阅读说明：本技术 低透难解吸煤层爆破与注气联合增强瓦斯抽采装置及方法 (Low-permeability and difficult-desorption coal seam blasting and gas injection combined enhanced gas extraction device and method ) 是由 范超军 文海欧 梁冰 李胜 杨振华 杨雷 于 2021-10-11 设计创作，主要内容包括：一种低透难解吸煤层爆破与注气联合增强瓦斯抽采装置及方法,装置的孔内组件包括PDC钻头、钻杆、螺旋叶片及爆破增透堵头；钻头和堵头位于钻杆两端,堵头外侧设有封孔囊袋；螺旋叶片设在钻杆表面；钻杆上设有若干燃爆控制器；孔外组件包括燃爆混合气供给机构和智能点火控制柜；燃爆控制器外接燃爆混合气输入管和燃爆点火导线,二者密封穿过爆破增透堵头后接入与燃爆混合气供给机构相连的控制柜。方法为：利用孔内组件打完平行孔后留置钻孔内并封孔；制备燃爆混合气,通过燃爆混合气输入管和燃爆控制器注入钻孔内；注气结束后启动燃爆控制器进行点火,引爆混合气利用爆炸冲击制造裂隙；移除孔内组件,安装瓦斯抽采管和二氧化碳注气管,进行瓦斯抽采。(A low-permeability and difficult-desorption coal seam blasting and gas injection combined enhanced gas extraction device and a method thereof are disclosed, wherein components in a hole of the device comprise a PDC drill bit, a drill rod, a helical blade and a blasting permeability-increasing plug; the drill bit and the plug are positioned at two ends of the drill rod, and a hole sealing bag is arranged outside the plug; the helical blade is arranged on the surface of the drill rod; a plurality of blasting controllers are arranged on the drill rod; the out-of-hole component comprises a burning and blasting mixed gas supply mechanism and an intelligent ignition control cabinet; the blasting controller is externally connected with a blasting mixed gas input pipe and a blasting ignition lead, and the blasting mixed gas input pipe and the blasting ignition lead are connected into a control cabinet connected with a blasting mixed gas supply mechanism after penetrating through a blasting anti-reflection plug in a sealing manner. The method comprises the following steps: after the parallel holes are punched by the in-hole assembly, reserving the drill holes and sealing the holes; preparing a blasting mixed gas, and injecting the blasting mixed gas into the drill hole through a blasting mixed gas input pipe and a blasting controller; after gas injection is finished, starting a blasting controller to ignite, and blasting mixed gas to manufacture cracks by using explosive impact; and removing the assemblies in the holes, and installing a gas extraction pipe and a carbon dioxide gas injection pipe to extract gas.)

1. The utility model provides a low difficult desorption coal seam blasting and gas injection jointly strengthen gas drainage device which characterized in that: comprises an in-hole component and an out-hole component; the components in the hole comprise a PDC drill bit, a drill rod, a helical blade and a blasting permeability-increasing plug; the PDC drill bit is arranged at the bottom end of the drill rod, and the blasting permeability-increasing plug is arranged at the top end of the drill rod and is positioned at a drilling hole; an inflatable hole sealing bag is sleeved outside the blasting anti-reflection plug; the helical blade is arranged on the surface of the rod body of the drill rod; a plurality of blasting controllers are arranged on the surface of the rod body of the drill rod, and each blasting controller is externally connected with a blasting mixed gas input pipe and a blasting ignition lead; the assembly outside the hole comprises a burning and blasting mixed gas supply mechanism and an intelligent ignition control cabinet, and a burning and blasting mixed gas control valve group is also arranged in the intelligent ignition control cabinet; the blasting ignition lead penetrates through the blasting anti-reflection plug in a sealing manner and is connected with the intelligent ignition control cabinet; the blasting mixed gas input pipe penetrates through the blasting permeability-increasing plug in a sealing mode to be connected with the gas outlet end of a blasting mixed gas control valve group in the intelligent ignition control cabinet, and the gas inlet end of the blasting mixed gas control valve group is connected with a blasting mixed gas supply mechanism.

2. The low-permeability and difficult-desorption coal seam blasting and gas injection combined enhanced gas extraction device according to claim 1, which is characterized in that: the explosion controllers are positioned between two adjacent helical blades, a 90-degree phase angle is formed between the two adjacent explosion controllers, and all the explosion controllers are distributed on the rod body of the drill rod in a helical state space.

3. The low-permeability and difficult-desorption coal seam blasting and gas injection combined enhanced gas extraction device according to claim 1, which is characterized in that: the explosion controller comprises an ignition electrode, an explosion mixed gas jet hole, a jet hole sealing plate, a sealing plate supporting guide rod, a sealing plate supporting guide hole, a sealing plate reset spring, a spring positioning plate and a three-way pipe; an ignition electrode mounting hole is formed in the drill rod body, and the ignition electrode is positioned in the ignition electrode mounting hole; the number of the combustion and explosion mixed gas jet holes is two, and the two jet holes are symmetrically distributed on two sides of the ignition electrode; the sealing plate support guide hole is positioned on the outer side of the blasting mixed gas jet hole, the jet hole sealing plate is positioned on the outlet side of the blasting mixed gas jet hole, the sealing plate support guide rod is positioned in the sealing plate support guide hole, and one end of the sealing plate support guide rod is fixedly connected with the jet hole sealing plate; the other end of the sealing plate reset spring is fixedly connected with one end of the sealing plate reset spring, and the other end of the sealing plate reset spring is fixedly connected with the drill rod body through a spring positioning plate; the inlet sides of the two blasting mixed gas injection holes are communicated with a blasting mixed gas input pipe through a three-way pipe; the ignition electrode is connected with a blasting ignition lead.

4. The low-permeability and difficult-desorption coal seam blasting and gas injection combined enhanced gas extraction device according to claim 1, which is characterized in that: the blasting mixed gas supply mechanism comprises a gas storage tank, a gas-air mixing tank, a blasting mixed gas storage tank and a booster pump; the gas outlet of the gas storage tank is communicated with the gas inlet of the gas-air mixing tank, and a first stop valve is arranged on a pipeline between the gas outlet of the gas storage tank and the gas inlet of the gas-air mixing tank; an air inlet of the gas-air mixing tank is communicated with a dry air supply source, and a second stop valve is arranged on a pipeline between the gas inlet and the dry air supply source; a mixed gas outlet of the gas-air mixing tank is communicated with an air inlet of the combustion and explosion mixed gas storage tank, and a third stop valve is arranged on a pipeline between the gas outlet and the air inlet; the gas outlet of the combustion and explosion mixed gas storage tank is communicated with the gas inlet of the booster pump, and a fourth stop valve is arranged on a pipeline between the gas outlet of the combustion and explosion mixed gas storage tank and the gas inlet of the booster pump; the gas outlet of booster pump and the mixed air control valve group's of blasting in the intelligent ignition switch board inlet end communicate, are equipped with fifth stop valve and check valve on the pipeline between the two in proper order, and the gas outlet of check valve and the mixed air control valve group's of blasting in the intelligent ignition switch board inlet end communicate.

5. A low permeability and difficult desorption coal seam blasting and gas injection combined enhanced gas extraction method adopts the low permeability and difficult desorption coal seam blasting and gas injection combined enhanced gas extraction device of claim 1, and is characterized by comprising the following steps:

the method comprises the following steps: selecting a gas extraction area of a coal seam, setting a drilling position in the selected area, adopting a parallel drilling method, completing drilling operation of a drilled hole by an in-hole assembly consisting of a PDC drill bit, a drill rod, a helical blade and a blasting anti-reflection plug, remaining the in-hole assembly in the drilled hole after drilling is finished, and then completing hole sealing of the drilled hole by inflating an inflatable hole sealing bag;

step two: opening a first stop valve, injecting gas into the gas-air mixing tank through a gas storage tank, simultaneously opening a second stop valve, injecting dry air into the gas-air mixing tank through a dry air supply source until the gas concentration of the gas-air mixing tank reaches a set value and forming combustion and explosion mixed gas, and then closing the first stop valve and the second stop valve;

step three: opening a third stop valve, injecting the mixed combustion and explosion mixed gas into the combustion and explosion mixed gas storage tank until the combustion and explosion mixed gas is filled in the combustion and explosion mixed gas storage tank, and then closing the third stop valve;

step four: opening a fourth stop valve, a fifth stop valve and a combustion and explosion mixed gas control valve group in the intelligent ignition control cabinet, simultaneously starting a booster pump, injecting combustion and explosion mixed gas in a combustion and explosion mixed gas storage tank into a combustion and explosion mixed gas jet hole of a combustion and explosion controller through a combustion and explosion mixed gas input pipe, jacking a jet hole sealing plate under the action of pressure difference to enable a sealing plate reset spring to be in an extension state, continuously filling high-pressure combustion and explosion mixed gas into a drill hole, and when the pressure difference between the combustion and explosion mixed gas jet hole and the drill hole is reduced to be insufficient to overcome the spring force of the sealing plate reset spring, enabling the jet hole sealing plate to be closed again under the action of the spring force of the sealing plate reset spring, closing the booster pump, and simultaneously closing the fourth stop valve, the fifth stop valve and the combustion and explosion mixed gas control valve group in the intelligent ignition control cabinet;

step five: controlling an ignition electrode to generate electric sparks through an intelligent ignition control cabinet, detonating combustion and explosion mixed gas in a drill hole by using the electric sparks, enabling a coal seam around the drill hole to generate cracks under the action of explosion impact, and enabling adjacent drill holes to be communicated through the cracks;

step six: removing the drill holes from the components in the holes, then alternately inserting gas extraction pipes and carbon dioxide gas injection pipes into the plurality of drill holes, installing gas extraction plugs at the hole openings of all the drill holes, enabling the gas extraction pipes and the carbon dioxide gas injection pipes to hermetically penetrate through the gas extraction plugs, sleeving inflatable hole sealing bags outside the gas extraction plugs, and filling air into the inflatable hole sealing bags to complete hole sealing of the drill holes;

step seven: the method comprises the steps of connecting a gas extraction pipe into negative-pressure gas extraction equipment in a mine, connecting a carbon dioxide gas injection pipe into carbon dioxide gas supply equipment in the mine, starting the negative-pressure gas extraction equipment and the carbon dioxide gas supply equipment, injecting carbon dioxide gas into corresponding drill holes through the carbon dioxide gas injection pipe, enabling the carbon dioxide gas to enter peripheral cracks from the drill holes to be used for displacing gas in a coal seam, enabling the displaced gas to enter the drill holes for gas extraction through the cracks, and finally discharging the gas through the gas extraction pipe to achieve gas extraction.

Technical Field

The invention belongs to the technical field of coal rock permeability-increasing gas extraction, and particularly relates to a low-permeability and difficult-desorption coal bed blasting and gas injection combined enhanced gas extraction device and method.

Background

At present, with the increasing of energy demand, the coal mining depth is also increased continuously, deep coal rock is in a high ground stress environment for a long time, the permeability is generally low, the difficulty of gas extraction under the deep mining condition is increased, and the problem of gas outburst becomes an important factor for restricting the production safety of mines.

Conventional gas extraction technologies comprise a hydraulic fracturing technology, a pressure relief extraction technology, a deep space blasting technology and the like, and the conventional gas extraction technologies generally have the defects of large engineering quantity, low efficiency, poor safety and great influence on the environment.

In addition, when conventional coal rock permeability-increasing gas extraction is carried out, drilling is carried out firstly in the conventional operation mode, then drilling equipment is removed, then coal rock permeability increasing is carried out, and finally conventional gas extraction is carried out.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a low-permeability and difficult-desorption coal seam blasting and gas injection combined enhanced gas extraction device and method. The method can effectively increase the crack development degree of the low-permeability and difficult-desorption coal seam, further enhance the gas extraction effect and effectively reduce the gas outburst and gas explosion risks.

In order to achieve the purpose, the invention adopts the following technical scheme: a low-permeability and difficult-desorption coal seam blasting and gas injection combined enhanced gas extraction device comprises an in-hole assembly and an out-hole assembly; the components in the hole comprise a PDC drill bit, a drill rod, a helical blade and a blasting permeability-increasing plug; the PDC drill bit is arranged at the bottom end of the drill rod, and the blasting permeability-increasing plug is arranged at the top end of the drill rod and is positioned at a drilling hole; an inflatable hole sealing bag is sleeved outside the blasting anti-reflection plug; the helical blade is arranged on the surface of the rod body of the drill rod; a plurality of blasting controllers are arranged on the surface of the rod body of the drill rod, and each blasting controller is externally connected with a blasting mixed gas input pipe and a blasting ignition lead; the assembly outside the hole comprises a burning and blasting mixed gas supply mechanism and an intelligent ignition control cabinet, and a burning and blasting mixed gas control valve group is also arranged in the intelligent ignition control cabinet; the blasting ignition lead penetrates through the blasting anti-reflection plug in a sealing manner and is connected with the intelligent ignition control cabinet; the blasting mixed gas input pipe penetrates through the blasting permeability-increasing plug in a sealing mode to be connected with the gas outlet end of a blasting mixed gas control valve group in the intelligent ignition control cabinet, and the gas inlet end of the blasting mixed gas control valve group is connected with a blasting mixed gas supply mechanism.

The explosion controllers are positioned between two adjacent helical blades, a 90-degree phase angle is formed between the two adjacent explosion controllers, and all the explosion controllers are distributed on the rod body of the drill rod in a helical state space.

The explosion controller comprises an ignition electrode, an explosion mixed gas jet hole, a jet hole sealing plate, a sealing plate supporting guide rod, a sealing plate supporting guide hole, a sealing plate reset spring, a spring positioning plate and a three-way pipe; an ignition electrode mounting hole is formed in the drill rod body, and the ignition electrode is positioned in the ignition electrode mounting hole; the number of the combustion and explosion mixed gas jet holes is two, and the two jet holes are symmetrically distributed on two sides of the ignition electrode; the sealing plate support guide hole is positioned on the outer side of the blasting mixed gas jet hole, the jet hole sealing plate is positioned on the outlet side of the blasting mixed gas jet hole, the sealing plate support guide rod is positioned in the sealing plate support guide hole, and one end of the sealing plate support guide rod is fixedly connected with the jet hole sealing plate; the other end of the sealing plate reset spring is fixedly connected with one end of the sealing plate reset spring, and the other end of the sealing plate reset spring is fixedly connected with the drill rod body through a spring positioning plate; the inlet sides of the two blasting mixed gas injection holes are communicated with a blasting mixed gas input pipe through a three-way pipe; the ignition electrode is connected with a blasting ignition lead.

The blasting mixed gas supply mechanism comprises a gas storage tank, a gas-air mixing tank, a blasting mixed gas storage tank and a booster pump; the gas outlet of the gas storage tank is communicated with the gas inlet of the gas-air mixing tank, and a first stop valve is arranged on a pipeline between the gas outlet of the gas storage tank and the gas inlet of the gas-air mixing tank; an air inlet of the gas-air mixing tank is communicated with a dry air supply source, and a second stop valve is arranged on a pipeline between the gas inlet and the dry air supply source; a mixed gas outlet of the gas-air mixing tank is communicated with an air inlet of the combustion and explosion mixed gas storage tank, and a third stop valve is arranged on a pipeline between the gas outlet and the air inlet; the gas outlet of the combustion and explosion mixed gas storage tank is communicated with the gas inlet of the booster pump, and a fourth stop valve is arranged on a pipeline between the gas outlet of the combustion and explosion mixed gas storage tank and the gas inlet of the booster pump; the gas outlet of booster pump and the mixed air control valve group's of blasting in the intelligent ignition switch board inlet end communicate, are equipped with fifth stop valve and check valve on the pipeline between the two in proper order, and the gas outlet of check valve and the mixed air control valve group's of blasting in the intelligent ignition switch board inlet end communicate.

A low permeability and difficult desorption coal bed blasting and gas injection combined enhanced gas extraction method adopts the low permeability and difficult desorption coal bed blasting and gas injection combined enhanced gas extraction device and comprises the following steps:

the method comprises the following steps: selecting a gas extraction area of a coal seam, setting a drilling position in the selected area, adopting a parallel drilling method, completing drilling operation of a drilled hole by an in-hole assembly consisting of a PDC drill bit, a drill rod, a helical blade and a blasting anti-reflection plug, remaining the in-hole assembly in the drilled hole after drilling is finished, and then completing hole sealing of the drilled hole by inflating an inflatable hole sealing bag;

step two: opening a first stop valve, injecting gas into the gas-air mixing tank through a gas storage tank, simultaneously opening a second stop valve, injecting dry air into the gas-air mixing tank through a dry air supply source until the gas concentration of the gas-air mixing tank reaches a set value and forming combustion and explosion mixed gas, and then closing the first stop valve and the second stop valve;

step three: opening a third stop valve, injecting the mixed combustion and explosion mixed gas into the combustion and explosion mixed gas storage tank until the combustion and explosion mixed gas is filled in the combustion and explosion mixed gas storage tank, and then closing the third stop valve;

step four: opening a fourth stop valve, a fifth stop valve and a combustion and explosion mixed gas control valve group in the intelligent ignition control cabinet, simultaneously starting a booster pump, injecting combustion and explosion mixed gas in a combustion and explosion mixed gas storage tank into a combustion and explosion mixed gas jet hole of a combustion and explosion controller through a combustion and explosion mixed gas input pipe, jacking a jet hole sealing plate under the action of pressure difference to enable a sealing plate reset spring to be in an extension state, continuously filling high-pressure combustion and explosion mixed gas into a drill hole, and when the pressure difference between the combustion and explosion mixed gas jet hole and the drill hole is reduced to be insufficient to overcome the spring force of the sealing plate reset spring, enabling the jet hole sealing plate to be closed again under the action of the spring force of the sealing plate reset spring, closing the booster pump, and simultaneously closing the fourth stop valve, the fifth stop valve and the combustion and explosion mixed gas control valve group in the intelligent ignition control cabinet;

step five: controlling an ignition electrode to generate electric sparks through an intelligent ignition control cabinet, detonating combustion and explosion mixed gas in a drill hole by using the electric sparks, enabling a coal seam around the drill hole to generate cracks under the action of explosion impact, and enabling adjacent drill holes to be communicated through the cracks;

step six: removing the drill holes from the components in the holes, then alternately inserting gas extraction pipes and carbon dioxide gas injection pipes into the plurality of drill holes, installing gas extraction plugs at the hole openings of all the drill holes, enabling the gas extraction pipes and the carbon dioxide gas injection pipes to hermetically penetrate through the gas extraction plugs, sleeving inflatable hole sealing bags outside the gas extraction plugs, and filling air into the inflatable hole sealing bags to complete hole sealing of the drill holes;

step seven: the method comprises the steps of connecting a gas extraction pipe into negative-pressure gas extraction equipment in a mine, connecting a carbon dioxide gas injection pipe into carbon dioxide gas supply equipment in the mine, starting the negative-pressure gas extraction equipment and the carbon dioxide gas supply equipment, injecting carbon dioxide gas into corresponding drill holes through the carbon dioxide gas injection pipe, enabling the carbon dioxide gas to enter peripheral cracks from the drill holes to be used for displacing gas in a coal seam, enabling the displaced gas to enter the drill holes for gas extraction through the cracks, and finally discharging the gas through the gas extraction pipe to achieve gas extraction.

The invention has the beneficial effects that:

according to the low-permeability and difficult-desorption coal seam blasting and gas injection combined enhanced gas extraction device and method, after drilling is completed, drilling equipment does not need to be removed, blasting permeability increase can be quickly started, and after permeability increase of coal rock is completed, gas extraction is completed in a carbon dioxide displacement complete mode. The method can effectively increase the crack development degree of the low-permeability and difficult-desorption coal seam, further enhance the gas extraction effect and effectively reduce the gas outburst and gas explosion risks.

Drawings

FIG. 1 is a schematic structural diagram of a low-permeability and difficult-desorption coal seam blasting and gas injection combined enhanced gas extraction device;

FIG. 2 is a schematic structural diagram of the detonation controller of the present invention;

FIG. 3 is a schematic diagram of gas extraction;

in the figure, 1-PDC drill bit, 2-drill rod, 3-helical blade, 4-blasting permeability-increasing plug, 5-drilling hole, 6-inflatable hole sealing bag, 7-blasting controller, 8-blasting mixed gas input pipe, 9-blasting ignition lead wire, 10-intelligent ignition control cabinet, 11-ignition electrode, 12-blasting mixed gas blowhole, 13-blowhole sealing plate, 14-sealing plate supporting guide rod, 15-sealing plate supporting guide hole, 16-sealing plate return spring, 17-spring positioning plate, 18-three-way pipe, 19-gas storage tank, 20-gas-air mixing tank, 21-blasting mixed gas storage tank, 22-booster pump, 23-first stop valve, 24-second stop valve, 25-third stop valve, 26-fourth stop valve, 27-fifth stop valve, 28-one-way valve, 29-coal seam, 30-gas extraction pipe, 31-carbon dioxide gas injection pipe, 32-gas extraction plug.

Detailed Description

The invention is described in further detail below with reference to the figures and the specific embodiments.

As shown in fig. 1 and 2, the low permeability and difficult desorption coal seam blasting and gas injection combined enhanced gas extraction device comprises an in-hole component and an out-hole component; the in-hole assembly comprises a PDC drill bit 1, a drill rod 2, a helical blade 3 and a blasting permeability-increasing plug 4; the PDC drill bit 1 is installed at the bottom end of the drill rod 2, and the blasting permeability-increasing plug 4 is installed at the top end of the drill rod 2 and is positioned at the orifice of the drill hole 5; an inflatable hole sealing bag 6 is sleeved outside the blasting permeability-increasing plug 4; the helical blade 3 is arranged on the surface of the rod body of the drill rod 2; a plurality of blasting controllers 7 are arranged on the surface of the rod body of the drill rod 2, and each blasting controller 7 is externally connected with a blasting mixed gas input pipe 8 and a blasting ignition lead 9; the assembly outside the hole comprises a burning and blasting mixed gas supply mechanism and an intelligent ignition control cabinet 10, and a burning and blasting mixed gas control valve group is also arranged in the intelligent ignition control cabinet 10; the blasting ignition lead 9 hermetically penetrates through the blasting anti-reflection plug 4 and is connected with an intelligent ignition control cabinet 10; and the blasting mixed gas input pipe 8 penetrates through the blasting permeability-increasing plug 4 in a sealing manner to be connected with the gas outlet end of a blasting mixed gas control valve group in the intelligent ignition control cabinet 10, and the gas inlet end of the blasting mixed gas control valve group is connected with a blasting mixed gas supply mechanism.

The explosion controllers 7 are positioned between the two adjacent spiral blades 3, a 90-degree phase angle is formed between the two adjacent explosion controllers 7, and all the explosion controllers 7 are distributed on the rod body of the drill rod 2 in a spiral state space.

The explosion controller 7 comprises an ignition electrode 11, an explosion mixed gas jet hole 12, a jet hole sealing plate 13, a sealing plate supporting guide rod 14, a sealing plate supporting guide hole 15, a sealing plate return spring 16, a spring positioning plate 17 and a three-way pipe 18; an ignition electrode mounting hole is formed in the rod body of the drill rod 2, and the ignition electrode 11 is located in the ignition electrode mounting hole; the number of the blasting mixed gas injection holes 12 is two and the blasting mixed gas injection holes are symmetrically distributed on two sides of the ignition electrode 11; the sealing plate supporting guide hole 15 is positioned at the outer side of the blasting mixed gas jet hole 12, the jet hole sealing plate 13 is positioned at the outlet side of the blasting mixed gas jet hole 12, the sealing plate supporting guide rod 14 is positioned in the sealing plate supporting guide hole 15, and one end of the sealing plate supporting guide rod 14 is fixedly connected with the jet hole sealing plate 13; the sealing plate reset spring 16 is positioned in the sealing plate support guide hole 15, the other end of the sealing plate support guide rod 14 is fixedly connected with one end of the sealing plate reset spring 16, and the other end of the sealing plate reset spring 16 is fixedly connected with the rod body of the drill rod 2 through the spring positioning plate 17; the inlet sides of the two blasting mixed gas injection holes 12 are communicated with a blasting mixed gas input pipe 8 through a three-way pipe 18; the ignition electrode 11 is connected with the blasting ignition lead 9.

The blasting mixed gas supply mechanism comprises a gas storage tank 19, a gas-air mixing tank 20, a blasting mixed gas storage tank 21 and a booster pump 22; an air outlet of the gas storage tank 19 is communicated with a gas inlet of the gas-air mixing tank 20, and a first stop valve 23 is arranged on a pipeline between the gas storage tank and the gas inlet; an air inlet of the gas-air mixing tank 20 is communicated with a dry air supply source, and a second stop valve 24 is arranged on a pipeline between the gas inlet and the dry air supply source; a mixed gas outlet of the gas-air mixing tank 20 is communicated with an air inlet of the combustion and explosion mixed gas storage tank 21, and a third stop valve 25 is arranged on a pipeline between the gas outlet and the air inlet; an air outlet of the blasting mixed gas storage tank 21 is communicated with an air inlet of the booster pump 22, and a fourth stop valve 26 is arranged on a pipeline between the blasting mixed gas storage tank and the booster pump; the gas outlet of the booster pump 22 is communicated with the gas inlet end of the combustion and explosion mixed control valve group in the intelligent ignition control cabinet 10, a fifth stop valve 27 and a check valve 28 are sequentially arranged on a pipeline between the gas outlet of the booster pump and the gas inlet end of the combustion and explosion mixed control valve group in the intelligent ignition control cabinet 10, and the gas outlet of the check valve 28 is communicated with the gas inlet end of the combustion and explosion mixed control valve group in the intelligent ignition control cabinet 10.

A low permeability and difficult desorption coal bed blasting and gas injection combined enhanced gas extraction method adopts the low permeability and difficult desorption coal bed blasting and gas injection combined enhanced gas extraction device and comprises the following steps:

the method comprises the following steps: selecting a gas extraction area of a coal seam 29, setting a drilling position in the selected area, completing drilling operation of a drill hole 5 by adopting a parallel drilling method and an in-hole assembly consisting of a PDC drill bit 1, a drill rod 2, a helical blade 3 and a blasting anti-reflection plug 4, after drilling is finished, keeping the in-hole assembly in the drill hole 5, and then completing hole sealing of the drill hole 5 by inflating an inflatable hole sealing bag 6;

step two: opening a first stop valve 23, injecting gas into the gas-air mixing tank 20 through the gas storage tank 19, simultaneously opening a second stop valve 24, injecting dry air into the gas-air mixing tank 20 through a dry air supply source until the gas concentration of the gas-air mixing tank 20 reaches a set value and forming an explosion mixed gas, and then closing the first stop valve 23 and the second stop valve 24; in the embodiment, the gas concentration in the combustion and explosion mixed gas is set to be 9-10 percent;

step three: opening the third stop valve 25, injecting the mixed blasting mixed gas into the blasting mixed gas storage tank 21 until the blasting mixed gas is filled in the blasting mixed gas storage tank 21, and then closing the third stop valve 25;

step four: the fourth stop valve 26, the fifth stop valve 27 and the blasting mixture control valve group in the intelligent ignition control cabinet 10 are opened, meanwhile, the booster pump 22 is started, the blasting mixed gas in the blasting mixed gas storage tank 21 is injected into the blasting mixed gas injection hole 12 of the blasting controller 7 through the blasting mixed gas input pipe 8, under the action of the pressure difference, the gas orifice sealing plate 13 is pushed open, so that the sealing plate return spring 16 is in an extension state, high-pressure combustion and explosion mixed gas is continuously filled into the drill hole 5, when the pressure difference between the blasting mixture gas injection hole 12 and the drilled hole 5 is reduced to be insufficient to overcome the spring force of the seal plate return spring 16, the gas orifice sealing plate 13 is closed again by the spring force of the sealing plate return spring 16, at which point the booster pump 22 is shut down, simultaneously closing the fourth stop valve 26, the fifth stop valve 27 and the combustion and explosion mixed gas control valve group in the intelligent ignition control cabinet 10; in this embodiment, the booster pump 22 controls the gas injection pressure of the blasting mixture gas to 10 MPa;

step five: the intelligent ignition control cabinet 10 controls the ignition electrode 11 to generate electric sparks, the electric sparks are used for detonating the combustion and explosion mixed gas in the drill hole 5, the coal seam 29 around the drill hole 5 generates cracks under the action of explosion impact, and the adjacent drill holes 5 are communicated through the cracks;

step six: removing the drill holes 5 from the components in the holes, then alternately inserting gas extraction pipes 30 and carbon dioxide gas injection pipes 31 into the drill holes 5, installing gas extraction plugs 32 at the hole openings of all the drill holes 5, enabling the gas extraction pipes 30 and the carbon dioxide gas injection pipes 31 to pass through the gas extraction plugs 32 in a sealing mode, sleeving inflatable hole sealing bags 6 outside the gas extraction plugs 32, and completing hole sealing of the drill holes 5 by inflating the inflatable hole sealing bags 6, as shown in fig. 3;

step seven: the method comprises the steps of connecting a gas extraction pipe 30 to negative-pressure gas extraction equipment in a mine, connecting a carbon dioxide gas injection pipe 31 to carbon dioxide gas supply equipment in the mine, starting the negative-pressure gas extraction equipment and the carbon dioxide gas supply equipment, injecting carbon dioxide gas into a corresponding drill hole 5 through the carbon dioxide gas injection pipe 31, enabling the carbon dioxide gas to enter peripheral cracks from the drill hole 5 to be used for displacing gas in a coal seam 29, enabling the displaced gas to enter the drill hole 5 for gas extraction through cracks, and finally discharging the gas through the gas extraction pipe 30 to achieve gas extraction.

The embodiments are not intended to limit the scope of the present invention, and all equivalent implementations or modifications without departing from the scope of the present invention are intended to be included in the scope of the present invention.