Intelligent monitoring and grading prevention and control device and method for coal spontaneous combustion in goaf

Abstract

The application discloses a kind of goaf coal spontaneous combustion intelligent monitoring and grading prevention and control device and method.Device is arranged in goaf behind coal mining face, through periodic air sampling probe detection, gas is detected in turn by temperature, CO and C2H2 sensor, and by intelligent analyzer discerns coal spontaneous combustion hazard and its grade;When not early warning, maintain normal air pumping state.When hazard occurs, implement grading prevention and control: first grade is intervened by adjusting gas extraction parameter and encrypting detection frequency;Second grade quantitatively injects low-temperature nitrogen into target area and inertizes;Third grade improves nitrogen injection amount of target device while linking adjacent device to assist nitrogen injection, expands inertization range.After hazard is eliminated, restore normal detection and record occurrence position;After device enters deep goaf, new device is re-deployed in working face and historical hazard position information is inherited, and corresponding area is pre-encrypted monitoring.The application greatly improves the pertinence and timeliness of goaf coal spontaneous combustion prevention and control, and ensures coal mine safety production.

Description

Technical Field

[0001] This invention belongs to the field of coal spontaneous combustion prevention and control technology in goaf areas of mines, specifically a device and method for intelligent monitoring and graded prevention and control of coal spontaneous combustion in goaf areas. Background Technology

[0002] Spontaneous combustion of coal in goaf areas is one of the most serious hazards hindering safe coal production in my country. Approximately 56% of coal seams in my country have a tendency to spontaneously combust, resulting in the waste of about 20 million tons of coal annually. Worse still, as coal mining in my country delves deeper, the geothermal gradient increases dramatically, causing more non-spontaneously combustible coal seams to transform into easily combustible ones, further increasing the risk of spontaneous combustion disasters.

[0003] While the integrated top coal caving mining technology has greatly improved mining efficiency, it has also brought about the problem of low top coal recovery rate. A large amount of loose coal remains in the goaf floor, which has good heat storage conditions. If no corresponding prevention and control measures are taken under the effect of air leakage, the coal remains will continue to oxidize and heat up, eventually leading to spontaneous combustion of coal, or even inducing serious accidents such as gas explosions with multiple deaths and injuries.

[0004] Currently, scholars have conducted numerous pilot studies on coal spontaneous combustion monitoring and prevention technologies in goaf areas. Among these, bundled tube monitoring and buried nitrogen injection are the mainstream measures adopted by most mines. Multiple bundled tubes are buried on the intake and return air sides, with daily manual inspections and sampling followed by chromatographic analysis on the ground. The presence of potential coal spontaneous combustion hazards in the goaf is determined based on whether the concentration of indicator gases exceeds the standard. If a hazard is detected, nitrogen is injected through nitrogen injection pipes buried on the intake side in advance for prevention. However, overall, these methods still suffer from fragmentation in coal spontaneous combustion monitoring and prevention, and the nitrogen injection location is often off-center from the potential combustion hazard point, significantly limiting the effectiveness of coal spontaneous combustion monitoring and prevention in goaf areas.

[0005] Therefore, it is necessary to overcome the existing technical deficiencies and propose a new device and method that can simultaneously take into account the intelligent monitoring and prevention of spontaneous combustion of coal in goaf areas, use a graded prevention and control approach to determine the hidden danger area and the level of hidden danger in a very short time, and achieve precise nitrogen injection in the hidden danger area, which greatly ensures the safe production of coal mine working faces. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a method for intelligent monitoring and graded prevention and control of spontaneous combustion of coal in goaf areas. The method employs a device for intelligent monitoring and graded prevention and control of spontaneous combustion of coal in goaf areas, which can simultaneously address both intelligent monitoring and prevention of spontaneous combustion of coal in goaf areas. By adopting a graded prevention and control approach, the method can determine the potential hazard area and its level in a very short time and achieve precise nitrogen injection into the potential hazard area, thereby ensuring safe production at the coal mine working face.

[0007] According to the present invention, a method for intelligent monitoring and graded prevention and control of spontaneous combustion of coal in goaf areas is proposed. The method adopts a device for intelligent monitoring and graded prevention and control of spontaneous combustion of coal in goaf areas. The device includes a three-layer structure: a protective layer, a gas extraction layer, and a core decision layer. The protective layer includes a high-strength porous wear-resistant shell (1), a shock-absorbing spring (4), a high-elasticity silicone (5), and a supporting steel beam (10). The gas extraction layer includes a sampling probe (2), a flange (3), an exhaust pipe (6), a nitrogen injection main pipe (7), a gas delivery pipe (9), a micro negative pressure pump (11), a one-way valve (16), and a nitrogen delivery pipe (17). The control execution layer, namely the core chamber (8), includes an intelligent analyzer (12), a temperature sensor (13), a CO sensor (14), and a C2H2 sensor (15).

[0008] The sampling probe (2) and exhaust pipe (6) each include 8 units, covering the surrounding area of ​​the goaf where the device is located, ensuring full coverage of the gas extraction and nitrogen injection range;

[0009] The sampling probe (2) is connected to the core compartment (8) through the gas delivery pipe (9). The extracted gas passes through the temperature sensor (13), CO sensor (14) and C2H2 sensor (15) in sequence. After being analyzed by the intelligent analyzer (12), the extracted gas is discharged through the exhaust pipe (6) when there is no warning.

[0010] The flange (3) connects the nitrogen injection main pipe (7) and the one-way valve (16). Low-temperature nitrogen enters the gas delivery pipe (9) through the nitrogen injection main pipe (7) and is evenly released to the goaf through the exhaust pipe (6).

[0011] The method includes the following five steps:

[0012] S1: Determine the overall layout and installation of the intelligent monitoring and graded prevention and control system for spontaneous coal combustion:

[0013] After the coal face begins to be mined, three identical intelligent monitoring and graded prevention and control devices for spontaneous combustion of coal are placed behind the hydraulic support, located 20m from the intake air side, in the middle of the working face, and 20m from the return air side, respectively. They are connected in series through nitrogen delivery pipes, with the end of the nitrogen delivery pipes connected to the nitrogen box in the return air roadway. A low-flow nitrogen test injection is performed for 10 minutes to check the airtightness of the device connection.

[0014] S2: Routine vacuum test:

[0015] Set the graded alarm thresholds for the temperature sensor, CO sensor and C2H2 sensor inside the core compartment. After the goaf collapses directly, the micro negative pressure pump will start at a fixed time every day to extract gas from the area near the device through the sampling probe and let it flow through the core compartment to detect whether there is a risk of spontaneous combustion of coal and the level of the risk. After the detection is completed, the gas will be discharged through the exhaust pipe via the gas delivery pipe.

[0016] S3: Classified Prevention and Control of Coal Spontaneous Combustion Hazards:

[0017] When the intelligent analyzer determines that the area where the device is located reaches the level of Class I coal spontaneous combustion risk, it transmits a signal to the ground control center, comprehensively analyzes data such as gas concentration and ventilation volume in the upper corner, and appropriately reduces the extraction negative pressure of the gas extraction measures in the goaf while meeting the requirements for goaf gas control, and increases the frequency of daily gas extraction detection.

[0018] When the intelligent analyzer determines that the area where the device is located reaches the level of Class II coal spontaneous combustion hazard, the one-way valve opens and low-temperature nitrogen is delivered to each device through the nitrogen delivery pipe. After the intelligent analyzer determines the nitrogen injection flow rate, the predetermined flow rate of nitrogen is discharged to the area where the device is located through the exhaust pipe.

[0019] When the intelligent analyzer determines that the area where the device is located has reached the level of Class III coal spontaneous combustion risk, the device increases the nitrogen injection rate, and adjacent devices simultaneously inject nitrogen at a lower flow rate.

[0020] S4: Restore normal air extraction status:

[0021] Once the risk of spontaneous combustion of coal is eliminated, the intelligent analyzer automatically records the location of the device when the risk of spontaneous combustion of coal occurred and transmits it to the ground control center, and resumes the gas extraction and detection at fixed times every day.

[0022] S5: Reinstallation of the intelligent monitoring and graded prevention and control device for spontaneous coal combustion:

[0023] When the device is located 100m deep in the goaf, a second set of intelligent monitoring and graded prevention and control devices for spontaneous combustion of coal is installed at the working face. The location where the spontaneous combustion hazard occurred in the previous set of devices is recorded in the corresponding newly installed device. When the newly installed device approaches the recorded depth of the goaf, even if no spontaneous combustion hazard is detected, the detection frequency is increased. The newly installed series devices repeat steps S1-S4.

[0024] When the device exceeds 100m in depth of the goaf and no new coal spontaneous combustion hazard is detected within 50 days, it indicates that the device has entered the goaf suffocation zone. The connection between the nitrogen delivery pipe and the nitrogen box in the intake airway should be disconnected.

[0025] Furthermore, in step S2, the negative pressure value output by the micro negative pressure pump is -5 to -10 kPa. In the initial stage of detection, a negative pressure of -10 kPa is used to increase the detection range of coal spontaneous combustion hazard in the early stage of low-temperature oxidation of residual coal.

[0026] After the first potential coal spontaneous combustion hazard was detected by the gas sampling device, the negative pressure value was gradually reduced to -5 kPa as the working face advanced, and the gas extraction range was reduced to increase the regional accuracy of coal spontaneous combustion hazard detection.

[0027] Furthermore, in step S3:

[0028] The warning value for Level I hazard is a temperature of 50-70 degrees Celsius or a CO concentration of 0-5 ppm.

[0029] The warning value for a Level II hazard is a temperature between 70 and 100 degrees Celsius or a CO concentration between 5 and 10 ppm.

[0030] The warning threshold for Level III hazards is a temperature greater than 100 degrees Celsius, a CO concentration greater than 10 ppm, or the presence of C2H2 in the test results.

[0031] Furthermore, in step S3, when the intelligent analyzer determines that the area where the device is located reaches the level of Class I coal spontaneous combustion hazard, the frequency of daily gas extraction and detection is increased to 3 times, with a detection interval of 8 hours.

[0032] Furthermore, in step S3, when the intelligent analyzer determines that the area where the device is located reaches the level II coal spontaneous combustion hazard, the expected nitrogen injection flow rate of the target device is 300 m3 / h, and nitrogen is injected into the area around the device without dead angles through 8 exhaust pipes.

[0033] Furthermore, in step S3, when the intelligent analyzer determines that the area where the device is located reaches the level of Class III coal spontaneous combustion hazard, the expected nitrogen injection flow rate of the target device is increased to 500 m3 / h, and the adjacent device simultaneously injects nitrogen at a lower flow rate, with an expected nitrogen injection flow rate of 200 m3 / h.

[0034] Furthermore, in step S3, assuming that the device numbers from the air inlet side to the air return side are 1, 2, and 3 respectively, when device 1 detects that the area where it is located reaches the level III coal spontaneous combustion risk, device 2 will simultaneously inject nitrogen at a lower flow rate.

[0035] When the area detected by Unit 2 reaches the Level III risk of spontaneous combustion of coal, Units 1 and 3 will simultaneously inject nitrogen at a low flow rate.

[0036] When Unit 3 detects that the area has reached a Level III risk of spontaneous combustion of coal, Unit 2 will simultaneously inject nitrogen at a lower flow rate.

[0037] Furthermore, in step S3, when the target device simultaneously detects a Class II coal spontaneous combustion hazard and an adjacent device detects a Class III coal spontaneous combustion hazard, the expected nitrogen injection flow rate is taken as 300 m3 / h.

[0038] Compared with existing technologies, the advantages of the device and method for intelligent monitoring and graded prevention and control of spontaneous combustion of coal in goaf areas disclosed in this invention are as follows:

[0039] (1) This invention realizes the integrated technology of intelligent monitoring and prevention of coal spontaneous combustion, which solves the problems of the separation and response lag of traditional coal spontaneous combustion monitoring and prevention methods, and greatly improves the risk identification capability of hidden danger areas.

[0040] (2) The present invention adopts a graded prevention and control method to achieve accurate identification of hidden danger areas and hidden danger levels, and adopts different targeted measures for different hidden danger levels, thereby achieving accurate nitrogen injection in hidden danger areas and solving the problems of resource waste and poor prevention and control effect caused by blind nitrogen injection. Attached Figure Description

[0041] To make the objectives, methods, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the drawings described below are merely some practical examples of this invention. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort. In particular:

[0042] Figure 1 This is a schematic flowchart of an intelligent monitoring and graded prevention and control device and method for spontaneous combustion of coal in goaf areas disclosed in an embodiment of the present invention.

[0043] Figure 2 This is a schematic cross-sectional view of an intelligent monitoring and graded prevention and control device for spontaneous combustion of coal in goaf areas, as disclosed in an embodiment of the present invention.

[0044] Figure 3 This is a cross-sectional structural diagram of the core compartment of a device for intelligent monitoring and graded prevention and control of spontaneous combustion of coal in goaf areas, as disclosed in an embodiment of the present invention.

[0045] Figure 4 This is a schematic diagram of the overall layout of a device for intelligent monitoring and graded prevention and control of spontaneous combustion of coal in goaf areas, as disclosed in an embodiment of the present invention.

[0046] Figures 2 to 4 The numbers in the text represent the component names as follows:

[0047] 1-High-strength porous wear-resistant shell; 2-Sampling probe; 3-Flange; 4-Shock-absorbing spring; 5-High-elasticity silicone; 6-Exhaust pipe; 7-Nitrogen injection main pipe; 8-Core compartment; 9-Gas delivery pipe; 10-Supporting steel beam; 11-Miniature negative pressure pump; 12-Intelligent analyzer; 13-Temperature sensor; 14-CO sensor; 15-C2H2 sensor; 16-One-way valve; 17-Nitrogen delivery pipe. Detailed Implementation

[0048] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. These preferred embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0049] Figure 1This is a schematic flowchart of an intelligent monitoring and graded prevention and control device and method for spontaneous combustion of coal in goaf areas disclosed in an embodiment of the present invention. Figure 2 This is a schematic cross-sectional view of an intelligent monitoring and graded prevention and control device for spontaneous combustion of coal in goaf areas disclosed in an embodiment of the present invention. Figure 3 This is a cross-sectional structural diagram of the core compartment of a device for intelligent monitoring and graded prevention and control of spontaneous combustion of coal in goaf areas, as disclosed in an embodiment of the present invention. Figure 4 This is a schematic diagram of the overall layout of a device for intelligent monitoring and graded prevention of spontaneous combustion of coal in goaf areas, as disclosed in an embodiment of the present invention. The device and method for intelligent monitoring and graded prevention of spontaneous combustion of coal in goaf areas disclosed in this invention specifically include the following five steps:

[0050] S1: Determine the overall layout and installation of the intelligent monitoring and graded prevention and control system for spontaneous coal combustion:

[0051] After the coal mining face begins to be mined, three identical intelligent monitoring and graded control devices for spontaneous combustion of coal are first assembled on the ground. The sensitivity and accuracy of the temperature sensor (13), CO sensor (14) and C2H2 sensor (15) in the core chamber (8) are calibrated by test pumping. Then the devices are brought into the underground working face and placed behind the hydraulic support, located 20m from the air intake side, in the middle of the working face and 20m from the air return side, respectively. They are connected in series by nitrogen delivery pipe (17). The end of the nitrogen delivery pipe (17) is connected to the nitrogen box in the air return roadway. One-way valve (16) is connected to the end of each device near the air intake side. Its opening and closing are controlled by the intelligent analyzer (12) in the core chamber (8). After the devices are arranged, the power supply of the three devices is turned on and nitrogen is injected at a low flow rate for 10 minutes to check the airtightness of the device connection.

[0052] S2: Routine vacuum test:

[0053] Set the graded alarm thresholds for the internal temperature sensor (13), CO sensor (14) and C2H2 sensor (15) of the core compartment (8). After the direct collapse of the goaf, the micro negative pressure pump (11) is started during a fixed time period every day. The gas is extracted from the area near the device through the sampling probe (2) and flows through the core compartment (8) to detect whether there is a risk of spontaneous combustion of coal and the level of the risk. After the detection is completed, the gas is discharged through the gas delivery pipe (9) and the exhaust pipe (6).

[0054] The negative pressure value output by the micro negative pressure pump (11) is -5 to -10KPa. In the early stage of detection, a negative pressure of -10KPa is used. In the early stage of low-temperature oxidation of residual coal, the detection range of coal spontaneous combustion hazard is increased. After the first coal spontaneous combustion hazard appears in the gas sampling detection of the device, the negative pressure value is gradually reduced to -5KPa as the working face advances, and the gas extraction range is reduced to increase the regional accuracy of coal spontaneous combustion hazard detection.

[0055] S3: Classified Prevention and Control of Coal Spontaneous Combustion Hazards:

[0056] The warning value for a Level I hazard is a temperature of 50-70 degrees or a CO concentration of 0-5 ppm. When the intelligent analyzer (12) determines that the area where the device is located reaches a Level I coal spontaneous combustion hazard, it transmits a signal to the ground control center, comprehensively analyzes data such as gas concentration and ventilation volume in the upper corner, and appropriately reduces the negative pressure of gas extraction measures in the goaf area under the premise of meeting the requirements for gas control in the goaf area, and increases the frequency of daily gas extraction detection to 3 times, with a detection interval of 8 hours.

[0057] The warning value for a Level II hazard is a temperature of 70-100 degrees Celsius or a CO concentration of 5-10 ppm. When the intelligent analyzer (12) determines that the area where the device is located reaches a Level II coal spontaneous combustion hazard, the one-way valve (16) opens, and low-temperature nitrogen is supplied to each device through the nitrogen delivery pipe (17). The expected nitrogen injection flow rate of the target device is 300 m³ / s. 3 / h, nitrogen is injected into the area around the device without dead angles through 8 exhaust pipes (6).

[0058] The warning value for a Level III hazard is a temperature greater than 100 degrees Celsius, a CO concentration greater than 10 ppm, or the presence of C2H2 in the test. When the intelligent analyzer (12) determines that the area where the device is located has reached a Level III coal spontaneous combustion hazard, the device increases the nitrogen injection rate, and adjacent devices simultaneously inject nitrogen at a lower flow rate. The expected nitrogen injection flow rate of the target device is increased to 500 m³ / h. 3 / h, the expected nitrogen injection flow rate of the adjacent unit is 200m³ / h. 3 / h, when the target unit simultaneously detects a Class II coal spontaneous combustion hazard and the adjacent unit detects a Class III coal spontaneous combustion hazard, its expected nitrogen injection flow rate is taken as 300m³ / h. 3 / h.

[0059] Assuming the devices from the air inlet side to the air outlet side are numbered 1, 2, and 3 respectively, when device 1 detects that the area it is in reaches a Level III coal spontaneous combustion hazard, device 2 will simultaneously inject nitrogen at a lower flow rate. When device 2 detects that the area it is in reaches a Level III coal spontaneous combustion hazard, devices 1 and 3 will simultaneously inject nitrogen at a lower flow rate. When device 3 detects that the area it is in reaches a Level III coal spontaneous combustion hazard, device 2 will simultaneously inject nitrogen at a lower flow rate.

[0060] S4: Restore normal air extraction status:

[0061] Once the risk of spontaneous combustion of coal is eliminated, the intelligent analyzer (12) automatically records the location of the device when the risk of spontaneous combustion of coal occurs and transmits it to the ground control center, and resumes the daily fixed time period for gas extraction detection.

[0062] S5: Reinstallation of the intelligent monitoring and graded prevention and control device for spontaneous coal combustion:

[0063] When the device is located 100m deep in the goaf, a second set of intelligent monitoring and graded prevention and control devices for spontaneous combustion of coal is installed at the working face. The location where the spontaneous combustion hazard occurred in the previous set of devices is recorded in the corresponding newly installed device. When the newly installed device approaches the recorded depth of the goaf, even if no spontaneous combustion hazard is detected, the detection frequency is increased to 3 times, with a detection interval of 8 hours. The newly installed series devices repeat steps S1-S4.

[0064] When the device exceeds 100m in depth of the goaf and no new coal spontaneous combustion hazard is detected within 50 days, it indicates that the device has entered the goaf suffocation zone. The connection between the nitrogen delivery pipe and the nitrogen box in the intake airway should be disconnected.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the method of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the method described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding method to deviate from the scope defined by the claims of the present invention.

Claims

1. A method for intelligent monitoring and graded prevention and control of spontaneous combustion of coal in goaf, using a device for intelligent monitoring and graded prevention and control of spontaneous combustion of coal in goaf, the device comprising a three-layer structure of a protective layer, a gas extraction layer and a core decision layer, the protective layer comprising a high-strength porous wear-resistant shell (1), a shock-absorbing spring (4), a high-elasticity silicone (5) and a supporting steel beam (10), the gas extraction layer comprising a sampling probe (2), a flange (3), an exhaust pipe (6), a nitrogen injection main pipe (7), a gas delivery pipe (9), a micro negative pressure pump (11), a one-way valve (16) and a nitrogen delivery pipe (17), the core decision layer being the core chamber (8), comprising an intelligent analyzer (12), a temperature sensor (13), a CO sensor (14) and a C2H2 sensor (15); The sampling probe (2) and exhaust pipe (6) each include 8 units, covering the surrounding area of ​​the goaf where the device is located, ensuring full coverage of the gas extraction and nitrogen injection range; The sampling probe (2) is connected to the core compartment (8) through the gas delivery pipe (9). The extracted gas passes through the temperature sensor (13), CO sensor (14) and C2H2 sensor (15) in sequence. After being analyzed by the intelligent analyzer (12), the extracted gas is discharged through the exhaust pipe (6) when there is no warning. The flange (3) connects the nitrogen injection main pipe (7) and the one-way valve (16). Low-temperature nitrogen enters the gas delivery pipe (9) through the nitrogen injection main pipe (7) and is evenly released to the goaf through the exhaust pipe (6). The method includes the following five steps: S1: Determine the overall layout and installation of the intelligent monitoring and graded prevention and control system for spontaneous coal combustion: After the coal face begins to be mined, three identical intelligent monitoring and graded prevention and control devices for spontaneous combustion of coal are placed behind the hydraulic support, located 20m from the intake air side, in the middle of the working face, and 20m from the return air side, respectively. They are connected in series through nitrogen delivery pipes, with the end of the nitrogen delivery pipes connected to the nitrogen box in the return air roadway. A low-flow nitrogen test injection is performed for 10 minutes to check the airtightness of the device connection. S2: Routine vacuum test: Set the graded alarm thresholds for the temperature sensor, CO sensor and C2H2 sensor inside the core compartment. After the goaf collapses directly, the micro negative pressure pump will start at a fixed time every day to extract gas from the area near the device through the sampling probe and let it flow through the core compartment to detect whether there is a risk of spontaneous combustion of coal and the level of the risk. After the detection is completed, the gas will be discharged through the exhaust pipe via the gas delivery pipe. S3: Classified Prevention and Control of Coal Spontaneous Combustion Hazards: When the intelligent analyzer determines that the area where the device is located reaches the level of Class I coal spontaneous combustion risk, it transmits a signal to the ground control center, comprehensively analyzes the gas concentration and ventilation data in the upper corner, and appropriately reduces the extraction negative pressure of the gas extraction measures in the goaf while meeting the requirements for goaf gas control, and increases the frequency of daily gas extraction detection. When the intelligent analyzer determines that the area where the device is located reaches a Level II coal spontaneous combustion hazard, the one-way valve opens, and cryogenic nitrogen is supplied to each device through the nitrogen delivery pipe. The expected nitrogen injection flow rate for the target device is 300m³. 3 / h, nitrogen is injected into the surrounding area of ​​the device through 8 exhaust pipes without any blind spots; When the intelligent analyzer determines that the area where the device is located reaches a Level III risk of spontaneous combustion of coal, the expected nitrogen injection flow rate of the target device is increased to 500 m³ / h. 3 / h, adjacent units synchronously inject nitrogen at a lower flow rate, with an expected nitrogen injection flow rate of 200m³ / h. 3 / h; S4: Restore normal air extraction status: Once the risk of spontaneous combustion of coal is eliminated, the intelligent analyzer automatically records the location of the device when the risk of spontaneous combustion of coal occurred and transmits it to the ground control center, and resumes the gas extraction and detection at fixed times every day. S5: Reinstallation of the intelligent monitoring and graded prevention and control device for spontaneous combustion of coal: When the device is located 100m deep in the goaf, a second set of intelligent monitoring and graded prevention and control devices for spontaneous combustion of coal is installed at the working face. The location where the spontaneous combustion hazard occurred in the previous set of devices is recorded in the corresponding newly installed device. When the newly installed device approaches the recorded depth of the goaf, even if no spontaneous combustion hazard is detected, the detection frequency is increased. The newly installed series devices repeat steps S1-S4. When the device exceeds 100m in depth of the goaf and no new coal spontaneous combustion hazard is detected within 50 days, it indicates that the device has entered the goaf suffocation zone. The connection between the nitrogen delivery pipe and the nitrogen box in the intake airway should be disconnected.

2. The method for intelligent monitoring and graded prevention and control of spontaneous combustion of coal in goaf areas as described in claim 1, characterized in that, In step S2, the negative pressure output by the micro negative pressure pump is -5 to -10 kPa. In the initial stage of detection, a negative pressure of -10 kPa is used to increase the detection range of coal spontaneous combustion hazards in the early stage of low-temperature oxidation of residual coal. After the first potential coal spontaneous combustion hazard was detected by the gas sampling device, the negative pressure value was gradually reduced to -5 kPa as the working face advanced, and the gas extraction range was reduced to increase the regional accuracy of coal spontaneous combustion hazard detection.

3. The method for intelligent monitoring and graded prevention and control of spontaneous combustion of coal in goaf areas as described in claim 1, characterized in that, In step S3: The warning value for Level I hazard is a temperature of 50-70 degrees Celsius or a CO concentration of 0-5 ppm. The warning value for a Level II hazard is a temperature between 70 and 100 degrees Celsius or a CO concentration between 5 and 10 ppm. The warning threshold for Level III hazards is a temperature greater than 100 degrees Celsius, a CO concentration greater than 10 ppm, or the presence of C2H2 in the test results.

4. The method for intelligent monitoring and graded prevention and control of spontaneous combustion of coal in goaf areas as described in claim 1, characterized in that, In step S3, when the intelligent analyzer determines that the area where the device is located reaches the level of Class I coal spontaneous combustion hazard, the frequency of daily gas extraction and detection is increased to 3 times, with a detection interval of 8 hours.

5. The method for intelligent monitoring and graded prevention and control of spontaneous combustion of coal in goaf areas as described in claim 1, characterized in that, In step S3, assuming that the device numbers from the air inlet side to the air return side are 1, 2, and 3 respectively, when device 1 detects that the area where it is located reaches the level III coal spontaneous combustion risk, device 2 will simultaneously inject nitrogen at a lower flow rate. When the area detected by Unit 2 reaches the Level III risk of spontaneous combustion of coal, Units 1 and 3 will simultaneously inject nitrogen at a low flow rate. When Unit 3 detects that the area has reached a Level III risk of spontaneous combustion of coal, Unit 2 will simultaneously inject nitrogen at a lower flow rate.

6. The method for intelligent monitoring and graded prevention and control of spontaneous combustion of coal in goaf areas as described in claim 1, characterized in that, In step S3, when the target device simultaneously detects a Class II coal spontaneous combustion hazard and an adjacent device detects a Class III coal spontaneous combustion hazard, the expected nitrogen injection flow rate is taken as 300m³. 3 / h.

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