Coal seam and goaf combined CO2 micro-nano bubble water injection fire suppression system and application thereof

Abstract

The invention discloses a coal seam and goaf combined CO2 micro-nano bubble water injection fire suppression system and application thereof. The system comprises a CO2 micro-nano bubble water injection unit and a gas extraction unit which are arranged around a working face; cO2 micro-nano bubble water is generated through a pipeline and is conveyed to a coal seam and a goaf at the same time, and coal seam gas is displaced. According to the method, the micro-CO2 micro-nano bubble water is injected into the coal seam and the goaf at the same time, CO2 displaces a large amount of gas existing in coal seam cracks, and the concentration of combustible matter in the coal seam is reduced; cO2 micro-nano bubble water is injected into the goaf, CO2 gas is dissolved in water in the form of micro-nano bubbles, the concentration is very high, a large amount of CO2 gas is decomposed after the CO2 gas is heated, a gas barrier is formed in a high-temperature area, oxygen is blocked, combustibles are reduced, fire disasters are inhibited, and the probability of occurrence of the fire disasters in the goaf is reduced.

Description

Technical Field

[0001] The present invention relates to the field of coal seam and goaf fire control, in particular to gas displacement extraction and goaf injection of CO2 micro-nano bubble water to suppress fire, specifically to a coal seam and goaf joint CO2 micro-nano bubble water fire suppression system and its application. Background Art

[0002] Coal mine gas, also known as coalbed methane, gushes out from coal seams or rock formations and is one of the five major disasters that affect coal mine safety production. At the same time, the main component of gas is methane, which is a clean energy source. Coal seam gas extraction is an effective way to achieve gas control and energy utilization. Coal seam water injection technology promotes the development of coal body fissures and effectively displaces gas by injecting water into the coal seam at high pressure. It is an effective method to improve the efficiency of gas extraction, and it can also play a role in wetting and dust reduction of the coal body. For fires in coal mine areas, it is necessary not only to consider how to reduce the concentration of combustibles in the coal seam and goaf, but also to consider how to reduce the temperature of the goaf so that the temperature cannot reach the ignition point. At present, domestic and foreign scholars have confirmed through research that CO2 gas has stronger adsorption performance than gas in coal pore fissures. Water has a displacing effect on gas, but pure water has poor mass transfer efficiency in coal seams, and micro-nano bubble water has higher mass transfer efficiency; injecting CO2 gas into the coal seam will leave less in the coal seam and it is not easy to inject into the coal seam. In order to solve this problem, CO2 micro-nano bubble water with good mass transfer efficiency is used instead of pure water for coal seam injection. In reality, CO2 micro-nano bubble water is injected into the coal seam to displace gas and reduce the concentration of combustibles, and to moisten the coal seam to achieve the purpose of dust reduction. The goaf is adjacent to the coal seam, and a fire in the goaf will also affect the coal seam. Therefore, the joint suppression of fire in the goaf and coal seam is the fundamental way to achieve fire control. Summary of the invention

[0003] While overcoming the technical background problems, the present invention application firstly provides a system for suppressing fire by injecting CO2 micro-nano bubble water into coal seams and goafs, and secondly provides an application of the system for suppressing fires.

[0004] To achieve the above-mentioned invention object, the technical solution adopted by the present invention is: a coal seam and goaf joint injection CO2 micro-nano bubble water fire suppression system, including a CO2 micro-nano bubble water injection unit and a gas extraction unit arranged around the working face; The CO2 micro-nano bubble water injection unit comprises an air pump (3), a CO2 gas tank (4), a micro-nano bubble generator (5), a CO2 micro-nano bubble water delivery main pipeline (12), a CO2 micro-nano bubble water delivery branch pipeline (6), and a CO2 micro-nano bubble water injection valve (17); the micro-nano bubble generator (5) is connected to the air pump (3) and the CO2 gas tank (4); the outlet of the micro-nano bubble generator (5) is connected to the CO2 micro-nano bubble water delivery main pipeline (12); a plurality of CO2 micro-nano bubble water delivery branch pipelines (6) are arranged on the CO2 micro-nano bubble water delivery main pipeline (12), and the CO2 micro-nano bubble water delivery branch pipelines (6) are respectively connected to the water injection boreholes in the goaf and the coal seam through the water injection borehole sealing device (7); The gas extraction unit comprises a gas extraction main line (10), a gas extraction branch line (15) and a gas extraction device (13); the gas extraction device (13) is arranged on the gas extraction main line (10), and a plurality of gas extraction branch lines (15) are connected to the gas extraction main line (10); each gas extraction branch line (15) is connected to a gas extraction borehole distributed inside a CO2 micro-nano bubble water injection borehole in a mined coal seam through a gas extraction borehole sealing device (18).

[0005] As a preferred technical solution: the micro-nano bubble generator (5) adopts a high-pressure dissolved air micro-nano bubble generator to efficiently convert CO2 gas into micro-nano bubble water, and the bubble diameter is 10-1000 nanometers.

[0006] As a preferred technical solution: a CO2 micro-nano bubble water injection valve (17) is installed on the CO2 micro-nano bubble water transmission branch pipeline (6); a gas collection valve (11) is installed on the gas extraction branch pipeline (15); and a gas safety monitoring device (8) and a flow meter (9) are installed on the gas extraction main pipeline (10).

[0007] As a preferred technical solution: the micro-nano bubble generator (5) is connected to a water source delivery pipeline, an air pump (3), and an air tank (4), and the water source is a water source for use on the working surface.

[0008] The invention discloses an application of a coal seam and goaf joint injection CO2 micro-nano bubble water fire suppression system, wherein CO2 micro-nano bubble water is injected into the goaf and the coal seam simultaneously.

[0009] As a preferred technical solution: the application method includes the following specific steps: S1: System Check and Preparation Check the components of the CO2 micro-nano bubble water injection unit and the gas extraction unit to ensure that the equipment is operating normally, the instrument display is accurate, and the valves are in the correct state; S2: Injection of CO2 micro-nano bubble water The water source is the water source for the working face, and the water source is connected to the micro-nano bubble generator.

[0010] The valves on the CO2 micro-nano bubble water delivery main pipeline (12) and the corresponding CO2 micro-nano bubble water injection branch pipe valves (6) are opened in sequence, and the CO2 micro-nano bubble water is injected into the water injection boreholes of the coal seam and the goaf respectively through the water injection borehole sealing device (7), and the suffocation and cooling properties of CO2 are used to suppress the fire hazards that may occur in the goaf. During the gas injection process, the flow rate and pressure are also controlled through the corresponding valves, and the gas composition and temperature of the goaf are monitored; S3: Gas Displacement While injecting CO2 micro-nano bubble water into the coal seam, the gas extraction pump (13) is turned on, and the gas collection valve (11) of the gas extraction branch (15) is opened. The gas enters the gas extraction branch (15) through the gas extraction drilling hole sealing device (18), is collected in the gas extraction main road (10), and is finally transported to the gas storage device (14).

[0011] As a preferred technical solution: in step S2, according to the geological parameters of the coal seam such as porosity, permeability and previous gas content measurement results, the injection speed and injection amount of micro-nano bubble water are monitored in real time to achieve the displacement of coal seam gas, reduce the concentration of combustibles, and achieve fire suppression.

[0012] As a preferred technical solution: in step S3, the gas safety monitoring device (8) monitors the gas concentration in the gas extraction main line (10) in real time, and when the gas concentration exceeds a set safety threshold, an alarm is issued and corresponding safety measures are taken.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention simultaneously injects micro-CO2 micro-nano bubble water into the coal seam and goaf, and the mass transfer efficiency of micro-nano bubbles is high; 2. CO2 displaces a large amount of gas existing in the cracks of the coal seam, reducing the concentration of combustibles in the coal seam; 3. Compared with pure water, micro-nano bubble water is easier to inject into coal seams and store in coal seams and goafs. CO2 is a flame retardant gas, which plays a role in flame retardancy and fire suppression; 4. CO2 micro-nano bubble water is injected into the goaf. The CO2 gas is dissolved in the water in the form of micro-nano bubbles at a high concentration. After being heated, a large amount of CO2 gas will decompose, thus forming a gas barrier in the high-temperature area, blocking oxygen, reducing combustibles, suppressing fires, and reducing the probability of fires in goafs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the overall layout of the present invention.

[0015] Figure 2 It is a process flow chart of the present invention application.

[0016] Among them: air pump 3; CO2 gas tank 4; pressure gauge 16; micro-nano bubble generating device 5; CO2 micro-nano bubble water injection main pipe 12; CO2 micro-nano bubble water injection branch pipe 6; CO2 micro-nano bubble injection valve 17; water injection drilling sealing device 7; gas extraction branch pipe 15; gas extraction branch pipe valve 11; coal seam 2; gas safety monitoring device 8; flow meter 9; goaf 2; gas extraction device 13; gas storage device 14; gas extraction drilling sealing device 18; gas extraction main pipe 10; working face 19. DETAILED DESCRIPTION

[0017] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0018] See attached Figure 1 The fire suppression system disclosed in the present invention mainly adopts the method of injecting CO2 micro-nano bubble water into the mined coal seam to displace gas and injecting CO2 micro-nano bubble water into the goaf to reduce the O2 density. The two areas are jointly managed to achieve the purpose of suppressing fire.

[0019] The coal seam and goaf joint injection CO2 micro-nano bubble water fire suppression system includes a CO2 micro-nano bubble water injection unit and a gas extraction unit arranged around the working face to achieve the generation and transportation of CO2 micro-nano bubble water, and the extraction and transportation of coal seam gas.

[0020] As a preferred embodiment, the CO2 micro-nano bubble water injection unit includes an air pump 3, a CO2 gas tank 4, a micro-nano bubble generator 5, a CO2 micro-nano bubble water delivery main pipeline 12, a CO2 micro-nano bubble water delivery branch pipeline 6, and a CO2 micro-nano bubble water injection valve 17. The micro-nano bubble generator 5 is connected to the air pump 3 and the CO2 gas tank 4; the outlet of the micro-nano bubble generator 5 is connected to the CO2 micro-nano bubble water delivery main pipeline 12; the CO2 micro-nano bubble water delivery main pipeline 12 is provided with a plurality of CO2 micro-nano bubble water delivery branch pipelines 6, and the CO2 micro-nano bubble water delivery branch pipelines 6 are respectively connected to the water injection boreholes in the goaf and the coal seam through the water injection drilling sealing device 7. Figure 1 In this embodiment, a CO2 micro-nano bubble water delivery main pipeline 12 and six CO2 micro-nano bubble water delivery branch pipelines 6 are provided.

[0021] As a preferred solution, the micro-nano bubble generator 5 uses a high-pressure dissolved air micro-nano bubble generator to efficiently convert CO2 gas into micro-nano bubble water, and the bubble diameter is 10-1000 nanometers, ensuring good mass transfer and displacement effect in the pores of the coal seam. A CO2 micro-nano bubble water injection valve 17 is installed on the CO2 micro-nano bubble water delivery branch pipeline 6. The micro-nano bubble generator 5 is connected to the air pump 3 and the CO2 gas tank 4 through a pipeline, and a pressure gauge 16 is installed on the pipeline connecting the CO2 gas tank 4 and the micro-nano bubble generator 5.

[0022] As a preferred embodiment, the gas extraction unit includes a gas extraction main line 10, a gas extraction branch line 15 and a gas extraction device 13. The gas extraction device 13 is arranged on the gas extraction main line 10, and a plurality of gas extraction branch lines 15 are connected to the gas extraction main line 10; each gas extraction branch line 15 is connected to the gas extraction borehole distributed inside the CO2 micro-nano bubble water injection borehole in the mined coal seam through a gas extraction borehole sealing device 18.

[0023] As a preferred solution, the gas extraction main line 10 is connected to the gas storage device 14, and the gas safety monitoring device 8, flow meter 9 and gas extraction pump 13 are installed on the gas extraction main line 10; the gas collection valve 11 is installed on the gas extraction branch line 15. By utilizing the excellent mass transfer property of micro-nano bubble water and the high solubility of CO2 in micro-nano bubble water, gas is displaced so that CO2 can be stored in the goaf and is not easy to leak. In addition, the content of combustibles in the goaf is reduced, the combustibility of the coal seam is reduced, and the occurrence of fire is prevented, achieving the purpose of "one work, multiple effects".

[0024] As a preferred solution, the gas extraction boreholes are distributed inside the water injection boreholes, and the distance between the water injection boreholes and the gas extraction boreholes is 5-10 meters.

[0025] The water injection drilling sealing device 7 adopts a structure combining sealing materials and sealing components, which can not only ensure good sealing and prevent leakage of CO2 micro-nano bubble water, but also adapt to stratum deformation during coal seam mining.

[0026] The above system is used to implement the joint injection of CO2 micro-nano bubble water into the coal seam and goaf to suppress fire. The most important application operation is to inject CO2 micro-nano bubble water into the goaf and coal seam at the same time.

[0027] The system application process includes the following specific steps: S1: System Check and Preparation Check the components of the CO2 micro-nano bubble water injection pipeline and the gas extraction pipeline to ensure that the air pump 3, gas extraction pump 13 and other equipment are operating normally, the pressure gauge 16, flow meter 9 and other instruments display accurately, and all valves are in the correct state. At the same time, check the sensitivity and reliability of the gas safety monitoring device 8 to ensure that it can monitor the changes in gas concentration in real time.

[0028] S2: Injected CO2 micro-nano bubble water A water source is introduced into the working face, and the air pump (3) is turned on to transport the CO2 gas in the CO2 gas tank (4) to the micro-nano bubble generator (5). The air pump pressure is adjusted to generate CO2 micro-nano bubble water in the micro-nano bubble generator (5). The valves on the CO2 micro-nano bubble water transport main pipeline (12) and the corresponding CO2 micro-nano bubble water injection branch pipe valves (6) are opened in sequence. The CO2 micro-nano bubble water is injected into the coal seam borehole and the goaf borehole through the water injection drilling sealing device (7), and the injection speed and injection amount of the micro-nano bubble water are monitored in real time.

[0029] S3: Gas Displacement While injecting CO2 micro-nano bubble water into the coal seam, the gas extraction pump 13 is turned on, and the gas collection valve 11 of the gas extraction branch 15 is opened, so that the gas enters the gas extraction branch 15 through the gas extraction drilling hole sealing device 18, and then is collected in the gas extraction main road 10, and finally transported to the gas storage device 14. The gas safety monitoring device 8 monitors the gas concentration in the gas extraction main road in real time. When the gas concentration exceeds the set safety threshold, an alarm is issued and corresponding safety measures are taken, such as adjusting the extraction pump speed or stopping the gas injection operation in some areas.

[0030] In step S2, according to the geological parameters of the coal seam, such as porosity, permeability and the results of the previous gas content measurement, the injection speed and injection amount of micro-nano bubble water are monitored in real time to ensure that the coal seam structure will not be damaged while displacing the gas and to achieve the optimal displacement efficiency, so as to achieve the displacement of coal seam gas, reduce the concentration of combustibles and achieve fire suppression.

[0031] In step S2, when CO2 micro-nano bubble water is injected into the goaf, the gas injection drilling holes and the gas injection sequence are reasonably arranged in combination with the spatial distribution and ventilation conditions of the goaf, so that the CO2 micro-nano bubble water can be evenly distributed in the goaf. After being heated, a large amount of CO2 gas is decomposed to form a gas barrier, blocking oxygen and achieving fire suppression.

[0032] In step S3, the gas extraction borehole is regularly inspected and maintained to clear any blockages that may occur in the borehole to ensure smooth gas extraction. At the same time, the gas extraction pump 13 is regularly maintained to adjust its operating parameters to meet the gas extraction requirements at different stages.

[0033] Fire prevention and extinguishing in coal mines must consider the isolation of goaf areas to suppress fire sources and the reduction of combustible concentrations in the coal seams. The two areas must be implemented in combination to suppress fires. The amount of CO2 gas dissolved in water in the form of micro-nano bubbles will increase significantly. CO2 micro-nano bubble water is heated in the heated goaf to produce a large amount of CO2 gas volatilization, forming a flame retardant isolation effect. At the same time, the coal seam is close to the goaf. The CO2 micro-nano bubble water is used to displace gas in the coal seam and remove flammable and explosive gases (methane) in the coal seam, which is of great significance for reducing the probability of fire from the perspective of reducing combustibles. The adsorption capacity of CO2 is more than 40 times that of methane, and CO2 remaining in the coal seam will also suppress fires.

[0034] The process flow of using the above system to displace gas and suppress fire is shown in the attached Figure 2 , according to the specific implementation method of the process flow: a. Arrange coal seam gas mining at a depth of less than 1,000 meters, evenly arrange water injection boreholes in the gas extraction coal seam 11, arrange gas extraction boreholes around the water injection boreholes, and the gas extraction boreholes are distributed inside the micro-nano bubble water injection boreholes. The distance between the micro-nano bubble water injection boreholes and the gas extraction boreholes is 5-10 meters.

[0035] b. After the CO2 micro-nano bubble water injection and gas extraction arrangement of goaf 1 are completed, pipelines are laid, which can be divided into micro-nano bubble water injection pipelines and gas extraction pipelines. Installation is as shown in the attached Figure 1 A gas displacement fire suppression system is shown.

[0036] c. By controlling the gas extraction of each gas extraction branch pipe 15, the gas is transported to the gas storage device 14 through the gas extraction main line 10 after being processed, thus completing the gas extraction work: After the micro-nano bubble water is injected, gas extraction is carried out through the gas extraction boreholes arranged around the water injection boreholes, and each gas extraction borehole is sealed by the gas extraction borehole sealing device 17. The gas collection valve 11 of each gas extraction branch 15 is opened, and the gas of each gas extraction branch 15 is extracted through the gas extraction pump 13. The gas collection valve 11 of each gas extraction branch 15 is commonly connected to the gas safety monitoring device 8 to realize the monitoring and control of the pressure, flow and other safety factors in the gas extraction process.

[0037] During the gas extraction process, the switch of the gas collection valve 11 of each gas extraction branch can be controlled to be closed, and each branch can extract gas at the same time. It is also possible to select some branches to extract gas intermittently according to actual conditions, so as to achieve reasonable and efficient gas extraction.

[0038] The present invention utilizes CO2 micro-nano bubble water to displace coal seam gas, and at the same time, injects CO2 micro-nano bubble water into the goaf to suppress fire. A micro-nano bubble generating device 5 is arranged at the wellhead of the working face 19, and micro-nano bubble water is injected into the main pipe 12 through CO2 micro-nano bubble water, and sent to the coal seam 2 to displace gas and accelerate the gas desorption speed; and sent to the goaf 1 to reduce the content of combustion-supporting materials and effectively suppress the occurrence of fire.

Claims

1. A fire suppression system for coal seam and goaf area joint injection of CO2 micro-nano bubble water, characterized by: It includes a CO2 micro-nano bubble water injection unit and a gas extraction unit arranged around the working face; The CO2 micro-nano bubble water injection unit comprises an air pump (3), a CO2 gas tank (4), a micro-nano bubble generator (5), a CO2 micro-nano bubble water delivery main pipeline (12), a CO2 micro-nano bubble water delivery branch pipeline (6), and a CO2 micro-nano bubble water injection valve (17); the micro-nano bubble generator (5) is connected to the air pump (3) and the CO2 gas tank (4); the outlet of the micro-nano bubble generator (5) is connected to the CO2 micro-nano bubble water delivery main pipeline (12); a plurality of CO2 micro-nano bubble water delivery branch pipelines (6) are arranged on the CO2 micro-nano bubble water delivery main pipeline (12), and the CO2 micro-nano bubble water delivery branch pipelines (6) are respectively connected to the water injection boreholes in the goaf and the coal seam through the water injection borehole sealing device (7); The gas extraction unit comprises a gas extraction main line (10), a gas extraction branch line (15) and a gas extraction device (13); the gas extraction device (13) is arranged on the gas extraction main line (10), and a plurality of gas extraction branch lines (15) are connected to the gas extraction main line (10); each gas extraction branch line (15) is connected to a gas extraction borehole distributed inside a CO2 micro-nano bubble water injection borehole in a mined coal seam through a gas extraction borehole sealing device (18).

2. The coal seam and goaf joint CO2 micro-nano bubble water fire suppression system according to claim 1 is characterized by: The micro-nano bubble generator (5) adopts a high-pressure dissolved air type micro-nano bubble generator to efficiently convert CO2 gas into micro-nano bubble water, and the bubble diameter is 10-1000 nanometers.

3. The fire suppression system for coal seam and goaf combined with CO2 micro-nano bubble water injection according to claim 1 is characterized in that: A CO2 micro-nano bubble water injection valve (17) is installed on the CO2 micro-nano bubble water transmission branch pipeline (6); a gas collection valve (11) is installed on the gas extraction branch pipeline (15); and a gas safety monitoring device (8) and a flow meter (9) are installed on the gas extraction main pipeline (10).

4. The coal seam and goaf joint CO2 micro-nano bubble water fire suppression system according to claim 1 is characterized by: The micro-nano bubble generator (5) is connected to a water source delivery pipeline, an air pump (3), and an air tank (4), and the water source is a water source for use on the working surface.

5. An application of a coal seam and goaf joint CO2 micro-nano bubble water fire suppression system as claimed in any one of claims 1 to 4, characterized in that: CO2 micro-nano bubble water is injected into the goaf and coal seam simultaneously.

6. The application of the coal seam and goaf joint CO2 micro-nano bubble water fire suppression system according to claim 5 is characterized in that: The specific steps include: S1: System Check and Preparation Check the components of the CO2 micro-nano bubble water injection unit and the gas extraction unit to ensure that the equipment is operating normally, the instrument display is accurate, and the valves are in the correct state; S2: Injection of CO2 micro-nano bubble water The water source is the water source for the working face, and the water source is connected to the micro-nano bubble generator; The valves on the CO2 micro-nano bubble water delivery main pipeline (12) and the corresponding CO2 micro-nano bubble water injection branch pipe valves (6) are opened in sequence, and the CO2 micro-nano bubble water is injected into the water injection boreholes of the coal seam and the goaf respectively through the water injection borehole sealing device (7), and the suffocation and cooling properties of CO2 are used to suppress the fire hazards that may occur in the goaf. During the gas injection process, the flow rate and pressure are also controlled through the corresponding valves, and the gas composition and temperature of the goaf are monitored; S3: Gas Displacement While injecting CO2 micro-nano bubble water into the coal seam, the gas extraction pump (13) is turned on, and the gas collection valve (11) of the gas extraction branch (15) is opened. The gas enters the gas extraction branch (15) through the gas extraction drilling hole sealing device (18), is collected in the gas extraction main road (10), and is finally transported to the gas storage device (14).

7. The application of the coal seam and goaf joint CO2 micro-nano bubble water fire suppression system according to claim 6 is characterized in that: In step S2, according to the geological parameters of the coal seam such as porosity, permeability and previous gas content measurement results, the injection speed and injection amount of micro-nano bubble water are monitored in real time to achieve the displacement of coal seam gas, reduce the concentration of combustibles, and achieve fire suppression.

8. The application of the coal seam and goaf joint CO2 micro-nano bubble water fire suppression system according to claim 6 is characterized in that: In step S3, the gas safety monitoring device (8) monitors the gas concentration in the gas extraction main pipeline (10) in real time. When the gas concentration exceeds a set safety threshold, an alarm is issued and corresponding safety measures are taken.

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