Coal seam gas content determination method

Abstract

The invention discloses a coal seam gas content determination method. The method comprises the following steps: collecting a coal sample and placing the coal sample in a coal sample closed desorption container for closed normal-pressure desorption; opening the corresponding branches based on the change of the gas flow; working condition flow data and corrected gas flow data in the standard state are determined based on the laminar flow sensors on the branches and measurement data of the environment temperature sensor and the environment pressure sensor, and then the loss amount is calculated; the coal sample crushing device crushes the coal sample, and the corresponding branch is opened again based on the change of the gas flow until the desorption work is stopped; based on measurement data of each sensor, the coal sample mass is calculated to finally determine the coal seam gas content. The parameters such as the temperature, the pressure and the pressure difference of fluid flowing through the laminar flow sensor are measured in real time, the flow in a standard state is obtained after calculation and correction, and the measured gas flow and volume data are more scientific and accurate through temperature and pressure compensation.

Description

Technical Field

[0001] The invention relates to the technical field of coal seam gas content determination, in particular to a coal seam gas content determination method. Background Art

[0002] Coalbed gas is a compressible mixed gas composed of CH4, CO2, N2, and varying amounts of heavy hydrocarbons and trace amounts of rare gases. It is greatly affected by temperature and pressure at normal pressure. The temperature and pressure effects should be considered and corrected when measuring gas flow. Coalbed gas content is an important basic parameter for determining the level of gas disasters, gas extraction, and prevention and control of coal and gas outbursts, but there are different standard states in gas disaster management due to different application scenarios. For example, the coalbed gas content measured in the "Direct Underground Determination Method of Coalbed Gas Content" (GB / T23250-2009) is the gas content at 273.15K (0℃) and 101.325KPa; the pure amount of gas extracted in the "Design Standard for Coal Mine Gas Extraction Engineering" (GB 50471-2018) refers to the gas content at 293.15K (20℃) and 101.325KPa. In addition, gas is slightly soluble in water. Under the conditions of 293.15K (20℃) and 101.325KPa, the solubility is 3.5L / 100L water. When the drainage gas collection method is used, the gas content will be low due to factors such as gas dissolved in water and changes in water column pressure.

[0003] Existing solutions in this field use direct desorption of broken coal bodies underground, which causes the temperature of the desorbed gas to increase significantly, resulting in an increase in the measured gas content of the coal seam. At the same time, the installed temperature sensors and gas pressure sensors are used to measure the ambient temperature and atmospheric pressure, which are in different positions from the flow sensors that measure the gas flow. The gas state changes, and the pressure loss caused by the gas flowing through the flow sensor is not considered, resulting in inaccurate test flow and further distortion of the gas content test. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention proposes a method for measuring the gas content in coal seams. The method has high measurement accuracy, fast speed, and high intelligence, complies with existing national standards, and can greatly improve the accuracy and efficiency of measuring the gas content in coal seams underground in coal mines.

[0005] The present invention discloses a method for measuring coal seam gas content, comprising:

[0006] S1: Collect coal samples and place them in a coal sample closed desorption container for closed atmospheric pressure desorption;

[0007] S2: When the gas flow rate reaches the corresponding opening preset value, the corresponding branch is opened, and the other branches are closed; whenever the gas flow rate drops to the opening range of the corresponding branch, the branch is opened, and the other branches are closed; wherein each branch is respectively connected to a coal sample closed desorption container;

[0008] The data processing terminal determines the corrected standard state gas flow data based on the measurement data of the laminar flow sensors on each branch, and determines the corrected working condition flow data based on the measurement data of the ambient temperature sensor and the ambient pressure sensor; wherein the ambient temperature sensor and the ambient pressure sensor are used to measure the fluid temperature and pressure of the working environment;

[0009] S3: When the gas desorption reaches a corresponding time, or when the gas flow rate decreases to a corresponding value, the data processing terminal starts the coal sample crushing device to crush the coal sample; wherein the coal sample crushing device is arranged in a coal sample closed desorption container;

[0010] S4: When the gas flow rate reaches the corresponding opening threshold, the corresponding branch is opened and other branches are closed; when the gas flow rate decreases to the corresponding closing preset value, the gas desorption work is stopped;

[0011] S5: The data processing terminal calculates the desorbed gas volume based on the measurement data of the laminar flow sensor, the ambient pressure sensor, and the ambient temperature sensor, and deduces the lost gas volume;

[0012] S6: The mass of the coal sample is obtained by weighing, and the desorbable gas content is obtained by dividing the sum of the desorbed gas volume and the lost gas volume by the mass of the coal sample;

[0013] S7: The desorbable gas content is added to the non-desorbable gas content calculated by the data processing terminal to obtain the coal seam gas content actually measured underground in the coal mine.

[0014] Furthermore, the step S2 comprises:

[0015] When the gas flow rate is measured to be 1500 SCCM, the data processing terminal controls the opening of the solenoid valve on the corresponding branch and controls the closing of the solenoid valves on other branches, and the gas flows through the laminar flow sensor on the branch;

[0016] When the measured gas flow rate drops to 450 SCCM, the data processing terminal controls the opening of the solenoid valve on the corresponding branch and controls the closing of the solenoid valves on other branches, and the gas flows through the laminar flow sensor on the branch;

[0017] When the measured gas flow rate drops to 45 SCCM, the data processing terminal controls the opening of the solenoid valve on the corresponding branch and controls the closing of the solenoid valves on other branches, and the gas flows through the laminar flow sensor on the branch;

[0018] The data processing terminal determines the corrected standard state gas flow data based on the measurement data of the laminar flow sensors on each branch, and determines the corrected working condition flow data based on the measurement data of the ambient temperature sensor and the ambient pressure sensor.

[0019] Further, the laminar flow sensor comprises a laminar flow element arranged on the corresponding branch, and the laminar flow element is provided with: a pressure difference sensor device for measuring the inlet and outlet pressure difference, a tail pressure sensor for measuring the temperature and pressure of the fluid flowing through the laminar flow element, and a tail temperature sensor;

[0020] Furthermore, the corrected standard state gas flow data is determined based on the following expression:

[0021]

[0022] Where Q0 is the volume flow rate under standard conditions; r is the inner diameter of the laminar flow element; η is the viscosity coefficient of the fluid; L is the length of the laminar flow element; P i is the inlet pressure of the laminar flow element; P0 is the outlet pressure of the laminar flow element; P1 is the pressure of the fluid flowing through the laminar flow element; T0 is the temperature of the fluid in the standard state; T1 is the temperature of the fluid flowing through the laminar flow element.

[0023] Furthermore, the corrected operating flow data is determined based on the following expression:

[0024]

[0025] Among them, Q g is the volume flow rate under working condition; P i is the inlet pressure of the laminar flow element; P0 is the outlet pressure of the laminar flow element; P1 is the pressure of the fluid in the standard state; P2 is the fluid pressure in the working environment; r is the inner diameter of the laminar flow element; η is the viscosity coefficient of the fluid; L is the length of the laminar flow element; T1 is the temperature of the fluid flowing through the laminar flow element; T2 is the temperature of the fluid in the standard state.

[0026] Furthermore, the step S3 includes:

[0027] When the data processing terminal measures that the gas desorption time reaches 30 minutes, or the gas flow rate is less than 2 SCCM, the data processing terminal starts the coal sample crushing device to crush the coal sample;

[0028] Furthermore, the step S4 comprises:

[0029] When the gas flow rate is measured to be 450 SCCM, the data processing terminal controls the opening of the solenoid valve on the corresponding branch and controls the closing of the solenoid valves on other branches, and the gas flows through the laminar flow sensor on the branch;

[0030] When the gas flow rate is measured to be less than 0.5 SCCM, the gas desorption process is stopped.

[0031] Furthermore, the step S7 also includes: transmitting the coal seam gas content from the data processing terminal to the underground base station via a wireless transmitter, and transmitting it from the underground base station to the ground system via the underground high-speed communication network.

[0032] The present invention has at least the following beneficial effects:

[0033] The present invention realizes direct crushing and desorption of coal samples underground through a coal sample crushing device, which greatly shortens the gas content test time. The temperature, pressure, pressure difference and other parameters of the fluid flowing through the laminar flow sensor are measured in real time, and the flow rate under the standard state is obtained after calculation and correction. The measured flow data is made more scientific and accurate through temperature and pressure compensation, and the flow measurement error caused by the increase of the temperature of the coal body and the desorbed gas caused by the crushing of the coal sample is avoided. The temperature and pressure parameters of the working environment perceived in real time by the ambient temperature sensor and the ambient pressure sensor are calculated and corrected to obtain the flow data under the ambient state, avoiding the error caused by the change of pressure and temperature after the fluid passes through the flow sensor. The combination of the ambient pressure sensor, the ambient temperature sensor and the flow sensor also avoids the error caused by the pressure and temperature data of the flow sensor. The present invention has high measurement accuracy, fast speed and high intelligence, meets the existing national standards, and can greatly improve the accuracy of the measurement of coal seam gas content in coal mines.

[0034] Other beneficial effects of the present invention will be described in detail in the specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 The invention discloses a flow chart of a method for determining gas content in a coal seam.

[0037] Figure 2 This is a schematic diagram of the working principle of the coal seam gas content measuring device disclosed in Example 1.

[0038] Figure 3This is a schematic diagram of the structure of the laminar flow sensor disclosed in Example 1.

[0039] 11-coal sample crushing device, 12-coal sample, 13-coal sample closed desorption container, 14-valve, 21-solenoid valve I, 22-solenoid valve II, 23-solenoid valve III, 31-laminar flow sensor I, 32-laminar flow sensor II, 33-laminar flow sensor III, 4-transmission control cable, 51-tee connector I, 52-tee connector II, 601-inlet pipeline, 602-outlet pipeline, 611-first branch, 612-second branch, 613-third branch, 7-ambient pressure sensor, 8-ambient temperature sensor, 9-data processing terminal, 301-inlet pressure sensor, 302-outlet pressure sensor, 303-tail pressure sensor, 304-tail temperature sensor, 305-laminar flow element. DETAILED DESCRIPTION

[0040] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0041] like Figure 1 As shown, the present invention discloses a method for determining coal seam gas content, comprising:

[0042] S1: Collect coal samples and place them in a coal sample closed desorption container for closed atmospheric pressure desorption;

[0043] S2: When the gas flow rate reaches the corresponding opening preset value, the corresponding branch is opened, and the other branches are closed; whenever the gas flow rate drops to the opening range of the corresponding branch, the branch is opened, and the other branches are closed; wherein each branch is respectively connected to a coal sample closed desorption container;

[0044] The data processing terminal determines the corrected standard state gas flow data based on the measurement data of the laminar flow sensors on each branch, and determines the corrected working condition flow data based on the measurement data of the ambient temperature sensor and the ambient pressure sensor; wherein the ambient temperature sensor and the ambient pressure sensor are used to measure the fluid temperature and pressure of the working environment;

[0045] S3: When the gas desorption reaches a corresponding time, or when the gas flow rate decreases to a corresponding value, the data processing terminal starts the coal sample crushing device to crush the coal sample; wherein the coal sample crushing device is arranged in a coal sample closed desorption container;

[0046] S4: When the gas flow rate reaches the corresponding opening threshold, the corresponding branch is opened and other branches are closed; when the gas flow rate decreases to the corresponding closing preset value, the gas desorption work is stopped;

[0047] S5: The data processing terminal calculates the desorbed gas volume based on the measurement data of the laminar flow sensor, the ambient pressure sensor, and the ambient temperature sensor, and deduces the lost gas volume;

[0048] S6: The mass of the coal sample is obtained by weighing, and the desorbable gas content is obtained by dividing the sum of the desorbed gas volume and the lost gas volume by the mass of the coal sample;

[0049] S7: The desorbable gas content is added to the non-desorbable gas content calculated by the data processing terminal to obtain the coal seam gas content actually measured underground in the coal mine.

[0050] The present invention is described in detail below in conjunction with the following embodiments.

[0051] Embodiment 1

[0052] See also Figure 2 and Figure 3 This embodiment discloses a coal seam gas content determination device, which is used to implement the above-mentioned coal seam gas content determination method, and the device includes: a flow sensor combination based on temperature and pressure compensation, a pipeline mechanism, a coal sample sealed desorption container 13, a coal sample crushing device 11, an ambient temperature sensor 8, an ambient pressure sensor 7, and a data processing terminal 9. The container cover above the coal sample sealed desorption container 13 is provided with an opening, and the air intake pipeline is connected to the coal sample sealed desorption container 13 through the opening. A valve 14 for controlling the on-off is also provided between the opening and the coal sample sealed desorption container 13, and the valve 14 is electrically connected to the data processing terminal 9. The coal sample 12 is crushed by the coal sample crushing device 11 with high-speed rotation, and the coal sample naturally desorbed gas and the coal sample crushed desorbed gas enter through the inlet of the temperature and pressure compensation flow sensor combination, and the outlet of the flow sensor combination is connected to the atmosphere.

[0053] The pipeline mechanism includes: an air inlet pipeline 601 connected to the coal sample sealed desorption container, an air outlet pipeline 602 connected to the external environment, and a plurality of branches arranged in parallel between the air inlet pipeline 601 and the air outlet pipeline 602 .

[0054] The flow sensor assembly is electrically connected to the data processing terminal via a transmission control cable 4. The flow sensor assembly mainly includes: a plurality of laminar flow sensors and a plurality of electromagnetic valves. Figure 1As shown, there are three parallel branches in the pipeline mechanism: the first branch 611, the second branch 612 and the third branch 613, the two ends of which are respectively connected to the air inlet pipeline 601 and the air outlet pipeline 602, wherein the second branch 612 is connected to the air inlet pipeline 601 through the three-way joint I51, and the third branch 613 is connected to the air inlet pipeline 601 through the three-way joint II52. The first branch 611 is provided with a solenoid valve I21 and a laminar flow sensor I31, the second branch 612 is provided with a solenoid valve II22 and a laminar flow sensor II32, and the third branch 613 is provided with a solenoid valve III23 and a laminar flow sensor III33.

[0055] The data processing terminal 9 is connected to the data ends of each laminar flow sensor, the ambient temperature sensor 8, and the ambient pressure sensor 7. The measuring ends of the ambient temperature sensor 8 and the ambient pressure sensor 7 are connected to the ambient gas to sense the temperature and atmospheric pressure of the working environment in real time. The fluid passes through the measuring end of any laminar flow sensor, the data end of the laminar flow sensor is connected to the data processing terminal 9, the inlet of the solenoid valve is connected to the outlet of the measured fluid, and the outlet of the solenoid valve is connected to the laminar flow sensor. The data processing terminal 9 controls the opening and closing of different solenoid valves based on the measured fluid flow through the laminar flow sensor.

[0056] See also Figure 3 The laminar flow sensor described in this embodiment is mainly composed of a laminar flow element 305, an inlet pressure sensor 301, an outlet pressure sensor 302, a tail temperature sensor 304, and a tail pressure sensor 303. The data ends of the inlet pressure sensor 301, the outlet pressure sensor 302, the tail temperature sensor 304, and the tail pressure sensor 303 are connected to the data processing terminal 9, and the measuring ends of the inlet pressure sensor 301, the outlet pressure sensor 302, the tail temperature sensor 304, and the tail pressure sensor 303 are connected to the laminar flow element 305.

[0057] In this embodiment, the number of laminar flow sensors in the flow sensor combination based on temperature and pressure compensation is 3, the measurement range is 0.01% to 100% of the full scale, the data acquisition frequency is not less than 50Hz, and the measurement ranges are: the range of laminar flow sensor I 31 is 0 to 2000SCCM, the range of laminar flow sensor II 32 is 0 to 500SCCM; the range of laminar flow sensor III 33 is 0 to 50SCCM. The measurement accuracy of the tail temperature sensor 304 is 0.01K, and the measurement accuracy of the inlet pressure sensor 301, the outlet pressure sensor 302, and the tail pressure sensor 303 is 100pa.

[0058] The measurement range of the gas flow sensor combination based on temperature and pressure compensation is seamlessly converted. The data processing terminal 9 automatically controls the opening and closing of the solenoid valve according to the flow data actually measured by each laminar flow sensor to ensure that the fluid flow is within the measurement range of the operating laminar flow sensor;

[0059] Embodiment 2

[0060] This embodiment discloses a method for measuring coal seam gas content, comprising the following steps:

[0061] ① Collect coal samples in the coal mine using fixed-point sampling method according to the design, and place the coal samples in a closed desorption container.

[0062] ② The gas desorbed from the coal sample is measured by a flow sensor combination based on temperature and pressure compensation. When the gas flow rate is 1500 SCCM (SCCM, standard cubic centimeterperminute, standard cubic centimeter per minute), the data processing terminal 9 controls the closing of electromagnetic valve II 22 and electromagnetic valve III 23, and the opening of electromagnetic valve I 21, and the gas flows through the laminar flow sensor I 31. The tail temperature sensor 304 and the tail pressure sensor 303 at the outlet of the laminar flow element 305 of the laminar flow sensor I 31 obtain that the temperature and pressure of the gas flowing through the laminar flow element 305 are 27°C (300.15K) and 86100Pa, respectively. The data are transmitted to the data processing terminal 9 in real time and corrected by the standard flow correction formula to obtain a gas flow rate of 1159.95SCCM in the standard state (273.15K, 101325Pa). The temperature and pressure of the working environment (working condition) sensed in real time by the ambient temperature sensor 8 and the ambient pressure sensor 7 are 25.5°C (300.15K) and 91100Pa. The gas flow rate is corrected by the working condition flow correction formula to obtain the working condition flow data of 1410.59SCCM.

[0063] When the gas flow rate is sensed to be 450 SCCM, the data processing terminal 9 controls the closing of solenoid valve I21 and solenoid valve III23, and the opening of solenoid valve II22. The gas flows through the laminar flow sensor II32. The tail temperature sensor 304 and the tail pressure sensor 303 at the outlet of the laminar flow element 305 of the laminar flow sensor II32 obtain that the temperature and pressure of the gas flowing through the laminar flow element 305 are 27°C (300.15K) and 86100 Pa, respectively. The data is transmitted to the data processing terminal 9 in real time and corrected using the standard flow correction formula to obtain a standard gas flow rate of 347.99 SCCM. The temperature and pressure of the working environment (working conditions) sensed in real time by the ambient temperature sensor 8 and the ambient pressure sensor 7 are 25.5°C (300.15K) and 91100 Pa, respectively. The gas flow rate is corrected by the working condition flow correction formula to obtain the working condition flow data of 423.18 SCCM.

[0064] The corrected standard gas flow data is determined based on the following expression:

[0065]

[0066] Where Q0 is the volume flow rate under standard conditions; r is the inner diameter of the laminar flow element; η is the viscosity coefficient of the fluid; L is the length of the laminar flow element; P i is the inlet pressure of the laminar flow element; P0 is the outlet pressure of the laminar flow element; P1 is the pressure of the fluid flowing through the laminar flow element; T0 is the temperature of the fluid in the standard state; T1 is the temperature of the fluid flowing through the laminar flow element.

[0067] The corrected operating flow data is determined based on the following expression:

[0068]

[0069] Among them, Q g is the volume flow rate under working condition; P i is the inlet pressure of the laminar flow element; P0 is the outlet pressure of the laminar flow element; P1 is the pressure of the fluid in the standard state; P2 is the fluid pressure in the working environment; r is the inner diameter of the laminar flow element; η is the viscosity coefficient of the fluid; L is the length of the laminar flow element; T1 is the temperature of the fluid flowing through the laminar flow element; T2 is the temperature of the fluid in the standard state.

[0070] When the gas flow rate is sensed to be 45 SCCM, the data processing terminal 9 controls the closing of solenoid valve I21 and solenoid valve II22, and the opening of solenoid valve III23, and the gas flows through the laminar flow sensor III33. The tail temperature sensor 304 and the tail pressure sensor 303 at the outlet of the laminar flow element 305 of the laminar flow sensor III33 obtain that the temperature and pressure of the gas flowing through the laminar flow element 305 are 27°C (300.15K) and 86100 Pa, respectively. The data is transmitted to the data processing terminal 9 in real time and corrected using the standard flow correction formula to obtain a standard gas flow rate of 34.8 SCCM. The temperature and pressure of the working environment (working conditions) sensed in real time by the ambient temperature sensor 8 and the ambient pressure sensor 7 are 25.5°C (300.15K) and 91100 Pa, respectively. The gas flow rate is corrected by the working condition flow correction formula to obtain the working condition flow data of 42.32 SCCM.

[0071] ③ When the data processing terminal 9 measures that the gas desorption time is 30 minutes or the gas flow rate is less than 2 SCCM, the data processing terminal 9 starts the coal sample crushing device 11 according to the program to crush the coal sample, causing the coal sample and the desorbed gas to heat up, and continues to measure the gas flow rate of coal sample desorption according to the above step ②.

[0072] Specifically, when the gas flow rate is sensed to be 450 SCCM, the data processing terminal 9 controls the closing of solenoid valve I21 and solenoid valve III23, and the opening of solenoid valve II22. The gas flows through the laminar flow sensor II32. The tail temperature sensor 304 and the tail pressure sensor 303 at the outlet of the laminar flow element of the laminar flow sensor II32 obtain that the temperature and pressure of the gas flowing through the laminar flow element are 50°C (323.15K) and 89100 Pa, respectively. The data is transmitted to the data processing terminal 9 in real time and corrected using the standard flow correction formula to obtain a standard gas flow rate of 334.48 SCCM. The temperature and pressure of the working environment (working conditions) sensed in real time by the ambient temperature sensor 8 and the ambient pressure sensor 7 are 25.5°C (300.15K) and 91100 Pa, respectively. The gas flow rate is corrected by the working condition flow correction formula to obtain the working condition flow data of 406.75 SCCM. The gas desorption work is stopped when the gas flow rate is less than 0.5 SCCM.

[0073] ④ In the process of measuring the gas content underground, the data processing terminal 9 stores the data collected by each sensor in real time, calculates the desorbed gas volume, and calculates the lost gas volume according to the set program.

[0074] ⑤ The mass of coal sample 12 is obtained by weighing, and the desorbable gas content is obtained by dividing the sum of the desorbed gas volume and the lost gas volume by the mass of the coal sample.

[0075] ⑥ The desorbable gas content is added to the non-desorbable content calculated by the data processing terminal 9 to obtain the coal seam gas content actually measured underground in the coal mine. The data processing terminal 9 transmits it to the underground base station through a wireless transmitter, and the underground base station transmits it to the ground central control room through the underground high-speed communication network.

[0076] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for determining coal seam gas content, characterized in that: include: S1: Collect coal samples and place them in a coal sample closed desorption container for closed atmospheric pressure desorption; S2: When the gas flow rate reaches the corresponding opening preset value, the corresponding branch is opened, and the other branches are closed; whenever the gas flow rate drops to the opening range of the corresponding branch, the branch is opened, and the other branches are closed; wherein each branch is respectively connected to a coal sample closed desorption container; The data processing terminal determines the corrected standard state gas flow data based on the measurement data of the laminar flow sensors on each branch, and determines the corrected working condition flow data based on the measurement data of the ambient temperature sensor and the ambient pressure sensor; wherein the ambient temperature sensor and the ambient pressure sensor are used to measure the fluid temperature and pressure of the working environment; S3: When the gas desorption reaches a corresponding time, or when the gas flow rate decreases to a corresponding value, the data processing terminal starts the coal sample crushing device to crush the coal sample; wherein the coal sample crushing device is arranged in a coal sample closed desorption container; S4: When the gas flow rate reaches the corresponding opening threshold, the corresponding branch is opened and other branches are closed; when the gas flow rate decreases to the corresponding closing preset value, the gas desorption work is stopped; S5: The data processing terminal calculates the desorbed gas volume based on the measurement data of the laminar flow sensor, the ambient pressure sensor, and the ambient temperature sensor, and deduces the lost gas volume; S6: The mass of the coal sample is obtained by weighing, and the desorbable gas content is obtained by dividing the sum of the desorbed gas volume and the lost gas volume by the mass of the coal sample; S7: The desorbable gas content is added to the non-desorbable gas content calculated by the data processing terminal to obtain the coal seam gas content actually measured underground in the coal mine.

2. The method for determining coal seam gas content according to claim 1, characterized in that: The step S2 comprises: When the gas flow rate is measured to be 1500 SCCM, the data processing terminal controls the opening of the solenoid valve on the corresponding branch and controls the closing of the solenoid valves on other branches, and the gas flows through the laminar flow sensor on the branch; When the measured gas flow rate drops to 450 SCCM, the data processing terminal controls the opening of the solenoid valve on the corresponding branch and controls the closing of the solenoid valves on other branches, and the gas flows through the laminar flow sensor on the branch; When the measured gas flow rate drops to 45 SCCM, the data processing terminal controls the opening of the solenoid valve on the corresponding branch and controls the closing of the solenoid valves on other branches, and the gas flows through the laminar flow sensor on the branch; The data processing terminal determines the corrected standard state gas flow data based on the measurement data of the laminar flow sensors on each branch, and determines the corrected working condition flow data based on the measurement data of the ambient temperature sensor and the ambient pressure sensor.

3. The method for determining coal seam gas content according to claim 1, characterized in that: The laminar flow sensor comprises a laminar flow element arranged on the corresponding branch, and the laminar flow element is provided with: a pressure difference sensor device for measuring the inlet and outlet pressure difference, a tail pressure sensor for measuring the temperature and pressure of the fluid flowing through the laminar flow element, and a tail temperature sensor.

4. The method for determining coal seam gas content according to claim 3, characterized in that: The corrected standard gas flow data is determined based on the following expression: Where Q0 is the volume flow rate under standard conditions; r is the inner diameter of the laminar flow element; η is the viscosity coefficient of the fluid; L is the length of the laminar flow element; P i is the inlet pressure of the laminar flow element; P0 is the outlet pressure of the laminar flow element; P1 is the pressure of the fluid flowing through the laminar flow element; T0 is the temperature of the fluid in the standard state; T1 is the temperature of the fluid flowing through the laminar flow element.

5. The method for determining coal seam gas content according to claim 4, characterized in that: The corrected operating flow data is determined based on the following expression: Among them, Q g is the volume flow rate under working condition; P i is the inlet pressure of the laminar flow element; P0 is the outlet pressure of the laminar flow element; P1 is the pressure of the fluid in the standard state; P2 is the fluid pressure in the working environment; r is the inner diameter of the laminar flow element; η is the viscosity coefficient of the fluid; L is the length of the laminar flow element; T1 is the temperature of the fluid flowing through the laminar flow element; T2 is the temperature of the fluid in the standard state.

6. The method for determining coal seam gas content according to claim 2, characterized in that: The step S3 comprises: When the data processing terminal measures that the gas desorption time reaches 30 minutes, or the gas flow rate is less than 2 SCCM, the data processing terminal turns on the coal sample crushing device to crush the coal sample.

7. The method for measuring coal seam gas content according to claim 6, characterized in that: The step S4 comprises: When the gas flow rate is measured to be 450 SCCM, the data processing terminal controls the opening of the solenoid valve on the corresponding branch and controls the closing of the solenoid valves on other branches, and the gas flows through the laminar flow sensor on the branch; When the gas flow rate is measured to be less than 0.5 SCCM, the gas desorption process is stopped.

8. The method for measuring coal seam gas content according to claim 7, characterized in that: The step S7 also includes: transmitting the coal seam gas content test data from the data processing terminal to the ground system through the underground communication network.

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