Coal seam gas content testing device with drying function and testing method

Abstract

The invention relates to the technical field of coal mine safety, in particular to a coal seam gas content testing device with a drying function and a testing method. According to the testing device, a spin-drying barrel is rotatably arranged in a device shell, a spin-drying system used for supporting and driving the spin-drying barrel to rotate and a crushing system used for crushing a coal sample in the spin-drying barrel are arranged in the device shell, a nylon brush sliding rail is fixedly arranged on the inner wall of the device shell, and a nylon brush is detachably arranged on the nylon brush sliding rail; the data acquisition system is used for acquiring the total flow of gas desorbed from the coal sample, the concentration of methane in the gas and the temperature and the air pressure of the external environment of the testing device, and the data processing system is used for processing data acquired by the data acquisition system to obtain the gas content of the coal seam. The situation that the desorption rule of gas is changed due to high-temperature drying of the high-water-content coal sample can be avoided, the application range of the testing device is widened, and the testing accuracy is improved.

Description

Technical Field

[0001] This invention relates to the field of coal mine safety technology, and in particular to a coal seam gas content testing device and method with a drying function. Background Technology

[0002] my country's coal resources are characterized by complex geological conditions, with most coal seams having high methane content, making them susceptible to gas hazard threats during mining. Against this backdrop, rapid and accurate testing of coal seam methane content is crucial. It serves not only as the basis for predicting mine gas emission and calculating coalbed methane reserves, but also as a primary foundation for designing mine ventilation and gas extraction systems and evaluating the risk of coal seam outbursts.

[0003] When testing the gas content of a coal seam, the coal sample first needs to be crushed, and then the amount of gas desorption from the crushed coal sample is measured using a flow sensor to calculate the gas content of the coal seam.

[0004] However, for high-gas coal seams, due to their poor permeability, permeability enhancement techniques such as hydraulic fracturing and hydraulic slotting are often used, resulting in a significant increase in the moisture content of coal samples from high-gas coal seams. When crushing such high-moisture coal samples, the particles mix with water vapor during the crushing process, causing sticking, adhesion, or agglomeration, which affects the crushing effect and makes it difficult to effectively crush them to the particle size required for gas content testing. Directly drying them by high-temperature heating will change the gas desorption pattern of the coal sample, thus affecting the accuracy of gas content testing. Summary of the Invention

[0005] Based on the above-mentioned technical problems, the present invention aims to provide a coal seam gas content testing device and its testing method with drying function, so as to solve the technical problems that high temperature drying will change the desorption law of gas and the crushing particle size will not meet the testing requirements when testing the gas content of high moisture content filter coal samples, and the crushing process is prone to sticking, sticking or agglomeration, thereby improving the applicability and accuracy of gas content determination in high gas coal seams.

[0006] To achieve the above objectives, the present invention provides a coal seam gas content testing device with a drying function, comprising: a device shell and a baffle fixedly disposed within the device shell; a spin-drying cylinder rotatably disposed within the device shell, the axis of the spin-drying cylinder being horizontally arranged and located on the other side of the baffle; a spin-drying system for supporting and driving the rotation of the spin-drying cylinder and a crushing system for crushing the coal sample within the spin-drying cylinder provided within the device shell; a sealing cover plate for sealing the open end of the spin-drying cylinder provided on the outer wall of the device shell; and openings respectively on the outer wall of the device shell for connecting to the spin-drying cylinder. The device includes a drainage pipe and an exhaust pipe connected to the internal space of the outer shell of the drying cylinder. The drainage pipe is equipped with a drainage valve, and the exhaust pipe is equipped with an exhaust valve. A nylon brush slide rail is fixedly installed on the inner wall of the outer shell of the device, located between the outer shell and the drying cylinder. A nylon brush is detachably installed on the nylon brush slide rail. The device also includes: a data acquisition system for collecting the total flow rate of the gas desorbed from the coal sample and the concentration of methane in the gas, and for collecting the temperature and air pressure of the external environment of the testing device; and a data processing system for processing the data collected by the data acquisition system to obtain the gas content of the coal seam.

[0007] Furthermore, the spin-drying system includes: a rotating shaft and a first motor, the first motor being connected to the rotating shaft via a belt drive mechanism; one end of the rotating shaft is rotatably connected to the closed end of the spin-drying cylinder after passing through a baffle, the rotating shaft and the spin-drying cylinder are coaxially arranged, the other end of the rotating shaft is rotatably arranged in the rotating shaft base, and the rotating shaft base is fixedly connected to the inner wall of the device housing;

[0008] Furthermore, a first mechanical rotary seal is provided at the mating point between the rotating shaft and the baffle;

[0009] Furthermore, the crushing system includes a rotating rod, which is coaxially arranged with the rotating shaft. One end of the rotating rod is connected to the second output shaft of the second motor. The other end of the rotating rod passes through the rotating shaft base, the rotating shaft and the closed end of the spin-drying cylinder in sequence and is then disposed inside the spin-drying cylinder. Multiple crushing blades are fixedly connected to the rotating rod on the outer wall inside the spin-drying cylinder.

[0010] Furthermore, the rotating rod is a telescopic rod, and the second motor is a dual-servo telescopic rotary electric cylinder;

[0011] Furthermore, a second mechanical rotary seal is provided at the mating point between the rotating rod and the spin dryer;

[0012] Furthermore, a plastic sleeve is provided between the outer shell of the device and the spin-drying cylinder, and the outer wall of the plastic sleeve is fixedly connected to the inner wall of the outer shell of the device by multiple suspension springs.

[0013] Furthermore, the data acquisition system includes: an electronic flow sensor and a methane concentration sensor located inside the exhaust pipe; it also includes a temperature sensor and an atmospheric pressure sensor for detecting the ambient temperature and air pressure of the entire test device, respectively.

[0014] Furthermore, multiple support feet are fixedly provided on the outer wall of the device housing.

[0015] On the other hand, the present invention also provides a method for testing coal seam gas content using the above-mentioned coal seam gas content testing device, comprising the following:

[0016] First, place the coal sample into the drying cylinder and seal it by closing the sealing cover, drain valve, and exhaust valve;

[0017] Then, the coal sample is spun dry, dried and crushed using a spun dry system and a crushing system. After the spun dry system and crushing system have finished working, they are turned off and left to stand for 3 minutes.

[0018] Finally, the exhaust valve was opened, and the total flow rate of the gas desorbed from the coal sample in the exhaust pipe and the concentration of methane in the gas, as well as the temperature and pressure of the external environment of the test device, were collected using the data acquisition system and uploaded to the data acquisition system.

[0019] The data processing system uses a data acquisition system to collect data and calculates the gas content of the coal seam. The specific process is as follows:

[0020] Calculate the flow rate of methane in the gas desorbed from the coal sample in the exhaust pipe (21). It satisfies the following formula:

[0021] ;

[0022] In the formula: q represents the flow rate of methane in the desorbed gas from the coal sample; q represents the total flow rate of the desorbed gas from the coal sample; and c represents the concentration of methane in the desorbed gas from the coal sample.

[0023] According to the gas flow equation, the flow rate of methane in the gas desorbed from the coal sample in the exhaust pipe (21) is calculated. Converted to the flow rate of methane under the external atmospheric pressure conditions of the testing device It satisfies the following formula:

[0024] ;

[0025] In the formula: P is the external ambient air pressure of the test device; W is the external ambient temperature of the test device;

[0026] Then, the flow rate of methane was measured under the external ambient pressure conditions of the testing device. The coal seam gas content Q is calculated according to the following formula:

[0027] ;

[0028] In the formula: Q is the gas content of the coal seam; T is the cumulative test time; M is the mass of the coal sample.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] The coal seam gas content testing device with drying function provided by this invention dries high-moisture coal samples using a rotating spin-drying drum, avoiding changes in the desorption behavior of gas due to high-temperature drying, thus expanding the application range of the testing device. Simultaneously, the internal nylon brush automatically cleans the sieve holes of the spin-drying drum, preventing them from being blocked by broken coal samples and affecting the discharge of desorbed gas. Furthermore, during testing, the use of corresponding sensors to detect the amount of methane desorbed in the desorbed gas improves the accuracy of the coal seam gas content test. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure of a coal seam gas content testing device with drying function according to the present invention.

[0032] Figure 2 This is a schematic diagram of the spin-drying system of the present invention;

[0033] Figure 3 This is a schematic diagram of the crushing system of the present invention;

[0034] Figure 4 This is a partially enlarged view of the drying system and crushing system of the present invention;

[0035] Figure 5 This is a schematic diagram of the installation structure of the nylon brush of the present invention;

[0036] In the diagram: 1. Device housing; 2. Baffle; 3. First mechanical rotary seal; 4. Shaft base; 5. Shaft; 6. Second mechanical rotary seal; 7. Second motor; 9. Synchronous belt; 10. First output shaft; 11. First motor; 16. Rotating rod; 17. Nylon brush slide rail; 18. Nylon brush; 19. Crushing blade; 20. Gas drying device; 21. Exhaust pipe; 22. Exhaust valve; 23. Electronic flow sensor; 24. Methane concentration sensor; 28. Exhaust port; 29. ​​Sealing cover; 30. Plastic sleeve; 31. Suspension spring; 32. Support foot; 33. Drainage pipe; 34. Drainage valve; 35. Spin-drying drum. Detailed Implementation

[0037] The technical solution adopted in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] First, such as Figure 1 As shown, this invention provides a coal seam gas content testing device with a drying function, comprising: a device shell 1, a drying system, a crushing system, a data acquisition system, and a data processing system, wherein:

[0039] Multiple support feet 32 ​​are fixedly installed on the outer wall of the device housing 1. The support feet 32 ​​are used to fix the device to the ground foundation to ensure the stability of the entire testing device. A baffle 2 is fixedly installed inside the device housing 1. The baffle 2 divides the internal space of the device housing 1 into two independent spaces, left and right. A spin-drying cylinder 35 is rotatably installed inside the device housing 1 in one of the spaces. The spin-drying cylinder 35 is a cylindrical structure with one end open, and the axis of the spin-drying cylinder 35 is parallel to the ground. The spin-drying cylinder 35 is used to store coal samples. At the same time, multiple through holes with a diameter ≤0.1mm are opened on the cylinder wall of the spin-drying cylinder 35. By driving the spin-drying cylinder 35 to rotate around its axis, the coal sample inside can be rotated, thereby achieving the spin-drying and dehydration of the coal sample to obtain a dried coal sample.

[0040] Located at the end where the device housing 1 and the spin dryer 35 share an opening, a sealing cover 29 for sealing the spin dryer 35 is provided on the outer wall of the device housing 1. One end of the sealing cover 29 can be rotatably fixed to the outer wall of the device housing 1 by hinge, and the other end can be fixed to the outer wall of the device housing 1 by snap-fit, thereby achieving the sealing of the device housing 1 and the opening end of the spin dryer 35 by the sealing cover 29. The sealing cover 29 can be opened on the device housing 1 to quickly put the fresh coal sample into the spin dryer 35, and then the sealing cover 29 can be closed to keep the coal sample in the spin dryer 35 in a relatively sealed state.

[0041] Meanwhile, a drainage pipe 33 is also provided on the outer wall of the device housing 1, which is connected to the internal space of the device housing 1 where the spin dryer 35 is located. The drainage pipe 33 is preferably located at the bottom of the device housing 1. A drainage valve 34 is provided in the drainage pipe 33, which can connect the drainage pipe 33 to the external suction equipment. When the drainage valve 34 is opened, the water discharged during the spin dryer and dewatering of the coal sample is extracted by the external suction equipment.

[0042] Located in another space of the device housing 1, there is a spin-drying system for supporting and driving the spin-drying drum 35 to rotate, and a crushing system for crushing the coal sample inside the spin-drying drum 35.

[0043] like Figure 2As shown, the spin-drying system includes: a rotating shaft 5 and a rotary drive mechanism for driving the rotating shaft 5 to rotate. One end of the rotating shaft 5 is rotatably connected to the closed end of the spin-drying cylinder 35 after passing through the baffle 2, while ensuring that the rotating shaft 5 and the spin-drying cylinder 35 are coaxially arranged. A first mechanical rotation seal 3 is provided at the connection between the rotating shaft 5 and the baffle 2, that is, the first mechanical rotation seal 3 ensures that the rotating shaft 5 can rotate inside the baffle 2 and prevents gas and moisture from leaking into the space.

[0044] The other end of the rotating shaft 5 is rotatably disposed in the rotating shaft base 4. Specifically, the end of the rotating shaft 5 can be set in a "T" shape and embedded in the rotating shaft base 4 to achieve that the end of the rotating shaft 5 is rotatably disposed in the rotating shaft base 4. The gap between the two is filled with lubricating oil, and the rotating shaft base 4 is fixedly connected to the inner wall of the device housing 1.

[0045] A rotary drive mechanism is provided, which can be set inside the housing 1 of the device and fixedly connected to the inner wall of the housing 1. It includes a first motor 11 and a belt drive mechanism. Specifically, the rotating shaft 5 is connected to the first output shaft 10 of the first motor 11 by a synchronous belt 9. By controlling the rotation of the first output shaft 10 of the first motor 11, the rotating shaft 5 can be driven to rotate by the synchronous belt 9, and then the rotating shaft 5 can drive the spin-drying cylinder 35 to rotate, thereby realizing the spin-drying and dehydration of the coal sample in the spin-drying cylinder 35.

[0046] Furthermore, a plastic sleeve 30 is provided between the device housing 1 and the spin-drying cylinder 35, which is fitted over the outside of the spin-drying cylinder 35. The outer wall of the plastic sleeve 30 is connected and fixed to the inner wall of the device housing 1 by multiple suspension springs 31, so that the plastic sleeve 30 is fixed to the outside of the spin-drying cylinder 35 with a gap of about 3mm. This is used to prevent the spin-drying cylinder 35 from swinging too much during rotation and to extend the service life of the device.

[0047] like Figure 3 and Figure 4 As shown, the crushing system includes: a rotating rod 16, crushing blades 19, and a second motor 7 for driving the rotating rod 16 to rotate;

[0048] The rotating rod 16 is coaxially arranged with the rotating shaft 5. One end of the rotating rod 16 is connected to the second output shaft of the second motor 7. The other end of the rotating rod 16 is rotated through the rotating shaft base 4, the rotating shaft 5 and the closed end of the spin dryer 35 and is then placed inside the spin dryer 35. At the same time, multiple crushing blades 19 are fixedly connected to the outer wall of the rotating rod 16 inside the spin dryer 35. That is, the second motor 7 drives the multiple crushing blades 19 to rotate inside the spin dryer 35 via the rotating rod 16 to crush the coal sample inside the spin dryer 35, so that the gas in the coal can be quickly desorbed after dehydration.

[0049] Furthermore, the joint between the telescopic rotating rod 16 and the spin dryer 35 is sealed at the joint by the second mechanical rotating seal 6 to prevent gas and moisture leakage. All openings in the outer casing 1 of the device are sealed to prevent moisture and gas from leaking to the outside of the device during operation and affecting the detection accuracy.

[0050] Preferably, in order to improve the crushing effect of the crushing system, in this embodiment, the rotating rod 16 can be a telescopic rod, that is, the fixed end of the rotating rod 16 is connected to the second motor 7 for transmission, and the telescopic end of the rotating rod 16 is set inside the spin dryer 35. At this time, the second motor 7 is a dual servo telescopic rotary electric cylinder, that is, the rotating rod 16 is driven to rotate and telescopic through the dual servo telescopic rotary electric cylinder, thereby driving multiple crushing blades 19 to rotate and telescopic, thereby improving the crushing effect on the coal sample inside the spin dryer 35;

[0051] Furthermore, such as Figure 5 As shown, a nylon brush slide rail 17 is fixedly installed on the inner wall of the device housing 1 between the device housing 1 and the spin dryer 35. A nylon brush 18 is detachably provided on the nylon brush slide rail 17. If the nylon brush 18 is inserted into the nylon brush slide rail 17, the bristles of the nylon brush 18 will clean the through holes of the spin dryer 35 in sequence during the rotation of the spin dryer 35, so as to prevent the broken coal powder from clogging the through holes on the body of the spin dryer 35.

[0052] An exhaust pipe 21 is also provided on the outer casing 1 of the device. An exhaust valve 22 is provided inside the exhaust pipe 21. A gas drying device 20 is provided at the connection between the exhaust pipe 21 and the outer casing 1 of the device. The end of the exhaust pipe 21 away from the outer casing 1 of the device is an exhaust port 28. The exhaust port 28 can be connected to a gas purification treatment device.

[0053] The data acquisition system is used to collect the total flow rate of the gas desorbed from the crushed coal sample and the concentration of methane in the gas, as well as the temperature and standard pressure of the external environment of the testing device. It includes an electronic flow sensor 23 and a methane concentration sensor 24 located in the exhaust pipe 21.

[0054] The data acquisition system also includes a temperature sensor and an atmospheric pressure sensor for acquiring the ambient temperature and air pressure of the entire test device, respectively.

[0055] The data processing system is used to process the data collected by the data acquisition system, that is, to calculate the gas content of the coal seam by using the gas desorption amount of the crushed coal sample through the gas flow equation.

[0056] Secondly, based on the above-mentioned testing device, the present invention also provides a method for testing coal seam gas content, comprising the following:

[0057] S1: Place the coal sample into the drying cylinder 35, and then seal it with the sealing cover 29, the exhaust valve 22 and the drain valve 34.

[0058] S2: Using the spin-drying system and crushing system of the testing device, the coal sample is spin-dryed, dried and crushed to allow the gas inside the coal sample to be released more completely, i.e. desorbed. The time for both spin-drying and crushing is not less than 3 minutes.

[0059] S3: After the drying and crushing systems have finished working, shut them off and let them stand for 3 minutes. Then open the exhaust valve 22 and use the electronic flow sensor 23 and the methane concentration sensor 24 to collect the total flow rate of the gas desorbed from the coal sample in the exhaust pipe 21 and the methane concentration in the gas. Use the temperature sensor 26 and the atmospheric pressure sensor 27 to collect the ambient temperature and air pressure data of the test device, and upload them to the data processing system for storage. The data processing system processes the above data and obtains the gas content of the coal seam.

[0060] When collecting coal sample gas desorption data, it is necessary to record continuously for half an hour or the desorption rate must be less than 2 ml / min.

[0061] Furthermore, the data processing system uses the data collected by the data acquisition system to calculate the gas content of the coal seam. The specific process is as follows:

[0062] The flow rate of methane in the gas desorbed from the coal sample satisfies the following equation:

[0063] (1);

[0064] In formula (1): The flow rate of methane in the gas desorbed from the coal sample is expressed in m³ / s. 3 / h (cubic meters per hour); q is the total flow rate of gas desorbed from the coal sample, in m³ / h. 3 / h (cubic meters per hour) can be obtained through electronic flow sensor 23; c is the concentration of methane in the desorbed gas of the coal sample, which can be obtained through methane concentration sensor 24;

[0065] Based on the gas flow equation, the flow rate of methane in the desorbed gas from the coal sample is calculated. Converted to the flow rate of methane under the external atmospheric pressure conditions of the testing device It satisfies the following formula:

[0066] (2);

[0067] In formula (2): P is the external ambient air pressure of the test device, in kPa (kilopascals), which can be obtained by an atmospheric pressure sensor; W is the external ambient temperature of the test device, in ℃ (degrees Celsius), which can be obtained by a temperature sensor.

[0068] Then, the methane flow rate under the external ambient pressure conditions of the test device was measured. The coal seam gas content Q is calculated according to the following formula:

[0069] (3);

[0070] In formula (3): Q is the gas content of the coal seam, in m³. 3 / t (cubic meters per ton); T is the cumulative testing time in hours (h); M is the mass of the coal sample in tons (t).

[0071] After the test is completed, open the drain valve 34 to drain the water and then close it. Before the next test, remove any residual coal sample from the device and dry the inside of the device to prevent residual coal sample and moisture from the previous test from affecting the test accuracy.

Claims

1. A coal seam gas content testing device with drying function, characterized in that, It includes: The device shell (1) and the baffle (2) fixedly arranged in the device shell (1), one side of the baffle (2) is rotatably provided with a spin-drying cylinder (35) in the device shell (1), the axis of the spin-drying cylinder (35) is horizontally arranged, the other side of the baffle (2) is provided with a spin-drying system for supporting and driving the spin-drying cylinder (35) to rotate and a crushing system for crushing the coal sample in the spin-drying cylinder (35) in the device shell (1); The outer wall of the device shell (1) is provided with a sealing cover plate (29) for sealing the opening end of the spin-drying cylinder (35); The outer wall of the device shell (1) is respectively provided with a drainage pipeline (33) and an exhaust pipe (21) which are communicated with the internal space of the device shell (1) where the spin-drying cylinder (35) is located, the drainage pipeline (33) is provided with a drainage valve (34), and the exhaust pipe (21) is provided with an exhaust valve (22); The nylon brush sliding rail (17) is fixedly arranged on the inner wall of the device shell (1) between the device shell (1) and the spin-drying cylinder (35), and the nylon brush (18) is detachably arranged on the nylon brush sliding rail (17); It also includes a data acquisition system for collecting the total flow of the desorbed gas of the coal sample and the concentration of methane in the gas and the temperature and air pressure of the external environment of the test device, and a data processing system for processing the data collected by the data acquisition system to obtain the gas content of the coal seam.

2. The coal-bed gas content testing device with drying function according to claim 1, characterized in that, The spin-drying system includes a rotating shaft (5) and a first motor (11), and the first motor (11) is in transmission connection with the rotating shaft (5) through a belt transmission mechanism. One end of the rotating shaft (5) is rotatably penetrated through the baffle (2) and fixedly connected with the closed end of the spin-drying cylinder (35), and the rotating shaft (5) is coaxially arranged with the spin-drying cylinder (35). The other end of the rotating shaft (5) is rotatably arranged in the rotating shaft base (4), and the rotating shaft base (4) is fixedly connected to the inner wall of the device shell (1).

3. The coal-bed gas content testing device with drying function according to claim 2, characterized in that, A first mechanical rotary sealing member (3) is arranged at the cooperation position of the rotating shaft (5) and the baffle (2).

4. The coal-bed gas content testing device with drying function according to claim 1, characterized in that, The crushing system includes a rotating rod (16), the rotating rod (16) is coaxially arranged with the rotating shaft (5), one end of the rotating rod (16) is in transmission connection with the second output shaft of the second motor (7), the other end of the rotating rod (16) is sequentially rotatably penetrated through the rotating shaft base (4), the rotating shaft (5) and the closed end of the spin-drying cylinder (35) and then arranged in the interior of the spin-drying cylinder (35), and a plurality of crushing blades (19) are fixedly connected to the outer wall of the rotating rod (16) in the spin-drying cylinder (35).

5. The coal-bed gas content testing device with drying function according to claim 4, characterized in that, The rotating rod (16) is a telescopic rod, and the second motor (7) is a double-servo telescopic rotary electric cylinder.

6. The coal-bed gas content testing device with drying function according to claim 5, characterized in that, A second mechanical rotary sealing member (6) is arranged at the cooperation position of the rotating rod (16) and the spin-drying cylinder (35).

7. The coal-bed gas content testing device with drying function according to claim 1, characterized in that, A plastic sleeve (30) is arranged between the device shell (1) and the spin-drying cylinder (35), the plastic sleeve (30) is arranged outside the spin-drying cylinder (35), and the outer wall of the plastic sleeve (30) is fixedly connected to the inner wall of the device shell (1) through a plurality of suspension springs (31).

8. The coal-bed gas content testing device with drying function according to claim 1, characterized in that, The data acquisition system includes an electronic flow sensor (23) and a methane concentration sensor (24) located inside the exhaust pipe (21). It also includes a temperature sensor and an atmospheric pressure sensor for detecting the ambient temperature and air pressure of the entire test device.

9. The coal-bed gas content testing device with drying function according to claim 1, characterized in that, Multiple support feet (32) are fixedly provided on the outer wall of the device housing (1).

10. A coal seam gas content testing method using the coal seam gas content testing device with a drying function according to claim 1, characterized in that, Includes the following: First, place the coal sample into the drying cylinder (35) and seal it by closing the sealing cover (29), drain valve (34) and exhaust valve (22); Then, the coal sample is spun dry, dried and crushed using a spun dry system and a crushing system. After the spun dry system and crushing system have finished working, they are turned off and left to stand for 3 minutes. Finally, open the exhaust valve (22), use the data acquisition system to collect the total flow rate of the gas desorbed from the coal sample in the exhaust pipe (21) and the concentration of methane in the gas, as well as the temperature and pressure of the external environment of the test device, and upload them to the data acquisition system. The data processing system uses data collected by the data acquisition system to calculate the gas content of the coal seam. The specific process is as follows: The flow rate of methane desorbed from the coal sample in the exhaust pipe (21) is calculated which satisfies the following equation: ； wherein: is the flow rate of methane in the desorbed gas from the coal sample; q is the total flow rate of the desorbed gas from the coal sample; and c is the concentration of methane in the desorbed gas from the coal sample. According to the gas flow equation, the flow rate of methane desorbed from the coal sample in the exhaust pipe (21) is converted into the flow rate of methane under the atmospheric pressure conditions of the external environment of the test device which satisfies the following equation: ； In the formula: P is the external ambient air pressure of the test device; W is the external ambient temperature of the test device; The flow rate of methane under the atmospheric pressure condition of the external environment of the testing device is tested again The gas content Q of the coal seam is calculated, which satisfies the following formula: ； In the formula: Q is the gas content of the coal seam; T is the cumulative test time; M is the mass of the coal sample.

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