Coal bed gas pressure measuring device and method

Abstract

The present invention describes a coal seam gas pressure measurement device and method, which tests and obtains the "first adsorption equilibrium pressure" data of multiple coal seam samples through the measurement device, and obtains the "secondary adsorption equilibrium pressure" data of multiple coal seam samples after a fixed time of gas emission; draws a "first-secondary adsorption equilibrium pressure relationship curve" based on the "first" and "secondary" adsorption equilibrium pressure data of the coal seam samples; and then infers the first adsorption equilibrium pressure of the coal seam field samples, that is, the coal seam gas pressure at the sampling location, based on the secondary adsorption equilibrium pressure of the coal seam field samples measured by underground coal mine sampling. This method can quickly obtain relatively accurate coal seam gas pressure data.

Description

Technical Field

[0001] The present invention relates to the field of safe production in coal mines, and in particular to a device and method for measuring coal seam gas pressure. Background Art

[0002] The coal seam gas pressure measurement methods include indirect method and direct method. Among them, the indirect method requires the measurement of coal seam gas content, porosity, adsorption constant, etc., and then calculates according to the Langmuir equation. There are many measurement parameters, long cycle, and large error; according to AQ / T 1047 "Direct measurement method of coal seam gas pressure in underground coal mines", the direct method also requires a long observation time, active pressure measurement takes 5-20 days, and passive pressure measurement takes 20-30 days.

[0003] In order to quickly obtain the required coal seam gas pressure data, there are currently two main methods:

[0004] a. Empirical method

[0005] The empirical method estimates the coal seam gas pressure data based on the gas pressure data in the area near the coal seam, gas outburst conditions and gas geological maps, etc. The estimation results have low accuracy and large errors.

[0006] b. Gas desorption index estimation method

[0007] The gas desorption index estimation method estimates the gas pressure based on the relationship between the equilibrium pressure of gas adsorbed by coal samples and the gas desorption index. The estimation result also has the problem of large errors because the mass of the coal sample collected when measuring the gas desorption index is small, only 10g, and the gas desorption index is not the pressure of the gas contained in the coal sample.

[0008] Therefore, there is an urgent need to explore a device and method that can accurately and quickly measure coal seam gas pressure. Summary of the invention

[0009] In order to solve the above-mentioned existing technical problems, the present invention provides a coal seam gas pressure measuring device and method.

[0010] The technical solution provided by the present invention is as follows:

[0011] A coal seam gas pressure measuring device, characterized in that it comprises a tank body, a spiral steel pipe, a tank cover, an air duct, a pipeline, an air inlet valve, an air outlet valve and a pressure gauge, wherein the tank body is used to quantitatively load a test coal sample, and the tank cover is provided with a through hole; the tank cover is sealed and connected to the tank body, and is provided with a boss extending into the tank body, when a quantitative test coal sample is loaded into the tank body, the end face of the boss contacts and does not squeeze the plane of the test coal sample; the spiral steel pipe is arranged inside the tank body, at least one end of which is open, and the open end is embedded in the through hole, and the spiral steel pipe is provided with a plurality of air holes; the air duct is led out from the through hole of the tank cover and connected to the pipeline, the air inlet valve and the air outlet valve are installed on the pipeline, and are used to control the gas from the air duct through the spiral steel pipe into and out of the tank body; the pressure gauge is installed at the air duct, and is used to measure and display the gas pressure value in the tank body in real time.

[0012] Furthermore, the inner wall of the tank body is provided with a circle of limiting steps.

[0013] Furthermore, the inner side wall of the tank body is provided with an internal thread, and the internal thread is located between the limiting step and the open end surface of the tank body; the outer side wall of the boss is provided with an external thread matching with the internal thread.

[0014] Furthermore, a sealing ring is provided between the tank body and the tank cover.

[0015] Furthermore, a joint is installed at the open end of the spiral steel pipe, and the joint is interference fit with the through hole.

[0016] Furthermore, the joint is made of silicone material or cork.

[0017] A method for measuring coal seam gas pressure, using a coal seam gas pressure measuring device, comprises the following steps:

[0018] S1. Collect coal samples from the coal seam area and use a sieve to sieve out coal samples with a particle size of 1mm-3mm as test coal samples;

[0019] S2. quantitatively load the test coal sample into the tank until its upper surface is flush with the limit step;

[0020] S3. Close the outlet valve, open the inlet valve, fill the tank with gas at a pressure of P1, and then close the inlet valve. When the test coal sample reaches the first adsorption equilibrium state, record the pressure gauge value M1 at this time;

[0021] S4. After opening the outlet valve and maintaining it for a fixed time, close the outlet valve, and when the test coal sample reaches a secondary adsorption equilibrium state, record the pressure gauge value N1 at this time;

[0022] S5. Open the gas outlet valve and leave the measuring device to stand for a period of time until the test coal sample returns to its initial state;

[0023] S6. Change the pressure in step 3 to P2, and repeat steps 3 to 5.

[0024] Record the pressure gauge value M2 when the test coal sample reaches the first adsorption equilibrium state;

[0025] Record the pressure gauge value N2 when the test coal sample reaches the secondary adsorption equilibrium state;

[0026] S7. Repeat step 6 several times and change the gas pressure in step 3 to obtain:

[0027] A set of pressure gauge values ​​M1 when the test coal sample reaches the first adsorption equilibrium state... i ………M x ,

[0028] A set of pressure gauge values ​​N1………N when the test coal sample reaches the secondary adsorption equilibrium state i ………N x ;

[0029] S8. With the value M1………M i ………M x As the horizontal axis, the value N1………N i ………N x As the ordinate, draw the “first-second adsorption equilibrium pressure relationship curve”;

[0030] S9. Collect coal seam field samples in the area where the coal seam is located, and complete the screening and sampling of the coal seam field samples and load them into the tank within the fixed time described in step S4, close the air inlet valve and the air outlet valve, and when the coal seam field samples reach the secondary adsorption equilibrium state, record the pressure gauge value N at this time 实 ;

[0031] S10. According to the "first-second adsorption equilibrium pressure relationship curve", obtain the corresponding N 实 The first adsorption equilibrium pressure M of the coal seam field sample 实 , the M 实 This is the estimated value of the coal seam gas pressure in the area where the coal seam is located.

[0032] Furthermore, the fixed time in step S4 is 3 minutes.

[0033] Beneficial effects of the present invention:

[0034] 1. The coal seam gas pressure measuring device and method described in the present invention can accurately measure the values ​​of the first adsorption equilibrium pressure and the second adsorption equilibrium pressure of the coal sample. By establishing a first-second adsorption equilibrium pressure relationship curve, relatively accurate coal seam gas pressure data can be quickly obtained.

[0035] 2. The coal seam gas pressure measuring device described in the present invention has a limit step arranged in the tank body, which can limit the number of coal samples tested each time. When the coal samples are loaded to this position, the tank cover is tightened, and the boss end face of the tank cover just contacts with the coal samples, which neither compresses the coal samples nor leaves extra space, thereby ensuring the consistency of each experiment.

[0036] 3. The coal seam gas pressure measuring device described in the present invention has a spiral steel pipe with air holes built into the tank body. The injected gas can quickly contact the coal sample through the air holes on the spiral steel pipe without gradually penetrating downward from the upper part of the coal sample. This can not only increase the adsorption speed, but also improve the balance of gas adsorption by the entire coal sample. Similarly, when discharging the coal sample gas in the tank body, the discharge rate and balance can also be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 : A schematic diagram of the structure of the coal seam gas pressure measuring device of the present invention;

[0038] Figure 2 : First-second adsorption equilibrium pressure relationship curve.

[0039] Explanation of symbols

[0040] 1-tank body, 11-limiting step, 12-internal thread;

[0041] 2- spiral steel pipe, 21- joint, 22- air hole;

[0042] 3-tank cover, 31-base, 32-boss, 33-through hole, 34-external thread;

[0043] 4-air guide pipe, 5-pipeline, 6-inlet valve, 7-outlet valve, 8-pressure gauge, 9-sealing ring. DETAILED DESCRIPTION

[0044] The present invention will be described in detail below by way of embodiments in conjunction with the accompanying drawings.

[0045] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in components' functions as the criterion for distinction.

[0046] like Figure 1 As shown, a coal seam gas pressure measuring device includes a tank body 1, a spiral steel pipe 2, a tank cover 3, an air guide pipe 4, a pipeline 5, an air inlet valve 6, an air outlet valve 7 and a pressure gauge 8.

[0047] The tank body 1 is a regular barrel-shaped structure with one end open. A circle of limiting steps 11 is arranged on the inner side wall of the tank body 1, and the limiting steps 11 are arranged near the open end of the tank body 1.

[0048] The inner wall of the tank body 1 is provided with an internal thread 12 , and the internal thread 12 is arranged between the upper surface of the limiting step 11 and the open end surface of the tank body 1 .

[0049] The tank cover 3 comprises a base 31 and a boss 32 , and a through hole 33 is formed along the central axis of the tank cover 3 .

[0050] The base 31 is circular, and its outer diameter is slightly larger than the outer diameter of the tank body 1 .

[0051] The boss 32 is located at the center of the base 31, protruding toward the tank body and having a certain height. The outer wall of the boss 32 is provided with an outer thread 34 that matches the inner thread 12 of the tank body. When the tank cover 3 is threadedly connected to the tank body 1 and tightened, the upper surface of the boss 32 contacts the upper surface of the limiting step 11. In order to ensure the airtightness between the tank body 1 and the tank cover 3, a sealing ring 9 is provided between the tank body 1 and the tank cover 3.

[0052] The spiral steel pipe 2 is arranged inside the tank body 1, and at least one end thereof is open, and a joint 21 is installed at the open end. The joint 21 is embedded in the through hole 33 of the tank cover 3 and has an interference fit with the through hole 33. To ensure air tightness, the joint 21 is made of silicone material or cork.

[0053] The surface of the spiral steel pipe 2 is distributed with pores 22, and the density of the pores 22 should be adjusted accordingly according to the actual needs of the test; the diameter of the pores 22 of the spiral steel pipe 2 is less than 1 mm to prevent coal samples from entering and exiting.

[0054] The air guide pipe 4 is led out from the through hole 33 of the tank cover 3 and connected to the pipeline 5 in a T-shape; the air inlet valve 6 and the air outlet valve 7 are installed on the pipeline 5 and distributed on both sides of the air guide pipe 4.

[0055] The pressure gauge 8 is installed at the air duct 4 and is used to measure and display the gas pressure value in the tank body 1 in real time.

[0056] Using the above-mentioned coal seam gas pressure measuring device, this embodiment provides a coal seam gas pressure measuring method, including the following steps:

[0057] 1. Collect coal samples from the coal seam area where gas pressure measurement is required, and use a sieve to screen out coal samples with a particle size of 1mm-3mm as test coal samples.

[0058] 2. Load the test coal sample into the tank of the measuring device and complete the installation of the measuring device, which should meet the following requirements:

[0059] a. The loading amount of the test coal sample is: when the test coal sample is fully loaded into the tank, its upper surface is flush with the limit step;

[0060] b. Tighten the tank cover so that the end face of the tank cover boss naturally contacts the upper plane of the test coal sample.

[0061] In this step, when the test coal sample is loaded into the tank, the tank should be gently shaken, or the tank should be tapped to ensure that the test coal sample fully fills the tank space.

[0062] 3. Close the outlet valve, open the inlet valve, fill the tank with gas at pressure P1, and then close the inlet valve;

[0063] Observe the pressure gauge value in real time. When the pressure gauge value no longer changes, the test coal sample reaches the first adsorption equilibrium state. Record the pressure gauge value M1 at this time.

[0064] 4. Open the air outlet valve and keep it open for 3 minutes before closing it;

[0065] Observe the pressure gauge value in real time. When the pressure gauge value no longer changes, the test coal sample reaches the secondary adsorption equilibrium state. Record the pressure gauge value N1 at this time.

[0066] 5. Open the gas outlet valve and let the device stand for a period of time until the test coal sample returns to its initial state.

[0067] 6. Change the pressure in step 3 to P2, and repeat steps 3 to 5.

[0068] Record the pressure gauge value M2 when the test coal sample reaches the first adsorption equilibrium state;

[0069] Record the pressure gauge value N2 when the test coal sample reaches the secondary adsorption equilibrium state.

[0070] 7. Repeat step 6 several times and change the gas pressure in step 3 to obtain:

[0071] When the test coal sample reaches the first adsorption equilibrium state, a set of pressure gauge values ​​M1………M i ………M x ;

[0072] When the test coal sample reaches the secondary adsorption equilibrium state, a set of pressure gauge values ​​N1………N i ………N x .

[0073] 8. As Figure 2 As shown, with the value M1…M i ………Mx As the horizontal axis, with the value N1………N i ………N x As the vertical axis, draw the “first-second adsorption equilibrium pressure relationship curve”.

[0074] 9. Collect coal seam field samples in the coal seam area, complete the screening and sampling of coal seam field samples and load them into the tank within 3 minutes, close the air inlet valve and air outlet valve of the device, and observe the pressure gauge value in real time. When the pressure gauge value no longer changes, the coal seam field sample reaches the secondary adsorption equilibrium state, and record the pressure gauge value N at this time. 实 .

[0075] 10.According to the “first-second adsorption equilibrium pressure relationship curve”, obtain the corresponding N 实 The first adsorption equilibrium pressure M of the coal seam field sample 实 , M 实 This is the estimated value of the coal seam gas pressure in the area where the coal seam is located.

[0076] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A method for measuring coal seam gas pressure, characterized in that: Including tank body, spiral steel pipe, tank cover, air guide pipe, pipeline, air inlet valve, air outlet valve and pressure gauge, in, The tank body is used to quantitatively load the test coal sample, the tank cover is provided with a through hole, and the inner wall of the tank body is provided with a circle of limiting steps; The tank cover is sealedly connected to the tank body and is provided with a boss extending into the tank body. When a certain amount of the test coal sample is loaded into the tank body, the end surface of the boss contacts the plane of the test coal sample without squeezing it. The spiral steel pipe is arranged inside the tank body, at least one end of which is open, the open end is embedded in the through hole, and the spiral steel pipe is provided with a plurality of air holes; The air guide pipe is led out from the through hole of the tank cover and connected to the pipeline. The air inlet valve and the air outlet valve are installed on the pipeline to control the gas from the air guide pipe to enter and exit the tank through the spiral steel pipe. The pressure gauge is installed at the air duct and is used to measure and display the gas pressure value in the tank in real time; S1. Collect coal samples from the coal seam area and use a sieve to sieve out coal samples with a particle size of 1mm-3mm as test coal samples; S2. quantitatively load the test coal sample into the tank until its upper surface is flush with the limit step; S3. Close the outlet valve, open the inlet valve, fill the tank with gas at a pressure of P1, and then close the inlet valve. When the test coal sample reaches the first adsorption equilibrium state, record the pressure gauge value M1 at this time; S4. After opening the outlet valve and maintaining it for a fixed time, close the outlet valve, and when the test coal sample reaches a secondary adsorption equilibrium state, record the pressure gauge value N1 at this time; S5. Open the gas outlet valve and leave the measuring device to stand for a period of time until the test coal sample returns to its initial state; S6. Change the pressure in step 3 to P2, and repeat steps 3 to 5. Record the pressure gauge value M2 when the test coal sample reaches the first adsorption equilibrium state; Record the pressure gauge value N2 when the test coal sample reaches the secondary adsorption equilibrium state; S7. Repeat step 6 several times and change the gas pressure in step 3 to obtain: A set of pressure gauge values ​​M1 when the test coal sample reaches the first adsorption equilibrium state... i ………M x , A set of pressure gauge values ​​N1………N when the test coal sample reaches the secondary adsorption equilibrium state i ………N x ; S8. With the value M1………M i ………M x As the horizontal axis, the value N1………N i ………N x As the ordinate, draw the "first-second adsorption equilibrium pressure relationship curve"; S9. Collect coal seam field samples in the area where the coal seam is located, and complete the screening and sampling of the coal seam field samples and load them into the tank within the fixed time described in step S4, close the air inlet valve and the air outlet valve, and when the coal seam field samples reach the secondary adsorption equilibrium state, record the pressure gauge value N at this time 实 ; S10. According to the "first-second adsorption equilibrium pressure relationship curve", obtain the corresponding N 实 The first adsorption equilibrium pressure M of the coal seam field sample 实 , the M 实 This is the estimated value of the coal seam gas pressure in the area where the coal seam is located.

2. A method for calculating coal seam gas pressure according to claim 1, characterized in that: The inner wall of the tank body is provided with an internal thread, and the internal thread is located between the limiting step and the open end surface of the tank body; the outer wall of the boss is provided with an external thread matching the internal thread.

3. A method for calculating coal seam gas pressure according to claim 2, characterized in that: A sealing ring is arranged between the tank body and the tank cover.

4. A method for measuring coal seam gas pressure according to any one of claims 1 to 3, characterized in that: A joint is installed at the open end of the spiral steel pipe, and the joint is interference fit with the through hole.

5. A method for calculating coal seam gas pressure according to claim 4, characterized in that: The joint is made of silicone material or cork.

6. A method for calculating coal seam gas pressure according to claim 4, characterized in that: The diameter of the pores of the spiral steel pipe is smaller than the particle size of the test coal sample.

7. A method for calculating coal seam gas pressure according to claim 1, characterized in that: The fixing time in step S4 is 3 minutes.

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