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Numerical simulation of detonation of an explosive atmosphere of liquefied petroleum gas in a confin
The detonation of an explosive atmosphere from liquefied petroleum gas disseminated in air in a confined space is studied using numerical modeling with software product ANSYS AUTODYN....
2020-09-15 12:28:59浏览：70
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Impact of Improving Design Factor over 0.72 on the Safety and Reliability of Gas Pipelines and Feasi
Many years experience of the operation of high stress (＞72％ specified minimum yield strength,SMYS) gas pipelines and statistical analysis results of pipeline incidents showed that the operating pipelines at stress levels over 72％ SMYS have not presented problems in USA and Canada,and design factor does not control incidents or the safety of pipelines.Enhancing pipeline safety management level is most important for decreasing incident rate.The application history of higher design factors in the U.S and Canada was reviewed.And the effect of higher factors to the critical flaw size,puncture resistance,change of reliability with time,risk level and the arrest toughness requirements of pipeline were analyzed hem.The comparison of pipeline failure rates and risk levels between two design factors (0.72 and 0.8) has shown that a change in design factor from 0.72 to 0.8 would bring little effect on failure rates and risk levels.On the basis of the analysis result,the application feasibility of design factor of 0.8 in China was discussed and the related suggestions were proposed.When an operator wishes to apply design factor 0.8 to gas pipeline,the following process is recommended:stress level of line pipe hydro test should be up to 100％ SMYS,reliability and risk assessment at the design feasibility or conceptual stage should be conducted,Charpy impact energy should meet the need of pipeline crack arrest; and establish and execute risk based integrity management plan.The technology of pipeline steel metallurgy,line pipe fabrication and pipeline construction,and line pipe quality control level in China achieved tremendous progresses,and line pipe product standards and property indexes have come up to international advanced level.Furthermore,pipeline safety management has improved greatly in China.Consequently,the research for the feasibility of application of design factor of 0.8 in China has fundamental basis....
2020-09-15 12:28:59浏览：63
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Study on Pressure Swing Adsorption Removing C+2 from Natural Gas as Raw Material for Thermal Chlorin
The experimental investigation demonstrates that a satisfactory result can be expected for pressure swing adsorption (PSA) purification of natural gas as raw material for thermal chlorination process. Using hh-4 molecular sieve as adsorbent for removing C2+ components, the suitable adsorption pressure is 0.4-0.45 MPa, desorption vacuum is 0.08-0.09 MPa and circulation time is 20-21 min....
2020-09-15 12:28:59浏览：52
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Synthesis of Dimethyl Ether from CO Hydrogenation: a Thermodynamic Analysis of the Influence of Wate
Three reactions involved in dimethyl ether (DME) synthesis from CO hydrogenation: methanol synthesis reaction (MSR), methanol dehydration reaction (MDR) and water gas shift reaction (WGSR) are studied by thermodynamic calculation. For demonstrating this process in detail, three models, MSR,MSR+MDR, MSR+MDR+WGSR, are used. Their basic characteristics can be obtained by varying widely the ratios of H2 to CO in the feed (no CO2). Through thermodynamic analysis a chemical synergic effect obviously exists in the second and third models. By comparison between two models it is found that WGSR plays a special role in dimethyl ether synthesis. It is possible for the two models to shift one to the other by regulating CO2 concentration in feed. For Model 2, the selectivity for DME in oxygenates (DME+methanol) does not change with the ratio of H2 to CO....
2020-09-15 12:28:59浏览：42
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Characterization of 17-4PH stainless steel powders produced by supersonic gas atomization
17-4PH stainless steel powders were prepared using a supersonic nozzle in a close-coupled gas atomization system.The characteristics of powder particles were carried out by means of a laser particle size analyzer,scanning electron microscopy (SEM),and the X-ray diffraction (XRD) technique.The results show that the mass median particle diameter is about 19.15 μm.Three main types of surface microstructures are observed in the powders:well-developed dendrite,cellular,and cellular dendrite structure.The XRD measurements show that,as the particle size decreases,the amount of fcc phase gradually decreases and that of bcc phase increases.The cooling rate is inversely related to the particle size,i.e.,it decreases with an increase in particle size....
2020-09-15 12:28:59浏览：40
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Partial Oxidation of Methane to Synthesis Gas over Hexaaluminates LaMAl11O19-δ catalysts
A series of M-substituted hexaaluminates LaMAl11O19-δ (M=Fe, Co, Ni, Mn, and Cu)were prepared and characterized by XRD, XPS, TPR and TGA techniques, respectively. They exhibited different reducibility and catalytic activity for partial oxidation of methane (POM) to synthesis gas. Among the LaMAl11O19-δ samples, LaNiAl11O19-δ showed the best catalytic activity for the topic reaction and selectivity for synthesis gas at 780 ℃ for 2 h. The conversion of CH4 was over 99.2%, and the product selectivity for both CO and H2 was above 90.3%....
2020-09-15 12:28:59浏览：57
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Study of 3-D Numerical Simulation for Gas Transfer in the Goaf of the Coal Mining
In order to simulate field distribution rules, mathematical models for 3-D air flows and gas transfer in the goaf of the coal mining are established, based on theories of permeability and dynamic dispersion through porous media. A gas dispersion equation in a 3-D field is calculated by use of numerical method on a weighted upstream multi-element balance. Based on data of an example with a U type ventilation mode, surface charts of air pressure distribution and gas concentration are drawn by Graphtool software. Finally, a comparison between actually measured results in the model test and the numerical simulation results is made to proves the numerical implementation feasible....
2020-09-15 12:28:59浏览：44
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CALCULATION OF COUPLED PROBLEM BETWEEN TEMPERATURE AND PHASE TRANSFORMATION DURING GAS QUENCHING IN
The gas quenching is a modern, effective processing technology. On the basis of nonlinear surface heat-transfer coefficient obtained by Cheng during the gas quenching,the coupled problem between temperature and phase transformation during gas quenching in high pressure was simulated by means of finite element method. In the numerical calculation, the thermal physical properties were treated as the functions of temperature and the volume fraction of phase constituents. In order to avoid effectual "oscillation"of the numerical solutions under smaller time step, the Norsette rational approximate method was used....
2020-09-15 12:28:59浏览：57
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Influence of gas flow on thermal field and stress during growth of sapphire single crystal using Kyr
The professional modeling software package CrysVUn was employed to study the process of a large sapphire single crystal growth using Kyropoulos method.The influence of gas pressure on thermal field, solid-liquid interface shape, gas velocity field and von Mises stress were studied for the first time.It is found that the root of the seed melt when gas pressure equals to one atmosphere or more than one atmosphere, especially during the seeding period, this result is consistent with the experimental observation, and this paper presents three ways to solve this problem.The temperature gradient and stress decreases significantly as the gas pressure increases.The convexity of the solid-liquid interface slightly increases when the gas pressure increases.Numerical analysis was used to optimize the hot zone design....
2020-09-15 12:28:59浏览：63
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Determination of constituents of essential oil from Angelica sinensis by gas chromatography-mass spe
Gas chromatography-mass spectrometry (GC-MS) coupled with chemometric resolution upon two-dimensional data was employed to analyze the constituents of essential oils of Angelica sinensis. Constituents in essential oils of Angelica sinensis root were identified by GC-MS with the help of subwindow factor analysis (SFA) method resolving two-dimensional original data into mass spectra and chromatograms. 76 of 97 separated constituents in essential oil of Angelica sinensis root were identified and quantified, and they account for about 91.36% of the total content. The results show that ligustilide, butylene phthalide, 2-methoxy-4-vinylphenol, carvacrol, allo-ocimene,2,6,6-trimethylbicyclo-[3,1,1]hept-2-ene are the main constituents in essential oil of Angelica sinensis root....
2020-09-15 12:28:59浏览：65
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Filter paper-templated preparation of ZnO thin films and examination of their gas-sensing properties
ZnO thin films prepared by using quantitative filter paper as a template and Zn(CHsCO2)2·2H2O ethanol precursor solution were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of sample calcination temperature, precursor concentration and filter paper types were studied, and the growth process was investigated by infra-red (IR) spectroscopy and thermogravimettic analysis/differential thermal analysis (TGA/DTA). The results show that samples soaked in a 1.5 mol/L Zn( CH3 CO2 )2.2 H2O ethanol solution and calcined at 600 ℃ yield ZnO films of uniform particle size, approximately 30, 40 and 50 nm, for fast-, medium- and slow-speed filter papers, respectively. The formaldehyde gas sensing properties of the ZnO nanoparticles were tested, showing that the material prepared from fast-speed filter paper has a higher response to 120-205 ppm formaldehyde at 400 ℃ than that prepared from medium- or slow-speed paper, which depends on the particle size....
2020-09-15 12:28:59浏览：59
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Gas hydrate fast nucleation from melting ice and quiescent growth along vertical heat transfer tube
During the observation of HCFC141b gas hydrate growth processes outside a vertical heat transfer tube, two exciting phenomena were found: fast nucleation of gas hydrate from melting ice, and the spontaneous permeation of water into the guest phases along the surface of heat transfer tube to form gas hydrate continuously. These two phenomena were explained with Zhou & Sloan's hypothesis and the theory of surface free energy respectively, and a novel method of gas hydrate formation was presented--gas hydrate fast nucleation from melting ice and quiescent growth along heat transfer tube. There is no mechanic stirring in this method, the formed gas hydrates are compact, the ratio of unreacted interstitial water is little, which overcome the drawback of high energy cost and high ratio of unreacted interstitial water among the formed gas hydrates in the system with mechanic stirring. This finding will benefit the gas hydrate application technologies such as natural gas storage technology or cool storage technology with gas hydrate....
2020-09-15 12:28:59浏览：70
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Geochemistry and genesis on saturated hydrocarbon of crude oils in Gas Hure Oilfield in Qaidam Basin
Gas Hure Oilfield is the biggest one in the Qaidam Basin.Through intensive sampling and GC-MS analysis, the authors analyzed the geochemical characteristics of the crude oils in the Gas Hure Oilfield.The results show that the crude oils have even-odd carbon predominance for n-alkanes.In shallow reservoir, part of crude oils suffered biogenic degradation.As for normal oils, they have low Pr/Ph ratios with abundant gammacerane and C35 homohopane, which indicate that the crude oils are formed in strong reducing salt water environment.Compared deep ( E13 ) reservoir with shallow ( N1 - N12 ) reservoir, the ancient salinity of sedimentary environment of N1-N12 crude oils is slightly higher than that of E13 crude oils; the C-21/C+22 ratios of crude oils are 1.02-1.71 with a higher abundance of C27sterane, which shows that their mainly origin matrix are bacteria and algae; the C29 sterane 20S/(20S + 20R)is generally low, the ratio in deep E13 reservoir distributes between 0.31and 0.40, but in shallow reservoir is relatively low with O.29-0.36.At the same time, C29sterane αββ/( αββ + ααα) and Ts/Tm both are extremely lower.All the above show that the crude oils in Gas Hure are mainly low mature oils, although the maturity of deep reservoir crude oils is slightly higher than shallow one....
2020-09-15 12:28:59浏览：59
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Geochemical characteristics and possible origin of natural gas in the Taibei Depression, Turpan-Hami
292 chemical composition data and 82 isotopic composition data of gas samples collected from the Taibei Depression of the Turpan-Hami Basin, West China, were used in the study of their origin. Non-hydrocarbon gas is poor in most samples whereas abundant nitrogen in some samples is positively correlated with δ13C1. Although methane is the main constituent, higher molecular gaseous hydrocarbons, from ethane to pentane, are detected in most samples, in accordance with the distribution of oil reservoirs. The stable carbon isotope ratios of methane, eth-ane and propane are defined as d13C1: -45.5‰ to -33.5‰, d13C2: -30.2‰ to -10.5‰, and d13C3: 27.6‰ to -11.2‰, respectively. According to the distribution of carbon isotope ratios, 2 families of gas can be grouped, most showing normal distribution of carbon isotopes, and others having obvious heavier carbon isotopes and being of abnormal distribution. Based on the isotopic composition, the disagreement between the relationship of Δ(d13C1-d13C2) and d13C2 and that of Δ(d13C1-d13C2) and d13C2, and the calculated Ro, there are oil-associated gas, coal-derived gas and mixture of them. Other samples with obviously heavier isotopic compositions from the Yanmuxi oilfield of the Taibei Depression have been degraded by organisms....
2020-09-15 12:28:59浏览：55
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Examining the Gas Sensing Properties of the Nanocrystalline Sm2O3-WO3
In this study, nanocrystalline (NC) WO3 and Sm2O3-WO3 gas sensors have been synthesized and deposited on Al2O3 substrate by gas condensation method, then sintering to 600℃. SEM is used to observe the morphology of the surface. TEM is used to measure the particle size. The resistance of sensor is measured in different temperatures and gas concentration to evaluate the sensing properties of NC WO3 and NC Sm2O3-WO3 sensor. The results indicate that WO3 is a usability gas sensor material. After Sm2O3 is doped in WO3, it does not obviously influence CO detection; it owns better sensitivity and stability. To UV irradiation on WO3, the sensitivity of WO3 is enhanced and it maintains WO3 recovery properties in NO2 detecting. UV irradiation on Sm2O3 doped WO3 does not show enhanced well properties as UV illuminate on WO3....
2020-09-15 12:28:59浏览：58
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