The solidifying point of shale oil is high, and the wax content is high and the emulsification degree of shale oil is high. As a result, it is not easy to dehydrate shale oil emulations by using the traditional thermochemical method, which is difficult to meet the export standard. High frequency pulse dehydration technology is an effective method to dehydrate, but there are few studies on the optimization of treatment parameters of shale oil produced fluid. In this study, the effect of high frequency pulse dehydration technology on Dagang shale oil emulsion was studied, and the treatment parameters were optimized. The results show that high frequency pulse dehydration technology can achieve effective demulsification of shale oil produced liquid and significantly reduce the water content of shale oil. Through the comparison and selection of treatment parameters, it is found that the increase of electric field intensity and electric field frequency is conducive to improve the dehydration efficiency. Besides, there are electric field action time, operation temperature and demulsifier concentration parameters with the best dehydration efficiency. It is proposed that under the electric field strength of 200 kV/m, electric field frequency of 5 kHz, electric field action time of 60 min, operating temperature of 75 ℃, demulsifier mass fraction of 0.010%, the water content of shale oil after dehydration is 0.48%, and the comprehensive benefit is the best. The research results provide technical support for the optimization of shale oil produced fluid treatment parameters.
In order to realize the resource disposal of surplus sludge from sewage treatment plant, ordinary silicate cement was used to solidify it as a building material. The surplus sludge and cement were mixed evenly according to a certain ratio and placed in a standard curing box for 3~28 days. The unconfined compression strength (RC) and total organic carbon (TOC) content of the sludge?cement consolidated body were used as evaluation indicators. It was found that the RC of 28 days for surplus sludge?cement solidified block could reach about 6.9 MPa when mass ratio (Rm) of surplus sludge to ordinary silicate cement and mass ratio (Rl/s) of liquid to solid are 0.63 and 0.31. The RC can't meet the minimum strength requirement of non?sintered brick, but meets the strength requirement for surplus sludge landfill. The total organic carbon value in leached solution (TOCl) of surplus sludge?cement solidified block decreased by about 86% compared with the initial value (TOC0) in consolidated block. It indicates ordinary silicate cement solidified surplus sludge can effectively solidify organics from surplus sludge in the solidified body, which can effectively inhibit the secondary pollution of surplus sludge for land in the landfill treatment process.
In this paper, the method of combining Grand Canonical Monte Carlo simulation and Ideal Adsorption Solution Theory was used to study the adsorption performance of CO2 and CH4 on NaX zeolite. By comparing the fitting results of simulation data under different adsorption theoretical models and calculating the adsorption heat, a description of the adsorption and separation process of CO2 and CH4 gas was obtained. The results show that the adsorption strength of CH4 molecules is weaker than that of CO2 molecules, and its adsorption is closer to the ideal adsorption. The adsorption selectivity of CO2 molecules is decreases with the increase of its content in the air, and decreases with the increase of temperature under low pressure conditions. Therefore, low temperature and low pressure are more conducive to the separation of CO2 molecules.
In this paper, the extraction process of flavonoids from Ligusticum was optimized by single factor test and response surface methodology, and the antioxidant experiment in vitro was carried out. The optimum extraction conditions were as follows: extraction time 2.5 h, extraction temperature 83 ℃, ethanol concentration 84%, liquid?solid ratio 35 L/g (the ratio of ethanol volume to Ligusticum jeholense powder sample mass). Under these conditions, the yield of flavonoids from Ligusticum was (22.64±0.18) mg/g. The results of antioxidant experiment in vitro showed that flavonoids from Ligusticum had certain antioxidant capacity. The clearing effect of ·DPPH is the best, the clearing effect of ·OH is the second, and the clearing effect of·O2- is the worst. It also has the ability to restore Fe3+.
In this study, nano?TiO2 was used as the additive phase, and B2O3 and H3BO3 were doped in a certain proportion, and then 4% nano?oxide particles reinforced Al matrix composites were prepared by high?energy ball milling and powder metallurgy. Finally, Al matrix composite rods were prepared with an extrusion ratio of 16∶1 at 723 K. The results show that the dispersion distribution of nano?oxides in Al matrix can be realized after 4 h ball milling. After vacuum hot pressing at 893 K, the addition phase reacts with the Al matrix in?situ and forms Al2O3 etc. When the molar ratio of Ti to B is 1.0∶1.5, the mechanical properties of the composites are the best. At the same time, when the chemical composition of the precursor of B element is different, the mechanical properties of the composites are significantly different; the tensile strength of TiO2+H3BO3/Al at room temperature and 623 K is 507.7 MPa and 151.3 MPa, respectively, showing the highest room temperature mechanical properties; the tensile strength of TiO2+B2O3/Al at room temperature and 623 K is 353.7 MPa and 167.1 MPa, respectively, manifesting the excellent high?temperature mechanical properties.
Proton conductive materials are an important part of sensors and fuel cells. In recent years, the research of crystalline proton conducting materials has mainly focused on metal organic framework material(MOF). Lanthanide metal organic framework (Ln?MOF) is an important member of the MOF family, and it is easy to form a stable and diverse framework owing to the strong coordination ability, Lewis acidity and complex functionality of lanthanide ions. At present, people are beginning to focus on its research in the field of proton conduction. This article reviews the research progress in proton conduction of Ln?MOF materials with different functional acid groups (carboxylate, phosphonate or sulfonate groups, etc.) introduced into the main frame. The challenges faced by Ln?MOF materials in the study of proton conduction were prospected.
Most of the oil fields in China have entered the middle and late stage of exploitation, and the well produced fluid has a high water content. FRP pipes are widely used in surface gathering system of oilfield because of their excellent corrosion resistance. At the same time, in order to save heating energy, low?temperature transportation process can be used to transport high water?cut crude oil, but the possible adhesion problem of crude oil is a serious threat to system safety.Therefore, it is important to investigate the interfacial properties of FRP pipe wall/crude oil to reveal the adhesion mechanism of low?temperature transportation of crude oil with high water?cut. The interfacial properties of crude oil on the FRP surface and stainless steel surface were investigated based on the contact angle apparatus. In the aqueous phase, the contact angle of oil droplet on the solid surface increased with decreasing temperature, and the contact angle of oil droplet on the FRP surface is larger than that on the stainless steel surface. The interfacial tension of oil droplet increased with decreasing temperature in the aqueous phase, and compared to the stainless steel surface, the adhesion work of oil droplet on the FRP surface is lower. And the cohesion work of oil droplet decreased with increasing temperature in the aqueous phase. Crude oil is not easy to adhere to the FRP pipe in the gathering system, FRP pipe is more conducive to the implementation of low?temperature transportation process.
Standalone screen sand control method is one of the most commonly used sand control method for oil and gas wells. With the deepening of oil and gas field development, the working environment and its own conditions of the independent screen sand control system have changed. Affected by high temperature and high pressure, external load, corrosion, fluid erosion and other factors, it is easy to cause sand control failure, which seriously affects the normal production of oil and gas wells. In this paper, long?term mine practice and theoretical analysis are taken to investigate the reasons for sand control failure. It is considered that the main causes of sand control failure are sand control packer failure, sealing mechanism failure and sand control screen tube failure, among which sand control screen tube failure is the most likely to occur. Screen erosion, screen corrosion, geological factors and special operations are the main factors leading to the failure of sand control screen. Through the in?depth analysis of the causes of sand control failure in oil and gas wells, it provides an important basis for taking preventive measures to avoid sand control failure and affecting production.
Aiming at the problem of wax deposition in gas well exploitation of offshore HPHT gas reservoir, the gas?liquid?solid and fluid phase equilibrium theory and method of throttling effect principle was used to reveal the wax deposition mechanism of the abnormal high temperature and high pressure gas well, and it was found that wax deposition in high temperature and high pressure gas wells mainly occurs at the position of the oil nozzle where the temperature drops sharply when the wing valve of the gas well is closed. According to the phase equilibrium theory, the phase state of the original formation fluid in HPHT gas well was recovered and characterized, and the phase state change characteristics of gas?liquid?solid three?phase fluid, wax precipitation mechanism and process were described accurately. Based on the phase equilibrium model, the wax location, fluid composition change and the influencing factors of wax deposition were analyzed. It was reasonable to explain that the mechanism of wax precipitation in HPHT gas well is the transient phase transition from gaseous to liquid and then to solid due to the rapid change of temperature and pressure, and the corresponding prevention and control strategies are put forward.
For the under?expansion jet generated after the failure leak of high?pressure pipeline, the Birch theory model was used to replace the actual pipeline leak hole with a pseudo?source. Under different conditions of Hydrogen Blend Ratio (HBR), leak hole size and pipeline running pressure, the concentration field distribution, explosion hazard boundary and explosion hazard range of hydrogen?doped natural gas pipelines after leakage and diffusion were studied. The results show that with the increase of HBR, the aggregation of HDNG after leak diffusion is reduced, the explosion hazard range is gradually decreased and the distal hazard is reduced. However, the increase of HBR shifts the position of explosion hazard boundary downward and increases the proximal hazard. With the increase of leak hole size and pipeline pressure, it will increase the influence area of HDNG after leak diffusion, which will move the explosion hazard boundary position upward and increase the explosion hazard range gradually and increase the distal hazard.
This paper proposed a method to improve the safety of shell and tube heat exchangers by adding a heat insulation layer at the inlet end of the heat exchange tube. Based on the SIMPLE algorithm, the transient change model of end temperature difference of three?dimensional shell and tube heat exchanger was established, and the effects of the changes of insulation thickness and insulation material on the safety of heat exchanger were compared. The results show that the temperature difference between the two sides of the heat exchange tube is significantly reduced when the pipe end insulation layer is installed, regardless of the material of the pipe end insulation layer; The greater the thickness of the insulation layer at the pipe end and the thermal conductivity of the insulation material, the greater the reduction of temperature difference, instantaneous thermal shock stress and temperature difference thermal stress on both sides of the heat exchange tube, and the higher the safety of the heat exchanger; When the thickness of the pipe end insulation layer is 247.5 mm and the thermal conductivity is 2.090 0 W/(m?K), the maximum instantaneous temperature difference on both sides of the heat exchange pipe can be reduced by 10.1%, the maximum temperature difference can be reduced by 12.5% during stable operation, and the instantaneous thermal shock stress and temperature difference thermal stress can be reduced by 10.1% and 12.5%.
The data acquisition and modeling of the depressed pipe were carried out using a 3D scanner, and the residual strength at the depressed pipe was evaluated; based on the modeling, the finite element analysis of the 3D modeled pipe containing the depression was carried out using ABAQUS software, and the stress?strain analysis was carried out using numerical simulation; the geometric deformation detection method was used to detect the depressed pipe, and the stress?strain at the depressed pipe was calculated and analyzed. The load?bearing capacity of the recessed pipe was evaluated; a comparative analysis was conducted for both cases of the pipe with/without internal pressure. The results show that the maximum Von Mises stress at the depression differs greatly between the two cases with/without internal pressure; in the case with internal pressure, the maximum Von Mises stress is located at the perimeter of the pipe depression rather than at the depression; in the case with internal pressure, the maximum equivalent force in the area near the depression is 22.6 MPa, while the maximum equivalent force in the case without internal pressure is 14.8 MPa. The maximum Von Mises stress applied to the pipe is distributed in the deepest part of the depression with a value of 710.3 MPa, and the maximum equivalent force becomes 8.99%, which is distributed in the inner part of the depressed pipe when the downward displacement constraint of 50 mm is set in the indenter. In engineering applications, the 3D scanning technology can be used to obtain the contour of the pipe depression more quickly, and the output data can be used to provide technical support for subsequent stress?strain analysis, pipe evaluation, and rehabilitation.
Aiming at the low efficiency of Apriori algorithm in scanning database and low dimensional frequent itemset, an efficient implementation method of Apriori algorithm was proposed, which is called EI_Apriori algorithm. This method utilizes the vector?based storage structure and pre?pruning to reduce the number of scanning databases and low?dimensional frequent itemsets and thus improves the efficiency of the Apriori algorithm. According to the actual situation of student achievement analysis, the constraints on the sequence relationship between courses are added in the association rule mining, and the constraints on the score level range are added in the association rules. The adjusted EI_Apriori algorithm was applied in score association analysis. The results show that the EI_Apriori algorithm can accurately find the association rules that meet the real needs, which proves the superiority of EI_Apriori algorithm.
Aero?engine usually contains a large number of pipes, the arrangement sequence of these pipes has a certain impact on the overall layout effect of the system. In order to reduce the degree of cross layout of multiple pipes, the evaluation method of pipe disassembly complexity was designed based on product assembly and disassembly, a Discrete Chicken Swarm Optimization (DCSO) algorithm was used to solve the pipe layout sequence planning. First, a calculation method of pipe disassembly complexity was proposed to evaluate the complexity of pipe system layout scheme. Next, the pipe was pre?planned by A* algorithm. Then, an obstacle avoidance algorithm was designed based on engineering rules to adjust the pipe. Finally, taking the pipe length and disassembly complexity as the optimization objectives, the pipe layout sequence was optimized based on DCSO, and the feasibility of the proposed method was verified by a layout example.
For a long time, researchers mostly analyze the transmission process of infected nodes in complex networks to get the target of forecasting and arresting the extend of the infectious diseases. In this article, the SEIR propagation dynamics model was extended to the undirected and powerless large small world network, and the weights between nodes were given as infection ability. Two initial node selection methods were selected to carry out multiple simulation experiments. Based on the traditional method of judging the impact of transmission by the number of infected people and infection threshold, the specific values of infection probability, peak value and inflection point time were added to analyze the impact of initial node selection on transmission process more comprehensively. The compared experimental results show that the initial node which the degree is larger and the betweenness is larger, the larger the propagation scale, the faster the propagation speed and the shorter the equilibrium time. This study provides some reference value for guard against and control of the extend of infectious diseases.