A method for monitoring and preventing spontaneous combustion in a coal mine goaf

Abstract

This invention discloses a method for monitoring and preventing spontaneous combustion in coal mine goaf areas, comprising the following steps: 1) selecting monitoring points; 2) arranging monitoring points; 3) data monitoring; 4) spontaneous combustion prevention; and 5) analyzing the prevention effect. Using bottom-layer boreholes as monitoring points, monitoring pipes, control pipes, grouting pipes, and slurry discharge pipes are arranged at the monitoring points. Sampling pipes and cables are arranged inside the monitoring pipes, and temperature probes are installed at the ends of the cables. The boreholes are sealed using the grouting and slurry discharge pipes. The gas composition, concentration, and temperature data at each monitoring point are monitored through the monitoring pipes to determine the spontaneous combustion hazard area in the goaf. Then, targeted spontaneous combustion prevention is carried out through grouting or inert injection via the control pipes. The monitoring pipes are used to analyze the effect of the remediation on spontaneous combustion prevention. This method achieves accurate detection and point-to-point remediation of spontaneous combustion hazard areas in goaf areas, as well as the multi-purpose function of a single borehole for "monitoring-remediation-monitoring," which helps ensure safe and efficient coal mining.

Description

Technical Field

[0001] This invention belongs to the field of monitoring and prevention of spontaneous combustion of coal residue in goaf areas, and specifically relates to a method for monitoring and prevention of spontaneous combustion in coal mine goaf areas. Background Technology

[0002] Coal, as a vital strategic resource for my country, is the foundation of the country's energy security and will continue to dominate my country's energy consumption for a considerable period. With the rapid development of coal mining technology, coal mine production is becoming increasingly efficient and intensive, with more and more high-face mining operations. While this has significantly improved production efficiency, it has also created problems such as severe air leakage in goafs and large amounts of residual coal, providing conditions for spontaneous combustion of coal in goafs. Furthermore, as mining depth increases, the rising temperature of the original rock makes the coal more susceptible to oxidation, further increasing the risk of spontaneous combustion of residual coal in goafs.

[0003] However, due to the complex conditions of the goaf itself, direct observation of its interior is impossible. Furthermore, the concealment of ignition sources within the goaf makes accurate prediction and forecasting of spontaneous combustion of residual coal a significant challenge. Currently, coal mining enterprises commonly employ bundled tube monitoring systems installed in the roadways at both ends of the working face. These systems analyze the gas composition within the goaf to determine the likelihood of spontaneous combustion and delineate "three zones of spontaneous combustion." However, existing bundled tube monitoring systems have revealed numerous defects and shortcomings in practical use. For example, this method can only detect two areas of the goaf (machine duct and ventilation duct) and cannot monitor the internal conditions of the goaf. It cannot accurately and quickly determine the location of the ignition. Moreover, the complex internal environment of the goaf, with collapsed roof rock easily damaging the bundled tube probes, prevents the monitoring system from detecting spontaneous combustion and implementing fire prevention and extinguishing measures in a timely manner, resulting in low efficiency in goaf spontaneous combustion prevention. How to accurately detect the hazardous areas of spontaneous combustion in the goaf and conduct targeted fire prevention remains a key focus and challenge in on-site fire prevention and extinguishing work. Summary of the Invention

[0004] This invention addresses the need for spontaneous combustion prevention in goaf areas and the shortcomings of existing methods for monitoring spontaneous combustion hazard areas in goaf areas. It provides a method for monitoring and preventing spontaneous combustion in coal mine goaf areas, enabling accurate detection of spontaneous combustion hazard areas in coal seam goaf areas, and allowing for targeted, point-to-point prevention and control measures such as inert injection and grouting to improve the efficiency of spontaneous combustion monitoring and prevention.

[0005] To achieve the above objectives, the present invention provides a method for monitoring and preventing spontaneous combustion in coal mine goaf areas, the specific steps of which are as follows:

[0006] 1) Layout of measuring points: Densely arrange floor penetration boreholes in key areas such as mining line, stop mining line, intake airway and return airway (two lines and two channels), and sparsely arrange floor penetration boreholes inside the goaf.

[0007] 2) Installation of measuring points: Monitoring pipes, control pipes, grouting pipes and grout discharge pipes are installed in each through-layer borehole of the base plate;

[0008] 3) Data monitoring: Gases in the goaf are collected through sampling tubes and their components and concentrations are measured. The concentrations of gases such as O2, CO, C2H4, CH4, CO2, and C2H2 at different measuring points are analyzed. Combined with the temperature data of the goaf monitored by temperature probes, the spontaneous combustion hazard zone in the goaf is determined.

[0009] 4) Spontaneous combustion prevention: By injecting grout or inert gases such as nitrogen and carbon dioxide into the goaf through the control pipe, the risk of spontaneous combustion in the goaf is controlled.

[0010] 5) Analysis of prevention and control effect: After taking spontaneous combustion prevention and control measures, continue to monitor the gas composition, gas concentration and temperature of the spontaneous combustion hazard area in the goaf, and analyze the spontaneous combustion prevention and control effect. If the area still has a spontaneous combustion hazard, repeat step 4) until the residual coal in the goaf enters the asphyxiation zone with the advancement of the working face, that is, the O2 concentration in the goaf is <8%, and stop the data monitoring and spontaneous combustion prevention and control in this area.

[0011] Furthermore, in step 2), ball valves are installed outside the perforation borehole in the bottom slab for the measure pipe, grouting pipe, grout discharge pipe, and sampling pipe.

[0012] Furthermore, in step 2), a perforated tube is provided at the end of the monitoring tube, and the perforated tube and the monitoring tube are connected by threads, and the perforated tube and the monitoring tube are sealed with polyurethane.

[0013] Furthermore, in step 2), the grouting pipe is connected in sequence from the orifice to the front bladder, the middle bladder and the rear bladder, with the rear bladder close to the perforated pipe. A one-way valve is provided at the part of the grouting pipe that connects to the front bladder, the middle bladder and the rear bladder, and a burst valve is provided at the part of the grouting pipe located between the front bladder and the middle bladder.

[0014] Furthermore, in step 2), the monitoring pipe, the measure pipe, the grouting pipe, and the grout discharge pipe are fixed in the borehole by a "three-blocking and one-grouting" sealing method, that is, grouting is performed between the front bladder and the middle bladder to form an effective sealing section, and no grouting is performed between the middle bladder and the rear bladder.

[0015] Furthermore, in step 2), the discharge pipe passes through the outer bladder bag, with the discharge pipe opening close to the middle bladder bag.

[0016] Furthermore, in step 2), the temperature probe is a copper tube that is closed at one end and open at the other. A temperature sensor is installed inside the copper tube. The temperature sensor is connected to a cable inside the monitoring tube, and the opening of the temperature probe is sealed with epoxy resin.

[0017] Furthermore, in step 2), the sampling tube, monitoring tube, slurry discharge tube, and perforated tube are made of PVC pipe, and the measure tube and grouting tube are made of pressure-resistant flexible hose.

[0018] Furthermore, in step 2), the sampling tube can be used for both slurry discharge and drainage.

[0019] The present invention has the following beneficial effects:

[0020] A. This invention utilizes the bottom plate through-layer drilling as a protective structure to arrange spontaneous combustion monitoring pipes in the goaf, which not only reduces construction costs but also reduces the risk of roof collapse rocks damaging the monitoring pipes, thereby improving the reliability and effectiveness of the device.

[0021] B. The "three-blocking and one-injection" sealing method is adopted. On the one hand, an effective sealing section is formed by grouting between the front and middle bags to ensure the sealing effect of the borehole. On the other hand, due to the large space inside the borehole, in order to ensure that the gas sample collected by the sampling tube comes from the goaf, the rear bag is arranged on the side close to the flower tube to ensure the reliability of gas sample collection.

[0022] C. By monitoring the gas composition, concentration, and temperature data at each measuring point through the monitoring tube, the spontaneous combustion situation inside the goaf can be monitored, and the spontaneous combustion hazard area in the goaf can be accurately detected;

[0023] D. Using the bottom plate through-layer boreholes as measuring points, the measuring points are densely arranged in the mining line, the stop mining line, the intake airway and the return airway (two lines and two channels), and sparsely arranged in the goaf area, realizing the spontaneous combustion monitoring function in the goaf area.

[0024] E. By deploying monitoring pipes to accurately detect spontaneous combustion hazard areas in goafs, and then using grouting or inert injection measures through the control pipes to carry out targeted spontaneous combustion prevention and control, and using the monitoring pipes to analyze the effect of spontaneous combustion prevention and control after treatment, point-to-point treatment of spontaneous combustion hazard areas within goafs, the dual function of grouting or inert injection of control pipes, and the multi-purpose function of a borehole for "monitoring-treatment-monitoring" are realized, which helps to ensure safe and efficient mining of coal mines. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the present invention;

[0026] Figure 2 for Figure 1 Schematic diagram of the central flower tube section;

[0027] Figure 3 This is a radial cross-sectional view of the measuring point arrangement of the present invention;

[0028] Among them, 1-bottom plate through-layer drilling, 2-flower pipe, 3-temperature probe, 4-polyurethane, 5-sampling tube, 6-rear bladder, 7-middle bladder, 8-front bladder, 9-monitoring tube, 10-cable, 11-ball valve, 12-grout discharge pipe, 13-grouting pipe, 14-burst valve, 15-one-way valve, 16-epoxy resin, 17-temperature sensor, 18-measurement pipe. Detailed Implementation

[0029] 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. 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.

[0030] Combination Figures 1-3 As shown, a method for monitoring and preventing spontaneous combustion in coal mine goaf includes the following steps:

[0031] 1) Layout of measuring points: Densely arrange floor penetration boreholes 1 in key areas such as mining line, stop mining line, intake airway and return airway (two lines and two channels), and sparsely arrange floor penetration boreholes 1 in the goaf.

[0032] 2) Installation of measuring points: A monitoring pipe 9, a measure pipe 18, a grouting pipe 13 and a grout discharge pipe 12 are arranged in each bottom slab through-layer drilling hole 1. A sampling pipe 5 and a cable 10 are arranged in the monitoring pipe 9. A temperature probe 3 is connected to the end of the cable 10.

[0033] 3) Data monitoring: The gas in the goaf is collected through sampling tube 5 and the gas composition and concentration are measured. The concentration distribution of O2, CO, C2H4, CH4, CO2 and C2H2 gas at different measuring points is analyzed. Combined with the goaf temperature data monitored by temperature probe 3, the goaf spontaneous combustion hazard area is determined.

[0034] 4) Spontaneous combustion prevention: After identifying the spontaneous combustion hazard area in the goaf, grout or inert gases such as nitrogen and carbon dioxide are injected into the goaf through the measures pipe 18 to treat the spontaneous combustion hazard area in the goaf.

[0035] 5) Analysis of prevention and control effect: After taking spontaneous combustion prevention and control measures, continue to monitor the gas composition, gas concentration and temperature of the spontaneous combustion hazard area in the goaf, and analyze the spontaneous combustion prevention and control effect. If the area still has a spontaneous combustion hazard, repeat step 4) until the residual coal in the goaf enters the asphyxiation zone with the advancement of the working face, that is, the O2 concentration in the goaf is <8%, and stop the data monitoring and spontaneous combustion prevention and control in this area.

[0036] In step 2), the sampling pipe 5, monitoring pipe 9, slurry discharge pipe 12, and perforated pipe 2 are made of PVC pipe, while the measure pipe 18 and grouting pipe 13 are made of pressure-resistant flexible hose. Ball valves 11 are installed on the outside of the bottom slab through-hole 1 of the sampling pipe 5, grouting pipe 13, and slurry discharge pipe 12 to control the opening and closing of these pipes. Simultaneously, controlling the opening and closing of the ball valve 11 on the sampling pipe 5 also enables the discharge of water accumulation in the bottom slab through-hole 1 and residual slurry from the bottom slab through-hole 1 after grouting in the goaf. The monitoring tube 9 contains a sampling tube 5 and a cable 10. A temperature probe 3 is connected to the end of the cable 10. The temperature probe 3 is a copper tube with one closed end and one open end. A temperature sensor 17 is installed inside the copper tube to monitor the temperature data of the goaf. The temperature sensor 17 is connected to the cable 10 inside the monitoring tube 9, and the opening of the temperature probe 3 is sealed with epoxy resin 16 to prevent water accumulation and damage to the temperature sensor 17 due to water seepage in the bottom plate perforation borehole 1. A perforated tube 2 is installed at the end of the monitoring tube 9. The perforated tube 2 and the monitoring tube 9 are connected by threads, and polyurethane 4 is filled between the perforated tube 2 and the monitoring tube 9. This serves two purposes: firstly, to fix the sampling tube 5 and the cable 10, and secondly, to prevent the monitoring tube 9 from communicating with the atmosphere, ensuring that the collected gas sample originates from the goaf. The grouting pipe 13 is connected sequentially from the orifice to a front bladder 8, a middle bladder 7, and a rear bladder 6. The monitoring pipe 9, grouting pipe 13, and grout discharge pipe 12 are fixed inside the bottom slab through-layer borehole 1 using a "three-plug-one-injection" sealing method. A one-way valve 15 is installed at the connection point of the grouting pipe 13 with the front bladder 8, middle bladder 7, and rear bladder 6 to inject grout into the bladders, preventing grout backflow and ensuring effective sealing of the bottom slab through-layer borehole 1. A one-way valve 15 is installed at the portion of the grouting pipe 13 between the front bladder 8 and the middle bladder 7. A burst valve 14 is provided. When the pressure of the grouting pipe 13 reaches the activation pressure of the burst valve 14, the grout is injected into the borehole space between the front bladder 8 and the middle bladder 7 by the burst valve 14, forming an effective sealing section. No grouting is performed between the middle bladder 7 and the rear bladder 6. Since the internal space of the bottom plate through-layer borehole 1 is relatively large, in order to avoid the gas collected by the sampling pipe 5 coming from the bottom plate through-layer borehole 1 and affecting the monitoring of the actual spontaneous combustion state inside the goaf, the rear bladder 6 should be arranged as close as possible to the perforated pipe 2. The grout discharge pipe 12 passes through the outer bladder, and the opening of the grout discharge pipe 12 is close to the side of the middle bladder 7. When the grout enters the sealing section through the burst valve 14, the gas in the sealing section is discharged through the grout discharge pipe 12. When the grout flows out of the grout discharge pipe 12, the grouting stops.

[0037] During the installation of the measuring point, after assembling and connecting the monitoring pipe 9, the measure pipe 18, the grouting pipe 13, and the grout discharge pipe 12, the monitoring pipe 9 is inserted into the bottom slab through-layer borehole 1. The monitoring pipe 9 is placed as close as possible to the upper end of the bottom slab through-layer borehole 1, but it should not extend beyond the bottom slab through-layer borehole 1. The ball valve 11 on the grouting pipe 13 is opened, and grout is injected into the front bladder 8, the middle bladder 7, and the rear bladder 6 through the one-way valve 15 on the grouting pipe 13, causing the bladders to expand rapidly. This tightens the outer diameter of the front bladder 8, the middle bladder 7, and the rear bladder 6 to the borehole wall, and at the same time, it also serves to fix the monitoring pipe 9, the grouting pipe 13, and the grout discharge pipe 12. Continuous injection of grout causes the pressure in the grouting pipe 13 to gradually increase. When the pressure exceeds the activation pressure of the rupture valve 14, the rupture valve 14 opens, and the grout is injected through the borehole space between the front bag 8 and the middle bag 7 to form an effective sealing section. During the grouting process into the sealing section, the ball valve 11 on the grout discharge pipe 12 is opened to discharge the air in the sealing section. Grout is stopped when grout flows out of the grout discharge pipe 12 and the ball valve 11 on the grout discharge pipe 12 and the grouting pipe 13 are closed. After the sealing is completed, the gas inside the goaf is extracted through the sampling pipe 5 for analysis. Combined with the temperature data collected by the temperature sensor 17, the spontaneous combustion hazard area of ​​the goaf is determined, realizing the goaf spontaneous combustion monitoring function. Then, the spontaneous combustion hazard area of ​​the goaf is treated by injecting grout or inert gases such as nitrogen and carbon dioxide into the goaf through the measure pipe 18, realizing the dual function of grouting and inert gas injection of the measure pipe 18.

[0038] The embodiments described above are only for illustrating the present invention and are not intended to limit the scope of application of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for monitoring and preventing spontaneous combustion in a coal mine goaf, characterized in that, Includes the following steps: 1) Layout of measuring points: Densely arrange floor penetration boreholes (1) in the mining line, stop mining line, intake airway and return airway area, and sparsely arrange floor penetration boreholes (1) inside the goaf. 2) Installation of measuring points: A monitoring pipe (9), a measure pipe (18), a grouting pipe (13), and a grout discharge pipe (12) are arranged in each through-layer borehole (1) of the base plate. A sampling pipe (5) and a cable (10) are arranged in the monitoring pipe (9). A temperature probe (3) is connected to the end of the cable (10). A perforated pipe (2) is provided at the end of the monitoring pipe (9). The perforated pipe (2) and the monitoring pipe (9) are connected by threads. The perforated pipe (2) and the monitoring pipe (9) are sealed with polyurethane (4). The grouting pipe (13) is connected sequentially from the borehole opening inward. There are a front grouting bag (8), a middle grouting bag (7), and a rear grouting bag (6). The rear grouting bag (6) is close to the perforated pipe (2). The part of the grouting pipe (13) connected to the front grouting bag (8), the middle grouting bag (7), and the rear grouting bag (6) is equipped with a one-way valve (15) for injecting grout into the grouting bag to prevent grout backflow from causing poor sealing of the bottom plate through-layer borehole (1). The part of the grouting pipe (13) located between the front grouting bag (8) and the middle grouting bag (7) is equipped with a burst valve (14). The monitoring pipe (9), the measure pipe (18), the grouting pipe (13), and the grout discharge pipe (1) are all equipped with a one-way valve (15) for injecting grout into the grouting bag to prevent grout backflow from causing poor sealing of the bottom plate through-layer borehole (1). 2) The grout is fixed in the bottom plate through-layer borehole (1) by the "three-blocking and one-injection" sealing method, that is, grouting is performed between the front bladder (8) and the middle bladder (7), and no grouting is performed between the middle bladder (7) and the rear bladder (6); grout is injected into the front bladder (8), the middle bladder (7) and the rear bladder (6) through the one-way valve (15) on the grouting pipe (13) to make the bladders expand rapidly; continuous injection of grout causes the pressure of the grouting pipe (13) to gradually increase. When the pressure is greater than the starting pressure of the burst valve (14), the burst valve (14) opens, and the grout will pass through the front bladder. Grouting is performed in the borehole space between (8) and the middle bag (7) to form an effective sealing section; the outer diameters of the front bag (8), the middle bag (7) and the rear bag (6) are fastened to the borehole wall, which also serves to fix the monitoring pipe (9), the grouting pipe (13) and the grout discharge pipe (12); ball valves (11) are installed on the measure pipe (18), the grouting pipe (13), the grout discharge pipe (12) and the sampling pipe (5) outside the bottom plate through-layer borehole (1); the grout discharge pipe (12) passes through the outer bag, and the opening of the grout discharge pipe (12) is close to the middle bag (7); 3) Data monitoring: The gas in the goaf is collected by sampling tube (5) and the gas composition and concentration are measured. The concentrations of O2, CO, C2H4, CH4, CO2 and C2H2 at different measuring points are analyzed. Combined with the goaf temperature data monitored by temperature probe (3), the goaf spontaneous combustion hazard area is determined. 4) Spontaneous combustion prevention: Grouting or nitrogen and carbon dioxide inert gas are injected into the goaf through the measure pipe (18) to treat the spontaneous combustion hazard area of ​​the goaf; 5) Analysis of prevention and control effect: After taking measures to prevent spontaneous combustion in the goaf, continue to monitor the gas composition, gas concentration and temperature of the goaf area with spontaneous combustion risk, and analyze the effect of spontaneous combustion prevention and control. If there is still a risk of spontaneous combustion in the above areas, repeat step 4) until the residual coal in the goaf enters the asphyxiation zone with the advancement of the working face, that is, the O2 concentration in the goaf is <8%, and stop the data monitoring and spontaneous combustion prevention and control in this area.

2. The method for monitoring and preventing spontaneous combustion in coal mine goafs according to claim 1, characterized in that, In step 2), the temperature probe (3) is a copper tube that is closed at one end and open at the other end. A temperature sensor (17) is installed inside the copper tube. The temperature sensor (17) is connected to the cable (10) inside the monitoring tube (9), and the opening of the temperature probe (3) is sealed with epoxy resin (16).

3. The method for monitoring and preventing spontaneous combustion in coal mine goafs according to claim 1, characterized in that, In step 2), the sampling tube (5), monitoring tube (9), slurry discharge tube (12) and flower tube (2) are made of PVC pipe, and the measure tube (18) and grouting tube (13) are made of pressure-resistant hose.

4. The coal mine goaf spontaneous combustion monitoring and prevention method according to claim 1, characterized in that, In step 2), the sampling tube (5) is used for both slurry discharge and drainage.

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