scholarly journals Disastrous Mechanism and Concentration Distribution of Gas Migration in Fully Mechanized Caving Stope in Wuyang Coal Mine

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Li Chong ◽  
He Sifeng ◽  
Xu Zhijun
Keyword(s):  
Coal Mine ◽  
Concentration Distribution ◽  
Spontaneous Combustion ◽  
Concentration Field ◽  
Gas Migration ◽  
Coal Spontaneous Combustion ◽  
Gas Drainage ◽  
Gas Concentration ◽  
Research Results ◽  
Working Face

The overrunning disaster of harmful gas tends to occur in the working face in thick coal seam with high gas concentration, as the fully mechanized caving stope has the characteristics of high mining intensity, high remnant coal, and high gas content. Therefore, the disastrous mechanism and concentration distribution of gas migration in fully mechanized caving stope are the theoretical basis for gas control scheme. Based on the 7607 working face in Wuyang coal mine, the gas emission quantity in working face is comprehensively analyzed by field measurement in this paper. The gas leakage field, oxygen concentration field, and gas concentration field in 7607 working face are simulated by establishing the equal proportional numerical model. Due to the increase of air leakage in working face caused by the high alley pumping drainage, the risk of coal spontaneous combustion is also analyzed, when gas extraction in goaf is carried out. The research results show that the gas drainage technology in high drainage roadway has a remarkable effect on the gas overrunning phenomenon. The gas concentration near the upper corner of the working surface has been reduced from 0.7%-1% to 0.5%. At the same time, it is necessary to pay attention to the risk of coal spontaneous combustion in the goaf for gas drainage in the high drainage roadway. The width of the oxidation zone in the goaf is about 25 m deeper than that before the drainage. Research results provide the references for gas control technology and coal spontaneous combustion prevention in similar working faces.

scholarly journals Study on the Optimization of a Gas Drainage Borehole Drainage Horizon Based on the Evolution Characteristics of Mining Fracture

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4499
Author(s):  
Tengteng Li ◽  
Bing Wu ◽  
Baiwei Lei
Keyword(s):  
Coal Mine ◽  
Gas Drainage ◽  
Gas Concentration ◽  
Low Level ◽  
Working Face ◽  
Evolution Characteristics ◽  
Gas Disaster ◽  
Fracture Area ◽  
High Level ◽  
Initial Change

Gas disaster restricts the safety development of coal mine. The technology of high-level borehole gas drainage is an important means to reduce the gas concentration in goaf. In order to determine the best position of the end of gas drainage hole, in this paper, based on the geological conditions of Xinyuan coal mine 31009 working face, a series of numerical simulation is carried out; and through the field test, the dynamic change of gas concentration in different height of borehole is monitored. The results show that: When the working face advances to different distances, there are four characteristic distribution areas in the horizontal direction: the fracture area of the original rock stratum, fracture channel generation and development area, fracture channel mature area and fracture channel closure area. Although the drilling horizon is different, the change of gas concentration in drilling can be divided into four stages: gas stabilization stage, gas initial change stage, gas fluctuation stage and gas re-stabilization stage. The variation of borehole concentration can reflect the evolution characteristics of fracture area. The response time of gas change in different layers is also different. In the gas initial change stage and the gas re-stabilization stage, the low-level borehole first responds. The response of gas change in high-level drilling is a long process, so the effect of high-level drilling is better than that of low-level drilling. For 31009 working face, the best gas drainage layer is 32m, and the field gas drainage has achieved good practical results. This study can provide some guidance for the prevention and control of gas disaster in goaf.

Gas Concentration Distribution Law in the Roadway after Coal and Gas Outburst

2015 ◽  
Vol 713-715 ◽  
pp. 314-318
Author(s):  
Chun Li Yang ◽  
Yi Liang Zhao ◽  
Xiang Chun Li ◽  
Yang Yang Meng ◽  
Fei Fei Zhu
Keyword(s):  
Concentration Distribution ◽  
Correlation Coefficients ◽  
Coal And Gas Outburst ◽  
Gas Emission ◽  
Distribution Law ◽  
Gas Concentration ◽  
Research Results ◽  
Gas Outburst ◽  
Whole Process ◽  
Secondary Disasters

Gas emission happens after coal and gas outburst, and it could cause secondary disasters in the roadway. Therefore it is necessary to research gas concentration distribution law in the roadway after coal and gas outburst, and theoretical basis for avoiding the occurrence of secondary disasters could be provided. Based on the above, Fluent is used to simulate gas concentration distribution law in the roadway during outburst. The research results show that gas velocity of the initial stage is larger in the whole process of gas outburst and gas emission impacts opposite walls in the form of jet in the roadway intersection. The flow changes direction and moves along the main airway and return airway. It produces countercurrent along the main airway. Because the pressure in the main airway is high, gas migration velocity becomes zero after a certain distance and is "back" to return airway. The higher the outburst velocity is, the longer the flow length is. Gas concentration variation with two kinds of different outburst intensities and position are regressed and it shows that correlation coefficients of power function are the highest. The research results have a certain theoretical value to prevent the occurrence of secondary disasters after coal and gas outburst.

scholarly journals Prediction Model for Spontaneous Combustion of Coal around Boreholes Using Bedding Gas Drainage

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Youxin Zhao ◽  
Qingjie Qi ◽  
Xinlei Jia
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Negative Pressure ◽  
Spontaneous Combustion ◽  
Orthogonal Test ◽  
Gas Drainage ◽  
Positive Linear Correlation ◽  
Drainage Hole ◽  
Spontaneous Combustion Of Coal ◽  
Fractured Coal

To accurately and reliably predict the time of spontaneous combustion of fractured coal around a borehole induced by gas drainage along the seam, this study performed an orthogonal test taking the No. 10 Coal Mine of Pingdingshan as the research object, in terms of the suction negative pressure and coal seam buried depth. COMSOL Multiphysics was used to model the orthogonal test results, and a multielement statistical analysis of four factors and their relationships with the spontaneous combustion of coal around the borehole and a single-factor analysis in line with the site conditions were performed on the modeling results through multiple regression. The results showed a nonlinear regression relationship between the sealing hole length, sealing hole depth, negative pressure, and coal seam depth and the spontaneous combustion of the coal around the gas drainage borehole; the prediction regression model is significant. Taking the field gas drainage in the No. 10 Coal Mine of Pingdingshan as an example, the relationship between the time of spontaneous combustion of gas drainage and the drainage pressure follows a power of two. When the drainage negative pressure is less than 45 kPa, the coal around the borehole is more likely to undergo spontaneous combustion with increasing pressure, and the sealing hole length has a positive linear correlation with the time of spontaneous combustion of the coal around the borehole. When the sealing hole length is 23 m, the time of spontaneous combustion of the coal around the gas drainage hole is >500 days, and the coal around the borehole does not easily undergo spontaneous combustion. When the sealing depth is 15 m, the time of spontaneous combustion of the coal around the gas drainage hole is 76 days, which is most likely to cause spontaneous combustion.

scholarly journals Anomaly Detection for Time Series with Difference Rate Sample Entropy and Generative Adversarial Networks

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Keke Gao ◽  
Wenbin Feng ◽  
Xia Zhao ◽  
Chongchong Yu ◽  
Weijun Su ◽  
...  
Keyword(s):  
Time Series ◽  
Anomaly Detection ◽  
Normal Mode ◽  
Coal Mine ◽  
Spontaneous Combustion ◽  
Sample Entropy ◽  
Generative Adversarial Networks ◽  
Detection Accuracy ◽  
Gas Concentration ◽  
Adversarial Networks

The spontaneous combustion of residual coals in the mined-out area tends to cause an explosion, which is one kind of severe thermodynamic compound disaster of coal mines and leads to serious losses to people's lives and production safety. The prediction and early warning of coal mine thermodynamic disasters are mainly determined by the changes of the index gas concentration pattern in coal mine mined-out areas collected continuously. The time series anomaly pattern detection method is mainly used to reach the state change of gas concentration pattern. The change of gas concentration follows a certain rule as time changes. A great change in the gas concentration indicates the possibility of coal spontaneous combustion and other disasters. To emphasize the features of collected maker gas and overcome the low anomaly detection accuracy caused by the inadequate learning of the normal mode, this paper adopted a method of anomaly detection for time series with difference rate sample entropy and generative adversarial networks. Because the difference rate entropy feature of abnormal data was much larger than that of normal mode, this paper improved the calculation method of the abnormal score by giving different weights to the detection points to enhance the detection rate. To verify the effectiveness of the proposed method, this paper employed simulation models of the mined-out area and adopted coal samples from Dafosi Coal Mine to carry out experiments. Preliminary testing was performed using monitoring data from a coal mine. The experiment compared the entropy results of different time series with the detection results of generative adversarial networks and automatic encoders and showed that the method proposed in this paper had relatively high detection accuracy.

The Optimum Arrangement of Working Face Ventilation System for Coal Mine

2012 ◽  
Vol 482-484 ◽  
pp. 1691-1694
Author(s):  
Ning He ◽  
Qiu Ju Ma ◽  
Yu Zhu Shi
Keyword(s):  
Coal Mine ◽  
Ventilation System ◽  
Dynamics Simulation ◽  
Practical Significance ◽  
Gas Migration ◽  
Optimal Layout ◽  
High Concentration ◽  
Working Surface ◽  
Working Face ◽  
Optimum Arrangement

It was most effective and practical that using computational fluid dynamics simulation to analyze the distribution of flow field in gob for studying optimal layout scheme of the working face ventilation system. In this paper, numerical simulation was applied for studying the migration laws and high concentration of gas gathering area of N1201 working face in Tunliu Coal Mine; the gob of robbing working surface gas migration laws and high concentration of gas gathering area was obtained; the optimum arrangement of ventilation system for the working face was given. The conclusions had a certain theoretical value and practical significance for controlling the working face gas.

Study on the Relationship of the Quantity of CO2 Produced and the Wind Speed

2014 ◽  
Vol 881-883 ◽  
pp. 1638-1641
Author(s):  
Xian Long Sun ◽  
Er Xin Gao ◽  
Hong Fen Zhang ◽  
Qiang Wang ◽  
Li Juan Li
Keyword(s):  
Experimental Data ◽  
Wind Speed ◽  
Coal Seam ◽  
Coal Mine ◽  
Laboratory Experiments ◽  
Spontaneous Combustion ◽  
Geothermal Heat ◽  
Research Results ◽  
Relationship Of ◽  
The Relationship

Based on the geological and the experimental data of the13#coal seam of Sun-Cun Coal Mine, the relationship curve between the geothermal heat in Sun-Cun coal mine and experimental wind speed has been fit out.According this and the laboratory experiments,the relational expression between the quantity of CO2 produced in the period of spontaneous combustion and the wind speed in the coal mine has been developed. The research results show that when the wind speed exceeds 2m/s,the quantity of CO2 produced has a sharp rising tendency.

scholarly journals Oxygen Distribution and Air Leakage Law in Gob of Working Face of U+L Ventilation System

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Xiaowei Zhai ◽  
Bo Wang ◽  
Shangrong Jiang ◽  
Weixia Zhang
Keyword(s):  
Oxygen Concentration ◽  
Spontaneous Combustion ◽  
Ventilation System ◽  
Burial Depth ◽  
Air Leakage ◽  
Coal Spontaneous Combustion ◽  
Working Face ◽  
Air Intake ◽  
And Control ◽  
The Relationship

In order to prevent and control coal spontaneous combustion effectively in the gob of U+L working face, the 30105 working face of Hanglaiwan mine was taken as the research object. The relationship models between oxygen concentration and burial depth of the two tunnels in the gob of U+L working face were established. The distribution of oxygen in the gob of the working face of U+L ventilation system was studied by field observation combined with numerical simulation. The results show that the air leakage in the gob is serious. There are a number of fluctuation areas where the oxygen concentration first decreases and then increases in the air intake side of the gob. The oxygen concentration peaked at 100m, 175m, and 245m, respectively, from the intake side of the gob. In the same position of the gob depth, the air leakage intensity on the intake side is generally higher than that on the return side, and the oxygen concentration on the intake side of the gob is slower than the return side. Oxygen concentration maintains at 5.09% when the depth of gob reaches 400m. Measures to prevent coal spontaneous combustion should be strengthened in the air intake side.

scholarly journals Influence of Air Supply on Coal Spontaneous Combustion During Support Withdrawal in Fully Mechanized Coal Mining and its Prevention

2021 ◽  
Author(s):  
Xiaowen Zhang ◽  
Xihua Zhou ◽  
Gang Bai ◽  
Cheng Wang
Keyword(s):  
Spontaneous Combustion ◽  
Characteristic Temperature ◽  
Effect Of Temperature ◽  
Withdrawal Period ◽  
Coal Spontaneous Combustion ◽  
Hydrocarbon Gases ◽  
Working Face ◽  
Air Supply ◽  
Spontaneous Combustion Of Coal ◽  
Temperature Programmed

Abstract It is important to study the oxidation characteristics of coal samples under different air supply rates to prevent spontaneous combustion of coal, particularly when the air supply rate at the working face needs to be changed during support withdrawal. In this work a self-designed temperature-programmed experimental device was used to study the change laws of various index gases released during the spontaneous combustion of coal under various air supply conditions. The study focused on the analysis of the low-temperature (30–200 ℃) oxidation stage, the increase in air supply, and the concentration change process of four hydrocarbon gases (C2H6, C3H8, C2H4, and C2H2) generated by the coal sample. The change law of the CO generation rate under the combined effect of temperature and air supply was analyzed, and surface fitting was performed to determine the characteristics of phased changes. Based on the working face parameters of the Yangchangwan Coal Mine, this study predicted the CO concentration at the upper corner of the working face at the characteristic temperature of coal spontaneous combustion during the withdrawal period. The paper summarizes comprehensive safety measures that can help prevent spontaneous combustion during the withdrawal period.

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