A method for measuring volume of hydraulic flushing in underground coal mine

Abstract

This invention provides a method for determining the volume of hydraulic perforation in coal mines. The method includes: closing two valves and a throttle valve; opening the air pump and valves to extract high-pressure nitrogen from the storage tank into the measuring instrument; closing the air pump and valves when the pressure in the measuring instrument reaches a preset value, and recording the nitrogen pressure P1, volume V1, and temperature T1 in the measuring instrument; opening the throttle valve to allow nitrogen in the measuring instrument to enter the measuring air chamber and expand, and observing the second pressure gauge; closing the throttle valve when the pressure reaches the later preset value of the measuring instrument, and recording the nitrogen pressure P2, volume V2, and temperature T2 in the measuring instrument; reading the second pressure gauge reading P3; inputting the data into the measuring instrument; operating the measuring instrument to calculate the volume of the perforated hole. This invention can effectively overcome errors caused by differences in coal body parameters and coal powder loss, controlling the volume measurement error to within 2%.

Description

Technical Field

[0001] This invention relates to the field of hydraulic perforation technology in coal mines, and more particularly to a method for measuring the volume of hydraulic perforation in coal mines. Background Technology

[0002] As the depth of coal mining increases year by year, coal seam mining faces the challenges of high gas content, high adsorption, and low permeability. Before mining, pressure relief and extraction are required, and hydraulic perforation is a conventional pressure relief and extraction method that is widely used.

[0003] To achieve the desired pressure relief and extraction effect, it is necessary to control the volume of hydraulic perforation. However, there is currently no suitable method for accurately measuring the volume of hydraulic perforation in underground coal mines.

[0004] Currently, there are two main methods for estimating the volume of boreholes in coal mines. One method is to make an empirical guess based on the drilling time. However, due to the significant differences in parameters and properties at different coal seam locations, and the inherently large errors in empirical judgment, the estimated volume of the borehole obtained by this method deviates greatly from the actual volume. The other method is to estimate the volume of the borehole by weighing the coal produced during drilling. However, since the coal produced during drilling flows out with the water flow, and a large amount of coal dust is mixed into the water flow, a large amount of coal is lost in the roadway with the water flow and cannot be collected. Therefore, the weighed coal mass has a large error, resulting in a distorted estimated volume of the borehole. Summary of the Invention

[0005] The purpose of this invention is to provide a method for measuring the volume of hydraulic perforation in underground coal mines, solving the problem of difficulty in calculating the volume of hydraulic perforation in underground coal mines, and providing technical support for safe coal mining.

[0006] The technical solution of this invention is: a method for measuring the volume of hydraulic perforation in coal mines, comprising the following steps: Step 1: Install the aforementioned hydraulic perforation volume measuring device in the working face. This device measures the volume of holes in the coal seam. Below the coal seam are rock strata and the working face. The device includes a measuring airbag located in the hole, a storage tank located in the working face and connected sequentially by a second air pipe, an air pump, a measuring instrument, a throttle valve, and the first port of a tee. The second port of the tee is connected to the first air pipe. A borehole is drilled within the coal seam and rock strata, with one end of the borehole connected to the hole. The end of the first air pipe furthest from the tee extends from the borehole and connects to the measuring airbag. The second air pipe has two valves located at the inlet and outlet of the air pump. The two valves and the throttle valve are closed. Step 2: Set the initial and subsequent preset values ​​for the pressure of the measuring instrument; Step 3: Turn on the air pump and valve to extract high-pressure nitrogen from the storage tank into the measuring instrument. When the pressure in the measuring instrument reaches the preset value, turn off the air pump and valve, and record the nitrogen pressure value P1, volume V1, and temperature T1 in the measuring instrument. At this time, the nitrogen in the measuring instrument satisfies the ideal gas law: (1) In the above formula, V 1 represents the volume of the measuring instrument. T 1 represents the temperature of the measuring instrument; R gN Let be the gas constant of nitrogen. m 1 represents the mass of nitrogen gas in the measuring instrument; Step four: Open the throttle valve to allow nitrogen gas in the measuring instrument to enter the measuring bladder and expand, and observe the second pressure gauge; when the pressure value reaches the preset value of the measuring instrument, close the throttle valve and record the pressure P2, volume V2, and temperature T2 of the nitrogen gas in the measuring instrument; at this time, the nitrogen gas in the measuring instrument satisfies the ideal gas law: (2) In the above formula, m 2 represents the mass of nitrogen in the measuring instrument at this time; Step 5: Read the reading P3 from the second pressure gauge; input the data into the measuring instrument. At this point, the nitrogen gas in the airbag satisfies the ideal gas law. (3) In the above formula, m 3. At this point, the mass of nitrogen in the airbag is measured. T 3. To determine the temperature of nitrogen gas inside the airbag, V 3. To determine the volume of nitrogen gas in the airbag, the parameters in the above steps satisfy the following formula: (4) (5) Step six: Operate the measuring instrument to calculate the volume of the punched hole: (6) Preferably, in step five, if the P3 value is stable and greater than the ambient air pressure at the working surface, then the measuring instrument is working normally; if P If the pressure value is stable and equal to the ambient air pressure at the working surface, then the measuring airbag is underinflated. In this case, it is necessary to increase the pressure preset value of the measuring instrument and start the operation again. P If the value is unstable and continues to decrease, the measuring device is leaking and needs to be shut down for maintenance.

[0007] Preferably, the measuring instrument is equipped with a first pressure gauge.

[0008] Preferably, the third port of the tee is connected to a second pressure gauge.

[0009] Preferably, the outside of the first air tube is provided with an air passage protection device.

[0010] Preferably, the gas path protection device is a rigid hollow tube.

[0011] Preferably, the measuring airbag is provided with a sealing layer and a protective layer from the inside out, and a gap is reserved between the sealing layer and the protective layer for expansion allowance.

[0012] Preferably, the sealing layer is made of hydrogenated nitrile rubber, and the protective layer is made of wear-resistant canvas.

[0013] Compared with related technologies, the beneficial effects of the present invention are as follows: I. This invention achieves real-time, high-precision measurement of punching volume. Compared with existing methods such as empirical estimation and weighing calculation, this invention, through multi-data acquisition and intelligent calculation, can effectively overcome errors caused by factors such as differences in coal body parameters and coal powder loss, and control the volume measurement error within 2%. Second, this invention not only improves the scientific nature of gas drainage design and effect evaluation, but also provides reliable data support for the safe and efficient mining of deep coal seams, and has important engineering application value. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the hydraulic perforation volume measuring device for coal mines provided by the present invention.

[0015] In the attached diagram: 1. Storage tank; 2. Air pump; 3. Measuring instrument; 4. First air pipe; 5. Valve; 6. First pressure gauge; 7. Throttling valve; 8. Second pressure gauge; 9. Air circuit protection device; 10. Measuring air bag; 11. Drill hole; 12. Working face; 13. Rock stratum; 14. Coal seam; 15. Hole; 16. Tee; 17. Second air pipe. Detailed Implementation

[0016] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. For ease of description, the terms "upper," "lower," "left," and "right" used below only indicate that they correspond to the upper, lower, left, and right directions in the accompanying drawings and do not limit the structure.

[0017] like Figure 1As shown in this embodiment, a hydraulic perforation volume measuring device for coal mines is provided for measuring the volume of a hole 15 in a coal seam 14, below which are a rock stratum 13 and a working face 12. The device includes a hole 15 in the coal seam 14, a measuring airbag 10 in the hole 15, a storage tank 1, an air pump 2, a measuring instrument 3, a throttle valve 7, and the first interface of a tee 16, all located in the working face 12 and connected sequentially via a second air pipe 17. The rock stratum 13 and the working face 12 are sequentially arranged from the coal seam 14. The second interface of the tee 16 is connected to a first air pipe 4. A borehole 11 is drilled in the coal seam 14 and the rock stratum 13, one end of which communicates with the hole 15. The end of the first air pipe 4 away from the tee 16 extends from the borehole 11 and connects to the measuring airbag 10. The second air pipe 17 is equipped with two valves 5, which are located at the inlet and outlet ends of the air pump 2, respectively.

[0018] The measuring airbag 10 adopts a multi-layer composite structure. The inner sealing layer is made of hydrogenated nitrile rubber, providing excellent airtightness, flexibility, and extensibility, ensuring a tight fit against the irregular cavity walls after inflation. The outer protective layer is made of wear-resistant canvas, directly contacting the rough cavity walls and providing additional wear-resistant and scratch-resistant protection. An expansion allowance gap is reserved between the outer protective layer and the inner sealing layer to ensure the airbag reaches the design size and is not prematurely restricted due to an overly tight outer layer. After inflation, the volume of the measuring airbag 10 should essentially cover the perforated hole 15, leaving only a small space with an edge dimension less than 1cm uncovered. Therefore, the final volume calculation error is small, expected to be less than 2%.

[0019] The measuring instrument 3 is equipped with a first pressure gauge 6. The third port of the three-way valve 16 is connected to a second pressure gauge 8. An air path protection device 9 is provided on the outside of the first air tube 4. The air path protection device 9 is composed of multiple rigid hollow tubes connected end to end, the purpose of which is to ensure that the first air tube 4 and the measuring airbag 10 can reach the punch hole 15.

[0020] This invention also provides a method for measuring the volume of hydraulic perforation in coal mines, comprising the following steps: Step 1: Install the above-mentioned coal mine underground hydraulic perforation volume measuring device in the working face 12, and close the two valves 5 and the throttle valve 7.

[0021] Step two: Set the initial and subsequent preset pressure values ​​for the measuring instrument 3. For example, the initial preset value is 3 MPa, and the subsequent preset value is 1.5 MPa. The purpose of setting the pressure value of the measuring instrument 3 is to ensure that nitrogen gas can completely fill the punched hole 15. If the volume of the target punched hole 15 is larger, the preset pressure value should be higher; generally, the preferred preset value is 2 MPa.

[0022] Step 3: Open air pump 2 and valve 5 to extract high-pressure nitrogen from storage tank 1 into measuring instrument 3. When the pressure in measuring instrument 3 reaches the preset value, close air pump 2 and valve 5, and record the nitrogen pressure P1, volume V1, and temperature T1 in measuring instrument 3. At this time, the nitrogen in measuring instrument 3 satisfies the ideal gas law: (1) In the above formula, V 1 represents the volume of measuring instrument 3. T 1 represents the temperature of measuring instrument 3; R gN Let be the gas constant of nitrogen. m 1 represents the mass of nitrogen gas in measuring instrument 3.

[0023] Step four: Open the throttle valve 7 to allow nitrogen gas from the measuring instrument 3 to enter the measuring gas bladder 10 and expand it, and observe the second pressure gauge 8; when the pressure value reaches the preset value of the measuring instrument 3, close the throttle valve 7, and record the pressure P2, volume V2, and temperature T2 of the nitrogen gas in the measuring instrument 3; at this time, the nitrogen gas in the measuring instrument 3 satisfies the ideal gas law: (2) In the above formula, m 2 represents the mass of nitrogen gas in the measuring instrument 3 at this time.

[0024] Step 5: Read the reading P3 from the second pressure gauge 8; input the data into the measuring instrument 3. At this point, the nitrogen gas in the airbag 10 is measured to satisfy the ideal gas law: (3) In the above formula, m 3. At this point, the mass of nitrogen in airbag 10 is measured. T 3. To determine the temperature of nitrogen gas in airbag 10, V 3. To determine the volume of nitrogen gas in airbag 10, the parameters in the above steps satisfy the following formula: (4) (5) Step 6: Operate measuring instrument 3 to calculate the volume of punch hole 15 as follows: (6) In addition to providing calculated data, the second pressure gauge 8 can also be used to determine the stability of the equipment. When reading the second pressure gauge 8 in step d, if... P If the 3-value is stable and greater than the ambient air pressure at the working surface 12, it indicates that the instrument is working normally; if PIf the pressure value of measuring instrument 3 is stable and equal to the ambient air pressure at working surface 12, it indicates that the measuring airbag 10 is underinflated and has not completely filled the punched hole 15. The pressure preset value of measuring instrument 3 needs to be increased and the operation repeated. P If the value is unstable and continues to decrease, it indicates that the equipment is leaking air and needs to be repaired.

[0025] To achieve ideal pressure relief and drainage effects, it is necessary to control the drilling volume of hydraulic perforations. However, there is currently no suitable method for accurately measuring the volume of hydraulic perforations in underground coal mines. This invention achieves real-time, high-precision measurement of the perforation volume. Compared with existing methods such as empirical estimation and weighing calculation, this invention, through data acquisition and intelligent calculation, can effectively overcome errors caused by factors such as differences in coal body parameters and coal powder loss, controlling the volume measurement error to within 2%. This invention not only improves the scientific nature of gas drainage design and effect evaluation but also provides reliable data support for the safe and efficient mining of deep coal seams, possessing significant engineering application value.

[0026] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method of volumetric determination of hydraulic flushing in a coal mine underground, characterized by, Includes the following steps: Step 1: Install a hydraulic perforation volume measuring device in the working face (12). The hydraulic perforation volume measuring device is used to measure the volume of the holes (15) in the coal seam (14). Below the coal seam (14) are the rock strata (13) and the working face (12). The hydraulic perforation volume measuring device includes a measuring airbag (10) installed in the hole (15), a storage tank (1) installed in the working face (12) and connected in sequence through a second air pipe (17), an air pump (2), a measuring instrument (3), and a throttling device. The valve (7) and the first interface of the tee (16); the second interface of the tee (16) is connected to the first air pipe (4); a borehole (11) is constructed in the coal seam (14) and the rock stratum (13), one end of the borehole (11) is connected to the hole (15), and the end of the first air pipe (4) away from the tee (16) extends from the borehole (11) and is connected to the measuring air bag (10); two valves (5) are provided on the second air pipe (17), and the valves (5) are respectively located at the inlet end and the outlet end of the air pump (2); Keep both valves (5) and the throttle valve (7) closed; Step 2: Set the initial and later preset values ​​of the pressure of the measuring instrument (3); Step three, open the air pump (2) and valve (5), the high pressure nitrogen in the storage tank (1) is extracted to the measuring instrument (3), when the pressure of the measuring instrument (3) reaches the preset value, close the air pump (2) and valve (5), and record the nitrogen pressure value in the measuring instrument (3) P 1, volume V 1 and temperature T 1; at this time, the nitrogen in the measuring instrument (3) satisfies the ideal gas state equation: （1） In the above formula, V 1 represents the volume of the measuring instrument (3). T 1 represents the temperature of the measuring instrument (3); R gN Let be the gas constant of nitrogen. m 1 represents the mass of nitrogen gas in the measuring instrument (3); Step four: Open the throttle valve (7) to allow nitrogen gas in the measuring instrument (3) to enter the measuring gas bag (10) and expand it, and observe the second pressure gauge (8); when the pressure value reaches the preset value of the measuring instrument (3), close the throttle valve (7) and record the pressure of nitrogen gas in the measuring instrument (3). P 2. Volume V 2 and temperature T 2; At this time, the nitrogen gas in the measuring instrument (3) satisfies the ideal gas law: （2） In the above formula, m 2 represents the mass of nitrogen in the measuring instrument (3) at this time; Step 5: Read the reading of the second pressure gauge (8). P 3; Input the measuring instrument (3), at this time the nitrogen in the gasbag (10) satisfies the ideal gas law: （3） In the above formula, m 3. At this point, the mass of nitrogen in the airbag (10) is measured. T 3. To determine the temperature of nitrogen gas in the airbag (10), V 3. To determine the volume of nitrogen in the airbag (10), the parameters in the above steps satisfy the following formula: （4） （5） Step 6: Operate the measuring instrument (3) to calculate the volume of the punched hole (15): （6）。 2. The method for determining the volume of hydraulic perforation in underground coal mines according to claim 1, characterized in that, In step five, if P If the value of 3 is stable and greater than the ambient air pressure at the working surface, then the measuring instrument (3) is working normally; if P If the pressure value of the measuring instrument (3) is stable and equal to the ambient air pressure of the working surface, then the measuring airbag (10) is not fully inflated. In this case, it is necessary to increase the pressure preset value of the measuring instrument (3) and start the operation again. like P If the value is unstable and continues to decrease, the measuring device is leaking and needs to be shut down for maintenance.

3. The method for determining the volume of hydraulic perforation in underground coal mines according to claim 1, characterized in that, The measuring instrument (3) is equipped with a first pressure gauge (6).

4. The method for determining the volume of hydraulic perforation in coal mines according to claim 1, characterized in that, The third port of the tee (16) is connected to a second pressure gauge (8).

5. The method for determining the volume of hydraulic perforation in coal mines according to claim 1, characterized in that, The first air pipe (4) is provided with an air passage protection device (9) on its exterior.

6. The method for determining the volume of hydraulic perforation in coal mines according to claim 5, characterized in that, The gas path protection device (9) is a rigid hollow tube.

7. The method for determining the volume of hydraulic perforation in coal mines according to claim 1, characterized in that, The measuring airbag (10) is provided with a sealing layer and a protective layer from the inside to the outside, and a gap with expansion allowance is reserved between the sealing layer and the protective layer.

8. The method for determining the volume of hydraulic perforation in coal mines according to claim 7, characterized in that, The sealing layer is made of hydrogenated nitrile rubber, and the protective layer is made of wear-resistant canvas.

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