Carbon dioxide pump injection system for use in coal mines

Abstract

The present application relates to the technical field of carbon dioxide geological storage, and provides a carbon dioxide pumping system for underground coal mines, which comprises a liquid storage device, a heating device, a pumping device, a pressure regulating device and a remote control device, the liquid storage device comprises a first container for containing liquid carbon dioxide fracturing agent; the heating device comprises heat exchange pipes arranged in the first container, a heat medium is adapted to flow in the heat exchange pipes to exchange heat between the heat medium and the liquid carbon dioxide fracturing agent in the first container; the input end of the pumping device is communicated with the first container, and the output end is used for being communicated to a fracturing borehole; the pumping device is used for pumping the liquid carbon dioxide fracturing agent in the first container to the fracturing borehole; the pressure regulating device is connected with the pumping device to control the pumping pressure of the pumping device; and the remote control device is connected with the heating device, the pumping device and the pressure regulating device through signal cables to control the heating device, the pumping device and the pressure regulating device outside the coal mine.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide geological storage technology, and in particular to a carbon dioxide pump injection system for underground coal mines. Background Technology

[0002] Carbon capture, utilization, and storage (CCUS) is a large-scale greenhouse gas emission reduction technology. As a traditional high-carbon petrochemical energy industry, the coal industry urgently needs to develop carbon dioxide emission reduction or storage solutions with industrial applicability.

[0003] Coal seams that are unminable due to technical or economic reasons are common in coal-bearing strata. Fracturing technology can create a network of fractures in underground coal and rock formations, which can improve formation stress and increase reservoir permeability. By using fracturing technology to sequester carbon dioxide within unminable coal seams, a relatively permanent carbon dioxide sequestration can be achieved, providing an effective emission reduction pathway for the coal and coal-fired power industries.

[0004] Currently, most underground fracturing technologies in my country's coal mines use water-based fracturing fluids, which contain various chemical additives, posing potential environmental pollution risks. Therefore, there is an urgent need for rapid and efficient pumping equipment adapted to underground carbon dioxide fracturing operations in coal mines. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a carbon dioxide pumping system for underground coal mines, which overcomes the deficiency in existing technologies of lacking rapid and efficient pumping equipment suitable for underground carbon dioxide fracturing operations in coal mines, and realizes waterless carbon dioxide fracturing pumping in underground coal mines.

[0006] This invention provides a carbon dioxide injection system for underground coal mines, comprising:

[0007] A liquid storage device, including a first container for containing liquid carbon dioxide fracturing agent;

[0008] The heating device includes a heat exchange tube partially disposed within the first container, the heat exchange tube being adapted for the flow of a heat medium, so that the heat medium flows through the heat exchange tube and exchanges heat with the liquid carbon dioxide fracturing agent in the first container;

[0009] A pumping device, with its input end connected to the first container and its output end connected to a fracturing borehole, is used to pump the liquid carbon dioxide fracturing agent in the first container to the fracturing borehole.

[0010] A pressure regulating device, connected to the pumping device, is used to control the pumping pressure of the pumping device within the coal mine; and

[0011] A remote control device is connected to the heating device, the pumping device, and the pressure regulating device via signal cables, and is used to control the heating device, the pumping device, and the pressure regulating device from outside the coal mine.

[0012] According to the present invention, a carbon dioxide pump injection system for underground coal mines includes a heating device further comprising a sealed heating component disposed outside the first container. The inlet and outlet of the heat exchange tube are disposed outside the first container and connected to the sealed heating component. The heat medium can circulate within the sealed heating component and the heat exchange tube. The sealed heating component is used to heat the heat medium.

[0013] According to the present invention, a carbon dioxide pump injection system for underground coal mines is provided, wherein the heating device further includes a heat exchange valve disposed at the inlet and / or outlet of the heat exchange tube, the heat exchange valve being used to control the flow rate of the heat medium in the heat exchange tube located in the first container.

[0014] According to the present invention, a carbon dioxide pumping system for underground coal mines is provided, wherein the heat exchange tube extends into the first container from the bottom and extends out of the first container from the top.

[0015] According to the present invention, a carbon dioxide injection system for underground coal mines is provided, wherein the pumping device includes a fluid fracturing pump and a coal safety type variable frequency motor, wherein the pump inlet of the fluid fracturing pump is connected to the first container and the pump outlet is connected to the fracturing borehole through a pipeline; and the coal safety type variable frequency motor is connected to the fluid fracturing pump.

[0016] According to the present invention, a carbon dioxide pump injection system for underground coal mines includes a pressure control device comprising a coal mine-permitted frequency converter, which is connected to the coal safety-type frequency converter motor via a control cable.

[0017] According to the present invention, a carbon dioxide pump injection system for underground coal mines is provided, wherein the liquid storage device includes a plurality of first containers.

[0018] According to the present invention, a carbon dioxide injection system for underground coal mines is provided, wherein the pumping device further includes a high-pressure valve, and the pump inlet of the fluid fracturing pump is connected to a plurality of first containers through the high-pressure valve.

[0019] According to the present invention, a carbon dioxide pumping system for underground coal mines is provided, the carbon dioxide pumping system for underground coal mines further includes a storage and transportation device, the storage and transportation device including a second container for containing liquid carbon dioxide fracturing agent, the second container being able to communicate with or separate from the first container; and the storage and transportation device being movable.

[0020] According to the present invention, a carbon dioxide injection system for underground coal mines is provided, wherein the storage and transportation equipment further includes a mobile vehicle and a booster pump, the second container and the booster pump are mounted on the mobile vehicle, and the second container is connected to the first container through the booster pump; the mobile vehicle includes a rubber-wheeled walking mechanism and a hook, the hook being adapted to connect to an underground coal mine transport vehicle.

[0021] The carbon dioxide injection system for underground coal mines provided by this invention is suitable for non-toxic, harmless, and pollution-free liquid carbon dioxide fracturing agents. It boasts advantages such as safety, reliability, absence of aqueous phase, absence of residue, and rapid return flow. By incorporating heating and pressure regulating devices, the temperature and pressure of the liquid carbon dioxide fracturing agent are controlled. The liquid carbon dioxide fracturing agent is pressurized and injected into the formation fracturing borehole via a pumping device, achieving waterless carbon dioxide fracturing injection in underground coal mines. This system can be used for high-volume, high-pressure fracturing in underground coal mines or for carbon dioxide geological storage operations in unminable coal seams. Based on carbon dioxide capture, utilization, and storage technology, it can achieve near-zero emissions from fossil fuels, benefiting coal and coal... The power industry has explored effective emission reduction pathways; remote control equipment enables remote control of the pumping system's operating parameters, allowing for remote operation and control of fracturing operations. This avoids personnel entering the fracturing area during the fracturing process, ensuring construction safety and continuous pumping operations in coal mines with high efficiency. Moreover, the pumping system has a simple structure and compact layout, making it suitable for the confined working spaces in coal mines. It provides the coal industry with a new type of efficient, green, and waterless formation fracturing equipment with controllable temperature and pressure in coal mines, possessing significant engineering application value. This effectively addresses the shortcomings of existing technologies that lack rapid and efficient pumping equipment suitable for carbon dioxide fracturing operations in coal mines. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a front view of the carbon dioxide pumping system for underground coal mines provided by the present invention;

[0024] Figure 2 This is a top view of the carbon dioxide pumping system for underground coal mines provided by the present invention.

[0025] Figure label:

[0026] 1: Liquid storage device; 2: Heating device; 3: Pumping device;

[0027] 4. Pressure regulating device; 5. Remote control equipment; 6. Signal cable;

[0028] 7: Control cables; 8: Storage and transportation equipment; 11: First container;

[0029] 21: Heat exchange tube; 22: Sealed heating assembly; 23: Heat exchange valve;

[0030] 31: Fluid fracturing pump; 32: Coal safety type variable frequency motor; 33: High-pressure valve;

[0031] 34: High-pressure pipeline; 81: Second container; 82: Mobile vehicle;

[0032] 83: Booster pump; 821: Rubber wheel walking mechanism. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0034] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "first" and "second" are used to clearly indicate product components and do not represent any substantial difference. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0035] It should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly; for example, it can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this invention based on the specific circumstances.

[0036] The following is combined with Figure 1 and Figure 2 The present invention describes a carbon dioxide pumping system for underground coal mines.

[0037] like Figure 1As shown, the carbon dioxide injection system for underground coal mines provided by this invention includes a liquid storage device 1, a heating device 2, a pumping device 3, a pressure regulating device 4, and a remote control device 5. The liquid storage device 1 includes a first container 11 for holding liquid carbon dioxide fracturing agent. The heating device 2 includes a heat exchange tube 21 partially disposed within the first container 11, with a heat exchange medium suitable for flow within the heat exchange tube 21, so that the heat exchange medium exchanges heat with the liquid carbon dioxide fracturing agent in the first container 11 as it flows through the heat exchange tube 21, thereby heating the liquid carbon dioxide fracturing agent in the first container 11. The input end of the pumping device 3 is connected to the first container 11, and the output end is connected to a fracturing borehole. The pumping device 3 is used to pump the liquid carbon dioxide fracturing agent in the first container 11 to the fracturing borehole. The pressure regulating device 4 is connected to the pumping device 3 and is used to control the pumping pressure of the pumping device 3 within the coal mine. The remote control device 5 is connected to the heating device 2, the pumping device 3 and the pressure regulating device 4 via the signal cable 6. The remote control device 5 is used to control the working status of the heating device 2, the pumping device 3 and the pressure regulating device 4 outside the coal mine.

[0038] The underground carbon dioxide pumping system in the above embodiments is suitable for non-toxic, harmless, and pollution-free liquid carbon dioxide fracturing agents. It has advantages such as safety, reliability, absence of aqueous phase, absence of residue, and rapid return flow. By setting up a heating device 2 and a pressure regulating device 4, the temperature and pressure of the liquid carbon dioxide fracturing agent are controlled. The liquid carbon dioxide fracturing agent is pressurized and injected into the formation fracturing borehole through a pumping device 3, achieving waterless carbon dioxide fracturing pumping in coal mines. It can be used for high-volume, high-pressure fracturing in coal mines or for carbon dioxide geological storage operations in unminable coal seams. Based on carbon dioxide capture, utilization, and storage technology, it can achieve near-zero emissions of fossil energy, providing a safe environment for coal mining. It explores effective emission reduction paths with the coal and power industry; the remote control equipment 5 enables remote control of the pumping system's operating parameters, realizing remote operation and control of fracturing operations, avoiding personnel entering the fracturing operation area during fracturing, ensuring construction safety, ensuring continuous pumping operations in coal mines, and high construction efficiency; moreover, the pumping system has a simple structure and compact layout, suitable for the narrow working space in coal mines, providing the coal industry with a new type of efficient, green, and waterless formation fracturing equipment with controllable temperature and pressure in coal mines, which has significant engineering application value, thus effectively solving the deficiency of existing technologies in lacking fast and efficient pumping equipment adapted to carbon dioxide fracturing operations in coal mines.

[0039] In one specific embodiment, the first container 11 is a high-temperature reaction vessel, made of high-strength, thick-walled, pressure-resistant steel, with a pressure resistance of 100 MPa. The first container 11 is cylindrical, with a capacity of 3-5 cubic meters, determined according to the actual construction scale.

[0040] Optionally, such as Figure 2As shown, the liquid storage device 1 includes multiple first containers 11, such as two. By equipping multiple first containers 11, a multi-path configuration can be achieved, ensuring continuous operation of fracturing pump injection, meeting the needs of large-volume continuous fracturing, and realizing continuous fracturing operations in coal mines.

[0041] Specifically, the heating device 2 is integrated with multiple first containers 11 in a compact arrangement, which is suitable for the narrow working space in underground coal mines.

[0042] In one specific embodiment, the heating device 2 is disposed between the two first containers 11.

[0043] Specifically, such as Figure 2 As shown, the heating device 2 also includes a sealed heating component 22, which is disposed outside the first container 11. The inlet and outlet of the heat exchange tube 21 are disposed outside the first container 11 and connected to the sealed heating component 22. The heat medium can circulate within the sealed heating component 22 and the heat exchange tube 21. The sealed heating component 22 is used to heat the heat medium. The sealed heating component 22 achieves sealed heating of the heat medium, preventing the heating source from being exposed, ensuring construction safety, and meeting the heating needs of underground coal mines. The circulation of the high-temperature heat medium within the heat exchange tube 21 achieves cyclic heating of the liquid carbon dioxide fracturing agent in the first container 11, thereby achieving temperature control of the liquid carbon dioxide fracturing agent and saving energy.

[0044] More specifically, the heat exchange tube 21 is a metal tube with good heat transfer performance and high heat exchange efficiency. The heat exchange tube 21 extends from the bottom of the first container 11 and extends from the top, that is, the inlet of the heat exchange tube 21 is located on the outside of the bottom of the first container 11, and the outlet of the heat exchange tube 21 is located on the outside of the top of the first container 11. The heat medium first exchanges heat with the liquid carbon dioxide fracturing agent at the bottom of the first container 11. The liquid carbon dioxide fracturing agent at the bottom of the first container 11 is heated first and rises, forming thermal convection in the first container 11, which enhances the heat exchange effect and is conducive to quickly heating the liquid carbon dioxide fracturing agent in the first container 11 to the design temperature, and the heating is uniform.

[0045] Specifically, such as Figure 2 As shown, the heating device 2 also includes a heat exchange valve 23 disposed at the inlet and / or outlet of the heat exchange tube 21. The heat exchange valve 23 is used to control the flow rate of the heat medium in the heat exchange tube 21 located in the first container 11. By controlling the flow rate of the heat medium in the heat exchange tube 21, the heat exchange time between the heat medium and the liquid carbon dioxide fracturing agent in the first container 11 can be controlled, thereby achieving control of the heat exchange temperature difference, and thus raising the temperature of the liquid carbon dioxide fracturing agent in the first container 11 to the design temperature.

[0046] In one specific embodiment, the temperature at the inlet of the heat exchange tube 21 is controlled to be 50-80°C and the temperature at the outlet is controlled to be 25-45°C, thereby achieving a controllable temperature of 30-40°C inside the first container 11.

[0047] Optionally, the heat transfer medium is hydraulic oil. The sealed heating assembly 22 adopts an electric high-temperature oil heater. Through the closed-loop electric heating circulation of hydraulic oil, the high-temperature oil circulation achieves the temperature increase of the liquid carbon dioxide fracturing agent in the first container 11 to the design temperature, realizing rapid heating of the liquid carbon dioxide fracturing agent and improving heating efficiency.

[0048] Optionally, such as Figure 1 As shown, the pumping device 3 includes a fluid fracturing pump 31 and a coal safety-type variable frequency motor 32. The pump inlet of the fluid fracturing pump 31 is connected to the first container 11, and the pump outlet is connected to the fracturing borehole through a pipeline. The coal safety-type variable frequency motor 32 is connected to the fluid fracturing pump 31 and is used to drive the fluid fracturing pump 31. The fluid fracturing pump 31 injects liquid carbon dioxide fracturing agent into the formation fracturing borehole through the pipeline. The fluid fracturing pump 31 can pressurize the liquid carbon dioxide fracturing agent. The coal safety-type variable frequency motor 32 provides pumping power to the fluid fracturing pump 31. Moreover, the coal safety-type variable frequency motor 32 can adjust the rotation frequency, that is, the output power of the coal safety-type variable frequency motor 32 is adjustable, thereby adjusting the pumping pressure of the fluid fracturing pump 31, and thus realizing controllable pumping pressure of liquid carbon dioxide fracturing fluid.

[0049] In one specific embodiment, the fluid fracturing pump 31 is a three-cylinder plunger pump or a five-cylinder plunger pump with a flow rate of 300-700 liters per minute and a controllable pumping pressure range of 2-40 MPa.

[0050] In one specific embodiment, the power of the coal-safe variable frequency motor 32 is 250-500kW.

[0051] Optionally, such as Figure 2 As shown, the pumping device 3 also includes a high-pressure valve 33 and a high-pressure pipeline 34. The pump inlet of the fluid fracturing pump 31 is connected to multiple first containers 11 through the high-pressure valve 33 and the high-pressure pipeline 34. The liquid carbon dioxide fracturing agent in the first container 11 is input into the pumping device 3 through the high-pressure valve 33 and the high-pressure pipeline 34. The high-pressure valve 33 is used to switch between different first containers 11, and the liquid carbon dioxide fracturing agent in multiple first containers 11 can be alternately delivered to the pumping device 3, thereby controlling the input source of the liquid carbon dioxide fracturing agent and ensuring continuous pumping operation and heating time.

[0052] In one specific embodiment, the high-pressure valve is a 33-position high-pressure solenoid valve.

[0053] Optionally, such as Figure 1As shown, the pressure regulating device 4 includes a coal mine-permitted frequency converter, which is connected to the coal safety-type variable frequency motor 32 via control cable 7. The coal mine-permitted frequency converter is the core component for controlling the fluid fracturing pump 31. It regulates the rotation frequency of the coal safety-type variable frequency motor 32, thereby controlling the output power of the motor and ultimately controlling the pumping pressure of the fluid fracturing pump 31.

[0054] In one specific embodiment, the rated input voltage of the permitted frequency converter for coal mines is 660 / 1140V, the speed regulation range is 1:1000 for closed-loop vector and 1:100 for open-loop vector.

[0055] In one specific embodiment, the remote control device 5 serves as the control center for the waterless carbon dioxide pressure pump injection in underground coal mines. It adopts a box-type structure and integrates a server, a programmable signal control system, and a control terminal.

[0056] Optionally, such as Figure 1 As shown, the underground carbon dioxide pumping system in coal mines also includes a storage and transportation device 8. The storage and transportation device 8 includes a second container 81 for holding liquid carbon dioxide fracturing agent. The second container 81 can be connected to or separated from the first container 11; and the storage and transportation device 8 is movable. By setting up the storage and transportation device 8, the second container 81 can pre-store more liquid carbon dioxide fracturing agent. The storage and transportation device 8 is used to quickly replenish the first container 11 with liquid carbon dioxide fracturing agent, ensuring continuous fracturing pumping operations and meeting the needs of large-volume continuous fracturing.

[0057] In one specific embodiment, the second container 81 is a high-pressure liquid storage tank, made of specially made high-strength, thick-walled, pressure-resistant steel, with a pressure resistance of 100MPa. The second container 81 is cylindrical in shape, with a capacity of 2-5 cubic meters, which can be determined according to the actual construction scale.

[0058] Specifically, the storage and transportation equipment 8 also includes a mobile vehicle 82 and a booster pump 83. The second container 81 and the booster pump 83 are mounted on the mobile vehicle 82, and the second container 81 is connected to the first container 11 through the booster pump 83. The mobile vehicle 82 includes a rubber-tired walking mechanism 821 and a hook, which is suitable for connection with underground coal mine transport vehicles. The booster pump 83 is used to transport the liquid carbon dioxide fracturing agent in the second container 81 to the first container 11. The second container 81 and the booster pump 83 are integrated on the mobile vehicle 82, which is compact and suitable for the narrow working space in underground coal mines. Moreover, the rubber-tired walking mechanism 821 is easy to move, and the hook is easy to connect with underground coal mine transport vehicles, making it convenient for the storage and transportation equipment 8 to move in and out of the coal mine.

[0059] In one specific embodiment, the mobile vehicle 82 is a mobile transport flatbed vehicle. The booster pump 83 has a pumping capacity of 0.1 cubic meters per minute, and the booster can increase the fluid pressure to a maximum of 1 MPa.

[0060] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A carbon dioxide injection system for underground coal mines, characterized in that, include: A liquid storage device, including a first container for containing liquid carbon dioxide fracturing agent; The heating device includes a heat exchange tube partially disposed within the first container, the heat exchange tube being adapted for the flow of a heat medium, so that the heat medium flows through the heat exchange tube and exchanges heat with the liquid carbon dioxide fracturing agent in the first container; A pumping device, with its input end connected to the first container and its output end connected to a fracturing borehole, is used to pump the liquid carbon dioxide fracturing agent in the first container to the fracturing borehole. A pressure regulating device, connected to the pumping device, is used to control the pumping pressure of the pumping device within the coal mine. as well as A remote control device is connected to the heating device, the pumping device, and the pressure regulating device via a signal cable, and is used to control the heating device, the pumping device, and the pressure regulating device from outside the coal mine. The liquid storage device includes two first containers, and the heating device is disposed between the two first containers; the two first containers are used to alternately deliver the liquid carbon dioxide fracturing agent to the pumping device; The pumping device includes a fluid fracturing pump and a coal safety type variable frequency motor. The pump inlet of the fluid fracturing pump is connected to the first container, and the pump outlet is connected to the fracturing borehole through a pipeline. The coal safety type variable frequency motor is connected to the fluid fracturing pump. The temperature at the inlet of the heat exchange tube is controlled at 50-80℃, and the temperature at the outlet is controlled at 25-45℃, thereby achieving a controllable temperature of 30-40℃ inside the first container; The controllable pumping pressure range of the fluid fracturing pump is 2-40 MPa.

2. The carbon dioxide injection system for underground coal mines according to claim 1, characterized in that, The heating device further includes a sealed heating component, which is disposed outside the first container. The inlet and outlet of the heat exchange tube are disposed outside the first container and connected to the sealed heating component. The heat medium can circulate within the sealed heating component and the heat exchange tube. The sealed heating component is used to heat the heat medium.

3. The carbon dioxide injection system for underground coal mines according to claim 2, characterized in that, The heating device further includes a heat exchange valve disposed at the inlet and / or outlet of the heat exchange tube, the heat exchange valve being used to control the flow rate of the heat medium within the heat exchange tube located in the first container.

4. The carbon dioxide injection system for underground coal mines according to claim 2, characterized in that, The heat exchange tube extends into the first container from the bottom and extends out of the first container from the top.

5. The carbon dioxide injection system for underground coal mines according to claim 1, characterized in that, The pressure regulating device includes a coal mine-permitted frequency converter, which is connected to the coal safety type frequency converter motor via a control cable.

6. The carbon dioxide injection system for underground coal mines according to claim 1, characterized in that, The pumping device also includes a high-pressure valve, through which the pump inlet of the fluid fracturing pump is connected to the two first containers.

7. The carbon dioxide injection system for underground coal mines according to any one of claims 1 to 6, characterized in that, The underground carbon dioxide injection system in the coal mine also includes storage and transportation equipment, which includes a second container for containing liquid carbon dioxide fracturing agent. The second container can be connected to or separated from the first container; and the storage and transportation equipment is movable.

8. The carbon dioxide injection system for underground coal mines according to claim 7, characterized in that, The storage and transportation equipment also includes a mobile vehicle and a booster pump. The second container and the booster pump are mounted on the mobile vehicle, and the second container is connected to the first container through the booster pump. The mobile vehicle includes a rubber-wheeled walking mechanism and a hook, which is adapted to be connected to a coal mine underground transport vehicle.

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