Three-stage chain type goaf harmful gas prevention and control method in pre-disaster-in-disaster-after-disaster mode

Abstract

The invention discloses a three-level chain type goaf harmful gas prevention and control method in a pre-disaster-in-disaster-after-disaster mode, and belongs to the technical field of mine safety monitoring. According to the method, a chain type management system of fast pre-disaster early warning, strong protection in the disaster and non-expansion after the disaster is constructed, a goaf ad hoc network early warning technology is adopted before the disaster, and real-time monitoring and fast early warning of parameters such as gas and temperature are achieved; in the disaster, on the basis of a gas and coal spontaneous combustion disaster coupling mechanism, an injection-plugging-extraction-control cooperative protection method is adopted, gas prevention and control serve as the core, and coal spontaneous combustion is cooperatively controlled through nitrogen injection inerting, plugging air leakage at corners of plugging bags, gas extraction and ventilation system regulation and control; and after the disaster, explosion-proof dry powder is arranged in the roadway to prevent the disaster from spreading. The goaf gas and fire coupling disaster is efficiently prevented and controlled through technical cooperation of all stages.

Description

Technical Field

[0001] This invention belongs to the field of mine safety monitoring technology, specifically involving a three-level chain prevention and control method for harmful gases in goaf areas before, during, and after a disaster. Background Technology

[0002] Goaf areas are underground spaces formed after coal mining. Due to factors such as residual coal seams, gas accumulation, and air leakage, they are prone to coupled disasters of gas and coal spontaneous combustion. Gas explosions and coal spontaneous combustion fires promote each other, not only damaging mine facilities but also seriously threatening the lives of workers. Therefore, efficient disaster management methods are needed.

[0003] Existing research reports on technologies for preventing and controlling disasters in goaf areas include:

[0004] Application No. 202111270139.4 discloses a fire early warning sensor for spontaneous combustion in coal mine goaf areas, including a circuit board and a power supply. The sensor includes a switch, which includes an elastic element, a gasket wire, a low-melting-point material structural component, and a connector. The end of the elastic element is connected to the gasket wire, and the low-melting-point material structural component is disposed below the gasket wire. Connectors are disposed at both ends of the bottom of the switch. After the low-melting-point material structural component melts, the gasket wire descends and connects with the connector. One connector of the switch is connected to the power supply through the circuit board, and the other connector is connected to the UWB chip through the circuit board.

[0005] The aforementioned existing technology forms an interlaced sensing network system by horizontally arranging multiple sets of optical cables at the top of the goaf and installing optical fiber stress sensors, optical fiber displacement sensors, and optical fiber micro-vibration sensors, which can provide early warning of goaf collapse.

[0006] However, existing technologies still have many shortcomings: (1) the coverage of pre-disaster protection is small and the data transmission delay is high, making it difficult to achieve rapid early warning; (2) the protection efficiency during the disaster is low, and traditional leak-proof materials are mostly chemical agents, which pose environmental pollution problems; after the disaster, there is a lack of effective explosion-proof and fire-fighting measures, and the disaster is easy to spread and expand, causing greater losses.

[0007] This shows that the existing technology needs further improvement. Summary of the Invention

[0008] The purpose of this invention is to provide a three-level chain prevention and control method for harmful gases in goaf areas, covering the pre-disaster, during-disaster, and post-disaster phases. Through the synergy of technologies at each stage, this method achieves efficient prevention and control of gas-fire coupling disasters in goaf areas.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A three-tiered chain control method for hazardous gases in goaf areas, encompassing pre-disaster, during-disaster, and post-disaster phases, includes the following steps:

[0011] a. Deploy the required monitoring system and use it for disaster early warning. The specific steps are as follows:

[0012] a1. In the goaf area, a number of fire source positioning balls are arranged in a rectangular network with a "tendency every 10m + advance every 10m" pattern to collect the temperature, CO concentration, and O2 concentration of the goaf area.

[0013] a2. Power each fire source positioning ball is supplied through an explosion-proof battery pack; a card reader substation one is set at the edge of the goaf area, and a card reader substation two is set at a fixed position in the working face roadway; both card reader substation one and card reader substation two are connected to the mining substation, and the mining substation is connected to the switch and the host computer software system in sequence.

[0014] a3. A communication transmission layer is deployed in the goaf area. The communication transmission layer adopts spread spectrum communication technology and is combined with self-organizing network protocol to realize wireless multi-hop communication between hardware devices in the hardware system. The fire source positioning ball in the rectangular network realizes the step-by-step transmission of signals through this communication method.

[0015] a4. The host computer software system is equipped with a first-level early warning module, a second-level early warning module, and a third-level early warning module;

[0016] b. Disaster prevention:

[0017] b1. First, nitrogen is injected into the goaf so that the nitrogen gas can be evenly diffused in the goaf to exert an inerting effect;

[0018] The formula for calculating nitrogen injection amount is shown in equation (1):

[0019] Q=60Q0(C1-C2) / (C N +C2-1) (1)

[0020] In formula (1): Q is the nitrogen injection amount; Q0 is the air leakage in the oxidation zone of the goaf; C1 is the original oxygen concentration in the oxidation zone of the goaf; C2 is the fireproof inerting index; C N To determine the concentration of the injected inert gas;

[0021] b2. The leak-sealing bags are placed in the leaky corner of the goaf area, and the leak-sealing bags are equipped with grouting ports and air injection ports.

[0022] b3. Gas extraction: An extraction system is used to extract gas from the goaf, so that the gas concentration in the goaf is <0.8%CH4.

[0023] b4. Ventilation: Select the ventilation method and ventilation volume according to the gas concentration;

[0024] c. Install explosion-proof dry powder devices in the roadways surrounding the goaf and in the connecting roadways:

[0025] The explosion-proof dry powder device includes a dry powder storage tank, a triggering mechanism, a powder spraying pipeline, a solenoid valve, a powder spraying hole, a shock wave transmission device, a transmission rod, and a connecting rod. When a gas explosion or fire is detected in the goaf, the triggering mechanism sends a signal to the solenoid valve. After the solenoid valve opens, the high-pressure nitrogen in the dry powder storage tank pushes the dry powder through the powder spraying pipeline and sprays it into the roadway. The powder spraying time is <5s, forming an explosion-proof barrier with a thickness of ≥0.5m, isolating the flame and gas and preventing their spread.

[0026] In the above-mentioned three-level chain prevention and control method for hazardous gases in goaf areas, which covers the "pre-disaster-disease-post-disaster" stage, step a1, "every 10m along the trend" means that a measuring point is arranged every 10m along the trend behind the working face frame, and several measuring points form the first monitoring line; "supplement every 10m along the advance" means that a new trend monitoring line is added behind the new working face frame, which is parallel to the first monitoring line and forms a rectangular network with a longitudinal spacing of 10m.

[0027] The above-mentioned three-level chain prevention and control method for harmful gases in goaf areas, which covers "pre-disaster-disease-post-disaster", includes each ignition source positioning ball consisting of a sphere, on the surface of which are distributed gas sensors, temperature sensors, CO concentration detection sensors and O2 concentration detection sensors.

[0028] The above-mentioned three-level chain prevention and control method for harmful gases in goaf areas, which covers "pre-disaster, during-disaster, and post-disaster", sets warning thresholds for the first-level warning module, the second-level warning module, and the third-level warning module. When the data monitored by the sensor exceeds the warning threshold, the graded warning is triggered.

[0029] The above-mentioned three-level chain prevention and control method for harmful gases in goaf areas, which covers the period from pre-disaster to during-disaster to post-disaster, includes a plugging bag comprising a bag body, on the surface of which polyvinyl chloride is coated, and the thickness of the polyvinyl chloride layer is 0.2 mm.

[0030] The aforementioned three-tiered chain control method for hazardous gases in goaf areas, encompassing pre-disaster, during-disaster, and post-disaster phases, employs a water-ring vacuum pump in the extraction system. The extraction negative pressure is set at 10-20 kPa. Gas concentration and flow sensors are installed every 50-100 meters along the extraction pipeline to monitor the extraction effect in real time.

[0031] The aforementioned three-tiered chain prevention and control method for hazardous gases in goaf areas, covering pre-disaster, during-disaster, and post-disaster phases, utilizes a fire source positioning sphere with strong signal capabilities, which are achieved through the following design:

[0032] Integrated miniaturized high-gain omnidirectional antenna with a gain ≥5dBi and antenna radiation efficiency ≥85%, suitable for signal coverage requirements in complex spaces of mining subsidence areas.

[0033] It adopts a spread spectrum communication module with a working frequency of 433MHz and an output power of ≤20dBm. In the environment of coal gangue filling in the goaf, the signal penetration distance is ≥20m, and the transmission distance is ≥50m in the unobstructed environment.

[0034] Built-in channel detection and frequency hopping mechanism automatically avoids interference frequency bands, achieving a communication bit error rate of ≤10% in interference signal environments ranging from -85dBm to -40dBm. -5 This ensures stable signal transmission.

[0035] The aforementioned three-level chain prevention and control method for hazardous gases in goaf areas, covering "pre-disaster, during-disaster, and post-disaster" stages, automatically adjusts the network transmission path at the communication transmission layer to ensure stable data upload when one of the fire source locating balls, card reader substation one, or card reader substation two malfunctions.

[0036] The above-mentioned three-level chain prevention and control method for harmful gases in goaf areas, which covers the "pre-disaster-disease-post-disaster" stage, has a temperature sensor triggering temperature of 80-100℃ and a pressure sensor triggering pressure of 0.15-0.2MPa.

[0037] Compared with the prior art, the present invention brings the following beneficial technical effects:

[0038] (1) The present invention provides a three-level chain prevention and control method for harmful gases in mining subsidence areas before, during and after disasters. The chain management system is complete: it covers the entire process before, during and after disasters, and the technologies at each stage are coordinated and linked to avoid the limitations of single technology prevention and control and improve the systematic nature of disaster prevention and control.

[0039] (2) Rapid and accurate early warning: The self-organizing network early warning system has a wide coverage and fast data transmission. The three-level early warning mechanism can take targeted measures according to the risk level to reduce false alarms and missed alarms.

[0040] (3) High efficiency and environmental protection: The “injection-blocking-extraction-control” collaborative protection takes gas prevention and control as the core and takes into account coal spontaneous combustion control, resulting in high protection efficiency; the new green capsule is degradable, has no environmental pollution, and meets the requirements of green mines.

[0041] (4) Reliable post-disaster control: The explosion-proof dry powder device is sensitive to triggering and sprays powder quickly, which can effectively form an explosion-proof barrier to prevent the disaster from spreading and reduce disaster losses.

[0042] (5) Strong applicability: Each technical parameter can be adjusted according to the size of the goaf, the amount of gas emission, and the spontaneous combustion characteristics of the coal seam, making it suitable for different types of high-gas, spontaneously combustible goafs. Attached Figure Description

[0043] The present invention will be further described below with reference to the accompanying drawings:

[0044] Figure 1This is a flowchart of the three-level chain prevention and control method for gas and fire disasters in goaf areas according to the present invention;

[0045] Figure 2 This is a schematic diagram of the layout of the self-organizing network early warning system for goaf areas according to the present invention;

[0046] Figure 3 A schematic diagram of the "injection-blocking-extraction-control" protection system layout;

[0047] Figure 4 This is a schematic diagram of the layout of the explosion-proof dry powder device;

[0048] In the diagram: 1-Goaf area of ​​the working face; 2-Explosion-proof battery pack; 3-Wireless multi-parameter sensor; 4-DC regulated power supply; 5-Card reader substation one; 6-Card reader substation two; 7-Mine substation; 8-Switchboard switch; 9-Host computer software system; 10-Nitrogen production workshop; 11-Gas extraction pump room; 12-Plugging bag; 13-High-level borehole; 14-Gas extraction pipeline; 15-Nitrogen injection pipeline; 16-Intake airway; 17-Return airway; 18-Shock wave transmission device; 19-Transmission rod; 20-Connecting rod; 21-Underground explosion-proof device body. Detailed Implementation

[0049] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0050] In the description of this application, the words "one," "two," etc., are used only to distinguish different objects and do not limit the quantity or order of execution, nor do they imply that they must be different. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0051] The technical solution of this application will be further described in detail below with reference to the accompanying drawings.

[0052] like Figure 1 As shown, this invention proposes a three-level chain prevention and control method for harmful gases in goaf areas, which combines pre-disaster rapid early warning technology, "injection-blocking-extraction-control" strong protection technology during the disaster, and post-disaster non-expansion technology. The technologies at each stage work together to achieve efficient prevention and control of gas and fire coupled disasters in goaf areas.

[0053] The method of the present invention includes the following steps:

[0054] Step 1: Pre-disaster rapid early warning technology: Deploy the necessary monitoring systems, combined with... Figures 2 to 4As shown, the monitoring system consists of sensor nodes, relay nodes, and sink nodes. Specifically, it is designed to achieve real-time monitoring and fire early warning of multiple parameters such as temperature, carbon monoxide (CO), and oxygen (O2) in the goaf by constructing a fully covered self-organizing network that includes an explosion-proof battery pack 2, a wireless multi-parameter sensor 3, a DC regulated power supply 4, a card reader substation 1 5, a card reader substation 2 6, a mining substation 7, a switch 8, and a host computer software system 9.

[0055] The aforementioned explosion-proof battery pack is a DXH18 intrinsically safe battery pack, enabling low-power operation. The wireless multi-parameter sensor is a GD3W mining wireless multi-parameter sensor, which transmits the collected data to card reader substation one and card reader substation two via a wireless self-organizing network. Card reader substation one is located at the edge of the goaf, and card reader substation two is located at a fixed position in the working face roadway. Both serve as data aggregation nodes, receiving monitoring data from the fire source positioning ball and performing preliminary processing. The DC regulated power supply is a KDW660-24B mining explosion-proof intrinsically safe DC regulated power supply. Card reader substation one is a KJ1879J-F2 mining intrinsically safe card reader substation, card reader substation two is a KJ1879J-F1 mining intrinsically safe card reader substation, and the mining substation is a KJ1879J-F mining intrinsically safe substation.

[0056] The fire source positioning sphere adopts a rectangular network layout with "inclination along the rear edge of the working face and dynamic replenishment as the working face advances". Combined with low power consumption design and spread spectrum communication technology, it has self-organizing network, self-positioning and penetration communication functions. Each node can automatically form a wireless network and realize multi-hop routing transmission to ensure stable data upload. The host computer software system supports real-time monitoring, historical curve analysis, parameter report generation and visualization display, and can accurately locate the fire source position.

[0057] Based on the coal mine safety regulations, three levels of early warning thresholds are set (as shown in Table 1). When the monitoring data exceeds the corresponding threshold, the system automatically issues an audible and visual alarm and pushes the early warning information to the mobile APP of the management personnel. The first-level early warning only reminds the monitoring personnel to strengthen monitoring, the second-level early warning initiates on-site inspection, and the third-level early warning immediately initiates strong protection measures during the disaster.

[0058] Table 1 Early Warning Threshold Classification Table

[0059]

[0060] The specific steps for using a monitoring system for disaster early warning are as follows:

[0061] (1) In goaf 1, a number of fire source positioning balls are arranged in a rectangular network of “tendency every 10m + advance every 10m” to collect the temperature, CO concentration and O2 concentration of the goaf.

[0062] (2) Power each fire source positioning ball is supplied through an explosion-proof battery pack; a card reading substation is set at the edge of the goaf area, and a card reading substation is set at a fixed position in the working face roadway; both card reading substation one and card reading substation two are connected to the mining substation, and the mining substation is connected to the switch and the host computer software system in sequence.

[0063] (3) A communication transmission layer is deployed in the goaf area. The communication transmission layer adopts spread spectrum communication technology and combines self-organizing network protocol to realize wireless multi-hop communication between hardware devices in the hardware system. The fire source positioning ball in the rectangular network realizes the step-by-step transmission of signals through this communication method.

[0064] (4) By combining the first-level early warning module, the second-level early warning module, and the third-level early warning module with the early warning thresholds at each level, the strong protection steps during the disaster are initiated.

[0065] Step Two: Disaster-Responsive "Injection-Blocking-Extraction-Control" Enhanced Protection Technology:

[0066] Based on the coupling mechanism of gas and coal spontaneous combustion (gas accumulation provides fuel for explosion, the heat released by coal spontaneous combustion accelerates gas desorption, and air leakage both provides oxygen for coal spontaneous combustion and promotes gas diffusion), with gas prevention as the core, coal spontaneous combustion is controlled in a coordinated manner. The specific steps are as follows:

[0067] (1) Nitrogen inerting

[0068] The formula for calculating nitrogen injection amount is:

[0069] Q=60Q0(C1-C2) / (C N +C2-1) (1)

[0070] In formula (1): Q is the nitrogen injection rate (m³ / h); Q0 is the air leakage rate in the oxidation zone of the goaf (m³ / h). 3 / min); C1 is the original oxygen concentration in the oxidation zone of the goaf, taken as 10% to 15%; C2 is the fire-resistant inerting index (natural critical oxygen concentration of coal), 7%; C N The concentration of the injected inert gas is set at 97%.

[0071] Nitrogen is supplied to the nitrogen production pipeline through the nitrogen production workshop 10. The nitrogen injection pipeline 15 uses seamless steel pipes with a diameter of 100-150mm and is arranged in the intake airway 16 around the goaf. A nitrogen injection branch pipe is set every 20-30m. The pipeline is buried into the goaf using a step-by-step burial method to keep the nitrogen injection port within the oxidation zone. Pressure sensors and flow regulating valves are installed at the ends of the branch pipes. The nitrogen injection pressure is adjusted according to the key parameters of the goaf to ensure that the nitrogen diffuses evenly into the goaf and achieves a good inerting effect.

[0072] (2) Leak-stopping bag corner leak-stopping

[0073] The load-bearing layer of the plugging bag material is made of high-strength polyester filament fiber, and the sealing coating material is a composite material of polyvinyl chloride. The overall thickness of the selected materials is 1 mm, with high-strength polyester filament fiber of 0.4 mm thickness as the main body, coated with a 0.2 mm polyvinyl chloride airtight layer on each side. The material used in the plugging bag has a tensile strength greater than 55 MPa, an elastic modulus greater than 700 MPa, and possesses flame-retardant and antistatic properties, meeting all requirements for use in underground coal mines. The plugging bag is equipped with grouting and air-filling ports, enabling rapid connection between grouting and inflation, improving work efficiency. The plugging bag 12 has dimensions of 2m × 2m × 1m, and the injection method is designed to inflate first and then grout. The process involves first inflating and shaping, then grouting for stabilization, enabling long-distance pipeline grouting. Reinforcing straps are also included to address the deformation issue during grouting.

[0074] In the corner of the goaf, where air leakage is located (determined through smoke testing), plugging bags are pre-suspended on the roadway side using hooks, with the bags close to the roadway wall and their tops suspended 2 meters from the roadway floor. After the plugging bags are suspended, a three-way grouting pipe is connected to the grouting port of the bag. The other two ends of the three-way grouting pipe are connected to the A and B outlets of the grouting pump via two grout delivery pipes (Φ=25 mm), respectively. After the plugging bags are pushed into the windbreak curtain, they are inflated through the pre-reserved air injection pipeline. After inflation, the air injection port is sealed. Material A and Material B are poured into mixing tanks A and B respectively. Water is added according to the water-cement ratio, and the mixtures are thoroughly stirred. The grouting pump is started to transport the grout from mixing tanks A and B to the mixing pipe through the delivery pipe. After the grout A and grout B are fully mixed in the mixing pipe, they are injected into the plugging bags. After the plugging bags harden, the limiting plate is removed. The plugging bags are arranged at 1.5 m intervals. After all the plugging bags have been injected and filled and pushed into the goaf, the plugging effect is evaluated.

[0075] (3) Gas extraction

[0076] Based on the gas distribution characteristics of the goaf (determined through numerical simulation or field testing), high-level boreholes are arranged in the fracture zone above the goaf, with a diameter of 100-150 mm, a depth of 50-100 m, and a spacing of 15-25 m. Φ80-120 mm screen pipes are inserted into the boreholes, and filter screens (0.5-1 mm aperture) are wrapped around the screen pipes to prevent coal slag blockage. Goaf-buried pipes with a diameter of Φ108 mm are arranged along the goaf direction at the return air corner. A gas drainage pipeline 14 is installed in the return air roadway 17, and the gas drainage pump station 11 is connected to the gas drainage pipeline 14.

[0077] The extraction system uses a water ring vacuum pump, with the extraction negative pressure set at 10-20 kPa (a larger value is used when the gas concentration is high). The extraction flow rate is adjusted by a regulating valve to ensure that the gas concentration in the goaf is <0.8% CH4. Gas concentration sensors and flow sensors are installed every 50-100 m in the extraction pipeline to monitor the extraction effect in real time. When the gas concentration is <0.5% CH4, the extraction negative pressure is appropriately reduced by 5-10% to save energy.

[0078] (4) Ventilation system control

[0079] Ventilation method selection: Based on the size of the goaf and the coal seam occurrence conditions, select either Y-type or U+L-type ventilation: Y-type ventilation is suitable for goafs with a strike length > 800m, reducing air leakage in the goaf by diverting air through return air roadways and tail roadways; U+L-type ventilation is suitable for goafs with an inclined length > 300m, increasing return air channels through connecting roadways to reduce the risk of gas accumulation.

[0080] Airflow adjustment strategy: Real-time monitoring of gas concentration, temperature, and oxygen concentration in the goaf. When the gas concentration > 0.8% CH4, increase the main ventilation fan airflow by 10-20% (achieved by adjusting the fan blade angle). When the temperature > 50℃ or the carbon monoxide concentration > 50ppm, appropriately reduce the airflow by 5-10% and close some leakage channels to ensure that the oxygen concentration in the goaf is < 18% O2 (to suppress coal spontaneous combustion). After the ventilation system is adjusted, monitor the roadway wind speed using a wind speed sensor (measurement range 0-10m / s, accuracy ±0.1m / s) to ensure that the wind speed is < 8m / s (to prevent gas stratification).

[0081] Step 3: Post-disaster non-scaling technology

[0082] In the surrounding roadways and connecting roadways of the goaf, explosion-proof dry powder devices are installed: the explosion-proof dry powder device includes a dry powder storage tank, an underground explosion-proof device body 21, a triggering mechanism, a powder injection pipeline, a solenoid valve, a powder injection hole, a shock wave transmission device 18, a transmission rod 19 and a connecting rod 20. The dry powder storage tank has a capacity of 300-500kg, is made of stainless steel, and has a pressure resistance of ≥1.0MPa.

[0083] Along the length of the roadway, the explosion-proof dry powder devices are spaced 20-30m apart (with smaller values ​​for high-risk areas). The powder spraying pipeline covers the roadway cross-section (width and height are both 1.1 times the roadway dimensions) to ensure uniform powder spraying. The temperature sensor of the triggering mechanism has a trigger temperature of 80-100℃ (above the critical temperature for coal spontaneous combustion), and the pressure sensor has a trigger pressure of 0.15-0.2MPa (the pressure threshold of the gas explosion shock wave). The manual trigger button is located on the side wall of the roadway at a height of 1.5-1.8m for easy operation.

[0084] Operation process: When a gas explosion or fire is detected in the goaf, the triggering mechanism sends a signal to the solenoid valve. The solenoid valve opens, and the high-pressure nitrogen gas (pressure 0.6-0.8MPa) in the dry powder storage tank pushes the dry powder through the powder spraying pipeline to spray into the roadway. The powder spraying time is <5s, forming an explosion barrier with a thickness of ≥0.5m, isolating the flame and gas, and preventing the disaster from spreading to other areas.

[0085] This invention combines pre-disaster early warning, "injection-blocking-extraction-control" strong protection technology during a disaster, and post-disaster non-expansion technology. In the event of a gas and fire disaster, nitrogen is injected into the goaf through the nitrogen production workshop and the nitrogen injection pipeline 15 arranged in the intake airway 16 to inertize the goaf. According to the gas distribution in the goaf, the gas extraction pump room 11 is adjusted, and gas extraction is carried out by the gas extraction pipeline 14 arranged in the return airway 17 and the high-level borehole 13. Leakage bags 12 are used to block air leaks in the intake and return air corners. Each prevention and control method is reasonably adjusted according to the synergistic mechanism of gas and fire disasters.

[0086] If the disaster reaches an uncontrollable stage, an explosion-proof dry powder device is installed in the roadway. The device is suspended from the top of the roadway by a connecting rod 20. After receiving the explosion shock wave, the shock wave is transmitted to the explosion-proof device body 21 underground through the transmission rod 19, forming a mist-like ultra-fine dry powder explosion-proof barrier to prevent the further spread of the explosion shock wave and achieve the purpose of preventing the disaster from escalating.

[0087] Any parts not mentioned in this invention can be achieved by referring to existing technologies.

[0088] Those skilled in the art should recognize that the above embodiments are only used to illustrate this application and are not intended to limit this application. Any appropriate changes and variations made to the above embodiments within the essential spirit and scope of this application fall within the scope of protection claimed in this application.

Claims

1. A three-stage chain-based prevention and control method for harmful gases in goaf areas, encompassing pre-disaster, during-disaster, and post-disaster phases, characterized in that... Includes the following steps: a. Deploy the required monitoring system and use it for disaster early warning. The specific steps are as follows: a1. In the goaf area, a number of fire source positioning balls are arranged in a rectangular network with "tendency every 10m + advance every 10m" to collect the temperature, CO concentration and O2 concentration of the goaf area. a2. Power each fire source positioning ball is supplied through an explosion-proof battery pack; a card reader substation one is set at the edge of the goaf area, and a card reader substation two is set at a fixed position in the working face roadway; both card reader substation one and card reader substation two are connected to the mining substation, and the mining substation is connected to the switch and the host computer software system in sequence. a3. A communication transmission layer is deployed in the goaf area. The communication transmission layer adopts spread spectrum communication technology and is combined with self-organizing network protocol to realize wireless multi-hop communication between hardware devices in the hardware system. The fire source positioning ball in the rectangular network realizes the step-by-step transmission of signals through this communication method. a4. The host computer software system is equipped with a first-level early warning module, a second-level early warning module, and a third-level early warning module; b. Disaster prevention: b1. First, nitrogen is injected into the goaf so that the nitrogen gas can be evenly diffused in the goaf to exert an inerting effect; The formula for calculating nitrogen injection amount is shown in equation (1): Q=60Q0(C1-C2) / (C N +C2-1) (1); In formula (1): Q is the nitrogen injection amount; Q0 is the air leakage in the oxidation zone of the goaf; C1 is the original oxygen concentration in the oxidation zone of the goaf; C2 is the fireproof inerting index; C N To determine the concentration of the injected inert gas; b2. The leak-sealing bags are placed in the leaky corner of the goaf area, and the leak-sealing bags are equipped with grouting ports and air injection ports. b3. Gas extraction: An extraction system is used to extract gas from the goaf, so that the gas concentration in the goaf is <0.8% CH4. b4. Ventilation: Select the ventilation method and ventilation volume according to the gas concentration; c. Install explosion-proof dry powder devices in the roadways surrounding the goaf and in the connecting roadways: The explosion-proof dry powder device includes a dry powder storage tank, a triggering mechanism, a powder spraying pipeline, a solenoid valve, a powder spraying hole, a shock wave transmission device, a transmission rod, and a connecting rod. When a gas explosion or fire is detected in the goaf, the triggering mechanism sends a signal to the solenoid valve. After the solenoid valve opens, the high-pressure nitrogen in the dry powder storage tank pushes the dry powder through the powder spraying pipeline and sprays it into the roadway. The powder spraying time is <5s, forming an explosion-proof barrier with a thickness of ≥0.5m, isolating the flame and gas and preventing their spread.

2. The three-stage chain control method for hazardous gases in goaf areas according to claim 1, characterized in that: In step a1, "every 10m along the trend" means that a measuring point is arranged every 10m along the trend behind the working face frame, and several measuring points form the first monitoring line; "supplement every 10m along the advance" means that a new trend monitoring line is added behind the new working face frame, parallel to the first monitoring line, forming a rectangular network with a longitudinal spacing of 10m.

3. The three-stage chain control method for hazardous gases in goaf areas according to claim 1, characterized in that: Each fire source locating ball includes a sphere, on the surface of which are distributed a gas sensor, a temperature sensor, a CO concentration detection sensor, and an O2 concentration detection sensor.

4. The three-stage chain control method for hazardous gases in goaf areas according to claim 1, characterized in that: The Level 1, Level 2, and Level 3 early warning modules set early warning thresholds. When the data monitored by the sensors exceeds the early warning threshold, a tiered early warning is triggered.

5. The three-stage chain control method for hazardous gases in goaf areas according to claim 1, characterized in that: The leak-stopping bag includes a bag body, and polyvinyl chloride is coated on the surface of the bag body, forming a polyvinyl chloride layer with a thickness of 0.2 mm.

6. The three-stage chain control method for hazardous gases in goaf areas according to claim 1, characterized in that: The extraction system uses a water ring vacuum pump, with the extraction negative pressure set at 10-20 kPa. Gas concentration sensors and gas flow sensors are installed every 50-100 m along the gas extraction pipeline to monitor the extraction effect in real time.

7. The three-stage chain control method for hazardous gases in goaf areas according to claim 1, characterized in that: The fire source positioning ball has a strong signal capability, which is achieved through the following design: Integrated miniaturized high-gain omnidirectional antenna with a gain ≥5dBi and antenna radiation efficiency ≥85%, suitable for signal coverage requirements in complex spaces of mining subsidence areas. It adopts a spread spectrum communication module with a working frequency of 433MHz and an output power of ≤20dBm. In the environment of coal gangue filling in the goaf, the signal penetration distance is ≥20m, and the transmission distance is ≥50m in the unobstructed environment. Built-in channel detection and frequency hopping mechanism automatically avoids interference frequency bands, achieving a communication bit error rate of ≤10% in interference signal environments ranging from -85dBm to -40dBm. -5 This ensures stable signal transmission.

8. The three-stage chain control method for hazardous gases in goaf areas according to claim 1, characterized in that: When one of the fire source locating balls, card reader substation one, or card reader substation two malfunctions, the communication transmission layer automatically adjusts the network transmission path to ensure stable data upload.

9. The three-stage chain control method for hazardous gases in goaf areas according to claim 1, characterized in that: The temperature sensor of the triggering mechanism has a triggering temperature of 80-100℃, and the pressure sensor has a triggering pressure of 0.15-0.2MPa.

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