Equipment and method for ring-shaped cavitation and permeability enhancement by supersonic rotating air knife in underground coal mines

Abstract

The present invention relates to the technical field related to enhanced extraction of coal mine gas, and in particular to an annular cavitation and permeability enhancement device and method for supersonic rotary air knife in underground coal mines. The annular cavitation and permeability enhancement method of the supersonic rotary air knife disclosed in the present invention utilizes multi-Mach number supersonic gas formed by medium pressure (5-20MPa) gas accelerated by a Laval nozzle to form an annular air knife during the drill bit rotation and retraction process, and completes the "retreat-advance-retreat" cavitation and permeability enhancement process according to different predetermined pressures, effectively discharges cavitation coal slag and completes cavitation and permeability enhancement, and the present invention also provides a calculation method for the predetermined pressure. The present invention is safe in construction and simple in operation, avoids the problems of hole blocking and gas desorption inhibition easily caused by hydraulic cavitation, and can effectively perform cavitation, permeability enhancement and enhanced extraction on soft coal seams.

Description

Technical Field

[0001] The present invention relates to the technical field related to enhanced extraction of coal mine gas, and is mainly applicable to low-permeability, broken, soft and difficult-to-extract coal seams, and in particular to an annular cavitation and permeability enhancement device and method using a supersonic rotating air knife in underground coal mines. Background Art

[0002] Gas disasters are the most harmful type of coal mine disasters, including coal and gas outbursts, gas explosions and other accidents that have posed a serious threat to my country's coal mine safety production. Gas extraction is the main technical means to control coal mine gas disasters. Affected by the deployment and connection of coal mining, especially for low-permeability, broken and soft coal seams that are difficult to extract, how to extract gas from coal seams within a limited time is the biggest problem that plagues coal mine gas disaster management. The hydraulic cavitation technology uses the connection channel between the drill rod and the drill bit to deliver high-pressure water (pressure 20-100MPa) during the drilling or drilling after the drilling rig is completed, impacting the coal body around the borehole to expand the borehole diameter, artificially creating caves in the coal seam, thereby increasing the effective flow area of ​​gas during the extraction process, and releasing the stress of the coal seam itself and improving the permeability of the coal body during the deformation of the borehole. This method of improving the efficiency of coal seam gas extraction has achieved certain results and has been applied in many mining areas.

[0003] However, the adsorption potential well of water with strong polarity on the coal surface is much larger than that of gas, and it is very easy to form water molecule clusters in the microcracks and macropores of the coal body, blocking the migration of gas, especially the migration channel for the desorbed gas to diffuse outward. In addition, a large amount of liquid water will remain in the lower holes of the downward drilling or cavitation, reducing the effective extraction area of ​​the drilling hole, and it is difficult to be extracted by the extraction negative pressure of the extraction system. Therefore, although hydraulic cavitation can promote the development and growth of some cracks in the early stage, thereby improving the permeability coefficient of the coal body to a certain extent, from a long-term perspective, it has an inhibitory effect on the desorption of gas molecules and is not conducive to quickly reducing the adsorbed gas content in the coal seam. Exploring new water-free cavitation methods is of great significance for increasing the permeability and enhancing extraction of coal seams.

[0004] There are also some related technical documents in the prior art that record the cavitation technology. For example: Patent document (ZL200910172558.7) proposes a reverse circulation aerodynamic cavitation method and equipment for coalbed methane wells, which injects high-pressure air / foam into the coalbed methane well, and then allows the coalbed methane well to blow out and create cavities. Patent document (ZL201510006074.0) proposes a high-pressure abrasive gas jet to break coal, unload pressure and increase permeability. The high-pressure abrasive air jet formed by mixing high-pressure air and abrasive is transported to the nozzle of the drill bit to erode the coal body. Patent document (ZL201910796409.1) proposes a coal seam hole expansion and permeability increase method using pneumatic coupling. First, the first section of the borehole is drilled by drill bit I, and then a drill bit II with an expandable diameter is used to complete the hole expansion and cavitation process by coupling the high-pressure gas and the expansion drill bit to the coal body. The above methods all have the problem of complex equipment or process structure, and on-site construction may be difficult.

[0005] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to those skilled in the art. Summary of the invention

[0006] In view of the problems existing in the existing coal seam cavitation, permeability enhancement and extraction technology, the present invention proposes a device and method for annular cavitation and permeability enhancement using a supersonic gas rotary air knife in a coal mine. The device is simple, easy to operate, and will not cause water blocking and hole clogging, and can effectively expand the hole, increase permeability and enhance extraction of the coal seam.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides an annular cavitation and infiltration enhancement device for a supersonic rotating air knife in a coal mine, which comprises: a drilling rig, a double-channel drill rod for air and water, a supersonic gas jet drill bit, a compressed air filter device, a high-pressure gas compressor, a high-pressure gas storage tank and a gas pressure regulating device;

[0009] The inlet of the high-pressure gas compressor is connected to the compressed air filtering device;

[0010] The high-pressure gas compressor is connected to the inlet of the high-pressure gas storage tank;

[0011] The outlet of the high-pressure gas storage tank is connected to the inlet of the gas pressure regulating device;

[0012] The outlet of the gas pressure regulating device is connected to the inlet of the gas and water conducting dual-channel drill pipe on the drilling rig;

[0013] The air-conducting and water-conducting dual-path drill pipe is connected to the supersonic gas jet drill bit.

[0014] As a further technical solution, the supersonic gas jet drill bit comprises: a drill bit body, a PDC drill bit cutting tool, a water guide nozzle, a supersonic gas Laval nozzle, a water guide passage, an air guide pipeline, an air guide pipeline interface and a drill bit interface;

[0015] The front end of the drill bit body is provided with a PDC drill bit cutting tool and a water guide nozzle;

[0016] A supersonic gas Laval nozzle is provided on the side of the drill bit body;

[0017] A water guide passage and an air guide pipeline are provided inside the drill bit body, the water guide nozzle is connected to the water guide passage, and the supersonic gas Laval nozzle is connected to the air guide pipeline;

[0018] The rear end of the drill body is provided with an air guide pipeline interface and a drill interface.

[0019] As a further technical solution, there are two water guide nozzles and two supersonic gas Laval nozzles.

[0020] As a further technical solution, the air-conducting and water-conducting dual-path drill pipe comprises: a drill pipe body, a drill pipe joint, an air-conducting pipeline, an air-conducting pipeline interface, a fixed retaining ring and a water-conducting passage;

[0021] A water guide passage is provided inside the drill rod body along its length direction;

[0022] An air guide pipe is arranged inside the water guide passage along its length direction;

[0023] The air guide pipeline and the water guide passage are fixed by a fixed retaining ring;

[0024] A drill rod joint is provided at one end of the drill rod body, and a drill rod interface is provided at the other end of the drill rod body;

[0025] When the supersonic gas jet drill bit is connected to the air-conducting and water-conducting dual-path drill pipe, the drill pipe joint of the drill pipe body can be connected to the drill bit interface of the drill bit body, the water-conducting path of the drill pipe body can be connected to the water-conducting path of the drill bit body, and at the same time, the air-conducting pipeline of the drill pipe body can be connected to the air-conducting pipeline of the drill bit body.

[0026] As a further technical solution, a plurality of sections of the air-conducting and water-conducting dual-path drill pipes are connected in sequence and then connected to the supersonic gas jet drill bit.

[0027] As a further technical solution, it also includes: a high-pressure hose; the high-pressure gas compressor is connected to the inlet of the high-pressure gas storage tank through a high-pressure hose, the outlet of the high-pressure gas storage tank is connected to the inlet of the gas pressure regulating device through a high-pressure hose, and the outlet of the gas pressure regulating device is connected to the inlet of the air and water dual-channel drill pipe on the drilling rig through a high-pressure hose.

[0028] In a second aspect, the present invention further provides a method for annular cavitation and permeability enhancement equipment according to the supersonic rotating air knife in a coal mine, which comprises the following steps:

[0029] S1. Drilling is performed using a drilling rig, a gas-conducting and water-conducting dual-channel drill pipe, and a supersonic gas jet drill bit. During the drilling process, the gas-conducting and water-conducting dual-channel drill pipe is connected to a downhole water pipe, and drilling is performed using a water-cooling method. Drilling is stopped after drilling to a predetermined position;

[0030] S2. Connect the downhole compressed air pipeline, compressed air filter, high-pressure gas compressor, high-pressure gas storage tank, gas pressure regulating device and gas and water dual-channel drill pipe in sequence, start the high-pressure gas compressor, and increase the pressure of the high-pressure gas storage tank to 20MPa;

[0031] S3, using a gas pressure regulating device to gradually increase the gas pressure in the supersonic gas jet drill bit to pressure level I, using the supersonic gas Laval nozzle on the drill bit to accelerate the high-pressure gas to form a supersonic air knife, start the first cavitation, use the drill rig to rotate and withdraw the drill, form a supersonic annular air knife to crush the coal body, until the drill bit retreats to a predetermined cavitation distance;

[0032] S4, gradually increase the gas pressure to pressure level II, use the drill to rotate and drill, further expand the hole size, and avoid excessive coal body crushing in one hole making, which may cause blockage of the borehole, until the drill bit moves to the starting hole making position in step S3;

[0033] S5, gradually increasing the gas pressure to a predetermined maximum pressure level III, and using the drilling rig to rotate and retract the drill until the drill bit retracts to the predetermined position in step S3;

[0034] S6, using a gas pressure regulating device to close the gas inlet, using a drill to rotate and withdraw the drill to the predetermined position of the second cavitation, repeating steps S3 to S5 to complete the second cavitation and permeation enhancement;

[0035] S7. Repeat step S6 until a predetermined number of segmented cavitation and infiltration enhancement operations are completed.

[0036] As a further technical solution, the predetermined pressure level III satisfies the following formula:

[0037]

[0038] Where a is a parameter related to the predetermined pressure level III, i.e. P P * is the gas pressure in the stagnant state, H is the desired cavitation radius, b 0 is the nozzle outlet cross-sectional area, T is the gas thermodynamic temperature, S t represents the nozzle throat area, ρ is the air density, and v is the Poisson's ratio of the cavitation coal body.

[0039] As a further technical solution, the pressure level I is 1 / 2 of the pressure level III; the pressure level II is 3 / 4 of the pressure level III.

[0040] By adopting the above technical solution, the present invention has the following beneficial effects:

[0041] Compared with the prior art, the technology proposed by the present invention introduces the Laval acceleration nozzle and supersonic gas propulsion concepts of rocket engines in the aviation field into the field of coal seam cavitation, permeability enhancement and gas enhanced extraction. It uses the multi-Mach number supersonic gas formed by the acceleration of medium-pressure (5-20MPa) gas through the Laval nozzle to form an annular gas knife during the drill bit withdrawal process, which cuts the coal body around the borehole and forms a pressure relief cave with a larger diameter. Then, under the action of ground stress, the elastic potential and gas expansion energy in the coal body are released, and gas extraction is enhanced safely and efficiently. At the same time, because the gas pressure used is moderate, the technology proposed by the present invention will not cause large formation stress disturbances, damage the top and bottom plates of the coal seams, or induce protrusions during the construction process, which can ensure technical safety and construction safety, and has great application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 It is a schematic diagram of the supersonic rotating air knife annular cavitation and infiltration enhancement device in the present invention;

[0044] Figure 2 is a cross-sectional view of a supersonic gas jet drill bit in the present invention;

[0045] Figure 3 This is a planed surface diagram of the air-conducting and water-conducting dual-path drill pipe in the present invention;

[0046] Figure 4 It is a schematic diagram of the process of accelerating gas to supersonic speed by the Laval nozzle in the present invention.

[0047] Figure 5 It is a schematic diagram of the annular segmented cavitation and infiltration enhancement effect of the supersonic rotating air knife in the present invention.

[0048] Figure 1 In the figure: 1 is a drilling rig, 2 is an underground tunnel in a coal mine, 3 is an underground water pipeline in a coal mine, 4 is a target coal seam for cave making, 5 is a double-channel drill rod for air and water conduction, 6 is a supersonic gas jet drill bit, 7 is an underground compressed air pipeline in a coal mine, 8 is a compressed air filtering device, 9 is a high-pressure rubber hose, 10 is a high-pressure gas compressor, 11 is a high-pressure gas storage tank, 111 is an air inlet of a high-pressure gas storage tank, 112 is an air outlet of a high-pressure gas storage tank, 113 is a sewage relief valve of a high-pressure gas storage tank, 114 is a pressure gauge, 12 is a gas pressure regulating device, 121 is a high-pressure ball valve, and 122 is a gas pressure regulating valve.

[0049] Figure 2 Middle: 61 is a PDC drill bit cutting tool, 62 is a water guide nozzle, 63 is a supersonic gas Laval nozzle, 64 is a water guide passage, 65 is a gas guide pipeline, 66 is a gas guide pipeline interface, and 67 is a drill bit interface.

[0050] Figure 3 In the middle: 51 is a drill pipe joint, 52 is an air guide pipe, 53 is an air guide pipe interface, 54 is a fixed retaining ring, 55 is a water guide passage; 56 is a water guide high-pressure hose; 57 is an air guide high-pressure hose. DETAILED DESCRIPTION

[0051] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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.

[0052] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0053] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0054] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0055] Embodiment 1

[0056] Combination Figures 1 to 5 As shown, the present invention provides a coal mine underground supersonic rotating air knife annular cavitation and infiltration enhancement equipment, which includes: a drilling machine 1, a gas and water dual-channel drill rod 5, a supersonic gas jet drill bit 6, a compressed air filter device 8, a high-pressure gas compressor 10, a high-pressure gas storage tank 11 and a gas pressure regulating device 12;

[0057] The inlet of the high-pressure gas compressor 10 is connected to the compressed air filtering device 8;

[0058] The high-pressure gas compressor 10 is connected to the inlet of the high-pressure gas storage tank 11;

[0059] The outlet of the high-pressure gas storage tank 11 is connected to the inlet of the gas pressure regulating device 12;

[0060] The outlet of the gas pressure regulating device 12 is connected to the inlet of the gas and water conducting dual-channel drill pipe 5 on the drilling rig, and a high-pressure ball valve 121 and a gas pressure regulating valve 122 are installed at the outlet of the gas pressure regulating device, and the two are in a series relationship;

[0061] The air-conducting and water-conducting dual-path drill pipe 5 is connected to the supersonic gas jet drill bit 6 .

[0062] As a further technical solution, the supersonic gas jet drill bit 6 comprises: a drill bit body, a PDC drill bit cutting tool 61, a water guide nozzle 62, a supersonic gas Laval nozzle 63, a water guide passage, an air guide pipeline, an air guide pipeline interface 66 and a drill bit interface 67;

[0063] The front end of the drill bit body is provided with a PDC drill bit cutting tool 61 and a water guide nozzle 62;

[0064] A supersonic gas Laval nozzle is provided on the side of the drill bit body;

[0065] A water guide passage and an air guide pipeline are provided inside the drill bit body, the water guide nozzle is connected to the water guide passage, and the supersonic gas Laval nozzle is connected to the air guide pipeline;

[0066] The rear end of the drill body is provided with an air pipe interface 66 and a drill interface 67 .

[0067] As a further technical solution, there are two water guide nozzles and two supersonic gas Laval nozzles 63 .

[0068] As a further technical solution, the air-conducting and water-conducting dual-path drill rod 5 comprises: a drill rod body, a drill rod joint 51, an air-conducting pipeline 52, an air-conducting pipeline interface 53, a fixed retaining ring 54 and a water-conducting passage 55. The air-conducting and water-conducting dual-path drill rod 55 is connected to the underground water pipeline 3 of the coal mine through a water-conducting high-pressure hose 56, and is connected to the outlet of the gas pressure regulating device 12 through a gas-conducting high-pressure hose 57;

[0069] A water guide passage 55 is provided inside the drill rod body along its length direction;

[0070] The water conduit 55 is provided with an air conduit 52 along its length.

[0071] The air guide pipe 52 and the water guide passage 55 are fixed by a fixed retaining ring 54;

[0072] A drill rod joint 51 is provided at one end of the drill rod body, and a drill rod interface is provided at the other end of the drill rod body;

[0073] When the supersonic gas jet drill bit 6 is connected to the air-conducting and water-conducting dual-path drill pipe 5, the drill pipe joint 51 of the drill pipe body can be connected to the drill bit interface 67 of the drill bit body, the water-conducting path of the drill pipe body can be connected to the water-conducting path of the drill bit body, and at the same time, the air-conducting pipeline of the drill pipe body can be connected to the air-conducting pipeline of the drill bit body.

[0074] As a further technical solution, a plurality of sections of the air-conducting and water-conducting dual-path drill pipe 5 are connected in sequence and then connected to the supersonic gas jet drill bit 6 .

[0075] As a further technical solution, it also includes: a high-pressure hose 9; the high-pressure gas compressor 10 is connected to the inlet of the high-pressure gas storage tank through the high-pressure hose 9, the outlet of the high-pressure gas storage tank is connected to the inlet of the gas pressure regulating device through the high-pressure hose 9, and the outlet of the gas pressure regulating device is connected to the inlet of the gas and water-guiding dual-channel drill pipe 5 on the drilling rig through the high-pressure hose 9.

[0076] Embodiment 2

[0077] This embodiment provides a method for using a supersonic rotating air knife to perform annular cavitation and increase infiltration in an underground coal mine.

[0078] 1) If Figure 1 As shown, first, the drilling machine 1 is transported to the underground tunnel 2 of the coal mine at the construction site, and the underground water pipeline 3 of the coal mine is connected to the drilling machine 1. Conventional water-cooled drilling construction is performed on the target coal seam 4 for cavitation. However, the drilling tool adopts a double-channel drill rod 5 for air and water and a supersonic gas jet drill bit 6. In this process, Figure 2 As shown, the air-conducting and water-conducting dual-path drill pipe 5 is connected to the underground water pipeline 3 of the coal mine through the water-conducting high-pressure hose 56, and the air-conducting joint 55 is blocked with a nut. The pressurized water in the underground water pipeline 3 of the coal mine flows to the supersonic gas jet drill bit 6 through the water-conducting passage 55 in the air-conducting and water-conducting dual-path drill pipe 5. Figure 3 As shown, the water is sprayed out through the water guide nozzle 62 to achieve the purpose of cooling during the drilling process, and the drilling is stopped after the preset depth is reached.

[0079] 2) While the drilling rig is drilling, the downhole compressed air pipeline 7 is connected to the inlet of the compressed air filter device 8, and the outlet of the compressed air filter device 8 is connected to the inlet of the high-pressure gas compressor 10 by a high-pressure rubber hose 9. The outlet of the high-pressure gas compressor 10 is connected to the air inlet 111 of the high-pressure gas storage tank, and the air outlet 112 of the high-pressure gas storage tank is connected to the gas pressure regulating device 12. The high-pressure ball valve 121 and the gas pressure regulating valve 122 are closed, and the high-pressure gas compressor 10 is turned on to inflate the high-pressure gas storage tank until the pressure of the pressure gauge 114 rises to 20MPa (the specific form of the high-pressure gas storage tank is not limited, and a high-pressure gas storage tank sewage discharge pressure relief valve 113 may be provided).

[0080] 3) After step 1 is completed, the water-conducting high-pressure hose 56 connecting the downhole water pipeline 3 and the air-conducting and water-conducting dual-path drill pipe 5 is removed, and the outlet of the gas pressure regulating device is connected to the gas-conducting pipeline 55 of the air-conducting and water-conducting dual-path drill pipe 5 by using the gas-conducting high-pressure hose 57, and the high-pressure gas is delivered to the supersonic gas Laval nozzle 63 through the gas-conducting pipeline 55 in the air-conducting and water-conducting dual-path drill pipe 5 and the gas-conducting pipeline interface 66 in the supersonic gas jet drill bit 6, and the gas pressure is adjusted to a predetermined pressure level I by using the gas pressure regulating valve 122, such as Figure 4 As shown, the supersonic gas Laval nozzle 63 on the drill bit is used to accelerate the high-pressure gas, and the supersonic gas will be accelerated to a Mach number of 2-5, forming a huge impact force within the target distance range, that is, a supersonic air knife, starting the first cavitation, and the drill rig 1 is used to rotate and slowly withdraw the drill. During the rotation process, a supersonic annular air knife is formed to crush the coal body until the drill bit 6 retreats to a predetermined cavitation distance, which is equal to a predetermined cavitation length.

[0081] The predetermined pressure level I is 1 / 2 of the predetermined pressure level III (P). The predetermined pressure level III is calculated by formula 1:

[0082]

[0083] Where a is a parameter related to the predetermined pressure level, i.e., P P * is the gas pressure in the stagnant state, H is the desired cavitation radius, b 0 is the nozzle outlet cross-sectional area, T is the gas thermodynamic temperature, S t represents the nozzle throat area, ρ is the air density, and v is the Poisson's ratio of the cavitation coal body.

[0084] The Poisson's ratio of cavitation coal can be determined by laboratory experiments.

[0085] 4) The gas pressure regulating valve 122 is used to adjust the gas pressure to a predetermined pressure level II, and the drilling rig 1 is used to rotate and slowly advance the drilling to further expand the hole size, while avoiding excessive coal body crushing in one hole making to cause blockage of the drill hole, until the drill bit 6 advances to the starting hole making position in step 3, and the predetermined pressure level II is 3 / 4 of the predetermined pressure level III (P);

[0086] 5) The gas pressure regulating valve 122 is used to adjust the gas pressure to the predetermined pressure level III, and the drilling rig 1 is used to rotate and retract the drill until the drill bit 6 retreats to the predetermined position in step 3, completing the current hole making process, estimating the coal output at the borehole mouth during the hole making process, comparing the actual coal output with the expected coal output, and evaluating the effect of this hole making. The expected coal output can be calculated by the expected hole making radius H and the predetermined hole making length;

[0087] 6) Close the high-pressure ball valve 121 and the gas pressure regulating valve 122, use the drill rig 1 to rotate and retract the drill to the predetermined position of the second cavitation, repeat steps 3-5, and complete the second cavitation and permeation enhancement;

[0088] 7) Repeat step 6 until the predetermined number of segmented cavitation and infiltration enhancement is completed, and then use the drilling rig 1 to withdraw the drill. Figure 5 As shown, the whole process of drilling, hole making and infiltration enhancement is completed, and the borehole is connected to the extraction system to carry out extraction operations.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A coal mine underground supersonic rotating air knife for annular cavitation and permeability enhancement equipment, characterized in that: include: Drilling rig, air-conducting and water-conducting dual-channel drill pipe, supersonic gas jet drill bit, compressed air filter device, high-pressure gas compressor, high-pressure gas storage tank and gas pressure regulating device; The inlet of the high-pressure gas compressor is connected to the compressed air filtering device; The outlet of the high-pressure gas compressor is connected to the inlet of the high-pressure gas storage tank; The outlet of the high-pressure gas storage tank is connected to the inlet of the gas pressure regulating device; The outlet of the gas pressure regulating device is connected to the inlet of the gas and water conducting dual-channel drill pipe on the drilling rig; The air-conducting and water-conducting dual-path drill pipe is connected to the supersonic gas jet drill bit; The supersonic gas jet drill bit comprises: a drill bit body, a PDC drill bit cutting tool, a water guide nozzle, a supersonic gas Laval nozzle, a water guide passage, an air guide pipeline, an air guide pipeline interface and a drill bit interface; The front end of the drill bit body is provided with a PDC drill bit cutting tool and a water guide nozzle; A supersonic gas Laval nozzle is provided on the side of the drill bit body; The water guide passage and the air guide pipeline are arranged inside the drill bit body, the water guide nozzle is communicated with the water guide passage, and the supersonic gas Laval nozzle is communicated with the air guide pipeline; The tail end of the drill body is provided with an air guide pipe interface and a drill interface; The air-conducting and water-conducting dual-path drill pipe comprises: a drill pipe body, a drill pipe joint, an air-conducting pipeline, an air-conducting pipeline interface, a fixed retaining ring and a water-conducting passage; The inside of the drill rod body is provided with a water guide passage of the double-path drill rod for guiding air and water along its length direction; the inside of the water guide passage of the drill rod body is provided with an air guide pipeline of the double-path drill rod for guiding air and water along its length direction; the air guide pipeline of the drill rod body and the water guide passage are fixed by a fixed retaining ring A drill rod joint is provided at one end of the drill rod body, and a drill rod interface is provided at the other end of the drill rod body; When the supersonic gas jet drill bit is connected to the air-conducting and water-conducting dual-path drill pipe, the drill pipe joint of the drill pipe body can be connected to the drill bit interface of the drill bit body, the water-conducting path of the drill pipe body can be connected to the water-conducting path of the drill bit body, and at the same time, the air-conducting pipeline of the drill pipe body can be connected to the air-conducting pipeline of the drill bit body.

2. The annular cavitation and permeability enhancement equipment for underground coal mine supersonic rotating air knife according to claim 1 is characterized in that: There are two water guide nozzles and two supersonic gas Laval nozzles.

3. The annular cavitation and permeability enhancement equipment for underground coal mine supersonic rotating air knife according to claim 1 is characterized in that: A plurality of sections of the gas-conducting and water-conducting dual-path drill pipes are connected in sequence and then connected to the supersonic gas jet drill bit.

4. The annular cavitation and permeability enhancement equipment for underground coal mine supersonic rotating air knife according to claim 1 is characterized in that: Also includes: High pressure hose; The high-pressure gas compressor is connected to the inlet of the high-pressure gas storage tank through a high-pressure hose, the outlet of the high-pressure gas storage tank is connected to the inlet of the gas pressure regulating device through a high-pressure hose, and the outlet of the gas pressure regulating device is connected to the inlet of the air and water dual-channel drill pipe on the drilling rig through a high-pressure hose.

5. A method for implementing the annular cavitation and permeability enhancement equipment of the supersonic rotating air knife in a coal mine according to any one of claims 1 to 4, characterized in that: The steps include: S1. Drilling is performed using a drilling rig, a gas-conducting and water-conducting dual-channel drill pipe, and a supersonic gas jet drill bit. During the drilling process, the gas-conducting and water-conducting dual-channel drill pipe is connected to a downhole water pipe, and drilling is performed using a water-cooling method. Drilling is stopped after drilling to a predetermined position; S2. Connect the downhole compressed air pipeline, compressed air filter, high-pressure gas compressor, high-pressure gas storage tank, gas pressure regulating device and gas and water dual-channel drill pipe in sequence, start the high-pressure gas compressor, and increase the pressure of the high-pressure gas storage tank to 20MPa; S3, using a gas pressure regulating device to gradually increase the gas pressure in the supersonic gas jet drill bit to pressure level I, using the supersonic gas Laval nozzle on the drill bit to accelerate the high-pressure gas to form a supersonic air knife, start the first cavitation, use the drill rig to rotate and withdraw the drill, form a supersonic annular air knife to crush the coal body, until the drill bit retreats to a predetermined cavitation distance; S4. Gradually increase the gas pressure to pressure level II, use the drill to rotate and drill, further expand the hole size, and avoid excessive coal body crushing in one hole making, which may cause blockage of the borehole, until the drill bit moves to the starting hole making position in the first hole making; S5, gradually increasing the gas pressure to a predetermined maximum pressure level III, and using a drilling rig to rotate and retract the drill until the drill bit retracts to a predetermined position in the first cavitation; S6, using a gas pressure regulating device to close the gas inlet, using a drill to rotate and withdraw the drill to the predetermined position of the second cavitation, repeating steps S3 to S5 to complete the second cavitation and permeation enhancement; S7. Repeat step S6 until a predetermined number of segmented cavitation and infiltration enhancement operations are completed.

6. The implementation method according to claim 5, characterized in that: The predetermined maximum pressure level III satisfies the following formula: 。 7. The implementation method according to claim 6, characterized in that: The pressure level I is 1 / 2 of the predetermined maximum pressure level III; The pressure level II is 3 / 4 of the predetermined maximum pressure level III.

Images