Table of Content

12 July 2017, Volume 48 Issue 7

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STUDY ON BACKFLUSHING PERFORMANCE IN CROSSFLOW MICROFILTRATION PROCESS

2017, 48(7):  1-5. 

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The slurry containing water and alumina fine particles was used to simulate conventional liquid-solid separation system in petrochemical industry. The backflushing performance in the process of cross-flow microfiltration was studied emphatically. The permeate flux, average permeate flux of the whole duration and the particle concentration in filtrate were used to evaluate the influence of back flushing time and back flushing pressure difference. The experimental results showed that the liquid back flushing technology could reduce filtration resistance and recover permeate flux. In the cases of the suspension system with solid holdup 1% and 5%, respectively, the backflushing operation was finished instantly within 1-2 s. The higher the backflushing pressure difference, the better back flushing performance. The optimal backflushing pressure difference is 0.5-0.6 MPa.

SIMULATION STUDY OF NH3 TRANSFORMATION IN CO BOILER OF INCOMPLETE REGENERATION FCCU

2017, 48(7):  6-9. 

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A mixed gas containing NH3, CO, N2 and air with different ratios was used for the simulation study of NH3 transformation at high temperature in CO boiler of incomplete regeneration FCC unit. The results show that nearly 30%-45% NH3 are transformed into NOx at 975 ℃, and the yield of NOx increases with the increase of O2 concentration at outlet of the boiler. The existence of CO in the mixed gas decreases the generation of NOx. The higher combustor temperature and the higher CO concentration can reduce NOx emission significantly.

STUDY ON VANADIUM TRAPPING PERFORMANCE OF Mg-Al SPINEL IN FCC PROCESS

2017, 48(7):  10-16. 

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The performance of phosphorus containing magnesia-alumina spinel for vanadium trapping in FCC process was investigated. The results of FFB tests demonstrate that the phosphorus containing magnesia-alumina spinel can be used to match FCC catalysts with different rare earth content and to improve the product distribution of heavy metal contaminated catalysts. When the composite catalyst consisting of the FCC catalyst containing 4.5% rare earth oxides and the phosphorus containing magnesia-alumina spinel, the total liquid yield is increased by 0.6%, the coke selectivity is improved. However, the dry gas selectivity is similar to FCC catalyst only. Compared with the FCC catalyst, the phosphorus containing magnesium aluminate spinel can preferentially capture the porphyrin vanadium and form a stable compound, thus attenuates the detrimental effect of vanadium on FCC catalysts in steaming aging process.

SIMULATION STUDY OF DIESEL COMBUSTION DURING DETERMINATION OF CETANE IN DIESEL ENGINE

2017, 48(7):  17-21. 

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By the computational fluid dynamics, computational heat transfer and chemical kinetics, a model for pulverization and mass transfer of diesel fuel in FCD-II cetane number machine was established to simulate the changes of combustion parameters of temperature, pressure and speed of airflow in the engine. The results indicate that the temperature and pressure of air due to being compressed is high enough to ignite the fuel at the top dead center (360o angle position) in the case of invariable air volume. When the reading value of the air flow meter is increased from 200 to 800, the compression terminal temperature rises from 426 ℃ to 503 ℃, high enough to ignite the fuel. During fuel combustion, the parameters are increased sharply by rapid combustion in local region in the cylinder and transferred to other regions, resulting in instantaneous variations of temperature, pressure and air speed in cylinder.

RESEARCH ON MODIFICATION OF RESIDUAL OIL BY CHEMICAL ADDITIVE

2017, 48(7):  22-27. 

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The features of vacuum residue from PetroChina Urumqi Petrochemical Company were characterized by high carbon residue, low fluidity and easy coking. A new residue oil additive made from butyl methacrylate (BMA), styrene and maleic anhydride through solution polymerization with benzoyl peroxide as an initiator was added into the residue to investigate the effect on the changes of CCR, fluidity, SARA composition and the coking reaction. The results show that residual oil additive can reduce carbon residue, improve low temperature fluidity and the stability of colloid system of residue oil. Comparing with the blank residue, the conversion rate of residual oil with additive increases by 7.7 percent points, the coking yield decreases by 2.60 percent points. The liquid yield increases 2.06 percent points, among which the yield of gasoline increases by 25.4 percent points, while diesel oil and wax oil decreases by 17.7 percent points and 7.7 percent points, respectively.

STUDY OF IMPROVING MeSH REMOVAL EFFICIENCY BY MODIFIED UDS SOLVENT FROM NATURAL GAS

2017, 48(7):  28-33. 

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The active component that can enhance the adsorption for MeSH was successfully screened by applying quantum chemistry computation method and then was formulated mixed with the original UDS solvent to obtain a modified high efficiency UDS solvent. The equilibrium solubilities of MeSH in the original UDS solvent and the updated solvent were investigated and compared. In addition, the thermal stability and anti-foaming performance of both UDS solvents were evaluated. The absorption experiments were conducted in an atmospheric unit using simulated Chuanxi natural gas as raw material. The results indicate that polyethylene glycol dimethyl ether (PEGDME) has the strongest intermolecular interaction with MeSH molecule, therefore, is expected to be the promising component for improving the removal of MeSH. As compared with the original solvent, the improved UDS solvent shows a higher solubility of MeSH and has a better thermal stability and anti-forming performance. The modified solvent has 10.3 percentages higher removal rate of MeSH and the total sulfur content decreases in purified gas from 70.0 mg/m3 to 54.1 mg/m3, 5.7 percent points higher than original one at the adsorption conditions of gas/liquid volume ratio of 360 and absorption temperature 40 ℃, and atmospheric pressure. The gas quality is improved from the national standard II to the top one.

COMMERCIAL TRIAL OF NOVEL FCC CATALYST FOR NOx REDUCTION

2017, 48(7):  34-37. 

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To reduce NOx emission on MIP-CGP unit in CNPC Daqing refinery, a commercial trial of a novel specially formulated catalyst CGP-1DQ with the function of NOx emission reduction was performed. The results show that when the new CGP-1DQ in catalyst inventory reaches about 40%, NOx emission in flue gas is decreased by 42% to about 656 mg/m3 compared with the level of NOx emission (1 134 mg/m3) in the interrupted period during the trail. However, if compared with the base condition (1 900 mg/m3), NOx emission is decreased by more than 65%. In addition, no negative influence on product distribution and unit running are observed during the operation.

STUDY ON NICKEL SPECIES ON FCC CATALYST BY XRD

2017, 48(7):  38-43. 

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The mechanical mixtures of silica or alumina with NiO, impregnated silica or alumina with Ni sources, together with 5 fresh FCC catalysts and 10 commercial FCC equilibrium catalysts (ECAT) were characterized by XRD to investigate the nickel species on FCC catalyst. The results show that for the samples of NiO mechanically mixed with silica or alumina, NiO was reliably detected when Ni content is higher than 519 μg/g or 694 μg/g, respectively. Compared with the impregnated alumina, NiO can be detected at low Ni contamination content on the impregnated SiO2. As to the alumina impregnated, NiO cannot be detected until the Ni contamination content is over 117 900 μg/g. No NiO can be observed until the Ni content is higher 15000μg/g and 700-2 500 μg/g for fresh FCC catalysts and ECATs, respectively.

PREPARATION OF COMPOSITE MATERIAL RICH IN BRONSTED ACID AND ITS APPLICATION IN RFCC CATALYST

2017, 48(7):  44-47. 

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Ordered mesoporous silica-alumina/kaolin composite rich in Bronsted acid was prepared in situ within kaolin clay by template assembly method, using the silica extracted from kaolin by NaAlO2 as a silica source, NaAlO2 as aluminum source, CTAB as template. The composite materials were characterized by XRD, N2 adsorption and pyridine adsorption FT-IR. Characterization results indicate that the surface area and pore volume of obtained composite material is up to 253 m2/g and 0.43 mL/g, respectively with abundant surface B acid sites. Heavy oil cracking results confirm the significant improvement in conversion and selectivity of the FCC catalyst using the composite material as matrix. The yield of gasoline and total liquid increases by 2.95 and 2.47 percentage points, respectively and the conversion rises by 3.19 percentage points, while the heavy oil and coke decreases by 2.12 and 0.41 percentage points, respectively.

CAUSE ANALYSIS OF HIGHER CONTENTS OF N IN FEED AND WATER IN DRIED AIR IN CONTINUOUS REFORMING UNIT AND CORRESPONDING MEASURES

2017, 48(7):  48-54. 

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The reactor temperature and hydrogen production of continuous reforming unit in Hainan Refining Company began to drop from February 2014 followed by a significant reduction in March, the content of aromatics in reformate and aromatics yield were fallen dramatically. The analysis found that with increasing the proportion of Fotis crude oil with high nitrogen content, the nitrogen content of reforming feed increases; and that the dry efficiency decreases due to insufficient air drier capacity of air compression station and regeneration system, resulting in higher water content in regenerated air and H2O-nitrogen-chlorine coexistence environment which poisons the CCR catalyst. A series corresponding measures were adopted, including: adjusting feedstock composition, optimizing pre-hydrotreating operation, reducing the load and reaction severity of reforming unit appropriately, adding more spare air drier of air compression station, changing air desiccant of reforming regeneration system and increasing the amount of chlorine injection, to control the catalyst poisoning and recovery the activity. The plant operation is returned successfully to normal.

INDUSTRIAL APPLICATION OF MHUG - KHF COMBINED TECHNOLOGY FOR NO.3 JET FUEL PRODUCTION

2017, 48(7):  55-59. 

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The combined process of the medium pressure hydroupgrading (MHUG) and kerosene hydrofinishing (KHF), developed by Fushun research institute of petroleum and petrochemical, was adopted for production of No.3 jet fuel in PetroChina Karamay Petrochemical Co. Ltd. The mixture of coking diesel, FCC LCO and SR diesel was used as feedstock. Industrial application results show that after the jet fuel fraction from MHUG process was deeply hydrofinished under the mild reaction conditions, the aromatics in jet fuel product is reduced from 14.9% to 5.8%, the smoke point rises from 22 mm to 26 mm, in compliant with the quality specification of GB6537-2006.

OPTIMIZATION OF HYDROGENATION UNITS FOR REDUCTION OF DIESEL/GASOLINE RATIO

2017, 48(7):  60-63. 

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In the face of weak diesel market, a refinery reduced the diesel over gasoline ratio through optimization of the production schedule of hydrogenation units. Among of them, the kerosene hydrofining unit was expanded to increase jet fuel production of 0.4 Mt/a; the fractionation system of diesel hydrogenation unit was optimized to yield 0.3 Mt/a gasoline blending component by drawing out more side stream; through stopping diesel side stream drawn out, all VGO hydrotreated diesel fractions were sent to FCC unit as feed to increase 0.06 Mt/a gasoline; optimization of hydrocracking unit increased another gasoline component 0.22 Mt/a. These measures reduced the diesel/gasoline ratio from 1.23 to 0.83 and improved the economic benefit of the refinery.

TECHNICAL ROUTE SELECTION AND OPTIMIZATION FOR PROCESSING LCO

2017, 48(7):  64-69. 

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The comparisons of the processing results of LCO hydrofining, hydrocracking of VGO mixed with LCO, hydrotreating VGO mixed with LCO and LTAG in SINOPEC Wuhan Company were introduced. The results show that LCO hydrofining can only achieve desulfurization, and the hydrocracking of VGO blended with LCO is favorable for the production of petrochemicals and the improvement of diesel cetane number, while LTAG process can produce much more gasoline than that of the hydrotreating VGO mixed with LCO process and is the most economical processing route, but needs severer hydrotreating operation. It is recognized that the LTAG process combined with optimal LCO hydrotreating process is the primary economical choice for LCO processing in Wuhan Company.

STUDY OF HYDROGENATION PROCESS OF HIGH VISCOSITY PAO

2017, 48(7):  70-73. 

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The PAO40 crude product was hydrogenated using Pt-Pd/Al2O3 catalyst developed by the Petrochemical Research Institute of PetroChina and the optimal conditions were determined. The results show that under the optimized operating conditions of hydrofining which are 240-280 ℃, 4.0-8.0 MPa, LHSV of 0.1-0.4 h-1 and hydrogen /oil of 300(v/v), the hydrogenated PAO40 has a similar aromatic content with the PAO40 products abroad. No Saybolt color changes of the hydrogenated PAO40 are observed after light test for thirty days, indicating its good light stability.

STUDY ON EXTRACTION PRETREATMENT OF FULL DISTILLATE OF COAL TAR AND UTILIZATION OF BY-PRODUCT

2017, 48(7):  74-78. 

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The goal of this study was to develop a new processing method for coal tar modification. Coal tar was extracted by binary mixed solvents which consist of toluene and n-heptane. Purified tar and coal tar pitch were obtained in the process. The results indicate that the ash content of coal tar is decreased from 1.89% to 0.03%, TI content is reduced from 9.56% to 0.31%, HI content is lowered from 15.26% to 4.09%, and carbon residue is decreased from 4.07% to 0.39% under the conditions of mass ratio of toluene to n-heptane of 0.5:1, the mass ratio of binary extractant to coal tar 1.5:1, and the extraction temperature 70 ℃. The yield of purified tar which can be used as hydrogenation feedstock is 83.2%. Meanwhile, the by-product, coal tar pitch, was investigated to be used as petroleum asphalt to prepare heavy traffic road pavement by mixing with shale oil pitch from Fushun. The study finds that when the content of coal tar pitch is 10%, the performance of the mixed asphalt meets the quality standard of AH-90.

CAUSE ANALYSIS ON UNQUALIFIED pH OF STRIPPED ACIDIC WATER FROM HYDROGEN PLANT AND SOLUTIONS

song hongyan

2017, 48(7):  79-82. 

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The pH of the condensed acidic water of the shift gas from hydrogen plant was on the low side and not qualified after it was steam stripped, resulting waste water and corrosion of equipments. The trial test found that little effect was observed through adjusting steam consumption. The trouble is solved by revamping of the condensation process of the shift gas. After revamping, the pH of condensed water satisfies the quality requirement of the recycling water. A large amount of water is recycled and corrosion of equipment is avoided. The benefit of 2.774 4 million Yuan was produced in first year because the technical renovation cost is one-time investment. Since the second year after revamping, the economic benefits of 3.924 4 million Yuan/a can be obtained.

REASON AND SOLUTIONS OF FAILURE IN DOCTOR TEST OF HYDROTREATED FCC NAPHTHA

Guang-Cheng PAN

2017, 48(7):  83-87. 

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The doctor test often does not pass for hydrotreated FCC naphtha with 10μg/g sulfur, even lower than 5μg/g mercaptan content. Based on the data of routine doctor test, the reason was analyzed and corresponding solutions were suggested. It is found that the main reason for the failure is the newly formed trace amount of mercaptan with larger molecular weight during FCC naphtha hydrotreating. Those compounds have no influence on the properties of the gasoline. Solutions are: cancelling doctor test for hydrotreated FCC naphtha when national V/VI standard gasoline are the operation objective; increasing the blending ratio of zero-sulfur gasoline component/hydrotreated FCC naphtha; and oxidative sweetening the hydrotreatd naphtha.

RESEARCH ON EFFICACY OF AROMATIC AMINES ADDITIVE IN UNLEAEDED AVIATION GASOLINE

2017, 48(7):  88-92. 

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Grade 95 and 100 unleaded aviation gasolines were obtained by adding aromatic amine antiknock agent in a blank aviation fuel with MON of 93.7. The differences on abrasion resistance of metal in seat and swelling property of sealing element between unleaded aviation gasoline added aromatic amines and leaded fuel with similar MON number were analyzed by measuring the length of grinding crack of 40 Cr metal by ring-on-block experiments and observing mass and volume changes of rubber samples after soaked in gasoline. The results indicate that gasoline with aromatic amines shows worse performance on abrasion resistance and swelling property than leaded gasoline. Anti-oxidants may be employed in aromatic amines added aviation gasoline for weakening the swelling effect on rubber products and abrasion.

ANALYSIS OF ENERGY SAVING ABSORPTION- STABILIZATION SYSTEM BASED ON INTENSIFIED MASS TRANSFER

2017, 48(7):  93-97. 

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This paper introduced a simulated process consisting of mass transfer intensified and energy-saving absorption-stabilization system, which involves a feed preheater for desorption tower, two-stage condenser, and intermediate reboiler. The comparison of the simulated process with a basic process which only consists of a two stage-condenser and intermediate reboiler was conducted. It is found that the temperature of the first-stage condensed liquid phase entering the desorption tower is increased by feed preheater, and the duty of the first-stage condenser is decreased due to the direct mixing of desorbed gas with the gas from the first stage condenser instead of mixing of the desorbed gas with the bottom oil of the absorption tower and the compressed rich gas. Moreover, the mass transfer efficiency of desorption tower is improved and the overall utility consumption is reduced. Compared with the reference process, the energy consumption of the new process is reduced by 22.02%. Gas and liquid loads in the desorption tower are both reduced. The new process has advantages of mass transfer intensification, energy saving and low-loads of gas-liquid phase in the desorption tower.

RAPID COMPOSITION ANALYSIS OF FEEDSTOCK AND PRODUCT OF HYDROTREATING IN LTAG TECHNOLOGY BY NEAR INFRARED SPECTROSCOPY

2017, 48(7):  98-102. 

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Based on the NIR results and the group composition data by SH/T 0606 standard method of 383 FCC diesel and hydrotreated diesel samples, a NIR hybrid analysis model was established using partial least squares (PLS) method. Verification results indicate that the results predicted by model are very close to the standard method and the repeatability even better. It was applied in a refinery LTAG process. The continuous analysis of the compositions of feedstock before and after hydrotreating for 15 days proves the practicability of this rapid analysis method.