Method and equipment for efficiently extracting methane from coal

Abstract

The invention belongs to the technical field of methane extraction, and particularly relates to an efficient coal methane extraction method and device.The efficient coal methane extraction method comprises the following steps that S1, before extraction, the depth of a coal seam is detected in advance, and a horizontal well and a vertical well are erected according to the depth of the coal seam; coal-water-gas mixtures extracted through the horizontal well and the vertical well are separated and recycled; s2, during mining, an extraction pipeline system and an air return shaft are erected in a coal seam goaf, and gas is utilized according to the concentration of extracted gas; and S3, after mining, the mine is closed, a ground extraction well is erected in the goaf of the coal seam, residual methane is extracted through the ground extraction well, and methane is recycled through the concentration intelligent mixing technology. Classified extraction can be carried out according to the gas concentration before extraction, during extraction and after extraction, different utilization is carried out according to the extracted gas concentration, and then the coal methane extraction efficiency and the extraction effect can be greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of methane extraction, and in particular relates to a method and equipment for efficiently extracting methane from coal. Background Art

[0002] Coal methane extraction refers to the process of extracting methane (CH4) from underground coal mines, also known as gas extraction. The main purpose of coal methane extraction is to reduce the methane concentration underground in coal mines, prevent methane accumulation from causing explosion accidents, and ensure coal mine production safety. In addition, the extracted methane can be recycled and converted into clean energy through technical means to improve resource utilization and economic benefits.

[0003] Existing methods for extracting methane from coal include: long borehole extraction, tunnel extraction system, goaf extraction, and ground drilling extraction. Among them, long borehole extraction is to drill a long borehole in the coal seam and use negative pressure to extract methane; tunnel extraction system is to arrange extraction pipelines and equipment in the tunnel to form an extraction system; goaf extraction is to arrange extraction pipelines in the goaf and use the pressure difference in the goaf for extraction; ground drilling extraction is to drill a well on the ground and use negative pressure to extract methane from the coal seam. Although the above extraction methods can also achieve the extraction of coal methane, the extraction method is single and cannot be classified according to gas concentration. There are problems of low extraction efficiency and poor effect.

[0004] Therefore, in response to the above technical problems, it is necessary to provide a method and equipment for efficiently extracting coal methane.

[0005] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0006] The object of the present invention is to provide a method and device for efficiently extracting coal methane, which can solve the problem of single coal methane extraction method and poor effect.

[0007] In order to achieve the above object, a technical solution provided by a specific embodiment of the present invention is as follows:

[0008] A method for efficiently extracting coal methane comprises the following steps:

[0009] S1. Before mining: Detect the depth of the coal seam in advance, set up horizontal wells and vertical wells according to the depth of the coal seam, and separate and recycle the coal-water-gas mixture extracted by the horizontal wells and vertical wells;

[0010] S2. During mining: Set up extraction pipeline system and return air shaft in the coal seam goaf area and utilize the extracted gas according to its concentration;

[0011] S3. After mining: close the mine, set up surface extraction wells in the coal seam goaf, use the surface extraction wells to extract the remaining methane, and reuse the methane through concentration intelligent mixing technology.

[0012] In one or more embodiments of the present invention, in said S1, coal seam collapse and cavitation are induced and controlled in the coal seam area.

[0013] In one or more embodiments of the present invention, in S1, a water-gas separation device and a coal-water-gas separation device are installed on the ground, wherein the mixture in the coal seam that has not been subjected to hole collapse and cavitation (concentration greater than 30%) enters the water-gas separation device for separation, and the mixture in the coal seam that has been subjected to hole collapse and cavitation enters the coal-water-gas separation device, and the high-concentration methane separated by the water-gas separation device and the coal-water-gas separation device enters the storage tank and is transported to the gas station via the transportation system, and the gas station can use the methane for civil gas, automobile gas or chemical raw materials.

[0014] In one or more embodiments of the present invention, in S2, in-seam drilling extraction, through-seam drilling extraction and buried pipe extraction are carried out in the coal seam goaf.

[0015] In one or more embodiments of the present invention, low-concentration gas (concentration of 6%-30%) extracted by in-layer drilling and through-layer drilling is subjected to internal combustion engine explosion and power generation through the extraction pipeline system under the action of a water ring vacuum pump, and ultra-low-concentration gas (concentration of 1%-6%) extracted by buried pipes is subjected to lean combustion through the extraction pipeline system under the action of a water ring vacuum pump.

[0016] In one or more embodiments of the present invention, the lean combustion mode includes porous media combustion, pulsating combustion and catalytic combustion.

[0017] In one or more embodiments of the present invention, the exhaust gas in the goaf (concentration less than 1%) is oxidized and utilized or co-burned for power generation and auxiliary combustion through the return air shaft under the action of a water ring vacuum pump, wherein the oxidation utilization includes thermal countercurrent thermal storage oxidation, catalytic countercurrent oxidation and preheating catalytic oxidation.

[0018] In one or more embodiments of the present invention, S2 also includes gas purification, and the gas purification method is membrane separation, cryogenic liquefaction and pressure swing adsorption.

[0019] In one or more embodiments of the present invention, in S3, the low-concentration gas (concentration less than 30%) obtained by the concentration intelligent mixing technology is utilized through the utilization method in S2, and the obtained high-concentration gas (concentration greater than 30%) is used to generate electricity or become fuel gas.

[0020] A coal methane efficient extraction equipment includes a thermal storage oxidation device, which is used to oxidize and utilize exhaust gas. The thermal storage oxidation device includes an oxidation chamber, two thermal storage chambers interconnected through the oxidation chamber, and a switching valve. The oxidation chamber is connected to a natural gas inlet pipe and a combustion-supporting air inlet pipe, the thermal storage chamber is connected to a exhaust air inlet pipe connected to the switching valve, the top of the oxidation chamber is connected to an outlet pipe, and the outlet pipe is connected to a waste heat recovery device.

[0021] Compared with the prior art, the coal methane efficient extraction method and equipment of the present invention can classify and extract gas according to the gas concentration before, during and after mining, and make different utilizations according to the extracted gas concentration, thereby greatly improving the coal methane extraction efficiency and extraction effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 This is a schematic diagram of the structure before mining of a method for efficiently extracting coal methane in one embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the structure during and after mining of a method for efficiently extracting coal methane in one embodiment of the present invention;

[0025] Figure 3 The figure is a schematic diagram of the structure of a high-efficiency coal methane extraction device in one embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0027] like Figures 1 to 3 As shown, a method for efficiently extracting coal methane in one embodiment of the present invention comprises the following steps:

[0028] S1. Before mining: Detect the depth of the coal seam in advance, set up horizontal wells and vertical wells according to the depth of the coal seam, and separate and recycle the coal-water-gas mixture extracted by the horizontal wells and vertical wells;

[0029] S2. During mining: Set up extraction pipeline system and return air shaft in the coal seam goaf area and utilize the extracted gas according to its concentration;

[0030] S3. After mining: close the mine, set up surface extraction wells in the coal seam goaf, use the surface extraction wells to extract the remaining methane, and reuse the methane through concentration intelligent mixing technology.

[0031] In S1, the coal seam collapse is induced and controlled in the coal seam area.

[0032] Among them, the method of generating coal seam collapse holes and caves includes horizontal well cave stress release tectonic coal coalbed methane development technology.

[0033] In addition, a water-gas separation device and a coal-water-gas separation device are installed on the ground, wherein the mixture in the coal seam that has not been caved in (with a concentration greater than 30%) enters the water-gas separation device for separation, and the mixture in the coal seam that has been caved in enters the coal-water-gas separation device. The high-concentration methane separated by the water-gas separation device and the coal-water-gas separation device enters the storage tank and is transported to the gas station via the transportation system. The gas station can use the methane for domestic gas, automobile gas or chemical raw materials.

[0034] In S2, in-seam drilling and drainage, through-seam drilling and drainage, and buried pipe drainage are carried out in the coal seam goaf.

[0035] Among them, low-concentration gas (concentration of 6%-30%) extracted by in-layer drilling and through-layer drilling is used for internal combustion engine explosion and power generation through the extraction pipeline system under the action of a water ring vacuum pump, and ultra-low-concentration gas (concentration of 1%-6%) extracted by buried pipes is used for lean combustion through the extraction pipeline system under the action of a water ring vacuum pump.

[0036] Specifically, lean combustion modes include porous media combustion, pulsating combustion and catalytic combustion.

[0037] In addition, the exhaust gas in the goaf (concentration less than 1%) is oxidized or co-burned for power generation and auxiliary combustion through the return air shaft under the action of the water ring vacuum pump. The oxidation utilization includes thermal countercurrent thermal storage oxidation, catalytic countercurrent oxidation and preheating catalytic oxidation.

[0038] In addition, S2 also includes a gas purification process to convert low-concentration gas into high-concentration gas. Through gas purification, the difficulty of utilization is reduced and the utilization efficiency is improved. The gas purification methods are membrane separation, cryogenic liquefaction and pressure swing adsorption.

[0039] In S3, the low-concentration gas (concentration less than 30%) obtained through the concentration intelligent mixing technology is utilized through the utilization method in S2, and the obtained high-concentration gas (concentration greater than 30%) is used to generate electricity or become fuel gas.

[0040] A coal methane efficient extraction equipment includes a thermal storage oxidation device, which is used to oxidize and utilize exhaust gas. The thermal storage oxidation device includes an oxidation chamber, two thermal storage chambers interconnected through the oxidation chamber, and a switching valve. The oxidation chamber is connected to a natural gas inlet pipe and a combustion-supporting air inlet pipe, the thermal storage chamber is connected to a exhaust air inlet pipe connected to the switching valve, the top of the oxidation chamber is connected to an outlet pipe, and the outlet pipe is connected to a waste heat recovery device.

[0041] After the exhaust air and extracted gas are safely collected and mixed to reach a methane concentration of 1.2%, they are transported to the thermal storage oxidation device. The mixed gas is instantly oxidized in a high-temperature environment of 930℃±25℃, releasing oxidation heat. In addition to meeting the heat demand of the device itself, this oxidation heat will also generate a large amount of waste heat. This part of heat is drawn out from the top of the thermal storage oxidation device in the form of high-temperature flue gas and enters the waste heat recovery equipment.

[0042] Among them, the waste heat recovery equipment includes a waste heat boiler and a steam turbine generator set, that is, the high-temperature flue gas from the thermal storage oxidation device is passed through the waste heat boiler to generate superheated steam, and the hot steam is introduced into the steam turbine generator set to generate electricity and also provide heat.

[0043] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0044] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for efficiently extracting coal methane, characterized in that: The following steps are involved: S1. Before mining: Detect the depth of the coal seam in advance, set up horizontal wells and vertical wells according to the depth of the coal seam, and separate and recycle the coal-water-gas mixture extracted by the horizontal wells and vertical wells; S2. During mining: Set up extraction pipeline system and return air shaft in the coal seam goaf area and utilize the extracted gas according to its concentration; S3. After mining: close the mine, set up surface extraction wells in the coal seam goaf, use the surface extraction wells to extract the remaining methane, and reuse the methane through concentration intelligent mixing technology.

2. A method for efficient extraction of coal methane according to claim 1, characterized in that: In said S1, coal seam collapse and hole formation are induced in the coal seam area.

3. A method for efficient extraction of coal methane according to claim 2, characterized in that: In the S1, a water-gas separation device and a coal-water-gas separation device are installed on the ground, wherein the mixture in the coal seam that has not been subjected to hole collapse and cavitation enters the water-gas separation device for separation, and the mixture in the coal seam that has been subjected to hole collapse and cavitation enters the coal-water-gas separation device, and the high-concentration methane separated by the water-gas separation device and the coal-water-gas separation device enters the storage tank and is transported to the gas station through the transportation system.

4. A method for efficient extraction of coal methane according to claim 1, characterized in that: In the S2, in-seam drilling extraction, through-seam drilling extraction and buried pipe extraction are carried out in the coal seam goaf.

5. A method for efficient extraction of coal methane according to claim 4, characterized in that: The low-concentration gas extracted through in-layer drilling and through-layer drilling is used for internal combustion engine explosion and power generation through the extraction pipeline system under the action of a water ring vacuum pump. The ultra-low-concentration gas extracted through buried pipes is used for lean combustion through the extraction pipeline system under the action of a water ring vacuum pump.

6. A method for efficient extraction of coal methane according to claim 5, characterized in that: The lean combustion modes include porous medium combustion, pulsating combustion and catalytic combustion.

7. A method for efficient extraction of coal methane according to claim 1, characterized in that: The exhaust gas in the goaf is oxidized and utilized through the return air shaft or co-burned for power generation and auxiliary combustion under the action of the water ring vacuum pump.

8. The method for efficient extraction of coal methane according to claim 1, characterized in that: Said S2 also includes gas purification, and the gas purification methods are membrane separation, cryogenic liquefaction and pressure swing adsorption.

9. A method for efficient extraction of coal methane according to claim 6, 7 or 8, characterized in that: In S3, the low-concentration gas obtained by the concentration intelligent mixing technology is utilized through the utilization method in S2, and the obtained high-concentration gas is used to generate electricity or become fuel gas.

10. A coal methane efficient extraction device, used to implement the coal methane efficient extraction method according to any one of claims 1 to 9, characterized in that: The extraction equipment includes a heat storage oxidation device, which is used to oxidize and utilize the exhaust gas. The heat storage oxidation device includes an oxidation chamber, two heat storage chambers interconnected by the oxidation chamber, and a switching valve. The oxidation chamber is connected to a natural gas inlet pipe and a combustion-supporting air inlet pipe, the heat storage chamber is connected to a exhaust air inlet pipe connected to the switching valve, the top of the oxidation chamber is connected to an outlet pipe, and the outlet pipe is connected to a waste heat recovery device.

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