A goaf fire prevention system and a goaf fire prevention method

Abstract

The application provides a goaf fire prevention system and a goaf fire prevention method. The goaf fire prevention system comprises a casing expansion assembly, a liquid supply assembly and a nitrogen injection assembly. At least a part of the casing expansion assembly is inserted into a borehole in a side wall and / or a top wall of a goaf. The borehole has a first region, a second region and a third region arranged at intervals in an axial direction. The casing expansion assembly is provided with a first hole, a second hole and a third hole at the first region, the second region and the third region, respectively. The nitrogen injection assembly is in communication with at least a part of the casing expansion assembly. The liquid supply assembly is in communication with at least a part of the casing expansion assembly. Through the technical scheme provided by the application, the problem that the nitrogen injection amount is large, nitrogen is wasted seriously and fire prevention work cannot be performed at specific positions in the fire prevention method of the N00 method in the prior art can be solved.

Description

Technical Field

[0001] This invention relates to the field of coal mine fire prevention technology, and more specifically, to a fire prevention system and method for goaf areas. Background Technology

[0002] In the field of coal mining technology, the existing N00 method (the name N00 mainly consists of a mining mode with "N" working faces in the mining panel, "0" roadways excavated in advance, and "0" coal pillars left) is based on the theory of roof-cutting short-arm beams. It uses constant-resistance, large-deformation anchor cables to provide advance support for the roadway roof, combined with directional pre-splitting blasting technology to cut the roof cantilever beams along the mining direction, causing the roof to collapse at a predetermined position, forming a gangue filling body to support the roadway. This technology cleverly utilizes mine pressure, converting the roof collapse pressure in the goaf into roadway support force, without the need for additional mining roadways or coal pillars.

[0003] Currently, the N00 method for self-forming roadways without coal pillars adopts a Z-type ventilation method, which has advantages such as stable airflow. Furthermore, under the Z-type ventilation method, the airflow can pass through the goaf, carrying away the gas within the goaf and reducing the amount of gas flowing from the goaf to the working face, thus helping to lower the gas concentration at the working face. However, the Z-type ventilation method leads to increased ventilation energy consumption, especially under conditions of poor goaf sealing, where air leakage is prone to occur when the airflow passes through the goaf, not only reducing ventilation efficiency but also potentially causing problems such as spontaneous combustion of coal in the goaf. Currently, the main method for fire prevention in the goaf of this coal mining face is to lay nitrogen injection pipelines in the intake airway. Nitrogen injection begins when the pipe opening is buried at the junction of the oxidation zone and the cooling zone, while simultaneously stopping the previous pipeline injection and re-burying a new pipeline, repeating this cycle until the working face is completely mined. However, when residual coal behind the oxidation zone in the goaf spontaneously combusts due to air leakage, there is nothing that can be done. This is because most of the injected nitrogen will diffuse towards the coal face due to the air leakage in the goaf, thus having little impact on the spontaneously combusting residual coal in the opposite direction, making it impossible to effectively prevent and extinguish the fire. At the same time, the nitrogen injection pipeline currently used only has one nitrogen injection port, which is located on the side of the intake airway. This layout makes the amount of nitrogen used for each nitrogen injection operation extremely large. More importantly, the nitrogen injection process lacks targeting and exhibits a "blind" characteristic, making it difficult to achieve precise nitrogen injection into dangerous areas.

[0004] Therefore, existing fire prevention methods for goaf areas suffer from problems such as large nitrogen injection volumes, significant nitrogen waste, and inability to conduct fire prevention operations at specific locations, which urgently need to be addressed. Summary of the Invention

[0005] This invention provides a goaf fire prevention system and method to at least solve the problems of large nitrogen injection volume, serious nitrogen waste, and inability to carry out fire prevention operations at specific locations in the existing N00 method fire prevention technology.

[0006] To address the aforementioned problems, according to one aspect of the present invention, a goaf fire prevention system is provided. This system is used for fire prevention operations in the goaf during coal mining. The underground roadway includes a panel main roadway, a return air main roadway, and a longwall face. The return air main roadway is connected to the panel main roadway to facilitate airflow. The goaf is located at the longwall face. During coal mining, the airflow enters the goaf along the return air main roadway and exits from the panel main roadway. The goaf fire prevention system includes a casing expansion assembly, a liquid supply assembly, and a nitrogen injection assembly. At least a portion of the casing expansion assembly is inserted into a borehole on the sidewall and / or topwall of the goaf. There are at least two boreholes and at least two casing expansion assemblies, which are horizontally spaced within the goaf, with each of the at least two casing expansion assemblies corresponding to one of the at least two boreholes. Each borehole has a first region, a second region, and a third region spaced apart along the axial direction, and the casing expansion assembly has a first hole corresponding to each of the first, second, and third regions. The system includes a first, second, and third borehole, each of which is configurably connected to the interior of the borehole. A casing expansion assembly is used to detect changes in oxygen and temperature at corresponding locations within the borehole. A nitrogen injection assembly is connected to at least a portion of the casing expansion assembly and is used to inject nitrogen into at least a portion of the casing expansion assembly to perform fire prevention and extinguishing operations at corresponding locations within the borehole. A liquid supply assembly is connected to at least a portion of the casing expansion assembly and is used to drive at least a portion of the casing expansion assembly to expand, thereby blocking at least one of the first, second, and third boreholes. This expanded portion is used to isolate the blocked borehole from the interior of the borehole, allowing the first, second, and third regions to be selectively connected to or disconnected from the interior of the casing expansion assembly. When the casing expansion assembly detects abnormal changes in oxygen or temperature in the second region, it drives the expansion portion to block the first and third boreholes, and the nitrogen injection assembly injects nitrogen into the second region through the second borehole.

[0007] Furthermore, the casing expansion assembly includes a casing structure, an expansion structure, a connecting structure, and a gas delivery detection structure; the casing structure has a receiving cavity; the expansion structure and the connecting structure are connected, and at least a portion of the expansion structure, the connecting structure, and the gas delivery detection structure is disposed within the receiving cavity; the connecting structure is used to cover a portion of the gas delivery detection structure; a first hole, a second hole, and a third hole are respectively disposed on the casing structure; the expansion structure is used to expand during fire prevention operations; when the expansion structure is in the expanded state, the expanded portion of the expansion structure prevents the corresponding position of the casing structure from communicating with the borehole; the gas delivery detection structure is disposed on the expansion structure and is used to detect changes in gas temperature and oxygen in the first region, the second region, and the third region, respectively; the gas delivery detection structure is connected to a nitrogen injection assembly to deliver nitrogen when fire prevention is required.

[0008] Furthermore, the expansion structure includes a single-layer expansion section and at least two double-layer expansion sections, both of which are disposed within the receiving cavity and correspond one-to-one with the first, second, and third holes, respectively. The single-layer expansion section, the connecting structure, and the double-layer expansion sections are sequentially connected along the axial direction of the casing structure, with adjacent double-layer expansion sections connected by a connecting structure. The single-layer expansion section is located inside the end of the casing structure facing the borehole. During fire prevention operations, the single-layer and double-layer expansion sections expand respectively, blocking the corresponding holes so that the casing structure at the corresponding position is not connected to the borehole. The expansion structure also includes at least five injection channels and at least two bundled tube channels. The injection channels are used to communicate with the liquid supply assembly to allow liquid flow. The bundled tube channels are used to connect wires and pipelines, with the wires electrically connected to the gas transmission detection structure and the pipelines connected to the nitrogen injection assembly and the gas transmission detection structure, respectively. Each single-layer expansion section has one injection channel and one bundled tube channel correspondingly disposed inside. A double-layer expansion section has two injection channels and one bundled tube channel inside, with at least five injection channels and at least two bundled tube channels not connected to each other; a single-layer expansion section is the first stage, a double-layer expansion section close to the first stage is the second stage, and a double-layer expansion section close to the second stage is the third stage, with the first, second, and third stages corresponding one-to-one with the first, second, and third regions, respectively; the first stage has one injection channel corresponding to the single-layer expansion section, the second stage has one injection channel corresponding to the single-layer expansion section, two injection channels corresponding to the double-layer expansion section, and one bundled tube channel corresponding to the single-layer expansion section, and the third stage has one injection channel corresponding to the single-layer expansion section, four injection channels corresponding to the double-layer expansion section, one bundled tube channel corresponding to the single-layer expansion section, and one bundled tube channel corresponding to the double-layer expansion section; there are at least three gas transmission detection structures, with at least three gas transmission detection structures corresponding one-to-one with one single-layer expansion section and at least two double-layer expansion sections.

[0009] Furthermore, the single-layer expansion section includes a single-layer expansion capsule; the two ends of the single-layer expansion capsule are made of rigid materials for connection with other components, and the middle part of the single-layer expansion capsule is made of elastic material for expansion by liquid injection through the liquid supply assembly; a first mounting groove is provided on the side wall of one end of the single-layer expansion capsule, the first mounting groove being used to install at least a part of the corresponding gas transmission detection structure; a liquid injection channel is provided on the end face of the single-layer expansion capsule near the first mounting groove, the liquid injection channel being used to connect the interior of the single-layer expansion capsule with the liquid supply assembly.

[0010] Furthermore, the double-layer expansion section includes an outer expansion capsule, an inner expansion capsule, a connecting tube, and a first support member; both ends of the outer and inner expansion capsules are made of rigid materials for connection with other components, while the middle portions of both are made of elastic materials for expansion through liquid injection via a liquid supply assembly; the outer expansion capsule covers the outer periphery of the inner expansion capsule; the first support member is disposed between the outer and inner expansion capsules; there are at least two first support members, each spaced circumferentially along the outer wall of the inner expansion capsule, and the first support member is used to support the outer expansion capsule; a second mounting groove is provided on the side wall of one end of the outer expansion capsule, and the second mounting groove is used for mounting... The device includes at least a portion of the corresponding gas delivery detection structure; the inner expansion capsule has at least three injection channels and at least one bundled tube channel on its end face near the second mounting groove, wherein, among the at least three injection channels, one injection channel is used to connect the single-layer expansion capsule to the liquid supply assembly, one injection channel is used to connect the outer expansion capsule to the liquid supply assembly, and one injection channel is used to connect the inner expansion capsule to the liquid supply assembly; the bundled tube channel is used to connect the gas delivery detection structure of the previous stage to the nitrogen injection assembly; a connecting tube is provided on the inner expansion capsule, one end of the connecting tube is connected to the injection channel, and the other end of the connecting tube is connected to the outer expansion capsule, and the connecting tube is used to connect the outer expansion capsule to the liquid supply assembly.

[0011] Furthermore, the casing structure also includes a casing body and a mesh tube disposed on the casing body; there are at least three mesh tubes, which are spaced apart along the axial direction of the casing body; the first hole, the second hole, and the third hole are respectively disposed on one mesh tube; a receiving cavity is formed inside the casing body, and the receiving cavity is connected to the borehole through the mesh tube; the at least three mesh tubes correspond one-to-one with the first region, the second region, and the third region, and the gas in the borehole enters the receiving cavity through the mesh tube, so that the corresponding gas transmission detection structure can detect changes in gas temperature and oxygen.

[0012] Furthermore, the connecting structure includes a connecting pipe body; the expansion structure includes a single-layer expansion part and at least two double-layer expansion parts; the single-layer expansion part, the connecting pipe body, and the double-layer expansion parts are connected sequentially along the axial direction of the casing structure, and two adjacent double-layer expansion parts are connected through a connecting pipe body; a pipeline groove extending along the axial direction is provided on the side wall of the connecting pipe body, the pipeline groove is used to allow the pipeline connected to the liquid injection channel, the wire electrically connected to the gas transmission detection structure, and the pipeline connected to the nitrogen injection assembly and the gas transmission detection structure to enter the interior of the connecting pipe body.

[0013] Furthermore, the gas delivery detection structure includes a sensor, a second support member, a gas delivery pipe, and a wire; the sensor is disposed inside the gas delivery pipe, and the second support member is disposed between the sensor and the gas delivery pipe. There are at least two second support members, which are spaced apart along the circumferential direction of the outer wall of the sensor. The sensor detects the gas temperature near the corresponding area inside the borehole. The sensor is electrically connected to the wire, which is disposed inside the gas delivery pipe and connected to an electrical wire to transmit current. The gas delivery pipe is connected to the nitrogen injection assembly to deliver nitrogen gas.

[0014] According to another aspect of the present invention, a method for fire prevention in goaf areas is provided, which is applied to the aforementioned goaf fire prevention system. The method includes a layout step; a fourth region is further provided within the borehole, and the first, second, third, and fourth regions are spaced apart along the axial direction of the borehole; the casing expansion assembly includes a casing structure, an expansion structure, a connecting structure, and a gas transmission detection structure; the casing structure includes four mesh tubes spaced apart along its axial direction; the expansion structure includes a single-layer expansion section and three double-layer expansion sections, with each single-layer expansion section and three double-layer expansion sections paired with one of the four mesh tubes. There are four gas transmission detection structures, each corresponding to one single-layer expansion section and three double-layer expansion sections. These sections are arranged sequentially and at intervals along the axial direction within the casing structure. The single-layer expansion section is the first stage, the double-layer expansion section closest to the first stage is the second stage, the double-layer expansion section closest to the second stage is the third stage, and the double-layer expansion section closest to the third stage is the fourth stage. The first, second, third, and fourth stages correspond one-to-one with the first, second, third, and fourth regions, respectively. The deployment steps include: along the advancing direction of the longwall face, using... The casing drilling device drills a first borehole with a diameter of 100 mm in the return air duct, perpendicular to the return air duct direction, and places the casing expansion assembly inside the first borehole. Specifically, when the initial caving step distance of the goaf is greater than or equal to 50 meters, the first borehole is located 30 meters from the panel main duct; when the initial caving step distance of the goaf is greater than or equal to 40 meters but less than 50 meters, the first borehole is located 20 meters from the panel main duct. After the casing expansion assembly is installed, one single-layer expansion section and three double-layer expansion sections are connected to the liquid supply assembly, and four gas transmission detection structures are connected to the nitrogen injection assembly. As coal mining operations continue and the overburden in the goaf collapses, during the third collapse, a second borehole is constructed at a predetermined distance from the first casing expansion assembly along the advancing direction of the longwall face. The second casing expansion assembly is then placed inside the second borehole. The single-layer expansion section, three double-layer expansion sections, and four mesh pipes within the casing expansion assembly in the second borehole must be staggered from the single-layer expansion section, three double-layer expansion sections, and four mesh pipes within the casing expansion assembly in the first borehole. The casing expansion assemblies are sequentially deployed according to the advancing progress of the longwall face until the longwall face is fully mined.

[0015] Furthermore, the goaf fire prevention method also includes fire prevention steps; the goaf also has a third borehole; the fire prevention steps include: when an abnormal change in oxygen or temperature occurs in the third region of the second borehole, air is pumped into the first and third boreholes, and the liquid supply assembly is controlled to inject liquid into the first and fourth stages of the first and third boreholes. The expansion part of the casing expansion assembly seals the mesh tube at the corresponding position, so that the first and fourth regions of the first and third boreholes are not connected to the internal casing structure of their boreholes. Under negative pressure, the area located in the first and third boreholes... The mesh pipes at the second and third stages affect the airflow leakage in the second borehole through negative pressure extraction. Simultaneously, the liquid supply assembly is controlled to inject liquid into the first, second, and fourth stages of the second borehole to seal the mesh pipes in the first, second, and fourth areas respectively. Then, the nitrogen injection assembly is controlled to inject nitrogen into the gas transmission detection structure corresponding to the third stage in the second borehole to extinguish the fire in the third area of ​​the second borehole where anomalies have occurred. After the nitrogen injection is completed, the pressure of the expanded structure is released, and the gas transmission detection structure is used to detect changes in oxygen and gas temperature near the mesh pipes.

[0016] The present invention provides a goaf fire prevention system for coal mining operations. The system includes an underground roadway comprising a panel main roadway, a return air main roadway, and a longwall face. The return air main roadway connects to the panel main roadway to facilitate airflow. The goaf is located at the longwall face. During coal mining, airflow enters the goaf along the return air main roadway and exits from the panel main roadway. The goaf fire prevention system includes a casing expansion assembly, a liquid supply assembly, and a nitrogen injection assembly. At least a portion of the casing expansion assembly is inserted into boreholes on the sidewall and / or topwall of the goaf. There are at least two boreholes and at least two casing expansion assemblies, which are horizontally spaced within the goaf, with each of the at least two casing expansion assemblies corresponding to one of the at least two boreholes. Each borehole has a first region, a second region, and a third region spaced apart along the axial direction. The casing expansion assemblies are respectively provided with first holes, second holes, and third holes in the first, second, and third regions. The third hole, the first hole, the second hole, and the third hole are respectively connected to the interior of the borehole in a way that allows for both open and closed communication. The casing expansion assembly is used to detect changes in oxygen and temperature at corresponding locations within the borehole. The nitrogen injection assembly is connected to at least a portion of the casing expansion assembly and is used to inject nitrogen into at least a portion of the casing expansion assembly to perform fire prevention and extinguishing operations at corresponding locations within the borehole. The liquid supply assembly is connected to at least a portion of the casing expansion assembly and is used to drive at least a portion of the casing expansion assembly to expand, thereby driving the expanded portion to block at least one of the first hole, the second hole, and the third hole. This expanded portion is used to isolate the blocked hole from the interior of the borehole, so that the first region, the second region, and the third region can be selectively connected to or disconnected from the interior of the casing expansion assembly. When the casing expansion assembly detects abnormal changes in oxygen or temperature in the second region, it drives the expanded portion to block the first hole and the third hole, and the nitrogen injection assembly injects nitrogen into the second region through the second hole.

[0017] By setting a first hole, a second hole, and a third hole along the axial direction on the casing expansion assembly, and making the first hole, the second hole, and the third hole correspond one-to-one with the first region, the second region, and the third region respectively, the local expansion of the casing expansion assembly can achieve the opening and closing of the airflow channels in different regions. When an abnormal oxygen concentration or an upward trend in temperature is detected in the second region, the casing expansion assembly partially expands to close the first hole and the third hole, and the nitrogen injection assembly injects nitrogen into the target region through the second hole, thereby improving the concentration and efficiency of the gas action. This invention avoids the problems of low nitrogen utilization and uneven coverage caused by airflow diffusion in traditional single nitrogen injection ports, enabling nitrogen to act more precisely on potential spontaneous combustion sources and reducing unnecessary gas consumption. The expansion part of the casing expansion assembly remains in a contracted state when not in operation, without completely blocking the natural gas exchange between the borehole and the goaf, facilitating continuous monitoring of environmental parameters. This invention has a simple structure, low cost, high reliability, and is easy to assemble and maintain. It solves the problems of large nitrogen injection volume, serious nitrogen waste, and inability to perform fire prevention operations on specific locations in the existing N00 method of fire prevention technology, making it suitable for large-scale promotion and use. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 A partial layout diagram of an underground tunnel provided by an embodiment of the present invention is shown from a top view.

[0020] Figure 2 A partial structural schematic diagram of the fire prevention system for goaf areas provided in an embodiment of the present invention is shown;

[0021] Figure 3 A partial structural schematic diagram of the sleeve expansion assembly at the first stage provided in an embodiment of the present invention is shown.

[0022] Figure 4 A partial structural schematic diagram of the sleeve expansion assembly at the second stage provided in an embodiment of the present invention is shown;

[0023] Figure 5 A partial structural schematic diagram of the double-layer expansion section of the sleeve expansion assembly provided in an embodiment of the present invention is shown;

[0024] Figure 6 A partial structural schematic diagram of the mesh tube of the sleeve expansion assembly provided in an embodiment of the present invention is shown;

[0025] Figure 7 A partial structural schematic diagram of the connection structure of the sleeve expansion assembly provided in an embodiment of the present invention is shown.

[0026] Figure 8 A schematic diagram of the internal structure of the gas delivery detection structure of the casing expansion assembly provided in an embodiment of the present invention is shown.

[0027] Figure 9 A schematic diagram of the external structure of the gas delivery detection structure of the casing expansion assembly provided in an embodiment of the present invention is shown.

[0028] Figure 10 A partial structural schematic diagram of the first to third holes of the sleeve expansion assembly provided in an embodiment of the present invention is shown.

[0029] The above figures include the following reference numerals:

[0030] 10. Sleeve structure; 11. Sleeve body; 12. Receiving cavity; 13. Mesh tube; 14. First hole; 15. Second hole; 16. Third hole;

[0031] 20. Expansion structure; 21. Single-layer expansion section; 211. Single-layer expansion capsule; 212. First mounting groove; 22. Double-layer expansion section; 221. Outer expansion capsule; 222. Inner expansion capsule; 223. Second mounting groove; 224. Connecting pipe; 225. First support member; 23. Liquid injection channel; 24. Bundle tube channel;

[0032] 30. Connection structure; 31. Connecting pipe body; 311. Pipeline trench;

[0033] 40. Gas delivery detection structure; 41. Sensor; 42. Second support component; 43. Gas delivery pipe; 44. Wire. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] like Figures 1 to 10As shown, an embodiment of the present invention provides a goaf fire prevention system, which is used for fire prevention operations in the goaf during coal mining. The underground roadway includes a panel main roadway, a return air main roadway, and a longwall face. The return air main roadway is connected to the panel main roadway to facilitate airflow. The goaf is located at the longwall face. During coal mining, the airflow enters the goaf along the return air main roadway and then flows out from the panel main roadway. The goaf fire prevention system includes a casing expansion assembly, a liquid supply assembly, and a nitrogen injection assembly. At least a portion of the casing expansion assembly is inserted into boreholes on the sidewall and / or topwall of the goaf. There are at least two boreholes and at least two casing expansion assemblies, which are horizontally spaced within the goaf, with at least two casing expansion assemblies corresponding to at least two boreholes. Each borehole has a first region, a second region, and a third region spaced apart along the axial direction. The casing expansion assembly is respectively provided with a first hole 14, a second hole 15, and a third hole 16 in the first, second, and third regions, respectively. Hole 14, second hole 15, and third hole 16 are respectively connected to the interior of the borehole in a way that allows for both open and closed communication. A casing expansion assembly is used to detect changes in oxygen and temperature at corresponding locations within the borehole. A nitrogen injection assembly is connected to at least a portion of the casing expansion assembly and is used to inject nitrogen into at least a portion of the casing expansion assembly to perform fire prevention and extinguishing operations at corresponding locations within the borehole. A liquid supply assembly is connected to at least a portion of the casing expansion assembly and is used to drive at least a portion of the casing expansion assembly to expand, thereby blocking at least one of the first hole 14, second hole 15, and third hole 16. This expanded portion is used to isolate the blocked hole from the interior of the borehole, allowing the first, second, and third regions to be selectively connected to or disconnected from the interior of the casing expansion assembly. When the casing expansion assembly detects abnormal changes in oxygen or temperature in the second region, it drives the expansion portion to block the first hole 14 and third hole 16, and the nitrogen injection assembly injects nitrogen into the second region through the second hole 15.

[0036] By axially configuring a first hole 14, a second hole 15, and a third hole 16 on the casing expansion assembly, and ensuring that the first hole 14, the second hole 15, and the third hole 16 are connected to the first region, the second region, and the third region respectively, the local expansion of the casing expansion assembly can achieve the opening and closing of the airflow channels in different regions. When an abnormal oxygen concentration or an increasing temperature trend is detected in the second region, the casing expansion assembly partially expands to close the first hole 14 and the third hole 16, and the nitrogen injection assembly injects nitrogen into the target region through the second hole 15, thereby improving the concentration and efficiency of the gas action. This invention avoids the problems of low nitrogen utilization and uneven coverage caused by airflow diffusion in traditional single nitrogen injection ports, enabling nitrogen to act more precisely on potential spontaneous combustion sources and reducing unnecessary gas consumption. The expansion part of the casing expansion assembly remains in a contracted state when not in operation, without completely blocking the natural gas exchange between the borehole and the goaf, facilitating continuous monitoring of environmental parameters. This invention has a simple structure, low cost, high reliability, and is easy to assemble and maintain. It solves the problems of large nitrogen injection volume, serious nitrogen waste, and inability to perform fire prevention operations on specific locations in the existing N00 method of fire prevention technology, making it suitable for large-scale promotion and use.

[0037] like Figure 1 and Figure 10 As shown, the casing expansion assembly includes a casing structure 10, an expansion structure 20, a connecting structure 30, and a gas delivery detection structure 40. The casing structure 10 has a receiving cavity 12. The expansion structure 20 and the connecting structure 30 are connected, and at least a portion of the expansion structure 20, the connecting structure 30, and the gas delivery detection structure 40 is disposed within the receiving cavity 12. The connecting structure 30 is used to cover a portion of the gas delivery detection structure 40. A first hole 14, a second hole 15, and a third hole 16 are respectively disposed on the casing structure 10. The expansion structure 20 is used to expand during fire prevention operations. When the expansion structure 20 is in the expanded state, the expanded portion of the expansion structure 20 prevents the corresponding position of the casing structure 10 from communicating with the borehole. The gas delivery detection structure 40 is disposed on the expansion structure 20 and is used to detect changes in gas temperature and oxygen in the first, second, and third regions, respectively. The gas delivery detection structure 40 is connected to a nitrogen injection assembly to deliver nitrogen when fire prevention is required.

[0038] By placing the sleeve structure 10, expansion structure 20, connecting structure 30, and gas delivery detection structure 40 inside the sleeve expansion assembly, the gas delivery detection structure 40 is directly installed in the adjacent area of ​​the expansion structure 20, shortening the spatial distance between the sensing element and the target monitoring area, and improving the real-time performance and accuracy of temperature and oxygen concentration data acquisition. The receiving cavity 12 inside the sleeve structure 10 provides a stable installation space for each component, enabling the expansion structure 20 to effectively block at least one of the first hole 14, the second hole 15, and the third hole 16 during controlled expansion. The system effectively blocks airflow channels in different areas within the borehole. The connecting structure 30 enhances the overall rigidity and compressive strength of the structure, reducing interference from external rock deformation or debris impacts on pipelines and lines. The direct connection between the gas transmission detection structure 40 and the nitrogen injection component allows nitrogen to be directly delivered to the target area upon detection of an abnormal signal. This enhances the system's stability and reliability in complex goaf environments and provides reliable structural support for subsequent multi-level linkage control, facilitating real-time monitoring and timely intervention of goaf areas during coal mining.

[0039] like Figures 1 to 10As shown, the expansion structure 20 includes a single-layer expansion section 21 and at least two double-layer expansion sections 22. The single-layer expansion section 21 and at least two double-layer expansion sections 22 are all disposed within the receiving cavity 12 and correspond one-to-one with the first hole 14, the second hole 15, and the third hole 16, respectively. The single-layer expansion section 21, the connecting structure 30, and the double-layer expansion sections 22 are sequentially connected along the axial direction of the casing structure 10. Adjacent double-layer expansion sections 22 are connected by a connecting structure 30. The single-layer expansion section 21 is located within the end of the casing structure 10 facing the borehole. The single-layer expansion section 21 and... The double-layer expansion section 22 expands during fire prevention operations, blocking the corresponding holes to prevent the sleeve structure 10 at the corresponding position from communicating with the borehole. The expansion structure 20 also includes at least five injection channels 23 and at least two bundled tube channels 24. The injection channels 23 are used to communicate with the liquid supply assembly to allow liquid to flow. The bundled tube channels 24 are used to transmit wires and pipelines. The wires are electrically connected to the gas transmission detection structure 40, and the pipelines are respectively connected to the nitrogen injection assembly and the gas transmission detection structure 40. A single-layer expansion section 21 has one injection channel 23 and one bundled tube channel 24 correspondingly arranged inside. Each double-layer expansion section 22 has two injection channels 23 and one bundled tube channel 24 respectively, and at least five injection channels 23 and at least two bundled tube channels 24 are not interconnected. A single-layer expansion section 21 is the first level, the double-layer expansion section 22 closest to the first level is the second level, and the double-layer expansion section 22 closest to the second level is the third level. The first, second, and third levels correspond one-to-one with the first, second, and third regions, respectively. The first level has one injection channel 23 corresponding to the single-layer expansion section 21, and the second level has one corresponding injection channel 23 connected to the single-layer expansion section 21. The third stage includes one injection channel 23 corresponding to the single-layer expansion section 21, four injection channels 23 corresponding to the double-layer expansion section 22, one bundled tube channel 24 corresponding to the single-layer expansion section 21, and one bundled tube channel 24 corresponding to the single-layer expansion section 21. There are at least three gas delivery detection structures 40, and each of the at least three gas delivery detection structures 40 is arranged in a one-to-one correspondence with one single-layer expansion section 21 and at least two double-layer expansion sections 22.

[0040] By setting a single-layer expansion section 21 and at least two double-layer expansion sections 22 to form a graded expansion structure 20, corresponding to the first hole 14, the second hole 15, and the third hole 16 respectively, independent and controllable sealing of different areas within the borehole is achieved, enhancing the system's response accuracy. The single-layer expansion section 21 and the double-layer expansion section 22 expand under the drive of the liquid supply assembly, improving the sealing performance and pressure resistance of the sealing area. The liquid injection channel 23 and the bundle tube channel 24 are independently arranged within each level and are not interconnected, ensuring independent control of the first to third levels by the liquid supply assembly and avoiding cross-flow of liquid or gas between channels. The system's reliability is improved by mitigating malfunctions. The second and third stage double-layer expansion sections 22 are each equipped with multiple injection channels 23, supporting separate injection of liquid into the inner and outer capsules, ensuring a gradual and controllable sealing process. The independent design of the bundled tube channels 24 ensures that the sensing lines of the gas transmission detection structure 40 and the nitrogen delivery pipeline are not squeezed or entangled in complex downhole environments, improving signal transmission stability and long-term operational safety. Multiple gas transmission detection structures 40 correspond one-to-one with each stage of expansion structures, enhancing the system's adaptability and synergistic capabilities in addressing the risk of spontaneous combustion at different depths in the goaf.

[0041] like Figure 3 As shown, the single-layer expansion section 21 includes a single-layer expansion capsule 211; the two ends of the single-layer expansion capsule 211 are made of rigid materials for connection with other components, and the middle part of the single-layer expansion capsule 211 is made of elastic material for expansion by liquid injection through the liquid supply assembly; a first mounting groove 212 is provided on the side wall of one end of the single-layer expansion capsule 211, the first mounting groove 212 is used to install at least a part of the corresponding gas transmission detection structure 40; a liquid injection channel 23 is provided on the end face of the single-layer expansion capsule 211 near the first mounting groove 212, the liquid injection channel 23 is used to connect the interior of the single-layer expansion capsule 211 with the liquid supply assembly.

[0042] By employing a single-layer expansion capsule 211 structure with rigid materials at both ends and an elastic material in the middle within the single-layer expansion section 21, it can expand uniformly along the axial direction when driven by the fluid supply assembly. This seals the first hole 14, preventing the first region from communicating with the receiving cavity 12. Simultaneously, the rigid structure at both ends provides a stable connection reference for the device, facilitating axial assembly with the connecting structure 30 and the casing structure 10, thus improving the structural integrity of the overall assembly under complex downhole stress environments. The first mounting groove 212 is located on the sidewall of the single-layer expansion capsule 211 near the injection channel 23, allowing... The gas transmission detection structure 40 can be deployed close to the expansion area to directly detect the gas temperature and oxygen concentration in the first area of ​​the goaf, avoiding response delays caused by external sensors or excessive distance, and improving the sensitivity of abnormal signal capture. The liquid injection channel 23 is directly opened on the end face of the single-layer expansion capsule 211, which is conducive to achieving rapid and uniform expansion response and reducing the sealing delay caused by liquid delivery lag. The single-layer expansion capsule 211 maintains a contracted shape when not in operation, without obstructing the natural flow of air in the goaf, thus improving the accuracy and timeliness of the gas transmission detection structure 40.

[0043] like Figure 4 and Figure 5As shown, the double-layer expansion section 22 includes an outer expansion capsule 221, an inner expansion capsule 222, a connecting tube 224, and a first support member 225. Both ends of the outer and inner expansion capsules 221 and 222 are made of rigid materials for connection with other components, while the middle portions of both are made of elastic materials for expansion via a liquid supply assembly. The outer expansion capsule 221 covers the outer periphery of the inner expansion capsule 222. The first support member 225 is disposed between the outer and inner expansion capsules 221 and 222. At least two first support members 225 are provided, each spaced circumferentially along the outer wall of the inner expansion capsule 222, and are used to support the outer expansion capsule 221. A second mounting groove 223 is provided on the side wall of one end of the outer expansion capsule 221. 3. At least a portion of the corresponding gas delivery detection structure 40 is installed; at least three liquid injection channels 23 and at least one bundled tube channel 24 are provided on the end face of the inner expansion capsule 222 near the second mounting groove 223, wherein, among the at least three liquid injection channels 23, one liquid injection channel 23 is used to connect the single-layer expansion capsule 211 to the liquid supply assembly, one liquid injection channel 23 is used to connect the outer expansion capsule 221 to the liquid supply assembly, and one liquid injection channel 23 is used to connect the inner expansion capsule 222 to the liquid supply assembly; the bundled tube channel 24 is used to connect the previous stage gas delivery detection structure 40 to the nitrogen injection assembly; the connecting pipe 224 is provided on the inner expansion capsule 222, one end of the connecting pipe 224 is connected to the liquid injection channel 23, and the other end of the connecting pipe 224 is connected to the outer expansion capsule 221, and the connecting pipe 224 is used to connect the outer expansion capsule 221 to the liquid supply assembly.

[0044] By providing a composite structure of an outer expansion capsule 221 and an inner expansion capsule 222 in the double-layer expansion section 22, and arranging at least two circumferentially spaced first support members 225 between them, the outer expansion capsule 221 can expand radially and uniformly during liquid injection, enhancing its fit with the inner wall of the sleeve structure 10, thereby effectively sealing the second hole 15 or the third hole 16 and improving the sealing reliability of the plugging; the inner expansion capsule 222 can provide support for the outer expansion capsule 221; the second mounting groove 223 is provided on the side wall of the outer expansion capsule 221, allowing the gas delivery detection structure 40 to be tightly fitted. The expansion zone is designed to enable timely detection of gas temperature and oxygen concentration in the target area. The inner expansion capsule 222 integrates at least three independent injection channels 23 on its end face, which are used to control the liquid supply of the inner expansion capsule 222, the outer expansion capsule 221, and the front single-layer expansion section 21, respectively, so that the liquid supply assembly can independently control each component. The bundle tube channel 24 not only provides an independent channel for the sensing line and nitrogen injection pipeline of the front-stage gas transmission detection structure 40, but also ensures that the signals and fluids of each functional module do not interfere with each other in multi-stage linkage operations, thereby improving the operational stability of the system in complex downhole environments.

[0045] In a specific embodiment of the present invention, the total length of the outer expansion capsule 221 of the double-layer expansion part 22 is 1200mm, of which the length of the expansion part is 900mm, and the outer expansion capsule 221 can completely block the mesh tube 13 after being injected with liquid and expanded, so that the gas in the borehole cannot enter the receiving cavity 12.

[0046] like Figure 1 and Figure 10 As shown, the casing structure 10 also includes a casing body 11 and a mesh tube 13 disposed on the casing body 11; there are at least three mesh tubes 13, which are spaced apart along the axial direction of the casing body 11; the first hole 14, the second hole 15 and the third hole 16 are respectively disposed on one mesh tube 13; a receiving cavity 12 is formed inside the casing body 11, and the receiving cavity 12 is connected to the borehole through the mesh tube 13; the at least three mesh tubes 13 correspond one-to-one with the first region, the second region and the third region, and the gas in the borehole enters the receiving cavity 12 through the mesh tube 13 so that the corresponding gas delivery detection structure 40 can detect changes in gas temperature and oxygen.

[0047] By axially spacing at least three mesh tubes 13 on the casing body 11, and with the first hole 14, the second hole 15, and the third hole 16 respectively positioned on each mesh tube 13, a multi-level, zoned airflow channel is constructed. This allows gas from the first, second, and third regions of the goaf to enter the containment cavity 12 inside the casing through the corresponding mesh tubes 13, providing gas samples from the corresponding regions to the gas transmission detection structure 40, thus improving the timeliness and accuracy of temperature and oxygen concentration detection. The porous structure of the mesh tubes 13 allows for free gas permeation while effectively preventing large rock fragments from entering the containment cavity 12, reducing the risk of internal structural damage and extending the long-term stability of the system. The casing body 11, as the main load-bearing structure, provides stable support for the internal components.

[0048] like Figure 1 and Figure 7 As shown, the connecting structure 30 includes a connecting pipe body 31; the expansion structure 20 includes a single-layer expansion part 21 and at least two double-layer expansion parts 22; the single-layer expansion part 21, the connecting pipe body 31, and the double-layer expansion parts 22 are connected sequentially along the axial direction of the sleeve structure 10, and two adjacent double-layer expansion parts 22 are connected through a connecting pipe body 31; a pipeline groove 311 is provided on the side wall of the connecting pipe body 31, which is axially penetrating, and the pipeline groove 311 is used to allow the pipeline connected to the liquid injection channel 23, the wire electrically connected to the gas transmission detection structure 40, and the pipeline connected to the nitrogen injection assembly and the gas transmission detection structure 40 to enter the interior of the connecting pipe body 31.

[0049] By employing a connecting pipe body 31 with an axially penetrating pipeline groove 311 in the connecting structure 30, the high-pressure liquid pipeline connected to the injection channel 23, the wire 44 used in the gas transmission detection structure 40, and the gas transmission pipeline between the nitrogen injection assembly and the gas transmission detection structure 40 can be centrally arranged within the internal space of the connecting pipe body 31. This reduces the risk of multiple pipelines crossing, rubbing against each other, or being squeezed by rock mass within the borehole, and improves the stability of the electrical and fluid pathways of the system during long-term service. The open structure of the pipeline groove 311 extending axially facilitates the orderly insertion and fixing of each pipeline during the assembly stage, simplifying the downhole installation process and providing operational space for subsequent maintenance or replacement. As a connecting component, the connecting pipe body 31 not only undertakes the function of transmitting axial force but also provides a positioning reference for adjacent expansion sections, ensuring that the single-layer expansion section 21 and each double-layer expansion section 22 maintain a fixed axial distance within the borehole. This maintains the matching relationship between the first hole 14, the second hole 15, and the third hole 16 and the corresponding monitoring area of ​​the goaf, avoiding inaccurate monitoring or sealing failure due to assembly deviations.

[0050] like Figure 1 , Figure 8 and Figure 9 As shown, the gas delivery detection structure 40 includes a sensor 41, a second support member 42, a gas delivery pipe 43, and a wire 44. The sensor 41 is disposed inside the gas delivery pipe 43, and the second support member 42 is disposed between the sensor 41 and the gas delivery pipe 43. There are at least two second support members 42, which are spaced apart along the circumferential direction of the outer wall of the sensor 41. The sensor 41 detects the gas temperature near the corresponding area inside the borehole. The sensor 41 is electrically connected to the wire 44, which is disposed inside the gas delivery pipe 43 and connected to an electrical wire to transmit current. The gas delivery pipe 43 is connected to the nitrogen injection assembly to deliver nitrogen gas.

[0051] By embedding the sensor 41 inside the gas pipeline 43 and circumferentially spacing at least two second support members 42 on its outer wall, the sensor 41 can stably detect the gas temperature and oxygen in the first, second, or third region. The second support member 42 serves as a radial positioning structure, providing a uniform airflow channel for the sensor 41, improving response speed and data representativeness. The wire 44 passes through the inside of the gas pipeline 43, achieving a reliable connection with the wires of the external control system, reducing interference from the humid and dusty environment downhole on electrical signal transmission, and improving the stability and noise resistance of temperature and oxygen concentration data. The gas pipeline 43 also functions as a gas delivery system, allowing the nitrogen injection assembly to directly inject nitrogen into the target area through an independent channel when fire prevention operations are triggered, avoiding the waste and poor fire prevention effect caused by a single nitrogen injection pipeline.

[0052] This invention also provides a method for fire prevention in goaf areas, which is applied to the aforementioned goaf fire prevention system. The method includes a layout step; the borehole also has a fourth region, with the first, second, third, and fourth regions spaced apart along the borehole's axial direction; the casing expansion assembly includes a casing structure 10, an expansion structure 20, a connecting structure 30, and a gas transmission detection structure 40; the casing structure 10 includes four mesh tubes 13 spaced apart along its axial direction; the expansion structure 20 includes a single-layer expansion section 21 and three double-layer expansion sections 22, which are connected to the four mesh tubes 13. One-to-one correspondence; there are four gas transmission detection structures 40, each corresponding to one single-layer expansion section 21 and three double-layer expansion sections 22; the single-layer expansion section 21 and the three double-layer expansion sections 22 are arranged sequentially and at intervals along the axial direction within the casing structure 10, with the single-layer expansion section 21 being the first stage, the double-layer expansion section 22 closest to the first stage being the second stage, the double-layer expansion section 22 closest to the second stage being the third stage, and the double-layer expansion section 22 closest to the third stage being the fourth stage; the first, second, third, and fourth stages correspond one-to-one with the first, second, third, and fourth regions, respectively; the deployment steps include: along the mining section... In the direction of face advance, using a casing drilling device, a first borehole with a diameter of 100 mm is drilled in the return airway towards the goaf, perpendicular to the return airway direction, and the casing expansion assembly is placed in the first borehole. Specifically, when the initial caving step distance of the goaf is greater than or equal to 50 meters, the first borehole is set at a position 30 meters from the panel main roadway; when the initial caving step distance of the goaf is greater than or equal to 40 meters but less than 50 meters, the first borehole is set at a position 20 meters from the panel main roadway. After the casing expansion assembly is installed, one single-layer expansion section 21 and three double-layer expansion sections 22 are connected to the liquid supply assembly, and four gas transmission detection structures 40 are connected to the nitrogen injection assembly. As coal mining continues, the overlying strata of the goaf collapse. During the third collapse, a second borehole is constructed at a set distance from the first casing expansion assembly along the advancing direction of the longwall face. The second casing expansion assembly is placed inside the second borehole. The single-layer expansion section 21, three double-layer expansion sections 22, and four mesh pipes 13 within the casing expansion assembly in the second borehole must be staggered from the single-layer expansion section 21, three double-layer expansion sections 22, and four mesh pipes 13 within the casing expansion assembly in the first borehole. The casing expansion assemblies are sequentially deployed according to the advancing progress of the longwall face until the longwall face is fully mined.

[0053] The goaf fire prevention method involves vertically deploying multiple sets of casing expansion components in the return airway and combining this with the periodic collapse pattern of the overlying strata of the goaf roof to achieve layered and staggered monitoring and intervention in different depth areas, namely the first, second, third, and fourth zones. In each borehole, the casing structure 10 is equipped with four axially distributed mesh pipes 13, corresponding to one single-layer expansion section 21 and three double-layer expansion sections 22, respectively. The gas temperature and oxygen concentration of each level are independently collected by the gas transmission detection structure 40. When the goaf roof collapses for the third time, a second borehole is constructed at a set step distance from the first borehole, and the first to fourth levels of the second set of casing expansion components are connected to the first borehole. The staggered arrangement of the first to fourth levels within the borehole creates spatial complementarity between the detection and sealing areas of the two sets of casing expansion assemblies, effectively covering irregular fissures formed by collapse in the goaf and avoiding monitoring blind spots. Simultaneously, the starting position of the borehole is dynamically adjusted 30 or 20 meters from the main roadway of the panel based on the initial collapse step distance, allowing the casing expansion assemblies to better conform to the evolution trend from the oxidation zone to the cooling zone boundary in the goaf, enhancing the fire prevention intervention effect. Each casing expansion assembly completes pipeline connection with the liquid supply and nitrogen injection assemblies during the installation phase, laying the foundation for subsequent rapid response. This improves the continuity, coverage, and dynamic adaptability of the system during longwall mining, enhancing the reliability and repeatability of multi-stage, multi-level fire prevention operations within the goaf.

[0054] like Figure 1 and Figure 2 As shown, the goaf fire prevention method also includes fire prevention steps; there is also a third borehole in the goaf; the fire prevention steps include: when an abnormal change in oxygen or temperature occurs in the third region of the second borehole, air is pumped into the first and third boreholes, and the liquid supply assembly is controlled to inject liquid into the first and fourth stages of the first and third boreholes. The expansion part of the casing expansion assembly seals the corresponding mesh tube 13, so that the first and fourth regions of the first and third boreholes are not connected to the inside of the casing structure 10 in their boreholes. Under negative pressure, the second and fourth stages of the first and third boreholes are... The mesh tube 13 at the third stage affects the airflow leakage in the second borehole through negative pressure extraction; at the same time, the liquid supply component is controlled to inject liquid into the first, second and fourth stages of the second borehole to seal the mesh tube 13 in the first, second and fourth areas respectively. Then, the nitrogen injection component is controlled to inject nitrogen into the gas transmission detection structure 40 corresponding to the third stage in the second borehole to extinguish the fire in the third area of ​​the second borehole where anomalies have occurred; after the nitrogen injection is completed, the pressure of the expanded structure 20 is released, and the gas transmission detection structure 40 is used to detect the oxygen change and gas temperature near the mesh tube 13.

[0055] The goaf fire prevention method involves initiating multi-hole coordinated intervention when an abnormal oxygen concentration or rising temperature trend occurs in the third region of the second borehole. This involves utilizing the expansion structures 20 of the first and third boreholes to perform localized liquid injection expansion on their respective first and fourth stages, sealing the corresponding mesh pipes 13, thus disconnecting the first and fourth regions of the first and third boreholes from the internal containment cavity 12. Simultaneously, air is extracted from the second and third regions of the first and third boreholes. Under the negative pressure of this extraction, gas preferentially passes through the unsealed second and third stage mesh pipes 13 in the first and third boreholes, forming directional airflow channels. This interferes with the air leakage path in the abnormal region of the second borehole, inhibiting the continuous supply of oxygen to the high-temperature point. Simultaneously, liquid injection expansion is performed on the first, second, and fourth stages of the second borehole itself. The method involves sealing off gas channels outside the abnormal area to achieve isolation and blockage of the third stage, creating a favorable environment for precise nitrogen injection. Subsequently, nitrogen is injected into the gas transmission detection structure 40 corresponding to the third stage by controlling the nitrogen injection components, allowing nitrogen to accumulate efficiently in the confined area, reducing local oxygen concentration, inhibiting the coal oxidation reaction process, and improving gas utilization and fire extinguishing efficiency. After the nitrogen injection operation is completed, the expanded structure 20 is depressurized to restore the system to standby state. At the same time, the gas transmission detection structure 40 is used to re-measure the gas around the mesh pipe 13 to verify the fire extinguishing effect and provide data support for subsequent evaluation. This method relies on the spatial distribution and hierarchical control capability of multiple sets of casing expansion components to avoid the resource waste and ventilation interference caused by large-scale nitrogen injection of the entire goaf, and improves the targeting and economy of fire prevention operations.

[0056] The working process and principle of a specific embodiment of the present invention will now be described in detail as follows:

[0057] The goaf fire prevention system and method of the present invention, during the coal mine mining process, involves drilling multiple boreholes vertically along the return air roadway into the goaf, and installing casing expansion components in each borehole to achieve real-time monitoring and precise intervention of air leakage channels and spontaneous combustion hazard areas in the goaf. The core of the system consists of a casing structure 10, an expansion structure 20, a connecting structure 30, and a gas transmission detection structure 40. The casing structure 10 includes a casing body 11 and axially spaced mesh pipes 13, with multiple mesh pipes 13 corresponding to the first hole 14, second hole 15, third hole 16, and fourth hole, respectively connecting the first to fourth areas within the borehole. The expansion structure 20 consists of a single-layer expansion part 21 and a double-layer expansion part 22, which expands by injecting liquid through a liquid supply component, sealing the corresponding mesh pipes 13 and blocking the oxygen transmission path. The gas transmission detection structure 40 includes a sensor 41, a second support 42, a gas transmission pipe 43, and a wire 44, placed on the sidewall of each expansion part to detect the gas temperature and oxygen concentration in the corresponding area in real time. The connecting pipe 31 of the connecting structure 30 centrally houses the injection pipeline, electrical wires, and nitrogen injection pipeline to ensure system functional coordination. During operation, the system remains in a contracted state, allowing natural ventilation. When a borehole, such as the third area of ​​the second borehole, experiences an abnormal temperature rise or oxygen consumption, the system activates its fire prevention mode: First, it controls the expansion of the first and fourth stage expansion structures 20 of the adjacent first and third boreholes, sealing the corresponding mesh pipes 13, and controls the air extraction of the first and third boreholes, concentrating the negative pressure on the mesh pipes 13 corresponding to the second and third stages, thereby affecting the airflow leakage in the second borehole; simultaneously, it injects liquid to expand the first, second, and fourth stage expansion structures 20 of the second borehole, leaving only the third area of ​​the borehole connected to the casing expansion assembly inside the hole, and then controls the gas delivery detection structure 40 to inject nitrogen into the area to achieve directional fire suppression. After the operation is completed, the expansion structure 20 is depressurized, gas parameters are re-measured to confirm fire control, and monitoring continues.

[0058] In summary, this invention provides a goaf fire prevention system and method. The goaf fire prevention system uses a casing expansion assembly with a first hole 14, a second hole 15, and a third hole 16 arranged axially along the casing expansion assembly. The first hole 14, the second hole 15, and the third hole 16 are respectively connected to the first region, the second region, and the third region. This allows the local expansion of the casing expansion assembly to open and close the airflow channels in different regions. When an abnormal oxygen concentration or an increasing temperature trend is detected in the high-temperature hazard area behind the oxidation zone of the goaf corresponding to the second region, the casing expansion assembly partially expands to close the first hole 14 and the third hole 16, and the nitrogen injection assembly injects nitrogen into the target area through the second hole 15, thereby improving the concentration and efficiency of the gas action. This invention avoids the problems of low nitrogen utilization and uneven coverage caused by airflow diffusion in traditional single nitrogen injection ports, enabling nitrogen to act more precisely on potential spontaneous combustion sources and reducing unnecessary gas consumption. The expansion part of the casing expansion assembly remains in a contracted state when not in operation, without completely blocking the natural gas exchange between the borehole and the goaf, facilitating continuous monitoring of environmental parameters. This invention has a simple structure, low cost, high reliability, and is easy to assemble and maintain. It solves the problems of large nitrogen injection volume, serious nitrogen waste, and inability to perform fire prevention operations on specific locations in the existing N00 method of fire prevention technology, making it suitable for large-scale promotion and use.

[0059] The technical features of the embodiments described above can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered to be within the scope of this specification.

[0060] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0061] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0062] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0063] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0064] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fire prevention system for goaf areas, characterized in that, The goaf fire prevention system is used for fire prevention operations in the goaf during coal mining. The underground roadways include the panel main roadway, the return air main roadway, and the longwall face. The return air main roadway is connected to the panel main roadway to allow airflow. The goaf is located at the longwall face. During coal mining, airflow enters the goaf along the return air main roadway and exits from the panel main roadway. The goaf fire prevention system includes a casing expansion assembly, a liquid supply assembly, and a nitrogen injection assembly. At least a portion of the casing expansion assembly is inserted into a borehole in the sidewall and / or topwall of the goaf. There are at least two casing expansion assemblies, which are horizontally spaced within the goaf, and at least two casing expansion assemblies are correspondingly arranged with at least two boreholes; each borehole has a first region, a second region, and a third region spaced apart along the axial direction, and the casing expansion assemblies are respectively provided with a first hole (14), a second hole (15), and a third hole (16) in the first region, the second region, and the third region, respectively. The casing expansion assembly is connected to the interior of the borehole in a shunt manner; the casing expansion assembly is used to detect changes in oxygen and temperature at corresponding locations within the borehole; the nitrogen injection assembly is connected to at least a portion of the casing expansion assembly, and the nitrogen injection assembly is used to perform fire prevention and extinguishing operations at corresponding locations within the borehole by injecting nitrogen into at least a portion of the casing expansion assembly; the liquid supply assembly is connected to at least a portion of the casing expansion assembly, and the liquid supply assembly is used to drive at least a portion of the casing expansion assembly to expand, thereby driving the expanded portion to block at least one of the first hole (14), the second hole (15), and the third hole (16), and the expanded portion is used to isolate the blocked hole from the interior of the borehole, so that the first region, the second region, and the third region can be selectively connected to or disconnected from the interior of the casing expansion assembly; when the casing expansion assembly detects abnormal changes in oxygen or temperature in the second region, it drives the expanded portion to block the first hole (14) and the third hole (16), and the nitrogen injection assembly injects nitrogen into the second region through the second hole (15).

2. The fire prevention system for goaf areas according to claim 1, characterized in that, The sleeve expansion assembly includes a sleeve structure (10), an expansion structure (20), a connecting structure (30), and a gas delivery detection structure (40); the sleeve structure (10) has a receiving cavity (12); the expansion structure (20) and the connecting structure (30) are connected, and at least a portion of the expansion structure (20), the connecting structure (30), and the gas delivery detection structure (40) are disposed within the receiving cavity (12); the connecting structure (30) is used to cover a portion of the gas delivery detection structure (40); the first hole (14), the second hole (15), and the third hole (16) are also included. The expansion structure (20) is respectively installed on the casing structure (10); the expansion structure (20) is used to expand during fire prevention operations; when the expansion structure (20) is in the expanded state, the expanded part of the expansion structure (20) prevents the corresponding position of the casing structure (10) from communicating with the borehole; the gas delivery detection structure (40) is installed on the expansion structure (20), and the gas delivery detection structure (40) is used to detect the gas temperature and oxygen changes in the first area, the second area and the third area respectively; the gas delivery detection structure (40) is connected to the nitrogen injection assembly to deliver nitrogen when fire prevention is required.

3. The fire prevention system for goaf areas according to claim 2, characterized in that, The expansion structure (20) includes a single-layer expansion part (21) and at least two double-layer expansion parts (22). The single-layer expansion part (21) and the at least two double-layer expansion parts (22) are all disposed within the receiving cavity (12) and correspond one-to-one with the first hole (14), the second hole (15), and the third hole (16), respectively. The single-layer expansion part (21), the connecting structure (30), and the double-layer expansion parts (22) are sequentially connected along the axial direction of the casing structure (10). Adjacent double-layer expansion parts (22) are connected through a connecting structure (30). The single-layer expansion part (21) is located within the end of the casing structure (10) facing the borehole. 21) and the double-layer expansion section (22) expand during fire prevention operations to block the corresponding holes so that the sleeve structure (10) at the corresponding position is not connected to the borehole; the expansion structure (20) also includes at least five injection channels (23) and at least two bundled tube channels (24); the injection channels (23) are used to communicate with the liquid supply assembly to circulate liquid; the bundled tube channels (24) are used to pass wires and pipelines, the wires are electrically connected to the gas transmission detection structure (40), and the pipelines are respectively connected to the nitrogen injection assembly and the gas transmission detection structure (40); one single-layer expansion section (21) is provided with one injection channel (23) and one bundled tube channel (24) inside, and ... The double-layer expansion section (22) is provided with two injection channels (23) and one bundled tube channel (24) inside, and at least five injection channels (23) and at least two bundled tube channels (24) are not interconnected; the single-layer expansion section (21) is the first level, the double-layer expansion section (22) near the first level is the second level, and the double-layer expansion section (22) near the second level is the third level, and the first level, the second level and the third level correspond one-to-one with the first region, the second region and the third region respectively; the first level is provided with one injection channel (23) corresponding to the single-layer expansion section (21), and the second level is provided with one injection channel (23) corresponding to the single-layer expansion section (21). The third stage is provided with one injection channel (23) corresponding to the single-layer expansion section (22), four injection channels (23) corresponding to the double-layer expansion section (22), one bundled tube channel (24) corresponding to the single-layer expansion section (21), and one bundled tube channel (24) corresponding to the single-layer expansion section (21). There are at least three gas delivery detection structures (40), and at least three gas delivery detection structures (40) are provided in a one-to-one correspondence with one single-layer expansion section (21) and at least two double-layer expansion sections (22).

4. The fire prevention system for goaf areas according to claim 3, characterized in that, The single-layer expansion section (21) includes a single-layer expansion capsule (211); the two ends of the single-layer expansion capsule (211) are made of rigid materials for connection with other components, and the middle part of the single-layer expansion capsule (211) is made of elastic material for expansion by liquid injection through the liquid supply assembly; a first mounting groove (212) is provided on the side wall of one end of the single-layer expansion capsule (211), and the first mounting groove (212) is used to install at least a part of the corresponding gas transmission detection structure (40); a liquid injection channel (23) is provided on the end face of the single-layer expansion capsule (211) near the first mounting groove (212), and the liquid injection channel (23) is used to connect the interior of the single-layer expansion capsule (211) with the liquid supply assembly.

5. The fire prevention system for goaf areas according to claim 4, characterized in that, The double-layer expansion section (22) includes an outer expansion capsule (221), an inner expansion capsule (222), a connecting tube (224), and a first support member (225); both ends of the outer expansion capsule (221) and the inner expansion capsule (222) are made of rigid materials for connection with other components, and the middle parts of the outer expansion capsule (221) and the inner expansion capsule (222) are made of elastic materials for expansion by liquid injection through the liquid supply assembly; the outer expansion capsule (221) covers the outer periphery of the inner expansion capsule (222); The first support member (225) is disposed between the outer expansion capsule (221) and the inner expansion capsule (222); there are at least two first support members (225), each of which is spaced circumferentially along the outer wall of the inner expansion capsule (222), and the first support member (225) is used to support the outer expansion capsule (221); a second mounting groove (223) is provided on the side wall of one end of the outer expansion capsule (221), and the second mounting groove (223) is used to install the corresponding input... At least a portion of the gas detection structure (40); the inner expansion capsule (222) is provided with at least three injection channels (23) and at least one bundle tube channel (24) on its end face near the second mounting groove (223), wherein, among the at least three injection channels (23), one injection channel (23) is used to connect the single-layer expansion capsule (211) to the liquid supply assembly, one injection channel (23) is used to connect the outer expansion capsule (221) to the liquid supply assembly, and one injection channel (24) is used to connect the outer expansion capsule (221) to the liquid supply assembly. The inner expansion capsule (222) is used to connect the inner expansion capsule (222) to the liquid supply assembly; the bundle tube channel (24) is used to connect the gas delivery detection structure (40) of the previous stage to the nitrogen injection assembly; the connecting tube (224) is disposed on the inner expansion capsule (222), one end of the connecting tube (224) is connected to the liquid injection channel (23), and the other end of the connecting tube (224) is connected to the outer expansion capsule (221), and the connecting tube (224) is used to connect the outer expansion capsule (221) to the liquid supply assembly.

6. The fire prevention system for goaf areas according to claim 2, characterized in that, The casing structure (10) further includes a casing body (11) and a mesh tube (13) disposed on the casing body (11); there are at least three mesh tubes (13), which are spaced apart along the axial direction of the casing body (11); the first hole (14), the second hole (15) and the third hole (16) are respectively disposed on one of the mesh tubes (13); the casing body (11) forms the receiving cavity (12), which is connected to the borehole through the mesh tubes (13); at least three mesh tubes (13) correspond one-to-one with the first region, the second region and the third region, and the gas in the borehole enters the receiving cavity (12) through the mesh tubes (13) so that the corresponding gas delivery detection structure (40) can detect changes in gas temperature and oxygen.

7. The fire prevention system for goaf areas according to claim 3, characterized in that, The connecting structure (30) includes a connecting tube (31); the expansion structure (20) includes a single-layer expansion part (21) and at least two double-layer expansion parts (22); the single-layer expansion part (21), the connecting tube (31), and the double-layer expansion parts (22) are connected sequentially along the axial direction of the sleeve structure (10), and two adjacent double-layer expansion parts (22) are connected through a connecting tube (31); the side wall of the connecting tube (31) is provided with a through-hole in the axial direction. A through-line groove (311) is provided for the pipeline connected to the liquid injection channel (23), the wire electrically connected to the gas delivery detection structure (40), and the pipeline connected to the nitrogen injection assembly and the gas delivery detection structure (40) to enter the interior of the connecting pipe body (31).

8. The fire prevention system for goaf areas according to claim 2, characterized in that, The gas delivery detection structure (40) includes a sensor (41), a second support member (42), a gas delivery pipe (43), and a wire (44). The sensor (41) is disposed inside the gas delivery pipe (43), and the second support member (42) is disposed between the sensor (41) and the gas delivery pipe (43). There are at least two second support members (42), which are spaced apart along the circumferential direction of the outer wall of the sensor (41). The second support member (42) is disposed between the sensor (41) and the gas delivery pipe (43). The sensor (41) detects the gas temperature near the corresponding area inside the borehole. The sensor (41) is electrically connected to the wire (44). The wire (44) is disposed inside the gas delivery pipe (43) and connected to an electrical wire to transmit current. The gas delivery pipe (43) is connected to the nitrogen injection assembly to deliver nitrogen.

9. A method for fire prevention in goaf areas, characterized in that, The goaf fire prevention method is applied to the goaf fire prevention system according to any one of claims 1 to 8, and the goaf fire prevention method has a deployment step; The borehole also has a fourth region, and the first region, the second region, the third region and the fourth region are spaced apart along the axial direction of the borehole; The sleeve expansion assembly includes a sleeve structure (10), an expansion structure (20), a connecting structure (30), and a gas delivery detection structure (40); the sleeve structure (10) includes four mesh tubes (13) spaced apart along its axial direction; the expansion structure (20) includes a single-layer expansion part (21) and three double-layer expansion parts (22), with the single-layer expansion part (21) and the three double-layer expansion parts (22) corresponding one-to-one with the four mesh tubes (13); there are four gas delivery detection structures (40), with each of the four gas delivery detection structures (40) corresponding one-to-one with the single-layer expansion part (21) and the three double-layer expansion parts (22); One single-layer expansion section (21) and three double-layer expansion sections (22) are arranged sequentially and spaced apart along the axial direction within the sleeve structure (10). The single-layer expansion section (21) is the first level, the double-layer expansion section (22) closer to the first level is the second level, the double-layer expansion section (22) closer to the second level is the third level, and the double-layer expansion section (22) closer to the third level is the fourth level. The first level, the second level, the third level, and the fourth level correspond one-to-one with the first region, the second region, the third region, and the fourth region, respectively. The deployment steps include: along the advancing direction of the longwall face, using a casing drilling device to construct a first borehole with a diameter of 100 mm in the return airway towards the goaf, perpendicular to the return airway direction, and placing the casing expansion assembly in the first borehole; wherein, when the initial collapse step distance of the goaf is greater than or equal to 50 meters, the first borehole is set at a position 30 meters away from the main roadway of the panel; when the initial collapse step distance of the goaf is greater than or equal to 40 meters and less than 50 meters, the first borehole is set at a position 20 meters away from the main roadway of the panel; after the casing expansion assembly is installed, one single-layer expansion part (21) and three double-layer expansion parts (22) are connected to the liquid supply assembly, and four gas transmission detection structures (40) are connected to the nitrogen injection assembly. Connect; As coal mining operations continue, the overburden of the goaf roof collapses continuously. During the third collapse, a second borehole is constructed at a set distance from the first casing expansion assembly along the advancing direction of the longwall face, and the second casing expansion assembly is placed in the second borehole. In the second borehole, one single-layer expansion part (21), three double-layer expansion parts (22), and four mesh pipes (13) in the casing expansion assembly are staggered from one single-layer expansion part (21), three double-layer expansion parts (22), and four mesh pipes (13) in the casing expansion assembly in the first borehole. The casing expansion assemblies are sequentially deployed according to the advancing progress of the longwall face until the longwall face is mined out.

10. The fire prevention method for goaf areas according to claim 9, characterized in that, The fire prevention method for goaf areas also includes fire prevention steps; There is also a third borehole in the goaf area; The fire prevention steps include: when an abnormal change in oxygen or temperature occurs in the third region of the second borehole, air is pumped into the first and third boreholes, and the liquid supply assembly is controlled to inject liquid into the first and fourth stages of the first and third boreholes. The expansion portion of the casing expansion assembly seals the corresponding mesh tube (13), so that the first and fourth regions of the first and third boreholes are not connected to the interior of the casing structure (10) inside their holes. Under negative pressure, the mesh tube (13) located in the second and third stages of the first and third boreholes is circulated by the negative pressure. The extraction affects the leakage airflow of the second borehole; at the same time, the liquid supply component is controlled to inject liquid into the first, second and fourth stages of the second borehole to seal the mesh tube (13) in the first, second and fourth areas respectively. Then, the nitrogen injection component is controlled to inject nitrogen into the gas transmission detection structure (40) corresponding to the third stage in the second borehole to extinguish the fire in the third area of ​​the second borehole that is abnormal. After the nitrogen injection is completed, the pressure of the expanded structure (20) is released, and the gas transmission detection structure (40) is used to detect the oxygen change and gas temperature near the mesh tube (13).

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