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.

Study on the Relation between the Deep and the Spontaneous Combustion of Coal Seam

2014 ◽  
Vol 852 ◽  
pp. 821-825 ◽  
Author(s):  
Jian You Di ◽  
Er Xin Gao ◽  
Xian Long Sun ◽  
Chang Qing Sun ◽  
Yu Li Chen
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Laboratory Experiments ◽  
Spontaneous Combustion ◽  
Geothermal Gradient ◽  
Laboratory Analysis ◽  
Spontaneous Combustion Of Coal ◽  
Mine Depth ◽  
Relationship Of ◽  
The Relationship

Based on the data and laboratory analysis of Sun-Cun Coal Mine, the relationship between the geothermal gradient and the depth of mine in Suncun Coal Mine has been developed. According to this and the laboratory experiments, the relationship between spontaneous combustion period of coal seam and the depth of the mine has been obtained in this article. The results show that the law of coal seam spontaneous combustion period and the mine depth in accordance with the relationship of the gauss curve expression and when the coal mine depth is around 1000 m, the coal seam spontaneous combustion period shortened dramatically. This law should be pay more attention to.

scholarly journals Numerical Simulation of Coal Spontaneous Combustion around a Borehole Induced by Negative Pressure Gas Drainage

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Youxin Zhao ◽  
Qingjie Qi ◽  
Xinlei Jia ◽  
Yingjie Liu ◽  
Jingwen Zhang
Keyword(s):  
Oxygen Concentration ◽  
Negative Pressure ◽  
Spontaneous Combustion ◽  
Combustion Process ◽  
Extraction Process ◽  
Gas Extraction ◽  
Growth Trend ◽  
Gas Drainage ◽  
Gas Seepage ◽  
Spontaneous Combustion Of Coal

The suction negative pressure is an important factor affecting the spontaneous combustion of coal around a borehole. Because the mechanism of suction negative pressure in the gas extraction process remains unclear, a constant suction negative pressure is often used in coal mines, leading to a low efficiency of gas extraction in deep coal seams. Moreover, the coal body easily undergoes spontaneous combustion during the extraction process, which is not conducive to safe mining. To study the effect of the suction negative pressure near the end sealing section, a numerical model of the combustion process around a borehole under the influence of suction negative pressure was established using COMSOL. The variation laws of the gas seepage velocity, oxygen concentration, and coal temperature in the borehole cycle were analyzed, and the gas suction negative pressure under different sealing parameters was optimized to ensure efficient gas extraction and prevent the spontaneous combustion of coal. The results showed that the negative pressure of extraction provides the power required for gas seepage into the borehole, and the gas flow rate increases with increasing negative pressure of extraction, exhibiting a linear growth trend. The range of the coal suffocation zone around the sealing section decreases with the increase in the negative pressure. With the extension of the gas extraction time, the oxygen concentration decreases rapidly, and the inflection point advances with the increase in the negative pressure. When the negative pressure of gas extraction is <40 kPa, the range of the high-temperature area around the block increases with the negative pressure of gas extraction. Based on the present situation of the spontaneous combustion induced by gas drainage in the Pingdingshan No. 10 Coal Mine, different sealing parameters should be set with different negative pressures of extraction, and the negative pressure of extraction should not exceed −18 kPa when the sealing depth is 20 m and the sealing length is 8 m in the 24130 working face. These parameter settings can help effectively prevent spontaneous combustion during the extraction process.

scholarly journals The Influence of the Sample Preparation on the Result of Coal Propensity to Spontaneous Combustion in the High-temperature Adiabatic Method

2021 ◽  
Vol 1 (2) ◽  
Author(s):  
Dariusz OBRACAJ ◽  
Marek KORZEC ◽  
Tien Tung VU
Keyword(s):  
High Temperature ◽  
Coal Seam ◽  
Spontaneous Combustion ◽  
Spontaneous Heating ◽  
Mine Fire ◽  
Mine Fires ◽  
Technical Factors ◽  
Spontaneous Combustion Of Coal ◽  
Seam Mining ◽  
Very High

The liability of coal to spontaneous combustion is the principal cause of mine fires. Spontaneouscombustion is one of the main threats in Polish and Vietnamese coal mines. The article presents an analysisof the spontaneous combustion of coal in mines of both countries. It is related to the natural prone of coalto spontaneous heating and consequently to its self-ignition. Despite the relevant recognition of themethods of preventing this threat, in mines, spontaneous combustion occurs during the exploitation ofcoal seams with low and very high self-ignition tendency. Apart from the technical factors related to thedesign of coal seam mining, the properties of coal have a significant impact on the occurrence ofspontaneous combustion. Their correct recognition is essential to the precautions against spontaneouscombustion for minimalizing the risk of a mine fire. Therefore, it is necessary to study the factorsinfluencing the propensity of coal to spontaneous heating. A review of the methods used to determine thepropensity of coal to spontaneous combustion is presented in the article. Based on the high-temperaturemethod of determining the propensity of coals to spontaneous combustion, the influence of selectedfactors related to samples' preparation for testing on the determination result was investigated. Theinfluence of the fractional decomposition and the moisture content in the prepared samples on thedetermination result was demonstrated. The presented research results may improve research proceduresfor determining the propensity of coal to spontaneous combustion.

Gob coal mine tunnel temperature changes caused by spontaneous combustion of coal online monitoring

2014 ◽  
Vol 40 (5) ◽  
pp. 399-401 ◽  
Author(s):  
李佳奇 LI Jiaqi ◽  
倪建明 NI Jianming ◽  
陈贵 CHEN Gui ◽  
刘文革 LIU Wenge ◽  
田驰 TIAN Chi ◽  
...  
Keyword(s):  
Coal Mine ◽  
Online Monitoring ◽  
Spontaneous Combustion ◽  
Temperature Changes ◽  
Spontaneous Combustion Of Coal

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 Reasonable Scope of Kilometer Drilling in Lower Layer of Extrathick Coal Seam: A Case Study of Tingnan Coal Mine, China

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Delong Zou ◽  
Xiang Zhang
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Lower Layer ◽  
Maximum Depth ◽  
Support Pressure ◽  
Directional Drilling ◽  
Pressure Relief ◽  
Gas Drainage ◽  
Working Face ◽  
Fracture Development

When stratified mining is adopted in high-gas and extrathick coal seam, a large amount of pressure-relief gas of the lower layer flows into the upper layer goaf along the cracks in the layer, resulting in upper layer working face to frequently exceed the gas limit. And ordinary drilling can no longer meet the requirements of the pressure-relief gas drainage of the lower layer. The 205 working face of Tingnan Coal Mine is taken as the test background in this paper, and based on the “pressure-relief and flow-increase” effect of the lower layer under the action of mining stress during the upper layer mining, the gas drainage of kilometer directional drilling in lower layer is studied. According to the distribution characteristics of support pressure before and after the working face, the pressure-relief principle, fracture development characteristics, and gas migration law of the lower layered coal body are analyzed in the process of advancing the upper layered working face in the extrathick coal seam with high gas. The maximum depth of goaf damage is calculated theoretically, and the Flac3D numerical simulation of the failure deformation of the 205 working face floor is carried out. It is found that the maximum depth of plastic failure of the lower layer is about 13 m. According to the plastic deformation of the lower layer under different vertical depths and the movement of coal and rock mass, it is determined that the reasonable range of kilometer directional drilling in the lower layer is 6–9 m below the floor vertical depth. From 15 m to 45 m in the two parallel grooves, there is no fracture failure with a sharp increase or decrease in the displacement in the local range. Meanwhile, in this part, the roof falling behind is not easy to compaction, and the displacement of the floor is large, which does not cause plastic damage. The degree of pressure relief is more sufficient, and the permeability of the lower layer is good. Therefore, drilling should be arranged as much as possible along the working face in this tendency range. The determination of reasonable arrangement range of kilometer directional drilling in extrathick coal seam provides reference index and theoretical guidance for industrial test of working face and also provides new ideas for gas control of stratified mining face in high-gas and extrathick coal seam.

The Relationship between the Period of Spontaneous Combustion and the Wind Speed

2014 ◽  
Vol 496-500 ◽  
pp. 613-616
Author(s):  
Xian Long Sun ◽  
Er Xin Gao ◽  
Qiang Wang ◽  
Shan Shan Xu ◽  
Chun Yuan Li
Keyword(s):  
Experimental Data ◽  
Wind Speed ◽  
Coal Seam ◽  
Coal Mine ◽  
Coal Sample ◽  
Laboratory Experiments ◽  
Spontaneous Combustion ◽  
Geothermal Heat ◽  
Research Results ◽  
The Relationship

Based on the geological and the experimental data of the 13# 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 period of spontaneous combustion in coal sample and the wind speed has been developed. The research results show that the curve of wind speed and the spontaneous combustion period fitted quadratic polynomial forms.

Experimental Research of Three-Phase Foam Fire-Fighting Technology in 7312-2 Caving Face Prevention Goal of a Coal Mine

2012 ◽  
Vol 594-597 ◽  
pp. 2257-2261
Author(s):  
Liu Jian ◽  
Ming Ming Liu ◽  
Zhen Hua Xie
Keyword(s):  
Fly Ash ◽  
Experimental Research ◽  
Coal Mine ◽  
Spontaneous Combustion ◽  
Fire Fighting ◽  
Laboratory Studies ◽  
Three Phase ◽  
Safety Production ◽  
Spontaneous Combustion Of Coal ◽  
Environmental Prevention

Spontaneous combustion of coal is a serious threat to the normal working of the mine and the safety of miners, the research to prevent spontaneous combustion of coal has a great significance. Technology based on the three-phase bubble theory, combined with characteristics of coal of 7312-2 caving face of a coal mine in Xuzhou, using laboratory studies to determination the fly ash , Wong and a variety of surfactant , then determining the formula of three-phase foam which is fit for a coal mine coal, it can restrain goal spontaneous combustion effectively and beneficial to safety production and environmental prevention.

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