Nitrogen injection fire preventing and extinguishing method for goaf in working face withdrawing period

Abstract

The method comprises the steps that a plurality of supporting plates are arranged in the width direction of the working face at equal intervals, the supporting plates are all located between every two adjacent hydraulic supports, after the working face retracts by a certain distance, holes are drilled from a heat dissipation zone to an oxidation zone, and the drilling distance meets the nitrogen injection requirement of the goaf; the supporting plate is detachably connected with three nitrogen injection pipes at equal intervals in the height direction, the nitrogen injection pipes are matched with the corresponding drill holes, the ends, deviating from the supporting plate, of all the nitrogen injection pipes are inserted into the corresponding drill holes, then the other ends of the nitrogen injection pipes are connected with the supporting plate, and then all the nitrogen injection pipes are connected with nitrogen supply equipment. The nitrogen supply device injects liquid nitrogen or nitrogen into the oxidation zone through the nitrogen injection pipe, then rapid nitrogen injection of the oxidation zone is achieved in the height direction and the width direction of the goaf, the nitrogen injection uniformity of the oxidation zone of the goaf is guaranteed, the nitrogen is rapidly dispersed in the oxidation zone, and the fire preventing and extinguishing effect of nitrogen injection of the goaf during the working face withdrawing period is improved.

Description

Technical Field

[0001] The invention relates to the field of coal mine safety, in particular to a method for preventing and extinguishing fire by injecting nitrogen into a goaf during the withdrawal of a working face. Background Art

[0002] Coal mine goafs are cavities or hollows formed after coal is mined and transported away during the mining process. The coal mining machine and hydraulic support gradually move when the working face is withdrawn, and the area of ​​the goaf gradually increases. Due to the lack of support, the rock formations around the goaf are prone to movement and deformation, which eventually causes the goaf to collapse, and some air will enter the goaf, which can easily lead to spontaneous combustion of coal in the goaf.

[0003] In the prior art, the methods for preventing and extinguishing spontaneous combustion of coal in goafs mainly include grouting, nitrogen injection, and injection of fire prevention and extinguishing materials. Among them, nitrogen injection for fire prevention and extinguishing can not only quickly extinguish the fire area, but also suppress the explosion of combustible gas in the goaf, thereby improving the safety of the fire prevention and extinguishing process. Liquid nitrogen will absorb a large amount of heat when it is gasified in the goaf, lowering the temperature of the goaf and preventing and controlling the spontaneous combustion of the coal body in the goaf. The traditional nitrogen injection method mainly involves pre-buried pipelines from the air intake tunnel to the goaf, and injecting nitrogen into the oxidation zone of the goaf. As the working face retreats, the pre-buried pipelines are cut off section by section.

[0004] With regard to the above-mentioned related technologies, when the goaf collapses, the broken rocks and coal bodies in the oxidation zone are scattered irregularly and may be distributed in a direction parallel to the working face. Nitrogen is only injected through the pre-buried pipeline from the air intake tunnel to the goaf, which makes the nitrogen dispersion speed slow or unable to be dispersed to the entire oxidation zone area, thereby resulting in poor fire prevention and extinguishing effect in the goaf. Summary of the invention

[0005] In order to improve the fire prevention and extinguishing effect of nitrogen injection in goaf during the withdrawal of working face, the present application provides a nitrogen injection fire prevention and extinguishing method in goaf during the withdrawal of working face.

[0006] This application provides a method for nitrogen injection fire prevention and extinguishing in goaf during the withdrawal of the working face, which adopts the following technical solutions:

[0007] The nitrogen injection fire prevention and extinguishing method in the goaf during the withdrawal of the working face includes:

[0008] S1; a plurality of support plates are arranged at equal intervals along the width direction of the working face, and each support plate is located between two adjacent hydraulic supports and is fixedly connected to two adjacent hydraulic supports on both sides of the support plate;

[0009] S2: After the working face is withdrawn a certain distance, drilling is done from the heat dissipation zone of the goaf to the oxidation zone, and the drilling distance meets the nitrogen injection requirements of the goaf;

[0010] S3; the support plate is detachably connected with three nitrogen injection pipes at equal intervals along the height direction, and the nitrogen injection pipes are adapted to the corresponding drill holes, and the ends of all nitrogen injection pipes away from the support plate are inserted into the corresponding drill holes, and then the other ends of the nitrogen injection pipes are connected to the support plate together;

[0011] S4; all nitrogen injection pipes are connected to nitrogen supply equipment, and the nitrogen supply equipment injects liquid nitrogen or nitrogen gas into the oxidation zone through the nitrogen injection pipes;

[0012] S5; after the nitrogen injection is completed, the nitrogen injection pipes in the middle and top of the support plate are removed and pulled out from the borehole, and the nitrogen injection pipe at the bottom remains connected to the support plate;

[0013] S6: After the nitrogen injection pipe is separated from the borehole, the borehole is backfilled.

[0014] Optionally, an adjustment plate is provided at the connection between the nitrogen injection pipe and the support plate, the adjustment plate is rotatably connected to the support plate, the adjustment plate is provided with a through hole adapted to the nitrogen injection pipe, and bolts for locking and positioning the nitrogen injection pipe are threadedly connected on both sides of the adjustment plate.

[0015] Optionally, the nitrogen injection pipes are all connected to flow regulating valves.

[0016] Optionally, a bundle tube gas sampling device for monitoring the concentration of harmful gases is installed underground, and the bundle tubes of the bundle tube gas sampling device are pre-buried from the air intake tunnel to the goaf, and the bundle tubes are multi-section detachable structures.

[0017] Optionally, the size of the support plate is adapted to the space between two adjacent hydraulic supports.

[0018] In summary, the present application includes at least one of the following beneficial technical effects:

[0019] 1. The technical solution of the present application realizes distributed rapid nitrogen injection into the oxidation zone along the height and width directions of the goaf, ensures the uniformity of nitrogen injection into the oxidation zone of the goaf, enables nitrogen to be quickly dispersed in the oxidation zone area, and improves the fire prevention and extinguishing effect of nitrogen injection in the goaf during the withdrawal of the working face;

[0020] 2. By setting up a bundle tube gas sampling device, it is convenient to determine the concentration and content of harmful gases such as carbon monoxide and methane, and then determine the amount of nitrogen injection to ensure the fire prevention and extinguishing effect of nitrogen injection in the goaf;

[0021] 3. The adjusting plate is rotatably connected to the support plate, so that the nitrogen injection pipe can be connected to the adjusting plate at a certain angle in the horizontal direction, thereby ensuring the use requirements of the nitrogen injection pipe under different working conditions and improving the versatility of the method. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present application.

[0023] Figure 2 It is a schematic diagram of the connection structure between the nitrogen injection pipe and the regulating plate.

[0024] Explanation of the accompanying reference numerals: 1. working face; 2. support plate; 3. hydraulic support; 4. goaf; 5. heat dissipation zone; 6. oxidation zone; 7. nitrogen injection pipe; 8. nitrogen supply equipment; 9. adjustment plate; 91. through hole; 92. bolt; 10. bundle tube gas sampling device; 101. bundle tube; 11. air intake lane. DETAILED DESCRIPTION

[0025] The present application is further described in detail below in conjunction with all the accompanying drawings.

[0026] The embodiment of the present application discloses a method for preventing and extinguishing fire by injecting nitrogen into a goaf during the withdrawal of a working face.

[0027] Example

[0028] Reference Figure 1 and Figure 2 , the nitrogen injection fire prevention and extinguishing method in goaf area 4 during the withdrawal of the working face includes:

[0029] S1; multiple support plates 2 are arranged at equal intervals along the width direction of the working face 1, and the support plates 2 are located between two adjacent hydraulic supports 3, and are fixedly connected to two adjacent hydraulic supports 3 on both sides of the support plate 2. When the working face 1 is withdrawn, the support plate 2 can move with the movement of the hydraulic support 3;

[0030] S2; After the working face 1 is withdrawn a certain distance, according to the scope, shape, geological conditions and distribution of the oxidation zone 6 of the goaf 4, a hole is drilled from the heat dissipation zone 5 of the goaf 4 to the oxidation zone 6, and the drilling distance meets the nitrogen injection requirements of the goaf 4;

[0031] S3; the support plate 2 is detachably connected with three nitrogen injection pipes 7 at equal intervals in the height direction, and an adjustment plate 9 is provided at the connection between the nitrogen injection pipe 7 and the support plate 2. The adjustment plate 9 is provided with a through hole 91 adapted to the nitrogen injection pipe 7, and bolts 92 are threadedly connected on both sides of the adjustment plate 9; at the same time, the nitrogen injection pipe 7 is adapted to the corresponding drilled hole, and the end of all nitrogen injection pipes 7 away from the support plate 2 is inserted into the corresponding drilled hole, and then the other end of the nitrogen injection pipe 7 is passed through the corresponding through hole 91, and then the bolts 92 on both sides of the adjustment plate 9 are tightened to conflict with the nitrogen injection pipe 7, and the position of the nitrogen injection pipe 7 is positioned;

[0032] A bundle tube gas sampling device 10 for monitoring the concentration and composition of harmful gases is installed underground. The bundle tube 101 of the bundle tube gas sampling device 10 is pre-buried along the air intake tunnel 11 to the goaf 4. The bundle tube 101 is a multi-section detachable structure, such as a threaded connection commonly used for sampling. When the working face 1 withdraws, the length of the bundle tube 101 located in the goaf 4 gradually increases, and then a new bundle tube 101 is gradually connected at one end close to the bundle tube gas sampling device 10 to ensure gas sampling in the oxidation zone 6 and the heat dissipation zone 5 of the goaf 4. The analysis of the gas by the bundle tube gas sampling and analysis device includes: carbon monoxide concentration content analysis, methane concentration content analysis, ethylene concentration content analysis, acetylene concentration content analysis, etc., among which the most important is to collect and analyze carbon monoxide and methane, determine the content of the two, and then determine the amount of nitrogen injection to ensure the nitrogen injection fire prevention and extinguishing effect in the goaf 4;

[0033] S4; then connect all the nitrogen injection pipes 7 to the nitrogen supply equipment 8, and the nitrogen supply equipment 8 injects liquid nitrogen or nitrogen gas into the oxidation zone 6 through the nitrogen injection pipe 7, and then realizes rapid nitrogen injection into the oxidation zone 6 along the height direction and width direction of the goaf 4, thereby ensuring the uniformity of nitrogen injection into the oxidation zone 6 of the goaf 4, allowing nitrogen to be quickly dispersed in the oxidation zone 6 area, thereby improving the fire prevention and extinguishing effect of nitrogen injection in the goaf 4 during the withdrawal of the working face 1;

[0034] The nitrogen injection pipes 7 are all connected to flow control valves, such as ball valves, and the flow control valves can be adjusted according to the nitrogen injection amount of the goaf 4 during the nitrogen injection process to meet the fire prevention and extinguishing requirements of the nitrogen injection in the goaf 4;

[0035] When the borehole from the heat dissipation zone 5 to the oxidation zone 6 cannot be drilled vertically due to geological reasons and deflects in the horizontal direction, the nitrogen injection pipe 7 is connected to the adjustment plate 9 at an acute angle or an obtuse angle, and the adjustment plate 9 is rotatably connected to the support plate 2, so that the nitrogen injection pipe 7 can be connected to the adjustment plate 9 at a certain angle in the horizontal direction, thereby ensuring the use requirements of the nitrogen injection pipe 7 under different working conditions and improving the multi-applicability of the method;

[0036] S5; After the nitrogen injection is completed, the nitrogen injection pipe 7 in the middle and top of the support plate 2 is removed and pulled out from the borehole, and the nitrogen injection pipe 7 at the bottom remains connected to the support plate 2. The nitrogen injection pipe 7 at the bottom will not be bent or deformed due to gravity, and can be directly pulled out from the oxidation zone 6 when the hydraulic support 3 moves, thereby reducing the disassembly time and improving the efficiency of subsequent nitrogen injection operations;

[0037] Nitrogen injection will slightly increase the gas pressure in the goaf 4. The size of the support plate 2 is adapted to the space between two adjacent hydraulic supports 3, which can reduce the escape of inert gas and harmful gas from the goaf 4 to the working face 1 due to pressure changes, thereby ensuring safe production of the working face 1.

[0038] S6; After the nitrogen injection pipe 7 is separated from the borehole, the borehole is backfilled to fill the voids within the goaf 4 to enhance the stability of the formation.

[0039] During the gradual withdrawal of the working face 1, the hydraulic support 3 and the support plate 2 are moved periodically, and the above-mentioned nitrogen injection fire prevention and extinguishing method is repeated to ensure the fire prevention and extinguishing effect of nitrogen injection in the goaf 4 during the withdrawal of the entire working face 1.

[0040] The implementation principle of the nitrogen injection fire prevention and extinguishing method for the goaf 4 during the withdrawal of the working face in the embodiment of the present application is as follows: a plurality of support plates 2 are arranged at equal intervals along the width direction of the working face 1, and the support plates 2 are all located between two adjacent hydraulic supports 3. After the working face 1 is withdrawn a certain distance, holes are drilled from the heat dissipation zone 5 to the oxidation zone 6, and the drilling distance meets the nitrogen injection requirements of the goaf 4; the support plates 2 are detachably connected with three nitrogen injection pipes 7 at equal intervals along the height direction, and the nitrogen injection pipes 7 are adapted to the corresponding drill holes, and all nitrogen injection pipes 7 are away from the support plates 2. Insert one end of the nitrogen injection pipe 7 into the corresponding borehole, and then connect the other end of the nitrogen injection pipe 7 to the support plate 2, and then connect all the nitrogen injection pipes 7 to the nitrogen supply equipment 8. The nitrogen supply equipment 8 injects liquid nitrogen or nitrogen gas into the oxidation zone 6 through the nitrogen injection pipe 7, and then realizes rapid nitrogen injection into the oxidation zone 6 along the height direction and width direction of the goaf 4, ensuring the uniformity of nitrogen injection into the oxidation zone 6 of the goaf 4, so that nitrogen is quickly dispersed in the oxidation zone 6 area, and the fire prevention and extinguishing effect of nitrogen injection in the goaf 4 during the withdrawal of the working face 1 is improved. After the nitrogen injection is completed, the nitrogen injection pipes 7 on the middle and top of the support plate 2 are removed and pulled out of the borehole, and the nitrogen injection pipe 7 at the bottom remains connected to the support plate 2. After the nitrogen injection pipe 7 is separated from the borehole, the borehole is finally backfilled.

[0041] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. Nitrogen injection fire prevention and extinguishing method in goaf during working face withdrawal. It is characterized in that include: S1； A plurality of support plates (2) are arranged at equal intervals along the width direction of the working surface (1), wherein each support plate (2) is located between two adjacent hydraulic supports (3) and is fixedly connected to two adjacent hydraulic supports (3) on both sides of the support plate (2); S2; After the working face (1) is withdrawn a certain distance, a hole is drilled from the heat dissipation zone (5) of the goaf (4) to the oxidation zone (6), and the drilling distance meets the nitrogen injection requirements of the goaf (4); S3; the support plate (2) is detachably connected with three nitrogen injection pipes (7) at equal intervals in the height direction, the nitrogen injection pipes (7) are adapted to the corresponding drill holes, and the ends of all nitrogen injection pipes (7) facing away from the support plate (2) are inserted into the corresponding drill holes, and then the other ends of the nitrogen injection pipes (7) are connected to the support plate (2); S4; all nitrogen injection pipes (7) are connected to a nitrogen supply device (8), and the nitrogen supply device (8) injects liquid nitrogen or nitrogen gas into the oxidation zone (6) through the nitrogen injection pipe (7); S5; After the nitrogen injection is completed, the nitrogen injection pipe (7) in the middle and top of the support plate (2) is removed and extracted from the borehole, and the nitrogen injection pipe (7) at the bottom remains connected to the support plate (2); S6; After the nitrogen injection pipe (7) is separated from the borehole, the borehole is backfilled.

2. The method for preventing and extinguishing fire by injecting nitrogen into goaf during the withdrawal of working face according to claim 1, Features: An adjusting plate (9) is provided at the connection between the nitrogen injection pipe (7) and the support plate (2), the adjusting plate (9) is rotatably connected to the support plate (2), a through hole (91) adapted to the nitrogen injection pipe (7) is provided on the adjusting plate opening (9), and bolts (92) for locking and positioning the nitrogen injection pipe (7) are threadedly connected on both sides of the adjusting plate (9).

3. The method for preventing and extinguishing fire by injecting nitrogen into goaf during working face withdrawal according to claim 1, Features: The nitrogen injection pipes (7) are all connected to flow regulating valves.

4. The method for preventing and extinguishing fire by injecting nitrogen into goaf during working face withdrawal according to claim 1, Features: A bundled tube gas sampling device (10) for monitoring the concentration of harmful gases is installed underground. The bundled tube (101) of the bundled tube gas sampling device (10) is pre-buried from the air intake tunnel (11) to the goaf (4). The bundled tube (101) is a multi-section detachable structure.

5. The method for preventing and extinguishing fire by injecting nitrogen into goaf during working face withdrawal according to claim 1, Features: The size of the support plate (2) is adapted to the space between two adjacent hydraulic supports (3).

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