Pressure relief hole gas extraction pipeline applying foamed metal

Abstract

The utility model relates to a pressure relief hole gas extraction pipeline applying foamed metal, belongs to the technical field of underground gas extraction of coal mine, including the hole protection casing pipe, the hole protection casing pipe is located in the extraction borehole, and the hole protection casing pipe one end is connected with the connecting pipe one end through the reducing diameter towards the orifice, the other end of connecting pipe is equipped with the extraction system pipeline, and the connecting pipe is fixed on the extraction borehole through the hole sealing bag near the orifice end and near the reducing diameter end, the long recess in the outer surface of hole protection casing pipe is equipped with the optical fiber directly contacted with coal seam, and the optical fiber is connected with the collection control system. The hole protection casing pipe adopts foamed metal material and has porous structure, provides the passage for gas flow, guarantees the gas concentration stability in the extraction system, the hole protection casing pipe has strong energy absorption capacity under the influence of impact ground pressure and is automatically deformed, plays the anti -impact effect to the coal seam, guarantees the engineering progress, avoids the repeated punching and wastes manpower and material resources.

Description

Technical Field

[0001] This invention belongs to the field of underground gas extraction technology in coal mines, specifically relating to a gas extraction pipeline with pressure relief holes using foamed metal. Background Technology

[0002] With the increase in mine depth and the continuous improvement of mechanization and mining capacity, mining speed and efficiency have been greatly improved. In the process of efficient tunneling and mining, higher requirements have been placed on effective gas control and precise prevention of dynamic disasters. When mining coal seams with strong rockburst tendency, the combination of multiple factors such as periodic pressure and thick bottom coal during the working face mining period leads to significant mine pressure manifestation, severe deformation, and frequent micro-vibration events, resulting in abnormal and large-volume gas outbursts. Traditional gas control methods cannot meet the safety production requirements of the working face, and a reasonable method is urgently needed to manage the combined dynamic disasters of gas and rockburst. Currently, using borehole drainage to relieve gas pressure is one of the most commonly used methods in coal mines, and the technology is relatively mature. For the prevention and control of rockbursts, large-diameter borehole drainage technology is usually adopted. Pre-mining pre-drainage boreholes are arranged vertically to the coal wall in both roadways of the working face, and the mine anti-rockburst and pressure-relieving drilling project is also implemented in the roadways.

[0003] The following problems exist in actual engineering:

[0004] The gas concentration attenuates rapidly during extraction, and extraction holes in soft coal seams are prone to collapse, causing extraction hole failure. If PVC casing is used to solidify the hole, it is not conducive to the release of gas from the coal body into the borehole. The PVC casing is made of the same material throughout the hole, and the compressive load is a fixed value. Once the stress in the coal seam changes, the extraction hole will be compacted, which can also easily cause extraction failure. The anti-impact and pressure relief methods for large-diameter boreholes have a long construction cycle and are prone to repeated construction with extraction boreholes, which consumes manpower and resources. Neither extraction holes nor pressure relief holes can monitor the condition inside the hole in real time. Summary of the Invention

[0005] The purpose of this invention is to provide a gas extraction pipeline with a pressure relief hole using foamed metal, which can serve two purposes in one hole. It can ensure both gas extraction and anti-impact pressure relief, and can also achieve intelligent monitoring. This will greatly reduce the amount of drilling work, shorten the drilling construction cycle, save manpower and material resources, and ensure safe production in coal mines.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A gas extraction pipeline for a pressure relief hole using foamed metal includes a protective sleeve located inside the extraction borehole. The end of the protective sleeve facing the borehole opening is connected to one end of a connecting pipe via a reducer. The other end of the connecting pipe is equipped with an extraction system pipeline. The connecting pipe is fixed to the extraction borehole by sealing bags at the ends near the borehole opening and near the reducer. An optical fiber that is in direct contact with the coal seam is installed in a long groove on the outer surface of the protective sleeve, and the optical fiber is connected to the acquisition and control system.

[0008] The protective sleeve is made of foamed metal material and has internal and external threads machined at both ends for connecting the protective sleeve.

[0009] The protective sleeve includes a low-stress section, a concentrated stress section, and a medium-stress section; wherein the compressive load of the low-stress section is P0, the compressive load of the concentrated stress section is P1, and the compressive load of the medium-stress section is P2, and P1>P2>P0.

[0010] The extraction boreholes are divided into two types: a reference borehole and a regular borehole. The outer surface of the protective sleeve in the reference borehole is machined with a long groove 0.5mm wide and 0.5mm deep and set along the axial direction. The optical fiber is inserted into the long groove of the protective sleeve. No optical fiber is installed on the protective sleeve in the regular borehole.

[0011] Multiple sets of extraction boreholes are radially arranged along the tunnel excavation direction. A set of extraction boreholes consisting of a reference borehole and four ordinary boreholes is constructed sequentially along the tunnel excavation direction. The diameter of the reference borehole and the ordinary boreholes is larger than the outer diameter of the casing.

[0012] Using the fiber grating drift on the borehole casing as a reference, the lengths of the low-stress section, concentrated stress section, and medium-stress section of the casing are calculated, and the casing for each part is made using foam metal with different densities.

[0013] The data acquisition and control system includes a computer connected to a parameter acquisition instrument via wires. The parameter acquisition instrument is connected to a gas concentration sensor, an electronic flow meter, an electric ball valve, and an optical fiber. The gas concentration sensor, electronic flow meter, and electric ball valve are sequentially installed on a connecting pipe, and a manual valve is installed on the connecting pipe between the gas concentration sensor and the extraction system pipeline. The parameter acquisition instrument is fixed to the wall of the working face roadway. The gas concentration sensor, electronic flow meter, and optical fiber constitute an information monitoring module, the microcontroller in the parameter acquisition instrument is an information processing module, and the electric ball valve and computer are information output modules.

[0014] The parameter acquisition instrument analyzes the gas concentration and flow rate within the extraction borehole, calculating the pure gas concentration by multiplying the concentration by the flow rate. When the pure gas concentration detected within the extraction borehole is less than 0.5 m³, the instrument is activated. 3When the flow rate is reduced by 0.1 m³ / min, the negative pressure in the adjusting orifice of the electric ball valve is set to half of its original value; subsequently, for every 0.1 m³ / min decrease in the pure flow rate... 3 / min, the negative pressure will decrease by 1kPa until the pure gas content in the extraction borehole is 0. Then, close the manual valve to stop the negative pressure extraction and prevent gas leakage from the extraction borehole.

[0015] The technical effects of this invention are as follows:

[0016] The borehole casing is made of foamed metal with a porous structure, providing a channel for gas flow and ensuring stable gas concentration within the extraction system. The foamed metal has strong energy absorption capabilities, and the casing automatically deforms under the influence of rockbursts, relieving pressure on the coal seam and preventing rockbursts. This ensures project progress and avoids wasting manpower and resources through repeated drilling. Fiber optic monitoring of the casing deformation provides timely warnings before dynamic disasters occur. Based on gas concentration and flow parameters, intelligent control of the extraction negative pressure improves extraction purity and efficiency. Attached Figure Description

[0017] Figure 1 Schematic diagram of a gas extraction pipeline with pressure relief holes using foamed metal in this invention;

[0018] Figure 2 A partial schematic diagram of the protective sleeve of this invention;

[0019] Figure 3 This invention refers to schematic diagrams of borehole and conventional borehole arrangements;

[0020] 1-Gas extraction system pipeline, 2-Manual valve, 3-Gas concentration sensor, 4-Electronic flow meter, 5-Electric ball valve, 6-Computer, 7-Parameter acquisition instrument, 8-Sealing bag, 9-Connecting pipe, 10-Reducing diameter, 11-Fiber optic cable, 12-Breakhole casing, 13-Coal seam, 14-Ordinary borehole, 15-Reference borehole. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0022] like Figures 1 to 3 As shown, a gas extraction pipeline for a pressure relief hole using foamed metal includes a protective sleeve 12, which is located inside the extraction borehole. One end of the protective sleeve 12 facing the borehole opening is connected to one end of a connecting pipe 9 via a reducing diameter 10. The other end of the connecting pipe 9 is equipped with an extraction system pipeline 1. In this embodiment, the connecting pipe 9 is a PVC pipe. The end of the connecting pipe 9 near the borehole opening and the end near the reducing diameter 10 are fixed to the extraction borehole by a sealing bag 8. The borehole is sealed by a two-plug-one-injection method. An optical fiber 11 that is in direct contact with the coal seam 13 is installed in a long groove on the outer circular surface of the protective sleeve 12 along the axial direction, and the optical fiber 11 is connected to the acquisition and control system.

[0023] The protective sleeve 12 is made of foamed metal material and has internal and external threads machined at both ends for connecting adjacent protective sleeves 12. In this embodiment, the protective sleeve 12 is 2m long. The protective sleeve 12 includes a low-stress section, a concentrated stress section, and a medium-stress section; wherein, the compressive load of the low-stress section is P0, the compressive load of the concentrated stress section is P1, and the compressive load of the medium-stress section is P2, and P1>P2>P0. There are two types of extraction boreholes: a reference borehole 15 and a regular borehole 14. The outer surface of the protective sleeve 12 located in the reference borehole 15 has a long groove with a width of 0.5mm and a depth of 0.5mm, and the optical fiber 11 is inserted into the long groove of the protective sleeve 12. The protective sleeve 12 located in the regular borehole 14 does not have a long groove and does not have an optical fiber 11 installed. Multiple sets of radially arranged boreholes are drilled along the tunnel excavation direction. A extraction borehole group consisting of a reference borehole 15 and four ordinary boreholes 14 is constructed sequentially along the tunnel excavation direction. During the construction of the extraction borehole group, a large-diameter drill bit with a diameter of 153mm is used, and the outer diameter of the casing 12 is 130mm, smaller than the diameters of the reference borehole 15 and the ordinary boreholes 14. Using the grating drift of the fiber optic cable 11 on the casing 12 inside the reference borehole 15 as a reference, the lengths of the low-stress section, concentrated stress section, and medium-stress section of the casing 12 are calculated, and different densities of foam metal are used to fabricate the casing 12 for each part. The fluctuation amplitude of the grating wavelength drift increases with the increase of stress on the casing 12, and vice versa. If a sudden peak amplitude exceeds 1nm, it is judged as a precursor to a dynamic disaster, and the computer 6 issues an alarm.

[0024] The first reference borehole 15 is constructed along the tunnel excavation direction. The hardness of the protective sleeve 12 of the reference borehole 15 is selected based on the mine ground stress data. An optical fiber 11 is installed on the protective sleeve 12 installed in the reference borehole 15. After the reference borehole 15 is completed, the protective sleeve 12 with the optical fiber 11 installed is sent into the reference borehole 15. The protective sleeve 12 is connected to the connecting pipe 9 through the reducing pipe 10. One end of the optical fiber 11 is installed in the long groove of the connecting pipe 9 through the reducing pipe 10. The portion of the optical fiber 11 in the reducing pipe 10 can be fixed by wrapping with tape. Then it is connected to the parameter acquisition instrument 7. The stress distribution is calculated by monitoring the grating wavelength drift of the protective sleeve 12, which serves as the basis for selecting the hardness of the protective sleeve 12 when it is subsequently installed in the ordinary borehole 14.

[0025] The data acquisition and control system includes a parameter acquisition instrument 7. In this embodiment, the parameter acquisition instrument 7 is model YHC1. The input terminals of the parameter acquisition instrument 7 are connected to the gas concentration sensor 3, the electronic flow meter 4, and the optical fiber 11, respectively. The output terminals of the parameter acquisition instrument 7 are connected to the electric ball valve 5 and the computer 6, respectively. The parameter acquisition instrument 7 is connected to an external power supply to power the entire data acquisition and control system. The gas concentration sensor 3, the electronic flow meter 4, and the electric ball valve 5 are sequentially installed on the connecting pipe 9. A manual valve 2 is installed on the connecting pipe 9 between the gas concentration sensor 3 and the extraction system pipeline 1. The parameter acquisition instrument 7 is fixed on the wall of the working face roadway. The gas concentration sensor 3, the electronic flow meter 4, and the optical fiber 11 form an information monitoring module. The microcontroller in the parameter acquisition instrument 7 is the information processing module, and the electric ball valve 5 and the computer 6 are the information output modules. The data acquisition and control system collects data on changes in gas concentration, flow rate, and grating wavelength drift in the extraction borehole.

[0026] Gas concentration sensor 3 and electronic flow meter 4 collect gas concentration and flow information, which is then fed back to parameter acquisition instrument 7. Parameter acquisition instrument 7 analyzes the received concentration and flow information using its microcontroller circuit, integrating the concentration and flow data to derive a purity value. This purity value is used to adjust the opening and closing of electric ball valve 5. Simultaneously, the gas concentration, flow, and fiber optic detection data are compared, analyzed, and categorized with thresholds set in the microcontroller, generating corresponding anomaly alerts. For example, if the purity detected in the extraction borehole is less than 0.5 m³... 3 When the flow rate is reduced by 0.1 m³ / min, the negative pressure in the adjusting orifice of the electric ball valve 5 is set to half of its original value. Subsequently, for every 0.1 m³ / min decrease in the flow rate... 3 / min, the negative pressure decreases by 1kPa until the gas purity in the extraction borehole is 0, generating an abnormal warning message that is transmitted to the computer 6 on the ground. Then, the manual valve 2 is manually closed to stop the negative pressure extraction and prevent gas leakage from the extraction borehole. When the grating wavelength drift suddenly shows a peak value with an amplitude exceeding 1nm, it is judged as a precursor to a dynamic disaster, and the warning message is promptly transmitted to the computer 6 on the ground.

Claims

1. A gas extraction pipeline with pressure relief holes using foamed metal, characterized in that, The system includes a borehole protector sleeve located inside the extraction borehole. The end of the borehole protector sleeve facing the borehole opening is connected to one end of a connecting pipe via a reducer. The other end of the connecting pipe is equipped with an extraction system pipeline. The connecting pipe is fixed to the extraction borehole via a sealing bag at both the end near the borehole opening and the end near the reducer. An optical fiber that is in direct contact with the coal seam is installed in a long groove on the outer surface of the borehole protector sleeve, and the optical fiber is connected to the acquisition and control system. The protective sleeve is made of foamed metal material and has internal and external threads machined at both ends for connecting the protective sleeve. The protective sleeve includes a low-stress section, a concentrated stress section, and a medium-stress section; wherein, the compressive load of the low-stress section is P0, the compressive load of the concentrated stress section is P1, and the compressive load of the medium-stress section is P2, and P1>P2>P0. The extraction boreholes are divided into two types: a reference borehole and a regular borehole. The outer surface of the protective sleeve in the reference borehole is machined with an axially arranged long groove, and the optical fiber is inserted into the long groove of the protective sleeve. No optical fiber is installed on the protective sleeve in the regular borehole. The length of the low-stress section, concentrated stress section and medium-stress section of the protective sleeve is calculated with reference to the fiber grating drift on the protective sleeve in the reference borehole. The protective sleeves of each part are made of foam metal with different densities. The data acquisition and control system includes a computer, which is connected to a parameter acquisition instrument via wires. The parameter acquisition instrument is connected to a gas concentration sensor, an electronic flow meter, an electric ball valve, and an optical fiber. The gas concentration sensor, electronic flow meter, and electric ball valve are sequentially installed on a connecting pipe, and a manual valve is installed on the connecting pipe between the gas concentration sensor and the extraction system pipeline. The parameter acquisition instrument is fixed to the wall of the working face roadway. The gas concentration sensor, electronic flow meter, and optical fiber constitute an information monitoring module, the microcontroller in the parameter acquisition instrument is an information processing module, and the electric ball valve and computer are information output modules.

2. The gas extraction pipeline with pressure relief holes using foamed metal according to claim 1, characterized in that: Multiple sets of extraction boreholes are radially arranged along the tunnel excavation direction. A set of extraction boreholes consisting of a reference borehole and four ordinary boreholes is constructed sequentially along the tunnel excavation direction. The diameter of the reference borehole and the ordinary boreholes is larger than the outer diameter of the casing.

3. A gas extraction pipeline with pressure relief holes using foamed metal according to claim 1, characterized in that: The parameter acquisition instrument analyzes the gas concentration and flow rate within the extraction borehole, calculating the pure gas concentration by multiplying the concentration by the flow rate. When the pure gas concentration detected within the extraction borehole is less than 0.5 m³, the instrument is activated. 3 When the flow rate is reduced by 0.1 m³ / min, the negative pressure in the adjusting orifice of the electric ball valve is set to half of its original value; subsequently, for every 0.1 m³ / min decrease in the pure flow rate... 3 / min, the negative pressure will decrease by 1kPa until the pure gas content in the extraction borehole is 0. Then, close the manual valve to stop the negative pressure extraction and prevent gas leakage from the extraction borehole.

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