scholarly journals Theoretical models for gas adsorption‐induced coal deformation under coal seam field conditions

2019 ◽  
Vol 7 (5) ◽  
pp. 1504-1513 ◽  
Author(s):  
Huihui Liu ◽  
Baiquan Lin ◽  
Wei Yang
Keyword(s):  
Coal Seam ◽  
Gas Adsorption ◽  
Theoretical Models ◽  
Field Conditions ◽  
Coal Deformation

scholarly journals Effect of damage on gas seepage mechanism in coal seam based on a coupled model

2019 ◽  
Vol 23 (3 Part A) ◽  
pp. 1323-1328
Author(s):  
Yi Xue ◽  
Zhengzheng Cao ◽  
Faning Dang ◽  
Songhe Wang ◽  
Mingming He ◽  
...  
Keyword(s):  
Coal Seam ◽  
Gas Adsorption ◽  
Damage Model ◽  
Mechanical Damage ◽  
Coupled Model ◽  
Gas Migration ◽  
Initial Stage ◽  
Coal Deformation ◽  
Gas Seepage ◽  
Coal Damage

Damage has a significant impact on gas migration in coal seam. In this paper, a coupled hydraulic-mechanical-damage model is established, which takes into account the coupling relationship among coal damage, gas seepage and coal deformation. The simulation results show that the damage of coal body has little effect on seepage characteristic in the initial stage, but the influence of damage on gas seepage is increasing with the increase of time. Both the distribution of gas pressure and the gas adsorption content of coal body have a significant change.

Theoretical Models To Predict Gas Adsorption Capacity on Moist Coal

2019 ◽  
Vol 33 (4) ◽  
pp. 2908-2914 ◽  
Author(s):  
Dong Chen ◽  
Zhihui Ye ◽  
Zhejun Pan ◽  
Yuling Tan ◽  
Hui Li
Keyword(s):  
Adsorption Capacity ◽  
Gas Adsorption ◽  
Theoretical Models

Modeling and Simulation of Coal Loading by Cutting Drum in Flat Seams

2016 ◽  
Vol 61 (2) ◽  
pp. 365-379 ◽  
Author(s):  
Piotr Gospodarczyk
Keyword(s):  
Coal Seam ◽  
Discrete Element Method ◽  
Modeling And Simulation ◽  
Theoretical Models ◽  
Kinematic Parameters ◽  
Coal Seams ◽  
Physical Systems ◽  
Efficient Simulation ◽  
Coal Cutting ◽  
Selection Of

Abstract This paper presents a methodology for modeling work of a coal shearer work in low longwall coal seams where the wall height does not exceed 1.5 m. In such conditions, an important issue is the process of loading the ore from shearer cutting drum on an armored face conveyor and selection of appropriate kinematic parameters to avoid choking. Discrete element method was used to model coal seam. This method allows for efficient simulation of physical systems composed of many separate components. Methods and algorithms based on existing theoretical models were developed to imitate coal cutting process. Main focus of analysis was put on coal stream movement for different variants of the shearer construction and kinematic parameters.

Transformation of the Triaxial Seepage Device for Measuring Deformation of Coal Containing Gas

2013 ◽  
Vol 477-478 ◽  
pp. 610-613
Author(s):  
Mei Yuan ◽  
Qing Hao Meng ◽  
Jiang Xu ◽  
Bo Bo Li ◽  
Yu Qin Du
Keyword(s):  
Coal Seam ◽  
Gas Migration ◽  
Coal Deformation ◽  
Gas Seepage

To explore the regularity of deformation and gas migration of coal seam, the author transmits signal of strain foil on coal samples in all directions by transforming oil plug, oil plug seal, heat shrink tubing and wire seal, based on the existing triaxial seepage device. We can complete coal deformation and gas seepage test with this device under different temperature, different stress, different gas stress and so on.

scholarly journals Investigation of Large-Diameter Borehole for Enhancing Permeability and Gas Extraction in Soft Coal Seam

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Yongwen Wang ◽  
Wanjun Yan ◽  
Zhongjiu Ren ◽  
Zhiqiang Yan ◽  
Ziwen Liu ◽  
...  
Keyword(s):  
Coal Seam ◽  
Shear Failure ◽  
Large Diameter ◽  
Gas Content ◽  
Gas Extraction ◽  
Extraction Area ◽  
Damage Area ◽  
Soft Coal ◽  
Coal Deformation ◽  
Soft Coal Seam

The efficiency of gas extraction from the soft coal seam with ultralow permeability is low. Gas extraction with large-diameter borehole is proposed to deplete gas content for preventing gas outburst disaster in this study. The fractures around the large borehole will enhance the permeability in the damage area to promote gas extraction. We established a damage-stress-seepage coupling model for large-diameter borehole gas extraction in soft coal seam. This mathematical model contains governing equations of gases sorption and transport, coal deformation, and damage, reflecting the coupling responses between gas and coal seam. The model is solved by the finite element method to simulate the gas drainage large-diameter borehole through roadway. Distributions of elastic modulus, damage area, and maximum principal stress in soft coal seam with different borehole diameters including 94 mm, 133 mm, 200 mm, and 300 mm are analyzed. The gas pressure, gas content, and effective extraction area in soft coal seam are discussed. Results show that the shear failure zone appears around the large-diameter borehole, and its permeability rises sharply. This opens up the gas transport channel and is conducive to the rapid extraction. It is confirmed that gas extraction using large-diameter borehole (300 mm) can greatly improve the efficiency of the gas preextraction in soft coal seam by increasing gas extraction rate. These provide a foundation for guiding the operation of gas extraction with large borehole from the soft coal seam in the field.

scholarly journals Influence Law of Interbedded Strata and Their Collapse on the Mining of Extremely Thick Coal Seam under Goaf

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Chunxu Ji ◽  
Yongkang Yang ◽  
Xingyun Guo ◽  
Tianhe Kang ◽  
Zefeng Guo
Keyword(s):  
Coal Seam ◽  
Water Inrush ◽  
Theoretical Models ◽  
Pressure Control ◽  
Future Research ◽  
Simulation Experiments ◽  
Thick Coal Seam ◽  
Movement Characteristics ◽  
Mining Pressure ◽  
The Stability

Interbedded strata and their collapse are vital to mining pressure control for extremely thick coal seam under goaf. To ensure the stability of the support and to avoid roof collapse, some traditional underground pressure theoretical models had been widely used in the control of surrounding rock and the selection of support. However, one of the challenges for extremely thick coal seam under goaf is that the abnormal disasters, such as support crushing and water inrush that were occurring frequently. To solve this problem, the movement characteristics of overburden rocks during the mining of extremely thick coal seam under the conditions of the interlayer thickness of 5 m and 40 m were studied by using the similar simulation experiments, while the numerical simulation experiments were carried out for the interval between coal seams of 15 m and 60 m, respectively. Finally, the structure and mechanical transfer mechanism of overburden in stope under different thickness interbedded strata were analyzed dynamically, and the condition of full-thickness connection between upper goaf and lower goaf and corresponding judgment criteria are obtained. These results can guide future research on the mechanical of extremely thick coal seam under goaf, which can provide a theoretical basis and engineering reference for similar projects.

scholarly journals Comparative Experiment Study on Nitrogen Injection and Free Desorption of Methane-Rich Bituminous Coal Under Triaxial Loading

2017 ◽  
Vol 62 (4) ◽  
pp. 911-928 ◽  
Author(s):  
Lei Zhang ◽  
Zhiwei Ye ◽  
Jun Tang ◽  
Dingyi Hao ◽  
Cun Zhang
Keyword(s):  
Coal Seam ◽  
Coalbed Methane ◽  
Gas Adsorption ◽  
Injection Pressure ◽  
Rapid Decline ◽  
Time Interval ◽  
Adsorption Model ◽  
Adsorption Phenomenon ◽  
Nitrogen Injection ◽  
Displacement Ratio

Abstract As a kind of associated geological gas, coalbed methane (CBM) is mainly adsorbed in the coal seam. The coal-methane adsorption phenomenon can be described by Langmuir monolayer adsorptio n model, BET multilayer adsorption model and the Theory of Volume Filling of Micropore (TVFM), whereas the binary gas adsorption phenomenon can be described by the extended Langmuir Model. For the CBM in the low permeability coal seam, the amount of gas released by direct drainage is relatively limited, which cannot eliminate the gas explosion and outburst hazards. Gas injection is an effective method to promote methane drainage. In this paper, the free desorption and nitrogen injection displacement experiments are comparatively analyzed, which allows verifying the effectiveness of nitrogen injection’s enhancement to gas drainage. The experiment of injecting nitrogen gas into the coal body shows that the coal fracture can be maintained or expanded by the injected gas pressure so that more methane can be released. The nitrogen injection has a higher time efficiency than that of free desorption as well. The displacement ratio of N2/CH4 is in the range of 1-3. Both the injection pressure and confining pressure affect the displacement ratio. The analysis of the desorbed gas components shows that the relationship between the methane component and gas flooding time is an “inverted S” shape curve, and the appropriate time for the methane collection can be inferred by the time interval of the rapid decline of the curve.

scholarly journals Thermal Imager Range: Predictions, Expectations, and Reality

Sensors ◽  
2019 ◽  
Vol 19 (15) ◽  
pp. 3313 ◽  
Author(s):  
Dragana Perić ◽  
Branko Livada ◽  
Miroslav Perić ◽  
Saša Vujić
Keyword(s):  
Long Range ◽  
Imaging System ◽  
Weather Conditions ◽  
Theoretical Models ◽  
Field Conditions ◽  
Design Parameters ◽  
Surveillance Systems ◽  
Thermal Imager ◽  
Adverse Weather ◽  
Thermal Imagers

Imaging system range defines the maximal distance at which a selected object can be seen and perceived following surveillance task perception criteria. Thermal imagers play a key role in long-range surveillance systems due to the ability to form images during the day or night and in adverse weather conditions. The thermal imager range depends on imager design parameters, scene and transmission path properties. Imager range prediction is supported by theoretical models that provide the ability to check range performance, compare range performances for different systems, extend range prediction in field conditions, and support laboratory measurements related to range. A condensed review of the theoretical model’s genesis and capabilities is presented. We applied model-based performance calculation for several thermal imagers used in our long-range surveillance systems and compared the results with laboratory performance measurement results with the intention of providing the range prediction in selected field conditions. The key objective of the paper is to provide users with reliable data regarding expectations during a field mission.

Experimental Study on Gas Pressure Effects on Gas Desorption Characteristic of Coal Seam

2013 ◽  
Vol 318 ◽  
pp. 367-370 ◽  
Author(s):  
Lin Chao Dai ◽  
Da Yong Lu ◽  
Zhen Liu
Keyword(s):  
Coal Seam ◽  
Gas Adsorption ◽  
Experimental System ◽  
Gas Pressure ◽  
Pressure Effects ◽  
Gas Content ◽  
Equilibrium Pressure ◽  
Gas Desorption ◽  
Exploitation And Utilization ◽  
The Impact

To further explore the impact of gas pressure on gas desorption and flowing law, the gas desorption experimental system designed autonomously is used to carry out studies on gas desorption experiment under different gas pressures. By data fitting, the relationship between gas desorption quantity and time is obtained and also established the model for gas desorption. The results show that: the gas desorption quantity curves is "The first half rises sharply, the latter half segment is gently rising and eventually becomes stabilized", and when the gas adsorption equilibrium pressure is the greater, the gas desorption amount is greater. And the formula can describe the gas desorption law well, the correlation coefficient R2 is above 0.97. The study provides an important theory reference to coal and gas outburst prediction, coal seam gas content prediction and its exploitation and utilization.

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