A method for pressure relief and permeability improvement of a protective layer in close-range fluidized mining of a thin coal seam

Abstract

The application discloses a kind of close distance thin coal seam fluidized mining protective layer pressure relief and penetration enhancement method, it is related to coal mining technical field, including the following steps: arrangement and support structure installation;Thin coal seam coal body is ignited by ignition circuit with protection tube;Through oxygen inlet pipe input oxygen and pass through oxygen concentration sensor control air intake, promote coal body to generate carbon monoxide and hydrogen by oxidation-reduction reaction;Using air extraction pipe, air extraction control valve and generated gas detection end extract and monitor combustible gas;The cavity formed after thin coal seam reaction provides pressure relief and penetration enhancement space for lower thick coal seam.The application uses the above-mentioned close distance thin coal seam fluidized mining protective layer pressure relief and penetration enhancement method, with operation safety controllable, resource utilization rate is high, pressure relief effect is remarkable and the like advantage, it is applicable to the efficient utilization of close distance thin coal seam and the pretreatment before thick coal seam mining.

Description

Technical Field

[0001] This invention relates to the field of coal mining technology, and in particular to a method for depressurizing and enhancing permeability of protective layers in fluidized bed mining of thin coal seams at close range. Background Technology

[0002] In the coal mining industry, the mining of thin coal seams in close proximity has always faced the problem of poor economic efficiency. Traditional thin coal seam mining requires a large investment in equipment for shaft and tunnel layout and coal seam recovery, but its resource recovery rate is low and the mining cost is high, resulting in most thin coal seams in close proximity being regarded as difficult-to-mine resources and left idle.

[0003] Before mining, the lower thick coal seam needs to undergo depressurization and permeability enhancement treatment to reduce the risk of gas outbursts. Traditional methods mainly involve mining the protective layer or hydraulic fracturing. However, traditional protective layer mining also faces the cost problem of mining thin coal seams, while hydraulic fracturing is greatly limited by geological conditions and is prone to damaging the coal seam structure, resulting in unstable gas extraction efficiency.

[0004] Current thin coal seam utilization technologies have not yet formed an integrated solution of "mining + utilization + decompression": the energy of thin coal seams is not effectively recovered, and they cannot directly support the decompression and permeability enhancement of the underlying thick coal seams. Therefore, how to achieve low-cost and efficient utilization of nearby thin coal seams, while creating favorable conditions for decompression and permeability enhancement of the underlying thick coal seams, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a method for decompression and permeability enhancement of protective layers in fluidized bed mining of thin coal seams in close proximity, in order to solve the problems of high cost and poor economic efficiency in existing thin coal seam mining and low decompression and permeability enhancement efficiency in thick coal seams, and to achieve the integrated goal of fluidized bed mining and utilization of thin coal seams and decompression and permeability enhancement of thick coal seams.

[0006] To achieve the above objectives, the present invention provides a method for depressurizing and enhancing permeability of the protective layer in close-range thin coal seam fluidized mining, comprising the following steps:

[0007] S1. Excavate a roadway in the rock strata between a thin coal seam and a thick coal seam in close proximity, and install an air intake pipe and an air extraction pipe in the roadway. The air intake pipe is connected to the gas transmission motor, and the air extraction pipe is connected to the air extraction control valve and the air extraction motor in sequence. Set up a support structure in the corresponding area of ​​the thin coal seam. The support structure does not obstruct the gas flow.

[0008] S2. Arrange ignition circuits within the thin coal seam, and connect ignition switches to control the ignition timing.

[0009] S3. The ignition switch starts the ignition, igniting the coal in the thin coal seam; oxygen is supplied to the thin coal seam area through the gas supply motor and the air intake of the gas supply motor is adjusted.

[0010] S4, the gas generated by the thin coal seam reaction is extracted through the exhaust pipe by the exhaust motor, and the gas flow of the exhaust pipe is adjusted through the exhaust control valve;

[0011] S5, after the thin coal seam continues to burn and react, a cavity is formed, which provides a pressure relief and permeability enhancement space for the underlying thick coal seam, and the gas extraction work of the thick coal seam is carried out.

[0012] Preferably, the supporting structure in S1 is a net structure.

[0013] Preferably, the ignition circuit in S2 is externally sleeved with a sheath pipe, and the ignition switch is arranged outside the sheath pipe.

[0014] Preferably, in S3, an oxygen concentration sensor is arranged in the thin coal seam area, the air intake of the gas feeding motor is adjusted through the oxygen concentration sensor, when the oxygen volume concentration of the thin coal seam reaction area is lower than the preset threshold, the air intake of the gas feeding motor is increased, and when the oxygen concentration is higher than the preset threshold, the air intake of the gas feeding motor is reduced.

[0015] Preferably, in S3, the coal body undergoes the following reactions: C+O2=CO2, CO+C=2CO, H2O+C=H2+CO.

[0016] Preferably, in S3, the purity of the input oxygen is not less than 90%.

[0017] Preferably, in S4, one end of the exhaust pipe is connected with the exhaust motor, the other end is connected with the control valve, an exhaust detection pipe is arranged between the control valve and the supporting structure, one end of the exhaust detection pipe is connected with a gas detection end, and the gas detection end is arranged outside the exhaust pipe.

[0018] Preferably, in S4, the concentration of carbon monoxide and hydrogen in the extracted gas is monitored in real time by using the exhaust detection pipe and the gas detection end, when the concentration is lower than the preset utilization threshold, the opening degree of the exhaust control valve is increased, and when the concentration is higher than the preset safety threshold, the opening degree of the exhaust control valve is reduced.

[0019] Preferably, in S5, when the gas extraction work of the thick coal seam is carried out, a gas drilling hole is arranged in the thick coal seam, and the coverage area of the gas extraction drilling hole corresponds to the pressure relief range of the cavity area after the fluidized mining.

[0020] Therefore, the present application adopts the above-mentioned thin coal seam fluidized mining pressure relief and permeability enhancement method, excavates a roadway in the rock layer between the thin coal seam and the underlying thick coal seam, arranges the gas inlet pipe, the exhaust pipe, the supporting structure and the monitoring equipment, and realizes the integrated operation of the thin coal seam fluidized mining and the thick coal seam pressure relief and permeability enhancement.

[0021] The technical solutions of the present application will be further described in detail below with reference to the drawings and examples. DRAWINGS

[0022] Fig. 1 It is a structural schematic view of an embodiment of the present application for a close distance thin coal seam fluidized mining protective layer pressure relief and permeability enhancement method.

[0023] Fig. 2 It is a detailed view of the device arrangement of the present application.

[0024] Fig. 3 It is an application effect view of the present application.

[0025] Reference signs

[0026] 1, lower thick coal seam; 2, roadway; 3, air inlet pipe; 4, close distance thin coal seam; 5, rock stratum; 6, air extraction pipe; 7, gas conveying motor; 8, oxygen concentration sensor; 9, protection pipe; 10, ignition switch; 11, support structure; 12, extraction and inspection pipe; 13, gas detection end; 14, control valve; 15, air extraction motor; 16, empty cavity projection area. DETAILED DESCRIPTION

[0027] The technical solutions of the present application are further described below through the accompanying drawings and embodiments.

[0028] Unless otherwise defined, technical or scientific terms used in the present application shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Unless otherwise defined, the terms "first", "second", and the like, used in the present application do not necessarily have any order or sequence, and do not necessarily indicate any importance or priority. The terms "comprises", "comprising", "includes", "including" and the like, mean including but not limited to, and are intended to cover a wide range of elements or objects. The terms "connected", "coupled", or the like, are not limited to a physical or mechanical connection or coupling, and can include an electrical connection or coupling, whether direct or indirect. The terms "upper", "lower", "left", "right", and the like, are used only to indicate relative positions, and when the absolute positions of the described objects are changed, the relative positions may also be changed accordingly.

[0029] EMBODIMENT

[0030] Please refer to Figs. 1-3 The present application provides a close distance thin coal seam fluidized mining protective layer pressure relief and permeability enhancement method, comprising the following steps:

[0031] S1. Excavate a roadway 2 in the rock stratum 5 between the close thin coal seam 4 and the lower thick coal seam 1 for equipment installation and operation; lay an air inlet pipe 3 and an air outlet pipe 6 in the roadway, the air inlet pipe 3 extends to one side of the thin coal seam reaction area, and the other end is connected to a gas feeding motor 7 for feeding oxygen required for the reaction to the thin coal seam; the air outlet pipe 6 extends to the other side of the thin coal seam reaction area, and the other end is connected to an air outlet control valve 14 and an air outlet motor 15 in sequence for extracting carbon monoxide and hydrogen generated by the reaction.

[0032] A supporting structure 11 is arranged in the roadway 2 corresponding to the area of the thin coal seam and around the coal seam, and the supporting structure 11 is a net structure with mesh size not affecting gas flow, for maintaining the stability of the cavity pipe connection and preventing damage during the reaction process.

[0033] S2. Arrange an ignition line along the strike or dip in the thin coal seam, the ignition line uses high-temperature-resistant wires and is externally sleeved with a protective pipe 9; the protective pipe 9 is made of flame-retardant material and has a length covering the entire ignition line, for protecting the ignition line from erosion of high temperature, coal cinder and water vapor generated by the reaction of the coal seam. One end of the ignition line is connected to an ignition switch 10 for controlling the ignition timing to ensure the safety of the reaction start.

[0034] S3. Start the ignition through the ignition switch 10 to ignite the coal body in the thin coal seam; maintain the operation of the gas feeding motor 7 to continuously feed oxygen with a purity not less than 90% to the thin coal seam reaction area through the air inlet pipe 3 to ensure sufficient reaction of the coal body.

[0035] Real-time monitoring of the oxygen volume concentration in the reaction area is performed by using an oxygen concentration sensor 8 arranged in the thin coal seam reaction area, when the oxygen concentration is lower than 15%, the air intake of the gas feeding motor 7 is increased; when the oxygen concentration is higher than 20%, the air intake of the gas feeding motor 7 is reduced, so that the coal body reacts as follows under the regulation of oxygen:

[0036] 1. Preliminary oxidation reaction: C + O2 = CO2;

[0037] 2. Secondary reduction reaction: CO2 + C = 2CO;

[0038] 3. Water vapor reaction: H2O + C = H2 + CO.

[0039] By regulating the oxygen concentration, it is ensured that the reaction mainly generates carbon monoxide and hydrogen, and the combustible gas output efficiency is improved.

[0040] S4. Start the air outlet motor 15 to extract carbon monoxide and hydrogen generated by the reaction of the thin coal seam through the air outlet pipe 6; set an extraction and detection pipe 12 at the front end of the air outlet pipe 6, the extraction and detection pipe 12 is connected to a generated gas detection end 13 for real-time monitoring of the volume concentration of carbon monoxide and hydrogen in the extracted gas.

[0041] According to the monitoring result, the exhaust control valve 14 is adjusted: when the carbon monoxide and hydrogen concentration is lower than 30%, the opening of the exhaust control valve 14 is increased to increase the exhaust rate; when the concentration is higher than 70%, the opening of the exhaust control valve 14 is reduced to ensure the safety of gas extraction.

[0042] S5. In the continuous reaction process, the coal body is gradually consumed and a cavity is formed; when the thin coal seam reaction is completed, the gas inlet and exhaust are stopped, and the cavity formed at this time serves as a pressure relief space for the protective layer, so that the lower thick coal seam generates crack development due to the release of the upper load. Gas extraction pipes are arranged in the thick coal seam, the gas inlet end of the gas extraction pipe corresponds to the cavity projection area 16, and the pressure relief effect of the cavity is used to improve the gas extraction efficiency of the thick coal seam and lay a foundation for the subsequent safe mining of the thick coal seam.

[0043] Therefore, the present application adopts the above-mentioned near-distance thin coal seam fluidized mining protective layer pressure relief and permeability improvement method, by excavating a roadway in the rock stratum between the near-distance thin coal seam and the lower thick coal seam, arranging the gas inlet pipe, the exhaust pipe, the supporting structure and the monitoring equipment, the integration of the thin coal seam fluidized mining and the thick coal seam pressure relief and permeability improvement is realized. It has the advantages of safe and controllable operation, high resource utilization rate, significant pressure relief effect, etc., and is suitable for efficient utilization of near-distance thin coal seam and pretreatment before thick coal seam mining.

[0044] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application and not to limit them, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: it can still modify or equivalently replace the technical solutions of the present application, and these modifications or equivalent replacements also cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for pressure relief and permeability improvement of a protective layer in close-range thin coal seam fluidized mining, characterized in that, The method comprises the following steps: S1, excavating a roadway in the rock stratum between the close distance thin coal seam and the thick coal seam, and installing an air inlet pipe and an air outlet pipe in the roadway, the air inlet pipe being connected with a gas feeding motor, the air outlet pipe being connected with an air outlet control valve and an air outlet motor in sequence; a supporting structure is arranged in the corresponding area of the thin coal seam, and the supporting structure does not hinder the gas flow; S2, arranging an ignition circuit in the thin coal seam, the ignition circuit being connected with an ignition switch to control the ignition timing; S3, starting the ignition switch to ignite the coal body in the thin coal seam; inputting oxygen into the thin coal seam area through the air inlet pipe by the gas feeding motor, and adjusting the air inlet amount of the gas feeding motor; S4, extracting the gas generated by the reaction of the thin coal seam through the air outlet pipe by the air outlet motor, and adjusting the gas flow of the air outlet pipe through the air outlet control valve; S5, forming a cavity after the continuous combustion reaction of the thin coal seam, using the cavity to provide a pressure relief and permeability enhancement space for the thick coal seam below, and carrying out the gas extraction work of the thick coal seam.

2. The method according to claim 1, wherein the method is characterized in that: The supporting structure in S1 is a net structure.

3. The method according to claim 2, wherein the method is characterized in that: The ignition circuit in S2 is externally sleeved with a sheath pipe, and the ignition switch is arranged outside the sheath pipe.

4. The method according to claim 3, wherein the method is characterized in that: The oxygen concentration sensor is arranged in the thin coal seam area in S3, the air inlet amount of the gas feeding motor is adjusted through the oxygen concentration sensor, the air inlet amount of the gas feeding motor is increased when the oxygen volume concentration of the reaction area of the thin coal seam is lower than a preset threshold value, and the air inlet amount of the gas feeding motor is decreased when the oxygen concentration is higher than the preset threshold value.

5. The method according to claim 4, wherein, The coal body in S3 has the following reactions: C+O2=CO2, CO2+C=2CO, H2O+C=H2+CO.

6. The method according to claim 5, wherein the method is characterized in that: The purity of the input oxygen in S3 is not less than 90%.

7. The method according to claim 6, wherein the method is characterized in that: The end of the air outlet pipe is connected with the air outlet motor, the other end is connected with the control valve, the control valve and the supporting structure are provided with an air sampling pipe, the end of the air sampling pipe is connected with a gas detection end, and the gas detection end is arranged outside the air outlet pipe.

8. The method according to claim 7, wherein the method is characterized in that: The air sampling pipe and the gas detection end are used to monitor the concentrations of carbon monoxide and hydrogen in the extracted gas in real time in S4, the opening of the air outlet control valve is increased when the concentration is lower than a preset utilization threshold value, and the opening of the air outlet control valve is decreased when the concentration is higher than a preset safety threshold value.

9. The method according to claim 8, wherein the method is characterized in that: The gas extraction work of the thick coal seam is carried out in S5, a gas drilling hole is arranged in the thick coal seam, and the gas extraction drilling hole covers the pressure relief range of the cavity area after the fluidized mining.

Images