Numerical Simulation of Coal Spontaneous Combustion around a Borehole Induced by Negative Pressure Gas Drainage
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 ef...
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2021-01-01
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Series: | Geofluids |
Online Access: | http://dx.doi.org/10.1155/2021/3938243 |
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doaj-484028ff91074f60a2d4a0d592262ef72021-08-23T01:31:50ZengHindawi-WileyGeofluids1468-81232021-01-01202110.1155/2021/3938243Numerical Simulation of Coal Spontaneous Combustion around a Borehole Induced by Negative Pressure Gas DrainageYouxin Zhao0Qingjie Qi1Xinlei Jia2Yingjie Liu3Jingwen Zhang4Emergency Science Research AcademyEmergency Science Research AcademySchool of Safety Science and EngineeringEmergency Science Research AcademyEmergency Science Research AcademyThe 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.http://dx.doi.org/10.1155/2021/3938243 |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Youxin Zhao Qingjie Qi Xinlei Jia Yingjie Liu Jingwen Zhang |
spellingShingle |
Youxin Zhao Qingjie Qi Xinlei Jia Yingjie Liu Jingwen Zhang Numerical Simulation of Coal Spontaneous Combustion around a Borehole Induced by Negative Pressure Gas Drainage Geofluids |
author_facet |
Youxin Zhao Qingjie Qi Xinlei Jia Yingjie Liu Jingwen Zhang |
author_sort |
Youxin Zhao |
title |
Numerical Simulation of Coal Spontaneous Combustion around a Borehole Induced by Negative Pressure Gas Drainage |
title_short |
Numerical Simulation of Coal Spontaneous Combustion around a Borehole Induced by Negative Pressure Gas Drainage |
title_full |
Numerical Simulation of Coal Spontaneous Combustion around a Borehole Induced by Negative Pressure Gas Drainage |
title_fullStr |
Numerical Simulation of Coal Spontaneous Combustion around a Borehole Induced by Negative Pressure Gas Drainage |
title_full_unstemmed |
Numerical Simulation of Coal Spontaneous Combustion around a Borehole Induced by Negative Pressure Gas Drainage |
title_sort |
numerical simulation of coal spontaneous combustion around a borehole induced by negative pressure gas drainage |
publisher |
Hindawi-Wiley |
series |
Geofluids |
issn |
1468-8123 |
publishDate |
2021-01-01 |
description |
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. |
url |
http://dx.doi.org/10.1155/2021/3938243 |
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