Coal seam gas control method based on hydrothermal activation type adsorption capsules

Abstract

The invention discloses a coal seam gas control method based on hydrothermal activation type adsorption capsules, and belongs to the technical field of coal mine gas control and coal seam gas extraction. Comprising the following steps: preparing a hydrothermal activation type adsorption capsule from a double-layer capsule outer membrane and an adsorbent complex, and designing the shell wall thickness of a capsule inner membrane according to target activation time and the dissolution rate of a shell material; the adsorption capsule is delivered to the target coal seam hole section in a delivery mode; underground water in a target coal seam permeates and dissolves the capsule outer membrane and the capsule inner membrane, so that a large number of water molecules and CaO particles are subjected to a violent exothermic reaction to release heat, and a large number of methane molecules in an adsorption state are driven to be desorbed from a coal matrix; desorbed high-concentration methane molecules are rapidly captured and fixed through active carbon particles. According to the method, accurate targeted treatment of the gas is achieved by accurately feeding the adsorption capsules, the desorption rate and the total amount of the gas are remarkably increased through a CaO particle exothermic reaction, and passive adsorption is changed into active displacement-adsorption.

Description

Technical Field

[0001] This invention relates to a method for preventing and controlling coalbed methane, specifically a method for preventing and controlling coalbed methane based on hydrothermal activated adsorption capsules, belonging to the technical field of coal mine gas control and coalbed methane extraction. Background Technology

[0002] Methane, the main component of coal mine gas, is not only a major cause of coal and gas outbursts and gas explosions during underground coal mining, but also a clean energy source with abundant reserves. Therefore, the efficient management and extraction of coal mine gas is a core issue concerning safe production and energy conservation and emission reduction. Currently, pre-extraction through underground drilling is the fundamental measure for gas control. However, for the low-permeability, high-adsorption coal seams commonly found in my country, conventional drilling extraction is extremely inefficient. The fundamental reason is that a large amount of gas exists in an adsorbed state within the microporous fracture system of the coal seam, making effective desorption and flow to the borehole through the fracture network difficult.

[0003] To overcome this challenge, various enhanced extraction methods have been proposed in existing technologies and research. In order to actively drive gas desorption, the industry has explored various physical field excitation methods, but all of them have limitations to varying degrees: 1) For example, Chinese patent application publication number CN109184653A discloses a hydraulic fracturing / cutting method that increases the permeability of coal seams by creating fractures with high-pressure water; however, this method consumes a large amount of water, may damage the stability of the surrounding rock, and has limited microscopic effects on the coal matrix. 2) For example, Chinese patent application CN120652568A discloses a microwave / thermal excitation method that promotes desorption by heating coal and utilizing the characteristic that the amount of gas adsorption decreases with increasing temperature. However, existing technologies (such as downhole resistance heating and electromagnetic heating) have problems such as high energy loss, uncontrollable heating range, complex equipment, high cost, and safety hazards, making it difficult to apply on a large scale in dispersed boreholes. 3) In addition, some studies have attempted to inject surfactants or chemical reactants into coal seams to change the properties of the coal or directly replace gas, such as the patents with publication numbers CN120636570A and CN120556966A; however, such chemical agents may cause groundwater pollution, and their reaction process and long-term environmental impact are difficult to assess, resulting in high application risks.

[0004] Therefore, there is an urgent need to design a gas control solution that can combine the following advantages: it can be accurately delivered to the dangerous areas deep in the borehole; its adsorption effect can be activated "on demand" in a controllable manner; and it can provide a safe, built-in driving force to actively and efficiently promote the desorption of gas from the coal seam. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of existing borehole gas adsorption materials being unable to target deep areas, having uncontrollable adsorption initiation, and lacking the ability to actively drive gas desorption. The invention provides a method for coal seam gas control based on hydrothermal activated adsorption capsules, which can achieve directional delivery, controllable activation, and use its own reaction heat to drive gas desorption.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a method for coalbed methane control based on hydrothermal activated adsorption capsules, comprising the following steps: S1. Preparation of hydrothermally activated adsorption capsules: A hollow capsule outer membrane was formed using a water-soluble polymer material through molding. A hollow capsule inner membrane was formed using a material with a high water permeability rate through molding. In a dry environment, an adsorbent composite was filled and sealed within the double-layer hollow shell structure. The adsorbent composite included activated carbon particles filled and sealed within the hollow structure inside the inner capsule membrane. The inner capsule membrane was then placed inside the outer capsule membrane. The adsorbent composite also included CaO particles filled and sealed between the outer and inner capsule membranes, with a mass ratio of CaO particles to activated carbon particles of 1:3. The final adsorbent capsule was thus prepared. Sa1, based on the target activation time t a and the dissolution rate v of the shell structure material d Design the wall thickness d of the capsule inner membrane: The formula for calculating wall thickness d is: d = v d ×t a In the formula, the dissolution rate v d It refers to the reduction in thickness of the outer shell structure material per unit time in a simulated coal seam water environment, and its value is determined in advance through a standard immersion test; Dissolution rate v d The defined formula is: v d = (d1-d0) / (t1-t0), where the dissolution rate v d The unit is m⋅s -1 d1 is the thickness of the capsule inner membrane after dissolution, in meters; d0 is the initial thickness of the capsule inner membrane, in meters; t1 is the time after dissolution, in seconds; t0 is the initial time, in seconds. Sb1. Calculate the required mass of activated carbon particles based on the amount of gas desorbed from the heat generated by CaO particles: 1) Estimate the maximum water volume obtainable from a single hydrothermally activated adsorption capsule: Assuming that after activation by the hydrothermal activated adsorption capsule, the coal body that can be effectively heated and draw water from it is a spherical region centered on it, the maximum water volume... m water The calculation formula is: m water =V coal×ρ×w, where ρ is the density of the coal seam, w is the moisture content of the coal seam, and V coal V is the volume of the coal body. coal =4 / 3πr 3 r is the effective radius of the capsule for water absorption; 2) Calculate the mass of CaO that can be reacted with the maximum amount of water: Based on the chemical reaction equation: CaO + H2O → Ca(OH)2, the mass ratio of the two reactants is calculated: 56g CaO reacts with 18g H2O, meaning that 3.11g of CaO is needed to completely react with 1g of water. Therefore, the maximum mass of CaO that the maximum water volume can support is: m CaO =m water ×56 / 18; 3) Calculate the heat generated by CaO and estimate the amount of gas that can be desorbed: The total heat released by CaO is Q total Q total =m CaO / 56×64, Considering a thermal efficiency of 0.4, the amount of gas that can be desorbed, M CH4 For: M CH4 =Q total ×0.4 / H desorption In the formula, H desorption To desiccate endothermic; 4) Calculate the required mass of activated carbon based on the amount of gas that can be desorbed: The required activated carbon mass mAC is: mAC = M CH4 / Cac, where Cac is the adsorption capacity, and 1g of activated carbon corresponds to 0.15g of adsorbed methane. S2. Deploy the adsorption capsule into the extraction borehole: A capsule fixing shaft is provided on the outer end of the adsorption capsule. At the same time, a capsule conveying device is prepared. The capsule conveying device includes a capsule conveying rod. The capsule conveying rod is hollow inside and has a rectangular opening structure at one end. The upper and lower inner walls of the outer end of the rectangular opening are connected by springs. The two spring clips are inclined from the outside of the rod to the center of the rod when there is no tension or pressure. A spring pull rope is also provided inside the capsule conveying rod. The spring pull rope is divided into two strands at the rectangular opening structure. Each strand passes around the pull rope deflector and is fixedly connected to the inner wall surface of the spring clip. The adsorption capsule is clamped and fixed between the two spring clips by pushing the capsule fixing shaft, and then fixed on the capsule conveying rod. After the extraction borehole is completed underground, the capsule delivery rod with the adsorption capsule is placed inside the extraction borehole. The capsule delivery rod is pushed to deliver the capsule to the target coal seam section. After the adsorption capsule reaches the designated position, the spring rope is pulled. At this time, the spring rope passes around the pull rope deflector and pulls the spring clamp, which in turn causes the two spring clamps to move up and down respectively to release the capsule fixing shaft, thus completing the delivery of the adsorption capsule. S3, Hydrothermal reaction activates adsorption capsules: S31. Moisture Infiltration and Activation: After the adsorption capsule is delivered to the target coal seam, the groundwater in the target coal seam first infiltrates and dissolves the outer membrane of the capsule in the form of water molecules, and then contacts the inner membrane of the capsule and causes it to dissolve rapidly. This process occurs within the target activation time t. a Completed within the time limit; S32. Shell rupture: After the inner membrane of the capsule dissolves, the CaO particles inside it begin to come into contact with water molecules and react initially to generate gas and stress, resulting in a gap in the outer membrane of the capsule. S33. Hydrothermal reaction driven: Water molecules rush in in large quantities through the gap in the outer membrane of the capsule and react violently with CaO particles to release heat. During this reaction, the local coal temperature around the adsorption capsule rises rapidly to 60°C~120°C. This heat reduces the adsorption energy of gas on the target coal seam, thereby actively driving the adsorbed methane molecules to desorb in large quantities from the coal matrix. S4. Adsorption and capture of gas: Driven by the concentration and pressure differences, the desorbed high-concentration methane molecules migrate toward the capsule and are rapidly captured and fixed by the activated carbon particles exposed by the ruptured outer shell, thus completing the adsorption of methane.

[0007] In step S1, the wall thickness d of the capsule inner membrane is related to the moisture content of the coal seam. When the moisture content of the coal seam is >15%, the wall thickness is designed to be 4 mm; when the moisture content of the coal seam is 10%, the wall thickness is designed to be 3 mm; when the moisture content of the coal seam is 5%, the wall thickness is designed to be 2 mm; when the moisture content of the coal seam is 2%, the wall thickness is designed to be 1.5 mm; when the moisture content of the coal seam is within any percentage range of 10%~15%, 5%~10%, or 2%~5%, the wall thickness is taken as the midpoint of the design values ​​of the corresponding two endpoints.

[0008] In step S1, the amount of CaO particles loaded is related to the moisture content of the coal seam. When the moisture content of the coal seam is ≥10%, it is a coal seam with sufficient moisture. At this time, CaO particles are loaded according to the maximum design capacity, and the required mass of CaO particles is the baseline amount of 50g. When the moisture content of the coal seam is less than 10%, it is a coal seam with low moisture content, and the amount of CaO particles loaded needs to be reduced. When the moisture content of the coal seam is 5%, it is adjusted to 70% of the baseline amount. When the moisture content of the coal seam is less than 5%, it is adjusted to 40% of the baseline amount.

[0009] In step S1, the water-soluble polymer material is polyvinyl alcohol with a degree of hydrolysis of 88%, and the material with a fast water permeation rate is polyvinyl alcohol or gelatin with a degree of hydrolysis of 99%.

[0010] In step S1, the drying environment is an environment with a humidity of less than 15%.

[0011] In step S1, the adsorbent complex also includes paraffin or stearic acid as a slow-release agent to control the reaction rate, and copper powder or aluminum powder to enhance thermal conductivity.

[0012] In step S1, the CaO particles have a particle size of 100-300 mesh, and the activated carbon particles are coconut shell activated carbon with a high specific surface area (>1000m² / g) and a particle size of 20-100 mesh.

[0013] The beneficial effects of this invention are: 1) The method of the present invention achieves "delayed start" of the adsorption process by designing the shell material and thickness, ensuring that the capsule only starts working after reaching the target position, thus achieving precise targeted treatment and controllability of the gas adsorption position.

[0014] 2) The method of the present invention utilizes the property of calcium oxide to release heat when it comes into contact with water, which actively provides thermal excitation to the coal seam, significantly improving the desorption rate and total amount of gas, changing passive adsorption to active displacement-adsorption, and improving the efficiency of gas adsorption.

[0015] 3) The method of this invention organically combines chemical heat generation with physical adsorption. The heat-generating agent "produces" gas for the adsorbent, while the adsorbent "captures" the gas in time, forming an efficient internal cycle. The two work together to improve the amount and rate of gas adsorption.

[0016] 4) The method of the present invention is simple to operate, low in cost, easy to scale up and deliver downhole, and has good compatibility with existing drilling processes, making it highly practical. Attached Figure Description

[0017] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a schematic diagram of the structure of the hydrothermally activated gas adsorption capsule in the extraction borehole in the method of the present invention; Figure 3 This is a schematic diagram of the connection between the capsule delivery rod and the capsule fixing shaft in the method of the present invention; Figure 4 This is a schematic diagram showing the working state of the hydrothermally activated gas adsorption capsule in the extraction borehole in the method of the present invention.

[0018] In the diagram, 1-capsule outer membrane, 2-capsule inner membrane, 3-CaO particles, 4-activated carbon particles, 5-capsule fixing shaft, 6-spring, 7-spring clamp pull rope, 8-spring clamp, 9-pulley for rope reversal, 10-capsule conveying rod, 11-extraction borehole, 12-water molecule, 13-capsule outer membrane notch, 14-heat release, 15-methane molecule, 16-target coal seam. Detailed Implementation

[0019] The present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments.

[0020] like Figure 1 As shown, this invention provides a method for coalbed methane control based on hydrothermal activated adsorption capsules, comprising the following steps: S1. Preparation of hydrothermally activated adsorption capsules: A hollow capsule outer membrane 1 is formed by molding water-soluble polymer materials. The outer membrane 1 is made of polyvinyl alcohol with a degree of hydrolysis of 88% and has high mechanical strength. Its main function is to protect the internal structure from mechanical damage and premature moisture absorption during delivery. A hollow capsule inner membrane 2 is formed by molding a material with a fast water permeability. The inner membrane 2 is made of polyvinyl alcohol or gelatin with a degree of hydrolysis of 99% and has a fast water permeability. As the main activation layer, its thickness and material are precisely designed to control the timing of water permeation and capsule activation.

[0021] Based on the target activation time t a and the dissolution rate v of the shell structure material d The outer wall thickness d of the capsule inner membrane 2 is calculated using the formula: d = v d ×t a In the formula, the dissolution rate v d This refers to the reduction in thickness of the outer shell material per unit time in a simulated coal seam water environment, a value pre-determined through a standard immersion experiment; dissolution rate v d The defined formula is: v d =d1-d0 / t1-t0, where the dissolution rate v d The unit is m⋅s -1 d1 is the thickness of the inner membrane 2 after dissolution, in meters; d0 is the initial thickness of the inner membrane 2, in meters; t1 is the time after dissolution, in seconds; t0 is the initial time, in seconds.

[0022] The wall thickness d of the capsule inner membrane is related to the moisture content of the coal seam. When the moisture content of the coal seam is >15%, the wall thickness is designed to be 4 mm; when the moisture content of the coal seam is 10%, the wall thickness is designed to be 3 mm; when the moisture content of the coal seam is 5%, the wall thickness is designed to be 2 mm; when the moisture content of the coal seam is 2%, the wall thickness is designed to be 1.5 mm; when the moisture content of the coal seam is within any percentage range of 10%~15%, 5%~10%, or 2%~5%, the wall thickness is taken as the midpoint of the design values ​​of the corresponding two endpoints.

[0023] In a dry environment with humidity below 15%, an adsorbent composite is filled and sealed in a double-layer hollow shell structure. The adsorbent composite includes activated carbon particles 4 filled and sealed in the hollow structure inside the inner capsule membrane 2. Then, the inner capsule membrane 2 is placed into the outer capsule membrane 1. It also includes CaO particles 3 filled and sealed between the outer capsule membrane 1 and the inner capsule membrane 2. The mass ratio of CaO particles 3 to activated carbon particles 4 is 1:3. Finally, an adsorbent capsule is prepared.

[0024] Calculate the required mass of activated carbon particles 4 based on the amount of gas desorbed from the heat generated by CaO particles 3: 1) Estimate the maximum water volume obtainable from a single hydrothermally activated adsorption capsule: The water that the capsule can utilize mainly comes from the moisture content of the coal body within its effective influence range. Assuming that the coal body that can be effectively heated and drawn from the hydrothermal activated adsorption capsule after activation is a spherical region centered on it, the effective radius r can be roughly estimated based on the heat conduction distance or the moisture migration distance, and is approximately 10 cm.

[0025] Maximum water volume m water The calculation formula is: m water =V coal ×ρ×w, where ρ is the density of the coal seam, w is the moisture content of the coal seam, and V coal V is the volume of the coal body. coal =4 / 3πr 3 , where r is the effective radius of the water-absorbing capsule.

[0026] 2) Calculate the mass of CaO that can be reacted with the maximum amount of water: Based on the chemical reaction equation: CaO + H2O → Ca(OH)2, the mass ratio of the two reactants is calculated: 56g CaO reacts with 18g H2O, meaning that 3.11g of CaO is needed to completely react with 1g of water. Therefore, the maximum mass of CaO that the maximum water volume can support is: m CaO =m water ×56 / 18.

[0027] 3) Calculate the heat generated by CaO and estimate the amount of gas that can be desorbed: The total heat released by CaO is Qtotal Q total =m CaO / 56×64, Considering a thermal efficiency of 0.4, the amount of gas that can be desorbed, M CH4 For: M CH4 =Q total ×0.4 / H desorption In the formula, H desorption To deheat endothermic heat.

[0028] 4) Calculate the required mass of activated carbon based on the amount of gas that can be desorbed: The required activated carbon mass mAC is: mAC = M CH4 / Cac, where Cac is the adsorption capacity, and 1g of activated carbon corresponds to 0.15g of adsorbed methane.

[0029] The CaO particles 3 have a particle size of 100~300 mesh, and the activated carbon particles 4 are coconut shell activated carbon with a high specific surface area >1000m² / g and a particle size of 20~100 mesh.

[0030] S2. Deploy the adsorption capsule into the extraction borehole: like Figure 2 and Figure 3 As shown, a capsule fixing shaft 5 is provided on the outer end of the adsorption capsule. At the same time, a capsule conveying device is prepared, which includes a capsule conveying rod 10. The capsule conveying rod 10 is hollow inside and has a rectangular opening structure at one end. The upper and lower inner walls of the outer end of the rectangular opening are connected to spring clips 8 by springs 6. The two spring clips 8 are inclined from the outside of the rod to the center of the rod when there is no tension or pressure. A spring pull rope 7 is also provided inside the capsule conveying rod 10. The spring pull rope 7 is divided into two strands at the rectangular opening structure, and each strand passes around the pull rope deflector pulley 9 and is fixedly connected to the inner wall surface of the spring clip 8. The adsorption capsule is clamped and fixed between the two spring clips 8 by pushing the capsule fixing shaft 5, and then fixed on the capsule conveying rod 10. After the extraction borehole 11 is completed underground, the capsule delivery rod 10 with the adsorption capsule is placed inside the extraction borehole 11. The capsule delivery rod 10 is pushed to deliver the capsule to the target coal seam section 16. After the adsorption capsule reaches the designated position, the spring rope 7 is pulled. At this time, the spring rope 7 passes around the pull rope deflector pulley 9 and pulls the spring clamp 8, which in turn causes the two spring clamps 8 to move up and down respectively to release the capsule fixing shaft 5, thus completing the delivery of the adsorption capsule.

[0031] S3, Hydrothermal reaction activates adsorption capsules: S31. Moisture Infiltration and Activation: After the adsorption capsule is delivered to the target coal seam 16, the groundwater in the target coal seam 16 first infiltrates and dissolves the outer membrane 1 of the capsule in the form of water molecules 12, and then contacts the inner membrane 2 of the capsule and causes it to dissolve rapidly. This process occurs at the target activation time t. a Completed within the time limit; S32, Outer shell rupture: After the inner membrane 2 of the capsule dissolves, the CaO particles 3 inside it begin to come into contact with water molecules 12 and react initially to generate gas and stress, resulting in a gap 13 in the outer membrane of the capsule. S33, Hydrothermal Reaction Driven: Water molecules 12 surge in through the capsule's outer membrane opening 13, reacting violently with CaO particles 3 to release heat 14. During this reaction, the local coal temperature around the adsorption capsule rapidly rises to 60°C~120°C. This heat reduces the adsorption energy of methane on the target coal seam 16, thereby actively driving the desorption of adsorbed methane molecules 15 from the coal matrix in large quantities; Figure 4 As shown.

[0032] S4. Adsorption and capture of gas: Driven by the concentration and pressure differences, the desorbed high-concentration methane molecules 15 migrate toward the capsule and are rapidly captured and fixed by the activated carbon particles 4 exposed by the ruptured shell, thus completing the adsorption of gas.

[0033] Example 1: This example provides an adsorption capsule suitable for moderately moist coal seam conditions.

[0034] Capsule shell: Made of polyvinyl alcohol (PVA) with a degree of hydrolysis of 99%, the shell is molded into a spherical shell with an inner diameter of 8mm and an average wall thickness of 0.3mm.

[0035] Adsorbent composite: 200 mesh industrial grade calcium oxide powder (50%) and 40 mesh coconut shell activated carbon particles (50%) are mixed evenly in a dry state.

[0036] Encapsulation: Filling and sealing are completed in an environment with humidity <10%.

[0037] Field Application and Results: A 60-meter-deep extraction borehole was constructed in a coal mine. Using a specialized spray gun, 500 capsules were delivered to the depth of the borehole (40-60 meters) using compressed air. After sealing the borehole, extraction began. Observations using a distributed fiber optic temperature monitoring system within the borehole showed a significant temperature peak at depth approximately 25 minutes after delivery, confirming that the capsules had been activated and released heat. Subsequent gas flow monitoring data showed that the initial extraction concentration in this borehole was approximately 45% higher than that of the control borehole without capsules, and the concentration decay period was extended by 1.5 times.

[0038] Example 2: This example provides an adsorption capsule suitable for extremely wet coal seams or where a longer start-up time is required.

[0039] Capsule shell: 0.5% borax was added to the PVA material for mild cross-linking, and the wall thickness was increased to 0.6 mm to significantly delay water penetration.

[0040] Adsorbent complex: The ratio is adjusted to 40% calcium oxide, 58% activated carbon, and 2% stearic acid is added as a slow-release agent.

[0041] Field Application and Results: After being delivered to water-rich boreholes, the capsules only begin to release heat significantly after approximately 60-90 minutes. This "delayed start-up" characteristic ensures that the capsules have sufficient time to be delivered and distributed over a wider area, avoiding premature activation in localized areas and achieving more uniform and thorough regional treatment.

[0042] This invention achieves targeted, efficient, and proactive control of coalbed methane through a sophisticated adsorption capsule structure and delivery structure design, combined with the chemical principle of hydrothermal activation.

[0043] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for coalbed methane control based on hydrothermally activated adsorption capsules, characterized in that: Includes the following steps: S1. Preparation of hydrothermally activated adsorption capsules: A hollow outer membrane (1) of a capsule is formed by molding a water-soluble polymer material. An inner membrane (2) of a capsule is formed by molding a material with a fast water permeation rate. An adsorbent composite is filled and sealed in the double-layer hollow outer membrane under a dry environment. The adsorbent composite includes activated carbon particles (4) filled and sealed in the hollow structure inside the inner membrane (2). The inner membrane (2) is then placed into the outer membrane (1). The adsorbent composite also includes CaO particles (3) filled and sealed between the outer membrane (1) and the inner membrane (2). The mass ratio of CaO particles (3) to activated carbon particles (4) is 1:

3. Finally, an adsorbent capsule is prepared. Sa1, based on the target activation time t a and the dissolution rate v of the shell structure material d Design the wall thickness d of the capsule inner membrane (2): The formula for calculating wall thickness d is: d = v d ×t a In the formula, the dissolution rate v d It refers to the reduction in thickness of the outer shell structure material per unit time in a simulated coal seam water environment, and its value is determined in advance through a standard immersion test; Dissolution rate v d The defined formula is: v d = (d1-d0) / (t1-t0), where the dissolution rate v d The unit is m⋅s -1 d1 is the thickness of the inner membrane (2) after dissolution, in meters; d0 is the initial thickness of the inner membrane (2), in meters. t1 is the time after dissolution, in seconds; t0 is the initial time, in seconds; Sb1. Calculate the required mass of activated carbon particles (4) based on the amount of gas desorbed from the heat generated by CaO particles (3): 1) Estimate the maximum water volume obtainable from a single hydrothermally activated adsorption capsule: Assuming that after activation by the hydrothermal activated adsorption capsule, the coal body that can be effectively heated and draw water from it is a spherical region centered on it, the maximum water volume... m water The calculation formula is: m water =V coal ×ρ×w, where ρ is the density of the coal seam, w is the moisture content of the coal seam, and V coal V is the volume of the coal body. coal =4 / 3πr 3 r is the effective radius of the capsule for water absorption; 2) Calculate the mass of CaO that can be reacted with the maximum amount of water: Based on the chemical reaction equation: CaO + H2O → Ca(OH)2, the mass ratio of the two reactants is calculated: 56g CaO reacts with 18g H2O, meaning that 3.11g of CaO is needed to completely react with 1g of water. Therefore, the maximum mass of CaO that the maximum water volume can support is: m CaO =m water ×56 / 18; 3) Calculate the heat generated by CaO and estimate the amount of gas that can be desorbed: The total heat released by CaO is Q total Q total =m CaO / 56×64, Considering a thermal efficiency of 0.4, the amount of gas that can be desorbed, M CH4 For: M CH4 =Q total ×0.4 / H desorption In the formula, H desorption To desiccate endothermic; 4) Calculate the required mass of activated carbon based on the amount of gas that can be desorbed: The required activated carbon mass mAC is: mAC = M CH4 / Cac, where Cac is the adsorption capacity, and 1g of activated carbon corresponds to 0.15g of adsorbed methane. S2. Deploy the adsorption capsule into the extraction borehole: A capsule fixing shaft (5) is provided on the outer wall end of the adsorption capsule. At the same time, a capsule delivery device is prepared. The capsule delivery device includes a capsule delivery rod (10). The capsule delivery rod (10) is hollow inside and has a rectangular opening structure at one end. The upper and lower inner walls located at the outer end of the rectangular opening are connected to spring clips (8) by springs (6). The two spring clips (8) are inclined from the outside of the rod to the center of the rod when there is no tension or pressure. A spring pull rope (7) is also provided inside the capsule delivery rod (10). The spring pull rope (7) is divided into two strands at the rectangular opening structure. Each strand passes around the pull rope deflector pulley (9) and is fixedly connected to the inner wall surface of the spring clip (8). The adsorption capsule is clamped and fixed between the two spring clips (8) by pushing the capsule fixing shaft (5), and then fixed on the capsule delivery rod (10). After the extraction borehole (11) is completed in the well, the capsule delivery rod (10) with the adsorption capsule is placed inside the extraction borehole (11). The capsule delivery rod (10) is pushed to deliver the capsule to the target coal seam (16) section. After the adsorption capsule reaches the designated position, the spring rope (7) is pulled. At this time, the spring rope (7) passes around the pull rope reversing pulley (9) and pulls the spring clip (8), thereby causing the two spring clips (8) to move up and down respectively to loosen the capsule fixing shaft (5) and complete the delivery of the adsorption capsule. S3, Hydrothermal reaction activates adsorption capsules: S31. Moisture Infiltration and Activation: When the adsorption capsule is delivered to the target coal seam (16), the groundwater in the target coal seam (16) first infiltrates and dissolves the outer membrane (1) of the capsule in the form of water molecules (12), and then contacts the inner membrane (2) of the capsule and causes it to dissolve rapidly. This process occurs at the target activation time t. a Completed within the time limit; S32, Outer shell rupture: After the inner membrane (2) of the capsule dissolves, the CaO particles (3) inside it begin to come into contact with water molecules (12) and react initially to generate gas and stress, resulting in a gap (13) in the outer membrane of the capsule. S33, Hydrothermal reaction driven: Water molecules (12) rush in in large quantities through the gap (13) in the outer membrane of the capsule and react violently with CaO particles (3) to release heat (14). During this reaction, the local coal temperature around the adsorption capsule rises rapidly to 60°C~120°C. This heat reduces the adsorption energy of gas on the target coal seam (16), thereby actively driving the adsorbed methane molecules (15) to desorb in large quantities from the coal matrix. S4. Adsorption and capture of gas: Driven by the concentration and pressure difference, the desorbed high-concentration methane molecules (15) move toward the capsule and are quickly captured and fixed by the activated carbon particles (4) exposed by the shell rupture, thus completing the adsorption of gas.

2. The method for coal seam gas control based on hydrothermal activated adsorption capsules according to claim 1, characterized in that: In step S1, the wall thickness d of the inner membrane (2) of the capsule is related to the water content of the coal seam. When the water content of the coal seam is >15%, the wall thickness is designed to be 4mm; when the water content of the coal seam is 10%, the wall thickness is designed to be 3mm; when the water content of the coal seam is 5%, the wall thickness is designed to be 2mm; when the water content of the coal seam is 2%, the wall thickness is designed to be 1.5mm; when the water content of the coal seam is within any percentage range of 10%~15%, 5%~10%, or 2%~5%, the wall thickness is taken as the midpoint of the design values ​​of the two endpoints.

3. The method for coal seam gas control based on hydrothermal activated adsorption capsules according to claim 1, characterized in that: In step S1, the amount of CaO particles (3) is related to the moisture content of the coal seam. When the moisture content of the coal seam is ≥10%, it is a coal seam with sufficient moisture. At this time, CaO particles (3) are filled according to the maximum design capacity, and the required mass of CaO particles (3) is the benchmark amount of 50g. When the moisture content of the coal seam is less than 10%, it is a coal seam with low moisture content, and the amount of CaO particles (3) needs to be reduced. When the moisture content of the coal seam is 5%, it is adjusted to 70% of the benchmark amount. When the moisture content of the coal seam is less than 5%, it is adjusted to 40% of the benchmark amount.

4. The method for coal seam gas control based on hydrothermal activated adsorption capsules according to claim 1, characterized in that: In step S1, the water-soluble polymer material is polyvinyl alcohol with a degree of hydrolysis of 88%, and the material with a fast water permeation rate is polyvinyl alcohol or gelatin with a degree of hydrolysis of 99%.

5. The method for coal seam gas control based on hydrothermal activated adsorption capsules according to claim 1, characterized in that: In step S1, the drying environment is an environment with a humidity of less than 15%.

6. The method for coal seam gas control based on hydrothermal activated adsorption capsules according to claim 1, characterized in that: In step S1, the adsorbent complex also includes paraffin or stearic acid as a slow-release agent to control the reaction rate, and copper powder or aluminum powder to enhance thermal conductivity.

7. The method for coal seam gas control based on hydrothermal activated adsorption capsules according to claim 1, characterized in that: In step S1, the CaO particles (3) have a particle size of 100~300 mesh, and the activated carbon particles (4) are coconut shell activated carbon with a high specific surface area (>1000m² / g) and a particle size of 20~100 mesh.

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