选取祁连山天然气水合物钻探区DK-8井岩心样品中的砂岩,利用模拟气合成含天然气水合物砂岩样品,并进行电阻率及介电常数研究。砂岩样品在天然气水合物形成后电阻率明显增大。在温度震荡过程中,电阻率测量能检测到水合物或冰的二次形成...选取祁连山天然气水合物钻探区DK-8井岩心样品中的砂岩,利用模拟气合成含天然气水合物砂岩样品,并进行电阻率及介电常数研究。砂岩样品在天然气水合物形成后电阻率明显增大。在温度震荡过程中,电阻率测量能检测到水合物或冰的二次形成。在天然气水合物形成过程中,体系的介电常数变化规律复杂,在1 k Hz^100 k Hz频段内,含水合物岩石的介电常数存在频散特性,频率高于100 k Hz,频散特性变弱。从介电常数的实验结果来看,基于介电常数的电法勘探技术可用来定性分析含水合物储层,但很难定量研究储层的水合物饱和度。展开更多
The experiments are carried out in the system of continuous flow reactors with dielectric-barrier discharge (DBD) for studies on the conversion of natural gas to C2 hydrocarbons through plasma catalysis under the atmo...The experiments are carried out in the system of continuous flow reactors with dielectric-barrier discharge (DBD) for studies on the conversion of natural gas to C2 hydrocarbons through plasma catalysis under the atmosphere pressure and room temperature. The influence of discharge frequency, structure of electrode, discharge voltage, number of electrode, ratio of H2/CH4, flow rate and catalyst on conversion of methane and selectivity of C2 hydrocarbons are investigated. At the same time, the reaction process is investigated. Higher conversion of methane and selectivity of C2 hydrocarbons are achieved and deposited carbons are eliminated by proper choice of parameters. The appropriate operation parameters in dielectric-barrier discharge plasma field are that the supply voltage is 20-40 kV (8.4-40 W), the frequency of power supply is 20 kHz, the structure of (b) electrode is suitable, and the flow of methane is 20-60 ml · min-1. The conversion of methane can reach 45%, the selectivity of C2 hydrocarbons is 76%, and the total selectivity of C2 hydrocarbons and C3 hydrocarbons is nearly 100%. The conversion of methane increases with the increase of voltage and decreases with the flow of methane increase; the selectivity of C2 hydrocarbons decreases with the increase of voltage and increases with the flow of methane increase. The selectivity of C2 hydrocarbons is improved with catalyst for conversion of natural gas to C2 hydrocarbons in plasma field. Methane molecule collision with radicals is mainly responsible for product formation.展开更多
Gas-insulated equipment(GIE)that utilizes the most potent greenhouse gas sulfur hexafluoride(SF_(6))as insulation and arc-quenching medium has been widely used in the power industry.Seeking eco-friendly insulating gas...Gas-insulated equipment(GIE)that utilizes the most potent greenhouse gas sulfur hexafluoride(SF_(6))as insulation and arc-quenching medium has been widely used in the power industry.Seeking eco-friendly insulating gas with advanced performance for next-generation SF_(6)-free GIE is significant for the“net-zero”goal and sustainable development.In this paper,the utilization,emission,and reduction policies of SF_(6)around the world were summarized first.Then,we systematically reviewed the latest progress in comprehensive performance evaluation of eco-friendly insulating gas in terms of molecular design,dielectric insulation,arc-quenching,stability and decomposition,materials compatibility,biosafety,etc.Further,the representative applications of eco-friendly insulating gas in medium-voltage,high-voltage GIE as well as relevant maintenance-related technologies were highlighted.Accordingly,the existing challenges and future perspectives were proposed,presenting a roadmap to hopefully steer the development of eco-friendly insulating gas and GIE.展开更多
An improved Monte Carlo method was used to simulate the motion of electrons in c-C4F8 and SF6 gas mixtures for pulsed townsend discharge. The electron swarm parameters such as effective ionization coefficient, -↑α a...An improved Monte Carlo method was used to simulate the motion of electrons in c-C4F8 and SF6 gas mixtures for pulsed townsend discharge. The electron swarm parameters such as effective ionization coefficient, -↑α and drift velocity over the E/N range from 280～700 Td（1Td=10^-21 V·m^2） were calculated by employing a set of cross sections available in literature. From the variation cure of -↑α with SF6 partial pressure p, the limiting field （E/N）lim of gas mixture at different gas content was determined. It is found that the limiting field of c-C4F8 and SF6 gas mixture is higher than that of pure SF6 at any SF6 mixture ratio. Simulation results show excellent agreement with experiment data available in previous literature.展开更多
Improving energy efficiency in plasma NO removal is a critical issue.When the surface dielectric barrier discharge(SDBD)device is considered as a combination of multiple plasma actuators,the induced plasma aerodynamic...Improving energy efficiency in plasma NO removal is a critical issue.When the surface dielectric barrier discharge(SDBD)device is considered as a combination of multiple plasma actuators,the induced plasma aerodynamic effect cannot be ignored,which can affect the mass transfer,then affect the chemical reactions.Five SDBD devices with different electrode arrangements are studied for NO conversion.They correspond to different flow patterns.We find that the energy efficiency in an SDBD device with a common structure(Type 1)is 28%lower than that in SDBD devices with a special arrangement(Types 2–5).Two reasons may explain the results.First,fewer active species are produced in Type 1 because the development of discharge is hindered by the mutually exclusive electric field forces caused by the symmetrically distributed charged particles.Second,the plasma wind induced by the plasma actuator can enhance the mass and heat transfer.The mixing of reactants and products is better in Types 2–5 than Type 1 due to higher turbulence kinetic energy.展开更多
文摘选取祁连山天然气水合物钻探区DK-8井岩心样品中的砂岩,利用模拟气合成含天然气水合物砂岩样品,并进行电阻率及介电常数研究。砂岩样品在天然气水合物形成后电阻率明显增大。在温度震荡过程中,电阻率测量能检测到水合物或冰的二次形成。在天然气水合物形成过程中,体系的介电常数变化规律复杂,在1 k Hz^100 k Hz频段内,含水合物岩石的介电常数存在频散特性,频率高于100 k Hz,频散特性变弱。从介电常数的实验结果来看,基于介电常数的电法勘探技术可用来定性分析含水合物储层,但很难定量研究储层的水合物饱和度。
基金This work was supported by the Science and Technology Development from the SINOPEC (Grant No. X500005) the National Natural Science Foundation of China (Grant No. 29776037).
文摘The experiments are carried out in the system of continuous flow reactors with dielectric-barrier discharge (DBD) for studies on the conversion of natural gas to C2 hydrocarbons through plasma catalysis under the atmosphere pressure and room temperature. The influence of discharge frequency, structure of electrode, discharge voltage, number of electrode, ratio of H2/CH4, flow rate and catalyst on conversion of methane and selectivity of C2 hydrocarbons are investigated. At the same time, the reaction process is investigated. Higher conversion of methane and selectivity of C2 hydrocarbons are achieved and deposited carbons are eliminated by proper choice of parameters. The appropriate operation parameters in dielectric-barrier discharge plasma field are that the supply voltage is 20-40 kV (8.4-40 W), the frequency of power supply is 20 kHz, the structure of (b) electrode is suitable, and the flow of methane is 20-60 ml · min-1. The conversion of methane can reach 45%, the selectivity of C2 hydrocarbons is 76%, and the total selectivity of C2 hydrocarbons and C3 hydrocarbons is nearly 100%. The conversion of methane increases with the increase of voltage and decreases with the flow of methane increase; the selectivity of C2 hydrocarbons decreases with the increase of voltage and increases with the flow of methane increase. The selectivity of C2 hydrocarbons is improved with catalyst for conversion of natural gas to C2 hydrocarbons in plasma field. Methane molecule collision with radicals is mainly responsible for product formation.
基金supported in part by the National Natural Science Foundation of China(Nos.52277144,52107145,and 51907023)the fellowship of China Postdoctoral Science Foundation(No.2022M712446).
文摘Gas-insulated equipment(GIE)that utilizes the most potent greenhouse gas sulfur hexafluoride(SF_(6))as insulation and arc-quenching medium has been widely used in the power industry.Seeking eco-friendly insulating gas with advanced performance for next-generation SF_(6)-free GIE is significant for the“net-zero”goal and sustainable development.In this paper,the utilization,emission,and reduction policies of SF_(6)around the world were summarized first.Then,we systematically reviewed the latest progress in comprehensive performance evaluation of eco-friendly insulating gas in terms of molecular design,dielectric insulation,arc-quenching,stability and decomposition,materials compatibility,biosafety,etc.Further,the representative applications of eco-friendly insulating gas in medium-voltage,high-voltage GIE as well as relevant maintenance-related technologies were highlighted.Accordingly,the existing challenges and future perspectives were proposed,presenting a roadmap to hopefully steer the development of eco-friendly insulating gas and GIE.
文摘An improved Monte Carlo method was used to simulate the motion of electrons in c-C4F8 and SF6 gas mixtures for pulsed townsend discharge. The electron swarm parameters such as effective ionization coefficient, -↑α and drift velocity over the E/N range from 280～700 Td（1Td=10^-21 V·m^2） were calculated by employing a set of cross sections available in literature. From the variation cure of -↑α with SF6 partial pressure p, the limiting field （E/N）lim of gas mixture at different gas content was determined. It is found that the limiting field of c-C4F8 and SF6 gas mixture is higher than that of pure SF6 at any SF6 mixture ratio. Simulation results show excellent agreement with experiment data available in previous literature.
基金supported by the National Natural Science Foundation of China(60906053,61204069,61274118,61306144,61504079,and 11605112)Scientific and Innovative Action Plan of Shanghai(15DZ1160800 and 17XD1702400)China Postdoctoral Science Foundation(2016 M601595).
文摘Improving energy efficiency in plasma NO removal is a critical issue.When the surface dielectric barrier discharge(SDBD)device is considered as a combination of multiple plasma actuators,the induced plasma aerodynamic effect cannot be ignored,which can affect the mass transfer,then affect the chemical reactions.Five SDBD devices with different electrode arrangements are studied for NO conversion.They correspond to different flow patterns.We find that the energy efficiency in an SDBD device with a common structure(Type 1)is 28%lower than that in SDBD devices with a special arrangement(Types 2–5).Two reasons may explain the results.First,fewer active species are produced in Type 1 because the development of discharge is hindered by the mutually exclusive electric field forces caused by the symmetrically distributed charged particles.Second,the plasma wind induced by the plasma actuator can enhance the mass and heat transfer.The mixing of reactants and products is better in Types 2–5 than Type 1 due to higher turbulence kinetic energy.
