As longwall caving mining method prevails rapidly in China coal mines, amount of gas emission from longwall faces and goaf area increased significantly. Using traditional gas drainage methods, such as drilling upward ...As longwall caving mining method prevails rapidly in China coal mines, amount of gas emission from longwall faces and goaf area increased significantly. Using traditional gas drainage methods, such as drilling upward holes to roof strata in tailgate or drilling inseam and cross-measure boreholes, could not meet methane drainage requirements in a gassy mine. The alternative is to drill boreholes from surface down to the Iongwall goaf area to drain the gas out. As soon as a coal seam is extracted out, the upper rock strata above the goaf start to collapse or become fractured depending upon the rock characteristics and the height above the coal seam. During overlying rock strata being fractured, boreholes in the area may be damaged due to ground movement after the passage of the Iongwall face. The sudden damage of a borehole may cause a Iongwall production halt or even a serious mine accident. A theoretical calculation of the stability of surface boreholes in mining affected area is introduced along with an example of determination of borehole and casing diameters is given for demonstration. By using this method for the drilling design, the damage of surface boreholes caused by excessive mining induced displacement can be effectively reduced if not totally avoided. Borehole and casing diameters as well as characteristics of filling materials can be determined using the proposed method by calculating the horizontal movement and vertical stain at different borehole depths.展开更多
Utilizing energy storage in depleted oil and gas reservoirs can improve productivity while reducing power costs and is one of the best ways to achieve synergistic development of"Carbon Peak–Carbon Neutral"a...Utilizing energy storage in depleted oil and gas reservoirs can improve productivity while reducing power costs and is one of the best ways to achieve synergistic development of"Carbon Peak–Carbon Neutral"and"Underground Resource Utiliza-tion".Starting from the development of Compressed Air Energy Storage(CAES)technology,the site selection of CAES in depleted gas and oil reservoirs,the evolution mechanism of reservoir dynamic sealing,and the high-flow CAES and injection technology are summarized.It focuses on analyzing the characteristics,key equipment,reservoir construction,application scenarios and cost analysis of CAES projects,and sorting out the technical key points and existing difficulties.The devel-opment trend of CAES technology is proposed,and the future development path is scrutinized to provide reference for the research of CAES projects in depleted oil and gas reservoirs.展开更多
Causality Diagram (CD) is a new graphical knowledge representation based on probability theory. The application of this methodology in the safety analysis of the gas explosion in collieries was discussed in this paper...Causality Diagram (CD) is a new graphical knowledge representation based on probability theory. The application of this methodology in the safety analysis of the gas explosion in collieries was discussed in this paper, and the Minimal Cut Set, the Minimal Path Set and the Importance were introduced to develop the methodology. These concepts are employed to analyze the influence each event has on the top event ? the gas explosion, so as to find out about the defects of the system and accordingly help to work out the emphasis of the precautionary work and some preventive measures as well. The results of the safety analysis are in accordance with the practical requirements; therefore the preventive measures are certain to work effectively. In brief, according to the research CD is so effective in the safety analysis and the safety assessment that it can be a qualitative and quantitative method to predict the accident as well as offer some effective measures for the investigation, the prevention and the control of the accident.展开更多
This paper performs an experimental evaluation of thermolysis-driven gases generated by the thermal decomposition of 1 M LiPF6+EC/DMC=1/1 v/v electrolytes at various decomposition temperatures,pyrolysis durations,and ...This paper performs an experimental evaluation of thermolysis-driven gases generated by the thermal decomposition of 1 M LiPF6+EC/DMC=1/1 v/v electrolytes at various decomposition temperatures,pyrolysis durations,and oxygen concentrations.Carried out in a home-built autoclave filled with pure helium,the experiment reveals that as the decomposition temperature increases,more types and larger quantities of gases will be released.Specifically,the experimental results demonstrate trends of logistic growth in the volume concentration of CO2,C2H6O,C2H4,CO,and C2H4O2 with the increase of decomposition temperature.With a prolonged pyrolysis duration,while volume concentrations of certain gases,such as CO2,C2H6O,C2H5F,and CO would increase,the concentration of C2H4O2 actually decreases.Moreover,concentrations of both C2H4 and C2H5F will first decrease and reach their minimum values at 1%v/v oxygen concentration,and then they would quickly climb back at higher oxygen concentrations,while the concentrations of C2H6 and C2H3F would decrease monotonically.It is envisioned that the detailed experimental results and findings on the gas generation pattern of 1 M LiPF6+EC/DMC=1/1 v/v electrolytes can facilitate the development of an early warning mechanism of thermal runaway based on gas sensing technology,which can be effectively applied to monitor the potential thermal failures of lithium-ion batteries with the same type of electrolyte and thus promote the thermal safety of battery packs in safety-critical applications.展开更多
With the widespread application of liquefied petroleum gas (LPG),the safety of LPG cylinder has received more and more attention.For the safety of LPG cylinder,we conduct a safety risk assessment of cylinder using the...With the widespread application of liquefied petroleum gas (LPG),the safety of LPG cylinder has received more and more attention.For the safety of LPG cylinder,we conduct a safety risk assessment of cylinder using the failure mode and effect analysis (FMEA) method.Taking the most influential inflatable fatigue under normal conditions as the research object,we use FE-safe software to analyze the fatigue failure.The risk compliance coefficients of various failure modes are calculated and classified according to the risk level.In this way,the service life of the LPG cylinder weld is determined.The presented method improves the safety risk assessment process of LPG cylinder and provides a good theoretical and practical basis for similar pressure vessel risk assessment.展开更多
文摘As longwall caving mining method prevails rapidly in China coal mines, amount of gas emission from longwall faces and goaf area increased significantly. Using traditional gas drainage methods, such as drilling upward holes to roof strata in tailgate or drilling inseam and cross-measure boreholes, could not meet methane drainage requirements in a gassy mine. The alternative is to drill boreholes from surface down to the Iongwall goaf area to drain the gas out. As soon as a coal seam is extracted out, the upper rock strata above the goaf start to collapse or become fractured depending upon the rock characteristics and the height above the coal seam. During overlying rock strata being fractured, boreholes in the area may be damaged due to ground movement after the passage of the Iongwall face. The sudden damage of a borehole may cause a Iongwall production halt or even a serious mine accident. A theoretical calculation of the stability of surface boreholes in mining affected area is introduced along with an example of determination of borehole and casing diameters is given for demonstration. By using this method for the drilling design, the damage of surface boreholes caused by excessive mining induced displacement can be effectively reduced if not totally avoided. Borehole and casing diameters as well as characteristics of filling materials can be determined using the proposed method by calculating the horizontal movement and vertical stain at different borehole depths.
基金the financial support from the Scientific Research and Technology Development Project of China Energy Engineering Corporation Limited(CEEC-KJZX-04).
文摘Utilizing energy storage in depleted oil and gas reservoirs can improve productivity while reducing power costs and is one of the best ways to achieve synergistic development of"Carbon Peak–Carbon Neutral"and"Underground Resource Utiliza-tion".Starting from the development of Compressed Air Energy Storage(CAES)technology,the site selection of CAES in depleted gas and oil reservoirs,the evolution mechanism of reservoir dynamic sealing,and the high-flow CAES and injection technology are summarized.It focuses on analyzing the characteristics,key equipment,reservoir construction,application scenarios and cost analysis of CAES projects,and sorting out the technical key points and existing difficulties.The devel-opment trend of CAES technology is proposed,and the future development path is scrutinized to provide reference for the research of CAES projects in depleted oil and gas reservoirs.
基金Supported by the Natural Science Foundation of China (No. 59677009) the National Research Foundation for the Doctoral Program of Higher Education of China (No.99061116)
文摘Causality Diagram (CD) is a new graphical knowledge representation based on probability theory. The application of this methodology in the safety analysis of the gas explosion in collieries was discussed in this paper, and the Minimal Cut Set, the Minimal Path Set and the Importance were introduced to develop the methodology. These concepts are employed to analyze the influence each event has on the top event ? the gas explosion, so as to find out about the defects of the system and accordingly help to work out the emphasis of the precautionary work and some preventive measures as well. The results of the safety analysis are in accordance with the practical requirements; therefore the preventive measures are certain to work effectively. In brief, according to the research CD is so effective in the safety analysis and the safety assessment that it can be a qualitative and quantitative method to predict the accident as well as offer some effective measures for the investigation, the prevention and the control of the accident.
基金supported by the National Natural Science Foundation of China(51877203)the Science and Technology Foundation of State Grid Corporation of China(521205190014).
文摘This paper performs an experimental evaluation of thermolysis-driven gases generated by the thermal decomposition of 1 M LiPF6+EC/DMC=1/1 v/v electrolytes at various decomposition temperatures,pyrolysis durations,and oxygen concentrations.Carried out in a home-built autoclave filled with pure helium,the experiment reveals that as the decomposition temperature increases,more types and larger quantities of gases will be released.Specifically,the experimental results demonstrate trends of logistic growth in the volume concentration of CO2,C2H6O,C2H4,CO,and C2H4O2 with the increase of decomposition temperature.With a prolonged pyrolysis duration,while volume concentrations of certain gases,such as CO2,C2H6O,C2H5F,and CO would increase,the concentration of C2H4O2 actually decreases.Moreover,concentrations of both C2H4 and C2H5F will first decrease and reach their minimum values at 1%v/v oxygen concentration,and then they would quickly climb back at higher oxygen concentrations,while the concentrations of C2H6 and C2H3F would decrease monotonically.It is envisioned that the detailed experimental results and findings on the gas generation pattern of 1 M LiPF6+EC/DMC=1/1 v/v electrolytes can facilitate the development of an early warning mechanism of thermal runaway based on gas sensing technology,which can be effectively applied to monitor the potential thermal failures of lithium-ion batteries with the same type of electrolyte and thus promote the thermal safety of battery packs in safety-critical applications.
文摘With the widespread application of liquefied petroleum gas (LPG),the safety of LPG cylinder has received more and more attention.For the safety of LPG cylinder,we conduct a safety risk assessment of cylinder using the failure mode and effect analysis (FMEA) method.Taking the most influential inflatable fatigue under normal conditions as the research object,we use FE-safe software to analyze the fatigue failure.The risk compliance coefficients of various failure modes are calculated and classified according to the risk level.In this way,the service life of the LPG cylinder weld is determined.The presented method improves the safety risk assessment process of LPG cylinder and provides a good theoretical and practical basis for similar pressure vessel risk assessment.
