Nitrogen injection fire prevention and extinguishing method in goaf during working face retreat

Abstract

The application discloses a nitrogen injection fire prevention and extinguishing method for a goaf during a working face retreat, which comprises the following steps: multiple support plates are arranged at equal intervals along the width direction of the working face, the support plates are located between two adjacent hydraulic supports, drilling holes are drilled from a heat dissipation zone to an oxidation zone after the working face retreats by a certain distance, and the drilling hole distance meets the nitrogen injection requirements of the goaf; three nitrogen injection pipes are detachably connected to the support plates at equal intervals along the height direction, the nitrogen injection pipes are matched with the corresponding drilling holes, one end of all the nitrogen injection pipes is inserted into the corresponding drilling holes, the other end of the nitrogen injection pipes is connected to the support plates, all the nitrogen injection pipes are connected to a nitrogen supply device, the nitrogen supply device injects liquid nitrogen or nitrogen gas into the oxidation zone through the nitrogen injection pipes, and then rapid nitrogen injection is realized along the height direction and the width direction of the goaf, the nitrogen injection uniformity of the oxidation zone of the goaf is ensured, nitrogen gas is rapidly dispersed in the oxidation zone, and the fire prevention and extinguishing effect of the nitrogen injection of the goaf during the working face retreat is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coal mine safety, in particular to a nitrogen injection fire prevention and extinguishing method for a goaf during a working face retreat. BACKGROUND

[0002] A coal mine goaf is a cavity or hollow formed after coal is mined and removed during the coal mining process. The coal winning machine and hydraulic support gradually move during the working face retreat, and the goaf area gradually increases. Due to the lack of support, the rock strata around the goaf are prone to movement and deformation, eventually causing the goaf to collapse, and some air may enter the goaf, which may cause coal spontaneous combustion in the goaf.

[0003] In the prior art, the methods for preventing and extinguishing coal spontaneous combustion in a goaf mainly include grouting, nitrogen injection, and injection of fire prevention and extinguishing materials. Nitrogen injection can quickly extinguish the fire zone and inhibit the explosion of flammable gas in the goaf, improving the safety during the fire prevention and extinguishing process. Liquid nitrogen absorbs a large amount of heat when it vaporizes in the goaf, reducing the temperature of the goaf and preventing and controlling the spontaneous combustion of coal in the goaf. The traditional nitrogen injection method mainly involves pre-burying a pipeline from the air inlet roadway to the goaf and injecting nitrogen into the oxidation zone of the goaf. As the working face retreats, the pre-buried pipeline is cut off section by section.

[0004] In view of the above related technology, when the goaf collapses, the broken rock and coal in the oxidation zone scatter irregularly, which may be distributed parallel to the working face. Only by injecting nitrogen through the pre-buried pipeline from the air inlet roadway to the goaf can the nitrogen be dispersed slowly or cannot be dispersed to the entire oxidation zone, which results in poor fire prevention and extinguishing effect in the goaf. SUMMARY

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

[0006] The present application provides a nitrogen injection fire prevention and extinguishing method for a goaf during a working face retreat, which adopts the following technical solution:

[0007] The nitrogen injection fire prevention and extinguishing method for a goaf during a working face retreat comprises:

[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 fixedly connected to the two hydraulic supports adjacent to the two sides of the support plate;

[0009] S2. After the working face retreats a certain distance, drill holes from the heat dissipation zone to the oxidation zone of the goaf, 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. The nitrogen injection pipes are adapted to the corresponding drill holes. Insert the end of all nitrogen injection pipes away from the support plate into the corresponding drill hole, and then connect the other end of the nitrogen injection pipes to the support plate.

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

[0012] S5; After nitrogen injection is completed, remove the nitrogen injection pipes in the middle and top of the support plate and pull them out of the borehole, while keeping the nitrogen injection pipe at the bottom connected to the support plate.

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

[0014] Optionally, an adjusting plate is provided at the connection between the nitrogen injection pipe and the support plate. The adjusting plate is rotatably connected to the support plate. The adjusting plate has a through hole that matches the nitrogen injection pipe. Bolts for locking and positioning the nitrogen injection pipe are threaded on both sides of the adjusting plate.

[0015] Optionally, each of the nitrogen injection pipes is connected to a flow regulating valve.

[0016] Optionally, a bundled tube gas sampling device for monitoring the concentration of harmful gases is installed underground. The bundled tube of the bundled tube gas sampling device is pre-buried along the intake airway to the goaf area, and the bundled tube is a multi-section detachable structure.

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

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

[0019] 1. The technical solution of this application enables distributed and rapid nitrogen injection into the oxidation zone along the height and width directions of the goaf, ensuring the uniformity of nitrogen injection into the oxidation zone of the goaf, enabling nitrogen to disperse rapidly in the oxidation zone area, and improving the fire prevention and extinguishing effect of nitrogen injection into the goaf during the retreat of the working face.

[0020] 2. By setting up a bundled tube gas sampling device, it is easy to determine the concentration and content of harmful gases such as carbon monoxide and methane, and thus determine the amount of nitrogen to be injected, ensuring the effectiveness of nitrogen injection for fire prevention and extinguishing in the goaf.

[0021] 3. The adjusting plate and the support plate are rotatably connected, so that the nitrogen injection pipe can be tilted at a certain angle in the horizontal direction and connected to the adjusting plate, which ensures the use requirements of the nitrogen injection pipe under different working conditions and improves the versatility of this method. Attached Figure Description

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

[0023] Figure 2 is a schematic view of the connection structure of the nitrogen injection pipe and the adjusting plate.

[0024] BRIEF DESCRIPTION OF DRAWINGS 1, working face; 2, support plate; 3, hydraulic support; 4, goaf; 5, heat dissipation belt; 6, oxidation belt; 7, nitrogen injection pipe; 8, nitrogen supply equipment; 9, adjusting plate; 91, through hole; 92, bolt; 10, beam pipe gas sampling device; 101, beam pipe; 11, air inlet roadway. DETAILED DESCRIPTION

[0025] The application will be further described in detail below in combination with all the drawings.

[0026] The application discloses a nitrogen injection fire prevention and extinguishing method for a goaf during working face retreat.

[0027] Embodiment

[0028] Reference Figure 1 and Figure 2 The nitrogen injection fire prevention and extinguishing method for the goaf 4 during working face retreat comprises the following steps.

[0029] S1. A plurality of support plates 2 are arranged at equal intervals along the width direction of the working face 1, the support plates 2 are located between two adjacent hydraulic supports 3, and the support plates 2 are fixedly connected with the two hydraulic supports 3 adjacent to the two sides of the support plates 2, so that the support plates 2 can move along with the movement of the hydraulic supports 3 during the retreat of the working face 1;

[0030] S2. After the working face 1 retreats a certain distance, drill holes from the heat dissipation belt 5 to the oxidation belt 6 of the goaf 4 according to the range, shape, geological conditions and distribution of the oxidation belt 6 of the goaf 4, and the drilling distance meets the nitrogen injection requirement of the goaf 4;

[0031] S3. Three nitrogen injection pipes 7 are detachably connected to the support plate 2 at equal intervals along the height direction, adjusting plates 9 are arranged at the connection positions of the nitrogen injection pipes 7 and the support plate 2, the adjusting plates 9 are provided with through holes 91 matched with the nitrogen injection pipes 7, and bolts 92 are threadedly connected to the two sides of the adjusting plates 9; meanwhile, the nitrogen injection pipes 7 are matched with the corresponding drill holes, one end of each nitrogen injection pipe 7 is inserted into the corresponding drill hole, the other end of the nitrogen injection pipe 7 passes through the corresponding through hole 91, and the bolts 92 on the two sides of the adjusting plate 9 are tightened to abut against the nitrogen injection pipe 7, so as to position the nitrogen injection pipe 7;

[0032] A bundle tube gas sampling device 10 for monitoring the concentration and composition of harmful gases is installed in the well, the bundle tube 101 of the bundle tube gas sampling device 10 is pre-buried along the air inlet lane 11 to the goaf 4, the bundle tube 101 is a detachable structure, for example, the common thread connection of sampling. When the working face 1 is withdrawn, the length of the bundle tube 101 located in the goaf 4 gradually increases, and then the new bundle tube 101 is gradually connected at the end close to the bundle tube gas sampling device 10, which guarantees the gas sampling of 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 to determine their contents and then determine the nitrogen injection amount to guarantee the effect of nitrogen injection for fire prevention and extinguishment in the goaf 4;

[0033] S4; all the nitrogen injection pipes 7 are connected with 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 pipes 7, and then realizes rapid nitrogen injection of the oxidation zone 6 along the height direction and the width direction of the goaf 4, which guarantees the uniformity of the nitrogen injection of the oxidation zone 6 of the goaf 4, makes the nitrogen gas quickly disperse in the oxidation zone 6 region, and improves the effect of nitrogen injection for fire prevention and extinguishment in the goaf 4 during the withdrawal of the working face 1;

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

[0035] When the borehole of the heat dissipation zone 5 to the oxidation zone 6 cannot be vertically drilled due to geological reasons and the like, and the borehole is inclined in the horizontal direction, the nitrogen injection pipe 7 is connected with the adjusting plate 9 at an acute angle or an obtuse angle, the adjusting plate 9 is rotationally connected with the support plate 2, so that the nitrogen injection pipe 7 can be connected with the adjusting plate 9 at an angle in the horizontal direction, which guarantees the use requirements of the nitrogen injection pipe 7 under different working conditions and improves the multi-applicability of the method;

[0036] S5; after the nitrogen injection is completed, the nitrogen injection pipes 7 in the middle and the top of the support plate 2 are removed and taken out from the borehole, the nitrogen injection pipe 7 at the bottom remains connected with the support plate 2, the nitrogen injection pipe 7 at the bottom will not be bent and deformed due to gravity, and can be directly taken out from the oxidation zone 6 when the hydraulic support 3 moves, which reduces the disassembly time and improves the efficiency of subsequent nitrogen injection operation;

[0037] The nitrogen injection will slightly increase the air pressure in the goaf 4, the size of the support plate 2 is matched with the space between the adjacent two hydraulic supports 3, which can reduce the escape of inert gases and harmful gases from the goaf 4 to the working face 1 due to pressure changes, and guarantees the safety 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 in the goaf 4 and enhance the stability of the stratum.

[0039] During the gradual retreat of the working face 1, the hydraulic supports 3 and the support plates 2 are periodically moved, and the above-mentioned nitrogen injection fire prevention and extinguishing method is repeated, so as to guarantee the fire prevention and extinguishing effect of the nitrogen injection in the goaf 4 during the retreat of the working face 1.

[0040] The implementation principle of the nitrogen injection fire prevention and extinguishing method of the goaf 4 during the retreat of the working face according to 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 located between two adjacent hydraulic supports 3; after the working face 1 retreats a certain distance, drill holes are drilled from the heat dissipation zone 5 to the oxidation zone 6, and the distance of the drill holes meets the nitrogen injection requirement of the goaf 4; the support plates 2 are detachably connected with three nitrogen injection pipes 7 at equal intervals along the height direction, the nitrogen injection pipes 7 are matched with the corresponding drill holes, one end of all the nitrogen injection pipes 7 is inserted into the corresponding drill holes, the other end of the nitrogen injection pipes 7 is connected with the support plates 2, all the nitrogen injection pipes 7 are connected with 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 pipes 7, and then realizes rapid nitrogen injection to the oxidation zone 6 along the height direction and the width direction of the goaf 4, so as to guarantee the uniformity of the nitrogen injection to the oxidation zone 6 of the goaf 4, make the nitrogen gas rapidly disperse in the oxidation zone 6, and improve the fire prevention and extinguishing effect of the nitrogen injection in the goaf 4 during the retreat of the working face 1. After the nitrogen injection is completed, the middle and top nitrogen injection pipes 7 of the support plates 2 are removed and extracted from the drill holes, the bottom nitrogen injection pipe 7 remains connected with the support plate 2, after the nitrogen injection pipes 7 are separated from the drill holes, the drill holes are finally backfilled.

[0041] The above are preferred embodiments of the present application, which do not limit the protection scope of the present application, therefore: any equivalent changes made on the structure, shape and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A nitrogen injection method for fire prevention and extinguishing in the goaf during working face retreat, characterized in that, include: S1； Several support plates (2) are set at equal intervals along the width direction of the working surface (1). Each support plate (2) is located between two adjacent hydraulic supports (3) and is fixedly connected to the 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 along the height direction. The nitrogen injection pipes (7) are adapted to the corresponding drill holes. Insert one end of all the nitrogen injection pipes (7) away from the support plate (2) into the corresponding drill hole, and then connect the other end of the nitrogen injection pipes (7) to the support plate (2). S4; All nitrogen injection pipes (7) are connected to nitrogen supply equipment (8), which injects liquid nitrogen or nitrogen gas into the oxidation zone (6) through nitrogen injection pipes (7); S5; After nitrogen injection is completed, remove the nitrogen injection pipes (7) in the middle and top of the support plate (2) and pull them out of the borehole, while keeping the nitrogen injection pipe (7) at the bottom connected to the support plate (2); S6; After the nitrogen injection pipe (7) is separated from the borehole, the borehole is backfilled.

2. The nitrogen injection method for fire prevention and extinguishing in the goaf during working face retreat according to claim 1, characterized in that: 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). The adjusting plate (9) has a through hole (91) that matches the nitrogen injection pipe (7). Bolts (92) for locking and positioning the nitrogen injection pipe (7) are threaded on both sides of the adjusting plate (9).

3. The nitrogen injection method for fire prevention and extinguishing in the goaf during working face retreat according to claim 1, characterized in that: Each nitrogen injection pipe (7) is connected to a flow regulating valve.

4. The nitrogen injection method for fire prevention and extinguishing in the goaf during working face retreat according to claim 1, characterized in that: 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 along the intake airway (11) to the goaf (4). The bundled tube (101) is a multi-section detachable structure.

5. The nitrogen injection method for fire prevention and extinguishing in the goaf during working face retreat according to claim 1, characterized in that: The dimensions of the support plate (2) are adapted to the space between two adjacent hydraulic supports (3).

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