Table of Content

12 July 2015, Volume 46 Issue 7

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STUDY ON FLUID FLOW AND MIXING FOR LIQUID-PHASE HYDROGENATION OF LCO IN A TUBULAR REACTOR

2015, 46(7):  1-6. 

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Based on the reaction data of catalytic diesel liquid-phase hydrogenation in a tubular reactor with ratio of height to diameter of 17 and a power-law type HDS apparent kinetic model, the impact of fluid flow and mixing on the reaction with and without a mixer of ceramic membrane was investigated. The results without the mixer show that the liquid flow inside the tube deviates from plug flow model. Adding the mixer makes the liquid flow inside the tube approach plug flow model and the average relative deviation is only 2.72% which explains the main cause of deviation is mixture of gas and liquid rather than back-mixing. Fluid flow inside the liquid hydrogenation tube can be regarded as an ideal plug flow due to the deviation of axial difusion model is close to that of plug flow model.

RESEARCH METHODS OF C8 AROMATICS ADSORPTION EQUILIBRIUM AND MASS TRANSFER PARAMETERS

2015, 46(7):  7-14. 

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The research methods on adsorption equilibrium parameters and mass transfer coefficients of C8 aromatics at present were reviewed. The static and dynamic methods in obtaining adsorption equilibrium parameters and the methods in obtaining mass transfer coefficients, including the intake method, the zero length column (ZLC) method, the pulse method, the breakthrough curves method and the membrane method, were summarized. The principle of various experimental methods and data processing method and application were introduced. In order to develop the industrial process, the static methods for adsorption equilibrium parameters and adsorption quantity and breakthrough curves method for fiting the transfer coefficients of isomers were used in our research. The simulation data were conducted by the computer software (Aspen Plus) to confirm the parameters obtained by the experiment.

MOLECULAR COMPOSITION MODEL OF RESIDUE BASED ON STRUCTURE ORIENTED LUMPING

2015, 46(7):  15-22. 

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The composition information of residue is critically important to the selection of heavy oil cracking process. Due to complex composition of residue, it is difficult to describe the composition of residue by traditional method at the molecular level. Based on the Structure Oriented Lumping (SOL) method, 21 structure units (metal structural groups, hydrocarbon groups and heteroatom groups) and totally 2 791 kinds of typical molecular structural vector were built to describe the molecular composition of residue. This paper built a molecular composition calculating matrix of residue calculated by simulated annealing algorithm, which makes the hydrocarbon composition information and the calculated average molecular structure parameters in conformity with the instrument measurements. The results show that simulated values of residual properties such as CCR, density and structural parameters (fA, CA) are in good coincident with experimental values. This model, based on SOL could be used for quantitative description of other residual composition at molecular level.

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STUDY ON PHASE CHANGE WAXES WITH HIGH MELTING-POINT

2015, 46(7):  23-26. 

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Using 09# wax and 1,6-hexanediamine as raw materials, high melting-point wax is synthesized under the condition of normal pressure without catalyst and exchange gas, which could be used as a phase change energy storage material. The optimal reaction conditions are determined by orthogonal test design, followed by the single variable method. The mole ratio of 09# wax and 1, 6-hexanediamine is 1:0.65, and the low-temperature reaction time is 2-2.5 h at 165-175 ℃，and the high-temperature reaction time is 1.5-2.0 h at 190-195 ℃. The produced phase change wax is tested by differential scanning calorimetry(DSC). The melting enthalpy is greater than 170 J/g, and the melting point is 140-145 ℃. The enthalpy variables and melting point are higher than the current domestic similar products.

STUDY ON APPLICATION OF Fe-BASED OXYGEN CARRIER IN CHEMICAL LOOPING HYDROGEN GENERATION

2015, 46(7):  27-33. 

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CeO2-Fe2O3/LaNiO3 was prepared by citric acid complexation method and immersion method, and was used as the oxygen carrier in chemical looping hydrogen generation. The experiment was conducted under the conditions: ratio of Fe2O3 to CH4 of 2:1, water 0.1 mL, and atmospheric pressure to investigate the effect of reaction temperature. The results show that H2 output increases first and then decreases with increasing Fe loading. The optimum loading of Fe is 15%; Addition of CeO2 improves the stability of the oxygen carrier. Under the condition of atmospheric pressure, ratio of Fe2O3 to CH4 of 2,0.1 mL of water, reduction and oxidation reaction temperature of 800 ℃, the 5%CeO2-15%Fe2O3/LaNiO3 oxygen carrier can be repeatedly used for 100 times with high activity.

STUDY ON SYNTHESIS OF PHOSPHOROTHIOATE AND ANTI-COKING PERFORMANCE

2015, 46(7):  34-36. 

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A kind of coking inhibiter, phosphorothioate, was synthesized using CH3OH, PCl3, and dimethyl sulfone as feed. The anti-coking performance of dimenthyl disulfide (DMDS), phosphodiester and the new self-made coking inhibitor phosphorothioate was investigated, respectively in a tube cracking furnace at the conditions of 800-840 ℃ and atmospheric pressure. The light oil was used as pyrolysis material and steam as inert diluent. The results show that the phosphorothioate，as a new kind of coke inhibitor，has excellent anti-coking performance, better than DMDS and phosphodiester. It is found that the addition of phosphorothioate into light oil can increase the yield of ethylene.

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DEVELOPMENT OF EXTRACTIVE-DISTILLATION TECHNOLOGY FOR STYRENE RECOVERY FROM PYROLYSIS GASOLINE

2015, 46(7):  37-42. 

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The process for styrene recovery from pygas C8 fraction by extraction-distillation technology was investigated. The selection of solvent, polymerization inhibitor and bench scale test were tested, meanwhile the process design package of 30 kt/a extraction-distillation unit and industrial test were finished. The results show that the color of styrene product after decoloration refining is less than 10, the purity is 99.80%. This technology is successfully applied in extractive-distillation plant of Guandong Xinhuayue Petrochem Co. The operation is stable and the operation parameters are all achieved. The industrial results show that the purity of styrene is 99.87%, the platinum - cobalt color is less than 10. The product quality achieves the national superior grade. The total recovery of the process, including pre-fractionation, phenylacetylene hydrogenation, is 94.3%.

RHT TECHNOLOGY WITH LONG OPERATION CYCLE

2015, 46(7):  43-46. 

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By deep analysis of the catalyst deactivation mechanism and reasons for pressure drop and catalyst bed hot point, RHT residue hydrodesulfurization technology with long operation cycle is developed and applied. Series catalysts with good anti-carbon deposition and high capacity for metal deposition were developed. RHT series catalyst showed good activity and excellent activity stability in many industrial applications and created huge economic efficiency for refineries.

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RESEARCH ON PROCESS PARAMETERS FOR SELECTIVE HYDROGENATION OF POLYAROMATICS IN FCC LCO

2015, 46(7):  47-51. 

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The influence of process parameters on hydrogenation saturation of aromatics in FCC light cycle oil over Ni-Mo-W /γ-Al2O3 catalyst was investigated. The results show that different process conditions have different effects on the reaction of polyaromatics into mono-aromatics and then further into saturates. Under the conditions of 330 ℃, hydrogen partial pressure of 6.4 MPa, LHSV of 1.2 h-1 and H2/oil(volume ratio) of 800, polyaromatics saturation rate can reach 80.1%, the total aromatics saturation rate is 16.4% and mono-aromatics yield is 42.6%. Under the reaction conditions and the catalyst used, the maximum yield of mono-aromatics at high polyaromatics saturation rate can be realized.

ANALYSIS OF ACTIVITY DECLINE OF TAIL GAS HYDROGENATION CATALYST IN SULFUR RECOVERY SYSTEM AND COUNTMEASURES

2015, 46(7):  52-57. 

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The analysis indicates that the abnormal phenomena of quench tower, SO2 concentration in flue gas and hydrogenation system during the commissioning of No.2 tail gas treatment system for sulfur recovery is due to the activity decline of the hydrogenation catalyst. It is found that the reason for hydrogenation activity losing is due to the bias current in catalyst bed. Effective measures are then adopted, including sealing part of the reactor entrance opening, adding porcelain ball screen mesh at the top of the catalyst bed and adjusting the operation of the reactor system. The bias current in the catalyst bed is thus controlled effectively and the hydrogenation activity improves significantly by these measures, resulting in smooth operation of the tail gas system of the sulfur recovery unit.

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EFFECT OF HYDROTHERMAL TREATMENT TIME OF SUPPORT ON HDCCR PERFORMANCE OF CATALYST

2015, 46(7):  58-62. 

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This paper studied the effect of hydrothermal treatment time of support on physical structure and HDCCR activity of catalysts. The catalysts were characterized by BET, TPR, Raman spectrum, TG, HRTEM. It is shown that with the increasing of hydrothermal treatment time of the support, the number of -OH groups on the support surface increases. The catalysts made from hydrothermal treated supports have higher specific surface area and lower mean pore size. Those changes indicate that the interaction between metal and support increases with increasing of hydrothermal treatment time, resulting in changes in the structure of active phase of catalysts. The active phase size becomes smaller and the degree of aggregation decreases. The performances of catalysts were evaluated in an autoclave and the results show that the HDCCR and HDS activity of the catalyst are both decreased as the hydrothermal treatment time is prolonged.

APPLICATION OF C8 AROMATIC ISOMARIZATION CATALYST RIC-200 IN DOMESTIC AROMATICS COMPLEX

2015, 46(7):  63-66. 

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The first industrial application of RIC-200 C8 aromatics isomerization catalyst in a 600 kt/a aromatics complex in Hainan petrochemical co. Ltd., SINOPEC was introduced. The complex adopts the domestic technologies. The industrial results indicate that the domestic technology of aromatic complex is successful. The energy consumpton is relatively low and RIC-200 catalyst performs a high activity and selectivity under the high load of 110%. The PX isomerization rate of RIC-200 is 22.86%, the ethylbenzene conversion rate is 27.40%, C8 aromatics loss in a singl-pass is 2.28%. It is concluded that the RIC-200 catalyst can satisfy the demand of maximum PX production for a PX complex.

SYNTHESIS OF BIMETAL ZSM-5/L COMPOSITE ZEOLITE AND ITS AROMATIZATION PERFORMANCE FOR AROMATIZATION REACTION

2015, 46(7):  67-72. 

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The core-shell composite zeolite Zn-ZSM-5/Pt-L was prepared via step by step modification. The surface acidity was regulated by changing the ratio of two metals. The physical and chemical properties were investigated by X-ray diffraction (XRD), N2 adsorption-desorption, ammonia temperature-programmed desorption (NH3-TPD) and in situ Py-FTIR spectroscopy. The light hydrocarbon aromatization performance of catalysts was evaluated using n-pentane as the raw material. The results exhibit that the modification of introducing active metal step-by-step effectively regulates the L/B acid ratio and distribution on the catalyst surface, which could cause more excellent synergism between B acid and L acid. At the loading of Zn and Pt metal of 1.0% and 0.6%, respectively, the catalytic performance reaches the best. The conversion rate of pentane aromatization is 99.1 % and aromatic selectivity is up to 47.2%.

PREPARATION OF HIERARCHICAL POROUS Hβ ZEOLITE AND ITS CATALYTIC PERFORMANCE IN ETHERIFICATION

2015, 46(7):  73-77. 

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The hierarchical porous Hβ zeolite with BEA structure was prepared by alkaline treating Hβ zeolite with NaOH solution. The zeolites before and after treatment were characterized by XRD, SEM, N2 adsorption-desorption, NH3-TPD and Py-IR. The FCC light gasoline etherification was investigated in a fixed bed reactor. The results show that alkali treatment can change pore structure and adjust the amount and distribution of acidic sites effectively. As the alkalinity of NaOH solution increases, part of the microporous structure is destroyed, mesopore and acidity increases. At proper alkalinity, with increasing treatment temperature and time, the specific surface area and acid of the Hβ zeolite decrease. At conditions of 0.2 mol/L NaOH solution, 60 ℃, 0.5 h, the micropore structure of the zeolite can be preserved to a maximum extent while the mesopore is formed. The Hβ zeolite treated at this condition has the best catalytic activity.

STUDY ON FORMULATION OF LOW LEAD PISTON ENGINE FUEL (100LL) AND APPLICATION

2015, 46(7):  78-82. 

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To meet the requirements of environmental protection and standards and performance of a new kind of general aircraft fuel, the performance of compositions of aviation fuel were investigated, resulting in low lead aviation gasoline, which meets the standard of 100LL of ASTM D910-13 and realizes the industrial trial production. Flight tests indicate that the performance of the new developed fuel is similar to the product of the United States. The developed aviation fuel has the characteristics of good evaporation, ignitability, stable properties and low crystallization point. No corrosion to engine parts is observed. The technology fills a domestic gap in this field with broad prospect.

IMPACT OF BASE OIL ON THE PERFORMANCE OF ULTRAFINE BENTONITE GREASE

2015, 46(7):  83-88. 

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The bentonite greases were prepared using T400, T110, 200DN, MVI500,150BS and PAO8 as the base oils, respectively, with bentonite powders before and after ball–milling as thickening agent. The thickness, shear stability, colloid invariability, water resistance, anti-wear and antifriction properties of the prepared greases were investigated. The results show that the performance of ultrafine bentonite grease is improved significantly, compared with the traditional one. And the base oils have huge influence on the performance of ultrafine bentonite greases. The ultrafine bentonite grease prepared with the base oil of T110 has a better shear stability, water resistance and anti-wear property.

OPTIMIZATION OF HEAT EXCHANGER NETWORK OF FCCU WITH PINCH TECHNOLOGY

2015, 46(7):  89-94. 

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Pinch technology was applied to optimize the heat exchanger network (HEN) for a petrochemical enterprise with a capacity of 1.4 Mt/a FCCU. The results show that the energy consumption of the whole FCCU are decreased by 7.88 t/h of 1.0 MPa steam, 3.77 t/h of circulating water and 16 kW of electricity. And the comprehensive energy consumption of the optimized FCCU is decreased by 109.19 MJ/t, equivalent to the benefit of ￥12.213 million/a.

ENERGY UTILIZATION ANALYSIS AND OPTIMIZATION OF S Zorb PROCESS

2015, 46(7):  95-100. 

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S Zorb process is a desulphurization technology for clean fuel production, the energy utilization of the whole device can yet be further improved. In this paper, pinch technology was used to analyze the S Zorb process in a refinery with the help of the grand composite curve. The results indicate that the device consumes overmuch utility, energy saving potential can be about 24%, and meanwhile, the problem of high energy for low energy situation exists in the pockets of the grand composite curve. Two optimization schemes are proposed. In the first scheme, furnace is retained and medium pressure steam is generated as a byproduct, which realizes the cascade utilization of energy, resulting in a benefit of 10.442 million RMB per year. The other scheme is to remove the furnace which leads to the less consumption of fuel gas with a benefit of 10.662 million RMB per year. Both the schemes have low retrofitting costs and short payback periods. A large amount of energy can be saved which contributes to considerable economic benefits.

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A LUMPING-BPNN HYBRID MODEL FOR PREDICTION OF LIQUID YIELD OF DELAYED COKING

2015, 46(7):  101-106. 

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To improve the economic benefit of delayed coking unit (DCU), it’s necessary to establish a precise yield prediction model for various feedstocks and operation conditions. A lumping-BP neural network hybrid model in a cascade form was established for a DCU with capacity of 1.4 Mt/a to predict the liquid yield of the unit, based on the mathematical model of the reactor under the assumption of dynamic balance from 11 lumping dynamic model and the BP neural network input of the mechanism model calculation results and the historical data of key sites. In the case study, the coking diesel yield was predicted by the hybrid model, and compared with the results of mechanism model, empirical model. The results demonstrate that among these three methods, the prediction accuracy of the hybrid model is the best. The impact of the material properties and operating conditions fluctuation on the hybrid model results is small, the root mean square error, mean absolute error and the average relative error is 0.751 percentage point, 0.524 percentage point, 2.01%, respectively.

SEPARATION AND IDENTIFICATION OF NITROGEN COMPOUNDS IN DIESEL FRACTION OF COAL TAR AND PETROLEUM

2015, 46(7):  107-113. 

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In this paper, nitrogen compounds in two kinds of coal tar diesel fraction and three kinds of diesel（FCC diesel, coking diesel and straight-run diesel）were separated and identified. The non-basic nitrogen compounds was separated by silicagel column and the basic nitrogen compounds was extracted from diesel by HCL, then the separated nitrogen compounds were identified by using GC/MS. The results show that in two coal tar diesel fractions, non-basic nitrogen compounds including carbazole and indole as well as basic nitrogen compounds including quinoline, pyridine and aniline are the main nitrogen compounds. The basic nitrogen compounds including pyridine and quinoline are given priority in coking diesel. Straight-run diesel mainly contains non-basic nitrogen compounds including carbazole and a small amount of basic nitrogen compounds including quinoline and aniline. The basic nitrogen compounds are mainly in coal tar diesel fraction and coking diesel, and the non-basic nitrogen compounds are mainly in FCC diesel and straight-run diesel. The kinds and amount of basic nitrogen compounds in coal tar diesel is much more than that in petroleum diesel.