rolling oil could be recycle with assurance of aluminum product quality.

HEAT TREATING SERPENTINE POWDER AND ITS EFFECT ON THE TRIBOLOGICAL PROPERTIES OF LUBE BASE OIL

2013, 44(3):  71-74. 

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In order to improve the tribological properties and the bonding strength with friction pair of lube additive with ultra-fine serpentine powder, on the basis of TG-DSC analysis, the influence of heat treatment temperature on the crystal structure and composition of ultra-fine serpentine powder was investigated. Then, ultra-fine serpentine powders treated under various temperatures were added into lube base oil respectively to study their tribological properties. The results showed that with the increase of heating temperature, the adsorbed water, interlayer water and structural water were removed from the serpentine powder gradually. When taking off structural water under high temperature, serpentine decomposed to form forsterite and silica. The tribological performance of lube base oil with serpentine powder treated at 200 ℃ was improved significantly. Compared with base oil, the friction coefficient and wear scar diameter of lube oil with 1% of serpentine powder were much lower, and it also exhibited self-repairing function.

CORROSION CAUSE ANALYSIS OF FRACTIONATOR IN DELAYED COKING UNIT AND IMPROVEMENTS

2013, 44(3):  75-78. 

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Corrosion of trays at the top part of fractionator in delayed coking unit of SINOPEC Luoyang Petrochemical Company was detected during revamping, thus, an analysis of corrosion causes was carried out. It seemed that using high salt feed and recycling heavy waste oil with high salt and high water content were the main causes, as well as improper operation of washing step. Considering the feed properties, operation parameters and equipment conditions, some countermeasures were applied, such as strengthening the monitoring of salt content in feed, improving the heat distribution at the top part of fractionator, adding a water pipe for washing at the top part of fractionator, optimizing the side streams recycle and so on. Since then, the salt deposition in fractionator was improved significantly, and it is good for a long-term operation.

APPLICATION OF DOMESTIC PVDF HOLLOW FIBER MEMBRANE IN REFINING WASTEWATER ADVANCED TREATMENT FOR RESUE

2013, 44(3):  79-82. 

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Membrane bioreactor (MBR) is applied in refining wastewater advanced treatment for water reuse at SINOPEC Hainan Petrochemical Company. Using domestic PVDF hollow fiber membrane to substitute the import one, the quality of treated effluent still can meet the quality requirements for reuse as makeup of circulating water, having average COD of 41 mg/L, average hydrocarbons and NH3-N of below 1 mg/L and 0.81 mg/L, respectively. Keeping membrane flux less than the design value could slow down the rate of membrane fouling and maintain a stable membrane flux. However, in order to keep the domestic PVDF hollow fiber membrane under good conditions, proper online cleaning and routine offline cleaning are essential, besides, retaining appropriate sludge concentration and discharging sludge regularly are also important.

ARTIFICAL NEURAL NETWORK MODELING APPLIED TO HYDRODENITROGENATION OF GASOLINE AND DIESEL

2013, 44(3):  83-87. 

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The hydrodenitrogenation (HDN) experiments of five low-quality feeds of mixed gasoline and diesel were carried out in an 100 mL hydrogenation device under the conditions of using Ni-Mo-P/Al2O3 catalyst, with reaction temperature of 320—360 ℃, space velocity of 1.2—2.0 h-1, hydrogen to oil ratio of 350—550 and reaction pressure of 6—8.5 MPa. Based on the experimental data, the prediction models for HDN rate of these mixed feeds were established by BP neural network and RBF neural network respectively. The calculation results show that the average relative error of BP neural network in predicting HDN rate is 3.42%, which of RBF neural network is 2.58%. Both of them could meet the industrial prediction requirements, however, the prediction performance of that by RBF neural network seems better. The effects of feed properties and process conditions on HDN rate of mixed feeds are further studied with RBF neural network. The sequence of feed properties affecting HDN rate is as follows: sulfur content > density > nitrogen content > 50% distillation point > viscosity > bromine value. The sequence of process conditions affecting HDN rate is as follows: temperature > space velocity > pressure > hydrogen to oil ratio. These results are helpful to optimize the HDN process conditions for treating mixed feeds of gasoline and diesel.

APPLICATION OF BP NEURAL NETWORK MODEL TO INVESTIGATE THE PROCESS CONDITIONS OF AROMATIC OIL HYDROGENATION

2013, 44(3):  88-92. 

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Back-propagation (BP) neural network was used to establish a model to predict the removal rate of polycyclic aromatic hydrocarbons (PAHs) in aromatic oil during hydrogenation process. The effects of reaction time, temperature, and pressure on removing PAHs were investigated respectively with single-factor experimental method. Then, the obtained experimental results were used to build a training network by matlab software. The trained BP neural network was adopted to predict the isolated points existed among levels of single-factor experiments. Finally, the optimum process conditions of aromatic oil hydrogenation identified by the experimental verification were determined as follows: a reaction time of 7 h, a reaction temperature of 279 ℃ and reaction pressure of 9 MPa. Under such conditions, the PAHs removal rate reached 47.89%. Moreover, the influences of catalyst to feed ratio and solvent involved were studied based on the optimized conditions. Results showed that the PAHs removal rate could be 51.02% with catalyst to feed ratio of 0.3, and the PAHs removal rate further increased to 54.29% when adding toluene as solvent.