An experimental device for low-rank coal seam gas development

Abstract

The application discloses an experimental device for low-rank coal seam gas development, and relates to the field of low-rank coal seam gas development, comprising: a gas storage tank for storing high-purity methane; a compressed gas pump arranged on the top of the gas storage tank, wherein the gas inlet end of the compressed gas pump is connected to the gas storage tank and is used for compressing the high-purity methane in the gas storage tank; and a simulation tank arranged on one side of the gas storage tank; wherein the output end of the compressed gas pump is connected with the gas inlet pipe between the simulation tank, and the simulation tank is connected with the gas outlet pipe between the gas storage tank; the device integrates high-pressure saturation, pressure regulation, mechanical crushing and gas recovery monitoring, realizes physical simulation of the whole process of low-rank coal seam gas coring, realizes closed recovery and accurate measurement of lost gas by combining with a flow monitoring meter for real-time measurement and accumulated gas emission.

Description

Technical Field

[0001] This invention relates to the field of low-rank coalbed methane development, specifically an experimental apparatus for low-rank coalbed methane development. Background Technology

[0002] Low-rank coalbed methane has a triple strategic significance in ensuring national energy security, reducing coal mine gas disasters, and reducing greenhouse gas emissions. It can form an important supplement to conventional natural gas, help achieve the "dual carbon" goal, and promote the coal industry's transformation to green energy.

[0003] In the development of coalbed methane in low-rank coal seams, the lost gas usually accounts for 12%–20% of the total gas content, which leads to the neglect or underestimation of the lost gas, resulting in a systematic bias in the assessment of coalbed methane resources. This, in turn, affects the judgment of development potential and the prediction of production capacity. The estimated value of the traditional USBM method is 8 to 16 times lower than the measured value, especially in low-rank coal seams and broken soft coal seams where the bias is more severe. Furthermore, it lacks the ability to recover and monitor the gas throughout the entire process of adsorbed methane desorption, making it difficult to meet the experimental requirements for accurate assessment of coalbed methane resources in low-rank coal seams.

[0004] Therefore, it is necessary to provide an experimental apparatus for the development of low-rank coalbed methane to solve the above-mentioned technical problems. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: an experimental apparatus for the development of low-rank coalbed methane, comprising:

[0006] Gas storage tanks are used to store high-purity methane;

[0007] A compressed air pump is installed on the top of the gas storage tank, and the air inlet of the compressed air pump is connected to the gas storage tank for compressing the high-purity methane inside the gas storage tank.

[0008] A simulation tank is placed on one side of the gas storage tank;

[0009] The output end of the compressed air pump is connected to the simulation tank via an air inlet pipe, and the simulation tank is connected to the air storage tank via an air outlet pipe.

[0010] Further, preferably, the simulated tank includes:

[0011] The outer tank has an air inlet and an air outlet on its outer wall for connecting the air inlet pipe and the air outlet pipe;

[0012] An inner tank, which is disposed inside the outer tank;

[0013] A feed sealing assembly is disposed on one side of the outer tank;

[0014] A positioning plate is fixedly installed on the other side of the outer tank;

[0015] A drive base is fixedly mounted on the inner tank near the positioning plate.

[0016] A drive assembly is disposed between the positioning disk and the drive base;

[0017] A spiral drill rod passes sequentially through the positioning plate, the drive assembly, and the drive seat, and the spiral drill rod is threadedly connected to the drive assembly and the drive seat.

[0018] Further, preferably, the inner tank includes:

[0019] Two fixing rings are fixedly installed on both sides of the inner tank along its axial direction;

[0020] Multiple striking plates are arranged in a circumferential array on the inner wall of the fixed ring, and each striking plate is connected between the fixed rings.

[0021] A coal sample mesh tube, which is disposed inside the fixing ring, is used to contain the coal sample;

[0022] Multiple ratchet rings are arranged in an axial array on the circumferential outer wall of the coal sample mesh cylinder;

[0023] The ratchet ring and the striking plate form a one-way meshing transmission structure, which is used to intermittently move the striking plate when the coal sample net cylinder rotates, so that it generates periodic vibration.

[0024] Further, preferably, the drive seat includes:

[0025] A base plate is disposed on the side of the drive seat near the positioning plate;

[0026] Top plate, which is located on the other side of the drive seat;

[0027] A threaded collar is fixedly embedded inside the top plate along the axis and penetrates the base plate; the spiral drill rod is threadedly engaged with the threaded collar.

[0028] The first toothed disc is rotatably sleeved on the outer wall of the threaded collar, and one end of the first toothed disc is connected to the output end of the drive assembly;

[0029] Multiple positioning posts are arranged in a circumferential array around the periphery of the first toothed disc and are fixedly connected between the base disc and the top disc;

[0030] Multiple second toothed discs, each second toothed disc being rotatably mounted on a corresponding positioning post, and the second toothed disc meshing with the first toothed disc;

[0031] An internal gear ring is rotatably disposed between the base disk and the top disk, and meshes with the second gear disk.

[0032] Furthermore, preferably, the fixing ring is fixedly connected to the inner wall of the outer tank, and one end of the coal sample mesh cylinder is fixedly connected to the inner toothed ring.

[0033] Furthermore, as a preferred embodiment, a safety valve and a flow meter are sequentially connected to the section of the vent pipe near the outer tank.

[0034] Further, preferably, the feed sealing assembly includes:

[0035] A flange ring seat is fixedly sleeved on the outside of the outer tank, and multiple positioning brackets are arrayed on the circumferential outer wall of the flange ring seat;

[0036] A sealing pin, which is rotatably mounted in the positioning frame;

[0037] A sealing cover is movably disposed at the end of the flange ring seat away from the outer tank, and the circumferential outer wall of the sealing cover is provided with a snap corresponding to the position of the positioning frame.

[0038] Furthermore, preferably, the flange ring seat is provided with a rotatable plunger for axially fixing and supporting the coal sample in the inner tank.

[0039] Compared with the prior art, the present invention provides an experimental apparatus for the development of low-rank coalbed methane, which has the following beneficial effects:

[0040] This device integrates high-pressure saturation, pressure regulation, mechanical crushing, and gas recovery monitoring to achieve physical simulation of the entire process of coring low-rank coalbed methane. Secondly, by using the reverse rotation of the auger drill rod in conjunction with the impact vibration of the cage-type mesh structure, coal dust blockage is continuously cleared to ensure the full desorption and escape of adsorbed methane. The pressure reduction process is precisely controlled by a safety valve according to a preset curve, and combined with the real-time measurement and cumulative escape volume of the flow meter, the lost gas is recovered and accurately measured in a closed manner.

[0041] In addition, the gas is returned to the storage tank throughout the process, avoiding resource waste and environmental pollution. This effectively solves the problems of underestimating gas loss and lacking full-process monitoring capabilities in the traditional USBM method, and provides a reliable experimental basis for the assessment and development potential judgment of low-rank coalbed methane resources. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of an experimental apparatus for the development of low-rank coalbed methane.

[0043] Figure 2 This is a schematic diagram of the cross-sectional structure of the simulated tank;

[0044] Figure 3 This is a schematic diagram of the cross-sectional structure of the drive disk;

[0045] Figure 4 This is a schematic diagram of the inner tank.

[0046] Figure 5 for Figure 2 A magnified schematic diagram of the structure at point A in the middle.

[0047] In the diagram: 1. Gas storage tank; 2. Simulation tank; 21. Outer tank; 211. Air inlet; 212. Air outlet; 22. Inner tank; 221. Fixing ring; 222. Striking plate; 223. Coal sample mesh tube; 224. Ratchet ring; 23. Feed sealing assembly; 231. Flange ring seat; 232. Sealing cover plate; 233. Sealing pin; 234. Positioning frame; 235. Bayonet; 24. Drive seat; 241. Base plate; 242. Top plate; 243. Threaded collar; 244. First gear plate; 245. Second gear plate; 246. Positioning column; 247. Internal gear ring; 25. Drive assembly; 26. Spiral drill rod; 27. Positioning plate; 3. Compressed air pump; 4. Air inlet pipe; 5. Air outlet pipe; 6. Flow meter; 7. Safety valve. Detailed Implementation

[0048] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a distinguishing method used to describe objects with the same attributes in the embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of elements is not necessarily limited to those elements but may include other elements not explicitly listed or inherent to those processes, methods, products, or apparatuses.

[0049] Example: Please refer to Figures 1-5 In this embodiment of the invention, an experimental apparatus for the development of low-rank coalbed methane is provided, comprising:

[0050] Gas storage tank 1, used to store high-purity methane;

[0051] A compressed air pump 3 is installed on the top of the gas storage tank 1, and the air inlet of the compressed air pump 3 is connected to the gas storage tank 1 for compressing the high-purity methane inside the gas storage tank 1.

[0052] Simulation tank 2 is placed on one side of the gas storage tank 1;

[0053] The output end of the compressed air pump 3 is connected to the simulation tank 2 by an air inlet pipe 4, and the simulation tank 2 is connected to the air storage tank 1 by an air outlet pipe 5.

[0054] In the development of low-lying coalbed methane, lost gas typically accounts for 12%–20% of the total gas content. If this portion of gas is ignored or underestimated, it will lead to a systematic bias in the assessment of coalbed methane resources, thereby affecting the judgment of development potential and production capacity prediction. This device, by recreating the actual process of "coring → drilling → exposure → tank filling" on site, can directly collect and measure lost gas. The specific experimental operation is divided into the following five stages:

[0055] Phase 1: Coal sample preparation and loading. Low-rank coal columns are collected on-site and their ends are cut flat to prevent stress concentration from causing the coal column to crack. Then, the prepared coal sample is loaded into simulation tank 2 and axially fixed by a plunger to ensure that the coal sample does not shift during subsequent experiments. Finally, simulation tank 2 is sealed and closed by the feed sealing assembly 23, ready to enter the next phase.

[0056] Second stage: High pressure saturation. Start the compressed air pump 3 and inject compressed air into the simulation tank 2 to conduct a leak test. If the seal meets the standard, fill the simulation tank 2 with high-purity methane. When the pressure inside the tank reaches the preset threshold (about 8 MPa), let the simulation tank 2 stand for more than 48 hours to ensure that the coal sample fully adsorbs methane to a saturated state, thereby truly simulating the adsorption equilibrium state under in-situ conditions of the coal seam.

[0057] The third stage: venting free gas, opening safety valve 7, and gradually reducing the pressure in simulation tank 2 according to the preset pressure reduction curve, usually from 8 MPa to atmospheric pressure 0.1 MPa; during this process, the free gas in the pores of the coal sample is discharged and flows back into the gas storage tank 1 along the gas outlet pipe 5, realizing the recovery and utilization of gas. In order to further remove residual methane in the pipeline, nitrogen can be selectively introduced to purge the gas outlet pipeline; after this stage, only adsorbed methane remains in the coal sample.

[0058] Fourth stage: Crushing and depressurization. Start the drive component 25 to drive the auger drill rod 26 to mechanically crush the coal sample in the simulation tank 2. At the same time, adjust the safety valve 7 according to the preset pressure control curve P(t) to make the pressure in the tank decrease synchronously with the crushing process, so as to simulate the desorption behavior of coalbed methane during the depressurization process.

[0059] Fifth stage: Gas collection and monitoring. As the coal sample is continuously crushed and the pressure inside the tank gradually decreases, the adsorbed methane is gradually desorbed and escapes. After the desorbed gas is stabilized by the safety valve 7, the instantaneous flow rate and cumulative flow rate are measured in real time by the flow meter 6. The cumulative escape amount is the total amount of lost gas. All the desorbed gas also flows back into the gas storage tank 1 through the gas outlet pipeline, realizing the closed recovery and measurement of gas throughout the entire process.

[0060] It should be noted that from the beginning of the high-pressure saturation stage until the end of the experiment, the pressure in the simulation tank 2 is always greater than the pressure in the gas storage tank 1. By maintaining this positive pressure gradient, it is ensured that the free gas discharged from the simulation tank 2 and the loss gas generated by desorption can flow back into the gas storage tank 1 smoothly along the gas outlet pipe 5, without the need to add an additional gas delivery pump, thus achieving passive, continuous and stable gas recovery.

[0061] In this embodiment, refer to the appendix. Figure 2 The simulated tank 2 includes:

[0062] The outer tank 21 has an air inlet 211 and an air outlet 212 on its outer wall for connecting the air inlet pipe 4 and the air outlet pipe 5.

[0063] Inner tank 22, which is disposed inside the outer tank 21;

[0064] The feed sealing assembly 23 is disposed on one side of the outer tank 21 and is used to fill the coal sample into the inner tank 22 and seal the inner tank 22.

[0065] Positioning plate 27 is fixedly disposed on the other side of the outer tank 21;

[0066] The drive seat 24 is fixedly disposed on the inner tank 22 near the positioning plate 27;

[0067] A drive assembly 25, disposed between the positioning disk 27 and the drive seat 24, is used to provide rotary drilling power;

[0068] The auger drill rod 26 passes sequentially through the positioning plate 27, the drive assembly 25, and the drive seat 24, and the auger drill rod 26 is threadedly connected to the drive assembly 25 and the drive seat 24.

[0069] When the feed sealing assembly 23 is closed, the feed sealing assembly 23, the outer tank 21, the drive seat 24 and the spiral drill rod 26 together form a sealed chamber. This chamber remains sealed throughout the experiment to prevent gas leakage and ensure the accuracy of the loss gas measurement.

[0070] After the coal sample is prepared, it is placed into the inner tank 22. During loading, one end of the coal sample is pushed against the drive seat 24, and then the feed sealing assembly 23 is closed. At this time, the feed sealing assembly 23 locks and pushes the coal sample from the other end, working together with the drive seat 24 to fix the two ends of the coal sample axially. This fixing method can ensure that the coal sample remains stable during the subsequent high-pressure saturation, depressurization and crushing process, and does not undergo axial movement or displacement.

[0071] When it is necessary to crush the coal sample, the auger drill rod 26 rotates axially under the drive of the drive assembly 25 to gradually crush the coal sample in the inner tank 22. Throughout the crushing process, the sealed chamber remains sealed to ensure that the desorbed gas cannot leak out, thereby achieving complete collection and measurement of the lost gas.

[0072] It should be noted that the drive assembly 25 uses a through-type lead screw stepper motor. This type of motor can provide precise rotation and linear feed, which facilitates the precise adjustment of the drilling speed and drilling depth of the auger drill rod 26, thereby improving the repeatability of the experiment and the reliability of the data.

[0073] Further, see attached document. Figure 4 The inner tank 22 includes:

[0074] Two fixing rings 221 are fixedly disposed on both axial sides of the inner tank 22;

[0075] Multiple striking plates 222 are arranged in a circumferential array on the inner wall of the fixing ring 221, and each striking plate 222 is connected between the fixing rings 221 to form a cage-like support structure.

[0076] A coal sample net cylinder 223 is disposed inside the fixing ring 221 to hold the coal sample. The cylinder wall of the coal sample net cylinder 223 has a mesh structure to facilitate the discharge of coal powder during the crushing process.

[0077] Multiple ratchet rings 224 are arranged in an axial array on the circumferential outer wall of the coal sample net cylinder 223;

[0078] The ratchet ring 224 and the striking plate 222 form a one-way meshing transmission structure. When the coal sample tube 223 rotates in a specific direction, the ratchet ring 224 intermittently pushes the striking plate 222, causing the striking plate 222 to vibrate periodically. When the coal sample tube 223 rotates in the opposite direction, the ratchet ring 224 and the striking plate 222 are in a relative sliding state and no pushing effect is produced. This one-way transmission characteristic makes the striking vibration only triggered in a specific rotation direction. When vibration is not required, the rotation direction of the drive component 25 can be changed to make the coal sample tube 223 rotate smoothly.

[0079] When crushing the coal sample, the drive seat 24 drives the coal sample mesh cylinder 223 to rotate in the first direction. At the same time, the auger drill rod 26 rotates and drills in the opposite direction, i.e., the second direction, driven by the drive assembly 25. This creates a counter-rotational engagement between the mesh cylinder and the drill rod. The counter-rotation generates stronger relative shearing and friction between the drill rod and the coal sample, accelerating the crushing and stripping of the coal sample and reducing drilling resistance.

[0080] During the crushing process, coal samples continuously detach to form coal powder. Due to the mesh structure of the coal sample mesh cylinder 223, the coal powder can be discharged outward through the mesh openings. At the same time, the striking plate 222 generates periodic vibrations under the intermittent prying of the ratchet ring 224, continuously striking the outer wall of the coal sample mesh cylinder 223, causing the coal powder adhering to the mesh openings and coal sample pores to be shaken off in time, preventing pore blockage. Through the combined effect of striking vibration and mesh cylinder rotation, the coal powder in the pores inside the coal sample is removed in time, which helps the desorbed gas to escape smoothly, thereby improving the accuracy of loss gas measurement.

[0081] It should be noted that a filter screen is installed at the vent 212 of the outer tank 21 to prevent free gas and loss gas generated during desorption from carrying coal dust into the vent pipe. In addition, a collection trough is opened at the bottom of the inner wall of the outer tank 21 to collect the coal dust discharged from the mesh of the coal sample mesh cylinder 223 during crushing and vibration. The collection trough is located at the lowest point of the inner wall of the outer tank 21. Utilizing the principle of natural settling due to gravity, the detached coal dust falls into the collection trough along the inner wall, which is convenient for centralized cleaning and weighing analysis after the experiment. By weighing the coal dust in the collection trough, the degree of crushing of the coal sample and the coal dust yield can be further evaluated, providing supplementary data support for the study of the desorption characteristics of low coal seam gas.

[0082] Furthermore, in this embodiment, reference is made to the appendix. Figure 3 The drive seat 24 includes:

[0083] A base plate 241 is disposed on the side of the drive seat 24 near the positioning plate 27;

[0084] Top plate 242, which is disposed on the other side of the drive seat 24;

[0085] A threaded collar 243 is fixedly embedded in the top plate 242 along the axis and penetrates the base plate 241. The spiral drill rod 26 is threadedly engaged with the threaded collar 243.

[0086] The first toothed disc 244 is rotatably sleeved on the outer wall of the threaded collar 243, and one end of the first toothed disc 244 is connected to the output end of the drive assembly 25 for directly receiving the rotational power transmitted by the drive assembly 25.

[0087] Multiple positioning posts 246 are arranged in a circumferential array around the first gear disk 244 and are fixedly connected between the base disk 241 and the top disk 242, serving as mounting brackets for gear transmission.

[0088] Multiple second toothed discs 245 are rotatably mounted on the corresponding positioning post 246, and the second toothed discs 245 mesh with the first toothed disc 244 to transmit power as idler wheels;

[0089] The internal gear ring 247 is rotatably disposed between the base plate 241 and the top plate 242, and meshes with the second gear plate 245, serving as the power output end.

[0090] When the drive assembly 25 drives the auger drill rod 26 to rotate and drill, it synchronously drives the first toothed disc 244 to rotate. Under the transmission of the second toothed disc 245, the inner toothed ring 247 rotates, and the direction of rotation is opposite to that of the first toothed disc 244. Since the first toothed disc 244 and the auger drill rod 26 have the same direction of rotation, the inner toothed ring 247 and the auger drill rod 26 have opposite directions of rotation.

[0091] It should be noted that the reference appendix... Figure 5 The fixing ring 221 is fixedly connected to the inner wall of the outer tank 21, and one end of the coal sample net cylinder 223 is fixedly connected to the inner toothed ring 247.

[0092] Therefore, when the internal toothed ring 247 drives the coal sample mesh cylinder 223 to rotate, the ratchet ring 224 set on the outer wall of the coal sample mesh cylinder 223 rotates together. Since the ratchet ring 224 and the stationary striking plate 222 form a one-way meshing transmission structure, during the rotation of the coal sample mesh cylinder 223, the ratchet ring 224 intermittently pushes the striking plate 222, causing it to produce periodic elastic deformation and rebound, thereby continuously striking the outer wall of the coal sample mesh cylinder 223, causing the coal powder attached to the coal sample pores and mesh holes to be shaken off in time and discharged from the mesh holes.

[0093] In this embodiment, a safety valve 7 and a flow meter 6 are sequentially connected to a section of the gas outlet pipe 5 near the outer tank 21. The safety valve 7 is used to control the outlet pressure of the simulation tank 2, and the flow meter 6 is used to measure the instantaneous flow rate and cumulative flow rate of the desorbed gas, thereby accurately measuring the total amount of lost gas.

[0094] It should be noted that the safety valve 7 is normally closed in the initial state. Its working principle is as follows: by actively depressurizing, it controls and maintains the pressure upstream (i.e., the side of the simulation tank 2) so that it changes in stages according to the preset experimental curve. The safety valve 7 will automatically open to depressurize when the pressure inside the tank exceeds the set threshold, or will actively open under the action of an external control signal to achieve precise pressure regulation.

[0095] During the high-pressure saturation stage, the pressure threshold of safety valve 7 is set to 8 MPa. At this time, safety valve 7 is in the closed state, and the internal pressure of simulation tank 2 gradually increases to 8 MPa. It is then left to stand at this pressure for more than 48 hours to achieve saturation. Since the threshold of safety valve 7 is set to 8 MPa, when the pressure inside the tank reaches this value, safety valve 7 remains closed to prevent gas leakage and ensure that the coal sample fully adsorbs methane under constant high pressure. During the free gas venting stage, safety valve 7 is gradually opened, so that the pressure inside simulation tank 2 decreases from 8 MPa to 0.1 MPa (normal pressure) according to the preset pressure reduction curve. During this process, free methane (free gas) in the pores of the coal sample is discharged as the pressure decreases and flows back into the gas storage tank 1 through the gas outlet pipe 5. During the crushing and depressurization stage, safety valve 7 is dynamically adjusted according to the P(t) curve, so that the pressure inside simulation tank 2 decreases according to the preset curve. The loss gas generated by desorption is discharged through safety valve 7, and the instantaneous flow rate and cumulative flow rate are measured in real time by flow meter 6.

[0096] Further, see attached document. Figure 2 The feed sealing assembly 23 includes:

[0097] A flange ring seat 231 is fixedly sleeved on the outside of the outer tank 21, and a plurality of positioning brackets 234 are arrayed on the outer wall of the flange ring seat 231 around its periphery;

[0098] A sealing pin 233 is rotatably mounted in the positioning frame 234;

[0099] A sealing cover plate 232 is movably disposed at one end of the flange ring seat 231 away from the outer tank 21, and the circumferential outer wall of the sealing cover plate 232 is provided with a slot 235 corresponding to the position of the positioning frame 234.

[0100] It should be noted that the flange ring seat 231 is provided with a rotatable plunger, which is used to fix and support the coal sample in the inner tank 22 in the axial direction, so as to ensure that the coal sample maintains a stable axial position during high pressure saturation, depressurization and crushing stages.

[0101] After loading the coal sample into the coal sample mesh cylinder 223, first adjust the plunger inside the flange ring seat 231 to push the coal sample from one axial end to make it tightly fixed inside the coal sample mesh cylinder 223, preventing axial movement during the experiment; then cover the sealing cover plate 232 onto the flange ring seat 231, and align the slots 235 on the outer circumferential wall of the sealing cover plate 232 with the positions of the positioning frames 234 on the flange ring seat 231; finally, insert the sealing pin 233, which is rotatably set in the positioning frame 234, into the corresponding slots 235 and apply pressure to rotate and lock it, so that the sealing cover plate 232 and the flange ring seat 231 form a tight fit through compression, thereby achieving overall sealing of the simulation tank 2.

[0102] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An experimental apparatus for the development of low-rank coalbed methane, characterized in that, include: Gas storage tank (1) is used to store high-purity methane; A compressed air pump (3) is installed on the top of the gas storage tank (1). The air inlet of the compressed air pump (3) is connected to the gas storage tank (1) and is used to compress the high-purity methane inside the gas storage tank (1). A simulation tank (2) is placed on one side of the gas storage tank (1); The output end of the compressed air pump (3) is connected to the simulation tank (2) by an air inlet pipe (4), and the simulation tank (2) is connected to the air storage tank (1) by an air outlet pipe (5).

2. The experimental apparatus for developing low-rank coalbed methane according to claim 1, characterized in that, The simulated tank (2) includes: The outer tank (21) has an air inlet (211) and an air outlet (212) on its outer wall for connecting the air inlet pipe (4) and the air outlet pipe (5). Inner tank (22), which is disposed inside the outer tank (21); A feed sealing assembly (23) is disposed on one side of the outer tank (21); Positioning plate (27), which is fixedly installed on the other side of the outer tank (21); A drive seat (24) is fixedly disposed on the inner tank (22) near the positioning plate (27); A drive assembly (25) is disposed between the positioning disk (27) and the drive seat (24); The auger drill rod (26) passes sequentially through the positioning plate (27), the drive assembly (25) and the drive seat (24), and the auger drill rod (26) is threadedly connected to the drive assembly (25) and the drive seat (24).

3. The experimental apparatus for developing low-rank coalbed methane according to claim 2, characterized in that, The inner tank (22) includes: Two fixing rings (221) are fixedly installed on both sides of the inner tank (22) along the axial direction; Multiple striking plates (222) are arranged in a circumferential array on the inner wall of the fixed ring (221), and each striking plate (222) is connected between the fixed rings (221). A coal sample net tube (223) is disposed inside the fixing ring (221) to hold the coal sample; Multiple ratchet rings (224) are arranged in an axial array on the circumferential outer wall of the coal sample net cylinder (223); The ratchet ring (224) and the striking plate (222) form a one-way meshing transmission structure, which is used to intermittently poke the striking plate (222) when the coal sample net cylinder (223) rotates, so that it generates periodic vibration.

4. An experimental apparatus for developing low-rank coalbed methane according to claim 3, characterized in that, The drive unit (24) includes: A base plate (241) is disposed on the side of the drive seat (24) near the positioning plate (27); Top plate (242), which is located on the other side of the drive seat (24); A threaded collar (243) is fixedly embedded in the top plate (242) along the axis and penetrates the base plate (241). The spiral drill rod (26) is threadedly engaged with the threaded collar (243). The first gear disc (244) is rotatably sleeved on the outer wall of the threaded collar (243), and one end of the first gear disc (244) is connected to the output end of the drive assembly (25); Multiple positioning posts (246) are arranged in a circumferential array around the first toothed disc (244) and are fixedly connected between the base disc (241) and the top disc (242); Multiple second toothed discs (245) are rotatably mounted on the corresponding positioning post (246), and the second toothed disc (245) meshes with the first toothed disc (244); An internal gear ring (247) is rotatably disposed between the base plate (241) and the top plate (242), and meshes with the second gear plate (245).

5. An experimental apparatus for developing low-rank coalbed methane according to claim 4, characterized in that, The fixing ring (221) is fixedly connected to the inner wall of the outer tank (21), and one end of the coal sample net cylinder (223) is fixedly connected to the inner toothed ring (247).

6. An experimental apparatus for developing low-rank coalbed methane according to claim 2, characterized in that, The section of the vent pipe (5) near the outer tank (21) is connected in sequence to a safety valve (7) and a flow meter (6).

7. An experimental apparatus for developing low-rank coalbed methane according to claim 2, characterized in that, The feed sealing assembly (23) includes: A flange ring seat (231) is fixedly sleeved on the outside of the outer tank (21), and a plurality of positioning frames (234) are arranged on the circumferential outer wall of the flange ring seat (231). A sealing pin (233) is rotatably mounted in the positioning frame (234); A sealing cover (232) is movably disposed at one end of the flange ring seat (231) away from the outer tank (21), and the circumferential outer wall of the sealing cover (232) is provided with a slot (235) corresponding to the position of the positioning frame (234).

8. An experimental apparatus for developing low-rank coalbed methane according to claim 7, characterized in that, The flange ring seat (231) is provided with a rotatable plunger for fixing and supporting the coal sample in the inner tank (22) in the axial direction.

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