Table of Content

12 June 2012, Volume 43 Issue 6

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STUDY ON THE HYDRODYNAMICS CHARACTERISTICS OF EXTERNAL-LOOP AIRLIFT SLURRY REACTORS

2012, 43(6):  1-5. 

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The prediction of gas holdup and slurry circulating velocity is important in the design of external-loop airlift slurry reactors. The effect of superficial gas velocity, fine particle concentration, flow resistance of slurry in the downcomer on the overall average gas holdup and slurry circulating velocity were investigated in a novel type of external-loop airlift slurry reactor cold test system. The results suggest that the overall average gas holdup increases with the increase of superficial gas velocity and flow resistance in downcomer, and decreases with the increase of fine particle concentration; the slurry circulating velocity increases with the increase of superficial gas velocity, and decreases with the increase of fine particle concentration and flow resistance in downcomer. An empirical correlation was developed to predict the overall average gas holdup; based on the momentum balance under steady state operating conditions, a model was developed to predict the slurry circulating velocity; on the whole, good agreements between the calculated and measured values were obtained. These results are useful for the design of novel reactor.

STUDY ON THE ADSORPTION REMOVAL OF SULFUR CONTAINING COMPOUNDS IN FCC GASOLINE

2012, 43(6):  6-10. 

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The adsorptive removal of sulfur containing compounds in FCC gasoline over S Zorb adsorbent was studied by using GC-SCD technique. Results showed that the removal of sulfur containing compounds in FCC gasoline from hard to easy were in the order of C3-/C4-thiophene

PARAFFIN ISOMERIZATION TECHNOLOGY FOR REDUCING BENZENE CONTENT OF GASOLINE FRACTION

Qiuping Zhang

2012, 43(6):  11-15. 

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The conversion rules of benzene, methyl cyclopentane and cyclohexane components over an industrial mid-temperature isomerization catalyst were studied by a laboratory evaluation device. Test results showed that under medium temperature isomerization conditions, benzene in the feed could be converted completely; when reaction temperature was less than 220 ℃, benzene converted to methyl cyclopentane and cyclohexane mainly with little cracking products; with the increase of reaction temperature, products obtained by ring opening and cracking increased. The conversion of methyl cyclopentane increased with the increase of reaction temperature; at low temperature cyclohexane was its main product, with the increase of reaction temperature the cracking products increased significantly. The same with the conversion of cyclohexane, only methyl cyclopentane was the main product from converting cyclohexane at low temperature. Process schemes for benzene removal of feeds with various benzene, methyl cyclopentane and cyclohexane (B+MCP+CH) contents were proposed as follows: for feeds with relatively low (B+MCP+CH) contents, the existing isomerization process scheme could be used to realize the complete conversion of benzene with a little change of product octane number and liquid yield; for feeds with high (B+MCP+CH) contents, the combined process of fractionation and isomerization should be a good choice, by optimizing process conditions product with high (MCP+CH) content and higher octane number could be obtained.

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PREPARATION OF MESOPHASE PITCH CARBON FOAM FROM FCC SLURRY OIL

2012, 43(6):  16-19. 

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Mesophase pitch-based carbon foams were prepared from aromatics rich FCC slurry oil. The effect of carbonization temperature (800—1 400 ℃) on the microstructure, surface properties, microcrystal structure and shape of the prepared carbon foams was studied using a box resistance furnace under air diluted with 1 L/min nitrogen conditions. Carbon foam samples prior and post to carbonization were characterized by SEM, FT-IR and XRD techniques. Results showed that there were large amount of functional groups on the surface of the mesophase pitch carbon foam, such as C-H, C=O and COO- groups. After carbonization, the content of COO- and C-H groups reduced greatly, meanwhile, the content of O-H group increased. However, when carbonization temperature exceeded 1 100 ℃, the content of such functional groups on the surface of carbon foam was basically unchanged. With the increase of carbonization temperature, the shape and microcrystal structure of the carbon foams were improved, and the interlayer spacing of the microcrystal became regularly, which was helpful to form graphite microcrystal structure. On the whole, the optimum carbonization temperature was selected as 1 100 ℃，carbonizing under such temperature, good shape of carbon foam sample with pore size in the range of 150—300 μm could be obtained and its microcrystal structure parameters were as follows: La=2.5 nm, Lc=2.31 nm, N=10 and d002=0.347 6 nm.

A RESEARCH OF INTRINSIC VISCOSITY OF α-HEXYLENE/α-OCTENE/α-DODECENE TERPOLYMER

2012, 43(6):  20-24. 

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A terpolymer of α-hexylene/α-octene/α-dodecene was synthesized by bulk polymerization using TiCl4/Al(Et)3 composite catalyst and α-olefin monomers. Effects of polymerization conditions on the intrinsic viscosity of polymer were investigated. The experimental results showed that under the optimum polymerization conditions of using 0.095 g of main catalyst TiCl4 and 0.12 mL of co-catalyst Al(Et)3, V(α-dodecene):V(α-octene):V(α-hexylene) = 4:2:1 (total monomers volume of 40 mL), reaction temperature of -3 ℃ and reaction time of 48 h, the intrinsic viscosity of the synthesized polymer could be up to 15.40 dl/g. The characterization results by FT-IR, XRD and 1HNMR showed that after alcohol washing, the synthesized polymer was free of monomers, and it was the objective α-olefin polymer with low crystallinity to be used as drag reduction agent.

DEVELOPMENT OF HIGHLY SELECTIVE AND FLEXIBLE HYDROUPGRADING TECHNOLOGY (MHUG-II)

2012, 43(6):  25-30. 

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Based on the intensive studies on the chemical reactions of hydrotreating and hydroupgrading process, a flexible hydroupgrading process, MHUG-II, having three reaction zones and separate feeding systems was developed and put into practice in pilot plant. The influence of reaction parameters on the product distributions and product qualities was investigated, as well as the adaptability of MHUG-II process to various feedstocks. Test results showed that as comparing with conventional hydroupgrading process under similar operating conditions, during MHUG-II process the yield of diesel fraction increased 8.41 percentage points, the cetane number of treated diesel was higher 2.7 units and the potential content of aromatics in naphtha was 3.9 percentage points more. MHUG-II process enhances the selectivity of hydroupgrading reactions significantly; it is an optimum approach to be used to produce clean diesel fuel from various inferior feedstocks including FCC light cycle oil, straight-run diesel fraction and coker gas oil economically.

A DISCUSSION ON RESIDUE HYDROGENATION PROCESS AND ENGINEERING TECHNOLOGY

2012, 43(6):  31-39. 

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The present status, developing trend and engineering research of four dominating residue hydrogenation technologies including fixed bed, ebullated bed, moving bed and slurry bed are presented briefly in this paper, as well as research on the combined process of residue hydrogenation and catalytic cracking. Among these four, fixed bed hydrogenation technology is the most mature, fast developing and being widely use one; ebullated bed and moving bed hydrogenation technologies are becoming mature and popular; as to slurry bed hydrogenation technology, it has completed its commercial trial and in the stage of industrial demonstration. Based on the process characteristics, adoptability to feedstock, requirements of products and operating conditions, some selections of processing schemes from these four hydrogenation technologies are proposed. Besides, to process heavy inferior feedstocks economically, more attention should be paid on the flexible combination of various residue hydrogenation technologies, integrated processes of residue hydrogenation with catalytic cracking and so on in the coming future.

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STUDY ON THE OPTIMIZATION OF HIGHLY SELECTIVE CONVERSION ZONE IN MCP TECHNOLOGY

2012, 43(6):  40-43. 

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The optimization of highly selective conversion zone for olefin rich light gasoline in MCP (Maximizing Catalytic Propylene) process was studied and its industrial application at Yangzhou Petrochemical Company was disclosed. The results of industrial application showed that in the selective conversion zone, when adopting the technique of regenerated catalyst met heavy recycle oil (HCO) prior to light gasoline feed in, at a HCO recycle amount of 0.3 t/h, the mass fraction of propylene in LPG could be increased by 2.34 percentage points and the propylene yield could be increased by 0.84 percentage points. The selective located coke on the catalyst formed by the contact of HCO with hot regenerated catalyst could enhance the shape selective function of molecular sieve catalyst, which resulted in converting light gasoline to more propylene.

DEVELOPMENT AND COMMERCIAL APPLICATION OF CATALYTIC REFORMING PRE-HYDROGENATION TECHNOLOGY FOR HIGH NITROGEN FEEDSTOCK

2012, 43(6):  44-48. 

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The technology of catalytic reforming pre-hydrogenation for processing feedstock with high nitrogen content, including straight-run naphtha blending with coker naphtha or FCC naphtha mid fraction, and its tailor made FH-40C hydrorefining catalyst were developed by Fushun Research Institute of Petroleum and Petrochemicals. Commercial running results showed that FH-40C catalyst had good adaptability to various feedstocks, with high HDS and HDN activities and excellent stability; when treating feedstocks of straight-run naphtha blending with less than 20%（w）of coker naphtha or FCC naphtha mid fraction, the qualities of the treated naphtha could well meet the requirements for catalytic reforming feedstock. In addition, FDAS-1 de-arsenic absorbent and FHRS-1/ FHRS-2 silicon trap catalysts for compatible use were also developed and they exhibited good combination effect for long-term running of the unit.

AN ANALYSIS OF CONTROLLING WATER CONTENT IN ADSORBENT OF p-XYLENE SEPARATION UNIT

2012, 43(6):  49-52. 

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In this paper, the water balance in para-xylene separation unit is discussed. The effect of water in adsorbent on the stability and selective adsorption performance of the adsorbent is analyzed, finally, measures for keeping the optimal water content of adsorbent are put forward, such as proper controlling the amount of water injection, monitoring the water content in feed and tracing water balance daily, to prolong the service life of adsorbent and ensure a safety running of the unit under optimum conditions.

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EFFECT OF DRYING AND AGING CONDITIONS ON THE PROPERTIES OF PSEUDO-BOEHMITE

2012, 43(6):  53-57. 

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In the capacity expansion of pseudo-boehmite production unit, a belt filter is introduced to substitute the conventional plate-frame filter plus tank wash. It is found that the pore volume of product from this new production line is much lower than that from the conventional one. The effect of aging and drying conditions on the properties of pseudo-boehmite samples is studied in laboratory simulating the industrial production process and the obtained samples are characterized by XRD, N2 adsorption, DTA, FT-IR and TEM techniques. Test results show that both aging and drying conditions have great impacted on the pore structure of samples obtained. In the case of fast washing, due to lack of aging time, the crystallinity of material is low, if slow-drying (in oven) is followed, large pore volume pseudo-boehmite product with high crystallinity can be obtained; on the contrary, if fast drying (spray drying) is adopted, only poor quality product is obtained. However, prolonging aging time to increase the crystallinity of slurry prior to fast drying is also helpful for obtaining pseudo-boehmite product with large pore volume. Based on the above research results, measure of slurrying the filter cake from belt filter to prolong material aging time is proposed and put into practice on the industrial unit, since then large pore pseudo-boehmite is produced from the belt filter production line successfully.

STUDY ON THE REACTIVATION OF HYDROCRACKING PRETREATING CATALYST

2012, 43(6):  58-61. 

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Spent hydrocracking pretreating catalyst was regenerated under control temperatures; the well regenerated catalysts were further treated with suitable assistant agents under post-processing conditions to obtain reactivated catalysts. Catalysts prior and post to reactivation were characterized by means of nitrogen adsorption, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy, as well as evaluation of catalytic activity. Results showed that with the increase of regeneration temperature, the pore structure of the catalyst restored gradually and the number of small pores (less than 4 nm) decreased. The post-processing of regenerated catalyst could improve the catalyst pore structure significantly, help the active components well disperse on the catalyst surface and promote the active metals to be sulfurized, thus the activity of the reactivated catalyst was even higher than that of the fresh catalyst.

STUDY ON THE FACTORS AFFECTING n-HEPTANE HYDROISOMERIZATION OVER RARE EARTH MODIFIED MCM-41 CATALYSTS

2012, 43(6):  62-66. 

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Factors affecting the conversion and selectivity of n-heptane hydroisomerization over rare earth modified MCM-41 catalysts were investigated by orthogonal experimental design. Test results showed that the six factors affecting isoheptane selectivity were in the order of reaction temperature > rare earth type in modified support > H2 flow rate > phosphomolybdic acid content in catalyst > Ni content in catalyst > reduction temperature; factors affecting the conversion of n-heptane were in the order of reaction temperature > Ni content in catalyst > H2 flow rate > phosphomolybdic acid content in catalyst > reduction temperature > rare earth type in modified support. The orthogonal test results were further optimized as follows: using La-MCM-41 support, catalyst having Ni mass fraction of 5% and phosphomolybdic acid mass fraction of 20%, H2 flow rate of 120 mL/min, reaction temperature of 300℃ and reduction temperature of 370℃, under such conditions the conversion of n-heptane was 13.5%, and isoheptane selectivity reached 68%.

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MEASURES TO PROLONG THE SERVICE LIFE OF RN-10B HYDROTREATING CATALYST

2012, 43(6):  67-70. 

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In this paper, some measures to prolong the service life of RN-10B hydrotreating catalyst in the gasoline and diesel fuel hydrotreating unit of SINOPEC Tahe Branch were introduced, such as monitoring the operation of feedstock filter, protecting feedstock and desalted water with inert gas, controlling the content of non-metallic/metallic inorganic compounds in feedstock, optimizing the hydrogen to oil ratio, adopting suitable catalyst and guard catalyst combination, properly adjusting the content of H2S in recycle hydrogen and the temperature of catalyst bed. Since applying these technical measures, till June 2011 the operation period of RN-10B catalyst was 501 d longer than the design value and the processing capacity of per unit catalyst was also higher than the design value (a 0.5 kt/kg increase).

SYNTHESIS AND TRIBOLOGICAL BEHAVIOR OF A NITROGEN-CONTAINING BORIC ACID ESTER FROM FATTY ACID METHYL ESTER

2012, 43(6):  71-75. 

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A novel nitrogen-containing boric acid ester was synthesized from fatty acid methyl ester to be used as lubricant additive. The synthesized additive was characterized by FT-IR technique and its tribological performance in various base oils, e.g. the effect of friction time and load on PB value and wear scar diameter (WSD), were investigated using a four-ball tester. The morphologies of the worn scars were analyzed by means of scanning electron microscopy and energy dispersive X-ray spectroscopy to study the effect of said novel additive on the compositions and chemical states of the friction surface film．Results showed that this nitrogen-containing boric acid ester additive exhibited excellent extreme pressure anti-wear performance. Boron was detected from the worn surface of tested steel ball, which indicated that a lubricating film containing boron was formed on the friction surface by physical adsorption and chemical reaction, resulting in an enhancement of extreme pressure anti-wear function.

STUDY ON THE PREPARATION OF ACIDIZING CORROSION INHIBITORS BY MANNICH REACTION

2012, 43(6):  76-79. 

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Corrosion inhibitors were synthesized by Mannich reaction using ketones, amines and aldehydes as raw materials and the process was monitored by in-situ infrared spectroscopy. The effect of various ketones and amines on the corrosion resistant performance of the synthesized inhibitors was investigated by static weight loss tests. Test results showed that the corrosion inhibitor synthesized by aromatic ketone, formaldehyde and aromatic amine was a kind of mixture with good corrosion resistant performance. When the corrosion medium was 15% HCl solution, system containing 1% of said inhibitor, at a system temperature of 90 ℃ and a contact time of 4 h, the corrosion rate was only 1.10 g/(m2?h), which indicated that the performance of this corrosion inhibitor met the requirement for first-class acidizing corrosion inhibitor in petroleum and natural gas trade standards.

STUDY ON THE REMOVAL OF CO2 FROM SIMULATED FLUE GAS BY AMMONIA BUBBLE ABSORPTION

2012, 43(6):  80-83. 

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To reduce the emission of CO2, an approach of absorbing CO2 from simulated flue gas by aqueous ammonia to generate ammonium bicarbonate was studied. The effect of ammonia concentration, CO2 content in flue gas and gas flow rate on the removal rate of CO2 was investigated. Results showed that with the increase of ammonia concentration in solution, the absorption of CO2 enhanced, but the content of ammonia in the exhaust gas increased as well, so the optimum mass fraction of ammonia in solution was 8%—10%; the increase of gas flow rate and CO2 content in flue gas had negative effect on the absorption of CO2, the appropriate flow rate of inlet gas was 0.6 L/min and the volume fraction of CO2 was 10%. Adding some zeolite particles in aqueous ammonia could improve the CO2 removal rate significantly. It was found that the reaction products were mainly ammonium bicarbonate.

APPLICATION OF BOILER WATER TREATMENT AGENT EWPT-6352 IN THE BOILER SYSTEM OF A REFINERY

2012, 43(6):  84-87. 

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A novel boiler water treatment agent EWPT-6352 was applied in the boiler system of the 500 kt/a FCC unit in Nanchong Oil Refinery. The application results indicated that EWPT-6352 agent could effectively control the pH value of the boiler water, increased the silica concentration of the boiler water due to concentration , and also reduced the waste discharge rate. At the same time, the steam quality was improved with less Na+ and SiO2 taken along. Good economic and social benefits were obtained with the application of this novel boiler water treatment agent due to energy saving and emission reduction of the boiler system.

APPLICATION OF CHEMOMETRICS TECHNIQUE IN THE PREDICTION OF FCC PRODUCT DISTRIBUTIONS PROCESSING HEAVY OIL

2012, 43(6):  88-92. 

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The building of a heavy oil database, which containing massive evaluation data of heavy oil catalytic cracking obtained from the State Key Laboratory of Heavy Oil Processing, China University of Petroleum (Beijing), is introduced. On this basis, by using part of the data of heavy oil properties and product distributions as training data and adopting chemometrics correction theory, mathematical correlation models of heavy oil physicochemical properties and product distributions in catalytic cracking process are set up. Validation of the models is carried out using another part of the data from the database. Results show that the product distributions of heavy oil catalytic cracking can be predicted with mathematical correlation models built by correction theory fast and accurately.

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STUDY ON THE GASOLINE BLENDING OPTIMIZATION MODEL BASED ON HYDROCARBON GROUP COMPOSITION

2012, 43(6):  93-97. 

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Gasoline blending model is a key factor for ensuring the qualified rate of gasoline product, as well as to improve profit. In this paper the quantitative relationship between physicochemical property and hydrocarbon group composition of gasoline is figured out to study the optimization of gasoline blending model, and the concrete forms of objective functions and constraint conditions are provided. According to the characteristics of this model, it is solved by adjoint equation method. Case studies of adopting this model show that the precision of model prediction is high, thus, it can provide technical foundation for optimizing gasoline blending and predicting product quality indexes.

EVALUATION OF DEMULSIFIERS FOR DEMULSIFICATION/DEHYDRATION OF VENEZUELA HEAVY CRUDE OIL AND OPTIMIZING ELECTRICAL DESALTING OPERATION CONDITIONS

2012, 43(6):  98-102. 

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Five types of demulsifiers and their combinations were evaluated by means of thermo-chemical sedimentation dehydration and electrical desalting test, finally, oil soluble DE-2 was selected as the optimum demulsifier for electrical desalting of Venezuela heavy crude oil. The operation conditions for Venezuela heavy crude desalting were investigated by single factor analysis and orthogonal test using a SH-Ⅱ type electric desalter. Results showed that under the optimum desalting conditions of using DE-2 demulsifier with a dosage of 8 μg/g, weak electric field intensity of 500 V/cm, strong electric field intensity of 1 050 V/cm, both treating time of 15 min, sedimentation time of 30 min and system temperature of 130℃, the water content of the treated crude was 0.196%, which could meet the requirement for downstream processing.