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Catalytic combustion properties of nanocomplex oxide for natural gas
The catalysts of copper oxide supported on cerium dioxide were prepared by different methods for methane catalytic combustion. The effects of copper content in the catalysts and calcination temperatures of the catalysts on the catalytic activity are investigated. Results show that the complex oxide catalyst exhibits high catalytic activity for methane combustion due to the synergistic effect of CuO and CeO2. The catalyst prepared by impregnation is more active than that prepared by controlled coprecipitation even if CuO content is the same. When W(CuO) ＜13%, the light-off temperature and full conversion temperature for the CH4 reaction decrease with the increasing of CuO content in the catalysts. However, when the copper content is above 13%, the excess CuO has a negative effect on the catalytic activity owing to the formation of bulk CuO particles. A proper calcinations temperature of 650 ℃ can lead to a high dispersion of CuO and accordingly can enhance the catalytic activity of the composites....
2020-09-13 23:35:02浏览：62
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Fracture development in shale and its relationship to gas accumulation
Shale with high quartz,feldspar and carbonate,will have low Poisson's ratio,high Young's modulus and high brittleness.As a result,the shale is conducive to produce natural and induced fractures under external forces.In general,there is a good correlation between fracture development in shale and the volume of brittle minerals present.Shale with high TOC or abnormally high pressure has well-developed fractures.Shale fracture development also shows a positive correlation with total gas accumulation and free gas volume,i.e.,the better shale fractures are developed,the greater the gas accumulation and therefore the higher the gas production.Fractures provide migration conduits and accumulation spaces for natural gas and formation water,which are favorable for the volumetric increase of free natural gas.Wider fractures in shale result in gas loss.In North America,there is a high success ratio of shale gas exploration and high gas production from high-angle fracture zones in shale.Good natural gas shows or low yield producers in the Lower Paleozoic marine organic matter-rich rocks in the Sichuan Basin are closely related to the degree of fracture development in brittle shales....
2020-09-13 23:35:02浏览：35
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EFFECTS OF GAS TYPE AND TEMPERATURE ON FINE PARTICLE FLUIDIZATION
The influence of gas type (helium and argon) and bed temperature (77-473 K) on the fluidization behaviour of Geldart groups C and A particles was investigated. For both types of particles tested, i.e., Al2O3 (4.8 μm) and glass beads (39 μm), the fluidization quality in different gases shows the following priority sequence: Ar＞He. In the same gaseous atmosphere, the particles when fluidized at an elevated temperature usually show larger bed voidages, higher bed pressure drops, and a lower umf for the group A powder, all indicating an enhancement in fluidization quality. Possible mechanisms governing the operations of gas type and temperature in influencing the fluidization behaviours of fine particles have been discussed with respect to the changes in both gas properties and interparticle forces (on the basis of the London-van der Waals theory). Gas viscosity (varying significantly with gas-type and temperature) proves to be the key parameter that influences the bed pressure drops and umf in fluidization of fine particles, while the interparticle forces (also varying with gas-type and temperature) may play an important role in fine-particle fluidization by affecting the expansion behaviour of the particle-bed....
2020-09-13 23:35:02浏览：32
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Advances in the Partial Oxidation of Methane to Synthesis Gas
The conversion and utilization of natural gas is of significant meaning to the national economy,even to the everyday life of people. However, it has not become a popular industrial process as expected due to the technical obstacles. In the past decades, much investigation into the conversion of methane,predominant component of natural gas, has been carried out. Among the possible routes of methane conversion, the partial oxidation of methane to synthesis gas is considered as an effective and economically feasible one. In this article, a brief review of recent studies on the mechanism of the partial oxidation of methane to synthesis gas together with catalyst development is wherein presented....
2020-09-13 23:35:02浏览：91
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Electricity Pricing for Natural Gas CHP Projects
Regarding the state's policy that gtves a higher on-grid electricity price to natural gas CHP (combined heat and power) projects,this paper studies the effect of it on the operation of those projects by theoretical analysis and a case study,It concludes thar on-grid electricity price on the high side,compared to heat price,will lead power plants to produce more electricity but less heat,thus catusing decrease of the plants ' thermal efficiency and harm to energy saving of the whole society....
2020-09-13 23:35:02浏览：49
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Indirect Indicators of Gas HydrateOccurrence within Submarine Sediments
Gas hydrate, a new kind energy resources discoverd over the past ten years, has aroused much attention from many countries around the globe, because the gas hydrate has played a very important role in energy resources exploration, submarine geohazards precaution, and changes in global climate. So far, gas hydrates have been found in about sixty places on continental margins and polar regions in the world, but the majority of them is recognized by all kinds of indirect indicators owing to their limited existence conditions, only minority of them is collected. Thereby, the indirect marks of gas hydrates play an important role in exploration of the clathrate compounds, and the authors discuss them....
2020-09-13 23:35:02浏览：46
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Kinetic model on coke oven gas with steam reforming
The effects of factors such as the molar ratio of H2O to CH4 (n(H2O)/n(CH4)), methane conversion temperature and time on methane conversion rate were investigated to build kinetic model for reforming of coke-oven gas with steam. The results of experiments show that the optimal conditions for methane conversion are that the molar ratio of H2O to CH4 varies from 1.1 to 1.3and the conversion temperature varies from 1 223 to 1 273 K. The methane conversion rate is more than 95% when the molar ratio ofH2O to CH4 is 1.2, the conversion temperature is above 1 223 K and the conversion time is longer than 0.75 s. Kinetic model of methane conversion was proposed. All results demonstrate that the calculated values by the kinetic model accord with the experimental data well, and the error is less than 1.5%....
2020-09-13 23:35:02浏览：32
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Research on the explosion characteristics of chlorine dioxide gas
The explosion characteristics of chlorine dioxide gas have been studied for the first time in a cylindrical exploder with a shell capacity of 201.The experimental results have indicated that the lower concentration limit for the explosive decomposition of chlorine dioxide gas is 9.5% ([ClO2]/[airl),whereas there is no corresponding upper concentration limit.The maximum pressure of explosion relative to the initial pressure was measured as 0.024 MPa at 10% ClO2 and 0.641 MPa at 90% ClO2.The induction time (the time from the moment of sparking to explosion) at 10% ClO2 was 2195 ms,but at 90% ClO2 the induction time was just 8 ms.The explosion reaction mechanism of ClO2 is of a degenerate chain-branching type involving the formation of a stable intermediate (Cl2O3),from which the chain branching occurs....
2020-09-13 23:35:02浏览：70
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Calculation analysis of sustained casing pressure in gas wells
Sustained casing pressure (SCP) in gas wells brings a serious threat to worker safety and environmental protection.According to geological conditions,wellbore structure and cement data of gas wells in the Sichuan-Chongqing region,China,the position,time,environmental condition and the value of SCP have been analyzed.On this basis,the shape of the pressure bleed-down plot and pressure buildup plot were diagnosed and the mechanism of SCP has been clarified.Based on generalized annular Darcy percolation theory and gas-liquid two-phase fluid dynamics theory,a coupled mathematical model of gas migration in a cemented annulus with a mud column above the cement has been developed.The volume of gas migrated in the annulus and the value of SCP changing with time in a gas well in Sichuan have been calculated by this model.Calculation results coincided well with the actual field data,which provide some reference for the following security evaluation and solution measures of SCE...
2020-09-13 23:35:02浏览：48
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Experiments on Gas Jet in the Wendelstein 7-AS Stellarator
Wendelstein 7-AS (W7-AS) pertains to an advanced helical stellarator. A new fu-elling method, the supersonic molecular beam injection (SMBI, named Gas Jet in Germany)system was installed in W7-AS in May 2001 as a cooperation research item co-supported by theNational Nature Science Foundation of China and the Max-Planck Institute of Plasma Physics,Garching, Germany. The experiments of the gas jet with hydrogen or deuterium on W7-AS wereimplemented. The experimental results exhibit the following features such as high fuelling ef-ficiency, stable high-density plasmas and reduction of the recycling fluxes from the vessel wallduring injection. These crucial points show that the new fuelling method can be applied to longand stable discharges....
2020-09-13 23:35:02浏览：70
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Gas-sensing properties of nanocomplex metal oxide
The development of CuO/CeO2 nanocomposites as the sensing material of semiconductor gas sensors is reported.CuO/CeO2 nanocomplex oxide is prepared by modified sol-gel method that uses copper nitrate, cerium nitrate and ethylene glycol as precursors. The optimized synthesis parameters and processing condition have been established. The particle size and distribution, phase morphology, specific surface, electronic states of atoms and gas sensing properties have been systematically characterized by Transmission Electron Microscope (TEM), Brunauer Emmett Teller (BET), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and gas sensitivity measurement. The results show that the sensor sensitivity depends on particle size, Cu/Ce cation ratio and calcination temperature. The effects of calcinations temperature and CuO loading on the gas sensitivity are also examined. The optimum calcination temperature and the CuO content for the highest sensitivity are 600 ℃ and 12%, respectively. The combination of excellent thermal stability.and tunable sensing properties through careful control of the processing parameters and selection of material composition gives rise to novel nanocomposites attractive to the sensitive and selective detection of a variety of toxic and combustible gases....
2020-09-13 23:35:02浏览：40
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STUDY FOR NATURAL GAS HYDRATE CONVERSED FROM ICE
Natural gas hydrates are crystalline clathrate compounds composed of water and gases of small molecular diameters that can be used for storage and transport of natural gas as a novel method. In the paper a series of experiments of aspects and kinetics for hydrate formed from natural gas and ice were carried out on the industrial small scale production apparatus. The experimental results show that formation conditions of hydrate conversed from ice are independent of induction time, and bigger degrees of supersaturation and supercooling improved the driving force and advanced the hydrate formation.Superpressure is also favorable for ice particle conversion to hydrate. In addition, it was found there have an optimal reaction time during hydrate formation....
2020-09-13 23:35:02浏览：61
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Friction resistance for gas flow in smooth microtubes
A new tube-cutting method was used to measure the pressure and Mach number distribution along a microtube of 108.3 μm. Experiments were also performed concerning the average Fanning friction factors of five kinds of microtubes whose diameters range from 80.0 to 166.6 μm. It is found that the pressure distribution in a microtube becomes nonlinear at a high Mach number and the product of measured average Fanning friction factors Cf and Reynolds number Re is higher than 16. Numerical results show that the gas compressibility leads to a variation of the velocity profile from parabolic, and results in a large velocity gradient at the tube inner wall surface. The transition from laminar to turbulence in microtubes also occurs at Re≈2 300, and the phenomenon of early transition is not observed in the experiments....
2020-09-13 23:35:02浏览：34
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The Gas Resources Assessment Expert System of the Songliao Basin
The gas resources assessment expert system is one of the advanced methods for appraising oil and gas resources. The establishment of a knowledge base is the focal task in developing the expert system. This paper presents a summary of the mechanism and the major controlling factors in the formation of gas pools in the southeast uplift of the Songliao basin. Then an appropriate assessment model is established for trapping the gas resources and a knowledge base built in the expert system to realize the model. By using the expert system to appraise the gas-bearing probability of 25 major traps of the Quantou and Denglouku Formations in the Shiwu-Dehui area, the authors have proved that the expert system is suitable for appraising traps in the Songliao basin and similar basins....
2020-09-13 23:35:02浏览：51
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Affecting Factors and Improving Measures for Converter Gas Recovery
To change the undesirable present situation of recovering and using converter gas in steel plants in China,the basic approaches to improving the converter gas recovery rate were analyzed theoretically along with the change curves of the converter gas component content, based on the converter gas recovery system of Baosteel No. 2 steelmaking plant. The effects of converter device, raw material, air imbibed quantity, recovery restricted condition, and intensity of oxygen blowing on the converter gas recovery rate were studied. Among these, the effects of the air imbibed quantity, recovery restricted condition, and intensity of oxygen blowing are remarkable. Comprehensive measures were put forward for improving the converter gas recovery from the point of devices, etc. , and good results were achieved....
2020-09-13 23:35:02浏览：70
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