Photocatalytic technology can convert solar energy into chemical energy under mild reaction conditions and promote the degradation of organic pollutants. As a new type of non⁃metal semiconducting polymer, graphite phase carbonitride has unique electronic structure and good chemical stability. In recent years, it has received extensive attention in the field of photocatalysis, but graphite phase carbonitride itself has some shortcomings. However, graphite⁃phase carbon nitride itself has some shortcomings, for example, the forbidden band width is 2.7 eV, which can absorb only blue⁃violet light of less than 475 nm in sunlight, photo⁃generated carriers are easy to recombine, quantum efficiency is low, and specific surface area is small, which needs to be modified to improve photocatalytic performance. In this paper, the research progress of graphite⁃phase carbon nitride in structure optimization, precious metal deposition, semiconductor composite, element doping, dye sensitization, carbon composite and its application prospect in the field of environmental pollution purification are reviewed.
ZSM⁃5 molecular sieve was used as carrier, cerium (Ce), manganese (Mn), nickel (Ni) and copper (Cu) were used as active components to prepare metal⁃supported catalyst to catalyze ozonation treatment of phenol wastewater. The catalyst was prepared by impregnation method and characterized. The effects of active components, ozone dosage, catalyst concentration and pH on the treatment of phenol wastewater were investigated. The results showed that Ce⁃ZSM⁃5 had the best catalytic effect and COD removal rate under the conditions of pH=7, catalyst concentration of 1.00 g/L, ozone dosage of 44.0 mg/min and reaction time of 60 min. It is 85.74%. When Ce⁃ZSM⁃5 is added, about 80% of the ozone can be saved. It shows good stability which the COD removal ratio reached about 70% after the catalyst repeatedly used for 7 times.
Synthetic technology of anthraquinone (AQ) and its derivatives in the past ten years was reviewed. The process conditions of anthraquinone production from anthracene (AN) by oxidation and phthalic anhydride were described in detail. The mechanism of anthraquinone oxidation by anthracene oxidation was analyzed. The application of one⁃step and two⁃step synthesis of ruthenium catalyst from phthalic anhydride was introduced. Especially, the application and development of zeolites and strong acidic ionic liquids as catalysts was introduced in the anthraquinone synthesis process by one⁃step or two⁃step, and have suggestions for the development of future antimony synthesis processes.
The flavonoids from lactuca tatarica were extracted by solvent⁃extraction method. The optimum extraction condition was determined by single factor experiment combined with the RSM. The results showed that the optimum extraction conditions for Mengshan lettuce were ethanol volume fraction of 70%, liquid⁃solid ratio of 40 mL/g, water bath temperature of 74 ℃, water bath time of 3.2 h. Under this condition, the actual yield of flavonoids was 37.06 mg/g (dry weight), which was very close to the prediction value. The model can simulate and forecast the yield well. This experiment provided the theoretical basis for actual production operation.
Using the OP⁃10 and L61 emulsifiers to configure different hydrophilic equilibrium values (referred to as the HLB),the viscosity test of heavy oil in the second area of the oil production plant of liaohe oilfield was carried out to find out the optimal HLB of the heavy oil.At the same time, FBRM was used to measure the viscosity of heavy oil, and the effect of droplet quantity and particle size on viscous oil viscosity was analyzed.For further study on the viscosity change mechanism of heavy oil emulsion, it can be used to provide reference for the process of heavy oil reduction.Test results show that:the HLB of the emulsifying agent added to the heavy oil emulsion was 9.0,the effect of viscosity is best.At this time, the number of droplet drops to stable, compared with other HLB emulsifiers, the quantity of emulsifier is obviously low, the droplet is evenly distributed and the emulsion is stable.
Introduces a kind of compound ferrous sulfide cleaner, the principle to use the coordination reaction and oxidation and reduction reaction to the ferrous sulfide removal equipment. Respectively in different complex agent and oxidant ferrous sulfide removal, according to the result of single factor experiments, chose the sodium pyrophosphate and sodium hypochlorite as the main composition of cleaning agent, use the orthogonal experiment to investigate the concentration of sodium hypochlorite, sodium pyrophosphate mass, cleaning time and cleaning temperature effect on the clearance of ferrous sulfide. The experimental results show that when the concentration of sodium hypochlorite is 0.003 mol/L, sodium pyrophosphate mass is 1.5 g, cleaning temperature is 80 ℃ and the time is 12 h, the clearance rate of ferrous sulfide is highest, at 75.0%.
As the main flocculant of flue gas desulfurization wastewater treatment, polyaluminium chloride has the problems of large dosage and high cost in application.By observing the clarity of sewage and determining the concentration of pollutants in sewage, the flocculation effect of polyaluminium chloride, polyacrylamide with different molecular weight and their combination on flue gas desulfurization sewage from catalytic cracking unit is studied by spectrophotometry and chemical titration. The results show that the flocculation of polyaluminium chloride and polyacrylamide was superior to the flocculation of polyacrylamide alone, and the larger the relative molecular mass of polyacrylamide, the better the flocculation effect. At the same time, the effects of flocculant dosage, sewage pH value and stirring time on the flocculation effect were analyzed and optimized. The results showed that 30 mg/L polyaluminium chloride and 1.0 mg/L ultra⁃high molecular weight polyacrylamide were the best flocculation effect on catalytic cracking flue gas desulfurization wastewater at pH 7~8 and stirring time 4~6 minute. The research results also laid a solid foundation for the cost optimization of sewage treatment in the future.
Firstly, the effect of the mechanical centrifugal purifier rotation speed on its own resistance in the case of using a mechanical centrifugal lampblack purifier alone was studied. Secondly, the effect of the mechanical centrifugal purifier rotation speed on the cleaning cycle and the soot purification efficiency of the electrostatic fume purifier was studied under the combined use of the mechanical centrifugal purifier and the electrostatic fume purifier. Finally, in order to optimize the equipment, we will extend the metal mesh turntable coating of the mechanical centrifugal purifier to extend the cleaning cycle of the mechanical centrifugal purifier, and study the friction coefficient of the mechanical centrifugal purifier after coating on the self⁃purification efficiency and the purification efficiency of the whole system influences.The results show that the use of mechanical centrifugal purifier can prolong the cleaning cycle of electrostatic fume purifier. The use of electrostatic fume purifier can improve the purification efficiency of mechanical centrifugal purifier. The combination of a mechanical centrifugal purifier and an electrostatic fume purifier has the best effect on the purification of the fume.
Aiming at the serious pollution caused by burning of the fossil fuel, to increase the proportion of clean energy in primary energy consumption in China, a new Organic Rankine Cycle system utilizing the solar energy and the cold energy of liquefied natural gas (LNG) was constructed to solve the problem of serious environmental pollution caused by fossil fuel combustion. The results showed that: the optimal net output power and thermal efficiency were obtained when the two cycle take the best evaporation pressure 2.8 MPa and the best evaporation temperature 371 K, the values are 81.46 kW and 20.88% respectively; when the evaporation pressure of two cycle is 3.0 MPa and the evaporation temperature is 371 K, the exergetic efficiency reaches the peak value 53.43%; the maximum exergy loss of the system is in the heat exchanger components, the exergy efficiency of solar collector is lower. According to 90% power generation efficiency and 1 yuan/(kW·h) electricity price, the system can bring economic benefits of more than RMB 530 000 per year. Compared with the same coal⁃fired power generation, it has the effect of SO2 emissions by 13 939 kg/a and CO2 emissions by 462 000 kg/a, which can achieve the effect of energy saving and emission reduction.
The effect of temperature on corrosion behavior of 316L stainless steel (316L SS) in 3.5% NaCl solution was studied by potentiodynamic polarization and electrochemical impedance，the semiconductor properties of the passivated film were analyzed by Mott⁃Schottky curve. The surface morphology of 316L SS after corrosion was observed by metallographic microscope.The results show that in the NaCl solution with a mass fraction of 3.5%, the open circuit potential and corrosion potential of 316L SS gradually decrease with the gradual increase of temperature, and the self⁃corrosion current density increases gradually.And the pitting potential is also gradually reduced. The results of surface corrosion morphology observation showed that the number and diameter of corrosion pits on the surface of 316L SS increased as the temperature increased.This is mainly because the temperature decreased the density of the passivation film and increased the dissolution rate of the passivation film, and decreases the corrosion resistance.
Because of Gas drilling’s distinguishing feature, drilling tool is wornouted seriously by high velocity liquid’s erosive action and drilling tool substitute thread is cracked easily by air hammaer upward’s shock wave, all of which impact drilling speed and increase drilling cost. Based on the theory of rock mechanics and gas/solid two⁃phase flow, drilling tool erosived by liquid in gas drilling is analysed, return velocity model of mixture in annular is established, return velocity in annular impacted by back pressure is calculated with illustration. In order to avert erosiving by high velocity, return velocity of mixture in annular has to be between minimal carrier velocity and interface erosive velocity. Increasing well head back pressure could decreased the drill tool’s erosiving. Based on mechanical theory，the deformation harmonization equation of drilling tool substitute thread under the influence of pretightening load is fetched. The stress of drilling tool thread is analysed by finite element. The screw thread load distribution regular pattern of drilling tool substitute thread is found out. The thread stress centralized area is obtained, which could provide measure to prevent drilling tool failure and to enhance thread strength.
Urban gas pipeline network is mostly laid underground, which brings difficulties to detecting small leakage.After the leakage,it is prone to poisonous accidents such as poisoning, fire, explosion, etc., which brings hidden dangers to urban public safety.This paper sets up a calculation model for two backfilling methods of layered soil and non layered soil in pipe network,and different physical convection diffusion models are established for different laws of gas diffusion in soil and atmosphere environment.Based on the unsteady leakage model and the CFD software, the paper analysis the buried duffusion separately and analysis the atmospheric diffusion coupling soil and atmosphere.And the study about the effect of back filled soil on the diffusion of gas in soil and atmosphere.The results show that:low⁃ and medium⁃ concentration gas will delay diffusion and produce inflection point through stratified interface. The diffusion rate will increase after the layered interface, and the diffusion rate of gas in the layered soil will be high when the leakage time is greater than 100 s.The atmospheric diffusion rate of methane under stratified soil is not much different between the upwind side wind and the downwind directions. The longitudinal 100 s diffusion rate is larger than that one of the non stratified soil, and the larger the inertial resistance coefficient is, the faster the diffusion is.
In order to reduce the hazards caused by the severe slug flow in the mixed pipeline, it is necessary to analyze and study its flow characteristics. Taking the experimental system of a horizontal downdip tube⁃catenary riser in some literature as the research object, the relevant mathematical and physical models are established. The CFD software is used to simulate the serious slug flow in this type of pipe, and the characteristics of the severe slug flow and the variation of pressure, velocity and gas content are analyzed.The flow pattern map is obtained by numerical simulation with different inclination angles, pressure curve and cycle variation analysis show that with the increase of the slope angle of the pipeline, the flow pattern map conversion boundary changes, the formation of severe slug flow to the superficial gas velocity increases, forming the intermittent flow to the superficial gas velocity decreases the maximum value; the maximum value of the severe slug flow pressure changes little with the tilt angle, and its period decreases with the increase of the tilt angle, and changes exponentially.
Great damage in environment can be caused by pipeline leakage, the explosive oil pool and cloud of steam explosive will cause serious casualties and economic losses, domestic and foreign scholars have conducted a lot of research on the danger of oil pipeline leakage, but the petroleum pollutants migration laws are restricted by specific environmental conditions, therefore, the relationship between pollutant migration migration laws and the factors affecting its diffusion effect has became the most important research direction. Explosion of oil vapor cloud is heavy gas diffusion, The diffusion range is concentrated in the near ground and is greatly affected by environmental factors. The simulation study confirmed that the TNO multi⁃energy method is more suitable for the outdoor explosion evaluation of open fire than the TNT equivalent method, and the steam cloud of different components has different hazard ranges. The simulation of the pool fire caused by the explosion is mainly to study the influence of various factors on the combustion characteristics and the extent of damage; and whether the conclusions from the small⁃scale oil pool test can be used for larger⁃scale pool fires needs further demonstration. The simulation model is corrected by the on⁃site big data of accident, and the simulation accuracy is improved, in order to provide theoretical support for the study of the explosive combustion characteristics and the enterprise prediction of the hazard range.
Bohai oilfield is rich in heavy oil resources. The strategy of water flooding and polymer flooding driven development in heavy oil blocks has been implemented for many years, and oil recovery has been greatly improved. Nevertheless, tubing corrosion, clingage accumulation and polymer scale stuck problems lead to injected volume and output quantity reduction, which have severely influenced the normal production and economic benefits. SZ 36⁃1A well located in Bohai oilfields and had carried out watering⁃polymer combined flooding for many years, which resulted in string corrosion and polymer scale stuck seriously. Meanwhile, the inside diameter of sand control pipe was so small that it could not carry out wash over operation. When it encounted bottleneck by adopting MPC cutting and back⁃off fishing technologies, the field engineers adopted decidedly the inner mechanical cutting, milling and back⁃off fishing. Finally, it salvaged all the fish and valuable experience was obtained as follow: a. in order to accumulate a large amount of polymer scale in the well, firstly apply a small oil pipe to thoroughly flush the well, and add a suitable descaling agent to the well washing liquid at the same time; b. as for tubing corrosion and scale⁃stucked wells, it should be treated by means of mechanical cutting dominated and milling assisted; c. during the milling period, it should maintain higher RPM and lower weight on bit, avoiding producing bigger metal debris and being alert of tool sticking. This paper systematically summarizes the salvage process, technical points and provides guiding suggestions for similar operations in Bohai oilfield in the future.
Friction stir welding (FSW) is an effective, environment⁃friendly solid state is an efficient and environmentally friendly solid phase bonding method, which has the characteristics of low temperature severe plastic deformation and high joint quality. FSW can effectively solve the problems associated with fusion welding in petroleum tanks and pipelines. However,due to the influence of welding parameters, working conditions and inherent mode of the method, friction stir welding has welding defects, which reduces the service life of the joint. The two major welding defects (global and local welding defects) were summarized in terms of characteristics and causes, while the repairing technologies for various defects were reviewed. This paper has practical significance for joint quality improvement, high⁃efficiency high⁃performance repairing and engineering applications.
