A closed-loop system for coal mine gas development and utilization and waste gas emission reduction and its use method

Abstract

The present invention discloses a closed-loop system for coal mine gas development and utilization and waste gas emission reduction and a method for using the system. The system includes a closed-loop gas development system, a gas power generation system and a waste gas reinjection system. The system utilizes high-temperature hot waste gas generated by coal fire and gas power generation to displace coal seam gas, which not only increases the output of coal seam gas, but also reduces the emission of greenhouse gases in coal mining areas. It plays an important role in building green mines and achieving national carbon neutrality. In addition, since the injection of high-temperature waste gas into coal seams will cause the coal body to expand and deform, the permeability is greatly reduced, and the injection amount of high-temperature waste gas is small, in order to overcome this problem, the present invention proposes to provide an external expansion space for the coal body through high-pressure water jet cavity creation, so as to prevent the permeability of the coal seam from being reduced due to expansion caused by high temperature and adsorption, which is conducive to increasing the injection amount of waste gas.

Description

Technical Field

[0001] The present invention relates to the technical field of efficient development of coal mining resources and carbon emission reduction, and in particular to a closed-loop system for coal mine gas development and utilization and waste gas emission reduction and a method for using the system. Background Art

[0002] Coal seam gas, as a byproduct of coal formation, is not only a strong greenhouse gas and a dangerous source of safety in dangerous coal mines, but also an efficient clean energy source. Therefore, achieving efficient development of coal mine gas is of great significance for ensuring safe production in coal mines, protecting the environment, and realizing energy resource utilization. However, due to the high adsorption characteristics of coal seams in my country, conventional gas extraction methods can only extract favorable gas in coal seams, while a large amount of adsorbed gas still remains in the coal seams, which poses a safety hazard to the later coal seam recovery.

[0003] In addition, a large amount of gas is discharged into the air during the coal production process, which greatly increases the carbon emissions in the coal mining area and causes serious environmental pollution, which does not meet the current national requirements for building green mines. For this reason, many mining areas have established gas power plants to use the extracted gas for power generation, reducing greenhouse gas emissions. However, a large amount of high-temperature exhaust gas is generated during gas power generation, containing a large amount of CO2 and other gases that are harmful to the environment. If these high-temperature exhaust gases are directly discharged into the atmosphere, it will cause serious environmental damage.

[0004] In view of the above problems, there is an urgent need to seek a system and method that can not only strengthen the development of coal mine gas, but also achieve greenhouse gas emission reduction in coal mining areas. Summary of the invention

[0005] In view of the above-mentioned technical deficiencies, the purpose of the present invention is to provide a closed-loop system for coal mine gas development and utilization and waste gas emission reduction and a method of use, which overcomes the current problems of high-temperature waste gas injection into coal seams causing coal body expansion and deformation, a significant reduction in permeability, and a small amount of high-temperature waste gas injection, thereby increasing the output of coalbed methane and reducing greenhouse gas emissions in coal mining areas. It plays an important role in building green mines and achieving national carbon neutrality.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention provides a closed-loop system for coal mine gas development and utilization and waste gas emission reduction, including a gas development system, a gas power generation system and a waste gas reinjection system;

[0008] The gas development system includes an extraction pump station, a slaked lime filtrate pool, a wire mesh filter device and a gas storage tank which are sequentially connected together through pipelines, and the extraction end of the extraction pump station is connected to the extraction well;

[0009] The gas power generation system comprises a flame arrester, a dehydration device, a gas turbine, a shaft generator and a tail gas temporary storage tank group which are sequentially connected together through pipelines; the flame arrester is connected to the outlet of the gas storage tank;

[0010] The exhaust gas reinjection system includes a water pump group connected to a water reservoir, a gas booster pump group connected to a tail gas temporary storage tank group, and a gas-liquid-solid separator. The tail gas temporary storage tank group and the gas booster pump group can withstand a high temperature of 500-800°C;

[0011] The inlet of the gas-liquid-solid separator is connected to the gas-water-coal lifting well, the outlet of the gas-liquid-solid separator is respectively connected to the entrance of the water reservoir, the coal bunker and the extraction pump station, and the outlets of the water pump group and the gas booster pump group are both connected to the inlet of the waste gas injection well;

[0012] A long hole is drilled at the bottom of the waste gas injection well using a drill rod, and a drilling and punching integrated drill tool is provided at the front end of the drill rod. The drilling and punching integrated drill tool is provided with a jet nozzle and a pressure relief chamber is constructed by generating a high-pressure jet to cut the coal body. The bottom of the water-coal lifting well is connected to the pressure relief chamber and is provided with a ground lifting pump.

[0013] Preferably, the equivalent aperture of the pressure relief chamber is 3-6m, which is used to overcome the expansion deformation generated during the injection of high-temperature exhaust gas and increase the injection amount of high-temperature exhaust gas.

[0014] Preferably, a pulse coal breaking device is provided in the pressure relief chamber, and the pulse coal breaking device is used to further break up the large coal blocks generated in the chamber making process to prevent the ground lifting pump from being blocked during the lifting process.

[0015] Preferably, the pressure relief chamber is arranged inclined along the vertical direction of the coal seam, with an inclination angle of 3-10°, which is conducive to slag discharge during the chamber making process.

[0016] Preferably, the portion of the pressure relief chamber connected to the bottom of the gas-water-coal lifting shaft is constructed with a spherical space to facilitate the gathering of water and coal slag.

[0017] The present invention also provides a method for using a closed-loop system for coal mine gas development and utilization and waste gas emission reduction, comprising the following steps:

[0018] S1. First, construct an extraction well from the ground to the target coal seam, and then construct a waste gas injection well and a gas-water-coal lifting well. The bottoms of the waste gas injection well and the gas-water-coal lifting well are connected to each other;

[0019] S2. The water source is provided by the water reservoir, and after being pressurized by the water pump group, it passes through the drill pipe to reach the integrated drilling tool to form a high-pressure water jet to cut the coal body and construct a pressure relief chamber;

[0020] S3. The gas, water and coal slag formed in the process of constructing the pressure relief chamber are gathered at the bottom of the gas-water coal lifting shaft, and then further crushed by the pulse coal crushing device, and then lifted to the ground by the ground lifting pump, and separated in the gas-liquid-solid separator. The generated gas enters the gas storage tank through the extraction pump station, the slaked lime filtrate pool, and the wire mesh filter device, the generated coal slag is stored in the coal bunker, and the generated water enters the water storage tank;

[0021] S4. Start the extraction pump station to extract coal seam gas. The extracted gas passes through the slaked lime filtrate pool and the wire mesh filter device and then enters the gas storage tank;

[0022] S5. The gas in the gas storage tank enters the gas turbine for combustion through the flame arrester and dehydration device. The high-temperature steam generated by the combustion drives the shaft generator to generate electricity;

[0023] S6. The high-temperature exhaust gas generated during the combustion process in the gas turbine is stored in a high-temperature and high-pressure tail gas temporary storage tank group. After being pressurized by a high-temperature gas booster pump group, it is injected into the coal seam through the exhaust gas injection well. The high temperature in the exhaust gas causes micro-cracks in the coal body to increase the gas migration capacity. At the same time, the CO2 and N2 gases in the exhaust gas compete with methane for adsorption, further promoting gas desorption and improving the gas production capacity of the extraction well.

[0024] The beneficial effects of the present invention are as follows: the present invention, based on the characteristics of deep coal and gas resources, constructs a resource development-gas power generation-waste gas emission reduction zero-emission closed-loop system, and uses high-temperature hot exhaust gas generated by coal fire and gas power generation to displace coal seam gas, which not only increases the production of coal seam methane, but also reduces the emission of greenhouse gases in coal mining areas, which plays an important role in building green mines and achieving national carbon neutrality; in addition, since high-temperature exhaust gas injected into coal seams will cause the coal body to expand and deform, the permeability is greatly reduced, and the amount of high-temperature exhaust gas injected is small, in order to overcome this problem, the present invention proposes to provide the coal body with external expansion space through high-pressure water jet cavity creation, so as to prevent the permeability of the coal seam from being reduced due to expansion caused by high temperature and adsorption, which is conducive to increasing the amount of exhaust gas injected. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A structural schematic diagram of a coal mine gas development and utilization and waste gas emission reduction closed-loop system provided in an embodiment of the present invention.

[0027] Description of reference numerals:

[0028] 1-extraction well, 2-waste gas injection well, 3-gas-water-coal lifting well, 4-water reservoir, 5-high-pressure water pump group, 6-drill pipe, 7-drilling and punching integrated drilling tools, 8-pressure relief chamber, 9-pulse coal breaking device, 10-ground lifting pump, 11-gas-liquid-solid separator, 12-coal bunker, 13-extraction pump station, 14-slaked lime filtrate pool, 15-wire mesh filter device, 16-gas storage tank, 17-flame arrester, 18-dehydration device, 19-gas turbine, 20-shaft generator, 21-exhaust temporary storage tank group, 22-gas booster pump group. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] like Figure 1 As shown, a closed-loop system for coal mine gas development and utilization and waste gas emission reduction includes a gas development system, a gas power generation system and a waste gas reinjection system;

[0031] The gas development system includes an extraction pump station 13, a slaked lime filtrate pool 14 for filtering CO2 gas mixed in the extracted gas, a wire mesh filter device 15 for filtering coal powder particles in the extracted gas, and a gas storage tank 16, which are sequentially connected through pipelines. The extraction end of the extraction pump station 13 is connected to the extraction well 1;

[0032] The gas power generation system includes a flame arrester 17, a dehydration device 18, a gas turbine 19, a shaft generator 20 and an exhaust gas temporary storage tank group 21 which are connected together in sequence through pipelines; the flame arrester 17 is connected to the outlet of the gas storage tank 16; the gas turbine 19 is connected to the exhaust gas temporary storage tank group 21, and the high-temperature exhaust gas generated has a temperature in the range of 350-450°C and contains gases such as water vapor, N2, and CO2.

[0033] The exhaust gas reinjection system includes a water pump group 5 connected to a water reservoir 4, a gas booster pump group 22 connected to a tail gas temporary storage tank group 21, and a gas-liquid-solid separator 11. The tail gas temporary storage tank group 21 and the gas booster pump group 22 can withstand a high temperature of 500-800°C.

[0034] The inlet of the gas-liquid-solid separator 11 is connected to the gas-water-coal lifting well 3, and the outlet of the gas-liquid-solid separator 11 is respectively connected to the entrance of the water reservoir 4, the coal bunker 12 and the extraction pump station 13, and the outlets of the water pump group 5 and the gas booster pump group 22 are both connected to the inlet of the waste gas injection well 2;

[0035] A long hole is drilled at the bottom of the waste gas injection well 2 using a drill rod 6, and a drilling and punching integrated drill tool 7 is provided at the front end of the drill rod 6. The drilling and punching integrated drill tool 7 is provided with a jet nozzle and a pressure relief chamber 8 is constructed by generating a high-pressure jet to cut the coal body. The bottom of the water-coal lifting well 3 is connected to the pressure relief chamber 8 and is provided with a ground lifting pump 10.

[0036] The pressure relief chamber 8 has an equivalent aperture of 3-6 m, which is used to overcome the expansion deformation produced during the injection of high-temperature exhaust gas and increase the injection amount of high-temperature exhaust gas.

[0037] A pulse coal breaking device 9 is provided in the pressure relief chamber 8, and the pulse coal breaking device 9 is used to further break up the large coal blocks produced in the chamber making process to prevent the ground lifting pump 10 from being blocked during the lifting process.

[0038] The pressure relief cavity 8 is arranged inclined along the vertical direction of the coal seam, with an inclination of 3-10°, which is beneficial to slag discharge during the cavity making process.

[0039] The portion of the pressure relief chamber 8 connected to the bottom of the gas-water-coal lifting shaft 3 is constructed with a spherical space to facilitate the gathering of water and coal slag.

[0040] The embodiment of the present invention also provides a method for using a closed-loop system for coal mine gas development and utilization and waste gas emission reduction, comprising the following steps:

[0041] S1. First, a pumping well 1 is constructed from the ground to the target coal seam, and then a waste gas injection well 2 and a gas-water-coal lifting well 3 are constructed. The bottoms of the waste gas injection well 2 and the gas-water-coal lifting well 3 are interconnected;

[0042] S2. The water source is provided by the water reservoir 4, and after being pressurized by the water pump group 5, it reaches the integrated drilling and punching drilling tool 7 through the drill pipe 6 to form a high-pressure water jet cutting coal body to construct a pressure relief chamber 8;

[0043] S3. The gas, water and coal slag formed in the process of constructing the pressure relief chamber 8 are gathered at the bottom of the gas-water coal lifting shaft 3, and then further crushed by the pulse coal crushing device 9, and then lifted to the ground by the ground lifting pump 10, and separated in the gas-liquid-solid separator 11. The gas formed enters the gas storage tank 16 through the extraction pump station 13, the slaked lime filtrate pool 14, and the wire mesh filter device 15. The coal slag formed is stored in the coal bunker 12, and the water formed enters the water storage tank 4;

[0044] S4. Start the extraction pump station 13 to start extracting coal seam gas. The extracted gas passes through the slaked lime filtrate pool 14 and the wire mesh filter device 15 and then enters the gas storage tank 16;

[0045] S5. The gas in the gas storage tank 16 enters the gas turbine 19 through the flame arrester 17 and the dehydration device 18 for combustion, and the high-temperature steam formed by the combustion drives the shaft generator 20 to generate electricity;

[0046] S6. The high-temperature exhaust gas generated during the combustion process in the gas turbine 19 is stored in a high-temperature and high-pressure exhaust gas temporary storage tank group 21. After being pressurized by a high-temperature gas booster pump group 22, it is injected into the coal seam through the exhaust gas injection well 2. The high temperature in the exhaust gas causes micro-cracks in the coal body to increase the gas migration capacity. At the same time, the CO2 and N2 gases in the exhaust gas compete with methane for adsorption, further promoting gas desorption and improving the gas production capacity of the extraction well 1.

[0047] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A closed-loop system for coal mine gas development and utilization and waste gas emission reduction, characterized in that: Including gas development system, gas power generation system and exhaust gas reinjection system; The gas development system comprises an extraction pump station (13), a slaked lime filtrate pool (14), a wire mesh filter device (15) and a gas storage tank (16) which are sequentially connected together through pipelines, and the extraction end of the extraction pump station (13) is connected to the extraction well (1); The gas power generation system comprises a flame arrester (17), a dehydration device (18), a gas turbine (19), a shaft generator (20) and a tail gas temporary storage tank group (21) which are sequentially connected together through pipelines; the flame arrester (17) is communicated with the outlet of the gas storage tank (16); The exhaust gas reinjection system comprises a water pump group (5) connected to a water reservoir (4), a gas booster pump group (22) connected to a tail gas temporary storage tank group (21), and a gas-liquid-solid separator (11), wherein the tail gas temporary storage tank group (21) and the gas booster pump group (22) can withstand a high temperature of 500-800°C; The inlet of the gas-liquid-solid separator (11) is connected to the gas-water-coal lifting well (3), the outlet of the gas-liquid-solid separator (11) is respectively connected to the inlet of the water reservoir (4), the coal bunker (12) and the extraction pump station (13), and the outlets of the water pump group (5) and the gas booster pump group (22) are both connected to the inlet of the waste gas injection well (2); The bottom of the waste gas injection well (2) is drilled with a long hole by means of a drill rod (6); the front end of the drill rod (6) is provided with an integrated drilling tool (7); the integrated drilling tool (7) is provided with a jet nozzle and generates a high-pressure jet to cut the coal body to form a pressure relief chamber (8); the bottom of the water-coal lifting well (3) is connected to the pressure relief chamber (8) and is provided with a surface lifting pump (10).

2. A closed-loop system for coal mine gas development and utilization and waste gas emission reduction as claimed in claim 1, characterized in that: The pressure relief chamber (8) has an equivalent aperture of 3-6 m and is used to overcome the expansion deformation generated during the injection of high-temperature exhaust gas and increase the injection amount of high-temperature exhaust gas.

3. A closed-loop system for coal mine gas development and utilization and waste gas emission reduction as claimed in claim 1, characterized in that: A pulse coal breaking device (9) is provided in the pressure relief chamber (8), and the pulse coal breaking device (9) is used to further break up large pieces of coal produced in the chamber making process, thereby preventing the ground lifting pump (10) from being blocked during the lifting process.

4. The method for using a closed-loop system for coal mine gas development and utilization and waste gas emission reduction as claimed in claim 3, characterized in that: The following steps are involved: S1. First, a extraction well (1) is constructed from the ground to the target coal seam, and then a waste gas injection well (2) and a gas-water-coal lifting well (3) are constructed. The bottoms of the waste gas injection well (2) and the gas-water-coal lifting well (3) are interconnected; S2. The water source is provided by the water reservoir (4), and after being pressurized by the water pump group (5), it passes through the drill pipe (6) to reach the integrated drilling tool (7) to form a high-pressure water jet to cut the coal body to construct a pressure relief chamber (8); S3. The gas, water and coal slag formed in the process of constructing the pressure relief chamber (8) are gathered at the bottom of the gas-water coal lifting shaft (3), and then further crushed by the pulse coal crushing device (9), and then lifted to the ground by the ground lifting pump (10), and separated in the gas-liquid-solid separator (11). The generated gas enters the gas storage tank (16) through the extraction pump station (13), the slaked lime filtrate pool (14), and the wire mesh filter device (15). The generated coal slag is stored in the coal bunker (12), and the generated water enters the water storage tank (4); S4. Start the extraction pump station (13) to start extracting coal seam gas. The extracted gas passes through the slaked lime filtrate pool (14) and the wire mesh filter device (15) and then enters the gas storage tank (16); S5. The gas in the gas storage tank (16) enters the gas turbine (19) through the flame arrester (17) and the dehydration device (18) for combustion, and the high-temperature steam formed by the combustion drives the shaft generator (20) to generate electricity; S6. The high-temperature exhaust gas generated during the combustion process in the gas turbine (19) is stored in a high-temperature and high-pressure tail gas temporary storage tank group (21). After being pressurized by a high-temperature gas booster pump group (22), it is injected into the coal seam through the exhaust gas injection well (2). The high temperature in the exhaust gas causes micro-cracks in the coal body to improve the gas migration capacity. At the same time, the CO2 and N2 gases in the exhaust gas compete with methane for adsorption, further promoting gas desorption and improving the gas production capacity of the extraction well (1).

5. The method for using a closed-loop system for coal mine gas development and utilization and waste gas emission reduction as claimed in claim 4, characterized in that: The pressure relief chamber (8) is arranged in an inclined manner along the vertical direction of the coal seam, with an inclination angle of 3-10°, which is conducive to slag discharge during the chamber making process.

6. The method for using a closed-loop system for coal mine gas development and utilization and waste gas emission reduction as claimed in claim 4, characterized in that: The part of the pressure relief chamber (8) connected to the bottom of the gas-water-coal lifting shaft (3) is constructed with a spherical space to facilitate the gathering of water and coal slag.

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