Table of Content

12 June 2013, Volume 44 Issue 6

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EFFECT OF PREPARATION CONDITIONS ON PROPERTIES OF CoMoP HYDROTREATING CATALYST

2013, 44(6):  1-5. 

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The influence of preparation conditions on the properties of CoMoP hydrotreating catalyst was systematically studied by BET, TPR and UV-DRS techniques. It is found that preparation conditions have a distinctive effect on the properties of the catalysts and that lower temperature of impregnation, drying and calcination favors the reducibility of the active components. The air flows during drying and calcination influence the dispersion of the active phase. The amount of CoAl2O4 is related to the calcination temperature and decreases when the catalyst is calcined at a lower temperature. This study suggests that the catalysts with stable properties and a better utilization of the active species can be obtained by the precise control of the preparation conditions.

STUDY ON HYDROGEN TRANSFER INDEX WITH DODECANE CATALYTIC CRACKING

2013, 44(6):  6-11. 

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The catalytic cracking is a chain reaction involving three steps: initiation, propagation and termination. The main reaction mechanisms are the classical cracking mechanism and protolytic cracking mechanism. The latter one can better explain the initiation step in the catalytic cracking of paraffin. The catalytic cracking of dodecane by Y zeolite was used as model reaction to investigate the mechanism of catalytic cracking and hydrogen transfer reaction in this paper. Hydrogen transfer index（HTI，defined as a ratio of the paraffin content over the olefin content in liquid products）is used to investigate the influence of Si/Al ratio, the La content and the P content on the hydrogen transfer performance. The results indicate that HTI is a convenient way to characterize the hydrogen transfer performance of the zeolites in FCC reactions, and the results were also compared with other methods.

PERFORMANCE STUDY OF LaFe1-XCoXO3 AS OXYGEN CARRIERS IN CHEMICAL-LOOPING COMBUSTION

2013, 44(6):  12-16. 

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A series of LaFe1-xCoxO3 oxygen carriers with different Co ratio were prepared by Citric acid complex method, and their properties were characterized by Thermal analysis, X-ray diffraction, Temperature program reduction and Scanning electron microscopy. The catalytic performance of the prepared samples was investigated in chemical-looping combustion of CO. XRD results showed that LaFe1-xCoxO3 oxides possessed perovskite-type structure. TPR results indicated that oxidizing ability of LaCoO3 was stronger than that of LaFeO3. Especially, the sequential redox reaction revealed that LaCoO3 oxide exhibits high oxygen delivery capacity after 10 redox cycles, in each cycle the CO conversion is 100%. Also the structure of LaCoO3 oxide didn’t change after 10 cycles besides new network structure which was formed under high temperature. All the results showed that LaCoO3 was suit to be oxygen carrier in chemical-looping combustion owing to its high activity and stability.

STUDY ON STABILITY OF BLENDING HEAVY OILS BY DYNAMIC THERMAL FOULING METHOD

2013, 44(6):  17-21. 

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A method of dynamic thermal fouling was created to evaluate the stability of blended heavy oil. Using Lanzhou Vacuum Residue as stock, the evaluation conditions were discussed. Under the conditions of flow rate of 10 g/min, reactor wall temperature of 390 ℃ and sampling at 30 h, the reliable evaluation results can be obtained. The method was then used to examine the stabilities of Lanzhou Vacuum Residue (LZVR) with Lanzhou Ethylene Tar (LZET) blending system. The evaluation results that the fouling resistance and the temperature drop in reactor center from the wall increase with the increment of the ratio of LZET/LZVR indicate the decrease of stability of blending system. The results of the method are consistent with the analysis of mass fraction normalized conductivity. This demonstrate that dynamic thermal fouling method can track the phase separation and fouling of blended heavy oil dynamically, which provides supports for industrial blending process.

STUDY ON NITROGEN COMPOUNDS ADSORPTION PERFORMANCE OF SILICA GEL

2013, 44(6):  22-25. 

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The adsorption tests of quinoline in dodecane solution on silica gel by batch scale reactor were conducted. The influence of calcination temperature of silica gel and the adsorption temperature, adsorption time as well as regeneration on the denitrogenation was investigated. It is found that the Langmuir equation is more suitable for fitting the adsorption isotherm. The adsorption results show that silica gel calcined at 400℃ has a better adsorption performance of basic nitrogen compounds, and that under the adsorption conditions of 20℃, the adsorbent to oil ratio of 0. 03 g/g, and the reaction time of 30min, the best adsorption result (for 1500μg/g N sample, N removal >70%) can be obtained. The fact that the basic nitrogen removal keeps in more than 68% after multiple regenerations indicates the good regeneration ability of the silica gel.

STUDY ON FORMULA OF DRAG REDUCER SUSPENSION

2013, 44(6):  26-30. 

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An alcohol-based suspending drag reducer was studied and developed. Based on the theory of solubility parameter, a suitable suspending medium was selected from alcohols and alcohol ethers by simulation software and real measurements. The kinds of density regulator, emulsifier and thickener were determined based on the examination of factors affecting storage stability and heat resistance of the suspending drag reducer. It is suggested that pentanol, 2-methoxyethanol, span80, tween60, EBS and coating agent for polymer particles are the main components of the drag reducer suspension. The apparent viscosity, high/low temperature resistance and drug reduction rate of the suspension prepared were then evaluated. It is found that the polymer particle size and polymer content in suspending drag reducer are the main factors which affect the apparent viscosity of the suspension. The drug reduction rate increases with increasing dosage of the drag reducer suspension, and then tends to flatten when drug reduction rate reaches to the maximum.

STUDY ON REGENERATION OF IONIC LIQUIDS BY REVERSE EXTRACTION WITH WATER

2013, 44(6):  31-34. 

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The desulfurization of gasoline by ILs is widely studied. The regeneration of ionic liquids using distilled water as reverse extraction agent was investigated in our laboratory. The regeneration rate was optimized by varying volume of water, washing time, and extraction temperature. The desulfurization effect was tested for FCC gasoline with the recycled ILs. The results show that the optimal regeneration conditions are：[C7MIM]BF4 are V(H2O):V(ILs)=1:2, extraction time of 5 min at room temperature. The water was then removed by vacuum evaporation. The recyclability of [C5MIM]BF4, [C7MIM]BF4, [C8MIM]BF, [C10MIM]BF4 by water extraction was also examined, and the results indicate that [C5MIM]BF4 represents a certain solubility in water and thus is not suitable to be recycled with water. Whereas, other ionic liquids are almost insoluble in water, and the effect of gasoline desulfurization is still satisfactory, reaching 64.09 %，72.41 %，75.80 % , respectively even through 15 times regeneration.

DEVELOPMENT AND COMMERCIAL APPLICATION OF NEW RESIDUE HYDRODESULFURIZATION CATALYST RMS-30

2013, 44(6):  35-38. 

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An alumina carrier with more concentrated pore size distribution was fabricated, and CoMo/Al2O3 catalysts were prepared by wet impregnation method base on the carrier. The effect of nCo/n(Co+Mo) atomic ratio and promoter on catalyst activity was evaluated. The HDS test results reveal that the catalyst with nCo/n(Co+Mo) of 0.3 possesses the best hydrodesulfurization activity and that introduction of promoter into the catalyst can improve the activity of CoMo/Al2O3 catalysts. Based on these results, RMS-30 catalyst with high hydrodesulfurization activity was developed. The pilot plant results show that the relative hydrodesulfurization activity of RMS-30 catalyst increases by more than 20% compared with the previous generation of residue hydrodesulfurization catalyst RMS-1B. The commercial results also prove the better performance of RMS-30 in terms of removal of sulfur and carbon residue.

DEVELOPMENT OF INFERIOR RESIDUE HYDRODEMETALLIZATION CATALYST RDM-36

2013, 44(6):  39-43. 

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On the basis of inferior residue hydrotreating mechanism, a novel hydrodemetallization catalyst RDM-36 was developed by developing new alumina material to optimize catalyst pore structure, by using new active component loading method to improve catalyst metal capacity and by modifying surface properties to promote catalyst stability. The new catalyst possesses high activity to remove metal and increase conversion of asphaltene. The stability test shows that the residue having vanadium and nickel content as high as about 200?g/g can be stably hydrotreated by grading series catalyst with RDM-36. It is helpful to increase adaptability to feedstock for RDS unit.

INVESTIGATION ON STRUCTURE, COMPOSITION, AND REGENERATION BEHAVIOR OF INDUSTRIAL S ZORB ADSORBENT

2013, 44(6):  44-48. 

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The variations of structure, composition, and chemical properties of S-Zorb adsorbent during the industrial regeneration process were studied. The structure and composition of adsorbent were characterized by XRD and FT-IR analysis. The chemical state changes of sulfur atom on the surface of adsorbent were examined by XPS. The formations of SO42- compounds in bulk phase of adsorbent were discussed, using the XRD phase quantitative analysis combined with the carbon and sulfur content analysis. The morphology of adsorbent was characterized by SEM analysis. It is found that the desulfurization activity of adsorbent is deeply dependent on both the content of zinc silicate phase and the regeneration rate of ZnS phase. The regeneration rate of ZnS phase increases with increasing of the relative content of oxygen during the regeneration process with increase of the by-product ZnSO4 content at the same time. The morphology and particle size of adsorbent are not changed after regeneration.

INDUSTRIAL APPLICATION OF DIESEL HYDRODESULFURIZATION CATALYST RS-2000

2013, 44(6):  49-52. 

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In order to upgrade the diesel product quality, a high performance hydrodesulfurization catalyst RS-2000 developed by RIPP, has been used in No. 4 diesel hydrotreating unit in Zhenhai Refining & Chemical Company, Sinopec. Industrial application results show that using a feedstock blended with 15.5 % CGO, under the process conditions of 5.3MPa in cold high pressure separator, liquid hour space velocity of 2.0 h-1, inlet temperature of the reactor of 352—354 ℃, average bed temperature of 371—373 ℃, and gas to oil volume ratio at the reactor entrance of about 310, RS-2000 catalyst exhibited excellent capability of hydrodesulfurization and hydrodenitrogenation. The sulfur content of diesel product is reduced to lower than 20 μg/g, and the quality of diesel product meets the national diesel standard of grade IV. The sulfur removal rate reaches to 99.7 %, and the nitrogen removal rate is up to 98.0 %. Furthermore, the properties of diesel product have certain improvement, such as cetane number and the content of poly-aromatic hydrocarbons.

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EFFECT OF REDUCTION WITH DIFFERENT H2/CO MOLE RATIOS SYNGAS ON SYNTHESIS PERFORMANCE OF IRON-BASED F-T CATALYST

2013, 44(6):  53-58. 

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The synthesis performance of a spray-dried spherical iron-based F-T catalyst SFT418 reduced with difference H2/CO molar ratio syngases was investigated in a continuous stirred slurry tank reactor under reaction conditions of 250℃, 2.3 MPa, H2/CO = 1.5 and 3000 ml/(g.cat?h) and the bulk composition of the catalyst after reaction was characterized by M?ssbauer (MES). The results indicate that the BET surface area and the pore volume of the reduced catalyst decrease, while the average pore size is the opposite after reduction. The catalyst is easier to reduce with low H2/CO ratio syngas and has more FexC phase and higher conversion at the start-of-run but faster deactivation rate. Higher ratios of H2/CO ratio syngas give the reversive results. It is proven that the most appropriate H2/CO molar ratio of reduction syngas is 20:1.

PREPARATION OF TITANIUM SILICALITE, CHARACTERIZATION AND ITS APPLICATION IN PROPYLENE EPOXIDATION WITH HYDROGEN PEROXIDE

2013, 44(6):  59-63. 

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Titanium silicalite was hydrothermally synthesized with tetraethyl orthosilicate, tetrabutyl titanate and tetrapropyl ammonium hydroxide template. The structures of titanium silicalite were characterized by XRD, UV-Vis and TEM. The characterization results indicate that the samples prepared possess MFI structure and good crystallinity, and no non-frame anatase type TiO2 is found. The performance of catalytic epoxidation of propylene by titanium silicalite was studied in a slurry bed reactor using hydrogen peroxide as oxidant and methanol as solvent. Under the optimized conditions (1.5 g titanium silicalite, 150 mL methanol, 25 mL 30% H2O2, 0.2 mL 2.5% NaHCO3, propylene flow 1 L/min, at 0.2 MPa and 55 °C，reaction time of 1 h), the selectivity and yield of propylene oxide are 98.7%, 87.6%, respectively.

STUDY ON DESIGN PARAMETERS OF CCR REFORMING UNITS

Aizeng Ma

2013, 44(6):  64-69. 

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The effect of the operation parameters such as reaction temperature, pressure, space velocity, hydrogen to hydrocarbon mass ratio, catalyst distribution ratio in the reactors and catalyst circulating rate on the CCR process were investigated. The results show that a maximum octane yield (octane barrel) appears with increase of octane number of reformate. When the octane number of reformate is larger than a fixed value, the aromatics yields for C6 and C7 increase but slightly decrease for C8 and C9+ with increase of octane number of reformate. The design philosophy based on the principle of maximizing octane yield and target aromatics for gasoline-type and aromatics-type CCR units is proposed, respectively. The criteria for determining design parameters for a grass-root CCR unit is made by taking olefin content in reformate, investment of unit and energy consumption into consideration..

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STUDY ON THERMAL CRACKING PERFORMANCE OF RESIDUE OIL IN PRESENCE OF HYDROGEN

2013, 44(6):  70-74. 

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Residue oil was cracked in H2 atmosphere at high temperature for examining its thermal cracking performance in a pilot plant in a once-through way. A residue oil with high metal content (Ni+V=232.86 μg/g) and high carbon residue (19.67%) was used as feedstock. The investigation focuses on the changes of feed conversion and removal of carbon residue, sulfur and metal. The test results indicate that the conversion and desulfurization of feedstock increase and carbon residue and metals in produced oil decrease with the increase of temperature. However, the conversion and desulfurization of feedstock decrease as the liquid hour space velocity increases. High temperature and low velocity can improve the conversion and impurities removal. There are obvious changes in conversion and impurities removal of feedstock in the range of 400～420 ℃ and 1.0～1.5 h-1. The conversion of feedstock can reach to 60%, desulfurization up to 33% and the contents of carbon residue, nickel, vanadium in the cracked oil are 11%, 28 μg/g, 72 μg/g, respectively at conditions of 420 ℃ and 1.0 h-1.

STUDY ON COMPREHENSIVE UTILIZATION OF CAOFEIDIAN VACUUM RESIDUE

2013, 44(6):  75-78. 

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A comprehensive utilization for propane deasphalting process of Caofeidian vacuum residue was researched. The heavy-duty paving asphalt can be produced from the mixture of the de-oiled asphalt from Caofeidian vacuum residue and the furfural extract oil from vacuum residue of SuiZong-361 crude. The quality of the paving asphalt product satisfies with the national standard GT/T 15180-2000. Several cuts with very low content of aromatics, sulfur and nitrogen can be obtained from the deasphalted oil of Caofeidian vacuum residue by the processes consisting of hydrotreating-distillation-hydroisomerization/hydrofinishing. Among of them, the fraction of 280~380 ℃ can be used as high quality solvent, the fraction of 380~460 ℃ and the fraction of >460 ℃ can meet the standard of API Ⅱ and API Ⅲ base oil, respectively.

STUDY ON LOWERING TEMPERATURE OF HOT RELEASING IN RESIDUUM HYDROTREATING UNIT BY HTRI SIMULATION

2013, 44(6):  79-84. 

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The releasing temperature of safety valves on the top of hot low pressure separator is about 360 ℃, but the design temperature of flare pipes is usually bellow 260 ℃. Available methods are needed to decrease the releasing temperature from 360 ℃ to 260 ℃. The HTRI software is used to simulate several cooling schemes, which are compared and analyzed in economy and feasibility. We may draw conclusions that the scheme of embedding the cooling exchangers inside the flare drum of unit is preferred and the schemes of fin pipes and double pipes are fit for installing on flare pipes outside unit.

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STUDY ON HYDROCRACKING PROCESS OF FISCHER-TROPSCH WAX

2013, 44(6):  85-90. 

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It is very meaningful to optimize the hydrocracking process for obtaining high quality fuels from FT wax. After the main factors that have significant effect on the hydrocracking conversion of FT wax were determined through conditional experiment, the central composite design method was used to investigate the influence of single items, interaction items and square items of these major factors on the wax conversion and middle fraction content of products. In order to test the optimum operating conditions, full quadratic models describing the conversion of FT wax and the content of C10-22 fraction of the hydrocracking products were determined based on MATLAB. Results indicate that temperature has a significant effect on the wax conversion, followed by liquid space velocity, pressure and H2/Wax ratio; furthermore, temperature and H2/Wax ratio have a positive effect on the wax conversion while pressure and space velocity have an inverse relationship with conversion rate．The interaction items of temperature and pressure, space velocity and pressure also play a major role in the hydrocracking process．The middle fraction content may reach maximal value under the following conditions: 377 ℃, 5.0 MPa, 1.95 h-1 of WHSV, 820 V/V of H2/Wax ratio.

ANALYSIS AND EVALUATION OF ENERGY SAVING POTENIAL OF HEAT EXCHANGER NETWORK

2013, 44(6):  91-96. 

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Heat exchanger network (HEN) is an important subsystem for energy recovery in process units. The energy utilization efficiency can be effectively improved by optimizing HEN. In order to guide the retrofit of HEN, it is necessary to analyze HEN, point out the energy saving potential and evaluate the difficulty of the energy saving. Based on Pinch technology, the relationship between the actual heat utility consumption and the minimum heat utility requirement is analyzed, and the difference value of them is regarded as the energy saving potential of HEN in this paper. On this basis, an energy saving potential index for evaluating the difficulty of the energy saving is presented, which is the ratio of the energy saving potential to the heat of hot streams in the Pinch section. In addition, the proposed index is applied to the heat integration between different process units. A case study of HEN of a delayed coking unit and a fuel hydrotreating unit is carried out, and the result shows that the energy recovery is increased by 4 537 kW.

COMMERCIAL APPLICATION OF OPERATION OPTIMIZATION SOFTWARE IN STEAM POWER SYSTEM

2013, 44(6):  97-102. 

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Steam power system is the core process of power plant for petrochemical、steel and thermoelectricity enterprises. Operation optimization can result in remarkable economic benefits of energy saving and environment protection. The Guangzhou Branch of Sinopec applied software of PROSS（Process Real Time Optimization for Steam System）by Beijing Yanzhijieneng Technology Corporation to simulate, analyze and optimize the working conditions of boilers and turbines, fuel configuration and steam equilibrium of the power plant. It is proved from the commercial results that with the PROSS technology the optimized production scheme of the power plant can be easily arranged, and operation cost reduction and good economic benefit can be obtained.