A device and operation method for promoting gas desorption by heating in coal mines

Abstract

The present invention proposes a device for promoting gas desorption by heating underground in coal mines, including a heating drill pipe, a water inlet pipe, a heating pipe, a water return pipe and a metal hose with a joint; metal hoses are installed at both ends of the water inlet pipe, the heating pipe and the water return pipe; wherein the water inlet pipe and the water return pipe are respectively installed on the outside of both sides of the heating drill pipe; the heating pipe sleeve is installed inside the heating drill pipe; the two ends of the heating pipe are respectively connected to the water inlet pipe and the water return pipe through the metal hose. The present invention is easy and quick to install, and the installation length can be adjusted according to actual needs; the use of parallel pipelines can ensure that the temperature around the drill pipes of each unit length is consistent, so that the desorption of the coal body in the entire borehole remains consistent; using water as the heat transfer medium is safer and more efficient.

Description

Technical Field

[0001] The invention belongs to the technical field of coal seam gas extraction, and specifically relates to a device and an operating method for promoting gas desorption by heating in an underground coal mine. Background Art

[0002] For safe production in coal mines, gas disaster prevention and control is of paramount importance. As the mining depth of the mine increases, the ground stress continues to increase, the gas content increases accordingly, and the gas hazard coefficient is also rising. The most important measure for the prevention and control of gas disasters is to prevent gas accumulation and eliminate gas outbursts, and gas extraction is the most effective way to control the gas concentration of coal seams and eliminate gas outbursts in mining working faces.

[0003] Gas extraction is a complex engineering technology. For low permeability, high gas content and outburst coal seams, increasing the gas extraction flow rate depends on the content of free gas in the coal seams, and fundamentally, it depends on the adsorption characteristics of coal to gas. The adsorption characteristics of coal are an important basis for studying the laws of coal and gas outbursts and the development and utilization of coalbed methane. Through the summary, induction and analysis of the experimental research results on the influence of coal body gas adsorption characteristics conducted by experts and scholars in the past decade, temperature is also an important factor affecting the adsorption characteristics of coal. Under the same gas pressure, the gas adsorption amount of coal bodies with the same coal quality decreases with the increase of temperature. In other words, as the temperature increases, the gas diffusion rate increases, which promotes the desorption of coal seam gas and increases the free gas content in the coal seam, which is more conducive to the extraction of coal seam gas.

[0004] The related research on increasing the desorption of coal seam gas by increasing the temperature is still in its infancy and urgently needs technical support from corresponding equipment and processes. Summary of the invention

[0005] The present invention is based on at least one of the above-mentioned technical problems and provides a device for promoting gas desorption by heating in coal mines. The device is easy and quick to install and the installation length can be adjusted according to actual needs. The parallel pipelines are used to ensure that the temperature around the drill rods of each unit length remains consistent, so that the desorption of the coal body in the entire borehole remains consistent. Water is used as the heat transfer medium, which is safer and more efficient.

[0006] In view of this, the present invention proposes a device for promoting gas desorption by heating in underground coal mines, comprising a heating drill rod, a water inlet pipe, a heating pipe, a return pipe and a metal hose with a joint; metal hoses are installed at both ends of the water inlet pipe, the heating pipe and the return pipe; wherein the water inlet pipe and the return pipe are respectively installed on the outside of both sides of the heating drill rod; the heating pipe sleeve is installed inside the heating drill rod; and the two ends of the heating pipe are respectively connected to the water inlet pipe and the return pipe through metal hoses.

[0007] Preferably, the metal hose is a bendable metal hose.

[0008] After the coal seam extraction drilling construction is completed, the present invention connects several heating-promoting gas desorption devices, and sends the connected several heating-promoting gas desorption devices into the borehole. To prevent the drill from getting stuck, a conventional drill bit is installed at the front end of the heating drill rod, and the end is connected to the underground extraction circuit. After reaching the specified depth, the end of the device water inlet pipe is connected to the water outlet of the external heating circuit, and the end of the return pipe is connected to the water inlet of the heating circuit. The circuit is started, and as the hot water circulates along the circuit, the temperature of the coal body near the borehole can be increased, thereby promoting desorption and increasing the gas extraction volume.

[0009] Furthermore, the connector includes a tee connector, a straight connector and a right-angle connector.

[0010] Among them, the metal hose connected at both ends of the heating pipe is connected to a right-angle joint, and the metal hose connected to the front end of the water inlet pipe is connected to a straight-through joint; the metal hose connected to the end of the water inlet pipe is connected to a three-way joint, wherein the three-way joint on the metal hose connected to the end of the water inlet pipe is connected to the right-angle joint on the metal hose connected to one end of the heating pipe; wherein the metal hose connected to the front end of the return pipe is connected to a three-way joint; the metal hose connected to the end of the return pipe is connected to a straight-through joint; wherein the three-way joint on the metal hose connected to the front end of the return pipe is connected to the right-angle joint on the metal hose connected to the other end of the heating pipe, forming a water cycle. During use, the present invention connects multiple devices for heating up to promote gas desorption, wherein each heating unit is in a parallel structure to ensure that the overall temperature is uniform.

[0011] Furthermore, the heated drill rod is a cylindrical cavity structure, the front end is a tapered external thread, and the end is a tapered internal thread; the front end and the rear end of the heated drill rod are adapted to each other.

[0012] In the present invention, the front end of the rear heating drill rod in the two heating-promoting gas desorption devices is connected and adapted to the rear end of the front heating drill rod to form a series connection. At the same time, after multiple heating drill rods are connected, the straight-through joint on the metal hose connected to the front end of the rear water inlet pipe is connected to the three-way joint on the metal hose connected to the end of the previous water inlet pipe to realize the series connection of the water inlet pipes. To ensure the closedness of the loop, the front end interface of the straight-through joint on the metal hose connected to the front end of the water inlet pipe of the frontmost heating drill rod is closed. Similarly, to realize the series connection of the return water pipes, the front end interface of the three-way joint on the metal hose connected to the front end of the return water pipe of the frontmost heating drill rod is closed.

[0013] Furthermore, the non-connecting threaded parts at both ends of the heated drill pipe are processed with mounting holes; and the mounting holes are adapted to the size of the joints.

[0014] In the present invention, the three-way joint connected to the metal hose connected to the end of the water inlet pipe is installed in the mounting hole on the heating drill rod; the three-way joint on the metal hose connected to the front end of the return pipe is installed in the mounting hole on the heating drill rod.

[0015] Furthermore, the water inlet pipe is a metal pipe; the metal pipe is made of copper or aluminum.

[0016] Furthermore, the return pipe and the inlet pipe are centrally symmetrically distributed and arranged outside the heated drill pipe. The material of the return pipe is the same as that of the inlet pipe.

[0017] Furthermore, the heating pipe is a spiral structure; the material of the heating pipe is the same as that of the water inlet pipe.

[0018] According to the second aspect of the present invention, a method for operating a device for promoting gas desorption by heating underground in a coal mine is proposed, comprising the following steps:

[0019] (1) After the gas extraction drilling is completed, the drilling tool is withdrawn. The diameter of the drilling hole is 94-100 mm. The extraction hole is temporarily sealed with a water-expansion or air-expansion sealer in coal mines to achieve simple extraction.

[0020] (2) Connect the temperature-raising gas desorption devices, and use a drilling rig to send several connected temperature-raising gas desorption devices into the extraction borehole until they reach the bottom of the hole;

[0021] (3) Connect the heated drill pipe to the underground extraction circuit, and connect the water inlet pipe and the water return pipe to the underground heating circuit respectively, that is, while the pipeline heats the coal body around the borehole, the gas in the borehole is extracted; the heating circuit includes a water heater, a water tank and a circulating water pump equipment;

[0022] (4) Start the heating circuit and monitor the temperature and pressure in real time. The temperature is generally not higher than 100°C to avoid gasification of the circulating water medium. The pressure is generally not higher than 0.5MPa. When the gas extraction volume drops to a certain limit, withdraw the device, recycle it, and proceed to the next hole operation.

[0023] The limit value is defined as follows: the gas extraction within the control range of the borehole is calculated to meet the standard or the increase in gas extraction after heating is less than 20%.

[0024] The heated drill pipe has a cylindrical cavity structure and can be used as an extraction channel. The cylindrical cavity structure of the heated drill pipe is connected to the underground extraction circuit using the mine extraction pipe. The extraction circuit laid underground is connected to the mine extraction main pipe to achieve negative pressure extraction.

[0025] Through the above technical scheme, the present invention provides a device for heating up and promoting gas desorption in coal mines. The device is easy and quick to install, and the installation length can be adjusted according to actual needs. The parallel pipeline is adopted to ensure that the temperature around the drill rods of each unit length remains consistent, so that the desorption of the coal body in the entire borehole remains consistent. Water is used as the heat transfer medium, which is safer and more efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The following is a diagram showing the use and installation of the temperature-raising gas desorption-promoting device of the present invention.

[0027] Figure 2 The schematic diagram of the structure of the temperature-raising gas desorption promoting device of the present invention is shown.

[0028] Figure 3 A cross-sectional view of the temperature-raising gas desorption promoting device of the present invention is shown.

[0029] Figure 4 The schematic diagram of the structure of the three-way connector of the present invention is shown.

[0030] Figure 5 The schematic diagram of the structure of the straight-through connector of the present invention is shown.

[0031] Figure 6 The schematic diagram of the structure of the right angle joint of the present invention is shown.

[0032] Among them, in the figure, 1 is a heated drill pipe, 2 is a water inlet pipe, 3 is a heating pipe, 4 is a return pipe, A is a three-way joint, B is a straight joint, C is a right-angle joint, and D is a metal hose. DETAILED DESCRIPTION

[0033] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0034] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0035] The present invention provides a device for promoting gas desorption by heating in coal mines. The device is easy and quick to install, and the installation length can be adjusted according to actual needs. The parallel pipeline is adopted to ensure that the temperature around the drill rods of each unit length is kept consistent, so that the desorption of the coal body in the entire borehole is kept consistent. Water is used as the heat transfer medium, which is safer and more efficient. The structure is as follows: Figure 1-6 .

[0036] like Figure 1-6The present invention proposes a device for promoting gas desorption by heating in coal mines, comprising a heating drill pipe 1, a water inlet pipe 2, a heating pipe 3, a return pipe 4 and a metal hose D with a joint; metal hoses D are installed at both ends of the water inlet pipe 2, the heating pipe 3 and the return pipe 4; the water inlet pipe 2 and the return pipe 4 are respectively installed on the outside of both sides of the heating drill pipe 1; the heating pipe 3 is sleeved and installed inside the heating drill pipe 1; the two ends of the heating pipe 3 are respectively connected to the water inlet pipe 2 and the return pipe 4 through the metal hose D.

[0037] In order to further optimize the technical solution, it is proposed that the joints include a three-way joint A, a straight joint B and a right-angle joint C.

[0038] In order to further optimize the technical solution, it is proposed that the heated drill rod 1 is a cylindrical cavity structure, the front end is a tapered external thread, and the end is a tapered internal thread; the front end and the rear end of the heated drill rod 1 are adapted to each other.

[0039] In order to further optimize the technical solution, it is proposed that the non-connecting threaded parts at both ends of the heating drill rod 1 are processed with mounting holes; the mounting holes are adapted to the size of the joints.

[0040] In order to further optimize the technical solution, it is proposed that the water inlet pipe 2 is a metal pipe; the material of the metal pipe is copper or aluminum.

[0041] In order to further optimize the technical solution, it is proposed that the return pipe 4 and the inlet pipe 2 are centrally symmetrically distributed and arranged outside the heated drill pipe 1 , and the material of the return pipe 4 is the same as that of the inlet pipe 2 .

[0042] In order to further optimize the technical solution, it is proposed that the heating tube 3 is a spiral structure; the material of the heating tube 3 is the same as that of the water inlet tube 2.

[0043] The principle and use method of the present invention are as follows: first, several temperature-increasing gas desorption devices are connected, wherein the metal hose D at the end of the water inlet pipe 2 is connected to the A3 interface of the three-way joint A, and the metal hose D at the front end of the water inlet pipe 2 is connected to the B1 interface of the straight joint B. After multiple temperature-increasing drill pipes 1 are connected, the B2 interface of the straight joint B of the rear water inlet pipe 2 is connected to the A2 interface of the three-way joint A of the front water inlet pipe 2 to realize the series connection of the water inlet pipes 2. To ensure the closedness of the loop, the B2 interface of the straight joint B on the front end metal hose D of the water inlet pipe 2 on the front end temperature-increasing gas desorption device is closed.

[0044] The A1 interface of the three-way joint A on the metal hose D at the end of the water inlet pipe 2 of the heating-promoting gas desorption device is installed in the mounting hole on the heating drill rod 1; the A1 interface of the three-way joint A on the metal hose D at the front end of the return pipe 4 of the heating-promoting gas desorption device is installed in the mounting hole on the heating drill rod 1.

[0045] Metal hoses D are connected to both ends of the heating pipe 3, and the ends of the metal hoses D are connected to the C2 interfaces of the right-angle joint C. The C1 interfaces of the right-angle joint C are respectively connected to the A1 interfaces of the three-way joints A of the water inlet pipe 2 and the water return pipe 4 to realize parallel connection of the heating parts.

[0046] After the gas extraction drilling is completed by the underground drilling rig, the drilling tool is withdrawn, wherein the borehole diameter is 94mm, and the extraction hole is temporarily sealed by a water-expansion or air-expansion hole sealer used in coal mines to achieve simple extraction; a temperature-increasing gas desorption device is connected, and several temperature-increasing gas desorption devices connected are sent into the extraction borehole by the drilling rig until the bottom of the borehole;

[0047] The heating drill pipe 1 is a cylindrical cavity structure. The heating drill pipe 1 is connected to the underground extraction circuit and can be used as an extraction channel. The extraction circuit laid underground is connected to the mine extraction main pipe to achieve negative pressure extraction. The water inlet pipe 2 and the water return pipe 4 are respectively connected to the underground heating circuit, that is, while the pipeline heats the coal body around the borehole, the gas in the borehole is extracted; the heating circuit includes a water heater, a water tank and a circulating water pump equipment; start the heating circuit, monitor the temperature, pressure, etc. in real time, the temperature is generally not higher than 100°C to avoid gasification of the circulating water medium, and the pressure is generally not higher than 0.5MPa; after the gas extraction volume drops to a certain limit value, withdraw the device, recycle it, and proceed to the next hole operation. The limit value is defined as: calculate the gas extraction within the control range of the borehole to meet the standard or the increase in gas extraction after heating is less than 20%.

[0048] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A device for promoting gas desorption by heating in coal mines, characterized in that: It includes a heating drill pipe, a water inlet pipe, a heating pipe, a return pipe and a metal hose with a joint; metal hoses are installed at both ends of the water inlet pipe, the heating pipe and the return pipe; the water inlet pipe and the return pipe are respectively installed on the outside of both sides of the heating drill pipe and are symmetrically distributed around the center, and the return pipe is made of the same material as the water inlet pipe; the heating pipe is a spiral structure and is installed inside the heating drill pipe; both ends of the heating pipe are connected to the water inlet pipe and the return pipe respectively through the metal hose, and the heating pipe is made of the same material as the water inlet pipe; a conventional drill bit is installed at the front end of the heating drill pipe, and its end is connected to an underground extraction circuit.

2. The device for promoting gas desorption by heating in underground coal mines according to claim 1, characterized in that: The joints include tee joints, straight joints and right-angle joints.

3. A device for promoting gas desorption by heating in coal mines according to claim 1 or 2, characterized in that: The heating drill rod is a cylindrical cavity structure, the front end is a tapered external thread, and the end is a tapered internal thread; the front end and the rear end of the heating drill rod are adapted to each other.

4. The device for promoting gas desorption by heating in underground coal mines according to claim 3 is characterized in that: The non-connecting threaded parts at both ends of the heating drill rod are processed with mounting holes; the mounting holes are adapted to the size of the joints.

5. The device for promoting gas desorption by heating in underground coal mines according to claim 1, characterized in that: The water inlet pipe is a metal pipe; the material of the metal pipe is copper or aluminum.

6. A method for operating the device according to any one of claims 1 to 5, characterized in that: The steps include: (1) After the gas extraction drilling is completed by the underground drilling rig, the drilling tool is withdrawn, where the drilling hole diameter is 94-100mm and the extraction hole is temporarily sealed; (2) Connecting the temperature-raising gas desorption-promoting device, and using a drilling rig to send the connected temperature-raising gas desorption-promoting devices into the extraction borehole until they reach the bottom of the borehole; (3) connecting the heated drill pipe to the underground extraction circuit, and connecting the water inlet pipe and the water return pipe to the underground heating circuit respectively, that is, while the pipeline heats the coal body around the borehole, the gas in the borehole is extracted; (4) Start the heating circuit and monitor the temperature and pressure in real time. The temperature shall not exceed 100°C and the pressure shall not exceed 0.5MPa. When the gas extraction volume drops to a certain limit, withdraw the device, recycle it, and proceed to the next hole operation.

7. The method for operating the device according to claim 6, characterized in that: The limit value is defined as: the gas extraction within the control range of the borehole meets the standard or the increase in gas extraction volume after heating is less than 20%.

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