A gas extraction intelligent control experimental system and method

Abstract

The present invention discloses a gas extraction intelligent control experimental system and method, comprising an extraction branch pipe subsystem, an extraction main pipe system, a monitoring and control subsystem, a signal analysis and processing subsystem and an extraction management platform. The extraction main pipe system cooperates with the extraction branch pipe subsystem to effectively simulate the influence of coal seam gas extractability and air leakage degree on the adjustment of extraction parameters. At the same time, the opening of each electric regulating valve and the rotation speed of the extraction pump are adjusted by the signal analysis and processing subsystem and the monitoring and control subsystem to achieve the adjustment of gas concentration and pure flow under different working conditions. The extraction management platform takes the maximum gas pure flow of the extraction main pipe as the target to solve and obtain the optimal system operation parameters; by simulating the flow of underground gas in the extraction system, the relationship between system parameters and gas concentration and flow in the pipeline network is clarified, thereby providing data support for the intelligent adjustment of parameters of the underground extraction system to ensure high extraction concentration and low energy consumption.

Description

Technical Field

[0001] The invention relates to a gas extraction intelligent control experimental system and method, belonging to the technical field of gas extraction in coal mines. Background Art

[0002] Underground gas extraction in coal mines is an important part of my country's coalbed methane production. The safe and efficient extraction of coalbed methane is of great significance for the effective utilization of resources and ensuring the safety of coal mine production. For gas mines, "extraction before extraction" has become a necessary link in the process of coal resource extraction. Borehole extraction is an important measure for underground gas extraction. The gas extraction system uses a negative pressure pump to extract gas from the borehole, which is the key to ensuring efficient gas extraction. my country's coal seams generally have the characteristics of "low porosity and low permeability", which leads to a series of problems such as difficulty in gas extraction and low extraction efficiency. For difficult-to-extract coal seams, negative pressure is usually increased for extraction. While increasing negative pressure to increase gas extraction volume will also aggravate borehole leakage, resulting in a decrease in gas concentration. Depending on whether the methane concentration exceeds 30%, gas can be divided into high-concentration gas and low-concentration gas. The explosion limit of gas is 5% to 16%. Low-concentration gas has disaster risks during transportation in gas pipelines. In addition, excessively high negative extraction pressure will inevitably lead to high-power operation of the extraction pump and increase the flow resistance of gas in the pipeline. The high energy consumption of the gas extraction system and the difficulty in utilizing low-concentration gas have greatly reduced the economic efficiency of gas extraction, resulting in an imbalance between input and output of underground gas extraction.

[0003] Intelligent regulation of underground gas extraction systems is a fundamental solution to achieve accurate gas extraction and reduce energy consumption. At present, the regulation of gas extraction systems mainly relies on manual work and lacks real-time intelligent regulation. Reasonable adaptation of borehole extraction negative pressure, adaptive adjustment of extraction pump power, and comprehensive monitoring of multiple parameters have not been effectively carried out. How to simulate the flow of underground gas in the extraction system through experiments, clarify the relationship between system parameters and gas concentration and flow in the pipeline network, and provide data support for intelligent parameter adjustment of underground extraction systems to ensure higher extraction concentration and relatively low energy consumption is a problem that needs to be solved urgently. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention provides a gas extraction intelligent control experimental system and method, which can simulate the flow of underground gas in the extraction system, clarify the relationship between system parameters and the gas concentration and flow rate in the pipeline network, thereby providing data support for the intelligent adjustment of parameters of the underground extraction system to ensure a higher extraction concentration and relatively low energy consumption.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a gas extraction intelligent control experimental system, including an extraction branch pipe subsystem, an extraction main pipe system, a monitoring and control subsystem, a signal analysis and processing subsystem, an industrial ring network and an extraction management platform;

[0006] The extraction branch pipe subsystem includes a methane gas cylinder, a methane storage tank, a core clamp, a confining pressure pump and a borehole air leakage simulation device. The methane gas cylinder is connected to the inlet of the methane storage tank for conveying gas to the methane storage tank; a coal core is arranged in the core clamp, and the confining pressure pump is connected to the core clamp for applying confining pressure to the coal core by the core clamp; the outlet of the methane storage tank is connected to the extraction main pipe system through the extraction branch pipe through the core clamp for conveying gas into the core clamp and transmitting it to the extraction main pipe system after passing through the coal core; the borehole air leakage simulation device includes a rectangular shell and a crushed coal sample, the crushed coal sample is installed in the rectangular shell, a plurality of circular holes are provided on one side of the rectangular shell, and the rectangular shell is connected to the extraction branch pipe through a pipeline for allowing air to enter the rectangular shell through the circular holes and be conveyed to the extraction branch pipe after flowing through the crushed coal sample;

[0007] The extraction main pipe system includes an extraction main pipe, an extraction pump and a gas collection device. The gas collection device is connected to the extraction pump through the extraction main pipe. The extraction pump is used to generate extraction negative pressure in the extraction main pipe. The extraction main pipe is used to transport the gas transported by the extraction branch pipe to the gas collection device for storage under the action of negative pressure.

[0008] The monitoring and control subsystem includes a gas pressure sensor, a flow-negative pressure sensor I, a flow-negative pressure sensor II, a comprehensive monitoring instrument, an electric regulating valve I, an electric regulating valve II, an electric regulating valve III, an electric regulating valve IV, an electric regulating valve V, a frequency converter and a PLC comprehensive control platform; the gas pressure sensor is installed on the methane storage tank to monitor the gas pressure inside the methane storage tank; the flow-negative pressure sensor I is installed on the extraction branch pipe between the core holder and the drilling leakage simulation device to monitor the methane flow out of the core holder and the negative pressure at that position; the flow-negative pressure sensor II is installed on the extraction branch pipe between the drilling leakage simulation device and the extraction main pipe to monitor the mixed gas flow of methane and air flowing into the drilling leakage simulation device and the negative pressure at that position; the comprehensive monitoring instrument is installed on the extraction main pipe to monitor the gas flow, methane concentration and negative pressure in the extraction main pipe; the electric regulating valve I is installed between the core holder and the drilling leakage simulation device. The electric regulating valve II is installed on the extraction branch pipe between the drilling air leakage simulation device and the extraction main pipe to control the flow of methane flowing out of the core clamp; the electric regulating valve II is installed on the extraction branch pipe between the drilling air leakage simulation device and the extraction main pipe to control the flow of methane and air mixed gas entering the extraction main pipe; the electric regulating valve III is installed on the extraction main pipe to control the extraction gas flow of the extraction main pipe; the electric regulating valve IV is installed on the pipeline between the methane gas cylinder and the methane storage tank to control the methane flow injected into the methane storage tank; the electric regulating valve V is installed on the pipeline between the drilling air leakage simulation device and the extraction branch pipe to control the leakage flow; the frequency converter is connected to the extraction pump to adjust the speed of the extraction pump; the PLC integrated control platform receives data fed back by the gas pressure sensor, the flow-negative pressure sensor I, the flow-negative pressure sensor II and the integrated monitoring instrument, and adjusts the opening of the electric regulating valve I, the electric regulating valve II, the electric regulating valve III, the electric regulating valve IV and the electric regulating valve V and the frequency converter;

[0009] The signal analysis and processing subsystem includes a temperature sensor, a signal processor and a signal analyzer. The temperature sensor is installed in a rectangular housing and is used to monitor the real-time temperature value of the crushed coal sample and feed it back to the signal processor. The signal processor processes the received signal and feeds it back to the signal analyzer.

[0010] The industrial ring network is used to transmit data from the PLC integrated control platform to the extraction management platform;

[0011] The extraction management platform is used to receive data from the industrial ring network and signal analyzer, and achieve optimal parameter settings for the experimental system through data analysis and display the feedback data in real time.

[0012] Furthermore, the main extraction pipe and the branch extraction pipe are both made of stainless steel pipes, which can effectively extend the service life of the pipes and ensure the stability of the experiment.

[0013] Furthermore, the extraction branch pipe is threadedly connected to the extraction main pipe. This structure is easy to disassemble and install, and the connection is stable.

[0014] Furthermore, the plurality of circular holes are evenly distributed on one side of the rectangular shell. This arrangement can ensure that air evenly enters the rectangular shell from different circular holes.

[0015] Furthermore, the side of the rectangular shell with the circular hole is a detachable baffle, and the other sides are insulation plates. This structure makes it convenient to fill the crushed coal sample and reduces the loss of heat generated by the reaction between air and coal sample.

[0016] Furthermore, there are multiple extraction branch pipe subsystems and integrated monitoring instruments, each of which is installed near the connection between each extraction branch pipe subsystem and the extraction main pipe. By setting multiple, it is possible to simulate gas extraction under different working conditions, which is convenient for obtaining experimental data of subsequent corresponding working conditions.

[0017] The working method of the above-mentioned gas extraction intelligent control experimental system has the following specific steps:

[0018] ①. Turn on the power supply, close the electric regulating valve V through the PLC integrated control platform, open the electric regulating valves I, II, III and IV and keep them at the maximum opening, monitor the real-time pressure in the methane storage tank through the gas pressure sensor, and temporarily close the electric regulating valve IV when the gas pressure in the methane storage tank reaches the preset value;

[0019] ② When the flow-negative pressure sensor I and the flow-negative pressure sensor II detect that methane gas passes through the coal core in the core holder, the extraction pump is turned on to work at a preset speed. During the extraction process, when the extraction main flow obtained by the integrated monitor closest to the extraction pump is the sum of the flow rates monitored by the flow-negative pressure sensors I on each extraction branch pipe and the methane concentrations monitored by each integrated monitor are the same, the system is considered to be airtight;

[0020] ③. Open the electric regulating valve IV to restore the gas pressure in the methane storage tank to the preset value, and then adjust its opening to keep the gas pressure in the methane storage tank at a constant preset value. The electric regulating valve I is controlled by the PLC integrated control platform to continuously reduce the opening by 5% from the maximum opening, so as to realize the exponential attenuation of the gas flow over time;

[0021] ④. Fill the rectangular shell with crushed coal samples, and control the electric regulating valve V to the maximum opening through the PLC integrated control platform to simulate the air leakage from the crushed coal around the borehole to the inside of the borehole;

[0022] ⑤. Set the minimum opening of the electric control valve II to 15% of the maximum opening. When the flow-negative pressure sensor II shows that the methane concentration in the methane and air mixed gas is lower than 30%, the PLC integrated control platform controls the opening of the electric control valve II to decrease by 5% until the minimum opening is reached. After each opening adjustment, the monitoring and control subsystem uploads the monitoring data to the extraction management platform through the industrial ring network. The extraction management platform takes the maximum pure gas flow of the extraction main as the target and obtains the optimal opening of the electric control valve II through the built-in mathematical model.

[0023] ⑥. Set the minimum opening of the electric regulating valve III to 10% of the maximum opening. When the integrated monitoring instrument shows that the methane concentration in the extraction main pipe is lower than 30% and the electric regulating valve II is adjusted to the minimum opening and still cannot restore the gas concentration in the extraction main pipe to above 30%, the PLC integrated control platform controls the opening of the electric regulating valve III to decrease by 5% until the minimum opening is reached. After each opening adjustment, the monitoring and control subsystem uploads the monitoring data to the extraction management platform through the industrial ring network. The extraction management platform takes the maximum gas concentration of the extraction main pipe as the target and obtains the optimal opening of the electric regulating valve III through the built-in mathematical model.

[0024] ⑦. When the methane concentration in the extraction main pipe is between 16% and 30% and the opening of the electric regulating valve II and the electric regulating valve III cannot increase the methane concentration to 30%, the frequency converter is adjusted through the PLC integrated control platform to reduce the speed of the extraction pump. The reduction amplitude each time is 5% of the preset speed until the minimum speed is reached. After each speed adjustment, the monitoring and control subsystem uploads the monitoring data to the extraction management platform through the industrial ring network. The extraction management platform takes the maximum gas concentration of the extraction main pipe as the target and obtains the optimal extraction pump speed through the built-in mathematical model. The above mathematical models are all existing particle swarm optimization algorithms. By inputting the corresponding data into the particle swarm optimization algorithm, the optimal opening of the electric regulating valve II, the optimal opening of the electric regulating valve III and the optimal extraction pump speed can be obtained.

[0025] ⑧. When the gas concentration in the extraction main pipe is lower than 8%, the location of the extraction branch pipe with serious air leakage and low gas concentration is determined through the data of the flow-negative pressure sensor II of each extraction branch pipe and the comprehensive monitoring instruments of the extraction main pipe, and the electric regulating valves on the corresponding extraction branch pipe are closed through the PLC integrated control platform; when the electric regulating valves of all the extraction branch pipes are closed, the entire experimental process is completed.

[0026] Furthermore, if it is necessary to obtain the influence of gas extractability and air leakage degree of different coal seams on the adjustment of extraction parameters, the confining pressure pump is adjusted between steps ① and ② to apply different confining pressure loads to the core holder. The specific adjustment scheme is as follows:

[0027] a. When simulating gas extraction from boreholes in the original rock stress zone or stress concentration zone, the confining pressure applied by the confining pressure pumps of each extraction branch pipe is the same and kept constant;

[0028] b. When simulating gas extraction from boreholes in the pressure relief zone, the confining pressure pumps of each extraction branch pipe first apply confining pressure to the peak stress zone load, then gradually unload to a confining pressure value less than the stress in the original rock stress zone, and finally keep it constant;

[0029] c. When simulating gas extraction from boreholes in different stress zones, the confining pressure pump farthest from the extraction pump first increases the confining pressure to the peak stress of the coal sample and then unloads it to a certain pressure and keeps it constant. The two confining pressure pumps closest to the extraction pump apply the load of the original rock stress and keep it equal. The remaining confining pressure pumps apply the peak stress load and keep it constant.

[0030] d. When simulating the influence of mining stress on gas extraction during the mining process, the confining pressure pumps of each extraction branch pipe are all subjected to variable confining pressure loads. According to the duration of extraction, the load applied by each confining pressure pump is gradually increased from the original rock stress to the stress of the stress concentration area, and then gradually unloaded;

[0031] After the scheme is selected, the electric regulating valve I is opened to record the time when the flow-negative pressure sensor I on the extraction branch pipe displays the methane flow and negative pressure under different confining pressure load conditions. The flow-negative pressure sensor I has a methane detection and display function, that is, when methane reaches the flow-negative pressure sensor I and is detected by it, the flow-negative pressure sensor I starts to display the methane flow and negative pressure; if no methane is detected, the methane flow and negative pressure are not displayed; because different stress environments need to be simulated, when the stress environment is too large, it will cause the time for methane gas to break through the coal core in the core holder to be prolonged, so when the flow-negative pressure sensor I starts to display the methane flow and negative pressure, it indicates that methane flows into the extraction branch pipe through the core holder; by recording the time when the flow-negative pressure sensor I displays data under different confining pressure load conditions, the influence of different confining pressure stresses on gas extraction can be reflected.

[0032] Compared with the prior art, the present invention combines the main extraction pipe system, multiple extraction branch pipe subsystems, monitoring and adjustment subsystem, signal analysis and processing subsystem and extraction management platform. The main extraction pipe system and multiple extraction branch pipe subsystems cooperate with each other, which can effectively simulate the influence of coal seam gas extractability (i.e. different gas extraction conditions) and air leakage degree on the adjustment of extraction parameters. At the same time, the opening of each electric regulating valve and the speed of the extraction pump are adjusted by the signal analysis and processing subsystem and the monitoring and adjustment subsystem to achieve the adjustment of gas concentration and pure flow under different working conditions. The extraction management platform takes the maximum pure gas flow of the extraction pipe as the target, and obtains the optimal one by solving the built-in mathematical model. System operating parameters (including the optimal opening of different electric regulating valves and the optimal extraction pump speed); after obtaining the optimal valve opening and pump speed, the optimal parameters are continuously and dynamically obtained through the PLC integrated control platform. When a certain extraction branch pipe (i.e., the simulated gas extraction borehole) has serious air leakage and the gas extraction quality cannot be improved by adjusting the valve opening or the extraction pump speed, the extraction branch pipe can be automatically closed to realize the simulation of the later stage of extraction. This device and method can effectively simulate the flow of underground gas in the extraction system, clarify the relationship between system parameters and gas concentration and flow in the pipeline network, thereby providing data support for the intelligent adjustment of parameters of the underground extraction system to ensure a higher extraction concentration and relatively low energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0034] Figure 2 It is a structural schematic diagram of the drilling air leakage simulation device of the present invention;

[0035] Figure 3 It is a schematic diagram of stress distribution in front of the coal mining working face in the present invention.

[0036] In the figure: 1. gas pressure sensor, 2. methane storage tank, 3. extraction branch pipe, 4. core holder, 5. electric control valve I, 6. flow-negative pressure sensor I, 7. flow-negative pressure sensor II, 8. electric control valve II, 9. comprehensive monitoring instrument, 10. electric control valve III, 11. extraction pump, 12. extraction main pipe, 13. gas collection device, 14. frequency converter, 15. PLC integrated control platform, 16. power supply, 17. industrial ring network, 18. extraction management platform, 19. signal analyzer, 20. electric control valve IV, 21. methane gas cylinder, 22. gas supply pipe, 23. confining pressure pump, 24. electric control valve V, 25. crushed coal sample, 26-1. rectangular shell, 26-2. round hole, 27. temperature sensor, 28. signal processor. DETAILED DESCRIPTION

[0037] The present invention will be further described below.

[0038] like Figure 1 As shown, a gas extraction intelligent control experimental system includes an extraction branch pipe subsystem, an extraction main pipe system, a monitoring and control subsystem, a signal analysis and processing subsystem, an industrial ring network and an extraction management platform;

[0039] The extraction branch pipe subsystem includes a methane gas cylinder 21, a methane storage tank 2, a core clamp 4, a confining pressure pump 23 and a borehole air leakage simulation device. The methane gas cylinder 21 is connected to the inlet of the methane storage tank 2 to transport gas to the methane storage tank 2; a coal core is arranged in the core clamp 4, and the confining pressure pump 23 is connected to the core clamp 4 to enable the core clamp 4 to apply confining pressure to the coal core; the outlet of the methane storage tank 2 is connected to the extraction main system through the extraction branch pipe 3 and the core clamp 4, so as to transport gas into the core clamp 4 and transmit it to the extraction main system after passing through the coal core; Figure 2 As shown, the drilling air leakage simulation device includes a rectangular shell 26-1 and a crushed coal sample, the crushed coal sample is installed in the rectangular shell 26-1, a plurality of circular holes 26-2 are opened on one side of the rectangular shell 26-1, and the rectangular shell 26-1 is connected to the extraction branch pipe 3 through a pipeline, so that air enters the rectangular shell 26-1 through the circular holes 26-1, and is transported to the extraction branch pipe 3 after passing through the crushed coal sample; the plurality of circular holes are evenly distributed on one side of the rectangular shell 26-1. This arrangement can ensure that air evenly enters the rectangular shell 26-1 from different circular holes 26-2.

[0040] The extraction main system includes an extraction main 12, an extraction pump 11 and a gas collection device 13. The gas collection device 13 is connected to the extraction pump 11 through the extraction main 12. The extraction pump 11 is used to generate extraction negative pressure in the extraction main 12. The extraction main 12 is used to transport the gas transported by the extraction branch 3 to the gas collection device 13 for storage under the action of negative pressure. The extraction branch subsystem and the comprehensive monitoring instrument 9 are both multiple, and each comprehensive monitoring instrument 9 is respectively installed near the connection between each extraction branch subsystem and the extraction main 12. By setting multiple, gas extraction under different working conditions can be simulated, which is convenient for obtaining subsequent experimental data of corresponding working conditions.

[0041] The monitoring and control subsystem includes a gas pressure sensor 1, a flow-negative pressure sensor I6, a flow-negative pressure sensor II7, a comprehensive monitor 9, an electric regulating valve I5, an electric regulating valve II8, an electric regulating valve III10, an electric regulating valve IV20, an electric regulating valve V24, a frequency converter 14 and a PLC comprehensive control platform 15; the gas pressure sensor 1 is installed on the methane storage tank 2 to monitor the gas pressure inside the methane storage tank 2; the flow-negative pressure sensor I6 is installed between the core holder 4 and the drilling air leakage simulation device The flow-negative pressure sensor II7 is installed on the extraction branch pipe 3 between the drilling air leakage simulation device and the extraction main pipe 12, and is used to monitor the flow rate of the mixed gas of methane and air flowing into the drilling air leakage simulation device and the negative pressure at this position; the comprehensive monitoring instrument 9 is installed on the extraction main pipe 12, and is used to monitor the gas flow rate, methane concentration and negative pressure in the extraction main pipe 12; the electric regulating valve I5 is installed between the core holder 4 and the drilling air leakage simulation device The electric regulating valve Ⅱ8 is installed on the extraction branch pipe 3 between the drilling air leakage simulation device and the extraction main pipe 12 to control the flow of methane and air mixed gas entering the extraction main pipe 12; the electric regulating valve Ⅲ10 is installed on the extraction main pipe 12 to control the extraction gas flow of the extraction main pipe 12; the electric regulating valve Ⅳ20 is installed on the pipeline between the methane gas cylinder 21 and the methane storage tank 2 to control the methane flow injected into the methane storage tank 2; the electric regulating valve Ⅴ24 ... extraction branch pipe 3 between the drilling air leakage simulation device and the extraction main pipe 12 to control the flow of methane and air mixed gas entering the extraction main pipe 12; the electric regulating valve Ⅲ10 is installed on the extraction main pipe 12 to control the extraction gas flow of the extraction main pipe 12; the electric regulating valve Ⅳ20 is installed on the pipeline between the methane gas cylinder 21 and the methane storage tank 2 to control the methane flow injected into the methane storage tank 2 On the pipeline between the borehole air leakage simulation device and the extraction branch pipe 3, it is used to control the air leakage flow rate; the frequency converter 14 is connected to the extraction pump 11, and is used to adjust the rotation speed of the extraction pump 11; the PLC integrated control platform 15 receives the data fed back by the gas pressure sensor 1, the flow-negative pressure sensor I6, the flow-negative pressure sensor II7 and the integrated monitoring instrument 9, and adjusts the opening of the electric regulating valve I5, the electric regulating valve II8, the electric regulating valve III10, the electric regulating valve IV20 and the electric regulating valve V24 and the frequency converter 14;

[0042] The signal analysis and processing subsystem includes a temperature sensor 27, a signal processor 28 and a signal analyzer 19. The temperature sensor 27 is installed in a rectangular housing 26-1 and is used to monitor the real-time temperature value of the crushed coal sample and feed it back to the signal processor 28. The signal processor 28 processes the received signal and feeds it back to the signal analyzer 19.

[0043] The industrial ring network 17 is used to transmit the data of the PLC integrated control platform 15 to the extraction management platform 18;

[0044] The extraction management platform 18 is used to receive data from the industrial ring network 17 and the signal analyzer 19, and to achieve optimal parameter settings for the experimental system through data analysis and to display the feedback data in real time.

[0045] As an improvement of the present invention, the extraction main pipe 12 and the extraction branch pipe 3 are both stainless steel pipes. This material can effectively extend the service life of the pipeline and ensure the stability of the experiment. The extraction branch pipe 3 is threadedly connected to the extraction main pipe 12. This structure is easy to disassemble and install, and the connection is stable.

[0046] As another improvement of the present invention, the side of the rectangular shell 26-1 with the circular hole 26-2 is a detachable baffle, and the other sides are insulation plates. This structure makes it convenient to fill the crushed coal sample and reduces the loss of heat generated by the reaction between air and coal sample.

[0047] The working method of the above-mentioned gas extraction intelligent control experimental system has the following specific steps:

[0048] ① Turn on the power supply, close the electric regulating valve V24 through the PLC integrated control platform 15, open the electric regulating valve I5, the electric regulating valve II8, the electric regulating valve III10 and the electric regulating valve IV20 and keep them at the maximum opening, monitor the real-time pressure in the methane storage tank 2 through the gas pressure sensor 1, and temporarily close the electric regulating valve IV20 when the gas pressure in the methane storage tank 2 reaches the preset value;

[0049] According to the needs, the influence of gas extractability and air leakage degree of different coal seams on the adjustment of extraction parameters is obtained. Figure 3 As shown, it is necessary to adjust the confining pressure pump to apply different confining pressure loads to the core holder 4. The specific adjustment scheme is as follows:

[0050] a. When simulating gas extraction from boreholes in the original rock stress zone or stress concentration zone, the confining pressure pumps 23 of each extraction branch pipe 3 apply the same confining pressure and keep it constant;

[0051] b. When simulating gas extraction from boreholes in the pressure relief zone, the confining pressure pumps 23 of each extraction branch pipe 3 first apply confining pressure to the peak stress zone load, then gradually unload to a confining pressure value less than the stress in the original rock stress zone, and finally keep it constant;

[0052] c. When simulating gas extraction from boreholes in different stress zones, the confining pressure pump 23 farthest from the extraction pump 11 first increases the confining pressure to the peak stress of the coal sample and then unloads it to a certain pressure to keep it constant. The two confining pressure pumps 23 closest to the extraction pump 11 apply loads equal to the original rock stress, and the remaining confining pressure pumps 23 apply peak stress loads and keep them constant.

[0053] d. When simulating the influence of mining stress on gas extraction during the mining process, the confining pressure pumps 23 of each extraction branch pipe 3 apply a variable confining pressure load. According to the extraction time, the load applied by each confining pressure pump 23 gradually increases from the original rock stress to the stress of the stress concentration area, and then gradually unloads;

[0054] After the scheme is selected, the electric regulating valve I5 is opened to record the time when the flow-negative pressure sensor I6 on the extraction branch pipe 3 displays the methane flow and negative pressure under different confining pressure load conditions. The flow-negative pressure sensor I6 has a methane detection and display function, that is, when methane reaches the flow-negative pressure sensor I6 and is detected by it, the flow-negative pressure sensor I6 starts to display the methane flow and negative pressure; if no methane is detected, the methane flow and negative pressure are not displayed; because different stress environments need to be simulated, when the stress environment is too large, it will cause the time for methane gas to break through the coal core in the core holder 4 to be extended, so when the flow-negative pressure sensor I6 starts to display the methane flow and negative pressure, it indicates that methane flows into the extraction branch pipe 3 through the core holder 4; by recording the time when the flow-negative pressure sensor I6 displays data under different confining pressure load conditions, the influence of different confining pressure stresses on gas extraction can be reflected.

[0055] ②, when the flow-negative pressure sensor Ⅰ6 and the flow-negative pressure sensor Ⅱ7 detect that methane gas passes through the coal core in the core holder 4, the extraction pump 11 is turned on to work at a preset speed. During the extraction process, when the flow rate of the extraction main pipe 12 obtained by the integrated monitor 9 closest to the extraction pump 11 is the sum of the flow rates monitored by the flow-negative pressure sensors Ⅰ6 on each extraction branch pipe 3 and the methane concentrations monitored by each integrated monitor 9 are the same, it is considered that the system is airtight;

[0056] ③. Open the electric regulating valve IV20 to restore the gas pressure in the methane storage tank 2 to the preset value, and then adjust its opening to keep the gas pressure in the methane storage tank 2 at a constant preset value. The electric regulating valve I5 is controlled by the PLC integrated control platform 15 to continuously reduce the opening from the maximum opening of 100% by 5%, so as to realize the exponential attenuation of the gas flow over time;

[0057] ④. Fill the rectangular housing 26-1 with crushed coal samples, and control the electric regulating valve V24 to open to the maximum through the PLC integrated control platform 15, so as to simulate the air leakage from the crushed coal around the borehole to the inside of the borehole;

[0058] ⑤. Set the minimum opening of the electric regulating valve Ⅱ8 to 15% of the maximum opening. When the flow-negative pressure sensor Ⅱ7 shows that the methane concentration in the methane and air mixed gas is lower than 30%, the PLC integrated control platform 15 controls the opening of the electric regulating valve Ⅱ8 to reduce the opening by 5% until the minimum opening is reached. After each opening adjustment, the monitoring and control subsystem uploads the monitoring data to the extraction management platform 18 through the industrial ring network 17. The extraction management platform 18 takes the maximum pure gas flow of the extraction main 12 as the target and obtains the optimal opening of the electric regulating valve Ⅱ8 through the built-in mathematical model.

[0059] ⑥. Set the minimum opening of the electric regulating valve III10 to 10% of the maximum opening. When the integrated monitoring instrument 9 shows that the methane concentration in the extraction main pipe 12 is lower than 30% and the electric regulating valve II8 is adjusted to the minimum opening and still cannot restore the gas concentration in the extraction main pipe to above 30%, the PLC integrated control platform 15 controls the opening of the electric regulating valve III10 to decrease by 5% until the minimum opening is reached. After each opening adjustment, the monitoring and control subsystem uploads the monitoring data to the extraction management platform 18 through the industrial ring network 17. The extraction management platform 18 takes the maximum gas concentration of the extraction main pipe as the target and obtains the optimal opening of the electric regulating valve III10 through the built-in mathematical model.

[0060] ⑦. When the methane concentration in the extraction main pipe 12 is between 16% and 30% and the opening of the electric regulating valve Ⅱ8 and the electric regulating valve Ⅲ10 cannot increase the methane concentration to 30%, the frequency converter 14 is adjusted through the PLC integrated control platform 15 to reduce the speed of the extraction pump 11, and the amplitude of each reduction is 5% of the preset speed until the minimum speed is reached; after each speed adjustment, the monitoring and control subsystem uploads the monitoring data to the extraction management platform 18 through the industrial ring network 17. The extraction management platform 18 takes the maximum gas concentration of the extraction main pipe as the target and obtains the optimal extraction pump 11 speed through the built-in mathematical model; the above mathematical models are all existing particle swarm optimization algorithms. By inputting the corresponding data into the particle swarm optimization algorithm, the optimal opening of the electric regulating valve Ⅱ8, the optimal opening of the electric regulating valve Ⅲ10 and the optimal extraction pump 11 speed can be obtained;

[0061] ⑧. When the gas concentration in the extraction main pipe 12 is lower than 8%, the location of the extraction branch pipe 3 with serious air leakage and low gas concentration is determined through the data of the flow-negative pressure sensor Ⅱ7 of each extraction branch pipe 3 and each comprehensive monitoring instrument 9 of the extraction main pipe 12, and the electric regulating valves on the corresponding extraction branch pipe 3 are closed through the PLC comprehensive control platform 15; when the electric regulating valves of all the extraction branch pipes 3 are closed, the entire experimental process is completed.

[0062] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A gas extraction intelligent control experimental system, characterized in that: It includes extraction branch pipe subsystem, extraction main pipe system, monitoring and control subsystem, signal analysis and processing subsystem, industrial ring network and extraction management platform; The extraction branch pipe subsystem includes a methane gas cylinder, a methane storage tank, a core clamp, a confining pressure pump and a borehole air leakage simulation device. The methane gas cylinder is connected to the inlet of the methane storage tank for conveying gas to the methane storage tank; a coal core is arranged in the core clamp, and the confining pressure pump is connected to the core clamp for applying confining pressure to the coal core by the core clamp; the outlet of the methane storage tank is connected to the extraction main pipe system through the extraction branch pipe through the core clamp for conveying gas into the core clamp and transmitting it to the extraction main pipe system after passing through the coal core; the borehole air leakage simulation device includes a rectangular shell and a crushed coal sample, the crushed coal sample is installed in the rectangular shell, a plurality of circular holes are provided on one side of the rectangular shell, and the rectangular shell is connected to the extraction branch pipe through a pipeline for allowing air to enter the rectangular shell through the circular holes and be conveyed to the extraction branch pipe after flowing through the crushed coal sample; The extraction main pipe system includes an extraction main pipe, an extraction pump and a gas collection device. The gas collection device is connected to the extraction pump through the extraction main pipe. The extraction pump is used to generate extraction negative pressure in the extraction main pipe. The extraction main pipe is used to transport the gas transported by the extraction branch pipe to the gas collection device for storage under the action of negative pressure. The monitoring and control subsystem includes a gas pressure sensor, a flow-negative pressure sensor I, a flow-negative pressure sensor II, a comprehensive monitoring instrument, an electric regulating valve I, an electric regulating valve II, an electric regulating valve III, an electric regulating valve IV, an electric regulating valve V, a frequency converter and a PLC comprehensive control platform; the gas pressure sensor is installed on the methane storage tank to monitor the gas pressure inside the methane storage tank; the flow-negative pressure sensor I is installed on the extraction branch pipe between the core holder and the drilling air leakage simulation device to monitor the methane flow out of the core holder and the negative pressure at the location; the flow-negative pressure sensor II is installed on the extraction branch pipe between the drilling air leakage simulation device and the extraction main pipe to monitor the mixed gas flow of methane and air flowing into the drilling air leakage simulation device and the negative pressure at the location; the comprehensive monitoring instrument is installed on the extraction main pipe to monitor the gas flow, methane concentration and negative pressure in the extraction main pipe; the electric regulating valve I is installed between the core holder and the drilling air leakage simulation device. The electric regulating valve II is installed on the extraction branch pipe between the drilling air leakage simulation device and the extraction main pipe to control the flow of methane flowing out of the core clamp; the electric regulating valve II is installed on the extraction branch pipe between the drilling air leakage simulation device and the extraction main pipe to control the flow of methane and air mixed gas entering the extraction main pipe; the electric regulating valve III is installed on the extraction main pipe to control the extraction gas flow of the extraction main pipe; the electric regulating valve IV is installed on the pipeline between the methane gas cylinder and the methane storage tank to control the methane flow injected into the methane storage tank; the electric regulating valve V is installed on the pipeline between the drilling air leakage simulation device and the extraction branch pipe to control the leakage flow; the frequency converter is connected to the extraction pump to adjust the speed of the extraction pump; the PLC integrated control platform receives data fed back by the gas pressure sensor, the flow-negative pressure sensor I, the flow-negative pressure sensor II and the integrated monitoring instrument, and adjusts the opening of the electric regulating valve I, the electric regulating valve II, the electric regulating valve III, the electric regulating valve IV and the electric regulating valve V and the frequency converter; The signal analysis and processing subsystem includes a temperature sensor, a signal processor and a signal analyzer. The temperature sensor is installed in a rectangular housing and is used to monitor the real-time temperature value of the crushed coal sample and feed it back to the signal processor. The signal processor processes the received signal and feeds it back to the signal analyzer. The industrial ring network is used to transmit data from the PLC integrated control platform to the extraction management platform; The extraction management platform is used to receive data from the industrial ring network and signal analyzer, and achieve optimal parameter settings for the experimental system through data analysis and display the feedback data in real time.

2. The gas extraction intelligent control experimental system according to claim 1 is characterized in that: The main extraction pipe and the branch extraction pipe are both stainless steel pipes.

3. The gas extraction intelligent control experimental system according to claim 1 is characterized in that: The extraction branch pipe is threadedly connected to the extraction main pipe.

4. The gas extraction intelligent control experimental system according to claim 1 is characterized in that: The plurality of circular holes are evenly distributed on one side of the rectangular shell.

5. The gas extraction intelligent control experimental system according to claim 1 is characterized in that: The side of the rectangular shell with the circular hole is a detachable baffle, and the other sides are insulation boards.

6. The gas extraction intelligent control experimental system according to claim 1 is characterized in that: There are multiple extraction branch pipe subsystems and integrated monitoring instruments, and each integrated monitoring instrument is installed near the connection between each extraction branch pipe subsystem and the extraction main pipe.

7. A working method of the gas extraction intelligent control experimental system according to any one of claims 1 to 6, characterized in that: The specific steps are: ①. Turn on the power supply, close the electric regulating valve V through the PLC integrated control platform, open the electric regulating valves I, II, III and IV and keep them at the maximum opening, monitor the real-time pressure in the methane storage tank through the gas pressure sensor, and temporarily close the electric regulating valve IV when the gas pressure in the methane storage tank reaches the preset value; ② When the flow-negative pressure sensor I and the flow-negative pressure sensor II detect that methane gas passes through the coal core in the core holder, the extraction pump is turned on to work at a preset speed. During the extraction process, when the extraction main flow obtained by the integrated monitor closest to the extraction pump is the sum of the flow rates monitored by the flow-negative pressure sensors I on each extraction branch pipe and the methane concentrations monitored by each integrated monitor are the same, the system is considered to be airtight; ③. Open the electric regulating valve IV to restore the gas pressure in the methane storage tank to the preset value, and then adjust its opening to keep the gas pressure in the methane storage tank at a constant preset value. The electric regulating valve I is controlled by the PLC integrated control platform to continuously reduce the opening by 5% from the maximum opening, so as to realize the exponential attenuation of the gas flow over time; ④. Fill the rectangular shell with crushed coal samples, and control the electric regulating valve V to the maximum opening through the PLC integrated control platform to simulate the air leakage from the crushed coal around the borehole to the inside of the borehole; ⑤. Set the minimum opening of the electric control valve II to 15% of the maximum opening. When the flow-negative pressure sensor II shows that the methane concentration in the methane and air mixed gas is lower than 30%, the PLC integrated control platform controls the opening of the electric control valve II to decrease by 5% until the minimum opening is reached. After each opening adjustment, the monitoring and control subsystem uploads the monitoring data to the extraction management platform through the industrial ring network. The extraction management platform takes the maximum pure gas flow of the extraction main as the target and obtains the optimal opening of the electric control valve II through the built-in mathematical model. ⑥. Set the minimum opening of the electric regulating valve III to 10% of the maximum opening. When the integrated monitoring instrument shows that the methane concentration in the extraction main pipe is lower than 30% and the electric regulating valve II is adjusted to the minimum opening and still cannot restore the gas concentration in the extraction main pipe to above 30%, the PLC integrated control platform controls the opening of the electric regulating valve III to decrease by 5% until the minimum opening is reached. After each opening adjustment, the monitoring and control subsystem uploads the monitoring data to the extraction management platform through the industrial ring network. The extraction management platform takes the maximum gas concentration of the extraction main pipe as the target and obtains the optimal opening of the electric regulating valve III through the built-in mathematical model. ⑦. When the methane concentration in the extraction main pipe is between 16% and 30% and the opening of the electric regulating valve II and the electric regulating valve III cannot increase the methane concentration to 30%, the inverter is adjusted through the PLC integrated control platform to reduce the speed of the extraction pump. The reduction amplitude each time is 5% of the preset speed until the minimum speed is reached. After each speed adjustment, the monitoring and control subsystem uploads the monitoring data to the extraction management platform through the industrial ring network. The extraction management platform takes the maximum gas concentration of the extraction main pipe as the target and obtains the optimal extraction pump speed through the built-in mathematical model. ⑧. When the gas concentration in the extraction main pipe is lower than 8%, the location of the extraction branch pipe with serious air leakage and low gas concentration is determined through the data of the flow-negative pressure sensor II of each extraction branch pipe and the comprehensive monitoring instruments of the extraction main pipe, and the electric regulating valves on the corresponding extraction branch pipe are closed through the PLC integrated control platform; when the electric regulating valves of all the extraction branch pipes are closed, the entire experimental process is completed.

8. The working method of the gas extraction intelligent control experimental system according to claim 7 is characterized in that: If it is necessary to obtain the influence of gas extractability and air leakage degree of different coal seams on the adjustment of extraction parameters, then between steps ① and ②, add an adjustment confining pressure pump to apply different confining pressure loads to the core holder. The specific adjustment plan is as follows: a. When simulating gas extraction from boreholes in the original rock stress zone or stress concentration zone, the confining pressure applied by the confining pressure pumps of each extraction branch pipe is the same and kept constant; b. When simulating gas extraction from boreholes in the pressure relief zone, the confining pressure pumps of each extraction branch pipe first apply confining pressure to the peak stress zone load, then gradually unload to a confining pressure value less than the stress in the original rock stress zone, and finally keep it constant; c. When simulating gas extraction from boreholes in different stress zones, the confining pressure pump farthest from the extraction pump first increases the confining pressure to the peak stress of the coal sample and then unloads it to a certain pressure and keeps it constant. The two confining pressure pumps closest to the extraction pump apply the load of the original rock stress and keep it equal. The remaining confining pressure pumps apply the peak stress load and keep it constant. d. When simulating the influence of mining stress on gas extraction during the mining process, the confining pressure pumps of each extraction branch pipe are all subjected to variable confining pressure loads. According to the duration of extraction, the load applied by each confining pressure pump is gradually increased from the original rock stress to the stress of the stress concentration area, and then gradually unloaded; After the scheme is selected, open the electric regulating valve I and record the time when the flow-negative pressure sensor I on the extraction branch pipe displays the methane flow and negative pressure under different confining pressure load conditions.

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