Flexible pressure-maintaining intelligent sealing method for underground gas drainage boreholes in coal mines

Abstract

A flexible pressure-maintaining intelligent sealing method for underground gas drainage boreholes in coal mines includes the following steps: (1) arranging a slurry preparation system and slurry delivery pipeline; (2) preparing sealing slurry using a surface slurry preparation and storage system; (3) performing grouting and sealing operations into a reusable cylindrical rubber bladder sealing device; (4) connecting the gas drainage pipeline to perform gas drainage operations on the gas drainage borehole; (5) during the gas drainage operation, dynamically maintaining pressure on the reusable cylindrical rubber bladder sealing device and monitoring the sealing section in real time, triggering an alarm and taking action when the sealing section loses pressure. This invention prepares slurry on the surface and directly delivers it to a reusable cylindrical rubber bladder sealing device in each borehole in the underground roadway. It utilizes a control system to achieve highly intelligent grouting and sealing, ensuring precise and free control of sealing pressure and automatic pressure maintenance throughout the borehole sealing process. It has advantages such as small space occupation, simple operation, high degree of automation, low labor intensity for workers, and cost savings.

Description

Technical Field

[0001] This invention belongs to the field of coal mine gas extraction technology, specifically relating to a flexible pressure-maintaining intelligent sealing method for underground coal mine gas extraction boreholes. Background Technology

[0002] Traditional gas extraction and sealing processes typically involve drilling a borehole, inserting a sealing device, and then mixing sealing material and water in a mixing tank to form a slurry. This slurry is then injected into the sealing device using a grouting pump. After the slurry solidifies, the extraction pipe is connected to the extraction pipeline for gas extraction. However, because roadways are frequently deformed due to mining activities, the extraction borehole also deforms. A smaller borehole cross-sectional area improves sealing effectiveness, while a larger cross-sectional area causes gas leakage, affecting the gas extraction concentration. Therefore, it is crucial to monitor the pressure of existing sealing devices and replenish sealing slurry when the sealing pressure decreases to ensure effective sealing. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the present invention provides a flexible pressure-maintaining intelligent sealing method for underground gas extraction boreholes in coal mines that is easy to operate, easy to transport sealing slurry, and can ensure good sealing performance during the sealing process.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a flexible pressure-maintaining intelligent sealing method for underground gas drainage boreholes in coal mines, comprising the following steps:

[0005] (1) A surface slurry preparation and storage system and a main control PLC controller are arranged on the surface of the mine. A grouting pump station is arranged in the underground roadway. A cylindrical rubber bladder reusable sealing device is installed in several sets of gas extraction boreholes in the underground roadway. The outlet of the surface slurry preparation and storage system is connected to the inlet of the grouting pump station through the main slurry input pipe. The outlet of the grouting pump station is connected to the inlet of each set of cylindrical rubber bladder reusable sealing device through the underground slurry input main pipe.

[0006] (2) Preparation of sealing slurry using a ground-based slurry preparation and storage system;

[0007] (3) Grouting and sealing operations are performed inside the reusable sealing device for the cylindrical rubber bladder;

[0008] (4) Connect the gas extraction pipeline to the gas extraction borehole for gas extraction operation;

[0009] (5) During the gas extraction operation, the cylindrical rubber bladder reusable sealing device is dynamically pressure maintained, and the sealing section is monitored in real time. When the sealing section loses pressure, an alarm is triggered and measures are taken.

[0010] The ground pulping and storage system includes a silo, a mixing tank, and a belt conveyor. The feed end of the belt conveyor is located below the discharge port of the silo. The top of the mixing tank has a feed inlet. The discharge end of the belt conveyor is connected to the feed inlet via a transfer guide plate. The top of the mixing tank is equipped with a mixing motor. The main shaft of the mixing motor is driven to a stirrer located inside the mixing tank. A water supply pipe is connected to the upper side of the mixing tank. The water supply pipe is equipped with a water supply solenoid valve and a first flow sensor. A density sensor and a viscosity sensor are located on the lower part of the inner wall of the mixing tank. Liquid level sensors are located on both the upper and lower parts of the inner wall of the mixing tank.

[0011] Several gas drainage boreholes are drilled in the underground roadway. Boreholes evenly spaced along the length of the roadway form a group. Each group of boreholes contains a reusable cylindrical rubber bladder sealer. Each reusable cylindrical rubber bladder sealer includes a first cylindrical rubber bladder, a second cylindrical rubber bladder, an internal grouting pipe, and an inter-bladder grouting pipe. A drainage pipe is inserted into the central hole of the first and second cylindrical rubber bladders. The sac is located below the second cylindrical rubber sac. The grouting tube inside the sac passes through the first and second cylindrical rubber sacs from bottom to top. The upper end of the grouting tube inside the sac is sealed. The grouting tube inside the sac has a first grouting hole located in the first cylindrical rubber sac and a grouting hole located in the second cylindrical rubber sac. The upper end of the grouting tube between the sacs passes through the first cylindrical rubber sac from bottom to top and extends between the first and second cylindrical rubber sacs.

[0012] The lower end of the grouting pipe inside the sac is connected to the downhole slurry input main pipe through the first grouting hose, and the lower end of the grouting pipe between the sacs is connected to the downhole slurry input main pipe through the second grouting hose; the lower part of the grouting pipe inside the sac is provided with a first pressure sensor, a second flow sensor and a first solenoid valve in sequence from top to bottom; the lower part of the grouting pipe between the sacs is provided with a second pressure sensor, a third flow sensor and a second solenoid valve in sequence from top to bottom.

[0013] The downhole slurry input main pipe is equipped with a third solenoid valve, a fourth flow sensor, and a third pressure sensor in sequence along the slurry flow direction, and a fourth solenoid valve is installed on the slurry main input pipe.

[0014] The specific process of step (2) is as follows: According to the predetermined pulping amount, the main control PLC controller sends an instruction to the water supply pump connected to the water supply pipe inlet. At the same time, the belt conveyor, the mixing motor, and the screw feeder at the bottom of the silo are all started, and the water supply solenoid valve is opened to inject a certain amount of water into the mixing tank. According to the information of the first flow sensor, the predetermined water volume is reached and the water injection is stopped. The screw feeder quantitatively transports the solid material to the belt conveyor. The belt conveyor transports the solid material to the mixing tank. The mixing motor drives the agitator to start mixing, so that the solid material and water are fully mixed and stirred evenly until the predetermined ratio is reached to form a slurry with good fluidity. The slurry has good fluidity and a certain viscosity. The density sensor and viscosity sensor are used to measure the viscosity and density information of the slurry in real time and transmit it to the main control PLC controller. After the slurry is qualified, the mixing motor stops working.

[0015] The specific process of step (3) is as follows: According to the number of borehole groups, the cylindrical rubber reusable sealing devices with reserved corresponding interfaces are fixed side by side on one side of the roadway, and connected to the downhole slurry input main pipe through the first grouting hose and the second grouting hose. The cylindrical rubber reusable sealing device is inserted into the predetermined sealing depth of the borehole. The main control PLC controller instructs the fourth and third solenoid valves to open, the grouting pump station is started, and the slurry is transported through the main slurry input pipe and the downhole slurry input main pipe to the grouting pipe of the cylindrical rubber reusable sealing device at each sealing location. The main control PLC controller sends a pressure signal value through the third pressure sensor to control the third solenoid valve on the downhole slurry input main pipe to realize the pipeline opening and closing, so that the downhole slurry input main pipe can be connected to the pipeline. Maintain a constant grouting pressure. Then, the main PLC controller issues a sealing command. At this point, the first solenoid valve on the grouting pipe inside the bladder opens, and grout begins to be injected into the two first and second cylindrical rubber bladders through the first grouting hose and the grouting pipe inside the bladder. When the first pressure sensor detects that the set pressure value has been reached, the first solenoid valve closes, stopping the grouting. Next, the second solenoid valve on the grouting pipe between the bladders opens, and grout begins to be injected into the middle section between the first and second cylindrical rubber bladders through the second grouting hose and the grouting pipe between the bladders, until the second pressure sensor detects that the preset grouting pressure value has been reached. The main PLC controller then issues a command to close the second solenoid valve, stopping the grouting, and the sealing of one borehole is complete. The same procedure is used to complete the sealing operation of the other boreholes in the same group.

[0016] The specific process of dynamically maintaining pressure on the reusable cylindrical rubber bladder sealing device in step (5) is as follows: When the borehole deforms and the cross-section becomes larger, causing the pressure in the first cylindrical rubber bladder and / or the second cylindrical rubber bladder to decrease and be less than the predetermined constant pressure, the first pressure sensor transmits the pressure monitoring data to the main control PLC controller. The main control PLC controller instructs the first solenoid valve to open, and the grouting pipe inside the bladder begins to inject grout into the two first cylindrical rubber bladders and the second cylindrical rubber bladder. When the first pressure sensor detects that the set pressure value has been reached, the first solenoid valve closes and the grouting stops. Similarly, when the pressure drops in the middle section between the first and second cylindrical rubber bladders due to the continuous seepage of grout into the cracks around the borehole, the second solenoid valve connected to the grouting pipe between the bladders opens, and grout begins to be injected into the middle section between the first and second cylindrical rubber bladders through the grouting pipe between the bladders until the second pressure sensor detects that the preset grouting pressure value has been reached. The main control PLC controller then issues a command to close the second solenoid valve 48 to stop the grouting.

[0017] When the borehole deforms and its effective diameter decreases due to mining activities, the pressure on the first cylindrical rubber bladder, the second cylindrical rubber bladder, and the intermediate section increases. Because the first and second cylindrical rubber bladders are made of highly elastic rubber, they can withstand greater pressure, thus significantly improving the sealing effect. When the first and second pressure sensors detect a pressure exceeding the limit pressure that the first and second cylindrical rubber bladders can withstand, the main control PLC controller issues a command to open the first and second solenoid valves. The slurry inside the first and second cylindrical rubber bladders and the intermediate section can flow back into the downhole slurry input main pipe until it reaches equilibrium with the slurry pressure in the downhole slurry input main pipe, at which point the first and second solenoid valves close.

[0018] The specific process of real-time monitoring of the sealing section and alarm and handling when the sealing section loses pressure in step (5) is as follows:

[0019] A) Alarm and Handling Procedure for Pressure Loss in Cylindrical Rubber Bulbs: When a cylindrical rubber bulb ruptures and causes instantaneous grout leakage, resulting in a sharp drop in pressure monitored by the first pressure sensor, and grout injection fails to maintain pressure in the cylindrical rubber bulb, or pressure loss occurs shortly after the pressure rises, the system will stop injecting grout into the cylindrical rubber bulb to prevent a large amount of grout from flowing into the borehole or tunnel. An audible and visual alarm will be issued to indicate that the cylindrical rubber bulb in the borehole has ruptured due to pressure loss. At this time, the cylindrical rubber bulb in the borehole can be recovered first, and the ruptured cylindrical rubber bulb can be replaced before the borehole is sealed to ensure that the borehole can continue to pump normally.

[0020] B) Alarm and Handling of Pressure Loss in the Middle Section: When a large number of through-type fractures appear in the middle section of the borehole due to mining, resulting in severe slurry loss and a sharp drop in pressure monitored by the second pressure sensor, and the injection of slurry cannot maintain pressure in the middle section, or pressure loss occurs shortly after the pressure rises, the system will stop injecting slurry into the middle section of the borehole to prevent a large amount of slurry from flowing into the borehole or roadway, and will issue an audible and visual alarm to indicate that the middle section of the borehole is under pressure. At this time, the gas concentration in a single borehole can be measured first. If the gas concentration in a single borehole does not decrease significantly, no action is needed. If the gas concentration in the borehole has decreased significantly compared to before, the borehole sealer can be retrieved, and the sealing position of the sealer or the density and viscosity of the sealing slurry in the middle section can be adjusted before resealing. If it is still difficult to maintain pressure, it proves that there are serious and large fractures around the borehole that are difficult to seal. The borehole can be closed to prevent the overall gas concentration in the extraction pipeline from decreasing due to gas leakage in the borehole.

[0021] The solid material is a gel powder, which is prepared by the following steps:

[0022] (1) Mix and crush the three solid raw materials, seaweed, starch and fruit pomace, into mixed residues. The weight ratio of seaweed, starch and fruit pomace is 3:5:8.

[0023] (2) Put the mixed residue into boiling water at 100°C, boil for 30 minutes, add hydrochloric acid and stir slowly to adjust the pH of the mixed residue solution to 3;

[0024] (3) Separate the mixed residue solution to obtain a gel extract;

[0025] (4) The gel extract was concentrated by ultrafiltration at 45°C and 0.2 MPa to obtain a concentrated gel extract;

[0026] (5) The gel concentrate is dried at a feed temperature of 150°C and a discharge temperature of 220°C. The solid powder obtained by grinding after drying is the gel dry powder.

[0027] By adopting the above technical solution, the present invention has the following technical effects:

[0028] 1. The control system in this invention includes a main PLC controller and a host computer. The main PLC controller is mainly responsible for controlling the stirring motor, grouting pump station and solenoid valve to perform corresponding actions based on the requirements of pulping, grouting, and grouting and the information fed back by the flow sensor, density sensor, viscosity sensor and liquid level sensor. It also displays the relevant information on the display screen of the host computer and can adjust key data such as pulping volume, grouting volume and grouting volume as needed.

[0029] 2. During pulping, the main control PLC controller controls the water injection volume in the water supply pipe and the material discharge volume in the silo based on the pulping volume and concentration. Density and viscosity sensors are installed at corresponding positions in the mixing tank to measure the viscosity and density information of the slurry in real time and transmit it to the main control PLC controller. The automatic feeding device will add a certain amount of pulping material to the water-filled mixing tank according to the slurry volume and density information set by the main control PLC controller.

[0030] 3. A touch screen is installed in the tunnel to monitor each reusable cylindrical rubber bladder sealing device. The touch screen displays various information about the boreholes in the group, including borehole number, pressure value inside the bladder, pressure value in the middle section, grouting volume in the bladder section, and grouting volume in the middle section. The flow sensor, pressure sensor, and solenoid valve on the grouting pipe are connected to the touch screen through signal control lines. The solenoid valve can be manually or automatically controlled according to the pressure and flow information. It can collect information on the grouting volume and pressure of the bladders in each borehole in the group and the grouting volume in the middle section between two bladders, provide early warning for boreholes with pressure loss, and transmit all information to the main control PLC controller.

[0031] 4. The flexible sealing and dynamic pressure-holding sealing of the borehole ensures that the entire borehole is always in a stable pressure-holding extraction state, eliminating the air leakage caused by the increase in borehole volume after the traditional sealing material solidifies, and the failure of extraction borehole caused by the compression and breakage of the extraction tube due to the decrease in borehole volume. This ensures the safety and efficiency of extraction.

[0032] 5. The role of fruit pomace in solid materials is to extract pectin, a hydrophilic plant gum that is water-soluble. Seaweed contains a natural polysaccharide, sodium alginate, which has the ability to concentrate solutions, form gels, and form films, serving as a thickener, stabilizer, and gelling agent. Starch is used as a thickener and water-retaining agent to increase the solids content; it has good water retention, high temperature resistance, and good compatibility, and can be used simultaneously with other thickeners. After mixing seaweed, starch, and fruit pomace, a defatting reaction occurs, resulting in a gelled dry powder with good pressure resistance, good stability, minimal powder deformation, high gel strength, good viscosity, good flowability, and high surface tension.

[0033] Flexible grouting sealing material, formed by mixing solid materials with water, is a viscous material with good flowability. When the borehole deforms and cracks around the borehole wall expand, the flexible grouting material can flow into the cracks and effectively fill them under grouting pressure. It deforms with the borehole, adapting to arbitrary deformation of the borehole and maintaining close contact with the borehole wall to prevent air leakage and grout leakage.

[0034] In summary, this invention involves preparing the slurry on the ground and directly delivering it to a reusable cylindrical rubber bladder sealer inside each borehole in the underground roadway. The control system enables highly intelligent grouting and sealing, allowing for precise and free control of the sealing pressure and automatic pressure maintenance throughout the borehole sealing process. It has advantages such as small footprint, simple operation, high degree of automation, low labor intensity for workers, and cost savings. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the connection structure between the ground pulping and storage system and the conveying pipeline in this invention;

[0036] Figure 2 This is a schematic diagram of the reusable cylindrical rubber bladder sealer in this invention.

[0037] Figure 3 yes Figure 2 Axial cross-sectional view of two cylindrical rubber bladders;

[0038] Figure 4 This is a schematic diagram of the reusable cylindrical rubber bladder sealing device of the present invention arranged along the length of the tunnel in the cross-layer borehole.

[0039] Figure 5 This is a schematic diagram of the reusable cylindrical rubber bladder sealing device of the present invention arranged along the length of the roadway in the in-seam borehole. Detailed Implementation

[0040] like Figures 1-5 As shown, the flexible pressure-maintaining intelligent sealing method for underground gas drainage boreholes in coal mines of the present invention includes the following steps:

[0041] (1) A surface slurry preparation and storage system and a main control PLC controller (not shown) are arranged on the surface of the mine. A grouting pump station 2 is arranged in the underground roadway. A cylindrical rubber bladder reusable sealing device 4 is installed in several sets of gas extraction boreholes 17 in the underground roadway. The outlet of the surface slurry preparation and storage system is connected to the inlet of the grouting pump station 2 through the main slurry input pipe 1. The outlet of the grouting pump station 2 is connected to the inlet of each set of cylindrical rubber bladder reusable sealing devices 4 through the underground slurry input main pipe 3.

[0042] (2) Preparation of sealing slurry using a ground-based slurry preparation and storage system;

[0043] (3) Grouting and sealing operation is carried out in the reusable sealing device 4 of the cylindrical rubber bladder;

[0044] (4) Connect the gas extraction pipeline to the gas extraction borehole 17 for gas extraction operation;

[0045] (5) During the gas extraction operation, the cylindrical rubber bladder reusable sealing device 4 is dynamically pressure maintained, and the sealing section is monitored in real time. When the sealing section loses pressure, an alarm is triggered and measures are taken.

[0046] The ground pulping and storage system includes a silo 5, a mixing tank 6, and a belt conveyor 7. The feed end of the belt conveyor 7 is located below the discharge port of the silo 5. The top of the mixing tank 6 is provided with a feed port. The discharge end of the belt conveyor 7 is connected to the feed port through a transfer guide plate 8. The top of the mixing tank 6 is provided with a mixing motor 9. The main shaft of the mixing motor 9 is driven to connect to an agitator 10 (including a mixing shaft and blades) located inside the mixing tank 6. A water supply pipe 11 is connected to the upper side of the mixing tank 6. A water supply solenoid valve 12 and a first flow sensor 13 are provided on the water supply pipe 11. A density sensor 14 and a viscosity sensor 15 are provided on the lower part of the inner wall of the mixing tank 6. Liquid level sensors 16 are provided on both the upper and lower parts of the inner wall of the mixing tank 6.

[0047] Several gas extraction boreholes 17 are drilled in the underground roadway 37. A group of gas extraction boreholes 17 are evenly spaced along the length of roadway 37. Each borehole 17 contains a reusable cylindrical rubber bladder sealer 4. Each reusable cylindrical rubber bladder sealer 4 includes a first cylindrical rubber bladder 18, a second cylindrical rubber bladder 19, an internal grouting pipe 20, and an inter-bladder grouting pipe 21. A extraction pipe 22 is inserted into the central hole of the first cylindrical rubber bladder 18 and the second cylindrical rubber bladder 19. The first cylindrical rubber bladder 18... 8 is located below the second cylindrical rubber sac 19. The grouting tube 20 inside the sac passes through the first cylindrical rubber sac 18 and the second cylindrical rubber sac 19 from bottom to top. The upper end of the grouting tube 20 inside the sac is sealed. The grouting tube 20 inside the sac is provided with a first grouting hole 23 inside the first cylindrical rubber sac 18 and a cylindrical grouting hole 24 inside the second cylindrical rubber sac 19. The upper end of the grouting tube 21 between the sacs passes through the first cylindrical rubber sac 18 from bottom to top and extends between the first cylindrical rubber sac 18 and the second cylindrical rubber sac 19.

[0048] The lower end of the grouting pipe 20 inside the fetal sac is connected to the downhole slurry input main pipe 3 through the first grouting hose 25, and the lower end of the grouting pipe 21 between the fetal sacs is connected to the downhole slurry input main pipe 3 through the second grouting hose 26.

[0049] The lower part of the grouting tube 20 inside the fetal sac is provided with a first pressure sensor 27, a second flow sensor 28 and a first solenoid valve 29 from top to bottom; the lower part of the grouting tube 21 between the fetal sacs is provided with a second pressure sensor 30, a third flow sensor 31 and a second solenoid valve 32 from top to bottom.

[0050] The downhole slurry input main pipe 3 is equipped with a third solenoid valve 33, a fourth flow sensor 34 and a third pressure sensor 35 in sequence along the slurry flow direction, and a fourth solenoid valve 36 is provided on the slurry main input pipe 1.

[0051] Step (2) The specific process of pulping on the ground is as follows: According to the predetermined pulping amount, the main control PLC controller sends an instruction to the water supply pump connected to the inlet of the water supply pipe 11. At the same time, the belt conveyor 7, the stirring motor 9, and the screw feeder at the bottom of the silo 5 are all started, and the water supply solenoid valve 12 is opened to inject a certain amount of water into the mixing tank 6. According to the information of the first flow sensor 13, the predetermined water volume is determined and the water injection is stopped. The screw feeder quantitatively transports the solid material to the belt conveyor 7. The belt conveyor 7 transports the solid material to the mixing tank 6. The stirring motor 9 drives the stirrer 10 to start stirring, so that the solid material and water (the weight ratio of solid material and water is preferably 1:10) are fully mixed and stirred evenly until the predetermined ratio is reached. The sealing material has good fluidity and a certain viscosity. The density sensor 14 and the viscosity sensor 15 are used to measure the viscosity and density information of the slurry in real time and transmit it to the main control PLC controller. After the slurry is qualified, the stirring motor 9 stops working. The solid material is gel dry powder, which is made by the following steps:

[0052] (1) Mix and crush the three solid raw materials, seaweed, starch and fruit pomace, into mixed residues. The weight ratio of seaweed, starch and fruit pomace is 3:5:8.

[0053] (2) Put the mixed residue into boiling water at 100°C, boil for 30 minutes, add hydrochloric acid and stir slowly to adjust the pH of the mixed residue solution to 3;

[0054] (3) Separate the mixed residue solution to obtain a gel extract;

[0055] (4) The gel extract was concentrated by ultrafiltration at 45°C and 0.2 MPa to obtain a concentrated gel extract;

[0056] (5) The gel concentrate is dried at a feed temperature of 150°C and a discharge temperature of 220°C. The solid powder obtained by grinding after drying is the gel dry powder.

[0057] The specific process of step (3) is as follows: According to the number of borehole groups, the cylindrical rubber reusable sealing device 4 with the corresponding interface reserved is fixed in parallel on one side of the roadway, and connected to the underground slurry input main pipe 3 through the first grouting hose 25 and the second grouting hose 26. The cylindrical rubber reusable sealing device 4 is inserted into the borehole 17 to the predetermined sealing depth. The fourth solenoid valve 36 and the third solenoid valve 33 are opened, the grouting pump station 2 is started, and the slurry is transported to the grouting pipe of the cylindrical rubber reusable sealing device 4 at each sealing location through the slurry main input pipe 1 and the underground slurry input main pipe 3. The main control PLC controller sends a pressure signal value through the third pressure sensor 35 to control the third solenoid valve 33 on the underground slurry input main pipe 3 to realize the pipeline opening and closing, so that the underground slurry input main pipe 3 always maintains a certain grouting pressure. Subsequently, the main control PLC controller issues a sealing command. At this time, the first solenoid valve 29 on the grouting pipe 20 inside the bladder opens, and grout begins to be injected into the two first cylindrical rubber bladders 18 and the second cylindrical rubber bladder 19 through the first grouting hose 25 and the grouting pipe 20 inside the bladder. When the first pressure sensor 27 detects that the set pressure value has been reached, the first solenoid valve 29 closes, stopping the grouting. Then, the second solenoid valve 32 on the grouting pipe 21 between the bladders opens, and grout begins to be injected into the middle section between the first cylindrical rubber bladder 18 and the second cylindrical rubber bladder 19 through the second grouting hose 26 and the grouting pipe 21 between the bladders, until the second pressure sensor 30 detects that the preset grouting pressure value has been reached. The main control PLC controller then issues a command to close the second solenoid valve 32, stopping the grouting. The sealing of one borehole 17 is then completed. The same operation process is used to complete the sealing operation of the other boreholes 17 in the same group.

[0058] Step (5) The specific process of dynamically maintaining pressure on the reusable sealing device for the cylindrical rubber bladder is as follows: Taking a single extraction borehole 17 as an example, when the borehole 17 deforms and the cross-section becomes larger, causing the pressure in the first cylindrical rubber bladder 18 and / or the second cylindrical rubber bladder 19 to decrease and become less than the predetermined constant pressure, the first pressure sensor 27 transmits the pressure monitoring data to the main control PLC controller. The main control PLC controller instructs the first solenoid valve 29 to open, and the grouting pipe 20 inside the bladder begins to inject grout into the two first cylindrical rubber bladders 18 and the second cylindrical rubber bladder 19. When the first pressure sensor 27 detects that the set pressure value has been reached, the first solenoid valve 29 closes and stops grouting. Similarly, when the pressure drops in the middle section between the first cylindrical rubber bladder 18 and the second cylindrical rubber bladder 19 due to the continuous seepage of grout into the cracks around the borehole 17, the second solenoid valve 32 connected to the grouting pipe 21 between the bladders opens, and the grout begins to be injected into the middle section between the first cylindrical rubber bladder 18 and the second cylindrical rubber bladder 19 through the grouting pipe 21 until the second pressure sensor 30 detects that the preset grouting pressure value has been reached. The main control PLC controller then issues a command to close the second solenoid valve 32 to stop the grouting.

[0059] When borehole 17 deforms and its effective diameter decreases due to mining activities, the pressure on the first cylindrical rubber bladder 18, the second cylindrical rubber bladder 19, and the intermediate section increases. Since the first cylindrical rubber bladder 18 and the second cylindrical rubber bladder 19 are made of highly elastic rubber, they can withstand greater pressure, thus significantly improving the sealing effect. When the first pressure sensor 27 and the second pressure sensor 30 detect pressures exceeding the limit pressure that the first cylindrical rubber bladder 18 and the second cylindrical rubber bladder 19 can withstand, the main control PLC controller issues a command to open the first solenoid valve 29 and the second solenoid valve 32. The slurry inside the first cylindrical rubber bladder 18, the second cylindrical rubber bladder 19, and the intermediate section can flow back into the downhole slurry input main pipe 3 until the pressure is balanced with the slurry pressure in the downhole slurry input main pipe 3, at which point the first solenoid valve 29 and the second solenoid valve 32 close.

[0060] The specific process of real-time monitoring of the sealing section and alarm and handling when the sealing section loses pressure in step (5) is as follows:

[0061] A) Alarm and handling process for pressure loss of cylindrical rubber bladder: When the cylindrical rubber bladder ruptures and causes instantaneous grout leakage, resulting in a sharp drop in pressure monitored by the first pressure sensor 27, and the injection of grout cannot maintain the pressure of the cylindrical rubber bladder, or when the pressure rises and then drops shortly, the system will stop injecting grout into the cylindrical rubber bladder to prevent a large amount of grout from flowing into borehole 17 or tunnel 37, and will issue an audible and visual alarm to indicate that the cylindrical rubber bladder in borehole 17 has lost pressure and ruptured. At this time, the cylindrical rubber bladder in borehole 17 can be recovered first, the damaged cylindrical rubber bladder can be replaced, and then the borehole can be sealed to ensure that the borehole 17 can continue to be pumped normally.

[0062] B) Alarm and Handling Process for Pressure Loss in the Middle Section: When a large number of through-type fractures appear in the middle section of the borehole due to mining, resulting in severe slurry loss in the middle section, the pressure monitored by the second pressure sensor 30 drops sharply, and the injection of slurry cannot maintain the pressure in the middle section, or pressure loss occurs shortly after the pressure rises, the system will stop injecting slurry into the middle section of the borehole to prevent a large amount of slurry from flowing into borehole 17 or roadway 37, and issue an audible and visual alarm to indicate that the middle section of the borehole is under pressure. At this time, the gas concentration in a single borehole of borehole 17 can be measured first. If the gas concentration in a single borehole does not decrease significantly, no action is required. If the gas concentration in borehole 17 decreases too much compared to before, the sealing device of borehole 17 can be retrieved, the sealing position of the sealing device or the density and viscosity of the sealing slurry in the middle section can be adjusted, and the borehole can be sealed again. If it is still difficult to maintain pressure, it proves that there are serious and large cracks around the borehole 17 that are difficult to seal. The borehole 17 can be closed to prevent the overall gas concentration of the extraction pipeline from decreasing due to gas leakage from the borehole 17.

[0063] The flexible sealing and dynamic pressure-holding sealing of borehole 17 ensures that the entire borehole 17 is always in a stable pressure-holding extraction state, eliminating the air leakage caused by the increase in volume of borehole 17 after the solidification of traditional sealing materials, and the failure of extraction borehole 17 caused by the compression and breakage of extraction tube due to the decrease in volume of borehole 17. This ensures the safety and efficiency of extraction.

[0064] The automatic control of the solenoid valve by the main PLC controller in this invention, as well as the pressure, flow rate, liquid level, viscosity and other signals received by the main PLC controller, do not involve new computer programs.

[0065] This embodiment does not impose any limitation on the shape, material, structure, etc. of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A flexible pressure maintaining and intelligent hole sealing method for gas extraction drilling in a coal mine underground, characterized in that: The method comprises the following steps: (1) arranging a ground slurry preparation and storage system and a main control PLC controller on the ground of a mine, arranging a grouting pump station in a roadway underground, and arranging a cylindrical rubber tire bag reusable hole sealing device in a plurality of groups of gas extraction boreholes in the roadway underground, connecting a liquid outlet of the ground slurry preparation and storage system with a liquid inlet of the grouting pump station through a slurry main input pipe, and connecting a liquid outlet of the grouting pump station with a liquid inlet of each cylindrical rubber tire bag reusable hole sealing device through an underground slurry input main pipe; (2) preparing a hole sealing slurry by the ground slurry preparation and storage system; (3) performing a grouting and hole sealing operation in the cylindrical rubber tire bag reusable hole sealing device, wherein the cylindrical rubber tire bag reusable hole sealing device comprises a first cylindrical rubber tire bag, a second cylindrical rubber tire bag, an inner bag grouting pipe and an inter-bag grouting pipe, a lower end of the inner bag grouting pipe is connected with the underground slurry input main pipe through a first grouting hose, a lower end of the inter-bag grouting pipe is connected with the underground slurry input main pipe through a second grouting hose, a first pressure sensor, a second flow sensor and a first electromagnetic valve are sequentially arranged in the lower part of the inner bag grouting pipe from top to bottom, and a second pressure sensor, a third flow sensor and a second electromagnetic valve are sequentially arranged in the lower part of the inter-bag grouting pipe from top to bottom; (4) connecting a gas extraction pipeline to perform a gas extraction operation on the gas extraction borehole; (5) performing dynamic pressure maintaining on the cylindrical rubber tire bag reusable hole sealing device during the gas extraction operation, and performing real-time monitoring on the hole sealing section, and performing alarm and disposal when the hole sealing section loses pressure; The specific process of performing dynamic pressure maintaining on the cylindrical rubber tire bag reusable hole sealing device comprises: When the borehole is deformed due to mining and the effective diameter of the borehole becomes smaller, the pressure borne by the first cylindrical rubber tire bag, the second cylindrical rubber tire bag and the middle section will become larger, the first cylindrical rubber tire bag and the second cylindrical rubber tire bag are made of rubber with good elasticity and can bear larger pressure, and therefore the hole sealing effect can be greatly improved at this time, When the first pressure sensor and the second pressure sensor monitor that the pressure is greater than the limit pressure borne by the first cylindrical rubber tire bag and the second cylindrical rubber tire bag, the main control PLC controller sends an instruction to open the first electromagnetic valve and the second electromagnetic valve, the slurry in the first cylindrical rubber tire bag, the second cylindrical rubber tire bag and the middle section can flow back to the underground slurry input main pipe, and the first electromagnetic valve and the second electromagnetic valve are closed until the pressure of the slurry in the underground slurry input main pipe is balanced.

2. The flexible pressure maintaining and intelligent hole sealing method for coal mine underground gas extraction drilling according to claim 1, characterized in that: The ground slurry preparation and storage system comprises a stock bin, a stirring barrel and a belt conveyor, the feeding end of the belt conveyor is located below the discharge port of the stock bin, the top of the stirring barrel is provided with a feeding port, the discharge end of the belt conveyor is connected with the feeding port through a transfer guide plate, the top of the stirring barrel is provided with a stirring motor, the stirring motor main shaft is drivingly connected with a stirrer arranged in the stirring barrel, the upper side of the stirring barrel is connected with a water supply pipe, the water supply pipe is provided with a water supply electromagnetic valve and a first flow sensor, the inner wall of the stirring barrel is provided with a density sensor and a viscosity sensor at the lower part, and the inner wall of the stirring barrel is provided with liquid level sensors at the upper part and the lower part.

3. The flexible pressure maintaining and intelligent hole sealing method for underground coal mine gas extraction drilling according to claim 2, characterized in that: The gas extraction drillings in the underground roadway are provided with a plurality of drilling holes, wherein the gas extraction drilling holes arranged uniformly along the length direction of the roadway are a group, and one cylindrical rubber tire capsule reusable hole sealing device is arranged in each group of drilling holes; one extraction pipe is inserted into the central holes of the first cylindrical rubber tire capsule and the second cylindrical rubber tire capsule, the first cylindrical rubber tire capsule is located below the second cylindrical rubber tire capsule, a grouting pipe in the tire capsule passes through the first cylindrical rubber tire capsule and the second cylindrical rubber tire capsule from bottom to top in sequence, the upper end of the grouting pipe in the tire capsule is blocked, the grouting pipe in the tire capsule is provided with a first grouting hole located in the first cylindrical rubber tire capsule and a cylindrical grouting hole in the tire capsule located in the second cylindrical rubber tire capsule, and the upper end of the grouting pipe between the tire capsules passes through the first cylindrical rubber tire capsule from bottom to top and then extends into the space between the first cylindrical rubber tire capsule and the second cylindrical rubber tire capsule.

4. The flexible pressure maintaining and intelligent hole sealing method for underground coal mine gas extraction drilling according to claim 3, characterized in that: The third electromagnetic valve, the fourth flow sensor and the third pressure sensor are sequentially arranged on the slurry input main pipe along the slurry flow direction.

5. The flexible pressure maintaining and intelligent hole sealing method for underground coal mine gas extraction drilling according to claim 4, characterized in that: The specific process of step (2) is as follows: according to the predetermined slurry preparation amount, the main control PLC controller sends a command to the water supply pump connected to the water supply pipe inlet, and at the same time, the command starts the belt conveyor, the stirring motor and the screw feeder at the lower part of the silo, the water supply electromagnetic valve is opened, a certain amount of water is injected into the stirring barrel, the water injection is stopped according to the information of the first flow sensor, the screw feeder quantitatively delivers the solid materials to the belt conveyor, the belt conveyor delivers the solid materials to the stirring barrel, the stirring motor drives the stirrer to start stirring, so that the solid materials and water are fully mixed and stirred uniformly until the predetermined proportion is reached, forming a slurry with good fluidity and certain viscosity, the density sensor and the viscosity sensor are used to determine the viscosity and density information of the slurry in real time and transmit them to the main control PLC controller, and the stirring motor stops working after the slurry is qualified.

6. The flexible pressure maintaining and intelligent hole sealing method for coal mine underground gas extraction drilling according to claim 5, characterized in that: The specific process of step (3) is: according to the number of drill hole groups, the cylindrical rubber tire capsule reusable hole sealers with reserved corresponding interfaces are fixed side by side on the roadway one side, and are connected with the underground slurry input main pipe through the first and second grouting hoses, the cylindrical rubber tire capsule reusable hole sealers are inserted into the drill hole to the predetermined hole sealing depth; the main control PLC controller instructs the fourth and third electromagnetic valves to open, and the grouting pump station starts, the slurry is transported to the grouting pipe of the cylindrical rubber tire capsule reusable hole sealer at each hole sealing position through the slurry main input pipe and the underground slurry input main pipe, the main control PLC controller sends a pressure signal value through the third pressure sensor to control the third electromagnetic valve on the underground slurry input main pipe to realize the opening and closing of the pipeline, so that a certain grouting pressure is maintained in the underground slurry input main pipe at all times; then the main control PLC controller sends a hole sealing instruction, at this time the first electromagnetic valve on the grouting pipe in the tire capsule opens, the slurry starts to be injected into the two first cylindrical rubber tire capsules and the second cylindrical rubber tire capsule through the first grouting hose and the grouting pipe in the tire capsule, when the first pressure sensor monitors the set pressure value, the first electromagnetic valve is closed to stop grouting, then the second electromagnetic valve on the inter-tire capsule grouting pipe opens, the slurry starts to be injected into the middle section between the first cylindrical rubber tire capsule and the second cylindrical rubber tire capsule through the second grouting hose and the inter-tire capsule grouting pipe, until the second pressure sensor monitors the preset grouting pressure value, the main control PLC controller sends a second electromagnetic valve closing instruction to stop grouting, and the hole sealing of one drill hole is completed, The hole sealing operation of other drill holes in the group is completed by using the same operation process.

7. The flexible pressure maintaining and intelligent hole sealing method for coal mine underground gas extraction drilling according to claim 6, characterized in that: The specific process of step (5) for dynamic pressure maintaining of the cylindrical rubber tire capsule reusable hole sealer further includes: when the drill hole deforms and the cross section becomes larger, thereby causing the pressure in the first cylindrical rubber tire capsule and / or the second cylindrical rubber tire capsule to become smaller and less than the predetermined constant pressure, the first pressure sensor transmits pressure monitoring data to the main control PLC controller, the main control PLC controller instructs the first electromagnetic valve to open, and the grouting pipe in the tire capsule starts to supplement the slurry into the two first cylindrical rubber tire capsules and the second cylindrical rubber tire capsule, when the first pressure sensor monitors the set pressure value, the first electromagnetic valve is closed to stop grouting; similarly, when the pressure in the middle section between the first cylindrical rubber tire capsule and the second cylindrical rubber tire capsule decreases due to the emergence of cracks around the drill hole and the continuous seepage of slurry into the cracks, the second electromagnetic valve connected to the inter-tire capsule grouting pipe opens, the slurry starts to supplement into the middle section between the first cylindrical rubber tire capsule and the second cylindrical rubber tire capsule through the inter-tire capsule grouting pipe, until the second pressure sensor monitors the preset grouting pressure value, the main control PLC controller sends a second electromagnetic valve closing instruction to stop grouting.

8. The flexible pressure maintaining and intelligent hole sealing method for coal mine underground gas extraction drilling according to claim 7, characterized in that: The specific process of step (5) for real-time monitoring of the hole sealing section, alarm and disposal when the pressure of the hole sealing section is lost is: A) Cylinder rubber tire capsule pressure loss alarm and disposal process: when the cylinder rubber tire capsule is damaged and the first pressure sensor monitoring pressure drops sharply, the slurry cannot be injected into the cylinder rubber tire capsule, or the pressure rises and the pressure loss occurs in a short time, the system will stop injecting slurry into the cylinder rubber tire capsule, prevent the slurry from flowing into the borehole or roadway, and issue an audible and visual alarm, prompting the cylinder rubber tire capsule in the borehole to lose pressure and be damaged. At this time, the cylinder rubber tire capsule in the borehole is recovered, and the damaged cylinder rubber tire capsule is replaced, and then the hole sealing operation is carried out, which can ensure that the borehole continues to operate normally. B) Intermediate section pressure loss alarm and disposal: when the intermediate section of the borehole is affected by mining and a large number of through cracks occur, causing serious slurry loss in the intermediate section of the borehole, the second pressure sensor monitoring pressure drops sharply, and the slurry cannot be injected into the intermediate section of the borehole, or the pressure rises and the pressure loss occurs in a short time, the system will stop injecting slurry into the intermediate section of the borehole, prevent the slurry from flowing into the borehole or roadway, and issue an audible and visual alarm, prompting the intermediate section of the borehole to lose pressure. At this time, the gas concentration in the single borehole is measured, and if the gas concentration in the single borehole does not decrease significantly, it is not treated. If the gas concentration in the borehole decreases significantly, the hole sealing device is recovered, the sealing position of the hole sealing device is adjusted, or the density and viscosity of the intermediate section sealing slurry are adjusted, and the hole is sealed again. If it is still difficult to maintain pressure, it is proved that there are serious large cracks around the borehole, which are difficult to seal, and the borehole is closed to prevent the borehole from leaking and causing the overall gas concentration in the extraction pipeline to decrease.

9. The flexible pressure maintaining and intelligent hole sealing method for underground coal mine gas extraction drilling according to claim 5, characterized in that: The solid material is a gel dry powder, which is prepared by the following steps: (1) Mix and crush seaweed, starch and pomace to obtain mixed crushed residues, and the weight ratio of seaweed, starch and pomace is 3:5:8; (2) Put the mixed crushed residues into boiling water at 100℃, cook for 30min, add hydrochloric acid, and slowly stir to adjust the ph of the mixed crushed residue solution to 3; (3) Separate the mixed crushed residue solution to obtain a gel extract; (4) Concentrate the gel extract by ultrafiltration at 45℃ and 0.2Mpa pressure to obtain a gel concentrate; (5) Dry the gel concentrate under the conditions of feed temperature 150℃ and discharge temperature 220℃, and grind the dried solid powder to obtain a gel dry powder.

Images