Coal spontaneous combustion early warning device and method through CO graded concentration

Abstract

The present invention provides a coal spontaneous combustion early warning device through graded CO concentration, comprising a primary compression chamber, a secondary compression chamber, a gas detection chamber, an intelligent central control system, an air inlet pipeline, a first air outlet pipeline, a second air outlet pipeline, and a third air outlet pipeline. The air inlet of the primary compression chamber is connected to the air inlet pipeline, and the air outlet of the primary compression chamber is connected to the air inlet of the secondary compression chamber via the first air outlet pipeline. The present invention also provides a coal spontaneous combustion early warning method through graded CO concentration. By adopting a two-step adsorbent pressure swing adsorption method in the primary and secondary compression chambers, the present invention improves the detection accuracy of low-concentration CO gas concentration and achieves efficient monitoring of low-concentration CO gas. The present invention is applicable to the complex environment of underground goafs. The present invention provides effective measures and methods for predicting coal spontaneous combustion in underground goafs through graded early warning.

Description

Technical Field

[0001] The present invention relates to the technical field of low-temperature coal oxidation monitoring in coal mine goafs. In particular, it relates to a device and method for early warning of coal spontaneous combustion through graded CO concentration. The device is particularly suitable for on-site monitoring of CO concentration in low-temperature coal oxidation gas in goafs. Background Art

[0002] Spontaneous combustion of coal is the leading cause of mine fires and a persistent threat to coal mine safety. Spontaneous combustion is a highly complex dynamic process, its formation and development occurring through a spontaneous, slow, and dynamically changing process of heat release, heat accumulation, and temperature rise leading to combustion. Determining the stage of spontaneous combustion and implementing graded early warning systems are key to preventing and controlling it. Early prediction of spontaneous combustion is a crucial component of the entire early warning and prevention process, particularly for fires caused by oxidation and heat generation from residual coal within underground mine goafs. This type of fire is a significant factor impacting mine safety.

[0003] Various methods for early prediction of coal spontaneous combustion have been developed both domestically and internationally, including indicator gas analysis, tracer release, and simulation. Among these, indicator gas analysis has received widespread attention for its practicality and reliability, and scholars at home and abroad have conducted extensive research on this topic. Compared to other indicator gases, CO has high concentrations and is easily detected. Therefore, CO is the most important indicator gas for coal spontaneous combustion fires and is of great value in predicting and forecasting coal spontaneous combustion in mines, as well as guiding the development of scientific and efficient firefighting plans.

[0004] However, CO gas produced during the early oxidation of coal in goafs is often difficult to accurately detect due to its low concentration, and its concentration in underground return air is very small. Consequently, some devices that could effectively monitor CO gas underground may fail to detect or measure inaccurately due to limited sensitivity of the analytical instruments, significantly hindering the effective use of CO to predict coal thermal state. Currently, the most widely used device for measuring CO concentration in spontaneous combustion coal gas is the gas chromatograph. A carrier gas carries the coal spontaneous combustion gas sample into a chromatographic column for separation. The separated gas components sequentially exit the column and enter the detector, which converts their concentration signals into electrical signals. After processing, a chromatographic elution curve is generated. The chromatographic peak corresponding to CO on this curve can be used to analyze CO concentration. However, this device is affected by CO concentration and is highly susceptible to factors such as ambient pressure, temperature, and humidity. This results in low accuracy, making it difficult to accurately monitor CO concentrations generated during small coal flow rates. Traditional adsorbent enrichment of CO gas produced during the early oxidation of coal in goafs is characterized by high-temperature desorption and has high temperature requirements, making it unsuitable for the complex underground environment. Therefore, developing a new device suitable for monitoring CO gas produced during the early oxidation process of residual coal in goaf is an urgent problem to be solved in the field of coal mine safety. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a coal spontaneous combustion early warning device and method through CO graded concentration.

[0006] In order to achieve the purpose of the present invention, the following technical scheme is specifically adopted: a coal spontaneous combustion early warning device through CO graded concentration, comprising a primary compression chamber, a secondary compression chamber, a gas detection chamber, an intelligent central control system, an air inlet pipeline, a first air outlet pipeline, a second air outlet pipeline, and a third air outlet pipeline. The air inlet of the primary compression chamber is connected to the air inlet pipeline, the air outlet of the primary compression chamber is connected to the air inlet of the secondary compression chamber via the first air outlet pipeline, the air outlet of the secondary compression chamber is connected to the air inlet of the gas detection chamber via the second air outlet pipeline, the air outlet of the gas detection chamber is connected to the third air outlet pipeline, and a pressure regulating device for regulating the pressure in the primary compression chamber is provided on the first air outlet pipeline. A first vacuum pump and a first intelligent stop valve are provided on the second outlet pipe in sequence, and a second intelligent stop valve, a second vacuum pump and a third intelligent stop valve for adjusting the pressure in the secondary compression chamber are provided. A first pressure sensor and a first temperature sensor are provided in the primary compression chamber, a second pressure sensor and a second temperature sensor are provided in the secondary compression chamber, and a TDLAS long optical path absorption cell is provided in the gas detection chamber. The first vacuum pump, the first intelligent stop valve, the second intelligent stop valve, the second vacuum pump, the third intelligent stop valve, the first pressure sensor, the first temperature sensor, the second pressure sensor, the second temperature sensor and the TDLAS long optical path absorption cell are all connected to the intelligent central control system.

[0007] Furthermore, a first adsorbent storage device is provided in the primary compression chamber, and activated alumina and silica gel are contained in the first adsorbent storage device.

[0008] Furthermore, the first adsorbent storage device is a metal screen, and the added weight ratio of activated alumina and silica gel is 1:1.

[0009] Furthermore, a second adsorbent storage device is provided in the secondary compression cabin, and a cuprous ion molecular sieve is installed in the second adsorbent storage device.

[0010] Furthermore, the second adsorbent storage device is a metal screen.

[0011] Furthermore, a third vacuum pump, a fourth intelligent stop valve, a filter and a fifth intelligent stop valve are sequentially provided on the air inlet pipeline along the air inlet direction for pressing the detected gas in the goaf into the primary compression chamber, and a sixth intelligent stop valve is provided on the third air outlet pipeline. The third vacuum pump, the fourth intelligent stop valve, the filter, the fifth intelligent stop valve and the sixth intelligent stop valve are all connected to the intelligent central control system.

[0012] Furthermore, the primary compression chamber, secondary compression chamber and gas detection chamber are all made of polymer composite materials.

[0013] The present invention also provides a coal spontaneous combustion early warning method through CO graded concentration, comprising the following steps:

[0014] a. The intelligent central control system controls the fourth and fifth intelligent stop valves and the third vacuum pump to open, while the first, second, third, and sixth intelligent stop valves are all closed. The gas to be tested in the goaf is pumped into the experimental device via the third vacuum pump. After passing through a filter to remove moisture and sulfide from the gas, it enters the primary compression chamber.

[0015] b. When the pressure of the primary compression chamber reaches the set negative pressure value, the fourth and fifth smart stop valves are closed;

[0016] c. After the fourth and fifth intelligent stop valves are closed for 5 minutes, the first vacuum pump and the first intelligent stop valve are opened to compress the detected gas in the goaf from the primary compression chamber into the secondary compression chamber. The pressure in the primary compression chamber decreases, while the pressure in the secondary compression chamber increases. When the pressure in the secondary compression chamber reaches the set negative pressure value, the first vacuum pump and the first intelligent stop valve are closed;

[0017] d. After the first intelligent stop valve is closed for 10 minutes, the second, third, and sixth intelligent stop valves and the second vacuum pump are opened to compress the gas to be detected in the goaf into the gas detection chamber and discharge it to the outside through the third outlet pipe. When the pressure in the secondary compression chamber and the gas detection chamber is the same, the sixth intelligent stop valve is closed to desorb the cuprous ion molecular sieve in the secondary compression chamber 11, enriching the CO gas and enabling the adsorbent to be reused.

[0018] e. When the secondary compression chamber is in a vacuum, the second and third intelligent stop valves are closed, and the gas detected in the goaf after desorption in step d enters the gas detection chamber. The TDLAS long optical path absorption cell located in the gas detection chamber is opened to collect and process the CO concentration signal in the desorbed gas detected in the goaf. The data is transmitted to the intelligent central control system via optical fiber for processing, analysis, and storage, and a graded warning is issued for the CO concentration in the gas detected in the goaf.

[0019] f. After the readings in the intelligent central control system stabilize, open all intelligent shutoff valves. When the pressures in the primary and secondary compression chambers are the same, close the first, second, third, and sixth intelligent shutoff valves.

[0020] g. Repeat steps a to f, and cycle through the operations in sequence.

[0021] Furthermore, the negative pressure value of the primary compression chamber in step b is set to 3.40 MPa, and the negative pressure value of the secondary compression chamber in step c is set to 3.20 MPa.

[0022] Furthermore, the step e is to provide a graded warning for the concentration of CO in the gas detected in the goaf as follows:

[0023] The first case: When the coal spontaneous combustion warning device that has been concentrated by CO graded is placed at the rear of the upper corner bracket of the fully mechanized caving face, if the CO concentration in the collected gas detected in the goaf is less than 50ppm, it is determined that there is no risk of spontaneous combustion of the remaining coal in the goaf, which is a first-level warning; if the CO concentration in the collected gas detected in the goaf is 50-500ppm, it is determined that the goaf is in the low-temperature oxidation stage and has the risk of spontaneous combustion, which is a second-level warning; if the CO concentration in the collected gas detected in the goaf is greater than 500ppm and less than 1000ppm, it is determined that the goaf is in the combustion stage, which is a third-level warning; if the CO concentration in the collected gas detected in the goaf is 1000-3000ppm, it is determined that the goaf is in the combustion stage and is accompanied by open flames, which is a fourth-level warning;

[0024] The second situation: When the coal spontaneous combustion warning device that has been concentrated through CO graded concentration is placed at the return air flow of the fully-mechanized caving face, if the CO concentration in the detected gas in the goaf is collected and is less than 24ppm, it is determined that there is no risk of coal spontaneous combustion, which is a first-level warning; if the CO concentration in the detected gas in the goaf is collected and is between 24 and 100ppm, it is determined that the fully-mechanized caving face has the risk of coal spontaneous combustion, which is a second-level warning; if the CO concentration in the detected gas in the goaf is collected and is greater than 100ppm, it is determined that coal spontaneous combustion has occurred in the fully-mechanized caving face, which is a third-level warning.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention adopts a two-step pressure swing adsorption method using a primary compression chamber and a secondary compression chamber. Utilizing the principle that adsorbents have different adsorption capacities for different gases at different pressures, the present invention first adsorbs CO2 in the gas being detected in the goaf through the primary compression chamber, thereby removing CO2 and increasing the concentration of CO gas. The gas being detected in the goaf is then adsorbed for the second time in the secondary compression chamber. Before desorption, the remaining gas being detected in the goaf after CO adsorption is discharged from the third gas outlet pipe through the gas detection chamber, thereby increasing the concentration of CO gas. The cuprous ion molecular sieve adsorbent in the secondary compression chamber is then desorbed, thereby enriching the CO gas generated by the low-temperature oxidation of coal in the goaf. This improves the detection accuracy of low-concentration CO gas and enables efficient monitoring of low-concentration CO gas.

[0027] 2. By utilizing the pressure swing adsorption method, the problem that traditional adsorbents (such as activated carbon, activated carbon fiber or molecular sieves) require high temperature (generally 150℃~350℃) for desorption is solved, making this device less affected by the surrounding environment and suitable for the complex environment of underground goaf areas.

[0028] 3. Through the hierarchical early warning method, effective measures and methods are provided for the prediction of spontaneous combustion of coal in underground goaf areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 Schematic diagram of the structure of the coal spontaneous combustion early warning device through CO graded concentration according to the present invention;

[0031] Figure 2 This is a control flow chart of the coal spontaneous combustion early warning method through CO graded concentration of the present invention.

[0032] In the figure: 1. Third vacuum pump, 2. Fourth intelligent stop valve, 3. Filter, 4. Fifth intelligent stop valve, 5. Primary compression chamber, 6. First adsorbent storage device, 7. First pressure sensor, 8. First temperature sensor, 9. First vacuum pump, 10. First intelligent stop valve, 11. Secondary compression chamber, 12. Second adsorbent storage device, 13. Second pressure sensor, 14. Second temperature sensor, 15. Second intelligent stop valve, 16. Second vacuum pump, 17. Third intelligent stop valve, 18. Gas detection chamber, 19. TDLAS long optical path absorption cell, 20. Sixth intelligent stop valve, 21. Intelligent central control system;

[0033] 100. Air inlet pipe, 200. First air outlet pipe, 300. Second air outlet pipe, 400. Third air outlet pipe. DETAILED DESCRIPTION

[0034] The following is a more detailed description of the present invention with reference to the accompanying drawings and specific embodiments, and further elaboration of the present invention.

[0035] Example 1

[0036] Reference Figure 1 A coal spontaneous combustion early warning device through CO graded concentration includes a primary compression chamber 5, a secondary compression chamber 11, a gas detection chamber 18, an intelligent central control system 21, an air inlet pipeline 100, a first air outlet pipeline 200, a second air outlet pipeline 300, and a third air outlet pipeline 400. The air inlet of the primary compression chamber 5 is connected to the air inlet pipeline 100, the air outlet of the primary compression chamber 5 is connected to the air inlet of the secondary compression chamber 11 through the first air outlet pipeline 200, the air outlet of the secondary compression chamber 11 is connected to the air inlet of the gas detection chamber 18 through the second air outlet pipeline 300, and the air outlet of the gas detection chamber 18 is connected to the third air outlet pipeline 400. A first vacuum pump 9 for adjusting the pressure in the primary compression chamber 5 and a first intelligent central control system 21 are provided on the first air outlet pipeline 200. A stop valve 10, a second intelligent stop valve 15, a second vacuum pump 16 for adjusting the pressure in the secondary compression chamber 11 and a third intelligent stop valve 17 are sequentially provided on the second gas outlet pipeline 300, a first pressure sensor 7 and a first temperature sensor 8 are provided in the primary compression chamber 5, a second pressure sensor 13 and a second temperature sensor 14 are provided in the secondary compression chamber 11, and a TDLAS long optical path absorption cell 19 is provided in the gas detection chamber 18. The first vacuum pump 9, the first intelligent stop valve 10, the second intelligent stop valve 15, the second vacuum pump 16, the third intelligent stop valve 17, the first pressure sensor 7, the first temperature sensor 8, the second pressure sensor 13, the second temperature sensor 14 and the TDLAS long optical path absorption cell 19 are all connected to the intelligent central control system 21.

[0037] A first adsorbent storage device 6 is provided in the primary compression chamber 5 , and activated alumina and silica gel are contained in the first adsorbent storage device 6 .

[0038] The first adsorbent storage device 6 is a metal screen, which is detachably installed in the middle position of the primary compression chamber 5. The added weight ratio of the activated alumina and the silica gel is 1:1.

[0039] A second adsorbent storage device 12 is provided in the secondary compression chamber 11. A cuprous ion molecular sieve is contained in the second adsorbent storage device 12. The second adsorbent storage device 12 is a metal mesh and is detachably mounted in the middle of the secondary compression chamber 11.

[0040] The mesh size of the metal screen of the first adsorbent storage device 6 and the second adsorbent storage device 12 is selected according to the mesh size and amount of the adsorbent, and is generally between 20 mesh and 40 mesh.

[0041] The first adsorbent storage device 6 and the second adsorbent storage device 12 are generally located in the middle of the primary compression chamber 5 and the secondary compression chamber 11, respectively. They are removable for adsorbent replacement, ensuring long-term use of the experimental device. In this embodiment, the first adsorbent storage device 6 contains a total weight of 500g of activated alumina and silica gel, with a ratio of 1:1. The second adsorbent storage device 12 contains a total weight of 600g of cuprous ion molecular sieve.

[0042] A third vacuum pump 1, a fourth intelligent stop valve 2, a filter 3 and a fifth intelligent stop valve 4 are sequentially provided on the air inlet pipeline 100 along the air inlet direction for pressing the detected gas in the goaf into the primary compression chamber 5, and a sixth intelligent stop valve 20 is provided on the third air outlet pipeline 400. The third vacuum pump 1, the fourth intelligent stop valve 2, the filter 3, the fifth intelligent stop valve 4 and the sixth intelligent stop valve 20 are all connected to the intelligent central control system 21.

[0043] The primary compression cabin 5, secondary compression cabin 11, and gas detection cabin 18 are all made of a polymer composite material with a thickness of 3 mm. Furthermore, the primary compression cabin 5, secondary compression cabin 11, and gas detection cabin 18 all include vertical cylindrical cabin bodies. The primary compression cabin 5 and secondary compression cabin 11 have the same structure, and the top and bottom surfaces of the cabin bodies are both arc-shaped. An air inlet and an air outlet are provided on the top and bottom surfaces of the cabin bodies of the primary compression cabin 5 and secondary compression cabin 11, respectively. The top and bottom surfaces of the gas detection cabin 18 are both circular flat plates, and an air outlet and an air inlet are provided on the top and bottom surfaces of the gas detection cabin 18, respectively. The inner diameter of the vertical cylindrical bodies of the primary compression cabin 5 and secondary compression cabin 11 is 40 mm, and the inner diameter of the vertical cylindrical body of the gas detection cabin 18 is 90 mm. The vertical height of the vertical cylindrical bodies of the primary compression cabin 5, secondary compression cabin 11, and gas detection cabin 18 is 300 mm. The cabin bodies of the primary compression cabin 5, the secondary compression cabin 11 and the gas detection cabin 18 can be opened and the parts therein can be replaced.

[0044] Filter 3 consists of a gas-water separator (model VO101) and a desulfurization device, and is used to remove moisture and sulfide from the gas being tested in the goaf.

[0045] In the present invention, the opening and closing of all intelligent stop valves, the opening and closing of the first vacuum pump 9, the second vacuum pump 16 and the third vacuum pump 1 are all controlled by the intelligent central control system 21. When the first pressure sensor 7, the first temperature sensor 8 in the primary compression chamber 5 and the second pressure sensor 13, the second temperature sensor 14 in the secondary compression chamber 11 transmit the pressure and temperature data in the primary compression chamber 5 and the secondary compression chamber 11 to the intelligent central control system 21 respectively. The intelligent central control system 21 collects and processes the information of the pressure and temperature data, and controls the opening and closing of the corresponding intelligent stop valves and vacuum pumps of the device by sending electromagnetic signals. The purpose of setting the first temperature sensor 8 and the second temperature sensor 14 is to prevent the device from overheating due to gas compression. If the primary compression chamber 5 and the secondary compression chamber 11 overheat (if the temperature is greater than 150°C), the intelligent central control system 21 controls the opening of all intelligent stop valves (the first intelligent stop valve 10, the second intelligent stop valve 15, the third intelligent stop valve 17, the fourth intelligent stop valve 2, the fifth intelligent stop valve 4, the sixth intelligent stop valve 20), and the third vacuum pump 1 presses air into the device for ventilation and cooling.

[0046] The gas flow in the coal spontaneous combustion early warning device through CO graded concentration of the present invention is as follows:

[0047] Air inlet pipeline 100 → filter 3 → primary compression chamber 5 → first air outlet pipeline 200 → secondary compression chamber 11 → second air outlet pipeline 300 → gas detection chamber 18 → third air outlet pipeline 400 → discharged to the outside.

[0048] Example 2

[0049] Reference Figure 1-Figure 2 A method for early warning of coal spontaneous combustion by CO graded concentration is implemented using the device for early warning of coal spontaneous combustion by CO graded concentration in Example 1, comprising the following steps:

[0050] a. The intelligent central control system 21 controls the fourth intelligent stop valve 2, the fifth intelligent stop valve 4, and the third vacuum pump 1 to open, while the first intelligent stop valve 10, the second intelligent stop valve 15, the third intelligent stop valve 17, and the sixth intelligent stop valve 20 are all closed. The gas to be tested in the goaf is pressed into the experimental device by the third vacuum pump 1. After the water and sulfide in the gas are removed by the filter 3, it enters the primary compression chamber 5.

[0051] b. When the pressure of the primary compression chamber 5 reaches the set negative pressure value (3.40 MPa), the fourth smart stop valve 2 and the fifth smart stop valve 4 are closed; the detected gas in the goaf is first adsorbed;

[0052] c. After the fourth and fifth intelligent stop valves 2 and 4 are closed for 5 minutes, the adsorption of the adsorbent reaches equilibrium, the CO2 is adsorbed, and the remaining gas is the gas after the CO2 is removed from the raw gas. The first vacuum pump 9 and the first intelligent stop valve 10 are opened to press the detected gas in the goaf from the primary compression chamber 5 into the secondary compression chamber 11. The pressure in the primary compression chamber 5 decreases, while the pressure in the secondary compression chamber 11 increases.

[0053] When the pressure of the secondary compression chamber 11 reaches the set negative pressure value (3.20 MPa), the first vacuum pump 9 and the first intelligent stop valve 10 are closed. The purpose of closing the first vacuum pump 9 and the first intelligent stop valve 10 is to allow the CO gas in the gas being detected in the goaf to be adsorbed by the cuprous ion molecular sieve in the secondary compression chamber 11 under high pressure, and to place the primary compression chamber 5 in a low pressure state, so that the adsorbent (activated alumina and silica gel) in the primary compression chamber 5 is desorbed and reduced.

[0054] d. After the first intelligent stop valve 10 is closed for 10 minutes, the second intelligent stop valve 15, the third intelligent stop valve 17, the sixth intelligent stop valve 20, and the second vacuum pump 16 are opened to press the remaining goaf gas after the adsorbent adsorbs the CO gas into the gas detection chamber 18 and discharge it to the outside through the third outlet pipe 400, further increasing the concentration of CO gas;

[0055] When the pressure in the secondary compression chamber 11 and the gas detection chamber 18 is the same, the sixth intelligent stop valve 20 is closed, so that the cuprous ion molecular sieve in the secondary compression chamber 11 is desorbed, CO gas is enriched, and the adsorbent is reused at the same time;

[0056] e. When the secondary compression chamber 11 is in a vacuum, the second intelligent stop valve 15 and the third intelligent stop valve 17 are closed. The gas detected in the goaf after desorption in step d enters the gas detection chamber. The TDLAS (tunable semiconductor laser absorption spectroscopy) long optical path absorption cell located in the gas detection chamber 18 is opened. The CO concentration signal in the desorbed gas detected in the goaf is collected and processed via the signal receiver. The data is transmitted to the intelligent central control system 21 via optical fiber for processing, analysis and storage, and a graded warning is issued for the CO concentration in the gas detected in the goaf.

[0057] f. After the readings in the intelligent central control system 21 stabilize, open all intelligent stop valves (the first intelligent stop valve 10, the second intelligent stop valve 15, the third intelligent stop valve 17, the fourth intelligent stop valve 2, the fifth intelligent stop valve 4, and the sixth intelligent stop valve 20). When the pressures in the primary and secondary compression chambers 5 and 11 are the same, close the first, second, third, and sixth intelligent stop valves 10, 15, 17, and 20.

[0058] g. Repeat steps a to f, and cycle through the operations in sequence.

[0059] The specific steps of performing graded warning on the concentration of CO in the gas detected in the goaf in step e are as follows:

[0060] The first case: Taking the goaf of a certain working face of a coal mine in Jining City as an example, the device is placed at the rear of the upper corner bracket of the fully mechanized caving face. If the CO concentration in the detected gas collected in the goaf is less than 50ppm, it is determined that there is a risk of spontaneous combustion of the remaining coal in the goaf, which is a first-level warning. At this time, the goaf is normal and no measures are needed; if the CO concentration in the detected gas collected in the goaf is 50-500ppm, it is determined that the goaf is in the low-temperature oxidation stage and has the risk of spontaneous combustion, which is a second-level warning. At this time, the cause needs to be identified and glue injection should be implemented to prevent fire. If the CO concentration in the gas detected in the goaf is greater than 500ppm and less than 1000ppm, it is determined that the goaf is in the combustion stage, which is a third-level warning. Production must be stopped immediately and glue injection should be implemented to extinguish the fire. If the CO concentration in the gas detected in the goaf is between 1000 and 3000ppm, it is determined that the goaf is in the combustion stage and is accompanied by open flames. This is a fourth-level warning. Production must be stopped immediately, the emergency plan must be activated, and glue injection should be implemented to extinguish the fire.

[0061] The second situation: Taking the goaf of a certain working face of a coal mine in Jining City as an example, the device is placed at the return air flow of the fully-mechanized caving face. If the CO concentration in the detected gas collected in the goaf is less than 24ppm, it is determined that there is no risk of coal spontaneous combustion, which is a first-level warning. At this time, the goaf is in normal condition and no measures need to be taken; if the CO concentration in the detected gas collected in the goaf is 24-100ppm, it is determined that the fully-mechanized caving face has the risk of coal spontaneous combustion, which is a second-level warning. It is necessary to immediately find out the cause and take preventive injection measures; if the CO concentration in the detected gas in the goaf is greater than 100ppm, it is determined that coal spontaneous combustion has occurred in the fully-mechanized caving face, which is a third-level warning. Production needs to be stopped immediately and nitrogen foam is injected to extinguish the fire.

[0062] The foregoing description is merely a preferred embodiment of the present invention, and these embodiments are by no means intended to limit the present invention in any way. It will be apparent to those skilled in the art that various modifications and variations may be made to the present invention. Any changes made by those skilled in the art, based on the teachings of this specification, to the embodiments of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A coal spontaneous combustion early warning device through CO graded concentration, characterized in that: The system comprises a primary compression chamber, a secondary compression chamber, a gas detection chamber, an intelligent central control system, an air inlet pipeline, a first air outlet pipeline, a second air outlet pipeline, and a third air outlet pipeline. The air inlet of the primary compression chamber is connected to the air inlet pipeline, the air outlet of the primary compression chamber is connected to the air inlet of the secondary compression chamber via the first air outlet pipeline, the air outlet of the secondary compression chamber is connected to the air inlet of the gas detection chamber via the second air outlet pipeline, the air outlet of the gas detection chamber is connected to the third air outlet pipeline, a first vacuum pump and a first intelligent stop valve for adjusting the pressure in the primary compression chamber are provided on the first air outlet pipeline, and a first intelligent stop valve and a first stop valve are provided on the second air outlet pipeline. A second intelligent stop valve, a second vacuum pump for adjusting the pressure in the secondary compression chamber, and a third intelligent stop valve are sequentially provided on it; a first pressure sensor and a first temperature sensor are provided in the primary compression chamber, a second pressure sensor and a second temperature sensor are provided in the secondary compression chamber, and a TDLAS long optical path absorption cell is provided in the gas detection chamber; the first vacuum pump, the first intelligent stop valve, the second intelligent stop valve, the second vacuum pump, the third intelligent stop valve, the first pressure sensor, the first temperature sensor, the second pressure sensor, the second temperature sensor, and the TDLAS long optical path absorption cell are all connected to the intelligent central control system; A first adsorbent storage device is provided in the primary compression chamber, and activated alumina and silica gel are contained in the first adsorbent storage device; A second adsorbent storage device is provided in the secondary compression cabin, and cuprous ion molecular sieve is installed in the second adsorbent storage device.

2. The coal spontaneous combustion early warning device through CO graded concentration according to claim 1, characterized in that: The first adsorbent storage device is a metal screen, and the added weight ratio of activated alumina and silica gel is 1:

1.

3. The coal spontaneous combustion early warning device through CO graded concentration according to claim 1, characterized in that: The second adsorbent storage device is a metal screen.

4. The coal spontaneous combustion early warning device through CO graded concentration according to claim 1, characterized in that: A third vacuum pump, a fourth intelligent stop valve, a filter and a fifth intelligent stop valve are sequentially arranged on the air inlet pipeline along the air inlet direction for pressing the detected gas in the goaf into the primary compression chamber, and a sixth intelligent stop valve is arranged on the third air outlet pipeline. The third vacuum pump, the fourth intelligent stop valve, the filter, the fifth intelligent stop valve and the sixth intelligent stop valve are all connected to the intelligent central control system.

5. The coal spontaneous combustion early warning device through CO graded concentration according to claim 1, characterized in that: The primary compression cabin, the secondary compression cabin and the gas detection cabin are all made of high polymer composite materials.

6. A method for early warning of coal spontaneous combustion by CO graded concentration, implemented by the device for early warning of coal spontaneous combustion by CO graded concentration as claimed in claim 4, characterized in that: The steps include: a. The intelligent central control system controls the fourth and fifth intelligent stop valves and the third vacuum pump to open, while the first, second, third, and sixth intelligent stop valves are all closed. The gas to be tested in the goaf is pumped into the experimental device via the third vacuum pump. After passing through a filter to remove moisture and sulfide from the gas, it enters the primary compression chamber. b. When the pressure of the primary compression chamber reaches the set negative pressure value, the fourth and fifth smart stop valves are closed; c. After the fourth and fifth intelligent stop valves are closed for 5 minutes, the first vacuum pump and the first intelligent stop valve are opened to compress the detected gas in the goaf from the primary compression chamber into the secondary compression chamber. The pressure in the primary compression chamber decreases, while the pressure in the secondary compression chamber increases. When the pressure in the secondary compression chamber reaches the set negative pressure value, the first vacuum pump and the first intelligent stop valve are closed; d. After the first intelligent stop valve is closed for 10 minutes, the second, third, and sixth intelligent stop valves and the second vacuum pump are opened to compress the gas to be detected in the goaf into the gas detection chamber and discharge it to the outside through the third outlet pipe. When the pressure in the secondary compression chamber and the gas detection chamber is the same, the sixth intelligent stop valve is closed to desorb the cuprous ion molecular sieve in the secondary compression chamber, enriching the CO gas and enabling the adsorbent to be reused. e. When the secondary compression chamber is in a vacuum, the second and third intelligent stop valves are closed, and the gas detected in the goaf after desorption in step d enters the gas detection chamber. The TDLAS long optical path absorption cell located in the gas detection chamber is opened to collect and process the CO concentration signal in the desorbed gas detected in the goaf. The data is transmitted to the intelligent central control system via optical fiber for processing, analysis, and storage, and a graded warning is issued for the CO concentration in the gas detected in the goaf. f. After the readings in the intelligent central control system stabilize, open all intelligent shutoff valves. When the pressures in the primary and secondary compression chambers are the same, close the first, second, third, and sixth intelligent shutoff valves. g. Repeat steps a to f, and cycle through the operations in sequence.

7. The method for early warning of coal spontaneous combustion by CO graded concentration according to claim 6, characterized in that: The negative pressure value of the primary compression chamber in step b is set to 3.40 MPa, and the negative pressure value of the secondary compression chamber in step c is set to 3.20 MPa.

8. The method for early warning of coal spontaneous combustion by CO staged concentration according to claim 6, characterized in that: The specific steps of performing graded warning on the concentration of CO in the gas detected in the goaf in step e are as follows: The first case: When the coal spontaneous combustion warning device that has been concentrated by CO graded is placed at the rear of the upper corner bracket of the fully mechanized caving face, if the CO concentration in the collected gas detected in the goaf is less than 50ppm, it is determined that there is no risk of spontaneous combustion of the remaining coal in the goaf, which is a first-level warning; if the CO concentration in the collected gas detected in the goaf is 50-500ppm, it is determined that the goaf is in the low-temperature oxidation stage and has natural hidden dangers, which is a second-level warning; if the CO concentration in the collected gas detected in the goaf is greater than 500ppm and less than 1000ppm, it is determined that the goaf is in the combustion stage, which is a third-level warning; if the CO concentration in the collected gas detected in the goaf is 1000-3000ppm, it is determined that the goaf is in the combustion stage and is accompanied by open flames, which is a fourth-level warning; The second situation: When the coal spontaneous combustion warning device that has been concentrated through CO graded concentration is placed at the return air flow of the fully-mechanized caving face, if the CO concentration in the detected gas in the goaf is collected and is less than 24ppm, it is determined that there is no risk of coal spontaneous combustion, which is a first-level warning; if the CO concentration in the detected gas in the goaf is collected and is between 24 and 100ppm, it is determined that the fully-mechanized caving face has the risk of coal spontaneous combustion, which is a second-level warning; if the CO concentration in the detected gas in the goaf is collected and is greater than 100ppm, it is determined that coal spontaneous combustion has occurred in the fully-mechanized caving face, which is a third-level warning.

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