Multi-channel gas extraction pipe hole sealing and recovery device and method

Abstract

This invention discloses a sealing and recovery device and method for a multi-channel gas extraction pipe, belonging to the field of gas extraction device and recovery technology. The device includes a bladder, a multi-channel gas extraction pipe, a protective pipe, and a recovery device. The multi-channel gas extraction pipe has a cross-shaped partition inside, forming four channels: two gas extraction channels, a grouting material channel, and a liquid injection channel. The bladder has a cylindrical structure, with two bladders respectively fitted onto the outer walls of the multi-channel gas extraction pipe at both ends. The bladder contains several sets of buoyancy plates, each set connected in series by two traction ropes, with both ends of the traction ropes connected to the inner wall of the bladder. This invention integrates the grouting material pipeline, the gas extraction pipeline, and the liquid injection channel into one unit, achieving multiple uses with a single pipe and thus saving economic costs. After the grouting sealing material solidifies, the multi-channel gas extraction pipe and the bladder can be recovered, realizing the recovery and multiple uses of the gas extraction pipe and the bladder within the solidified sealing material.

Description

Technical Field

[0001] This invention relates to a multi-channel gas extraction pipe sealing and recovery device and method, belonging to the field of gas extraction device and recovery technology. Background Technology

[0002] As coal resources in low-gas areas of my country are gradually depleted, coal mining will extend to high-gas areas of coalfields. Coal seam gas is currently a major hidden danger affecting coal mine safety. During the coal seam mining process, gas accumulation and concentration exceeding limits, coal and gas outbursts are likely to occur. In order to prevent gas accidents from restricting safe production during mining, coal seam gas extraction can effectively reduce the gas content in the coal seam, thereby reducing gas accidents.

[0003] The key to the effectiveness of coal seam gas drainage lies in the quality of borehole sealing and the supporting equipment. Currently, the commonly used sealing methods for gas drainage boreholes include polyurethane material sealing and cement-based material sealing. Some researchers have also developed retarded or non-setting materials for sealing. Polyurethane materials soften easily when exposed to water, have poor permeability, and release a large amount of heat when dissolved in water, which can easily cause safety accidents. Due to economic constraints and limitations in the development of non-setting or retarded materials, cement-based material grouting sealing is currently the most widely used method for sealing gas drainage boreholes.

[0004] Due to the generally low permeability of coal seams in my country, extensive and intensive drilling for coal seam gas extraction is necessary. The annual drilling length for underground gas extraction boreholes in my country is approximately 150 million meters, and the cost of existing sealing pipes is as high as several billion yuan. However, existing sealing devices (including grouting pipes, gas extraction pipes, and gas bags) face the following challenges: the gas extraction pipes are difficult to recover, and the recovery efficiency is low; the need to bundle and assemble grouting pipes, gas extraction pipes, and gas bags causes inconvenience in underground operations; and after recovery, damaged extraction pipes and other items are difficult to reuse.

[0005] Existing research directions involve recyclable dynamic sealing devices for gas boreholes. Chinese patent CN112412388A (for non-coagulating materials) discloses a reusable integrated two-plug-one-injection sealing packer for gas boreholes, and Chinese patent CN212130542U (for non-coagulating constant pressure slurry) discloses a non-coagulating constant pressure slurry bag sealing system for gas extraction boreholes. However, due to the fact that the dynamic sealing material is a fluid liquid, it cannot provide good support for the inner wall of the coal seam in the borehole sealing section. At the same time, the inner wall of the coal seam is constantly immersed in the sealing material, which may cause the sealing material to mix with coal and rock debris. During the process of discharging the sealing material, the pipeline may be blocked, resulting in the problem that the sealing material cannot be discharged from the sealing section.

[0006] Therefore, there is an urgent need for a recyclable gas extraction borehole sealing device that can recycle the gas extraction device regardless of whether the sealing material is non-solid or solid. At the same time, it can minimize the damage to the gas extraction device during the recycling process and significantly reduce the cost of borehole sealing. Summary of the Invention

[0007] To address the aforementioned issues of sealing and recovery during gas extraction, this invention provides a sealing and recovery device and method for a multi-channel gas extraction pipe. It relates to a specially structured bladder and a multi-channel gas extraction pipe, which integrates a gas extraction pipe, a grouting pipe, and a liquid injection pipe into a single unit. An external protective pipe is designed around the multi-channel gas extraction pipe to form a recyclable device.

[0008] The recycling device provided by this invention is applicable to the field of mine gas drainage borehole sealing. It can recycle and reuse gas drainage pipes and bags for both non-solid and solidified sealing materials. Through a single multi-channel gas drainage pipe, it completes coal seam gas extraction, grouting and sealing of the plugging section, and hydraulic grouting of the bag body. Simultaneously, it can achieve non-destructive recycling of the gas drainage pipe and bag. This invention also designs a novel bag structure: a cylindrical bag is fitted onto the outer wall of the multi-channel gas drainage pipe, with multiple protective films on the inward-facing side of the two bags. Multiple sets of buoyancy plates are designed inside the bag, allowing for expansion and contraction of the bag through liquid injection and extraction.

[0009] This invention provides a sealing and recovery device for a multi-channel gas extraction pipe, comprising: a bag, a multi-channel gas extraction pipe, a protective pipe, and a recovery device;

[0010] The multi-channel gas extraction pipe has a cross-shaped partition inside, forming four channels, which are not connected to each other. They are two gas extraction channels, a grouting material channel, and a liquid injection channel.

[0011] The bag is a cylindrical structure with two bags respectively fitted onto the outer walls of the multi-channel gas extraction pipe. Inside the bag are several sets of buoyancy plates, each set of buoyancy plates is connected in series by two traction ropes, and the two ends of the traction ropes are connected to the inner wall of the bag.

[0012] The multi-channel gas extraction pipe has a groove at each end, and the groove is arranged around the outer wall of the pipe. Two gas bags are respectively placed in the groove. A protective pipe is provided on the outside of the multi-channel gas extraction pipe, and the protective pipe is located between the two gas bags. The space enclosed by the protective pipe, the inner side of the two gas bags, and the coal wall forms a grouting and sealing area.

[0013] Specifically, taking its expanded state as an example, the inner ends of the two opposing bags are provided with polyvinyl chloride rings, which are integral with the bags, while the rest of the bags are flexible structures. When the bags are filled with liquid, the buoyancy plates are suspended inside the bags under the buoyancy of the liquid, supporting the bags into a cylindrical structure. When the liquid inside the bags is extracted, the buoyancy plates connected in series pull the bags back into the groove of the multi-channel gas extraction pipe through the reaction force on the liquid. Furthermore, the inner wall of the bags is fixed to the groove of the multi-channel gas extraction pipe by vulcanization bonding, so that the bags and the multi-channel gas extraction pipe form a non-removable integrated body, saving the connection process. Furthermore, the multi-channel gas extraction pipe has a groove on the outside for storing bags, and a connecting pipe is provided inside the groove. One end of the connecting pipe communicates with the injection channel, and the other end is connected to the through hole inside the bag.

[0014] Specifically, the inner surfaces of the two opposing pouches are provided with multiple protective films, which do not cover the polyvinyl chloride ring. Preferably, the multiple protective films have high tensile strength, high tear strength, and high abrasion resistance, and the protective films are stable and not easily decomposed. Therefore, thermoplastic polyurethane material is selected as the protective film.

[0015] Preferably, the protective tube is designed as a ring-shaped tubular structure, with the inner diameter of the protective tube slightly larger than the outer diameter of the multi-channel gas extraction tube, and the end is connected to a 2cm wide annular connecting plate. The annular connecting plate is bonded to the polyvinyl chloride ring of the bag by a peelable adhesive. In particular, the protective tube should have characteristics such as high compressive strength. Therefore, fiber-reinforced composite material tube is selected as the protective tube.

[0016] Preferably, the multi-channel gas extraction pipe has four channels inside. For ease of description, the four channels inside the multi-channel gas extraction pipe are designated as channels A, B, C, and D in a clockwise direction. Among them, channels A and C are two gas extraction channels, channel B is a grouting material channel, and channel D is a liquid injection channel used to inject liquid to inflate the bag.

[0017] Specifically, the A and C channels of the multi-channel gas extraction pipe are 0.5 meters longer than the B and D channels in the horizontal direction.

[0018] Preferably, a one-way valve is provided on the grouting material channel, and the one-way valve is connected to the grouting sealing area, that is, it is used to fill the gap between the protective pipe and the borehole;

[0019] Preferably, the gas extraction channel is connected to the gas extraction pump, and a gas flow meter is installed at the inlet of the gas extraction channel to monitor the change in gas concentration during the extraction process.

[0020] Preferably, the fan-shaped end faces of the injection channel D and the grouting material channel B of the multi-channel gas extraction pipe are both closed structures.

[0021] Preferably, an injection port is provided at the right end of the injection channel D, which is tightly connected to the injection pipe by a self-tightening nut I, and the injection pipe is connected to the injection pump; preferably, a flow meter I and a pressure gauge I are provided on the injection pipe to monitor the changes in pressure and flow rate inside the bladder during the injection process;

[0022] Preferably, a grouting port is provided at the right end of the grouting material channel B, which is tightly connected to the grouting pipe by a self-tightening nut II, and the grouting pipe is connected to the grouting material pump; a pressure gauge II and a flow meter II are provided at the inlet end of the grouting material channel to monitor the pressure and flow rate changes of the grout during the grouting process.

[0023] Preferably, a guide pipe is connected to the other end of the grouting pipe, and the guide pipe is connected to the cleaning pump; the grouting pipe and the grouting material channel B need to be cleaned.

[0024] Preferably, the recovery equipment includes a pulling device, a screw drive device, and two motors providing power. The pulling device consists of pulling clamps, and the screw drive device mainly consists of a helical gear platform. The helical gear platform includes two vertical gears and a gear base. A drive shaft is located in the middle of the gears, and the drive shaft is connected to the motors. The two gears mesh with the helical grooves on the multi-channel gas extraction pipe. Driven by the motors, the two gears rotate in opposite directions, pulling the multi-channel gas extraction pipe out of the borehole. The gear base supports the pulled-out multi-channel gas extraction pipe. Preferably, for ease of recovery, a protruding structure is provided on the outer right end of the multi-channel gas extraction pipe, which meshes with the pulling clamps of the recovery equipment. A helical groove structure is provided in the middle of the outer wall of the multi-channel gas extraction pipe, which meshes with the gears of the screw drive device of the recovery equipment.

[0025] Preferably, after gas extraction is completed, the pulling clamp is engaged with the protruding structure of the A and C channels of the multi-channel gas extraction pipe to activate the pulling device and pull the protective tube and the bag apart.

[0026] Preferably, after the protective tube and the bag are separated, the screw drive device is replaced, the multi-channel gas extraction tube is placed on the screw gear table, the gear position is adjusted, the screw groove structure on the multi-channel gas extraction tube is engaged with the gear, the screw drive device is started, and the screw rotation is converted into the horizontal movement of the multi-channel gas extraction tube, thereby recovering the multi-channel gas extraction tube and the bag.

[0027] This invention provides a method for sealing and recovering multi-channel gas extraction pipes, comprising the following steps:

[0028] S1: Lay the multi-channel gas extraction pipe with the bag flat, put the protective pipe in the middle of the multi-channel gas extraction pipe, and glue the annular connecting plate of the protective pipe to the polyvinyl chloride ring on the bag with peelable adhesive. After gluing, let it stand for no less than 30 minutes to ensure the initial bonding strength.

[0029] S2: Smoothly insert the assembled device from S1 into the designed depth of the coal seam borehole (90%-95% of the borehole depth). Seal the injection pipe to the injection channel (D channel) interface of the multi-channel gas extraction pipe using a self-tightening nut, and connect the other end of the injection pipe to the injection pump. Similarly, connect the grouting pipe to the grouting material channel (B channel) interface of the multi-channel gas extraction pipe, and connect the other end of the grouting pipe to the grouting material pump.

[0030] S3: Turn on the injection pump and the flow meter and pressure gauge on the injection pipe. Slowly inject clean water into the two grouting bags at an initial flow rate of 5 L / min-10 L / min. After the bags have made initial contact with the borehole wall, stabilize the injection pressure at 1.0 MPa-2.0 MPa and maintain it for 1-2 minutes to allow the bags to fully expand and tightly adhere to the borehole wall. A closed annular grouting sealing area is formed between the two expanded bags.

[0031] S4: Maintain stable internal pressure within the bladder in S3, and calculate the required grout volume for the sealing area (based on the designed sealing section length and borehole diameter). Start the grouting material pump and rapidly inject the grouting material into the sealing area at a flow rate of 30 L / min-50 L / min. The grouting pressure should be controlled between 1.5 MPa and 2.0 MPa until the grout fills the closed space formed by the bladder, protective pipe, and coal wall.

[0032] S5: After reaching the predetermined grouting volume, turn off the grouting material pump. Open the guide pipe valve and start the cleaning pump to inject clean water into the grouting pipe at a flow rate of 20L / min-30L / min. The flushing time should last for 3-5 minutes until the clean water is discharged to prevent the grout from solidifying in the pipe and to facilitate later recycling.

[0033] S6: Connect the gas extraction pump, gas flow meter and gas extraction channel. After checking that the device is airtight, start the gas extraction pump to extract gas.

[0034] S7: Once the concentration of gas to be extracted has decreased to the level required for safe production in the mine, i.e., when gas extraction is no longer necessary, the gas extraction device can be recovered using recovery equipment. Recovery of the gas extraction device, i.e., recovery of the multi-channel gas extraction pipe, includes the following steps:

[0035] (1) Turn off the gas extraction pump, remove the gas flow meter, switch the injection pump mode, and extract the liquid from the first bag, the second bag and the injection pipe. After the liquid in the bag is completely extracted, remove the pressure gauge, flow meter, guide pipe, injection pump and grouting pump.

[0036] (2) Engage and fix the biting clamp of the pulling device and the protruding structure on the right side of the A and C channels of the multi-channel gas extraction pipe. Then start the pulling device and pull the multi-channel gas extraction pipe out of the borehole with a steady pulling force (not exceeding 30 kN). At this time, the PVC ring of the bag and the annular connecting plate of the protective pipe that are bonded to each other will gradually peel off under the action of the pulling force. The sealing section will be left with a cylinder formed by the protective film, the protective pipe and the solidified sealing material. After the multi-channel gas extraction pipe is pulled out to a length of 0.5m, stop pulling, close and unload the pulling device.

[0037] (3) Place the partially pulled-out multi-channel gas extraction pipe on the gear table of the screw drive device, mesh the screw groove on the extraction pipe with the gear (the extraction pipe is located between the two gears, and the tooth grooves on both sides of the extraction pipe mesh with the two gears respectively), then start the motor to drive the two gears of the screw drive device to rotate in opposite directions, and smoothly screw the multi-channel gas extraction pipe out of the borehole at a linear speed of 0.2 - 0.5 m / min to achieve the non-destructive recovery of the gas extraction pipe;

[0038] (4) After simple cleaning of the multi-channel gas extraction pipe and bag that are spun out, they can be used for subsequent gas extraction borehole plugging.

[0039] The beneficial effects of this invention are:

[0040] (1) This invention not only provides a practical gas extraction pipe sealing and recycling device, but also provides a matching recycling method, which avoids the waste caused by abandoned gas extraction pipes and reduces extraction costs.

[0041] (2) The multi-channel gas extraction sealing and recovery device combines the grouting pipe, gas extraction pipe and bag expansion material transportation pipe into one, which is covered with a multi-layer protective film on the outside, has a series of buoyancy plates inside, a multi-channel gas extraction pipe, and a protective pipe. This realizes multiple uses of one pipe, saves economic costs, and makes the sealing operation simpler.

[0042] (3) After the gas extraction is completed, the multi-channel gas extraction pipe and bag are recovered without damage, realizing the recovery and multiple uses of the gas extraction pipe and bag in the sealing solidification material. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the multi-channel gas extraction pipe and the gas bag during the grouting process;

[0044] Figure 2 A schematic diagram of the gas extraction pipe recovery process;

[0045] Figure 3 A schematic diagram of the three-dimensional structure of a multi-channel gas extraction pipe;

[0046] Figure 4 This is a schematic diagram of the cross-section of a multi-channel gas extraction pipe;

[0047] Figure 5 A schematic diagram of the three-dimensional structure of the sac in an inflated state;

[0048] Figure 6 This is a schematic diagram of the longitudinal section of the bladder in its inflated state.

[0049] Figure 7 This is a schematic diagram of the cross-section of the bladder in its inflated state.

[0050] Figure 8 A three-dimensional structural diagram of the protective tube;

[0051] Figure 9 This is a three-dimensional structural diagram of a screw drive device;

[0052] Figure 10 This is a schematic diagram of the recovery process of a multi-channel gas extraction pipe.

[0053] In the diagram: 1. Coal body; 2. Borehole; 3. Grouting and sealing section; 4. Bag; 5. Buoyancy plate; 6. Traction rope; 7. Multi-layer protective membrane; 8. Multi-channel gas extraction pipe; 9. Groove; 10. Connecting pipe; 11. Check valve; 12. Protective pipe; 13. Injection port; 14. Injection pipe; 15. Self-tightening nut I; 16. Pressure gauge I; 17. Flow meter I; 18. Injection pump; 19. Grouting port; 20. Grouting pipe; 21. Self-tightening nut II; 22. Pressure gauge II; 23. Flow meter II; 24. 25. Grouting material pump; 26. Guide pipe; 27. Cleaning pump; 28. Gas flow meter; 29. ​​Gas extraction pump; 30. Gas extraction channel; 31. Grouting material channel; 32. Liquid injection channel; 33. D-channel fan-shaped sealing surface; 34. B-channel fan-shaped sealing surface; 35. Spiral groove; 36. Protruding structure; 37. Polyvinyl chloride ring; 38. Annular connecting plate; 39. Pull-out clamping pliers; 40. Motor; 41. Gear; 42. Sealing area; 43. Constricted bladder; 44. Gear platform. Detailed Implementation

[0054] The present invention will be further illustrated by the following embodiments, but is not limited to the following embodiments. Example 1

[0055] like Figures 1-10 As shown, a multi-channel gas extraction pipe sealing and recovery device includes: a bag 4, a multi-channel gas extraction pipe 8, a protective pipe 12, and a recovery device;

[0056] The multi-channel gas extraction pipe 8 has a cross-shaped partition inside, forming four channels, which are not connected to each other. They are two gas extraction channels 29, a grouting material channel 30, and a liquid injection channel 31.

[0057] The bag 4 is a cylindrical structure, with two bags 4 respectively fitted onto both ends of the outer wall of the multi-channel gas extraction pipe 8. Inside the bag 4 are 6 sets of buoyancy plates 5 and 12 traction ropes 6 (see...). Figure 6 and Figure 7 Each set of buoyancy plates 5 contains five buoyancy plates, which are connected in series by two traction ropes 6. The buoyancy plates 5 are made of flexible polyethylene foam material. The two ends of the traction ropes 6 are connected to the inner wall of the bag 4. A through hole is provided in the center of the inner side of the bag 4.

[0058] The multi-channel gas extraction pipe 8 has a groove 9 at each end. The groove 9 is arranged in a circle on the outer wall of the pipe, and two bags 4 are respectively placed in the groove. A protective pipe 12 is provided on the outside of the multi-channel gas extraction pipe 8, and the protective pipe 12 is located between the two bags 4. The space enclosed by the protective pipe, the inner side of the two bags, and the coal wall forms a grouting and sealing area.

[0059] Specifically, taking its inflated state as an example, the inner ends of the two opposing bags 4 have a relatively rigid polyvinyl chloride ring 36 with a width of 2cm. This ring is integral with the bag 4, while the rest of the bag is made of a flexible material structure (Oxford cloth). When the bag 4 is filled with liquid, the buoyancy plate 5 is suspended inside the bag 4 under the action of liquid buoyancy, supporting the bag 4 into a cylindrical structure. When the bag 4 is drained of liquid, the buoyancy plates 5 connected in series pull the bag 4 back into the groove of the multi-channel gas extraction pipe 8 through the reaction force of the liquid. Furthermore, the inner wall of the bag 4 is fixed to the groove 9 by vulcanization bonding, so that the bag and the multi-channel gas extraction pipe form a non-removable integrated body, saving the connection process. Furthermore, the multi-channel gas extraction pipe 8 has a groove 9 on the outside for storing the bag, and a connecting pipe 10 is provided inside the groove. One end of the connecting pipe is connected to the liquid injection channel, and the other end is connected to the through hole inside the bag.

[0060] Specifically, the inner surfaces of the two pouches 4 facing each other are provided with multiple protective films 7, which do not cover the polyvinyl chloride ring 36. Preferably, the multiple protective films 7 have high tensile strength, high tear strength, and high abrasion resistance, and the protective film is stable and not easily decomposed. Therefore, thermoplastic polyurethane material is selected as the protective film.

[0061] Preferably, the protective tube 12 is designed as an annular tubular structure, with the inner diameter of the protective tube 12 being slightly larger than the outer diameter of the multi-channel gas extraction tube 8, and the end is connected to an annular connecting plate 37 with a width of 2cm. The annular connecting plate 37 is connected to the polyvinyl chloride ring 36 of the bag. In particular, the protective tube 12 should have characteristics such as high compressive strength. Therefore, fiber reinforced composite material tube is selected as the protective tube.

[0062] Preferably, the multi-channel gas extraction pipe 8 has four channels inside. For ease of description, the four channels inside the multi-channel gas extraction pipe are designated as channels A, B, C, and D in a clockwise direction. Among them, channels A and C are two gas extraction channels 29, channel B is a grouting material channel 30, and channel D is a liquid injection channel 31, which is used to inject liquid to inflate the bag.

[0063] Specifically, in the multi-channel gas extraction pipe, channels A and C have a horizontal length of 0.5 meters compared to the other two channels; this refers to... Figure 1 It extends 0.5 meters in the horizontal direction, and the extension section consists of two intersecting fan-shaped channels.

[0064] Preferably, a one-way valve 11 is provided on the grouting material channel 30. The one-way valve 11 is connected to the grouting sealing area, that is, it is used to fill the gap between the protective pipe and the borehole.

[0065] Preferably, the gas extraction channel is connected to the gas extraction pump, and a gas flow meter is installed at the inlet of the gas extraction channel to monitor the change in gas concentration during the extraction process.

[0066] Preferably, the fan-shaped end faces of the injection channel D and the grouting material channel B of the multi-channel gas extraction pipe are both closed structures.

[0067] Preferably, an injection port 13 is provided at the right end of the injection channel D, which is tightly connected to the injection pipe 14 by a self-tightening nut I 15, and the injection pipe 14 is connected to the injection pump 18; preferably, a flow meter I 17 and a pressure gauge I 16 are provided on the injection pipe 14 to monitor the changes in pressure and flow rate inside the bladder during the injection process.

[0068] Preferably, a grouting port 19 is provided at the right end of the grouting material channel B, which is tightly connected to the grouting pipe 20 through a self-tightening nut II 21. The grouting pipe 20 is connected to the grouting material pump 24. A pressure gauge II 22 and a flow meter II 23 are provided at the inlet end of the grouting material channel to monitor the pressure and flow rate changes of the grout during the grouting process. The grouting material channel B is connected to the sealing area 41 through a one-way valve 11.

[0069] Preferably, a guide pipe 25 is connected to the other end of the grouting pipe 20, and the guide pipe 25 is connected to the cleaning pump 26; the grouting pipe and the grouting material channel B need to be cleaned.

[0070] Preferably, the recovery equipment includes a pulling device, a screw drive device, and a motor 39 for providing power. The pulling device mainly consists of a pulling clamp 38, and the screw drive device mainly consists of a helical gear platform 43. The helical gear platform 43 includes two vertical gears 40 and a gear platform 43. A drive shaft is provided in the middle of the gears 40, and the drive shaft is connected to the motor. The two gears 40 mesh with the helical grooves 34 on the multi-channel gas extraction pipe. Driven by the motor 39, the two gears 40 rotate in opposite directions, pulling the multi-channel gas extraction pipe out of the borehole. The gear platform 43 is used to support the pulled-out multi-channel gas extraction pipe.

[0071] Preferably, for ease of recovery, a protruding structure 35 is provided on the outer side of the right end of the A and C channels of the multi-channel gas extraction pipe, which engages with the pull-out clamp 38 of the recovery equipment. A spiral groove structure is provided on the outer side of the A and C channels, which engages with the gear of the spiral transmission device of the recovery equipment.

[0072] Preferably, after the gas extraction is completed, the pulling clamp 38 is engaged with the protruding structure 35 of the multi-channel gas extraction pipe A and C to activate the pulling device and pull the protective pipe 12 and the bag 4 apart.

[0073] Preferably, after the protective tube and the bag are separated, the screw drive device is replaced, the multi-channel gas extraction tube is placed on the screw gear table, the gear position is adjusted, the screw groove on the multi-channel gas extraction tube is engaged with the gear, the screw drive device is started, and the screw rotation is converted into the horizontal movement of the multi-channel gas extraction tube, thereby recovering the multi-channel gas extraction tube and the bag.

[0074] This invention provides a method for sealing and recovering multi-channel gas extraction pipes, comprising the following steps:

[0075] S1: Lay the multi-channel gas extraction pipe with the bag flat, put the protective pipe in the middle of the multi-channel gas extraction pipe, and glue the annular connecting plate of the protective pipe to the polyvinyl chloride ring on the bag with peelable adhesive. After gluing, let it stand for no less than 30 minutes to ensure the initial bonding strength.

[0076] S2: Smoothly insert the assembled device from S1 into the designed depth of the coal seam borehole (90%-95% of the borehole depth). Seal the injection pipe to the injection channel (D channel) interface of the multi-channel gas extraction pipe using a self-tightening nut, and connect the other end of the injection pipe to the injection pump. Similarly, connect the grouting pipe to the grouting material channel (B channel) interface of the multi-channel gas extraction pipe, and connect the other end of the grouting pipe to the grouting material pump.

[0077] S3: Turn on the injection pump and the flow meter and pressure gauge on the pipeline. Slowly inject clean water into the two grouting bags at an initial flow rate of 5 L / min-10 L / min. After the bags have made initial contact with the borehole wall, stabilize the injection pressure at 1.0 MPa ± 0.1 MPa and maintain it for 1-2 minutes to allow the bags to fully expand and tightly adhere to the borehole wall. A closed annular grouting sealing area is formed between the two expanded bags.

[0078] S4: Maintain stable internal pressure within the bladder in S3, and calculate the required grout volume for the sealing area (calculated based on the designed sealing section length and borehole diameter; for example, with a 120 mm diameter borehole and a sealing length of 12 m, the required grout volume should be no less than 135 L). Start the grouting material pump and rapidly inject the grouting material into the sealing area at a flow rate of 30 L / min. The grouting pressure should be controlled at 2 MPa until the grout fills the closed space enclosed by the bladder, protective pipe, and coal wall.

[0079] S5: After reaching the predetermined grouting volume, turn off the grouting material pump. Open the guide pipe valve, start the cleaning pump, and inject clean water into the grouting pipe at a flow rate of 20 L / min. The flushing time is 3 minutes until the clean water is discharged to prevent the grout from solidifying in the pipe and to facilitate later recycling.

[0080] S6: Connect the gas extraction pump, gas flow meter and gas extraction channel. After checking that the device is airtight, start the gas extraction pump to extract gas.

[0081] S7: Once the concentration of gas to be extracted has decreased to the level required for safe production in the mine, i.e., when gas extraction is no longer necessary, the gas extraction device can be recovered using recovery equipment. Recovery of the gas extraction device, i.e., recovery of the multi-channel gas extraction pipe, includes the following steps:

[0082] (1) Turn off the gas extraction pump, remove the gas flow meter, switch the injection pump mode, and extract the liquid from the first bag, the second bag and the injection pipe. After the liquid in the bag is completely extracted, remove the pressure gauge, flow meter, guide pipe, injection pump and grouting pump.

[0083] (2) Engage and fix the biting clamp of the pulling device and the protruding structure on the right side of the A and C channels of the multi-channel gas extraction pipe. Then start the pulling device and pull the extraction pipe out of the borehole with a steady pulling force (not exceeding 30 kN). At this time, the PVC ring of the bag and the annular connecting plate of the protective pipe that are bonded to each other will gradually peel off under the action of the pulling force. The sealing section will be left with a cylinder formed by the protective film, the protective pipe and the solidified sealing material. After the multi-channel gas extraction pipe is pulled out to a length of 0.5m, stop pulling, close and unload the pulling device.

[0084] (3) Place the partially pulled-out multi-channel gas extraction pipe on the gear platform of the screw drive device, mesh the helical groove on the extraction pipe with the gear (the extraction pipe is located between the two gears, and the tooth grooves on both sides of the extraction pipe mesh with the two gears respectively), then start the motor to drive the two gears of the screw drive device to rotate in opposite directions, so that the multi-channel gas extraction pipe is smoothly screwed out of the borehole at a linear speed of 0.2 m / min, realizing the non-destructive recovery of the gas extraction pipe; Figure 10 As shown (top view schematic diagram);

[0085] (4) After simple cleaning of the multi-channel gas extraction pipe and bag that are spun out, they can be used for subsequent gas extraction borehole plugging.

[0086] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0087] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multi-channel gas extraction pipe hole sealing and recovery device, characterized in that: The system includes gas extraction bags, a multi-channel gas extraction pipe, a protective pipe, and recovery equipment. The multi-channel gas extraction pipe has a cross-shaped partition inside, forming four channels that are not interconnected: two gas extraction channels, a grouting material channel, and a liquid injection channel. The gas extraction bags are cylindrical structures, with two bags fitted onto the outer walls of the multi-channel gas extraction pipe at both ends. Inside each bag are several sets of buoyancy plates, each set connected in series by two traction ropes. The ends of the traction ropes are connected to the inner wall of the bag, and a through hole is located at the center of the inner side of the bag. A protective pipe is located outside the multi-channel gas extraction pipe, between the two bags. The space enclosed by the protective pipe, the inner sides of the two bags, and the coal wall forms a grouting and sealing area. The recovery equipment includes a pulling device, a screw drive device, and two motors providing power. Two opposing inner sides of the two gas bags are provided with polyvinyl chloride (PVC) rings, which are integral with the gas bags. The rest of the gas bags are flexible structures. When the gas bags are filled with liquid, the buoyancy plates are suspended inside the gas bags under the buoyancy of the liquid, supporting the gas bags into a cylindrical structure. When the liquid inside the gas bags is extracted, the buoyancy plates connected in series pull the gas bags back into the groove of the multi-channel gas extraction pipe through the reaction force on the liquid. The opposing inner sides of the two gas bags are provided with multiple layers of protective film, which do not cover the PVC rings. The protective tube has a ring-shaped structure. The inner diameter of the protective tube is larger than the outer diameter of the multi-channel gas extraction tube, and the end is connected to a 2cm wide ring connecting plate. The ring connecting plate is bonded to the polyvinyl chloride ring of the bag with a peelable adhesive. The pulling device consists of a pulling clamp, and the spiral transmission device consists of a spiral gear platform. The spiral gear platform includes two vertical gears and a gear platform. A transmission shaft is provided in the middle of the gears. The transmission shaft is connected to a motor. The two gears mesh with the spiral grooves on the multi-channel gas extraction pipe. Driven by the motor, the two gears rotate in opposite directions, pulling the multi-channel gas extraction pipe out of the borehole. The gear table is used to support the pulled-out multi-channel gas extraction pipe.

2. The multi-channel gas extraction pipe sealing and recovery device according to claim 1, characterized in that: The multi-channel gas extraction pipe has a groove at each end, and the groove is located on the outer wall of the pipe. Two bags are respectively placed in the groove. A connecting pipe is installed inside the groove. One end of the connecting pipe is connected to the injection channel, and the other end is connected to the through hole inside the bag.

3. The multi-channel gas extraction pipe sealing and recovery device according to claim 1, characterized in that: The multilayer protective film is a thermoplastic polyurethane film.

4. The multi-channel gas extraction pipe sealing and recovery device according to claim 1, characterized in that: The protective tube is a fiber-reinforced composite material tube.

5. The multi-channel gas extraction pipe sealing and recovery device according to claim 1, characterized in that: The four channels inside the multi-channel gas extraction pipe are A, B, C, and D in a clockwise direction. Channels A and C are gas extraction channels, channel B is a grouting material channel, and channel D is a liquid injection channel used to inject liquid to inflate the bladder. Channels A and C of the multi-channel gas extraction pipe are 0.5 meters longer than channels B and D in the horizontal direction.

6. The multi-channel gas extraction pipe sealing and recovery device according to claim 5, characterized in that: A one-way valve is installed on the grouting material channel, which is connected to the grouting sealing area and is used to fill the gap between the protective pipe and the borehole. The gas extraction channel is connected to the gas extraction pump, and a gas flow meter is installed at the inlet of the gas extraction channel to monitor the change in gas concentration during the extraction process. The fan-shaped end faces of the injection channel D and the grouting material channel B of the multi-channel gas extraction pipe are both closed structures. An injection port is provided at the right end of the injection channel D, which is tightly connected to the injection pipe through a self-tightening nut I. The injection pipe is connected to the injection pump. A flow meter I and a pressure meter I are installed on the injection pipe to monitor the changes in pressure and flow rate inside the bladder during the injection process. A grouting port is provided at the right end of the grouting material channel B, which is tightly connected to the grouting pipe through a self-tightening nut II. The grouting pipe is connected to the grouting material pump. A pressure meter II and a flow meter II are installed at the inlet of the grouting material channel to monitor the changes in pressure and flow rate of the grout during the grouting process.

7. The multi-channel gas extraction pipe sealing and recovery device according to claim 1, characterized in that: The multi-channel gas extraction pipe has a raised structure on the outside, which engages with the pull-out clamp of the recovery equipment. The multi-channel gas extraction pipe has a spiral groove structure in the middle of its outer wall, which engages with the gear of the spiral drive device of the recovery equipment.

8. A method for sealing and recovering a multi-channel gas extraction pipe, comprising the multi-channel gas extraction pipe sealing and recovery device as described in any one of claims 1 to 7, characterized in that... Includes the following steps: S1: Lay the multi-channel gas extraction pipe with the bag flat, put the protective pipe on, and glue the annular connecting plate of the protective pipe to the polyvinyl chloride ring on the bag with peelable adhesive. S2: Send the assembled equipment in S1 into the coal seam borehole, and connect the injection pipe and injection channel D and injection pump, and connect the grouting pipe and grouting material channel B and grouting material pump; S3: Turn on the injection pump, flow meter and pressure gauge to slowly inject liquid into the bladder, gradually causing the bladder to expand and stick to the borehole wall. The expansion of the first bladder and the second bladder form a grouting and sealing area. S4: Maintain the injection pump pressure in S3 and calculate the amount of grout required to seal the grouting area. Then start the grouting material pump, turn on the pressure gauge and flow meter, and quickly inject the grouting sealing material into the grouting sealing area so that the grout comes into contact with the borehole wall and the outer wall of the bladder, and gradually fills the closed grouting sealing area formed between the first bladder, the second bladder, the protective pipe and the coal body. S5: Maintain the grouting speed in S4. After the predetermined grouting volume is reached, turn off the grouting material pump, open the guide pipe valve, start the cleaning pump, and inject clean water into the grouting pipe to clean it, thereby facilitating its later recycling. S6: Connect the gas extraction pump, gas flow meter and gas extraction channel. After checking that the device is airtight, start the gas extraction pump to extract gas. S7: Once the concentration of gas to be extracted has decreased to the level required for safe production in the mine, i.e., when gas extraction is no longer necessary, the gas extraction device can be recovered using recovery equipment; the recovery process includes the following steps: (1) Turn off the gas extraction pump, remove the gas flow meter, switch the injection pump mode, and extract the liquid from the first bag, the second bag and the injection pipe. After the liquid in the bag is completely extracted, remove the pressure gauge, flow meter, guide pipe, injection pump and grouting pump. (2) Engage and fix the biting clamp of the pulling device and the protruding structure on the right side of the A and C channels of the multi-channel gas extraction pipe. Then start the pulling device to pull the multi-channel gas extraction pipe toward the borehole. At this time, the PVC ring of the bag and the annular connecting plate of the protective pipe that are bonded to each other will gradually peel off under the action of the pulling force. The sealing section will be left with a cylinder formed by the protective film, the protective pipe and the solidified sealing material. After the multi-channel gas extraction pipe is pulled out to a length of 0.5m, stop pulling, close and unload the pulling device. (3) Place the multi-channel gas extraction pipe on the helical gear table of the helical transmission device, mesh the helical groove on the extraction pipe with the gear, the extraction pipe is located between the two gears, the tooth grooves on both sides of the extraction pipe mesh with the two gears respectively, and then start the helical transmission device to gradually rotate the multi-channel gas extraction pipe out to realize the recovery of the multi-channel gas extraction pipe. (4) Clean the multi-channel gas extraction pipe and bag that have been turned out, and use them for subsequent gas extraction borehole sealing.

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