Ppb amount of SO2 in air will react with cathode material of solid oxide fuel cell, inducing decrease of the cell/stack performance as one of the most effective factors.The sulfur poisoning behavior of (La0.6Sr0.4) (Co0.2Fe0.8)O3(LSCF) and A?site deficient (La0.6Sr0.4)0.85(Co0.2Fe0.8)O3(LSCF85) was investigated after exposure to 30 μg/g SO2 at 800 ℃ for 50 h.The products of the reaction were characterized by XRD,SEM and EDX to evaluate the effect of A?site defects on the sulfur poisoning behavior of perovskite ferrite based solid oxide fuel cell cathode materials. It was found that A?site defect in LSCF85 can suppress the chemical reaction between LSCF based cathode and SO2. It was ascribed to the low Sr reaction activity with SO2 caused by the existence of A?site defect.
Oxime exchange is a novel process preparing acetaldehyde oxime, but some disadvantages in the reaction process also exist, such as easily oxidized acetaldoxime by air, many azeotropes in the reaction solution, and hardly separated and purified acetaldoxime.The oxidation of acetaldehyde oxime and volatilization of acetaldehyde and butanone oxime were avoided using 0.2 MPa nitrogen as protective gas during the reaction process. The selectivity of acetaldehyde oxime is 96.12%. Moreover, an effective purification process of the product was developed. Firstly, the basic process of separation of reaction liquid by vacuum distillation was simulated by Aspen plus. The influences of pressure, plate number, reflux ratio and feed position on the separation process were investigated. According to the operating parameters of simulation, the optimum separation and purification process in actual reaction were determined. In this condition, the purity of the resulting acetaldoxime is 95.33% with the yield of 94.31%. This work could provide guidance for the industrialization of acetaldehyde oxime by oxime exchange method.
Industrial wastewater is mainly composed of sewage and waste liquid produced in industrial production process, which has been characterized by its complex composition, wide variety, large difference and difficulty in treatment.The commonly used methods for preparation of hydrotalcite were reviewed, such as chitosan method, plasma method and agricultural waste method. Hydrotalcite materials in the adsorption process are mostly in powder, which is difficult to be recycled, and rarely used in industry applications. In view of the above problems, Fe ions can be introduced in hydrotalcite materials to generate magnetism, which is be beneficial to recovery. By developing cheaper synthetic materials, simple and fast preparation methods, stable physical and chemical properties of hydrotalcite materials, industrial applications could be achieved. The introduction of magnetic materials into hydrotalcite composites can help to recycle. With the in?depth study of hydrotalcite preparation technology, the prospect of dealing with toxic pollutants will be better.
The spherical hexagonal phase tungsten oxide (h?WO3) was synthesized by precipitation method. Then a series of hexagonal/monoclinic WO3(h/m?WO3) phase junction photocatalysts were controllable fabricated by regulating the phase transition process from hexagonal to monoclinic phase. The crystal phase structure and phase composition, particle size and specific surface area of these WO3 catalysts were characterized by X?ray diffraction (XRD), scanning electron microscopy (SEM) and specific surface area (BET). The experimental results of photocatalytic O2 evolution show that compared with the pure hexagonal phase WO3, the h/m?WO3 with suitable crystal phase composition exhibits remarkable photocatalytic performance. Based on the band positions of hexagonal and monoclinic phases, the surface photovoltage (SPV) characterization results show that the formation of h/m?WO3 phase junction significantly promotes the efficient separation of photogenerated electrons and holes on the surface of the catalyst, and then improves the photocatalytic activity of WO3 catalyst.
The photocatalysis technology becomes more and more mature. As a non?metallic visible light responsive catalyst, carbon nitride (g?C3N4) has attracted wide attention in the field of solar energy conversion and environmental protection due to its adjustable band gap structure, high physicochemical stability and environmental friendliness. It has become a new research hotspot. However, g?C3N4 also has some defects, such as small specific surface area, recombination of photogenerated electron and holes, and low utilization rate of light energy,which limit the application of g?C3N4 in practice.Therefore,the review focus on the development and research results of g?C3N4,and summarizes g?C3N4 from the aspects of development process,synthesis method, performance application,modification and optimization,and predicts how to further improve the performance of g?C3N4 to cope with the future development of the world.
As a loose sandstone reservoir, PL oilfield has been characterized by its strong velocity sensitivity,long oil?bearing intervals,multiple oil?bearing sequences and complicated sedimentary types.Due to the previous failures of earlier application,horizontal well has always been considered to be not suitable for PL oilfield.Based on the micro reservoir characteristics of PL oilfield in Bohai Sea,the evaluation technology of horizontal well in loose sandstone and the classified development technology of combined well pattern in thick thin multi?layer reservoir are studied by means of seepage theory,numerical simulation and field practice.The results indicates that,the unit area velocity of the cylinder hemispherical combination seepage area of the horizontal well is far less than that of the cylinder seepage area of the directional well in the near well zone.The field test data proves that horizontal wells have more advantages in resisting velocity sensitivity in unconsolidated sandstone reservoirs.The interference between directional well and horizontal well in the combined well pattern of multi?layer thick thin reservoir is compared.It is proved that whether the formation energy is sufficient or not is the main controlling factor of inter well interference in the combined well pattern during the period of middle and high water content.
In order to explore the water displacement efficiency and its influencing factors of high porosity and high permeability unconsolidated sandstone heavy oil reservoir through the thermal production boundary in the mode of large volume liquid extraction and cold production,taking LD oilfield in Liaodong mining area of Bohai Sea as an example, the systematically study on oil displacement efficiency of 2 000 PV high multiple water was carried out with flow rates were 1.0,7.5,15.0 mL/min.At the same time,combined with mercury injection,X?ray diffraction,whole rock and gas permeability measurement,the liquid extraction system can be optimized,and the influence of various factors on the water oil displacement efficiency of this type of heavy oil reservoir after liquid extraction was analyzed as well.The experimental results show that the differences of reservoir geological characteristics such as micro pore?throat structure,interstitial content and permeability have a great influence on the displacement characteristics after liquid extraction. The worse micro pore?throat structure would induce a higher the interstitial content, inferior permeability and lower high PV water flooding efficiency.Compared with the direct liquid extraction method, the step?by?step liquid extraction method can achieve higher water flooding efficiency.For this type of heavy oil reservoir,it has the best liquid extraction range.If the amplitude is too large, it is easy to cause the front edge to burst, and reduce the micro sweep. It should be controlled at 7.5 times. The experimental results can effectively guide the exploitation of residual oil by using horizontal well extraction in heavy oil reservoirs.
In order to explore the water control mechanism of buried hill crack reservoir section, taking Huizhou 26?6 condensate field as an example,the fracture gas reservoir water control physical experiment model,equilibrium gas water interface and piecewise water control experiment evaluation were established,through designing the experimental parameters,buried hill crack formation and water control process.The results show that the segmented water control can effectively prolong the water?free gas production period and delay the water breakthrough time to a certain extent.The different combination of crack and horizontal well section would induce diverse gas production characteristics.Coupling between horizontal well subsection water control and gas reservoir seepage was a complex process.The matching between blind pipe section and production section directly affects the gas well productivity.The opening degree of production section,the length and the location of blind pipe section are the main factors affecting the productivity of fractured gas reservoir.The research results will establish a sublevel water control development model for buried hill gas reservoirs and provide good technical support for rational and scientific research on water control of horizontal wells in offshore condensate gas fields.
During the thermal recovery of steam injection in heavy oil reservoirs, once steam channeling occurs between wells resulting in ineffective steam circulation, which seriously restricts the expansion of steam sweep volume and the improvement of oil recovery. A 2D visualization experimental apparatus was used to research the phenomenon of steam channeling and the distribution characteristics of remaining oil during steam injection in heavy oil reservoirs. Then, the method of numerical simulation was used to research the influence factors of steam channeling between wells. The results showed that steam migration is a process of steam driving condensate water and water driving oil in porous media. Outside the displacement front, the reservoir temperature gradually decreases and the seepage process presents the characteristics of conventional non?piston water flooding. The seepage speed of water is faster than that of crude oil, which results in an obvious inrush phenomenon and a lot of remaining oil on both sides of channeling path. Finally, the plane sweep efficiency in only 43.16% between injector and producer. However, there is amount of residual oil in the swept zone of steam injection. The main influence factors include the relationship between well location and high permeability zone, the plane heterogeneity, the thickness, the oil viscosity, the speed of steam injection, and etc.
Layered water injection tool is the core part of layered water injection system,which is of great significance to the development of layered water injection technique.In order to study the influence of different pipeline roughness and flow rate on friction and pressure consumption of crossing bridge short joints of layered water injection tools,Fluent software is used.The simulation results show that the flow rate of crossing bridge short joints of layered water injection tool is 500~2 000 m3/d,the pressure consumption range of the outer pipe is 1.90×104~6.61×105 Pa,and the pressure consumption of the inner pipe is 3.61×105~4.03×106 Pa.When the roughness is constant,the larger the liquid flow would induce greater the local resistance and the greater the friction pressure consumption of the layered water injection tool.The effect of pipeline roughness on friction and pressure loss is small and can be ignored.The above research results can provide the basis for the design and parameter selection of the new layered water injection pipeline.
In view of the characteristics of low porosity, low permeability,high temperature and high salinity of reservoirs in block M of Daqing Oilfield,conventional surfactants cannot achieve good oil displacement effect.Therefore,a new type of surfactant SZ?11 was synthesized using maleic anhydride,ethylenediamine and long?chain alkyl bromides as monomers,and then mixed with non?ionic surfactant AEO?3.A new oil displacement system with higher temperature and salt resistant suitable for low permeability reservoir is formed,and its performance is evaluated.The results show that the prepared oil displacement system has good temperature and salt resistance.After aging at 140 ℃,the interfacial tension can still reach 0.008 mN/m.The system still has low interfacial tension in high concentration of sodium chloride (150 000 mg/L),calcium chloride (9 000 mg/L) and magnesium chloride (2 500 mg/L); the oil displacement system also has good emulsifying performance and wettability. The oil displacement efficiency can be improved by emulsifying crude oil and changing the wettability of rock surface. The oil recovery of reservoir core can be increased by 19.5% by injecting 0.4 PV prepared surfactant after water flooding step.The field application results show that after surfactant injection,the daily oil production of 5 production wells in block m is significantly increased,the water content is decreased, and better oil production increase effect is achieved.
Foam drainage gas recovery is the main drainage gas recovery process in Changqing gas field,some of the foam has not been defoamed after reaching the surface pipeline.Auxiliary defoaming agent is needed to reduce the damage of foam to the gathering and transportation system. Foam drainage gas recovery process is the main drainage gas recovery process in Changqing gas field at present. Some foam still fails to defoam after reaching the surface pipelines, so auxiliary defoaming agent is needed to reduce the damage caused by foam to the gathering and transportation system.Because of liquid defoamer has short action time,poor defoaming effect and low degree of automation,the application of solid defoaming device has been increased in Changqing gas field recently,but the supporting solid defoaming rod has high cost and poor applicability, which leads to the non?obvious defoaming effect and seriously restricts the popularization and application of the process.According to the water quality characteristics of Changqing gas field, dimethyl silicone oil and gaseous silica particles were used as raw materials to make silica paste, sucrose as curing agent and S?185 as emulsifier. After melting reaction, solid defoaming agent DFS?1 was produced after cooling.Q/SY 17001-2016 technical specification for defrosting agent for foam drainage gas recovery was adopted to test its performance. The defrosting time was 12.1 s and the bubble suppression time was longer than 10 min. The comparison test of simulated formation water shows that all the performance parameters meet the requirements, which can meet the field application requirements of Changqing gas field.
Mixing hydrogen into natural gas pipelines for transportation is an effective way to achieve large?scale,long?distance, and low?cost transportation of hydrogen.However, the mixing of hydrogen will have a great impact on the hydraulic characteristics and safety of natural gas pipeline during transportation.In this regard,SPS software was used to simulate the transportation and leakage conditions of natural gas pipelines with different hydrogen mixing ratios, in order to investigate the effects of hydrogen mixing on the hydraulic characteristics of natural gas pipelines,the operating characteristics of centrifugal compressors,and the pressure drop rate of block valve and leakage after leakage.The results show that adding hydrogen will reduce the gas transmission efficiency of the natural gas pipeline network and compressor performance,which can be compensated by increasing the pressure drop.The dynamic pressure amplitude decreases with the increase of hydrogen mixing ratio under the same natural gas output.When the hydrogen mixed natural gas pipeline leaks,the pressure drop rate and the leakage would increase as the increasing of hydrogen mixing,and the set value of the pressure drop rate threshold of the pipeline block valve also increases accordingly.In conclusion,the research results in this work can provide the basis for the research on determining the maximum of hydrogen mixing ratio in the natural gas pipeline and provide a reference for the determination of hydrogen mixing transportation technology in natural gas pipelines.
With the increasing requirements of the sealing industry and the development of the industry, the design and manufacturing technology of mechanical seals is one of the most important key objects in the field of fluid transmission and control. Besides，higher requirements of the development of mechanical seals was also put forward. In order to promote the development of mechanical seal technology, the paper briefly introduces the future development of mechanical seal from the perspective of solving the problems of mechanical seal.The main development trends of mechanical seals are point out, such as higher sealing performance under extreme working conditions, service life and stability under conventional working conditions. In view of controllable mechanical seal, combination of mechanical seal intelligence and seal will become the development trend of mechanical seal in the future.
