In order to explore the microscopic mechanism of wax deposition on the pipe wall of high temperature and high?pressure condensate gas wells, this paper uses molecular dynamics simulation technology by the Materials Studio to build condensate oil system with methane, pentane, nonane,n?dodecane, cyclobutane, cyclopentane, benzene and toluene,and the wax component model was built with n?octadecane, and simulate with wax content, asphaltene and scale as variables. The results show that with the increase of wax and asphaltene mass fraction, the wall wax deposition behavior can be intensified, but when the asphalt mass fraction reaches 2.0%,the wall wax deposition behavior can be inhibited.The more kinds of heteroatoms in asphaltene,the more obvious the promotion effect.When there is scale on the pipe wall, sulfate scale has a great influence on wax deposition.The understanding of microscopic mechanism provides a scientific basis for the treatment of wax deposition on the pipe wall.
A novel ruthenium(Ⅱ)?catalyzed C-H/C-N annulation of 1?phenyl?2?pyrazolin?5?one with ethylene carbonate was designed. In this transformation, the vinylene carbonate acts as an ethynol or alkyne surrogate without any external oxidant as well as bases involved. The reaction exhibits a broad substrate scope with excellent functional group compatibility, affording a series of 1H?pyrazolo[1,2?a]cinnolin?1?ones in 42%~87% yields. A possible mechanism involving a sequential C-H activation/intramolecular C-N bond formation/ CO2 or CO
In order to improve the success rate of high temperature and complex formation structural oil wells, the preparative temperature sensitive self?consolidation resin is used to modify the surface of the aggregate material, and the thermally consolidated rigid plug material is obtained, then auxiliaries are chosen to build a novel bridge sealing and thermal consolidation plugging system that could resist temperature to 190 ℃. Infrared spectroscopy, thermal analysis, scanning electron microscopy were employed to study the molecular structure, microstructure and thermal stability of the resin, thermally consolidated rigid plug material and the plugging system, the suspension stability, consolidation rate, consolidation strength and permeability of the plugging system were also investigated. The results show that the constructed plugging system has the advantages of good suspension stability and wide solidification time window in bentonite slurry with mass fraction of 5%, and the compressive strength of the solidified body after curing at 90~190 ℃ are all over 6 MPa; at the same time, the water phase permeability of the solidified body cured at 190 ℃ is 6.32×103 μm2 under the driving pressure of 12 MPa, and the plugging rate is more than 98.00%. It is expected to meet the plugging requirements of high?temperature formation.
In the context of the shipping industry emission reduction target set by the International Maritime Organization and based on the current situation of carbon reduction in the shipping industry, this paper introduces the development history and emission reduction advantages of hydrogen powered ships, analyzes the hydrogen storage methods of hydrogen powered ships at home and abroad and the safety risks of hydrogen energy onboard, and compares the technical advantages and onboard feasibility of various Marine hydrogen storage methods. It is concluded that the hydrogen production technology of shipboard methanol steam reforming is of great significance to solve the hydrogen safety problem of hydrogen?powered ships. At last, the problems faced in developing hydrogen?powered ships with shipboard hydrogen production units are put forward.
As a new type of clean, carbon?free, sustainable and efficient energy source, hydrogen has great potential in the future energy mix. Hydrogen purification by pressure swing adsorption is the main separation technology for hydrogen production with high purity, low energy consumption and high degree of automation. In this paper the progress in research and application of pressure swing adsorption hydrogen production in theoretical simulation, process control optimization and adsorbent materials were critically reviewed, and the future development of pressure swing adsorption hydrogen production technology was prospected.
Establish a metal hydride reactor and test platform, and obtain the corresponding internal temperature and hydrogen absorption/desorption flow data of the reactor under different water bath temperatures, hydrogen release flow rates, and reactor structures (square, honeycomb, and no barriers) through experimental tests to determine The temperature field distribution trends and rules of different reactor internal structures are analyzed. The results show that the square structure reactor has the fastest internal temperature change rate and the best heat exchange effect. The comprehensive performance of the square structure reactor under different hydrogen absorption pressures and hydrogen release flow rates was further studied. The results show that when the inlet pressure is 2.0 MPa to 3.0 MPa, the hydrogen absorption amount and hydrogen absorption rate of the alloy material can be significantly increased; when the hydrogen release flow rate is less than 3.2 L/min, more than 85% of hydrogen can be released. The research results can provide technical guidance for modular and systematic design.
In the methanol autothermal reforming reaction, the required heat is provided by the methanol oxidation reaction, so the activity of the methanol oxidation catalyst directly affects the yield of hydrogen. Pt/γ?Al2O3 catalysts have attracted wide attention because of its high reactivity, but their stability is poor, and the Pt activity center is easy to agglomerate. In order to solve the above problems, Pt/γ?Al2O3 catalysts were prepared by rotary microemulsion, and Pt/γ?Al2O3 catalysts were characterized by BET, XRD and other methods, and the effects of cyclohexane mass fraction, mass ratio of PEG?600 and n?butanol on the oxidation activity of methanol were investigated. The results show that the microemulsion method could improve the dispersion and utilization rate of the active components. By changing the mass fraction of cyclohexane and the mass ratio of PEG?600 to n?butanol, the active component Pt can be uniformly and firmly loaded on γ?Al2O3, and the sintering resistance of the catalyst can be improved. The Pt/γ?Al2O3 catalyst prepared under the condition of cyclohexane mass fraction of 50% and the mass ratio of PEG?600 to n?butanol is 3∶7, and the catalytic activity of methanol oxidation can reach 88%.
Catalysts CuCe?OH and CuCe?CO3 were prepared by hydrothermal method using KOH and K2CO3 as precipitating agents. The catalyst was characterized by XRD, BET, H2?TPR and TG?DTA, and its CO catalytic oxidation performance was evaluated by a fixed bed reactor. The results show that the type of precipitator not only has a great influence on the texture properties of the catalyst, but also determines whether the CuCe catalyst without heterocrystalline phase can be successfully prepared. The specific surface areas of CuCe?OH and CuCe?CO3 catalysts were 96.5 m2/g and 17.3 m2/g, respectively. Under the evaluation conditions of 60 000 mL/（g·h）, CO volume fraction of 0.6%, O2 volume fraction of 1.5%, Ar volume fraction of 97.9%, CuCe?OH catalyst showed good catalytic activity, and CO conversion reached 99.0% at 140 ℃.
As the oil and gas industry strives to find better gas hydrate management methods, it is necessary to better understand the hydrate formation and plugging trend in multiphase flow.The high?pressure visual flow loop is used to study the formation of carbon dioxide gas hydrate and the properties of hydrate slurry under the flow conditions of complete dispersion and partial dispersion system.The results show that for the fully dispersed phase system with high water content, the contact area between gas molecules and water is larger, and hydrate can be fully generated, which has a great impact on the flow in the loop. For the two systems with different water content, because of the oil?water interface in high water content is damaged more violently, a large amount of hydrate is easier to block the loop.The oil?water interface in low water content can be supplemented after being damaged, so the risk of pipe plugging is low.
The infrared radiation observation experiment were carried out in the uniaxial loading process of four sandstones with different water contents. By studying the quantitative relationship between the infrared radiation information and stress of water?bearing sandstone, the influence of water on the infrared radiation characteristics of sandstone was revealed. The results show that with the increase of water content, the size of sandstone infrared anomaly area was larger, and the infrared anomaly phenomenon was more obvious. The mean value of infrared radiation counts of sandstone increased with the increase of the mean value of stress, and there was a linear relationship between them. After fitting the mean value of infrared radiation counts with the mean value of stress, it is found that the slope increases gradually with the increase of water content. The mean value of infrared radiation counts of sandstone was moderately correlated with water content in compaction and elastic stage, and highly linear correlation in plastic stage and post?peak failure stage (correlation coefficient up to 0.96).
In order to study the mechanical properties and microscopic mechanism changes of microcrack propagation of FeNiCu alloy at different temperatures. In this paper, molecular dynamics methods were used to simulate uniaxial tensiles of FeNiCu alloy models containing microcracks and dislocations at 300, 500, 700, 900 K and 1 100 K, respectively. The microstructure evolution of FeNiCu alloys during tensile process was analyzed using Visualization software. Combined with the stress?strain curve and the energy change curve, the micro?mechanism effect of temperature on micro?crack propagation of FeNiCu alloy was emphatically analyzed. The results show that the higher the temperature in these five sets of temperatures, the greater the atomic spacing in the alloy and the more unstable the microstructure. However, the increase in temperature improves the plasticity of the alloy, so that the microscopic defects within it are healed to a certain extent under uniaxial loading, and the mechanical properties are maintained relatively stable. In addition, when the temperature rises, dissociative slip will be strengthened, which aggravates the emission and motion of the dislocation, and the dislocation product will be more likely to form microcracks, so that the dislocation <110> will form microcracks in multiple places in the slip direction.
In the process of metal milling, especially in the machining of low?stiffness workpieces, chatter is a key factor affecting many aspects such as surface quality, machining efficiency and tool life. In order to avoid the chatter, a milling chatter recognition method based on dynamic and Wavelet Packet Decomposition(WPD) is proposed from the signal processing. The modal parameters of the system are obtained by modal experiments. Based on the principle that the chatter frequency will peak near the natural frequency of the system, the original milling force signal is decomposed by WPD, and the sub?signals containing rich chatter information are selected for signal reconstruction. Finally, the time?frequency and Hilbert spectrum characteristics of the reconstructed signal are compared and analysed, and the chatter recognition is performed. At last, the proposed method is verified by the experiments. The results demonstrate the effectiveness and reliability of the proposed method.
In order to solve the problems of short life cycle and low data throughput caused by too fast energy consumption in cluster head node selection of LEACH protocol in wireless sensor networks, a leach optimization algorithm based on cluster head node energy balanced selection is proposed. The algorithm selects ordinary nodes with high residual energy in WSNs as cluster head nodes, and considers the distance between ordinary nodes and cluster head nodes and between cluster head nodes and base station, as well as the residual energy and average energy of all nodes to select communication mode and transmission path. The proposed algorithm is simulated by MATLAB. The simulation results show that in the 100 m×100 m small and monitoring area and 200 m×200 m large and monitoring area, compared with LEACH, DEEC and IMP?LEACH algorithms, the algorithm reduces the energy consumption of nodes in WSNs, prolongs the life cycle and improves the data throughput.
In the field of point cloud processing, deep learning is a mainstream method, but the existing methods do not fully utilize the local structure information of 3D point clouds, and have less local shape perception. We proposes a 3D point cloud processing model based on improved PoinetNet. Network model introduces position adaptive convolution into PointNet. The position?adaptive convolution constructs the kernel function by combining the weight matrices in the weight bank in a dynamic way, in which the coefficients of the weight matrix are adaptively learned from the relative positions of the points through the position?relative coefficient network. The kernel function constructed in this way can better solve the problem of irregularity and disorder of point cloud data. The classification accuracy of the position?adaptive network in the 3D object classification experiment is 3.60% higher than that of PointNet, and the average intersection ratio in the 3D object part segmentation experiment is 2.20% higher than that of PointNet. In the 3D scene semantics In the segmentation experiment, the average intersection and union ratio is improved by 9.14% compared with PointNet.
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