As the core of heavy oil upgrading, fluid catalytic cracking(FCC) units have long been the main pillar of economic benefits for petrochemical enterprises in China.This paper reviews the development history of domestic FCC technology and summarizes the current status of FCC technology from three perspectives based on target products:Oil production technology,light olefin maximization technology,and product structure adjustment technology.It emphasizes summarizing the design concepts,main characteristics and commercial application of different FCC technologies,with a particular focus on comparing the differences in reactor types and catalyst.Additionally,research efforts aimed at improving oil quality to meet market demands,enhancing the yields of low?carbon olefins,BTX(benzene,toluene,xylene),and other basic chemical raw materials,as well as optimizing their selectivities,are discussed,providing viable technical solutions for high?quality enterprise development.Future research priorities for FCC technology include feedstock heavy and diversified processing,product quality improvement,flexible product structure adjustment,and cleaner production processes.
To address the challenge of wellbore blockage during the development of a certain oilfield, Y3 crude oil was taken as the research object. Laboratory experiments were conducted to analyze the composition of the crude oil and the main components of wellbore blockage materials.Toluene extraction was performed on formation blockage materials collected from the oilfield, and XRD was used to analyze the composition of toluene?insoluble substances. The soluble fraction was separated into four components, with a focus on studying the composition and properties of asphaltenes in the soluble fraction and Y3 oil samples. Through asphaltene adsorption experiments, oil?water interfacial tension, underwater contact angle, etc., were measured to explore the effects of asphaltene polarity and aromaticity on interfacial properties. The experimental results show that the main minerals of the formation blockage of the wellbore are quartz, feldspar, calcite, etc. Compared with the asphaltene in Y3 crude oil, the asphaltene in the blockage has higher molecular weight, heteroatomic mass fraction and aryl carbon ratiowith minimal wax content in blockage materials. The main cause of wellbore blockage was the adsorption of asphaltenes on sandstone. The heteroatom mass fraction and polarity of asphaltenes had significant effects on adsorption capacity and interfacial tension.
In order to study the effect of hydrocarbon group composition on physical and chemical properties of jet fuel, the coal?based kerosene and biogenic aviation fuel were added to No.3 jet fuel respectively, and the seventeen physical and chemical properties of jet fuel were tested according to the experimental methods specified in GB 6537—2018《Jet Fuel No.3》. The results showed that hydrocarbon group composition was the primary factor affecting 8 physicochemical properties of blended jet fuel. As the mass fraction of paraffin increased or the mass fraction of naphthene decreased, the 10% recovery temperature, 50% recovery temperature, final boiling point, freezing point, kinematic viscosity at -20 ℃, and smoke point generally decreased monotonically, while density and net calorific value per volume increased monotonically. Hydrocarbon group composition was a non?primary factor affecting the remaining 9 physicochemical properties. An increase or decrease in paraffin mass fraction led to a decrease in flash point and naphthalene hydrocarbon volume fraction, whereas paraffin and naphthene mass fractions had negligible effects on net calorific value per mass, corrosiveness, thermal stability, gum mass concentration, water reaction interface condition, water reaction separation degree, and water separation index. When blending aviation alternative fuels with traditional jet fuel, the physicochemical properties of the blended fuel can be predicted to a certain extent based on the influence rules of hydrocarbon group composition on jet fuel properties, thereby reducing experimental trials and improving efficiency.
Optimal allocation of gas supply reliability is an important part of gas supply reliability of natural gas pipeline system.In order to study the optimal allocation scheme of gas supply reliability with the lowest cost,a cost function model based on the gas supply capacity of the pipeline system was constructed.To address the limitation of traditional intelligent optimization algorithms (e.g.,Particle Swarm Optimization) that overlook constraints during iterative updates,this research proposed a novel Exterior Penalty Function Method for optimizing gas supply reliability.This method transformed constraints in the allocation model into penalty function terms,established a revised objective function,and converted the constrained allocation problem into an unconstrained extremum problem.Applying this method to a practical pipeline system,optimal gas supply reliability allocation values were derived.The results demonstrate that the Exterior Penalty Function Method significantly reduces computational time without compromising accuracy.The allocation outcomes exhibit robust convergence and align with engineering practicality.By clarifying the optimized allocation values of unit gas supply reliability and comparing them with the current reliability,the weak units in the gas supply system can be identified,providing a scientific basis for improving the gas supply reliability of pipeline systems.
The filtration and separation area of a station on the China?Russia East Route is set as parallel pipelines,and the uneven distribution of branch flow may occur due to the differences in internal pressure and pipeline layout,which affects the filtration efficiency and the overall work efficiency.In order to avoid pipeline bias, the flow direction of the filtration and separation area is studied based on computational fluid dynamics (CFD).Results show that pressure distribution, turbulent flow distribution, frictional resistance loss along the system,fluid inertia and other factors affect the branch pipe flow distribution.Among 11 parallel pipeline configurations,the axial inlet and radial outlet configuration (Type 3) with inlets and outlets on the same side exhibits the least flow maldistribution overall.Under normal working conditions,flow maldistribution decreases with increasing manifold diameter and branch pipe spacing within the calculation range.Fault conditions,such as branch pipe blockages,significantly exacerbate flow maldistribution in the system.It is concluded that the flow distribution rule and the main factors affecting the flow distribution are obtained,which is helpful to guide the design and construction of gas transmission station.
Leakage of refined oil pipeline can cause environmental pollution and threaten the safety of residents' lives and properties, making leakage monitoring and identification critical. This study establishes a leakage monitoring and identification model for undulating buried pipelines, generates pressure waves by controlling valve openings, and monitors and identifies leakage locations. The effects of valve opening and valve opening/closing interval time on leakage localization accuracy were analyzed. Results show that the model exhibits high accuracy for identifying medium?sized hole leaks but lower prediction capabilities for small and large holes, resulting in larger relative errors in leakage localization. When the valve opening decreases from 90% to 10%, 30%, and 50%, the amplitude of pressure wave signals decreases, and the relative error in leakage localization calculated by the model gradually increases. A valve opening of 10% is recommended. As the valve opening/closing interval time increases, the relative error in leakage localization grows due to interactions between pressure wave signals and reflected signals, with an optimal interval time of 1 second recommended.
In order to improve the accuracy of magnetic azimuth measurement,it is often necessary to establish a more accurate local geomagnetic model to obtain precise magnetic declination information.Compared with global geomagnetic model, local geomagnetic model contains magnetic anomaly information caused by underground magnetic ore veins at the surface.Considering the different burial depths and sizes of underground magnetic veins,their effects on magnetic declination at different borehole depths differ significantly.Therefore,it is necessary to consider the correction of the azimuth angle of medium and deep wells under the influence of underground magnetic veins.Based on ANSYS Maxwell numerical simulation software,the geomagnetic field model under the influence of magnetic veins of different burial depths and sizes was established.Through numerical simulation method and actual drilled borehole trajectory of a medium?deep well (Z well),a method of azimuth correction was given to quantitatively analyse the influence of underground magnetic veins on the azimuth and borehole trajectory.The results of the study show that the effect of underground magnetic veins on the azimuth of drilling within the 2 000 m thickness stratum is about 0.6° under the condition that the magnetic veins are buried at a depth of 2 100 m.After considering the influence of underground magnetic veins,the borehole trajectory is inevitably offset,and the offset increases with the depth of the well,which may cause off?targeting and other accidents for medium and deep wells.Therefore,it is of great significance to consider that the azimuth correction under the influence of geomagnetic veins can strongly improve the azimuth measurement accuracy and realise accurate guidance.
Indeno[1,2?d]pyridazine derivatives have wide applications in pesticides,pharmaceuticals,and other fields due to their excellent biological activities.Therefore,the development of rapid and efficient synthetic methods for these compounds has attracted increasing attention from researchers.A novel acid?catalyzed cyclization reaction between allylbenzene and tetrazine was designed.Reaction intermediates were trapped,and their structures,along with those of the products,were characterized using nuclear magnetic resonance spectroscopy.The results indicate that the reaction proceeds through intermolecular [4+2] cycloaddition and intramolecular Friedel?Crafts alkylation processes,enabling one?step synthesis of indeno[1,2?d]pyridazine derivatives.The reaction also exhibits a broad substrate scope and good functional group compatibility,yielding a series of indeno[1,2?d]pyridazine derivatives with 67%~95% yields.In gram scale experiments,the target product was obtained with an 81% yield, demonstrating the potential practical value of this reaction.
The propane dehydrogenation reaction is thermodynamically unfavorable, tnecessitating kinetic control through optimized process conditions. Single?factor experiments and multi?factor Response Surface Methodology (RSM) were employed to analyze and optimize propane dehydrogenation conditions over a PtSnK/Al?O? catalyst, followed by experimental verification. First, single?factor experiments determined the range of values for the factors to be studied in the response surface methodology. Then, a Box?Behnken design with three factors (reaction temperature, space velocity, and hydrogen?hydrocarbon ratio) was used to optimize the reaction conditions of propane dehydrogenation by multifactor response surface methodology with propylene selectivity as the response value, and finally, the optimized process conditions were experimentally verified. Results indicated that the optimal reaction temperature, VHSV, and H?/C?H? molar ratio were 605 ℃, 2 200 h?1, and 0.6, respectively. The theoretical propylene selectivity prediction under these conditions was 93.01%. The order of influence weight from largest to smallest was reaction temperature > H?/C?H? molar ratio > VHSV. Experimental verification yielded a propylene selectivity of 93.00% and propane conversion of 32.00%. Experimental determination of propylene selectivity is consistent with RSM predictions, confirming the model's reliability and credibility.
